Left heart pacing lead implantation using subxiphoid videopericardioscopy.

PubMed

Zenati, Marco A; Bonanomi, Gianluca; Chin, Albert K; Schwartzman, David

2003-09-01

Recent clinical data support the utility of left heart pacing. The transvenous approach for left heart pacing lead implantation is imperfect. A direct epicardial approach may have advantages, but heretofore its utility has been limited because of the requirement for thoracotomy. We sought to examine the feasibility of a method for epicardial lead implantation that did not require thoracotomy. In five large swine, percutaneous access to the epicardium was achieved with subxiphoid videopericardioscopy, using a device that marries endoscopy with a port through which pacing leads could be introduced. In each animal, standard, active fixation pacing leads were implanted onto the left atrium and ventricle. The atrial lead was implanted at the base of the appendage. The ventricular lead was implanted on the anterior, lateral, and inferior walls. Continuous direct visualization of the epicardium provided guidance for lead localization and fixation, including avoidance of complications such as trauma to epicardial coronary vessels. Capture thresholds were uniformly low. Postmortem examination demonstrated anatomically accurate, uncomplicated lead fixation. Using subxiphoid videopericardioscopy, uncomplicated, anatomically accurate left heart epicardial pacing lead implantation can be achieved without thoracotomy.

Effect of Smaller Left Ventricular Capture Threshold Safety Margins to Improve Device Longevity in Recipients of Cardiac Resynchronization-Defibrillation Therapy.

PubMed

Steinhaus, Daniel A; Waks, Jonathan W; Collins, Robert; Kleckner, Karen; Kramer, Daniel B; Zimetbaum, Peter J

2015-07-01

Device longevity in cardiac resynchronization therapy (CRT) is affected by the pacing capture threshold (PCT) and programmed pacing amplitude of the left ventricular (LV) pacing lead. The aims of this study were to evaluate the stability of LV pacing thresholds in a nationwide sample of CRT defibrillator recipients and to determine potential longevity improvements associated with a decrease in the LV safety margin while maintaining effective delivery of CRT. CRT defibrillator patients in the Medtronic CareLink database were eligible for inclusion. LV PCT stability was evaluated using ≥2 measurements over a 14-day period. Separately, a random sample of 7,250 patients with programmed right atrial and right ventricular amplitudes ≤2.5 V, LV thresholds ≤ 2.5 V, and LV pacing ≥90% were evaluated to estimate theoretical battery longevity improvement using LV safety margins of 0.5 and 1.5 V. Threshold stability analysis in 43,256 patients demonstrated LV PCT stability of <0.5 V in 77% of patients and <1 V in 95%. Device longevity analysis showed that the use of a 0.5-V safety margin increased average battery longevity by 0.62 years (95% confidence interval 0.61 to 0.63) compared with a safety margin of 1.5 V. Patients with LV PCTs >1 V had the greatest increases in battery life (mean increase 0.86 years, 95% confidence interval 0.85 to 0.87). In conclusion, nearly all CRT defibrillator patients had LV PCT stability <1.0 V. Decreasing the LV safety margin from 1.5 to 0.5 V provided consistent delivery of CRT for most patients and significantly improved battery longevity. Copyright © 2015 Elsevier Inc. All rights reserved.

Ablation and pacing: improving brain perfusion and cognitive function in patients with atrial fibrillation and uncontrolled ventricular rates.

PubMed

Efimova, Irina; Efimova, Nataliya; Chernov, Vladimir; Popov, Sergey; Lishmanov, Yuri

2012-03-01

The aim of our study was to determine if ablation and pacing improved brain perfusion (BP) and cognitive function (CF) in patients with medically refractory rapidly conducted atrial fibrillation (Med Refr RCAF). The study included 17 patients with Med Refr RCAF (average age 55.3 ± 4.5 years). All patients underwent brain single photon emission computed tomography scanning with (99m) Tc-hexamethylpropylene amine oxime and comprehensive neuropsychological testing before and after 3 months following pacemaker implantation. The BP was significantly lower in all regions in patients with Med Refr RCAF compared with the control group. The greatest BP decrease was revealed in the inferior frontal (P = 0.002) and posterior parietal (P = 0.024) brain regions. These patients showed cognitive deficit in 94%. There was a direct correlation between BP and CF parameters. Ablation followed by pacemaker implantation had a positive effect on BP and CF in all patients with Med Refr RCAF. Thus, BP increased in the right inferior frontal (P = 0.01), in the left superior frontal (P = 0.007), and in the left temporal (P = 0.005) cortex. These patients demonstrated improvements in immediate and delayed verbal memory, immediate and delayed visual memory, abstract mentation, attention, psychomotor speed, as well as in learning. Patients with atrial fibrillation and rapid ventricular rates refractory to medical treatment have marked signs of brain hypoperfusion and impaired CF. Ablation and pacing improve left ventricular systolic function, thereby increasing BP and improving CF. ©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.

Epicardial left ventricular lead placement for cardiac resynchronization therapy: optimal pace site selection with pressure-volume loops.

PubMed

Dekker, A L A J; Phelps, B; Dijkman, B; van der Nagel, T; van der Veen, F H; Geskes, G G; Maessen, J G

2004-06-01

Patients in heart failure with left bundle branch block benefit from cardiac resynchronization therapy. Usually the left ventricular pacing lead is placed by coronary sinus catheterization; however, this procedure is not always successful, and patients may be referred for surgical epicardial lead placement. The objective of this study was to develop a method to guide epicardial lead placement in cardiac resynchronization therapy. Eleven patients in heart failure who were eligible for cardiac resynchronization therapy were referred for surgery because of failed coronary sinus left ventricular lead implantation. Minithoracotomy or thoracoscopy was performed, and a temporary epicardial electrode was used for biventricular pacing at various sites on the left ventricle. Pressure-volume loops with the conductance catheter were used to select the best site for each individual patient. Relative to the baseline situation, biventricular pacing with an optimal left ventricular lead position significantly increased stroke volume (+39%, P =.01), maximal left ventricular pressure derivative (+20%, P =.02), ejection fraction (+30%, P =.007), and stroke work (+66%, P =.006) and reduced end-systolic volume (-6%, P =.04). In contrast, biventricular pacing at a suboptimal site did not significantly change left ventricular function and even worsened it in some cases. To optimize cardiac resynchronization therapy with epicardial leads, mapping to determine the best pace site is a prerequisite. Pressure-volume loops offer real-time guidance for targeting epicardial lead placement during minimal invasive surgery.

The effects of hypoxemia on myocardial blood flow during exercise.

PubMed

Paridon, S M; Bricker, J T; Dreyer, W J; Reardon, M; Smith, E O; Porter, C B; Michael, L; Fisher, D J

1989-03-01

We evaluated the adequacy of regional and transmural blood flow during exercise and rapid pacing after 1 wk of hypoxemia. Seven mature mongrel dogs were made hypoxemic (mean O2 saturation = 72.4%) by anastomosis of left pulmonary artery to left atrial appendage. Catheters were placed in the left atrium, right atrium, pulmonary artery, and aorta. Atrial and ventricular pacing wires were placed. An aortic flow probe was placed to measure cardiac output. Ten nonshunted dogs, similarly instrumented, served as controls. Recovery time was approximately 1 wk. Cardiac output, mean aortic pressure, and oxygen saturation were measured at rest, with ventricular pacing, atrial pacing, and with treadmill exercise. Ventricular and atrial pace and exercise were at a heart rate of 200. Right ventricular free wall, left ventricular free wall, and septal blood flow were measured with radionuclide-labeled microspheres. Cardiac output, left atrial blood pressure, and aortic blood pressure were similar between the two groups of dogs in all testing states. Myocardial blood flow was significantly higher in the right and left ventricular free wall in the hypoxemic animals during resting and exercise testing states. Myocardial oxygen delivery was similar between the two groups of animals. Pacing resulted in an increase in myocardial blood flow in the control animals but not the hypoxemic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Pressure-derived indices of left ventricular isovolumic relaxation in patients with hypertrophic cardiomyopathy.

PubMed Central

Thompson, D S; Wilmshurst, P; Juul, S M; Waldron, C B; Jenkins, B S; Coltart, D J; Webb-Peploe, M M

1983-01-01

High fidelity measurements of left ventricular pressure were made at increasing pacing rates in 21 patients with hypertrophic cardiomyopathy and a control group of 11 patients investigated for chest pain who proved to have normal hearts. In both groups the fall in pressure during isovolumic relaxation from the point of min dp/dt approximated closely to a monoexponential, and could be described by a time constant and asymptote. The time constant shortened and the asymptote increased as heart rate rose in both groups. The time constant was longer and min dp/dt less in the cardiomyopathy group than controls at all heart rates. In the cardiomyopathy patients min dp/dt, but not the time constant, was related to systolic pressure. During pacing, eight cardiomyopathy patients developed metabolic evidence of myocardial ischaemia, but indices of relaxation did not differ between these eight and the other 13 either at basal heart rate or the highest pacing rate. In 10 cardiomyopathy patients measurements were repeated at comparable pacing rates after propranolol (0.2 mg/kg). Left ventricular end-diastolic pressure and indices of contractility decreased after the drug, but the time constant did not change. Eight patients received verapamil (20 mg) after which there were substantial reductions in systolic pressure and contractility. Min dp/dt decreased in proportion to systolic pressure, but the time constant was unchanged. At the highest pacing rate before drug administration three patients had abnormal lactate extraction which was corrected by either propranolol (one patient) or verapamil (two patients). Despite abolition of metabolic evidence of ischaemia, relaxation did not improve. It is concluded that abnormal isovolumic relaxation is common in patients with hypertrophic cardiomyopathy, but its severity correlates poorly with other features of the disease. Abnormal relaxation is not the result of ischaemia, and pressure derived indices of relaxation do not improve after the administration of propranolol or verapamil. PMID:6681978

Is right ventricular mid-septal pacing superior to apical pacing in patients with high degree atrio-ventricular block and moderately depressed left ventricular function?

PubMed

Chen, Kang; Mao, Ye; Liu, Shao-hua; Wu, Qiong; Luo, Qing-zhi; Pan, Wen-qi; Jin, Qi; Zhang, Ning; Ling, Tian-you; Chen, Ying; Gu, Gang; Shen, Wei-feng; Wu, Li-qun

2014-06-01

We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ventricular ejection fraction (LVEF) for patients with high-degree atrio-ventricular block and moderately depressed left ventricle (LV) function. Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF (ranging from 35% to 50%) were randomly allocated to RVMSP (n=45) and RVAP (n=47). New York Heart Association (NYHA) functional class, echocardiographic LVEF, and distance during a 6-min walk test (6MWT) were determined at 18 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MWT (485 m vs. 517 m) and LVEF (36.7% vs. 41.8%) were increased, but BNP levels were reduced (2352 pg/ml vs. 710 pg/ml) in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%-40% (for all comparisons, P<0.05). However, clinical function capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.

Right Ventricular Outflow Tract Septal Pacing Is Superior to Right Ventricular Apical Pacing

PubMed Central

Zou, Cao; Song, Jianping; Li, Hui; Huang, Xingmei; Liu, Yuping; Zhao, Caiming; Shi, Xin; Yang, Xiangjun

2015-01-01

Background The effects of right ventricular apical pacing (RVAP) and right ventricular outflow tract (RVOT) septal pacing on atrial and ventricular electrophysiology have not been thoroughly compared. Methods and Results To identify a more favorable pacing strategy with fewer adverse effects, 80 patients who had complete atrioventricular block with normal cardiac function and who were treated with either RVAP (n=42) or RVOT septal pacing (n=38) were recruited after an average of 2 years of follow‐up. The data from electrocardiography and echocardiography performed before pacemaker implantation and at the end of follow‐up were collected. The patients in the RVOT septal pacing and RVAP groups showed similar demographic and clinical characteristics before pacing treatments. After a mean follow‐up of 2 years, the final maximum P‐wave duration; P‐wave dispersion; Q‐, R‐, and S‐wave complex duration; left atrial volume index; left ventricular end‐systolic diameter; ratio of transmitral early diastolic filling velocity to mitral annular early diastolic velocity; and interventricular mechanical delay in the RVOT septal pacing group were significantly less than those in the RVAP group (P<0.05). The final left ventricular ejection fraction of the RVOT septal pacing group was significantly higher than that of the RVAP group (P<0.05). Conclusions Compared with RVAP, RVOT septal pacing has fewer adverse effects regarding atrial electrical activity and structure in patients with normal cardiac function. PMID:25896891

Using left-ventricular-only pacing to eliminate T-wave oversensing in a biventricular implantable cardiac defibrillator.

PubMed

Khoo, Clarence; Bennett, Matthew; Chakrabarti, Santabhanu; LeMaitre, John; Tung, Stanley K K

2013-02-01

A man aged 75 years and with nonischemic cardiomyopathy had implantation of a biventricular implantable cardiac defibrillator (ICD). Consistent biventricular pacing was limited by intermittent T-wave oversensing (TWOS). A strategy of left-ventricular-only pacing was used to eliminate TWOS. This strategy obviates the need to reduce ventricular sensitivity and thus may be an effective alternative to biventricular pacing complicated by TWOS. Copyright © 2013 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Hybrid Therapy in the Management of Atrial Fibrillation

PubMed Central

Stárek, Zdeněk; Lehar, František; Jež, Jiří; Wolf, Jiří; Novák, Miroslav

2015-01-01

Atrial fibrillation is the most common sustained arrhythmia. Because of the sub-optimal outcomes and associated risks of medical therapy as well as the recent advances in non-pharmacologic strategies, a multitude of combined (hybrid) algorithms have been introduced that improve efficacy of standalone therapies while maintaining a high safety profile. Antiarrhythmic administration enhances success rate of electrical cardioversion. Catheter ablation of antiarrhythmic drug-induced typical atrial flutter may prevent recurrent atrial fibrillation. Through simple ablation in the right atrium, suppression of atrial fibrillation may be achieved in patients with previously ineffective antiarrhythmic therapy. Efficacy of complex catheter ablation in the left atrium is improved with antiarrhythmic drugs. Catheter ablation followed by permanent pacemaker implantation is an effective and safe treatment option for selected patients. Additional strategies include pacing therapies such as atrial pacing with permanent pacemakers, preventive pacing algorithms, and/or implantable dual-chamber defibrillators are available. Modern hybrid strategies combining both epicardial and endocardial approaches in order to create a complex set of radiofrequency lesions in the left atrium have demonstrated a high rate of success and warrant further research. Hybrid therapy for atrial fibrillation reviews history of development of non-pharmacological treatment strategies and outlines avenues of ongoing research in this field. PMID:25028165

[Role of cyclic adenosine monophosphate response element binding protein in ventricular pacing induced cardiac electrical remodeling in a canine model].

PubMed

Chen, Xuesi; Chen, Xingxing; Cheng, Junhua; Hong, Jun; Zheng, Cheng; Zhao, Jinglin; Li, Jin; Lin, Jiafeng

2015-04-01

This project is designed to explore the potential role of cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) in cardiac electrical remodeling induced by pacing at different ventricular positions in dogs. An animal model by implanting the pacemakers in beagles was established. According to the different pacing positions, the animals were divided into 4 groups:conditional control group (n=6), left ventricle pacing group (n=6), right ventricle pacing group (n=6) and bi-ventricle pacing group (n=6). Cardiac and electrical remodeling were observed by echocardiography, electrocardiogram and plasma BNP. Myocardial pathology and protein expression of extracellular regulated protein kinases1/2 (ERK1/2), P38 mitogen activated protein kinases (P38 MAPK) and CREB were examined at 4 weeks post pacing. Cardiac structure and plasma BNP level were similar among 4 groups (all P>0.05). Electrocardiogram derived Tp-Te interval was significantly prolonged post pacing (92±11, 91±10, and 79±13 ms vs. 60±12 ms), and the Tp-Te interval in bi-ventricle pacing group was shorter than in left or right ventricle pacing group (P < 0.05). Western blot results showed that the expression of p-ERK1/2 in left ventricular myocardium of left ventricle pacing group, right ventricular myocardium of right ventricle pacing group and bi-ventricular myocardium of bi-ventricle pacing group was 2.7±0.4, 2.4±0.2, 1.7±0.1 and 1.9±0.2, respectively, the expression of p-P38 MAPK was 1.9±0.3, 1.7±0.2, 0.8±0.1 and 1.1±0.1, respectively, and the expression of p-CREB was 2.1±0.2, 2.0±0.2, 2.7±0.4 and 2.6±0.3, respectively. The p-ERK1/2 and p-P38 MAPK expression of bi-ventricle pacing group was lower,but the p-CREB expression was higher compared to the other pacing groups (P < 0.05). Ventricular pacing could induce electrical remodeling evidenced by prolonged Tp-Te interval and increased phosphorylation of ERK1/2 and p38 MAPK and reduced phosphorylation of CREB. Compared with single ventricle pacing, bi-ventricle pacing could attenuate electrical remodeling in this model.

Benefits of Permanent His Bundle Pacing Combined With Atrioventricular Node Ablation in Atrial Fibrillation Patients With Heart Failure With Both Preserved and Reduced Left Ventricular Ejection Fraction.

PubMed

Huang, Weijian; Su, Lan; Wu, Shengjie; Xu, Lei; Xiao, Fangyi; Zhou, Xiaohong; Ellenbogen, Kenneth A

2017-04-01

Clinical benefits from His bundle pacing (HBP) in heart failure patients with preserved and reduced left ventricular ejection fraction are still inconclusive. This study evaluated clinical outcomes of permanent HBP in atrial fibrillation patients with narrow QRS who underwent atrioventricular node ablation for heart failure symptoms despite rate control by medication. The study enrolled 52 consecutive heart failure patients who underwent attempted atrioventricular node ablation and HBP for symptomatic atrial fibrillation. Echocardiographic left ventricular ejection fraction and left ventricular end-diastolic dimension, New York Heart Association classification and use of diuretics for heart failure were assessed during follow-up visits after permanent HBP. Of 52 patients, 42 patients (80.8%) received permanent HBP and atrioventricular node ablation with a median 20-month follow-up. There was no significant change between native and paced QRS duration (107.1±25.8 versus 105.3±23.9 milliseconds, P =0.07). Left ventricular end-diastolic dimension decreased from the baseline ( P <0.001), and left ventricular ejection fraction increased from baseline ( P <0.001) in patients with a greater improvement in heart failure with reduced ejection fraction patients (N=20) than in heart failure with preserved ejection fraction patients (N=22). New York Heart Association classification improved from a baseline 2.9±0.6 to 1.4±0.4 after HBP in heart failure with reduced ejection fraction patients and from a baseline 2.7±0.6 to 1.4±0.5 after HBP in heart failure with preserved ejection fraction patients. After 1 year of HBP, the numbers of patients who used diuretics for heart failure decreased significantly ( P <0.001) when compared to the baseline diuretics use. Permanent HBP post-atrioventricular node ablation significantly improved echocardiographic measurements and New York Heart Association classification and reduced diuretics use for heart failure management in atrial fibrillation patients with narrow QRS who suffered from heart failure with preserved or reduced ejection fraction. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Prevention of Adverse Electrical and Mechanical Remodeling with Bi-Ventricular Pacing in a Rabbit Model of Myocardial Infarction

PubMed Central

Saba, Samir; Mathier, Michael A.; Mehdi, Haider; Gursoy, Erdal; Liu, Tong; Choi, Bum-Rak; Salama, Guy; London, Barry

2008-01-01

Background: Biventricular (BIV) pacing can improve cardiac function in heart failure (HF). Objective: To investigate the mechanisms of benefit of BIV pacing using a rabbit model of myocardial infarction (MI). Methods: New Zealand White rabbits were divided into 4 groups: sham-operated (C), MI with no pacing (MI), MI with right ventricular pacing (MI+RV), and MI with BIV pacing (MI+BIV), and underwent serial electrocardiograms and echocardiograms. At 4 weeks, hearts were excised and tissue was extracted from various areas of the left ventricle (LV). Results: Four weeks after coronary ligation, BIV pacing prevented systolic and diastolic dilation of the LV as well as the reduction in its fractional shortening, restored the QRS width and the rate-dependent QT intervals to their baseline values, and prevented the decline of the ether-a-go-go (erg) protein levels. This prevention of remodeling was not documented in the MI+RV groups. Conclusions: In this rabbit model of BIV pacing and MI, we demonstrate prevention of adverse mechanical and electrical remodeling of the heart. These changes may underlie some of the benefits seen with BIV pacing in HF patients with more severe LV dysfunction. PMID:18180026

Left atrial booster function in valvular heart disease.

PubMed

Heidenreich, F P; Shaver, J A; Thompson, M E; Leonard, J J

1970-09-01

This study was designed to assess atrial booster pump action in valvular heart disease and to dissect booster pump from reservoir-conduit functions. In five patients with aortic stenosis and six with mitral stenosis, sequential atrioventricular (A-V) pacing was instituted during the course of diagnostic cardiac catheterization. Continuous recording of valvular gradient allowed estimation of flow for each cardiac cycle by transposition of the Gorlin formula. Left ventricular ejection time and left ventricular stroke work in aortic stenosis or left ventricular mean systolic pressure in mitral stenosis were also determined. Control observations were recorded during sequential A-V pacing with well-timed atrial systole. Cardiac cycles were then produced with no atrial contraction but undisturbed atrial reservoir function by intermittently interrupting the atrial pacing stimulus during sequential A-V pacing. This intervention significantly reduced valvular gradient, flow, left ventricular ejection time, and left ventricular mean systolic pressure or stroke work. Cardiac cycles were then produced with atrial booster action eliminated by instituting synchronous A-V pacing. The resultant simultaneous contraction of the atrium and ventricle not only eliminated effective atrial systole but also placed atrial systole during the normal period of atrial reservoir function. This also significantly reduced all the hemodynamic measurements. However, comparison of the magnitude of change from these two different pacing interventions showed no greater impairment of hemodynamic state when both booster pump action and reservoir function were impaired than when booster pump action alone was impaired. The study confirms the potential benefit of well placed atrial booster pump action in valvular heart disease in man.

Systematic review and meta-analysis of left ventricular endocardial pacing in advanced heart failure: Clinically efficacious but at what cost?

PubMed

Graham, Adam J; Providenica, Rui; Honarbakhsh, Shohreh; Srinivasan, Neil; Sawhney, Vinit; Hunter, Ross; Lambiase, Pier

2018-04-01

Cardiac resynchronization using a left ventricular (LV) epicardial lead placed in the coronary sinus is now routinely used in the management of heart failure patients. LV endocardial pacing is an alternative when this is not feasible, with outcomes data sparse. To review the available evidence on the efficacy and safety of endocardial LV pacing via meta-analysis. EMBASE, MEDLINE, and COCHRANE databases with the search term "endocardial biventricular pacing" or "endocardial cardiac resynchronization" or "left ventricular endocardial" or "endocardial left ventricular." Comparisons of pre-and post-QRS width, LV ejection fraction (LVEF), and New York Heart Association (NYHA) functional classification was performed, and mean differences (and respective 95% confidence interval [CI]) applied as a measurement of treatment effect. Fifteen studies, including 362 patients, were selected. During a mean follow-up of 40 ± 24.5 months, death occurred in 72 patients (11 per 100 patient-years). Significant improvements in LVEF (mean difference 7.9%, 95% CI 5-10%, P < 0.0001; I 2  = 73%), QRS width (mean difference: -41% 95% -75 to -7%; P < 0.0001; I 2  = 94%), and NYHA class (mean difference: -1.06, 95% CI -1.2 to -0.9, P < 0.0001; I 2  = 60%), (all P < 0.0001) occurred. Stroke rate was 3.3-4.2 per 100 patient-years, which is higher than equivalent heart failure trial populations and recent meta-analysis that included small case series. LV endocardial lead implantation is a potentially efficacious alternative to CS lead placement, but preliminary data suggest a potentially higher risk of stroke during follow-up when compared to the expected incidence of stroke in similar cohorts of patients. © 2018 Wiley Periodicals, Inc.

Different regions of latest electrical activation during left bundle-branch block and right ventricular pacing in cardiac resynchronization therapy patients determined by coronary venous electro-anatomic mapping.

PubMed

Mafi Rad, Masih; Blaauw, Yuri; Dinh, Trang; Pison, Laurent; Crijns, Harry J; Prinzen, Frits W; Vernooy, Kevin

2014-11-01

Current targeted left ventricular (LV) lead placement strategy is directed at the latest activated region during intrinsic activation. However, cardiac resynchronization therapy (CRT) is most commonly applied by simultaneous LV and right ventricular (RV) pacing without contribution from intrinsic conduction. Therefore, targeting the LV lead to the latest activated region during RV pacing might be more appropriate. We investigated the difference in LV electrical activation sequence between left bundle-branch block (LBBB) and RV apex (RVA) pacing using coronary venous electro-anatomic mapping (EAM). Twenty consecutive CRT candidates with LBBB underwent intra-procedural coronary venous EAM during intrinsic activation and RVA pacing using EnSite NavX. Left ventricular lead placement was aimed at the latest activated region during LBBB according to current recommendations. In all patients, LBBB was associated with a circumferential LV activation pattern, whereas RVA pacing resulted in activation from the apex of the heart to the base. In 10 of 20 patients, RVA pacing shifted the latest activated region relative to LBBB. In 18 of 20 patients, the LV lead was successfully positioned in the latest activated region during LBBB. For the whole study population, LV lead electrical delay, expressed as percentage of QRS duration, was significantly shorter during RVA pacing than during LBBB (72 ± 13 vs. 82 ± 5%, P = 0.035). Right ventricular apex pacing alters LV electrical activation pattern in CRT patients with LBBB, and shifts the latest activated region in a significant proportion of these patients. These findings warrant reconsideration of the current practice of LV lead targeting for CRT. © 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.

Randomized, double-blind trial of simultaneous right and left atrial epicardial pacing for prevention of post-open heart surgery atrial fibrillation.

PubMed

Daoud, E G; Dabir, R; Archambeau, M; Morady, F; Strickberger, S A

2000-08-15

The purpose of this study was to assess simultaneous right and left atrial pacing as prophylaxis for postoperative atrial fibrillation. In a double-blind, randomized fashion, 118 patients who underwent open heart surgery were assigned to right atrial pacing at 45 bpm (RA-AAI; n=39), right atrial triggered pacing at a rate of >/=85 bpm (RA-AAT; n=38), or simultaneous right and left atrial triggered pacing at a rate of >/=85 bpm (Bi-AAT; n=41). Holter monitoring was performed for 4. 8+/-1.4 days after surgery to assess for episodes of atrial fibrillation lasting >5 minutes. The prevalence of postoperative atrial fibrillation was significantly less in the patients randomized to biatrial AAT pacing when compared with the other 2 pacing regimens (P=0.02). An episode of atrial fibrillation occurred in 4 (10%) of 41 patients in the Bi-AAT group compared with 11 (28%) of 39 patients in the RA-AAI group (P=0.03 versus Bi-AAT) and 12 (32%) of 38 patients in the RA-AAT group (P=0.01 versus Bi-AAT). There was no difference in the occurrence of atrial fibrillation between the right atrial AAI and AAT groups (P=0.8). There was no significant difference among the 3 groups with regard to the number of postoperative hospital days (7.3+/-4.2 days), morbidity (5.1%), or mortality rate (2.5%). Simultaneous right and left atrial triggered pacing is well tolerated and significantly reduces the prevalence of post-open heart surgery atrial fibrillation.

Temporary atrial epicardial pacing as prophylaxis against atrial fibrillation after heart surgery: a meta-analysis.

PubMed

Daoud, Emile G; Snow, Rick; Hummel, John D; Kalbfleisch, Steven J; Weiss, Raul; Augostini, Ralph

2003-02-01

Recent studies have reported the use of temporary epicardial atrial pacing as prophylaxis for postoperative atrial fibrillation (AF). The aim of this study was to assess the effect of pacing therapies for prevention of postoperative AF using meta-analysis. Using a computerized MEDLINE search, eight pacing prophylaxis trials with 776 patients were included in the meta-analysis. Trials compared control patients to patients randomized to right atrial, left atrial, or biatrial pacing used in conjunction with either fixed high-rate pacing or overdrive pacing. Overdrive biatrial pacing (OR 2.6, CI 1.4-4.8), overdrive right atrial pacing (OR 1.8, CI 1.1-2.7), and fixed high-rate biatrial pacing (OR 2.5, CI 1.3-5.1) demonstrated a significant antiarrhythmic effect for prevention of AF after open heart surgery. Furthermore, studies investigating overdrive left atrial pacing and fixed high-rate right atrial pacing have been underpowered to assess efficacy. Biatrial overdrive and fixed high-rate pacing and right atrial fixed high-rate pacing reduced the risk of new-onset AF after open heart surgery, and the relative risk reduction is approximately 2.5-fold. These results imply that various pacing algorithms are useful as a nonpharmacologic method to prevent postoperative AF.

The Post-Myocardial Infarction Pacing Remodeling Prevention Therapy (PRomPT) Trial: Design and Rationale.

PubMed

Chung, Eugene S; Fischer, Trent M; Kueffer, Fred; Anand, Inder S; Bax, Jeroen J; Gold, Michael R; Gorman, Robert C; Theres, Heinz; Udelson, James E; Stancak, Branislav; Svendsen, Jesper H; Stone, Gregg W; Leon, Angel

2015-07-01

Despite considerable improvements in the medical management of patients with myocardial infarction (MI), patients with large MI still have substantial risk of developing heart failure. In the early post-MI setting, implantable cardioverter defibrillators have reduced arrhythmic deaths but have no impact on overall mortality. Therefore, additional interventions are required to further reduce the overall morbidity and mortality of patients with large MI. The Pacing Remodeling Prevention Therapy (PRomPT) trial is designed to study the effects of peri-infarct pacing in preventing adverse post-MI remodeling. Up to 120 subjects with peak creatine phosphokinase >3,000 U/L (or troponin T >10 μg/L) at time of MI will be randomized to either dual-site or single-site biventricular pacing with the left ventricular lead implanted in a peri-infarct region or to a nonimplanted control group. Those randomized to a device will be blinded to the pacing mode, but randomization to a device or control cannot be blinded. Subjects randomized to pacing will have the device implanted within 10 days of MI. The primary objective is to assess the change in left ventricular end-diastolic volume from baseline to 18 months. Secondary objectives are to assess changes in clinical and mechanistic parameters between the groups, including rates of hospitalization for heart failure and cardiovascular events, the incidence of sudden cardiac death and all-cause mortality, New York Heart Association functional class, 6-minute walking distance, and quality of life. The PRomPT trial will provide important evidence regarding the potential of peri-infarct pacing to interrupt adverse remodeling in patients with large MI. Copyright © 2015 Elsevier Inc. All rights reserved.

Cardiomyoplasty: first clinical case with new cardiomyostimulator.

PubMed

Chekanov, Valeri S; Sands, Duane E; Brown, Conville S; Brum, Fernando; Arzuaga, Pedro; Gava, Sebastian; Eugenio, Ferdinand P; Melamed, Vladimir; Spencer, Howard W

2002-09-01

Dynamic cardiomyoplasty was performed in a patient using a new cardio-myostimulator (LD-PACE II) designed to enable a novel stimulation regimen that utilizes a new range of stimulation options, including cessation during sleep. After treatment, left ventricular ejection fraction improved in 24 months from 15% to 25% and New York Heart Association classification improved from class IV to II.

Programming Cardiac Resynchronization Therapy for Electrical Synchrony: Reaching Beyond Left Bundle Branch Block and Left Ventricular Activation Delay.

PubMed

Varma, Niraj; O'Donnell, David; Bassiouny, Mohammed; Ritter, Philippe; Pappone, Carlo; Mangual, Jan; Cantillon, Daniel; Badie, Nima; Thibault, Bernard; Wisnoskey, Brian

2018-02-06

QRS narrowing following cardiac resynchronization therapy with biventricular (BiV) or left ventricular (LV) pacing is likely affected by patient-specific conduction characteristics (PR, qLV, LV-paced propagation interval), making a universal programming strategy likely ineffective. We tested these factors using a novel, device-based algorithm (SyncAV) that automatically adjusts paced atrioventricular delay (default or programmable offset) according to intrinsic atrioventricular conduction. Seventy-five patients undergoing cardiac resynchronization therapy (age 66±11 years; 65% male; 32% with ischemic cardiomyopathy; LV ejection fraction 28±8%; QRS duration 162±16 ms) with intact atrioventricular conduction (PR interval 194±34, range 128-300 ms), left bundle branch block, and optimized LV lead position were studied at implant. QRS duration (QRSd) reduction was compared for the following pacing configurations: nominal simultaneous BiV (Mode I: paced/sensed atrioventricular delay=140/110 ms), BiV+SyncAV with 50 ms offset (Mode II), BiV+SyncAV with offset that minimized QRSd (Mode III), or LV-only pacing+SyncAV with 50 ms offset (Mode IV). The intrinsic QRSd (162±16 ms) was reduced to 142±17 ms (-11.8%) by Mode I, 136±14 ms (-15.6%) by Mode IV, and 132±13 ms (-17.8%) by Mode II. Mode III yielded the shortest overall QRSd (123±12 ms, -23.9% [ P <0.001 versus all modes]) and was the only configuration without QRSd prolongation in any patient. QRS narrowing occurred regardless of QRSd, PR, or LV-paced intervals, or underlying ischemic disease. Post-implant electrical optimization in already well-selected patients with left bundle branch block and optimized LV lead position is facilitated by patient-tailored BiV pacing adjusted to intrinsic atrioventricular timing using an automatic device-based algorithm. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

A clinical comparison between a new dual-chamber pacing mode-AAIsafeR and DDD mode.

PubMed

Xue-Jun, Ren; Zhihong, Han; Ye, Wang; Huifeng, Du; Jinrong, Zhang; Fang, Chen; Jihong, Guo

2010-02-01

The aim of this study was to compare the cross-follow-up results in DDD or AAISafeR mode and to describe the safety and effectiveness of this pacing mode. The Symphony 2450/2550 cardiac pacemakers were implanted in 30 patients with sick sinus syndrome between February 2006 and September 2006. They were randomized to the DDD mode or AAISafeR mode for 3 months and then crossed over to the alternate pacing modality for an additional 3 months. No AAISafeR-related adverse event was observed. All documented episodes of paroxysmal atrial ventricular block caused the immediate switch of the pacing mode from AAI to DDD. The cumulative percent ventricular pacing was significantly reduced in the AAISafeR mode compared with the DDD mode (0.9% [0%-3%] versus 51.3% [2%-91%] P = 0.001; 2.94% [0%-18%] versus 41.18% [0%-65%] P = 0.0001). After 3 months in DDD mode, left atrial diameter, left ventricular enddiastolic diameter, and left ventricular end-systolic diameter increased significantly and left ventricular ejection fraction decreased. However, no obvious changes appeared in 3 months of AAISafeR mode. Switches to DDD occurred during follow-up in 21 patients due to different-degree atrial ventricular block. The AAISafeR mode substantially reduces the amount of unnecessary right ventricular pacing in the bradycardia population and effectively prevents the deleterious effects on cardiac performance. An international randomized study will further ascertain the efficacy of this new pacing mode specifically in the prevention of heart failure hospitalization and atrial fibrillation.

Pacing from the right ventricular septum: is there a danger to the coronary arteries?

PubMed

Teh, Andrew W; Medi, Caroline; Rosso, Raphael; Lee, Geoffrey; Gurvitch, Ronen; Mond, Harry G

2009-07-01

Pacing from right ventricular (RV) septal sites has been suggested as an alternative to RV apical pacing in an attempt to avoid long-term adverse consequences on left ventricular function. Concern has been raised as to the relationship of the left anterior descending coronary artery (LAD) to pacing leads in these positions. We retrospectively analyzed three cases in which patients with RV active-fixation leads in situ also had coronary angiography. Multiple fluoroscopic views were used to determine the relationship of the lead tip at various pacing sites to the coronary arteries. A lead placed on the anterior wall was in close proximity to the LAD, whereas septal and free wall positioning was not. Placement of RV active-fixation leads on the septum avoids potential coronary artery compromise.

Is there a right place to pace the right ventricle? Evaluation of apical and septal positions in a pacemaker population: study protocol for a prospective intervention-control trial.

PubMed

Muto, Carmine; Calvi, Valeria; Botto, Giovanni Luca; Pecora, Domenico; Ciaramitaro, Gianfranco; Valsecchi, Sergio; Malacrida, Maurizio; Maglia, Giampiero

2014-11-01

The main objective of research in pacemaker therapy has been to provide the best physiologic way to pace the heart. Despite the good results provided by right ventricular pacing minimization and by biventricular pacing in specific subsets of heart failure patients, these options present many limitations for standard pacemaker recipients. In these patients, pacing the right ventricle at alternative sites could result in a lower degree of left intraventricular dyssynchrony. Despite the lack of strong evidence and the difficulty in placing and accurately classifying the final lead position, pacing at alternative right ventricular sites seems to have become a standard procedure at many implanting centers. The RIGHT PACE study is a multi-center, prospective, single-blind, double-arm, intervention-control trial comparing right ventricular pacing from the apex and from the septal site in terms of left intraventricular dyssynchrony. A total of 408 patients with indications for cardiac pacing but without indications for ICD and/or CRT will be enrolled. Investigators will be divided on the basis of their prior experience of selective site pacing lead implantation and patients will be treated according to the clinical practice of the centers. After device implantation, they will be followed up for 24 months through evaluation of clinical, echocardiographic and safety/system-performance variables. This study might provide important information about the impact of the right ventricular pacing on the left ventricular dyssynchrony, and about acute and chronic responses to selective site pacing, as adopted in current clinical practice. This trial is registered at ClinicalTrials.gov (ID:NCT01647490). Right Ventricular Lead Placement in a Pacemaker Population: Evaluation of apical and alternative position. ClinicalTrials.gov: NCT01647490. Copyright © 2014 Elsevier Inc. All rights reserved.

The Use of Epicardial Electrogram as a Simple Guide to Select the Optimal Site of Left Ventricular Pacing in Cardiac Resynchronization Therapy

PubMed Central

Fatemi, Marjaneh; Le Gal, Grégoire; Blanc, Jean-Jacques; Mansourati, Jacques; Etienne, Yves

2011-01-01

Cardiac resynchronization therapy (CRT) has been demonstrated to improve symptoms and survival in patients with left ventricular (LV) systolic dysfunction and dyssynchrony. To achieve this goal, the LV lead should be positioned in a region of delayed contraction. We hypothesized that pacing at the site of late electrical activation was also associated with long-term response to CRT. We conducted a retrospective study on 72 CRT patients. For each patient, we determined the electrical delay (ED) from the onset of QRS to the epicardial EGM and the ratio of ED to QRS duration (ED/QRS duration). After a followup of 30 ± 20 months, 47 patients responded to CRT. Responders had a significantly longer ED and greater ratio of ED/QRS duration than nonresponders. An ED/QRS duration ≥0.38 predicted a response to CRT with 89% specificity and 53% sensitivity. PMID:21403903

Minimally invasive surgical implantation of left ventricular epicardial leads for ventricular resynchronization using video-assisted thoracoscopy.

PubMed

Fernández, Angel L; García-Bengochea, José B; Ledo, Ramiro; Vega, Marino; Amaro, Antonio; Alvarez, Julián; Rubio, José; Sierra, Juan; Sánchez, Daniel

2004-04-01

Cardiac resynchronization via left ventricular or biventricular pacing is an option for selected patients with ventricular systolic dysfunction and widened QRS complex. Stimulation through a coronary vein is the technique of choice for left ventricular pacing, but this approach results in a failure rate of approximately 8%. We describe our initial experience with minimally invasive surgical implantation of left ventricular epicardial leads using video-assisted thoracoscopy. A total of 14 patients with congestive heart failure, NYHA functional class 3.2 (0.6) and mean ejection fraction 22.9 (6.8)% were included in this study. Left bundle branch block, QRS complex >140 ms and abnormal septal motion were observed in all cases. Epicardial leads were implanted on the left ventricular free wall under general anesthesia using video-assisted thoracoscopic surgery. Lead implantation was successful in 13 patients. Conversion to a small thoracotomy was necessary in one patient. All patients were extubated in the operating room. None of the patients died during their hospital stay. Follow-up showed reversal of ventricular asynchrony and significant improvement in ejection fraction and functional class. Minimally invasive surgery for ventricular resynchronization using video-assisted thoracoscopy in selected patients is a safe procedure that makes it possible to choose the best site for lead implantation and provides adequate short- and medium-term stimulation.

Bachmann bundle pacing reduces atrial electromechanical delay in type 1 myotonic dystrophy patients.

PubMed

Russo, Vincenzo; Rago, Anna; Papa, Andrea Antonio; Arena, Giulia; Politano, Luisa; Nigro, Gerardo

2018-04-01

Atrial electromechanical delay (AEMD) is an echocardiographic parameter correlated with the onset of supraventricular arrhythmias in several clinical conditions. Inter-atrial septal pacing in the region of Bachmann's bundle (BB) has been shown to be safe and feasible in myotonic dystrophy type 1 (DM1) patients, with a low rate of sensing and pacing defects. The aim of this study was to assess the impact of temporary BB pacing compared with right atrial appendage (RAA) pacing on AEMD in DM1 patients undergoing pacemaker (PM) implantation for cardiac rhythm abnormalities. The study enrolled 70 consecutive DM1 patients undergoing PM implantation for cardiac rhythm abnormalities in accordance with the current guidelines. Seventy age- and sex-matched non-DM1 patients undergoing dual-chamber PM implantation for cardiac rhythm abnormalities were used as controls. The atrial pacing lead was temporarily positioned in the RAA and on the right side of the inter-atrial septum in the region of Bachmann's bundle. For each site (BB and RAA), temporary atrial pacing in the AAI mode was established at 10 beats per minute above the sinus rate and a detailed trans-thoracic echocardiogram with tissue Doppler (TDI) analysis was recorded after at least 10 min of atrial pacing to evaluate AEMD. Temporary RAA pacing did not show statistically significant differences in inter-AEMD (48.2 ± 17.8 vs 50.5 ± 16.5 ms; P = 0.8), intra-left AEMD (43.3 ± 15.5 vs 44.6 ± 15.8 ms; P = 0.1), or intra-right-AEMD (14.1 ± 4.2 vs 15.4 ± 5.8 ms; P = 0.9), in comparison with sinus rhythm. Temporary BB pacing determined a significantly lower inter-AEMD (36.1 ± 17.1 vs 50.5 ± 16.5 ms; P = 0.001) and intra-left AEMD (32.5 ± 15.2 vs 44.6 ± 15.8 ms; P = 0.001) values in comparison with temporary RAA pacing. No statistically significant difference was found in intra-right AEMD (12.2 ± 4.6 vs 15.4 ± 5.8 ms; P = 0.2). In the control group, neither temporary RAA pacing nor temporary BB pacing showed statistically significant differences in inter-AEMD, intra-left AEMD, or intra-right AEMD values in comparison with sinus rhythm. In DM1 patients undergoing dual-chamber PM implantation, atrial pacing in the Bachmann bundle region is associated with significantly lower echocardiographic indices of atrial electromechanical delay (inter-AEMD and intra-left AEMD) in comparison with RAA pacing.

Comparison of right ventricular septal pacing and right ventricular apical pacing in patients receiving cardiac resynchronization therapy defibrillators: the SEPTAL CRT Study

PubMed Central

Leclercq, Christophe; Sadoul, Nicolas; Mont, Lluis; Defaye, Pascal; Osca, Joaquim; Mouton, Elisabeth; Isnard, Richard; Habib, Gilbert; Zamorano, Jose; Derumeaux, Genevieve; Fernandez-Lozano, Ignacio; Dupuis, Jean-Marc; Rouleau, Frédéric; Tassin, Aude; Bordachar, Pierre; Clémenty, Jacques; Lafitte, Stephane; Ploux, Sylvan; Reant, Patricia; Ritter, Philippe; Defaye, Pascal; Jacon, Peggy; Mondesert, Blandine; Saunier, Carole; Vautrin, Estelle; Kacet, Salem; Guedon-Moreau, Laurence; Klug, Didier; Kouakam, Claude; Marechaux, Sylvestre; Marquie, Christelle; Polge, Anne Sophie; Richardson, Marjorie; Chevallier, Philippe; De Breyne, Brigitte; Lotek, Marcin M.; Nonin, Emilie; Pineau, Julien; Deharo, Jean-Claude; Bastard, Emilie; Franceschi, Frédéric; Habib, Gilbert; Jego, Christophe; Peyrouse, Eric; Prevot, Sebastien; Saint-Joseph, Hôpital; Bremondy, Michel; Faure, Jacques; Ferracci, Ange; Lefevre, Jean; Pisapia, Andre; Davy, Jean-Marc; Cransac, Frederic; Cung, Tien Tri; Georger, Frederic; Pasquie, Jean-Luc; Raczka, Franck; Sportouch-Dukhan, Catherine; Sadoul, Nicolas; Blangy, Hugues; Bruntz, Jean-François; Freysz, Luc; Groben, Laurent; Huttin, Olivier; Bammert, Antoine; Burban, Marc; Cebron, Jean-Pierre; Gras, Daniel; Frank, Robert; Duthoit, Guillaume; Hidden-Lucet, Françoise; Himbert, Caroline; Isnard, Richard; Lacotte, Jérôme; Pousset, Françoise; Zerah, Thierry; Leclercq, Christophe; Bellouin, Annaïk; Crocq, Christophe; Deplace, Christian; Donal, Erwan; Hamon, Cécile; Mabo, Philippe; Romain, Olivier; Solnon, Aude; Frederic, Anselme; Bauer, Fabrice; Bernard, Mathieu; Godin, Benedicte; Kurtz, Baptiste; Savoure, Arnaud; Copie, Xavier; Lascault, Gilles; Paziaud, Olivier; Piot, Olivier; Touche, Thierry; Delay, Toulouse Marc; Chilon, Talia; Detis, Nicolas; Duparc, Alexandre; Hebrard, Aurélien; Massabuau, Pierre; Maury, Philippe; Mondoly, Pierre; Rumeau, Philippe; Pasteur, Clinique; Boveda, Serge; Adrover, Laurence; Combes, Nicolas; Deplagne, Antoine; Marco-Baertich, Isabelle; Fondard, Olivier; Martínez, Juan Gabriel; Ibañez Criado, José Luis; Ortuño, Diego; Mont, Lluis; Berruezo, Antonio; Eduard, Belu; Martín, Ana; Merschon, Franco M.; Sitges, Marta; Tolosana, José María; Vidal, Bárbara; Hebron, H. Valle; i Mitjans, Angel Moya; Rodriguez, Oscar Alcalde; Rodriguez Palomares, José Fernando; Rivas, Nuria; Teixidó, Gisela; de Hierro, H. Puerta; Lozano, Ignacio Fernández; Ruiz Bautista, Maria Lorena; Castro, Victor; Cavero, Miguel Angel; Gutierrez, Carlos; Ros, Natalia; de la Victoria, H. Virgen; Alzueta Rodriguez, Francisco Javier; Cabrera, Fernando; Cordero, Alberto Barrera; Peña, José Luis; de Valme Sevilla, H.; Gonzáles, Juan Lealdel Ojo; Garcia Medina, Mª Dolores; Jiménez, Ricardo Pavón; Villagomez, David; de la Salud Toledo, H. Virgen; Castellanos Martinez, Eduardo; Alcalá, Juan; Maicas, Carolina; Arias Palomares, Miguel Angel; Puchol, Alberto; Valencia, H. La Fé; OscaAsensi, Joaquim; Carmona, Anastasio Quesada; De Carranza, Mª José Sancho-Tello; De Ros, José Olagüe; Pareja, Enrique Castro; Pérez, Oscar Cano; Saez, Ana Osa; Hortega, H. Rio; Guilarte, Benito Herreros; Muñoz San Jose, Juan Francisco; Pérez Sanz, Teresa Myriam; Logeart, Damien; Gil, Maria Lopez; Leclercq, Christophe; Lozano, Ignacio Fernandez; de Hierro, H. Puerta; Derumeaux, Genevieve

2016-01-01

Abstract Aims Cardiac resynchronization therapy (CRT) is a recommended treatment of heart failure (HF) patients with depressed left ventricular ejection fraction and wide QRS. The optimal right ventricular (RV) lead position being a matter of debate, we sought to examine whether RV septal (RVS) pacing was not inferior to RV apical (RVA) pacing on left ventricular reverse remodelling in patients receiving a CRT-defibrillator. Methods and results Patients (n = 263, age = 63.4 ± 9.5 years) were randomly assigned in a 1:1 ratio to RVS (n = 131) vs. RVA (n = 132) pacing. Left ventricular end-systolic volume (LVESV) reduction between baseline and 6 months was not different between the two groups (−25.3 ± 39.4 mL in RVS group vs. −29.3 ± 44.5 mL in RVA group, P = 0.79). Right ventricular septal pacing was not non-inferior (primary endpoint) to RVA pacing with regard to LVESV reduction (average difference = −4.06 mL; P = 0.006 with a −20 mL non-inferiority margin). The percentage of ‘echo-responders’ defined by LVESV reduction >15% between baseline and 6 months was similar in both groups (50%) with no difference in the time to first HF hospitalization or death (P = 0.532). Procedural or device-related serious adverse events occurred in 68 patients (RVS = 37) with no difference between the two groups (P = 0.401). Conclusion This study demonstrates that septal RV pacing in CRT is non-inferior to apical RV pacing for LV reverse remodelling at 6 months with no difference in the clinical outcome. No recommendation for optimal RV lead position can hence be drawn from this study. ClinicalTrials. gov number NCT 00833352. PMID:26374852

DDD(R)-pacing, but not AAI(R)-pacing induces left ventricular desynchronization in patients with sick sinus syndrome: tissue-Doppler and 3D echocardiographic evaluation in a randomized controlled comparison.

PubMed

Albertsen, Andi Eie; Nielsen, Jens Cosedis; Poulsen, Steen Hvitfeldt; Mortensen, Peter Thomas; Pedersen, Anders Kirstein; Hansen, Peter Steen; Jensen, Henrik Kjaerulf; Egeblad, Henrik

2008-02-01

Increasing evidence from randomized trials and experimental studies indicates that right ventricular (RV) pacing may induce congestive heart failure. We studied regional left ventricular (LV) dyssynchrony and global LV function in 50 consecutive patients with sick sinus syndrome (SSS) randomized to either atrial pacing [AAI(R)] or dual chamber RV-pacing [DDD(R)]. Fifty consecutive patients were randomized to AAI(R) or DDD(R)-pacing. Tissue-Doppler imaging was used to quantify LV dyssynchrony in terms of number of segments with delayed longitudinal contraction (DLC). Left ventricular ejection fraction (LVEF) was measured using three-dimensional echocardiography. Dyssynchrony was more pronounced in the DDD(R)-group than in the AAI(R)-group at the 12 months follow-up (P < 0.05). This reflected a significant increase of dyssynchrony in the DDD(R)-group from baseline to the 12 months follow-up (1.3 +/- 1 to 2.1 +/- 1 segments displaying DLC per patient), P < 0.05. No change was observed in the AAI(R)-group (1.6 +/- 2 to 1.3 +/- 2 segments displaying DLC per patient, NS). No difference in LVEF, NYHA or NT-proBNP was observed between AAI(R)- and DDD(R)-mode after 12 months of pacing although LVEF decreased significantly in the DDD(R)-group from baseline (63.1 +/- 8%) to the 12 months follow-up (59.3 +/- 8%, P < 0.05), while LVEF remained unchanged in the AAI(R)-group (61.5 +/- 11% at baseline vs. 62.3 +/- 7% after 12 months, NS. In patients with SSS, DDD(R)-pacing but not AAI(R)-pacing induces significant LV desynchronization and reduction of LVEF.

Comparison of right ventricular septal pacing and right ventricular apical pacing in patients receiving cardiac resynchronization therapy defibrillators: the SEPTAL CRT Study.

PubMed

Leclercq, Christophe; Sadoul, Nicolas; Mont, Lluis; Defaye, Pascal; Osca, Joaquim; Mouton, Elisabeth; Isnard, Richard; Habib, Gilbert; Zamorano, Jose; Derumeaux, Genevieve; Fernandez-Lozano, Ignacio

2016-02-01

Cardiac resynchronization therapy (CRT) is a recommended treatment of heart failure (HF) patients with depressed left ventricular ejection fraction and wide QRS. The optimal right ventricular (RV) lead position being a matter of debate, we sought to examine whether RV septal (RVS) pacing was not inferior to RV apical (RVA) pacing on left ventricular reverse remodelling in patients receiving a CRT-defibrillator. Patients (n = 263, age = 63.4 ± 9.5 years) were randomly assigned in a 1:1 ratio to RVS (n = 131) vs. RVA (n = 132) pacing. Left ventricular end-systolic volume (LVESV) reduction between baseline and 6 months was not different between the two groups (-25.3 ± 39.4 mL in RVS group vs. -29.3 ± 44.5 mL in RVA group, P = 0.79). Right ventricular septal pacing was not non-inferior (primary endpoint) to RVA pacing with regard to LVESV reduction (average difference = -4.06 mL; P = 0.006 with a -20 mL non-inferiority margin). The percentage of 'echo-responders' defined by LVESV reduction >15% between baseline and 6 months was similar in both groups (50%) with no difference in the time to first HF hospitalization or death (P = 0.532). Procedural or device-related serious adverse events occurred in 68 patients (RVS = 37) with no difference between the two groups (P = 0.401). This study demonstrates that septal RV pacing in CRT is non-inferior to apical RV pacing for LV reverse remodelling at 6 months with no difference in the clinical outcome. No recommendation for optimal RV lead position can hence be drawn from this study. NCT 00833352. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.

Single-site ventricular pacing via the coronary sinus in patients with tricuspid valve disease.

PubMed

Noheria, Amit; van Zyl, Martin; Scott, Luis R; Srivathsan, Komandoor; Madhavan, Malini; Asirvatham, Samuel J; McLeod, Christopher J

2018-04-01

To evaluate coronary sinus single-site (CSSS) left ventricular pacing in adult patients with normal left ventricular ejection fraction (LVEF) when traditional right ventricular lead implantation is not feasible or is contraindicated. We performed a retrospective analysis of 23 patients with tricuspid valve surgery/disease who received a CSSS ventricular pacing lead to avoid crossing the tricuspid valve. Two matched control populations were obtained from patients receiving (i) conventional right ventricular single-site (RVSS) leads and (ii) coronary sinus leads for cardiac resynchronization therapy (CSCRT). Main outcomes of interest were lead stability, electrical lead parameters and change in LVEF during long-term follow-up. Successful CSSS pacing was accomplished in all 23 patients without any procedural complications. During the 5.3 ± 2.8-year follow-up 22/23 (95.7%) leads were functional with stable pacing and sensing parameters, and 1/23 (4.3%) was extracted for unrelated reasons. Compared to CSSS leads, the lead revision/abandonment was similar with RVSS leads (Hazard ratio (HR) 0.87, 95% confidence interval (CI) 0.03, 22.0), but was higher with CSCRT leads (HR 7.41, 95% CI 1.30, 139.0). There was no difference in change in LVEF between CSSS and RVSS groups (-2.4 ± 11.0 vs. 1.5 ± 12.8, P = 0.76), but LVEF improved in CSCRT group (11.2 ± 16.5%, P = 0.002). Fluoroscopy times were longer during implantation of CSSS compared to RVSS leads (25.6 ± 24.6 min vs. 12.3 ± 18.6 min, P = 0.049). In patients with normal LVEF, single-site ventricular pacing via the coronary sinus is a feasible, safe and reliable alternative to right ventricular pacing.

The effect of different atrioventricular delays on left atrium and left atrial appendage function in patients with DDD pacemaker.

PubMed

Kanadaşı, Mehmet; Caylı, Murat; Sahin, Durmuş Yıldıray; Sen, Ömer; Koç, Mevlüt; Usal, Ayhan; Batur, Mustafa Kemal; Demirtaş, Mustafa

2011-07-01

Although it has been known that optimization of atrioventricular delay (AVD) has favorable effect on the left ventricular functions in patients with DDD pacemaker, the effect of different AVDs on left atrium (LA) and left atrial appendage (LAA) functions has not been exactly evaluated. The aim of the present study was to assess the effect of different AVDs on LA and LAA functions in DDD pacemaker implanted patients with atrioventricular block. Forty-eight patients with DDD pacemaker were enrolled into the study. Patients were divided into two groups according to the echocardiographic diastolic function: Group I (normal diastolic function) and Group II (diastolic dysfunction). LAA emptying velocity on pulsed wave Doppler and LAA late systolic wave velocity by using tissue Doppler were recorded. Patients were paced for five successive continuous pacing periods of 10 minutes duration using five selective AVDs (80-250 ms). Significant effect on LA and LAA functions has not been observed by the setting of AVD in Group I. However, when the AVD was gradually shortened form 150 ms to 80 ms, LA and LAA functions gradually decreased in Group II patients. When AVD increased to 200 ms, LA and LAA functions were improved. Further increase in AVD resulted in decreased LA and LAA functions. Setting of AVD has not significant effect on the LA and LAA functions in patients with normal diastolic function, but moderate prolongation of AVD in physiological limits improved LA and LAA functions in DDD pacemaker implanted patients with diastolic dysfunction. © 2011, Wiley Periodicals, Inc.

Tailor-made heart simulation predicts the effect of cardiac resynchronization therapy in a canine model of heart failure.

PubMed

Panthee, Nirmal; Okada, Jun-ichi; Washio, Takumi; Mochizuki, Youhei; Suzuki, Ryohei; Koyama, Hidekazu; Ono, Minoru; Hisada, Toshiaki; Sugiura, Seiryo

2016-07-01

Despite extensive studies on clinical indices for the selection of patient candidates for cardiac resynchronization therapy (CRT), approximately 30% of selected patients do not respond to this therapy. Herein, we examined whether CRT simulations based on individualized realistic three-dimensional heart models can predict the therapeutic effect of CRT in a canine model of heart failure with left bundle branch block. In four canine models of failing heart with dyssynchrony, individualized three-dimensional heart models reproducing the electromechanical activity of each animal were created based on the computer tomographic images. CRT simulations were performed for 25 patterns of three ventricular pacing lead positions. Lead positions producing the best and the worst therapeutic effects were selected in each model. The validity of predictions was tested in acute experiments in which hearts were paced from the sites identified by simulations. We found significant correlations between the experimentally observed improvement in ejection fraction (EF) and the predicted improvements in ejection fraction (P<0.01) or the maximum value of the derivative of left ventricular pressure (P<0.01). The optimal lead positions produced better outcomes compared with the worst positioning in all dogs studied, although there were significant variations in responses. Variations in ventricular wall thickness among the dogs may have contributed to these responses. Thus CRT simulations using the individualized three-dimensional heart models can predict acute hemodynamic improvement, and help determine the optimal positions of the pacing lead. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of right ventricular pacing lead site on left ventricular function in patients with high-grade atrioventricular block: results of the Protect-Pace study.

PubMed

Kaye, Gerald C; Linker, Nicholas J; Marwick, Thomas H; Pollock, Lucy; Graham, Laura; Pouliot, Erika; Poloniecki, Jan; Gammage, Michael

2015-04-07

Chronic right ventricle (RV) apical (RVA) pacing is standard treatment for an atrioventricular (AV) block but may be deleterious to left ventricle (LV) systolic function. Previous clinical studies of non-apical pacing have produced conflicting results. The aim of this randomized, prospective, international, multicentre trial was to compare change in LV ejection fraction (LVEF) between right ventricular apical and high septal (RVHS) pacing over a 2-year study period. We randomized 240 patients (age 74 ± 11 years, 67% male) with a high-grade AV block requiring >90% ventricular pacing and preserved baseline LVEF >50%, to receive pacing at the RVA (n = 120) or RVHS (n = 120). At 2 years, LVEF decreased in both the RVA (57 ± 9 to 55 ± 9%, P = 0.047) and the RVHS groups (56 ± 10 to 54 ± 10%, P = 0.0003). However, there was no significant difference in intra-patient change in LVEF between confirmed RVA (n = 85) and RVHS (n = 83) lead position (P = 0.43). There were no significant differences in heart failure hospitalization, mortality, the burden of atrial fibrillation, or plasma brain natriutetic peptide levels between the two groups. A significantly greater time was required to place the lead in the RVHS position (70 ± 25 vs. 56 ± 24 min, P < 0.0001) with longer fluoroscopy times (11 ± 7 vs. 5 ± 4 min, P < 0.0001). In patients with a high-grade AV block and preserved LV function requiring a high percentage of ventricular pacing, RVHS pacing does not provide a protective effect on left ventricular function over RVA pacing in the first 2 years. ClinicalTrials.gov number NCT00461734. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Understanding nonresponders of cardiac resynchronization therapy--current and future perspectives.

PubMed

Yu, Cheuk-Man; Wing-Hong Fung, Jeffrey; Zhang, Qing; Sanderson, John E

2005-10-01

Cardiac resynchronization therapy (CRT) is now an established nonpharmacologic therapy for advanced heart failure with electromechanical delay. Despite compelling evidence of the benefits of CRT, one troubling issue is the lack of a favorable response in about one-third of patients. Currently, there is no unifying definition of responders, and published data were based on acute hemodynamic changes, chronic left ventricular reverse remodeling, as well as the intermediate or long-term clinical response. The lack of improvement with CRT can be due to many factors including the placement of the left ventricular pacing lead in an inappropriate location, the absence of electrical conduction delay or mechanical dyssynchrony despite wide QRS complexes, and possibly failure to optimize the CRT settings after device implantation. In acute hemodynamic studies, placing the left ventricular leads at the free wall region has been suggested to generate the best pulse pressure and positive dp/dt. The degree of mechanical dyssynchrony has recently been assessed noninvasively in CRT patients by echocardiography and in particular by tissue Doppler imaging. These studies suggested that responders of left ventricular reverse remodeling or systolic function had more severe systolic dyssynchrony. However, further studies are needed to examine the clinical utility of these parameters when applied to the standardized anatomic or functional endpoints. Optimization of atrioventricular and interventricular pacing intervals may also reduce the number of nonresponders, though newer methods, especially interventricular pacing intervals, are still under clinical investigation. With the adjunctive use of imaging technology, physicians are able to characterize the response to CRT objectively, and cardiac imaging is an important clinical tool for determining more precisely the presence and degree of mechanical dyssynchrony.

Impact of No Child Left Behind on English Language Learners. Hearing before the Subcommittee on Early Childhood Elementary and Secondary Education of the Committee on Education and Labor. U.S. House of Representatives. One Hundred Tenth Congress, First Session (March 23, 2007). Serial Number 110-14

ERIC Educational Resources Information Center

US House of Representatives, 2007

2007-01-01

This document records testimony regarding the Department of Education's slow pace in providing States the assistance they require to implement No Child Left Behind's provisions for English Language Learners (ELLs) and the status of recent efforts to correct that; practices for training teachers of ELL students and for improving their academic…

Influence of automatic frequent pace-timing adjustments on effective left ventricular pacing during cardiac resynchronization therapy.

PubMed

Varma, Niraj; Stadler, Robert W; Ghosh, Subham; Kloppe, Axel

2017-05-01

Cardiac resynchronization therapy (CRT) requires effective left ventricular (LV) pacing (i.e. sufficient energy and appropriate timing to capture). The AdaptivCRT™ (aCRT) algorithm serves to maintain ventricular fusion during LV or biventricular pacing. This function was tested by comparing the morphological consistency of ventricular depolarizations and percentage effective LV pacing in CRT patients randomized to aCRT vs. echo-optimization. Continuous recordings (≥20 h) of unipolar LV electrograms from aCRT (n = 38) and echo-optimized patients (n = 22) were analysed. Morphological consistency was determined by the correlation coefficient between each beat and a template beat. Effective LV pacing of paced beats was assessed by algorithmic analysis of negative initial EGM deflection in each evoked response. The %CRT pacing delivered, %effective LV pacing (i.e. % of paced beats with effective LV pacing), and overall %effective CRT (i.e. product of %CRT pacing and %effective LV pacing) were compared between aCRT and echo-optimized patients. Demographics were similar between groups. The mean correlation coefficient between individual beats and template was greater for aCRT (0.96 ± 0.03 vs. 0.91 ± 0.13, P = 0.07). Although %CRT pacing was similar for aCRT and echo-optimized (median 97.4 vs. 98.6%, P = 0.14), %effective LV pacing was larger for aCRT [99.6%, (99.1%, 99.9%) vs. 94.3%, (24.3%, 99.8%), P=0.03]. For aCRT vs. echo-optimized groups, the proportions of patients with ≥90% effective LV pacing was 92 vs. 55% (P = 0.002), and with ≥90% effective CRT was 79 vs. 45%, respectively (P = 0.018). AdaptivCRT™ significantly increased effective LV pacing over echo-optimized CRT. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Functional characteristics of left ventricular synchronization via right ventricular outflow-tract pacing detected by two-dimensional strain echocardiography.

PubMed

Hirayama, Yasutaka; Kawamura, Yuichiro; Sato, Nobuyuki; Saito, Tatsuya; Tanaka, Hideichi; Saijo, Yasuaki; Kikuchi, Kenjiro; Ohori, Katsumi; Hasebe, Naoyuki

2017-02-01

Recently, due to the detrimental effects on the ventricular function associated with right ventricular apical (RVA) pacing, right ventricular septal (RVS) pacing has become the preferred pacing method. However, the term RVS pacing refers to both right ventricular outflow-tract (RVOT) and mid-septal (RVMS) pacing, leading to a misinterpretation of the results of clinical studies. The purpose of this study, therefore, was to elucidate the functional differences of RVA, RVOT, and RVMS pacing in patients with atrioventricular block. We compared the QRS duration, global longitudinal strain (GLS), and left ventricular (LV) synchronization parameters at the three pacing sites in 47 patients. The peak systolic strain (PSS) time delay between the earliest and latest segments among the 18 LV segments and standard deviation (SD) of the time to the PSS were also calculated for the 18 LV segments at each pacing site using two-dimensional (2D) strain echocardiography. RVMS pacing was associated with a significantly shorter QRS duration compared with RVA and RVOT pacing (154.4±21.4 vs 186.5±19.9 and 171.1±21.5 ms, P <0.001). In contrast, RVOT pacing revealed a greater GLS (-14.69±4.92 vs -13.12±4.76 and -13.51±4.81%, P <0.001), shorter PSS time delay between the earliest and latest segments (236.0±87.9 vs 271.3±102.9 and 281.9±126.6%, P =0.007), and shorter SD of the time to the PSS (70.8±23.8 vs 82.7±30.8 and 81.5±33.7 ms, P =0.002) compared with RVA and RVMS pacing. These results suggest that the functional characteristics of RVOT pacing may be a more optimal pacing site than RVMS, regardless of the pacing QRS duration, in patients with atrioventricular conduction disorders.

Implantable cardiac arrhythmia devices--part I: pacemakers.

PubMed

Kusumoto, Fred M; Goldschlager, Nora

2006-05-01

Implantable cardiac devices have become firmly entrenched as important therapeutic tools for a variety of cardiac conditions. The first part of this two-part review will discuss the contemporary use and follow-up of pacemakers, while the second part will address the use of implantable cardioverter defibrillators and implantable loop recorders. Pacemakers are the only available treatment for symptomatic bradycardia not due to reversible causes. Large randomized studies have demonstrated a small but statistically significant reduction in atrial fibrillation associated with pacing modes that maintain atrioventricular synchrony. In contrast, pacing mode appears to have a less dramatic effect in patients with atrioventricular block. Cardiac resynchronization with specialized left ventricular leads has been shown to reduce symptoms and improve survival in patients with symptomatic heart failure, systolic dysfunction, and widened QRS complexes. For all patients, careful follow-up is necessary to ensure optimal therapeutic benefit of pacing systems.

Effects of simultaneous and optimized sequential cardiac resynchronization therapy on myocardial oxidative metabolism and efficiency.

PubMed

Christenson, Stuart D; Chareonthaitawee, Panithaya; Burnes, John E; Hill, Michael R S; Kemp, Brad J; Khandheria, Bijoy K; Hayes, David L; Gibbons, Raymond J

2008-02-01

Cardiac resynchronization therapy (CRT) can improve left ventricular (LV) hemodynamics and function. Recent data suggest the energy cost of such improvement is favorable. The effects of sequential CRT on myocardial oxidative metabolism (MVO(2)) and efficiency have not been previously assessed. Eight patients with NYHA class III heart failure were studied 196 +/- 180 days after CRT implant. Dynamic [(11)C]acetate positron emission tomography (PET) and echocardiography were performed after 1 hour of: 1) AAI pacing, 2) simultaneous CRT, and 3) sequential CRT. MVO(2) was calculated using the monoexponential clearance rate of [(11)C]acetate (k(mono)). Myocardial efficiency was expressed in terms of the work metabolic index (WMI). P values represent overall significance from repeated measures analysis. Global LV and right ventricular (RV) MVO(2) were not significantly different between pacing modes, but the septal/lateral MVO(2) ratio differed significantly with the change in pacing mode (AAI pacing = 0.696 +/- 0.094 min(-1), simultaneous CRT = 0.975 +/- 0.143 min(-1), and sequential CRT = 0.938 +/- 0.189 min(-1); overall P = 0.001). Stroke volume index (SVI) (AAI pacing = 26.7 +/- 10.4 mL/m(2), simultaneous CRT = 30.6 +/- 11.2 mL/m(2), sequential CRT = 33.5 +/- 12.2 mL/m(2); overall P < 0.001) and WMI (AAI pacing = 3.29 +/- 1.34 mmHg*mL/m(2)*10(6), simultaneous CRT = 4.29 +/- 1.72 mmHg*mL/m(2)*10(6), sequential CRT = 4.79 +/- 1.92 mmHg*mL/m(2)*10(6); overall P = 0.002) also differed between pacing modes. Compared with simultaneous CRT, additional changes in septal/lateral MVO(2), SVI, and WMI with sequential CRT were not statistically significant on post hoc analysis. In this small selected population, CRT increases LV SVI without increasing MVO(2), resulting in improved myocardial efficiency. Additional improvements in LV work, oxidative metabolism, and efficiency from simultaneous to sequential CRT were not significant.

Relationship between left atrium catheter contact force and pacing threshold.

PubMed

Barrio-López, Teresa; Ortiz, Mercedes; Castellanos, Eduardo; Lázaro, Carla; Salas, Jefferson; Madero, Sergio; Almendral, Jesús

2017-08-01

The purpose of this study is to analyze the relationship between contact force (CF) and pacing threshold in left atrium (LA). Six to ten LA sites were studied in 28 consecutive patients with atrial fibrillation undergoing pulmonary vein isolation. Median CF, bipolar and unipolar electrogram voltage, impedance, and bipolar and unipolar thresholds for consistent constant capture and for consistent intermittent capture were measured at each site. Pacing threshold measurements were performed at 188 LA sites. Both unipolar and bipolar pacing thresholds correlated significantly with median CF; however, unipolar pacing threshold correlated better (unipolar: Pearson R -0.45; p < 0.001; Spearman Rho -0.62; p < 0.001, bipolar: Pearson R -0.39; p < 0.001; Spearman Rho -0.52; p < 0.001). Consistent constant capture threshold had better correlation with median CF than consistent intermittent capture threshold for both unipolar and bipolar pacing (Pearson R -0.45; p < 0.001 and Spearman Rho -0.62; p < 0.001 vs. Pearson R -0.35; p < 0.001; Spearman Rho -0.52; p < 0.001). The best pacing threshold cutoff point to detect a good CF (>10 g) was 3.25 mA for unipolar pacing with 69% specificity and 73% sensitivity. Both increased to 80% specificity and 74% sensitivity for sites with normal bipolar voltage and a pacing threshold cutoff value of 2.85 mA. Pacing thresholds correlate with CF in human not previously ablated LA. Since the combination of a normal bipolar voltage and a unipolar pacing threshold <2.85 mA provide reasonable parameters of validity, pacing threshold could be of interest as a surrogate for CF in LA.

A Step Forward or a Step Back? State Accountability in the Waiver Era

ERIC Educational Resources Information Center

Hall, Daria

2013-01-01

In 2002, No Child Left Behind ushered in sweeping changes in school accountability. Diverging from the federal government's long history of leaving this matter largely to the states, a Congress broadly dissatisfied with the slow pace of educational improvement stepped in with a new framework designed to set schools on a path to getting all…

Triple-site pacing for cardiac resynchronization in permanent atrial fibrillation - Acute phase results from a prospective observational study.

PubMed

Marques, Pedro; Nobre Menezes, Miguel; Lima da Silva, Gustavo; Bernardes, Ana; Magalhães, Andreia; Cortez-Dias, Nuno; Carpinteiro, Luís; de Sousa, João; Pinto, Fausto J

2016-06-01

Multi-site pacing is emerging as a new method for improving response to cardiac resynchronization therapy (CRT), but has been little studied, especially in patients with atrial fibrillation. We aimed to assess the effects of triple-site (Tri-V) vs. biventricular (Bi-V) pacing on hemodynamics and QRS duration. This was a prospective observational study of patients with permanent atrial fibrillation and ejection fraction <40% undergoing CRT implantation (n=40). One right ventricular (RV) lead was implanted in the apex and another in the right ventricular outflow tract (RVOT) septal wall. A left ventricular (LV) lead was implanted in a conventional venous epicardial position. Cardiac output (using the FloTrac™ Vigileo™ system), mean QRS and ejection fraction were calculated. Mean cardiac output was 4.81±0.97 l/min with Tri-V, 4.68±0.94 l/min with RVOT septal and LV pacing, and 4.68±0.94 l/min with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV). Mean pre-implantation QRS was 170±25 ms, 123±18 ms with Tri-V, 141±25 ms with RVOT septal pacing and LV pacing and 145±19 with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV and pre-implantation). Mean ejection fraction was significantly higher with Tri-V (30±11%) vs. Bi-V pacing (28±12% with RVOT septal and LV pacing and 28±11 with RV apical and LV pacing) and pre-implantation (25±8%). Tri-V pacing produced higher cardiac output and shorter QRS duration than Bi-V pacing. This may have a significant impact on the future of CRT. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Effects of generation mode in fMRI adaptations of semantic fluency: Paced production and overt speech

PubMed Central

Basho, Surina; Palmer, Erica D.; Rubio, Miguel A.; Wulfeck, Beverly; Müller, Ralph-Axel

2007-01-01

Verbal fluency is a widely used neuropsychological paradigm. In fMRI implementations, conventional unpaced (self-paced) versions are suboptimal due to uncontrolled timing of responses, and overt responses carry the risk of motion artifact. We investigated the behavioral and neurofunctional effects of response pacing and overt speech in semantic category-driven word generation. Twelve right-handed adults (8 female) ages 21–37 were scanned in four conditions each: Paced-Overt, Paced-Covert, Unpaced-Overt, and Unpaced-Covert. There was no significant difference in the number of exemplars generated between overt versions of the paced and unpaced conditions. Imaging results for category-driven word generation overall showed left-hemispheric activation in inferior frontal cortex, premotor cortex, cingulate gyrus, thalamus, and basal ganglia. Direct comparison of generation modes revealed significantly greater activation for the paced compared to unpaced conditions in right superior temporal, bilateral middle frontal, and bilateral anterior cingulate cortex, including regions associated with sustained attention, motor planning, and response inhibition. Covert (compared to overt) conditions showed significantly greater effects in right parietal and anterior cingulate, as well as left middle temporal and superior frontal regions. We conclude that paced overt paradigms are useful adaptations of conventional semantic fluency in fMRI, given their superiority with regard to control over and monitoring of behavioral responses. However, response pacing is associated with additional non-linguistic effects related to response inhibition, motor preparation, and sustained attention. PMID:17292926

Risk Stratification of Future Left Ventricular Dysfunction for Patients with Indications for Right Ventricular Pacing due to Bradycardia.

PubMed

Ooka, Junichi; Tanaka, Hidekazu; Hatani, Yutaka; Hatazawa, Keiko; Matsuzoe, Hiroki; Shimoura, Hiroyuki; Sano, Hiroyuki; Sawa, Takuma; Motoji, Yoshiki; Mochizuki, Yasuhide; Ryo-Koriyama, Keiko; Matsumoto, Kensuke; Fukuzawa, Koji; Hirata, Ken-Ichi

2017-10-21

Although right ventricular (RV) pacing is the only effective treatment for patients with symptomatic bradycardia, it creates left ventricular (LV) dyssynchrony, which can induce LV dysfunction and heart failure. The current criterion for consideration of cardiac resynchronization therapy (CRT) is LV ejection fraction (LVEF) ≤ 35%, but indication for CRT in patients required for RV pacing with LVEF > 35% remains unclear.We studied 40 patients, all LVEF ≥ 35%, who had undergone implantable cardioverter-defibrillator implantation with RV pacing < 5%. Echocardiography was performed at baseline and during RV pacing. LV dyssynchrony was defined as anteroseptal-to-posterior wall delay from the mid-LV short-axis view using two-dimensional speckle-tracking radial strain (significant: ≥ 130 ms). Patients were divided into two groups based on baseline LVEF: normal LVEF ( ≥ 50%; n = 20) and mildly reduced LVEF (35-50%; n = 20).LVEF and LV dyssynchrony in patients with mildly reduced LVEF deteriorated significantly during RV pacing compared to those in patients with normal LVEF. Moreover, changes in LV dyssynchrony during RV pacing significantly correlated with changes in LVEF (r = -0.44, P < 0.01). Multivariate logistic regression analysis showed that baseline LVEF was the only independent predictor and baseline LVEF < 48% predictive of significant LV dyssynchrony during RV pacing.The extent of RV pacing-induced LV dysfunction may be associated with baseline LV function. These adverse effects on patients with mildly reduced LVEF of 35-50% and indications for RV pacing due to bradycardia can thus be prevented by CRT.

Subclavian vein pacing and venous pressure waveform measurement for phrenic nerve monitoring during cryoballoon ablation of atrial fibrillation.

PubMed

Ghosh, Justin; Singarayar, Suresh; Kabunga, Peter; McGuire, Mark A

2015-06-01

The phrenic nerves may be damaged during catheter ablation of atrial fibrillation. Phrenic nerve function is routinely monitored during ablation by stimulating the right phrenic nerve from a site in the superior vena cava (SVC) and manually assessing the strength of diaphragmatic contraction. However the optimal stimulation site, method of assessing diaphragmatic contraction, and techniques for monitoring the left phrenic nerve have not been established. We assessed novel techniques to monitor phrenic nerve function during cryoablation procedures. Pacing threshold and stability of phrenic nerve capture were assessed when pacing from the SVC, left and right subclavian veins. Femoral venous pressure waveforms were used to monitor the strength of diaphragmatic contraction. Stable capture of the left phrenic nerve by stimulation in the left subclavian vein was achieved in 96 of 100 patients, with a median capture threshold of 2.5 mA [inter-quartile range (IQR) 1.4-5.0 mA]. Stimulation of the right phrenic nerve from the subclavian vein was superior to stimulation from the SVC with lower pacing thresholds (1.8 mA IQR 1.4-3.3 vs. 6.0 mA IQR 3.4-8.0, P < 0.001). Venous pressure waveforms were obtained in all patients and attenuation of the waveform was always observed prior to onset of phrenic nerve palsy. The left phrenic nerve can be stimulated from the left subclavian vein. The subclavian veins are the optimal sites for phrenic nerve stimulation. Monitoring the femoral venous pressure waveform is a novel technique for detecting impending phrenic nerve damage. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Permanent right ventricular pacing through an anomalous left superior vena cava.

PubMed Central

Amikam, S; Lemer, J; Riss, E

1977-01-01

A persistent left superior vena cava can complicate the implantation of a transvenous pacemaker. In a patient who required a permanent pacemaker, this venous anomaly was discovered during the insertion of the electrode but it did not prevent long-term right ventricular pacing. This was achieved after the electrode had been manipulated through the coronary sinus and right atrium. A plan of management is proposed for dealing with this unexpected problem. Images PMID:601745

Randomized placebo controlled blinded study to assess valsartan efficacy in preventing left ventricle remodeling in patients with dual chamber pacemaker--Rationale and design of the trial.

PubMed

Tomasik, Andrzej; Jacheć, Wojciech; Wojciechowska, Celina; Kawecki, Damian; Białkowska, Beata; Romuk, Ewa; Gabrysiak, Artur; Birkner, Ewa; Kalarus, Zbigniew; Nowalany-Kozielska, Ewa

2015-05-01

Dual chamber pacing is known to have detrimental effect on cardiac performance and heart failure occurring eventually is associated with increased mortality. Experimental studies of pacing in dogs have shown contractile dyssynchrony leading to diffuse alterations in extracellular matrix. In parallel, studies on experimental ischemia/reperfusion injury have shown efficacy of valsartan to inhibit activity of matrix metalloproteinase-9, to increase the activity of tissue inhibitor of matrix metalloproteinase-3 and preserve global contractility and left ventricle ejection fraction. To present rationale and design of randomized blinded trial aimed to assess whether 12 month long administration of valsartan will prevent left ventricle remodeling in patients with preserved left ventricle ejection fraction (LVEF ≥ 40%) and first implantation of dual chamber pacemaker. A total of 100 eligible patients will be randomized into three parallel arms: placebo, valsartan 80 mg/daily and valsartan 160 mg/daily added to previously used drugs. The primary endpoint will be assessment of valsartan efficacy to prevent left ventricle remodeling during 12 month follow-up. We assess patients' functional capacity, blood plasma activity of matrix metalloproteinases and their tissue inhibitors, NT-proBNP, tumor necrosis factor alpha, and Troponin T. Left ventricle function and remodeling is assessed echocardiographically: M-mode, B-mode, tissue Doppler imaging. If valsartan proves effective, it will be an attractive measure to improve long term prognosis in aging population and increasing number of pacemaker recipients. ClinicalTrials.org (NCT01805804). Copyright © 2015 Elsevier Inc. All rights reserved.

Assessment of exit block following pulmonary vein isolation: far-field capture masquerading as entrance without exit block.

PubMed

Vijayaraman, Pugazhendhi; Dandamudi, Gopi; Naperkowski, Angela; Oren, Jess; Storm, Randle; Ellenbogen, Kenneth A

2012-10-01

Complete electrical isolation of pulmonary veins (PVs) remains the cornerstone of ablation therapy for atrial fibrillation. Entrance block without exit block has been reported to occur in 40% of the patients. Far-field capture (FFC) can occur during pacing from the superior PVs to assess exit block, and this may appear as persistent conduction from PV to left atrium (LA). To facilitate accurate assessment of exit block. Twenty consecutive patients with symptomatic atrial fibrillation referred for ablation were included in the study. Once PV isolation (entrance block) was confirmed, pacing from all the bipoles on the Lasso catheter was used to assess exit block by using a pacing stimulus of 10 mA at 2 ms. Evidence for PV capture without conduction to LA was necessary to prove exit block. If conduction to LA was noticed, pacing output was decreased until there was PV capture without conduction to LA or no PV capture was noted to assess for far-field capture in both the upper PVs. All 20 patients underwent successful isolation (entrance block) of all 76 (4 left common PV) veins: mean age 58 ± 9 years; paroxysmal atrial fibrillation 40%; hypertension 70%, diabetes mellitus 30%, coronary artery disease 15%; left ventricular ejection fraction 55% ± 10%; LA size 42 ± 11 mm. Despite entrance block, exit block was absent in only 16% of the PVs, suggesting persistent PV to LA conduction. FFC of LA appendage was noted in 38% of the left superior PVs. FFC of the superior vena cava was noted in 30% of the right superior PVs. The mean pacing threshold for FFC was 7 ± 4 mA. Decreasing pacing output until only PV capture (loss of FFC) is noted was essential to confirm true exit block. FFC of LA appendage or superior vena cava can masquerade as persistent PV to LA conduction. A careful assessment for PV capture at decreasing pacing output is essential to exclude FFC. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Cardiac resynchronization therapy with His bundle pacing as a method of treatment of chronic heart failure in patients with permanent atrial fibrillation and left bundle branch block.

PubMed

Boczar, Krzysztof; Sławuta, Agnieszka; Ząbek, Andrzej; Dębski, Maciej; Gajek, Jacek; Lelakowski, Jacek; Małecka, Barbara

CRT is a therapeutic option for patients with heart failure, sinus rhythm, prolonged QRS complex duration and reduced ejection fraction. We present a case of 71-year-old woman with dilated cardiomyopathy, NYHA functional class III and AF. We implanted CRT combined with direct His-bundle pacing. The indication for such a therapy was a left bundle branch block with a QRS complex of 178ms and a left ventricular EF of 15%, left ventricular end-diastolic diameter (LVEDD) of 75mm. After 8months of follow-up the LVEDD was 60mm with EF 35-40%. Copyright © 2017. Published by Elsevier Inc.

Ventricular, but not atrial, M2-muscarinic receptors increase in the canine pacing-overdrive model of heart failure.

PubMed

Wilkinson, M; Giles, A; Armour, J A; Cardinal, R

1996-01-01

To investigate the effects of heart failure induced by chronic rapid ventricular pacing (six weeks) on canine atrial and ventricular muscarinic receptors. Dogs (n = 4) were fitted with a bipolar pacing electrode connected to a Medtronic pacemaker set at 240 stimuli/min. Pacing was maintained for six weeks. Tissue samples obtained from the left atrium and ventral wall of the left ventricle were frozen at -70 degrees C. Control tissue was obtained from normal dogs (n = 6) following anesthesia and thoracotomy. M2-muscarinic receptors were characterized and quantified in tissue micropunches using the hydrophilic ligand [3H] N-methyl-scopolamine (NMS). Cardiac tissue bound [3H] NMS with the specificity of an M2 subtype. Tachycardia-induced heart failure did not affect atrial muscarinic receptors but signify left ventricular myocytes (control 160.0 +/- 10.0 fmol/mg protein versus heart failure 245.0 +/- 25.0 fmol/mg protein; P < 0.01). Canine ventricular muscarinic receptors display a specificity for the M2 subtype. In contrast to previous work, tachycardia-induced heart failure was accompanied by an increase (+ 53%) in ventricular, but not atrial, M2 receptors compared with normal dogs.

The effect of atrial pacing site on electrophysiological properties of the atrioventricular junction and induction of atrioventricular nodal reentry in patients with typical atrioventricular nodal reentrant tachycardia.

PubMed

Kiedrowicz, Radosław M; Kaźmierczak, Jarosław; Wielusiński, Maciej

2017-01-01

Clinical studies in humans have shown the site of atrial stimulation to influence atrioventricular (AV) conduction times and refractory periods, the demonstration of dual AV nodal (AVN) pathways, and induction of AVN reentry. These studies often found conflicting results. Moreover, among enrolled patients a minority of them were found to have AVN reentrant tachycardia (AVNRT). The purpose of this study was to investigate the effect of right and left atrial pacing on the electrophysiological properties of the AV junction in the typical AVNRT population. Ninety-two consecutive patients with typical AVNRT were included. Atrial pacing was performed from the high right atrium (HRA) and the left atrium via the proximal coronary sinus (CS). Stimulation from either the HRA or the CS could result in dual AVN physiology and AVNRT. No site-dependent differences in the ease of induction of dual AVN pathways with variability of initiation from either site were found. However, AVNRT was easier to induce from the HRA. With CS pacing the leftward but not the rightward AVN approaches were the entry point to the AV node because of significantly shorter AH conduction times compared to HRA pacing. Conduction over the leftward AVN extensions could initiate the tachycardia with significantly shorter critical AH interval compared to conduction over the rightward AVN extensions; however, the AH interval during AVNRT and its cycle length were not significantly different. Rightward and leftward AVN extensions are regular features of the AV node. Their different electrophysiological properties lead to variation in the demonstration of discontinuous AVN conduction and AVNRT during right and left atrial pacing. Despite the observation that the left AVN extensions could compose the entry point to the reentrant circuit, there is no evidence that they constitute the critical component of sustained typical AVNRT.

Reduction in unnecessary ventricular pacing fails to affect hard clinical outcomes in patients with preserved left ventricular function: a meta-analysis.

PubMed

Shurrab, Mohammed; Healey, Jeff S; Haj-Yahia, Saleem; Kaoutskaia, Anna; Boriani, Giuseppe; Carrizo, Aldo; Botto, Gianluca; Newman, David; Padeletti, Luigi; Connolly, Stuart J; Crystal, Eugene

2017-02-01

Several pacing modalities across multiple manufacturers have been introduced to minimize unnecessary right ventricular pacing. We conducted a meta-analysis to assess whether ventricular pacing reduction modalities (VPRM) influence hard clinical outcomes in comparison to standard dual-chamber pacing (DDD). An electronic search was performed using Cochrane Central Register, PubMed, Embase, and Scopus. Only randomized controlled trials (RCT) were included in this analysis. Outcomes of interest included: frequency of ventricular pacing (VP), incident persistent/permanent atrial fibrillation (PerAF), all-cause hospitalization and all-cause mortality. Odds ratios (OR) were reported for dichotomous variables. Seven RCTs involving 4119 adult patients were identified. Ventricular pacing reduction modalities were employed in 2069 patients: (MVP, Medtronic Inc.) in 1423 and (SafeR, Sorin CRM, Clamart) in 646 patients. Baseline demographics and clinical characteristics were similar between VPRM and DDD groups. The mean follow-up period was 2.5 ± 0.9 years. Ventricular pacing reduction modalities showed uniform reduction in VP in comparison to DDD groups among all individual studies. The incidence of PerAF was similar between both groups {8 vs. 10%, OR 0.84 [95% confidence interval (CI) 0.57; 1.24], P = 0.38}. Ventricular pacing reduction modalities showed no significant differences in comparison to DDD for all-cause hospitalization or all-cause mortality [9 vs. 11%, OR 0.82 (95% CI 0.65; 1.03), P= 0.09; 6 vs. 6%, OR 0.97 (95% CI 0.74; 1.28), P = 0.84, respectively]. Novel VPRM measures effectively reduce VP in comparison to standard DDD. When actively programmed, VPRM did not improve clinical outcomes and were not superior to standard DDD programming in reducing incidence of PerAF, all-cause hospitalization, or all-cause mortality.

Cardiac resynchronization therapy by multipoint pacing improves response of left ventricular mechanics and fluid dynamics: a three-dimensional and particle image velocimetry echo study.

PubMed

Siciliano, Mariachiara; Migliore, Federico; Badano, Luigi; Bertaglia, Emanuele; Pedrizzetti, Gianni; Cavedon, Stefano; Zorzi, Alessandro; Corrado, Domenico; Iliceto, Sabino; Muraru, Denisa

2017-11-01

To characterize the effect of multipoint pacing (MPP) compared to biventricular pacing (BiV) on left ventricle (LV) mechanics and intraventricular fluid dynamics by three-dimensional echocardiography (3DE) and echocardiographic particle imaging velocimetry (Echo-PIV). In 11 consecutive patients [8 men; median age 65 years (57-75)] receiving cardiac resynchronization therapy (CRT) with a quadripolar LV lead (Quartet,St.Jude Medical,Inc.), 3DE and Echo-PIV data were collected for each pacing configuration (CRT-OFF, BiV, and MPP) at follow-up after 6 months. 3DE data included LV volumes, LV ejection fraction (LVEF), strain, and systolic dyssynchrony index (SDI). Echo-PIV was used to evaluate the directional distribution of global blood flow momentum, ranging from zero, when flow force is predominantly along the base-apex direction, up to 90° when it becomes transversal. MPP resulted in significant reduction in end-diastolic and end-systolic volumes compared with both CRT-OFF (P = 0.02; P = 0.008, respectively) and BiV (P = 0.04; P = 0.03, respectively). LVEF and cardiac output were significant superior in MPP compared with CRT-OFF, but similar between MPP and BiV. Statistical significant differences when comparing global longitudinal and circumferential strain and SDI with MPP vs. CRT-OFF were observed (P = 0.008; P = 0.008; P = 0.01, respectively). There was also a trend towards improvement in strain between BiV and MPP that did not reach statistical significance. MPP reflected into a significant reduction of the deviation of global blood flow momentum compared with both CRT-OFF and BiV (P = 0.002) indicating a systematic increase of longitudinal alignment from the base-apex orientation of the haemodynamic forces. These preliminary results suggest that MPP resulted in significant improvement of LV mechanics and fluid dynamics compared with BiV. However, larger studies are needed to confirm this hypothesis. © Crown copyright 2016.

Fatal outcome arising from use of a sutureless "corkscrew" epicardial pacing electrode inserted into apex of left ventricle.

PubMed Central

Vecht, R J; Fontaine, C J; Bradfield, J W

1976-01-01

A 59-year-old man is described in whom the insertion of an epicardial sutureless "corkscrew" electrode resulted in fatal ventricular perforation. Fatal myocardial perforation can occur with this electrode and the apex of the left ventricle should never be used as the site of insertion. Necropsy also showed that the transvenous right ventricular electrode, inserted one year previously, had penetrated a tricuspid leaflet. This could have accounted for the ensuing pacing failure. Images PMID:1008980

The Effect of Right Ventricular Apical and Nonapical Pacing on the Short- and Long-Term Changes in Left Ventricular Ejection Fraction: A Systematic Review and Meta-Analysis of Randomized-Controlled Trials.

PubMed

Hussain, Mohammad Akhtar; Furuya-Kanamori, Luis; Kaye, Gerald; Clark, Justin; Doi, Suhail A R

2015-09-01

The right ventricular apex (RVA) is the traditional lead site for chronic pacing but in some patients may cause impaired left ventricular (LV) systolic function over time. Comparisons with right ventricular nonapical (RVNA) pacing sites have generated inconsistent results and recent meta-analyses have demonstrated unclear benefit due to heterogeneity across studies. A systematic search for randomized controlled trials that compared LV ejection fraction (LVEF) outcomes between RVNA and RVA pacing was performed up to October 2014. Twenty-four studies (n = 1,628 patients) met the inclusion criteria. To avoid between study heterogeneity two homogenous groups were created; group 1 where studies reported a difference (in favor of RVNA pacing) and group 2 where studies reported no difference between pacing sites. For group 1, weighted mean difference between RVNA and RVA pacing in terms of LVEF at follow-up was 5.40% (95% confidence interval [CI]: 3.94-6.87), related in part to group one's RVA arm demonstrating a significant reduction (mean loss -3.31%; 95% CI: -6.19 to -0.43) in LVEF between study baseline and end of follow-up. Neither of these finding were seen in group 2. Weighted regression modeling demonstrated that inclusion of poor baseline LVEF (<40%) in combination with greater than 12 months follow-up was three times more common in group 1 compared to group 2 (weighted relative risk 2.82; 95% CI: 1.03-7.72; P = 0.043). In patients requiring chronic right ventricular pacing where there is inclusion of impaired baseline LVEF (<40%), RVA pacing is associated with deterioration in LV function relative to RVNA pacing. © 2015 Wiley Periodicals, Inc.

Pulmonary vein isolation using a pace-capture-guided versus an adenosine-guided approach: effect on dormant conduction and long-term freedom from recurrent atrial fibrillation--a prospective study.

PubMed

Andrade, Jason G; Pollak, Scott J; Monir, George; Khairy, Paul; Dubuc, Marc; Roy, Denis; Talajic, Mario; Deyell, Marc; Rivard, Léna; Thibault, Bernard; Guerra, Peter G; Nattel, Stanley; Macle, Laurent

2013-12-01

Atrial fibrillation recurrence after pulmonary vein (PV) isolation is associated with PV to left atrium reconduction. We prospectively studied the use of 2 procedural techniques designed to facilitate identification of residual gaps within the index ablation line. After wide circumferential PV isolation, 40 patients received additional ablation targeted at locations of left atrial capture during high-output pacing (pace-capture group), while 40 patients underwent adenosine testing with targeted ablation at sites of dormant conduction (adenosine group). Patients were followed up at 3, 6, and 12 months. After PV isolation, high-output pace-capture was documented in 39 PVs (25%; 50% of patients) in the pace-capture group. Dormant conduction was unmasked in 34 PVs (22%; 53% of patients) in the adenosine group. A subset of 25 patients in the pace-capture group underwent adenosine testing without targeted ablation of dormant conduction. In these patients, only 10 out of 86 PVs (11.6%; 24% of patients) demonstrated dormant conduction after the elimination of local pace-capture. At a follow-up of 329±124 days, the single procedure off antiarrhythmic drug freedom from recurrent atrial fibrillation was 67.5% in the adenosine group and 65.0% in the pace-capture group (P=0.814). Procedure duration and fluoroscopy time were significantly longer in the pace-capture group (P=0.002 and P<0.001), whereas radiofrequency ablation time was comparable (P=0.192). The use of high-output pacing post-PV isolation results in a significant reduction in the incidence of dormant conduction with a comparable long-term freedom from recurrent atrial fibrillation (versus adenosine-guided ablation). The use of these approaches requires evaluation in a long-term prospective randomized study. [corrected].

Effect of chronic right ventricular apical pacing on left ventricular function.

PubMed

O'Keefe, James H; Abuissa, Hussam; Jones, Philip G; Thompson, Randall C; Bateman, Timothy M; McGhie, A Iain; Ramza, Brian M; Steinhaus, David M

2005-03-15

The determinants of change in left ventricular (LV) ejection fraction (EF) over time in patients with impaired LV function at baseline have not been clearly established. Using a nuclear database to assess changes in LV function over time, we included patients with a baseline LVEF of 25% to 40% on a gated single-photon emission computed tomographic study at rest and only if second-gated photon emission computed tomography performed approximately 18 months after the initial study showed an improvement in LVEF at rest of > or =10 points or a decrease in LVEF at rest of > or =7 points. In all, 148 patients qualified for the EF increase group and 59 patients for the EF decrease group. LVEF on average increased from 33 +/- 4% to 51 +/- 8% in the EF increase group and decreased from 35 +/- 4% to 25 +/- 5% in the EF decrease group. The strongest multivariable predictor of improvement of LVEF was beta-blocker therapy (odds ratio 3.9, p = 0.002). The strongest independent predictor of LVEF decrease was the presence of a permanent right ventricular apical pacemaker (odds ratio 6.6, p = 0.002). Thus, this study identified beta-blocker therapy as the major independent predictor for improvement in LVEF of > or =10 points, whereas a permanent pacemaker (right ventricular apical pacing) was the strongest predictor of a LVEF decrease of > or =7 points.

Understanding pacing postconditioning-mediated cardiac protection: a role of oxidative stress and a synergistic effect of adenosine.

PubMed

Babiker, Fawzi A; Al-Jarallah, Aishah; Joseph, Shaji

2017-05-01

We and others have demonstrated a protective role for pacing postconditioning (PPC) against ischemia/reperfusion (I/R) injury in the heart; however, the underlying mechanisms behind these protective effects are not completely understood. In this study, we wanted to further characterize PPC-mediated cardiac protection, specifically identify optimal pacing sites; examine the role of oxidative stress; and test the existence of a potential synergistic effect between PPC and adenosine. Isolated rat hearts were subjected to coronary occlusion followed by reperfusion. PPC involved three, 30 s, episodes of alternating left ventricular (LV) and right atrial (RA) pacing. Multiple pacing protocols with different pacing electrode locations were used. To test the involvement of oxidative stress, target-specific agonists or antagonists were infused at the beginning of reperfusion. Hemodynamic data were digitally recorded, and cardiac enzymes, oxidant, and antioxidant status were chemically measured. Pacing at the LV or RV but not at the heart apex or base significantly (P < 0.001) protected against ischemia-reperfusion injury. PPC-mediated protection was completely abrogated in the presence of reactive oxygen species (ROS) scavenger, ebselen; peroxynitrite (ONOO - ) scavenger, uric acid; and nitric oxide synthase inhibitor, L-NAME. Nitric oxide (NO) donor, snap, however significantly (P < 0.05) protected the heart against I/R injury in the absence of PPC. The protective effects of PPC were significantly improved by adenosine. PPC-stimulated protection can be achieved by alternating LV and RA pacing applied at the beginning of reperfusion. NO, ROS, and the product of their interaction ONOO - play a significant role in PPC-induced cardiac protection. Finally, the protective effects of PPC can be synergized with adenosine.

The association between left ventricular twisting motion and mechanical dyssynchrony: a three-dimensional speckle tracking study.

PubMed

Fujiwara, Shohei; Komamura, Kazuo; Nakabo, Ayumi; Masaki, Mitsuru; Fukui, Miho; Sugahara, Masataka; Itohara, Kanako; Soyama, Yuko; Goda, Akiko; Hirotani, Shinichi; Mano, Toshiaki; Masuyama, Tohru

2016-02-01

Left ventricular (LV) dyssynchrony is a causal factor in LV dysfunction and thought to be associated with LV twisting motion. We tested whether three-dimensional speckle tracking (3DT) can be used to evaluate the relationship between LV twisting motion and dyssynchrony. We examined 25 patients with sick sinus syndrome who had received dual chamber pacemakers. The acute effects of ventricular pacing on LV wall motion after the switch from atrial to ventricular pacing were assessed. LV twisting motion and dyssynchrony during each pacing mode were measured using 3DT. LV dyssynchrony was calculated from the time to the minimum peak systolic area strain of 16 LV imaging segments. Ventricular pacing increased LV dyssynchrony and decreased twist and torsion. A significant correlation was observed between changes in LV dyssynchrony and changes in torsion (r = -0.65, p < 0.01). Evaluation of LV twisting motion can potentially be used for diagnosing LV dyssynchrony.

Amiodarone. Haemodynamic profile during intravenous administration and effect on pacing-induced ischaemia in man.

PubMed

Remme, W J; van Hoogenhuyze, D C; Kruyssen, D A; Krauss, X H; Storm, C J

1985-03-01

The haemodynamic changes during intravenous amiodarone administration in laboratory animals and human studies are reviewed and compared with the results from our investigations. While the results of previous human studies have been rather variable, our investigations suggest that the cardiovascular changes following intravenous amiodarone include an early and usually short reduction of systemic and coronary vascular resistance, which may be partially due to the vasodilating properties of the solvent, polysorbate 80. As a result, a decrease in afterload and cardiac work and increases in cardiac output and coronary blood flow occur. Contrary to the observations in the animal experiments, heart rate increases in man, presumably as a result of the relatively greater fall in afterload which occurs. However, in spite of this increase in heart rate, contractility is reduced at the end of amiodarone administration and remains depressed after the infusion, resulting in a significant increase in left ventricular filling pressure. Neither myocardial oxygen demand nor consumption change during amiodarone administration. Although the intrinsic negative inotropic effects of amiodarone warrant a cautious approach in patients with left ventricular dysfunction, worsening of heart failure or the occurrence of myocardial ischaemia has been reported in only very few cases so far. In contrast, the drug was demonstrated to protect against pacing-induced myocardial ischaemia, in patients with both normal and depressed left ventricular function. These anti-ischaemic properties of amiodarone were investigated in a second study using a double pacing stress test protocol. Overall myocardial oxygen consumption did not change during pacing after amiodarone, but it clearly reduced (regional) myocardial ischaemia, as demonstrated by a reduction of ST-segment changes and anginal pain, and in particular by the absence of myocardial lactate production during pacing after amiodarone. These anti-ischaemic properties are mainly based on a reduction of myocardial oxygen demand, rather than on an improvement in coronary flow. It is concluded then, that amiodarone has significant haemodynamic effects as manifested by an early reduction in vascular resistance and a late negative inotropic effect. Although vasodilatation of short duration caused by its solvent, polysorbate 80, also occurs, the overall cardiovascular changes are caused by the direct, intrinsic haemodynamic effects of amiodarone alone. The important anti-ischaemic properties of amiodarone appear to result primarily from these cardiovascular actions and the inherent reduction in myocardial oxygen demand.

Transvenous versus open chest lead placement for resynchronization therapy in patients with heart failure: comparison of ventricular electromechanical synchronicity.

PubMed

Zhang, Hai-Bo; Meng, Xu; Han, Jie; Li, Yan; Zhang, Ye; Jiang, Teng-Yong; Zhao, Ying-Xin; Zhou, Yu-Jie

2017-04-01

Transvenous lead placement is the standard approach for left ventricular (LV) pacing in cardiac resynchronization therapy (CRT), while the open chest access epicardial lead placement is currently the most frequently used second choice. Our study aimed to compare the ventricular electromechanical synchronicity in patients with heart failure after CRT with these two different LV pacing techniques. We enrolled 33 consecutive patients with refractory heart failure secondly to dilated cardiomyopathy who were eligible for CRT in this study. Nineteen patients received transvenous (TV group) while 14 received open chest (OP group) LV lead pacing. Intra- and inter-ventricular electromechanical synchronicity was assessed by tissue Doppler imaging (TDI) before and one year after CRT procedure. Before CRT procedure, the mean QRS-duration, maximum time difference to systolic peak velocity among 12 left ventricle segments (LV Ts-12), standard deviation of time difference to systolic peak velocity of 12 left ventricle segments (LV Ts-SD), and inter-ventricular mechanical delay (IVMD) in OP and TV group were 166 ± 17 ms and 170 ± 21 ms, 391 ± 42 ms and 397 ± 36 ms, 144 ± 30 ms and 148 ± 22 ms, 58 ± 25 ms and 60 ± 36 ms, respectively (all P > 0.05). At one year after the CRT, the mean QRS-duration, LV Ts-12, LV Ts-SD, and IVMD in TV and OP group were 128 ± 14 ms and 141 ± 22 ms ( P = 0.031), 136 ± 37 ms and 294 ± 119 ms ( P = 0.023), 50 ± 22 ms and 96 ± 34 ms ( P = 0.015), 27 ± 11 ms and 27 ± 26 ms ( P = 0.86), respectively. The LV lead implantation procedure time was 53.4 ± 16.3 min for OP group and 136 ± 35.1 min for TV group ( P = 0.016). The mean LV pacing threshold increased significantly from 1.7 ± 0.6 V/0.5 ms to 2.3 ± 1.6 V/0.5 ms ( P < 0.05) in TV group while it remained stable in the OP group. Compared to conventional endovascular approach, open chest access of LV pacing for CRT leads to better improvement of the intraventricular synchronization.

Multipoint Pacing versus conventional ICD in Patients with a Narrow QRS complex (MPP Narrow QRS trial): study protocol for a pilot randomized controlled trial.

PubMed

Gasparini, Maurizio; Galimberti, Paola; Bragato, Renato; Ghio, Stefano; Raineri, Claudia; Landolina, Maurizio; Chieffo, Enrico; Lunati, Maurizio; Mulargia, Ederina; Proclemer, Alessandro; Facchin, Domenico; Rordorf, Roberto; Vicentini, Alessandro; Marcantoni, Lina; Zanon, Francesco; Klersy, Catherine

2016-12-03

Despite an intensive search for predictors of the response to cardiac resynchronization therapy (CRT), the QRS duration remains the simplest and most robust predictor of a positive response. QRS duration of ≥ 130 ms is considered to be a prerequisite for CRT; however, some studies have shown that CRT may also be effective in heart failure (HF) patients with a narrow QRS (<130 ms). Since CRT can now be performed by pacing the left ventricle from multiple vectors via a single quadripolar lead, it is possible that multipoint pacing (MPP) might be effective in HF patients with a narrow QRS. This article reports the design of the MPP Narrow QRS trial, a prospective, randomized, multicenter, controlled feasibility study to investigate the efficacy of MPP using two LV pacing vectors in patients with a narrow QRS complex (100-130 ms). Fifty patients with a standard ICD indication will be enrolled and randomized (1:1) to either an MPP group or a Standard ICD group. All patients will undergo a low-dose dobutamine stress echo test and only those with contractile reserve will be included in the study and randomized. The primary endpoint will be the percentage of patients in each group that have reverse remodeling at 12 months, defined as a reduction in left ventricular end-systolic volume (LVESV) of >15% from the baseline. This feasibility study will determine whether MPP improves reverse remodeling, as compared with standard ICD, in HF patients who have a narrow QRS complex (100-130 ms). ClinicalTrials.gov, NCT02402816 . Registered on 25 March 2015.

Angiotensin-converting enzyme and matrix metalloproteinase inhibition with developing heart failure: comparative effects on left ventricular function and geometry

NASA Technical Reports Server (NTRS)

McElmurray, J. H. 3rd; Mukherjee, R.; New, R. B.; Sampson, A. C.; King, M. K.; Hendrick, J. W.; Goldberg, A.; Peterson, T. J.; Hallak, H.; Zile, M. R.;

Nonsurgical reduction of the interventricular septum in patients with hypertrophic cardiomyopathy.

PubMed

Shamim, Waqar; Yousufuddin, Mohammed; Wang, Duolao; Henein, Michael; Seggewiss, Hubert; Flather, Marcus; Coats, Andrew J S; Sigwart, Ulrich

2002-10-24

In patients with hypertrophic cardiomyopathy and obstruction of the left ventricular outflow tract, nonsurgical reduction of the septum is a treatment option when medical therapy has failed. We investigated the long-term effects of nonsurgical reduction of the septum on functional capacity and electrocardiographic and echocardiographic characteristics. Sixty-four consecutive patients with hypertrophic cardiomyopathy and a mean (+/-SD) age of 48.5+/-17.2 years underwent nonsurgical reduction of the septum by injection of ethanol into the septal perforator branch of the left anterior descending coronary artery. These patients were assessed by exercise testing, electrocardiography, and resting and dobutamine (stress-induced) echocardiography after a mean period of 3.0+/-1.3 years. At follow-up, patients had significant improvements in New York Heart Association class, peak oxygen consumption (from 18.4+/-5.8 to 30.0+/-4.4 ml per kilogram of body weight per minute, P<0.001), and left ventricular outflow tract gradients (resting gradient, from 64+/-36 to 16+/-15 mm Hg; P<0.001; stress-induced gradient, from 132+/-34 to 45+/-19 mm Hg; P<0.001). Procedure-related complications included right bundle-branch block in all patients, complete heart block in 31 patients (48 percent), and significant increases in QRS and corrected QT intervals. Seventeen patients (27 percent) required permanent pacing. R-wave amplitude was significantly decreased (from 32+/-8 to 17+/-7 mV, P<0.001). The dimensions of the left ventricular cavity increased, and the interventricular septal thickness was reduced. Nonsurgical septal reduction leads to sustained improvements in both subjective and objective measures of exercise capacity in association with a persistent reduction in resting and stress-induced left ventricular outflow tract gradients. It is also associated with a high incidence of procedure-related complete heart block, however, often requiring permanent pacing. Copyright 2002 Massachusetts Medical Society

ALternate Site Cardiac ResYNChronization (ALSYNC): a prospective and multicentre study of left ventricular endocardial pacing for cardiac resynchronization therapy.

PubMed

Morgan, John M; Biffi, Mauro; Gellér, László; Leclercq, Christophe; Ruffa, Franco; Tung, Stanley; Defaye, Pascal; Yang, Zhongping; Gerritse, Bart; van Ginneken, Mireille; Yee, Raymond; Jais, Pierre

2016-07-14

The ALternate Site Cardiac ResYNChronization (ALSYNC) study evaluated the feasibility and safety of left ventricular endocardial pacing (LVEP) using a market-released pacing lead implanted via a single pectoral access by a novel atrial transseptal lead delivery system. ALSYNC was a prospective clinical investigation with a minimum of 12-month follow-up in 18 centres of cardiac resynchronization therapy (CRT)-indicated patients, who had failed or were unsuitable for conventional CRT. The ALSYNC system comprises the investigational lead delivery system and LVEP lead. Patients required warfarin therapy post-implant. The primary study objective was safety at 6-month follow-up, which was defined as freedom from complications related to the lead delivery system, implant procedure, or the lead ≥70%. The ALSYNC study enrolled 138 patients. The LVEP lead implant success rate was 89.4%. Freedom from complications meeting the definition of primary endpoint was 82.2% at 6 months (95% CI 75.6-88.8%). In the study, 14 transient ischaemic attacks (9 patients, 6.8%), 5 non-disabling strokes (5 patients, 3.8%), and 23 deaths (17.4%) were observed. No death was from a primary endpoint complication. At 6 months, the New York Heart Association class improved in 59% of patients, and 55% had LV end-systolic volume reduction of 15% or greater. Those patients enrolled after CRT non-response showed similar improvement with LVEP. The ALSYNC study demonstrates clinical feasibility, and provides an early indication of possible benefit and risk of LVEP. NCT01277783. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Recombinant glucagon-like peptide-1 increases myocardial glucose uptake and improves left ventricular performance in conscious dogs with pacing-induced dilated cardiomyopathy.

PubMed

Nikolaidis, Lazaros A; Elahi, Dariush; Hentosz, Teresa; Doverspike, Aaron; Huerbin, Rhonda; Zourelias, Lee; Stolarski, Carol; Shen, You-tang; Shannon, Richard P

2004-08-24

The failing heart demonstrates a preference for glucose as its metabolic substrate. Whether enhancing myocardial glucose uptake favorably influences left ventricular (LV) contractile performance in heart failure remains uncertain. Glucagon-like peptide-1 (GLP-1) is a naturally occurring incretin with potent insulinotropic effects the action of which is attenuated when glucose levels fall below 4 mmol. We examined the impact of recombinant GLP-1 (rGLP-1) on LV and systemic hemodynamics and myocardial substrate uptake in conscious dogs with advanced dilated cardiomyopathy (DCM) as a mechanism for overcoming myocardial insulin resistance and enhancing myocardial glucose uptake. Thirty-five dogs were instrumented and studied in the fully conscious state. Advanced DCM was induced by 28 days of rapid pacing. Sixteen dogs with advanced DCM received a 48-hour infusion of rGLP-1 (1.5 pmol x kg(-1) x min(-1)). Eight dogs with DCM served as controls and received 48 hours of a saline infusion (3 mL/d). Infusion of rGLP-1 was associated with significant (P<0.02) increases in LV dP/dt (98%), stroke volume (102%), and cardiac output (57%) and significant decreases in LV end-diastolic pressure, heart rate, and systemic vascular resistance. rGLP-1 increased myocardial insulin sensitivity and myocardial glucose uptake. There were no significant changes in the saline control group. rGLP-1 dramatically improved LV and systemic hemodynamics in conscious dogs with advanced DCM induced by rapid pacing. rGLP-1 has insulinomimetic and glucagonostatic properties, with resultant increases in myocardial glucose uptake. rGLP-1 may be a useful metabolic adjuvant in decompensated heart failure.

Validation of Electromechanical Wave Imaging in a canine model during pacing and sinus rhythm

PubMed Central

Grondin, Julien; Costet, Alexandre; Bunting, Ethan; Gambhir, Alok; Garan, Hasan; Wan, Elaine; Konofagou, Elisa E.

2016-01-01

Background Accurate determination of regional areas of arrhythmic triggers is of key interest to diagnose arrhythmias and optimize their treatment. Electromechanical wave imaging (EWI) is an ultrasound technique that can image the transient deformation in the myocardium following electrical activation and therefore has the potential to detect and characterize location of triggers of arrhythmias. Objectives The objectives of this study are to investigate the relationship between electromechanical and electrical activation of the left-ventricular (LV) endocardial surface during epicardial and endocardial pacing as well as during sinus rhythm and also to investigate the distribution of electromechanical delays. Methods In this study, six canines were investigated. Two external electrodes were sutured onto the epicardial surface of the left ventricle (LV). A 64-electrode basket catheter was inserted through the apex of the LV. Ultrasound channel data were acquired at 2000 frames/s during epicardial and endocardial pacing as well as during sinus rhythm. Electromechanical and electrical activation maps were synchronously obtained from the ultrasound data and the basket catheter respectively. Results The mean correlation coefficient between electromechanical and electrical activation was R=0.81 for epicardial anterior pacing, R=0.79 for epicardial lateral pacing, R=0.69 for endocardial pacing and R=0.56 for sinus rhythm. Conclusions The electromechanical activation sequence determined by EWI follows the electrical activation sequence and more specifically in the case of pacing. This finding is of key interest in the role that EWI can play in the detection of the anatomical source of arrhythmias and the planning of pacing therapies such as cardiovascular resynchronization therapy. PMID:27498277

Right heart failure due to loss of right ventricular capture in a patient with atrioventricular junction ablation and biventricular pacing.

PubMed

Raffa, Santi; Fantoni, Cecilia; Restauri, Luigia; Auricchio, Angelo

2005-10-01

We describe the case of a patient with atrioventricular (AV) junction ablation and chronic biventricular pacing in which intermittent dysfunction of the right ventricular (RV) lead resulted in left ventricular (LV) stimulation alone and onset of severe right heart failure. Restoration of biventricular pacing by increasing device output and then performing lead revision resolved the issue. This case provides evidence that LV pacing alone in patients with AV junction ablation may lead to severe right heart failure, most likely as a result of iatrogenic mechanical dyssynchrony within the RV. Thus, probably this pacing mode should be avoided in pacemaker-dependent patients with heart failure.

Time to Act: An Agenda for Advancing Adolescent Literacy for College and Career Success. Final Report from Carnegie Corporation of New York's Council on Advancing Adolescent Literacy

ERIC Educational Resources Information Center

Carnegie Corporation of New York, 2011

2011-01-01

Our nation's educational system has scored many extraordinary successes in raising the level of reading and writing skills in younger children. Yet the pace of literacy improvement in our schools has not kept up with the accelerating demands of the global knowledge economy. In state after state, the testing data mandated by No Child Left Behind…

Right bundle branch block pattern during right ventricular permanent pacing: Is it safe or not?

PubMed Central

Erdogan, Okan; Aksu, Feyza

2007-01-01

The present case report describes a patient with dual chamber pacemaker whose surface ECG demonstrated paced right bundle branch block pattern suggesting a malpositioned ventricular lead in the left ventricle. However, diagnostic work-up revealed that the lead was appropriately located in the right ventricular apex. Diagnostic maneuvers and clues for differentiating safe right bundle branch block pattern during permanent pacing are thoroughly revisited and discussed within the article. PMID:17684578

Left ventricular epicardial activation increases transmural dispersion of repolarization in healthy, long QT, and dilated cardiomyopathy dogs.

PubMed

Bai, Rong; Lü, Jiagao; Pu, Jun; Liu, Nian; Zhou, Qiang; Ruan, Yanfei; Niu, Huiyan; Zhang, Cuntai; Wang, Lin; Kam, Ruth

2005-10-01

Benefits of cardiac resynchronization therapy (CRT) are well established. However, less is understood concerning its effects on myocardial repolarization and the potential proarrhythmic risk. Healthy dogs (n = 8) were compared to a long QT interval (LQT) model (n = 8, induced by cesium chloride, CsCl) and a dilated cardiomyopathy with congestive heart failure (DCM-CHF, induced by rapid ventricular pacing, n = 5). Monophasic action potential (MAP) recordings were obtained from the subendocardium, midmyocardium, subepicardium, and the transmural dispersion of repolarization (TDR) was calculated. The QT interval and the interval from the peak to the end of the T wave (T(p-e)) were measured. All these characteristics were compared during left ventricular epicardial (LV-Epi), right ventricular endocardial (RV-Endo), and biventricular (Bi-V) pacing. In healthy dogs, TDR prolonged to 37.54 ms for Bi-V pacing and to 47.16 ms for LV-Epi pacing as compared to 26.75 ms for RV-Endo pacing (P < 0.001), which was parallel to an augmentation in T(p-e) interval (Bi-V pacing, 64.29 ms; LV-Epi pacing, 57.89 ms; RV-Endo pacing, 50.29 ms; P < 0.01). During CsCl exposure, Bi-V and LV-Epi pacing prolonged MAPD, TDR, and T(p-e) interval as compared to RV-Endo pacing. The midmyocardial MAPD (276.30 ms vs 257.35 ms, P < 0.0001) and TDR (33.80 ms vs 27.58 ms, P=0.002) were significantly longer in DCM-CHF dogs than those in healthy dogs. LV-Epi and Bi-V pacing further prolonged the MAPD and TDR in this model. LV-Epi and Bi-V pacing result in prolongation of ventricular repolarization time, and increase of TDR accounted for a parallel augmentation of the T(p-e) interval, which provides evidence that T(p-e) interval accurately represents TDR. These effects are magnified in the LQT and DCM-CHF canine models in addition to their intrinsic transmural heterogeneity in the intact heart. This mechanism may contribute to the development of malignant ventricular arrhythmias, such as torsades de pointes (TdP) in congestive heart failure (CHF) patients treated with CRT.

Is the epicardial left ventricular lead implantation an alternative approach to percutaneous attempt in patients with Steinert disease? A case report

PubMed Central

PAPA, ANDREA ANTONIO; RAGO, ANNA; PETILLO, ROBERTA; D’AMBROSIO, PAOLA; SCUTIFERO, MARIANNA; FEO, MARISA DE; MAIELLO, CIRO; PALLADINO, ALBERTO

2017-01-01

Steinert’s disease or Myotonic Dystrophy type 1 (DM1) is an autosomal dominant multisystemic disorder characterized by myotonia, muscle and facial weakness, cataracts, cognitive, endocrine and gastrointestinal involvement, and cardiac conduction abnormalities. Although mild myocardial dysfunction may be detected in this syndrome with age, overt myocardial dysfunction with heart failure is not frequent. Cardiac resynchronization therapy is an effective treatment to improve morbidity and reduce mortality in patients with DM1 showing intra-ventricular conduction delay and/or congestive heart failure. We report the case of a patient with Steinert disease showing an early onset ventricular dysfunction due to chronic right ventricular apical pacing, in which an epicardial left ventricular lead implantation was performed following the failure of the percutaneous attempt. As no relief in symptoms of heart failure, nor an improvement of left ventricular ejection fraction and reverse remodelling was observed six months later, the patient was addressed to the heart transplantation.

Biventricular pacing preserves left ventricular performance in patients with high-grade atrio-ventricular block: a randomized comparison with DDD(R) pacing in 50 consecutive patients.

PubMed

Albertsen, Andi E; Nielsen, Jens C; Poulsen, Steen H; Mortensen, Peter T; Pedersen, Anders K; Hansen, Peter S; Jensen, Henrik K; Egeblad, Henrik

2008-03-01

We aimed to investigate whether biventricular (BiV) pacing minimizes left ventricular (LV) dyssynchrony and preserves LV ejection fraction (LVEF) as compared with standard dual-chamber DDD(R) pacing in consecutive patients with high-grade atrio-ventricular (AV) block. Fifty patients were randomized to DDD(R) pacing or BiV pacing. LVEF was measured using three-dimensional echocardiography. Tissue-Doppler imaging was used to quantify LV dyssynchrony in terms of number of segments with delayed longitudinal contraction (DLC). LVEF was not different between groups after 12 months (P = 0.18). In the DDD(R) group LVEF decreased significantly from 59.7(57.4-61.4)% at baseline to 57.2(52.1-60.6)% at 12 months of follow-up (P = 0.03), whereas LVEF remained unchanged in the BiV group [58.9(47.1-61.7)% at baseline vs. 60.1(55.2-63.3)% after 12 months (P = 0.15)]. Dyssynchrony was more prominent in the DDD(R) group than in the BiV group at baseline (2.2 +/- 2.2 vs. 1.4 +/- 1.3 segments with DLC per patient, P = 0.10); and at 12 month follow-up (1.8 +/- 1.9 vs. 0.8 +/- 0.9 segments with DLC per patient, P = 0.02). NT-proBNP was unchanged in the DDD(R) group during follow-up (122 +/- 178 pmol/L vs. 91 +/- 166 pmol/L, NS) but decreased significantly in the BiV-group (from 198 +/- 505 pmol/L to 86 +/- 95 pmol/L after 12 months, P = 0.02). BiV pacing minimizes LV dyssynchrony, preserves LV function, and reduces NT-proBNP in contrast to DDD(R) pacing in patients with high-grade AV block.

DDD pacemaker for severe heart failure-alternate to CRT.

PubMed

Krishnamani, N C

Patients with severe systolic Heart Failure continue to have poor quality of life and increased mortality in spite of optimal medical management. Cardiac Resynchronization Therapy [CRT] is promising modality in patients with systolic heart failure and electrocardiographic [ECG] evidence of left bundle branch block [LBBB]. Cost issues continue to elude many deserving cases of this therapy in our society. Relatively cost effective Dual chamber pacing [DDD] with right atrial and isolated left ventricular pacing [RA-LV] can be a good alternative. Copyright © 2016 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

The implantable cardioverter defibrillator: technology, indications, and impact on cardiovascular survival.

PubMed

Bhatia, Atul; Cooley, Ryan; Berger, Marcie; Blanck, Zalmen; Dhala, Anwer; Sra, Jasbir; Axtell-Mcbride, Kathleen; Vandervort, Cheryl; Akhtar, Masood

2004-06-01

Since the introduction of the implantable cardioverter defibrillator (ICD) for the management of patients with high risk of arrhythmic SCD, there has been increasing use of this device. Its basic promise to effectively terminate ventricular tachycardia (VT)-ventricular fibrillation (VF) has been repeatedly met. In several randomized trials, the ICD has been shown to be superior to conventional anti-arrhythmic therapy, both in patients with documented VT-VF (secondary prevention) and those with high risk such as left ventricular ejection fraction and no prior sustained VT-VF (primary prevention). In both groups, the ICD showed overall and cardiac mortality reduction. The device now can more accurately detect VT-VF and differentiate these from other arrhythmias through a series of algorithms and direct-chamber sensing. Therapy options include painless antitachycardia pacing, low-energy cardioversion, and high-energy defibrillation. The technique implant is now simple as a pacemaker with one lead attached to an active (hot) can functioning as the other electrode. Among other improvements is its weight, volume, multiprogrammability, and storage of information,dual-chamber pacing and sensing, dual-chamber defibrillation, and addition of biventricular pacing for cardiac synchronization. It is anticipated that further improvement in ICD technology will take place and the list of indications will grow.

Cardiac resynchronization therapy and atrial overdrive pacing for the treatment of central sleep apnoea

PubMed Central

Lüthje, Lars; Renner, Bernd; Kessels, Roger; Vollmann, Dirk; Raupach, Tobias; Gerritse, Bart; Tasci, Selcuk; Schwab, Jörg O.; Zabel, Markus; Zenker, Dieter; Schott, Peter; Hasenfuss, Gerd; Unterberg-Buchwald, Christina; Andreas, Stefan

2009-01-01

Aims The combined therapeutic impact of atrial overdrive pacing (AOP) and cardiac resynchronization therapy (CRT) on central sleep apnoea (CSA) in chronic heart failure (CHF) so far has not been investigated. We aimed to evaluate the effect of CRT alone and CRT + AOP on CSA in CHF patients and to compare the influence of CRT on CHF between CSA positive and CSA negative patients. Methods and results Thirty patients with CRT indication underwent full night polysomnography, echocardiography, exercise testing, and neurohumoral evaluation before and 3 months after CRT implantation. In CSA positive patients (60%), two additional sleep studies were conducted after 3 months of CRT, with CRT alone or CRT + AOP, in random order. Cardiac resynchronization therapy resulted in significant improvements of NYHA class, left ventricular ejection fraction, N-terminal pro-brain natriuretic peptide, VO2max, and quality of life irrespective of the presence of CSA. Cardiac resynchronization therapy also reduced the central apnoea–hypopnoea index (AHI) (33.6 ± 14.3 vs. 23.8 ± 16.9 h−1; P < 0.01) and central apnoea index (17.3 ± 14.1 vs. 10.9 ± 13.9 h−1; P < 0.01) without altering sleep stages. Cardiac resynchronization therapy with atrial overdrive pacing resulted in a small but significant additional decrease of the central AHI (23.8 ± 16.9 vs. 21.5 ± 16.9 h−1; P < 0.01). Conclusion In this study, CRT significantly improved CSA without altering sleep stages. Cardiac resynchronization therapy with atrial overdrive pacing resulted in a significant but minor additional improvement of CSA. Positive effects of CRT were irrespective of the presence of CSA. PMID:19147446

Stimulus rate increases lateralisation in linguistic and non-linguistic tasks measured by functional transcranial Doppler sonography

PubMed Central

Payne, Heather; Gutierrez-Sigut, Eva; Subik, Joanna; Woll, Bencie; MacSweeney, Mairéad

2016-01-01

Studies to date that have used fTCD to examine language lateralisation have predominantly used word or sentence generation tasks. Here we sought to further assess the sensitivity of fTCD to language lateralisation by using a metalinguistic task which does not involve novel speech generation: rhyme judgement in response to written words. Line array judgement was included as a non-linguistic visuospatial task to examine the relative strength of left and right hemisphere lateralisation within the same individuals when output requirements of the tasks are matched. These externally paced tasks allowed us to manipulate the number of stimuli presented to participants and thus assess the influence of pace on the strength of lateralisation. In Experiment 1, 28 right-handed adults participated in rhyme and line array judgement tasks and showed reliable left and right lateralisation at the group level for each task, respectively. In Experiment 2 we increased the pace of the tasks, presenting more stimuli per trial. We measured laterality indices (LIs) from 18 participants who performed both linguistic and non-linguistic judgement tasks during the original ‘slow’ presentation rate (5 judgements per trial) and a fast presentation rate (10 judgements per trial). The increase in pace led to increased strength of lateralisation in both the rhyme and line conditions. Our results demonstrate for the first time that fTCD is sensitive to the left lateralised processes involved in metalinguistic judgements. Our data also suggest that changes in the strength of language lateralisation, as measured by fTCD, are not driven by articulatory demands alone. The current results suggest that at least one aspect of task difficulty, the pace of stimulus presentation, influences the strength of lateralisation during both linguistic and non-linguistic tasks. PMID:25908491

Clinical and echocardiographic response of apical vs nonapical right ventricular lead position in CRT: A meta-analysis.

PubMed

Sharma, Sharan Prakash; Dahal, Khagendra; Dominic, Paari; Sangha, Rajbir S

2018-04-01

Traditionally the right ventricular (RV) pacing lead is placed in the RV apex in cardiac resynchronization therapy (CRT). It is not clear whether nonapical placement of the RV lead is associated with a better response to CRT. We aimed to perform a meta-analysis of all randomized controlled trials (RCTs) that compared apical and nonapical RV lead placement in CRT. We searched PubMed, EMBASE, Cochrane, Scopus, and relevant references for studies and performed meta-analysis using random effects model. Our main outcome measures were all-cause mortality, composite of death and heart failure hospitalization, improvement in ejection fraction (EF), left ventricle end-diastolic volume (LVEDV), left ventricle end-systolic volume (LVESV), and adverse events. Seven RCTs with a total population of 1641 patients (1199 apical and 492 nonapical) were included in our meta-analysis. There was no difference in all-cause mortality (5% vs 4.3%, odds ratio (OR) = 0.86; 95% confidence interval (CI) 0.45-1.64; P  =   .65; I 2  = 11%) and a composite of death and heart failure hospitalization (14.2% vs 12.9%, OR   = 0.92; 95% CI: 0.61-1.38; P =  .68; I 2  = 0) between apical and nonapical groups. No difference in improvement in EF (Weighted mean difference (WMD)   = 0.37; 95% CI: -2.75-3.48; P =  .82; I 2  = 68%), change in LVEDV (WMD   = 3.67; 95% CI: -4.86-12.20; P  =   .40; I 2  = 89%) and LVESV (WMD   = -1.20; 95% CI: -4.32-1.91; P  =   .45; I 2  = 0) were noted between apical and nonapical groups. Proportion of patients achieving >15% improvement in EF was similar in both groups (OR   = 0.85; 95% CI: 0.62-1.16; P  =   .31; I 2  = 0). In patients with CRT, nonapical RV pacing is not associated with improved clinical and echocardiographic outcomes compared with RV apical pacing.

Optimal pacing for right ventricular and biventricular devices: minimizing, maximizing, and right ventricular/left ventricular site considerations.

PubMed

Gillis, Anne M

2014-10-01

The results from numerous clinical studies provide guidance for optimizing outcomes related to RV or biventricular pacing in the pacemaker and ICD populations. (1) Programming algorithms to minimize RV pacing is imperative in patients with dual-chamber pacemakers who have intrinsic AV conduction or intermittent AV conduction block. (2) Dual-chamber ICDs should be avoided in candidates without an indication for bradycardia pacing. (3) Alternate RV septal pacing sites may be considered at the time of pacemaker implantation. (4) Biventricular pacing may be beneficial in some patients with mild LV dysfunction. (5) LV lead placement at the site of latest LV activation is desirable. (6) Programming CRT systems to achieve biventricular/LV pacing >98.5% is important. (7) Protocols for AV and VV optimization in patients with CRT are not recommended after device implantation but may be considered for CRT nonresponders. (8) Novel algorithms to maximize the benefit of CRT are in evolution further.

Traumatic displacement of stomach - a case report.

PubMed

Janardhanan, Joshima; Tarvadi, Pratik Vijay; Manipady, Shahnavaz; Shetty, Mahabalesh; Somashekar, C

2014-01-01

These days we have fast paced traffic on our roads to help us keep up with our fast paced life. But every boon has a down side and our high velocity traffic is no exception. Here is a case report of a blunt abdominal injury following a road traffic accident. Externally the deceased had only a few grazed abrasions on the forehead and right forearm. But on internal examination of abdomen, it was noticed that the left hemi-diaphragm was torn and the stomach and intestines were found displaced into the left thoracic cavity. Copyright © 2013 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Anodal right ventricular capture during left ventricular stimulation in CRT-implantable cardioverter defibrillators.

PubMed

Thibault, Bernard; Roy, Denis; Guerra, Peter G; Macle, Laurent; Dubuc, Marc; Gagné, Pierre; Greiss, Isabelle; Novak, Paul; Furlani, Aldo; Talajic, Mario

2005-07-01

Cardiac resynchronization therapy (CRT) has been shown to improve symptoms of patients with moderate to severe heart failure. Optimal CRT involves biventricular or left ventricular (LV) stimulation alone, atrio-ventricular (AV) delay optimization, and possibly interventricular timing adjustment. Recently, anodal capture of the right ventricle (RV) has been described for patients with CRT-pacemakers. It is unknown whether the same phenomenon exists in CRT systems associated with defibrillators (CRT-ICD). The RV leads used in these systems are different from pacemaker leads: they have a larger diameter and shocking coils, which may affect the occurrence of anodal capture. We looked for anodal RV capture during LV stimulation in 11 consecutive patients who received a CRT-ICD system with RV leads with a true bipolar design. Fifteen patients who had RV leads with an integrated design were used as controls. Anodal RV and LV thresholds were determined at pulse width (pw) durations of 0.2, 0.5, and 1.0 ms. RV anodal capture during LV pacing was found in 11/11 patients at some output with true bipolar RV leads versus 0/15 patients with RV leads with an integrated bipolar design. Anodal RV capture threshold was more affected by changes in pw duration than LV capture threshold. In CRT-ICD systems, RV leads with a true bipolar design with the proximal ring also used as the anode for LV pacing are associated with a high incidence of anodal RV capture during LV pacing. This may affect the clinical response to alternative resynchronization methods using single LV stimulation or interventricular delay programming.

Right ventricular septal pacing: the success of stylet-driven active-fixation leads.

PubMed

Rosso, Raphael; Teh, Andrew W; Medi, Caroline; Hung, Thuy To; Balasubramaniam, Richard; Mond, Harry G

2010-01-01

The detrimental effects of right ventricular (RV) apical pacing on left ventricular function has driven interest in alternative pacing sites and in particular the mid RV septum and RV outflow tract (RVOT). RV septal lead positioning can be successfully achieved with a specifically shaped stylet and confirmed by the left anterior oblique (LAO) fluoroscopic projection. Such a projection is neither always used nor available during pacemaker implantation. The aim of this study was to evaluate how effective is the stylet-driven technique in septal lead placement guided only by posterior-anterior (PA) fluoroscopic view. One hundred consecutive patients with an indication for single- or dual-chamber pacing were enrolled. RV septal lead positioning was attempted in the PA projection only and confirmed by the LAO projection at the end of the procedure. The RV lead position was septal in 90% of the patients. This included mid RV in 56 and RVOT in 34 patients. There were no significant differences in the mean stimulation threshold, R-wave sensing, and lead impedance between the two sites.In the RVOT, 97% (34/35) of leads were placed on the septum, whereas in the mid RV the value was 89% (56/63). The study confirms that conventional active-fixation pacing leads can be successfully and safely deployed onto the RV septum using a purposely-shaped stylet guided only by the PA fluoroscopic projection.

Increased myosin heavy chain-beta with atrial expression of ventricular light chain-2 in canine cardiomyopathy.

PubMed

Fuller, Geraldine A; Bicer, Sabahattin; Hamlin, Robert L; Yamaguchi, Mamoru; Reiser, Peter J

2007-10-01

Dilated cardiomyopathy is a naturally occurring disease in humans and dogs. Human studies have shown increased levels of myosin heavy chain (MHC)-beta in failing ventricles and the left atria (LA) and of ventricular light chain (VLC)-2 in the right atria in dilated cardiomyopathy. This study evaluates the levels of MHC-beta in all heart chambers in prolonged canine right ventricular pacing. In addition, we determined whether levels of VLC2 were altered in these hearts. Failing hearts demonstrated significantly increased levels of MHC-beta in the right atria, right atrial appendage, LA, left atrial appendage (LAA), and right ventricle compared with controls. Significant levels of VLC2 were detected in the right atria of paced hearts. Differences in MHC-beta expression were observed between the LA and the LAA of paced and control dogs. MHC-beta expression was significantly greater in the LA of paced and control dogs compared with their respective LAA. The cardiac myosin isoform shifts in this study were similar to those observed in end-stage human heart failure and more severe than those reported in less prolonged pacing models, supporting the use of this model for further study of end-stage human heart failure. The observation of consistent differences between sampling sites, especially LA versus LAA, indicates the need for rigorous sampling consistency in future studies.

Alterations in left ventricular diastolic function in conscious dogs with pacing-induced heart failure

NASA Technical Reports Server (NTRS)

Komamura, K.; Shannon, R. P.; Pasipoularides, A.; Ihara, T.; Lader, A. S.; Patrick, T. A.; Bishop, S. P.; Vatner, S. F.

1992-01-01

We investigated in conscious dogs (a) the effects of heart failure induced by chronic rapid ventricular pacing on the sequence of development of left ventricular (LV) diastolic versus systolic dysfunction and (b) whether the changes were load dependent or secondary to alterations in structure. LV systolic and diastolic dysfunction were evident within 24 h after initiation of pacing and occurred in parallel over 3 wk. LV systolic function was reduced at 3 wk, i.e., peak LV dP/dt fell by -1,327 +/- 105 mmHg/s and ejection fraction by -22 +/- 2%. LV diastolic dysfunction also progressed over 3 wk of pacing, i.e., tau increased by +14.0 +/- 2.8 ms and the myocardial stiffness constant by +6.5 +/- 1.4, whereas LV chamber stiffness did not change. These alterations were associated with increases in LV end-systolic (+28.6 +/- 5.7 g/cm2) and LV end-diastolic stresses (+40.4 +/- 5.3 g/cm2). When stresses and heart rate were matched at the same levels in the control and failure states, the increases in tau and myocardial stiffness were no longer observed, whereas LV systolic function remained depressed. There were no increases in connective tissue content in heart failure. Thus, pacing-induced heart failure in conscious dogs is characterized by major alterations in diastolic function which are reversible with normalization of increased loading condition.

Validation of a novel mapping system and utility for mapping complex atrial tachycardias.

PubMed

Honarbakhsh, S; Hunter, R J; Dhillon, G; Ullah, W; Keating, E; Providencia, R; Chow, A; Earley, M J; Schilling, R J

2018-03-01

This study sought to validate a novel wavefront mapping system utilizing whole-chamber basket catheters (CARTOFINDER, Biosense Webster). The system was validated in terms of (1) mapping atrial-paced beats and (2) mapping complex wavefront patterns in atrial tachycardia (AT). Patients undergoing catheter ablation for AT and persistent AF were included. A 64-pole-basket catheter was used to acquire unipolar signals that were processed by CARTOFINDER mapping system to generate dynamic wavefront propagation maps. The left atrium was paced from four sites to demonstrate focal activation. ATs were mapped with the mechanism confirmed by conventional mapping, entrainment, and response to ablation. Twenty-two patients were included in the study (16 with AT and 6 with AF initially who terminated to AT during ablation). In total, 172 maps were created with the mapping system. It correctly identified atrial-pacing sites in all paced maps. It accurately mapped 9 focal/microreentrant and 18 macroreentrant ATs both in the left and right atrium. A third and fourth observer independently identified the sites of atrial pacing and the AT mechanism from the CARTOFINDER maps, while being blinded to the conventional activation maps. This novel mapping system was effectively validated by mapping focal activation patterns from atrial-paced beats. The system was also effective in mapping complex wavefront patterns in a range of ATs in patients with scarred atria. The system may therefore be of practical use in the mapping and ablation of AT and could have potential for mapping wavefront activations in AF. © 2018 Wiley Periodicals, Inc.

Mapping of the left-sided phrenic nerve course in patients undergoing left atrial catheter ablations.

PubMed

Huemer, Martin; Wutzler, Alexander; Parwani, Abdul S; Attanasio, Philipp; Haverkamp, Wilhelm; Boldt, Leif-Hendrik

2014-09-01

Catheter ablation of atrial fibrillation has been associated with left-sided phrenic nerve palsy. Knowledge of the individual left phrenic nerve course therefore is essential to prevent nerve injury. The aim of this study was to test the feasibility of an intraprocedural pace mapping and reconstruction of the left phrenic nerve course and to characterize which anatomical areas are affected. In patients undergoing left atrial catheter ablation, a three-dimensional map of the left atrial anatomical structures was created. The left-sided phrenic nerve course was determined by high-output pace mapping and reconstructed in the map. In this study, 40 patients with atrial fibrillation or atrial tachycardias were included. Left phrenic nerve capture was observed in 23 (57.5%) patients. Phrenic nerve was captured in 22 (55%) patients inside the left atrial appendage, in 22 (55%) in distal parts, in 21 (53%) in medial parts, and in two (5%) in ostial parts of the appendage. In three (7.5%) patients, capture was found in the distal coronary sinus and in one (2.5%) patient in the left atrium near the left atrial appendage ostium. Ablation target was changed due to direct spatial relationship to the phrenic nerve in three (7.5%) patients. No phrenic nerve palsy was observed. Left-sided phrenic nerve capture was found inside and around the left atrial appendage in the majority of patients and additionally in the distal coronary sinus. Phrenic nerve mapping and reconstruction can easily be performed and should be considered prior catheter ablations in potential affected areas. ©2014 Wiley Periodicals, Inc.

Loss of pace capture on the ablation line: a new marker for complete radiofrequency lesions to achieve pulmonary vein isolation.

PubMed

Steven, Daniel; Reddy, Vivek Y; Inada, Keiichi; Roberts-Thomson, Kurt C; Seiler, Jens; Stevenson, William G; Michaud, Gregory F

2010-03-01

Catheter ablation procedures for atrial fibrillation (AF) often involve circumferential antral isolation of pulmonary veins (PV). Inability to reliably identify conduction gaps on the ablation line necessitates placing additional lesions within the intended lesion set. This pilot study investigated the relationship between loss of pace capture directly along the ablation line and electrogram criteria for PV isolation (PVI). Using a 3-dimensional anatomic mapping system and irrigated-tip radiofrequency (RF) ablation catheter, lesions were placed in the PV antra to encircle ipsilateral vein pairs until pace capture at 10 mA/2 ms no longer occurred along the line. During ablation, a circular mapping catheter was placed in an ipsilateral PV, but the electrograms were not revealed until loss-of-pace capture. The procedural end point was PVI (entrance and exit block). Thirty patients (57 +/- 12 years; 15 male [50%]) undergoing PVI in 2 centers (3 primary operators) were included (left atrial diameter 40 +/- 4 mm, left ventricular ejection fraction 60 +/- 7%). All patients reached the end points of complete PVI and loss of pace capture. When PV electrograms were revealed after loss of pace capture along the line, PVI was present in 57 of 60 (95%) vein pairs. In the remaining 3 of 60 (5%) PV pairs, further RF applications achieved PVI. The procedure duration was 237 +/- 46 minutes, with a fluoroscopy time of 23 +/- 9 minutes. Analysis of the blinded PV electrograms revealed that even after PVI was achieved, additional sites of pace capture were present on the ablation line in 30 of 60 (50%) of the PV pairs; 10 +/- 4 additional RF lesions were necessary to fully achieve loss of pace capture. After ablation, the electrogram amplitude was lower at unexcitable sites (0.25 +/- 0.15 mV vs. 0.42 +/- 0.32 mV, P < .001), but there was substantial overlap with pace capture sites, suggesting that electrogram amplitude lacks specificity for identifying pace capture sites. Complete loss of pace capture directly along the circumferential ablation line correlates with entrance block in 95% of vein pairs and can be achieved without circular mapping catheter guidance. Thus, pace capture along the ablation line can be used to identify conduction gaps. Interestingly, more RF ablation energy was required to achieve loss of pace capture along the ablation line than for entrance block into PVs. Further study is warranted to determine whether this method results in more durable ablation lesions that reduce recurrence of AF. Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Right paracardiac mass due to organized pericardial hematoma around retained epicardial pacing wires following aortic valve replacement.

PubMed

Kapoor, Aditya; Syal, Sanjiv; Gupta, Nirmal; Gupta, Archana

2011-07-01

The use of temporary epicardial pacing wires during cardiac surgery is a routine procedure and has been associated with low morbidity. We describe a rare case of right paracardiac mass due to organized pericardial hematoma with right atrial compression around the epicardial pacing wires left in-situ, presenting three months following aortic valve replacement surgery. The case highlights the fact that such delayed complications can rarely occur around retained epicardial pacing wires following open heart surgery especially in patients on oral anticoagulants. The clinician should be alert to such an occurrence and during follow-up echocardiography always pay attention not only to the valve and ventricular function, but also to the pericardial and extra-pericardial space.

Effect of renal sympathetic denervation on the progression of paroxysmal atrial fibrillation in canines with long-term intermittent atrial pacing.

PubMed

Wang, Xule; Huang, Congxin; Zhao, Qingyan; Huang, He; Tang, Yanhong; Dai, Zixuan; Wang, Xiaozhan; Guo, Zongwen; Xiao, Jinping

2015-04-01

The aim of the present study was to explore the effect of renal sympathetic denervation (RSD) on the progression of paroxysmal atrial fibrillation (AF) in canines with long-term intermittent atrial pacing. Nineteen beagles were randomly divided into sham-operated group (six dogs), control group (six dogs), and RSD group (seven dogs). Sham-operated group were implanted with pacemakers without pacing; control group were implanted with pacemakers with long-term intermittent atrial pacing; and RSD group underwent catheter-based RSD bilaterally and were simultaneously implanted with pacemakers. Atrial pacing was maintained for 8 h a day and a total of 12 weeks in the control group and RSD group. Echocardiography showed that the left atrial structure and function were significantly improved in the RSD group compared with the control group (P < 0.05). Compared with the control group, the RSD group had fewer incidences of AF and a shorter duration of AF (P < 0.05) after long-term intermittent atrial pacing. In addition to increased atrial effective refractory period (AERP) and AF cycle length, AERP dispersion and P-wave duration and dispersion were significantly decreased in the RSD group compared with the control group (P < 0.05). Atrial morphological evaluation suggested that fibrosis and ultrastructural changes induced by long-term intermittent atrial pacing were markedly suppressed in the RSD dogs compared with controls (P < 0.05). Immunohistochemistry results showed that connexin 43 distribution in RSD mid-myocardial was significantly fewer heterogeneous than that in control mid-myocardial (P < 0.05). Renal denervation inhibits the progression of paroxysmal AF, which might be related to the suppression of atrial electrophysiology and structural heterogeneity. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Accuracy of piezoelectric pedometer and accelerometer step counts.

PubMed

Cruz, Joana; Brooks, Dina; Marques, Alda

2017-04-01

This study aimed to assess step-count accuracy of a piezoeletric pedometer (Yamax PW/EX-510), when worn at different body parts, and a triaxial accelerometer (GT3X+), and to compare device accuracy; and identify the preferred location(s) to wear a pedometer. Sixty-three healthy adults (45.8±20.6 years old) wore 7 pedometers (neck, lateral right and left of the waist, front right and left of the waist, front pockets of the trousers) and 1 accelerometer (over the right hip), while walking 120 m at slow, self-preferred/normal and fast paces. Steps were recorded. Participants identified their preferred location(s) to wear the pedometer. Absolute percent error (APE) and Bland and Altman (BA) method were used to assess device accuracy (criterion measure: manual counts) and BA method for device comparisons. Pedometer APE was below 3% at normal and fast paces despite wearing location, but higher at slow pace (4.5-9.1%). Pedometers were more accurate at the front waist and inside the pockets. Accelerometer APE was higher than pedometer APE (P<0.05); nevertheless, limits of agreement between devices were relatively small. Preferred wearing locations were inside the front right (N.=25) and left (N.=20) pockets of the trousers. Yamax PW/EX-510 pedometers may be preferable than GT3X+ accelerometers to count steps, as they provide more accurate results. These pedometers should be worn at the front right or left positions of the waist or inside the front pockets of the trousers.

Dynamic Changes of QRS Morphology of Premature Ventricular Contractions During Ablation in the Right Ventricular Outflow Tract: A Case Report.

PubMed

Yue-Chun, Li; Jia-Feng, Lin; Jia-Xuan, Lin

2015-10-01

Electrocardiographic characteristics can be useful in differentiating between right ventricular outflow tract (RVOT) and aortic sinus cusp (ASC) ventricular arrhythmias. Ventricular arrhythmias originating from ASC, however, show preferential conduction to RVOT that may render the algorithms of electrocardiographic characteristics less reliable. Even though there are few reports describing ventricular arrhythmias with ASC origins and endocardial breakout sites of RVOT, progressive dynamic changes in QRS morphology of the ventricular arrhythmias during ablation obtained were rare.This case report describes a patient with symptomatic premature ventricular contractions of left ASC origin presenting an electrocardiogram (ECG) characteristic of right ventricular outflow tract before ablation. Pacing at right ventricular outflow tract reproduced an excellent pace map. When radiofrequency catheter ablation was applied to the right ventricular outflow tract, the QRS morphology of premature ventricular contractions progressively changed from ECG characteristics of right ventricular outflow tract origin to ECG characteristics of left ASC origin.Successful radiofrequency catheter ablation was achieved at the site of the earliest ventricular activation in the left ASC. The distance between the successful ablation site of the left ASC and the site with an excellent pace map of the RVOT was 20 mm.The ndings could be strong evidence for a preferential conduction via the myocardial bers from the ASC origin to the breakout site in the right ventricular outflow tract. This case demonstrates that ventricular arrhythmias with a single origin and exit shift may exhibit QRS morphology changes.

Further evidence for the role of gap junctions in the delayed antiarrhythmic effect of cardiac pacing.

PubMed

Miskolczi, Gottfried; Gönczi, Márton; Kovács, Mária; Seprényi, György; Végh, Ágnes

2015-07-01

The objective of this study was to provide evidence that gap junctions are involved in the delayed antiarrhythmic effect of cardiac pacing. Twenty-four dogs were paced through the right ventricle (4 × 5 min, rate of 240 beats/min) 24 h prior to a 25 min occlusion of the left anterior descending coronary artery. Some of these paced dogs were infused with 50 (n = 7) or 100 μmol/L (n = 7) of the gap junction uncoupler carbenoxolone (CBX), prior to and during the occlusion. Ten sham-paced dogs, subjected only to occlusion, served as the controls. Cardiac pacing markedly reduced the number of ectopic beats and episodes of ventricular tachycardia (VT), as well the incidence of VT and ventricular fibrillation during occlusion. The changes in severity of ischaemia and tissue electrical resistance were also less marked compared with the unpaced controls. Pacing also preserved the permeability of gap junctions, the phosphorylation of connexin43, and the structural integrity of the intercalated discs. The closing of gap junctions with CBX prior to and during ischaemia markedly attenuated or even abolished these protective effects of pacing. Our results support the previous findings that gap junctions play a role in the delayed antiarrhythmic effect of cardiac pacing.

Implantation of active fixation leads in coronary veins for left ventricular stimulation: report of five cases.

PubMed

Hansky, Bert; Vogt, Juergen; Gueldner, Holger; Schulte-Eistrup, Sebastian; Lamp, Barbara; Heintze, Johannes; Horstkotte, Dieter; Koerfer, Reiner

2007-01-01

Securing transvenous left ventricular (LV) pacing leads without an active fixation mechanism in proximal coronary vein (CV) segments is usually challenging and frequently impossible. We investigated how active fixation leads can be safely implanted in this location, how to avoid perforating the free wall of the CV, and how to recognize and respond to perforations. In five patients with no alternative to LV pacing from proximal CV segments, 4 Fr SelectSecure (Medtronic, Minneapolis, MN, USA) leads, which have a fixed helix, were implanted through a modified 6 Fr guide catheter with a pre-shaped tip (Launcher, Medtronic). Active fixation leads were successfully implanted in proximal CVs in five patients. There were no complications. Acute and chronic pacing thresholds were comparable to those of conventional CV leads. The pre-shaped guide catheter tip remains in close proximity to the myocardial aspect of the CV, directing the lead helix toward a safe implantation site. If only proximal CV pacing sites are available, 4 Fr SelectSecure leads can be safely implanted through a modified Launcher guide catheter, avoiding more invasive implantation techniques. Other than venous stenting or implantation of leads with retractable tines, SelectSecure leads are expected to remain extractable.

Occurrence of simultaneous cathodal-anodal capture with left ventricular quadripolar leads for cardiac resynchronization therapy: an electrocardiogram evaluation.

PubMed

Occhetta, Eraldo; Dell'Era, Gabriele; Giubertoni, Ailia; Magnani, Andrea; Rametta, Francesco; Blandino, Alessandro; Magnano, Vincenzo; Malacrida, Maurizio; Marino, Paolo

2017-04-01

The occurrence of left ventricular (LV) anodal activation during pacing with modern multipolar cardiac resynchronization therapy (CRT) systems has never been reported. The aim of our study was to demonstrate, by means of electrocardiogram (ECG) analysis, the occurrence of simultaneous cathodal-anodal LV capture with quadripolar LV leads. We studied 10 first-time recipients of a CRT device equipped with a quadripolar LV lead. During follow-up, standard supine 12-lead ECGs were obtained in available cathode-to-anode LV pacing configurations with a pulse amplitude equal to twice the pacing threshold. The occurrence of simultaneous cathodal-anodal LV capture was defined as the presence of variations in electrocardiographic ventricular activation (EVA) when the distal tip (cathode)-to-device can (anode) pacing configuration was compared with the distal tip (cathode)-to-proximal ring (anode) configuration. In eight patients, we found differences in EVA when different LV sites were paced through the unipolar LV tip and unipolar LV ring configurations. In these patients, a difference in EVA was detected in 61.5% (59 of 96) of the ECG leads (marked difference in 31.3%, slight difference in 30.2%). Changes in EVA between unipolar tip-to-can and bipolar tip-to-ring pacing that were suggestive of cathodal-anodal LV capture were found in six patients. In these patients, a total of 30 (41.7%) ECG leads showed a difference in EVA (marked difference in 20.8%, slight difference in 20.8%). In our experience, additional anodal capture by the proximal LV ring during LV pacing is provable in most recipients of a resynchronization device equipped with a multipolar LV lead. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Accelerated graft dysfunction in heart transplant patients with persistent atrioventricular conduction block.

PubMed

Lee, William; Tay, Andre; Walker, Bruce D; Kuchar, Dennis L; Hayward, Christopher S; Spratt, Phillip; Subbiah, Rajesh N

2016-12-01

Bradyarrhythmia following heart transplantation is common-∼7.5-24% of patients require permanent pacemaker (PPM) implantation. While overall mortality is similar to their non-paced counterparts, the effects of chronic right ventricular pacing (CRVP) in heart transplant patients have not been studied. We aim to examine the effects of CRVP on heart failure and mortality in heart transplant patients. Records of heart transplant recipients requiring PPM at St Vincent's Hospital, Sydney, Australia between January 1990 and January 2015 were examined. Patient's without a right ventricular (RV) pacing lead or a follow-up time of <1 year were excluded. Patients with pre-existing abnormal left ventricular function (<50%) were analysed separately. Patients were grouped by pacing dependence (100% pacing dependent vs. non-pacing dependent). The primary endpoint was clinical or echocardiographic heart failure (<35%) in the first 5 years post-PPM. Thirty-three of 709 heart transplant recipients were studied. Two patients had complete RV pacing dependence, and the remaining 31 patients had varying degrees of pacing requirement, with an underlying ventricular escape rhythm. The primary endpoint occurred significantly more in the pacing-dependent group; 2 (100%) compared with 2 (6%) of the non pacing dependent group (P < 0.0001 by log-rank analysis, HR = 24.58). Non-pacing-dependent patients had reversible causes for heart failure, unrelated to pacing. In comparison, there was no other cause of heart failure in the pacing-dependent group. Permanent atrioventricular block is rare in the heart transplant population. We have demonstrated CRVP as a potential cause of accelerated graft failure in pacing-dependent heart transplant patients. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Decreased Number of Self-Paced Saccades in Post-Concussion Syndrome Associated with Higher Symptom Burden and Reduced White Matter Integrity.

PubMed

Taghdiri, Foad; Chung, Jonathan; Irwin, Samantha; Multani, Namita; Tarazi, Apameh; Ebraheem, Ahmed; Khodadadi, Mozghan; Goswami, Ruma; Wennberg, Richard; Mikulis, David; Green, Robin; Davis, Karen; Tator, Charles; Eizenman, Moshe; Tartaglia, Maria Carmela

2018-03-01

The aim of this study was to examine the potential utility of a self-paced saccadic eye movement as a marker of post-concussion syndrome (PCS) and monitoring the recovery from PCS. Fifty-nine persistently symptomatic participants with at least two concussions performed the self-paced saccade (SPS) task. We evaluated the relationships between the number of SPSs and 1) number of self-reported concussion symptoms, and 2) integrity of major white matter (WM) tracts (as measured by fractional anisotropy [FA] and mean diffusivity) that are directly or indirectly involved in saccadic eye movements and often affected by concussion. These tracts included the uncinate fasciculus (UF), cingulum (Cg) and its three subcomponents (subgenual, retrosplenial, and parahippocampal), superior longitudinal fasciculus, and corpus callosum. Mediation analyses were carried out to examine whether specific WM tracts (left UF and left subgenual Cg) mediated the relationship between the number of SPSs and 1) interval from last concussion or 2) total number of self-reported symptoms. The number of SPSs was negatively correlated with the total number of self-reported symptoms (r = -0.419, p = 0.026). The number of SPSs were positively correlated with FA of left UF and left Cg (r = 0.421, p = 0.013 and r = 0.452, p = 0.008; respectively). FA of the subgenual subcomponent of the left Cg partially mediated the relationship between the total number of symptoms and the number of SPSs, while FA of the left UF mediated the relationship between interval from last concussion and the number of SPSs. In conclusion, SPS testing as a fast and objective assessment may reflect symptom burden in patients with PCS. In addition, since the number of SPSs is associated with the integrity of some WM tracts, it may be useful as a diagnostic biomarker in patients with PCS.

Changes in left ventricular repolarization and ion channel currents following a transient rate increase superimposed on bradycardia in anesthetized dogs.

PubMed

Rubart, M; Lopshire, J C; Fineberg, N S; Zipes, D P

2000-06-01

We previously demonstrated in dogs that a transient rate increase superimposed on bradycardia causes prolongation of ventricular refractoriness that persists for hours after resumption of bradycardia. In this study, we examined changes in membrane currents that are associated with this phenomenon. The whole cell, patch clamp technique was used to record transmembrane voltages and currents, respectively, in single mid-myocardial left ventricular myocytes from dogs with 1 week of complete AV block; dogs either underwent 1 hour of left ventricular pacing at 120 beats/min or did not undergo pacing. Pacing significantly heightened mean phase 1 and peak plateau amplitudes by approximately 6 and approximately 3 mV, respectively (P < 0.02), and prolonged action potential duration at 90% repolarization from 235+/-8 msec to 278+/-8 msec (1 Hz; P = 0.02). Rapid pacing-induced changes in transmembrane ionic currents included (1) a more pronounced cumulative inactivation of the 4-aminopyridine-sensitive transient outward K+ current, Ito, over the range of physiologic frequencies, resulting from a approximately 30% decrease in the population of quickly reactivating channels; (2) increases in peak density of L-type Ca2+ currents, I(Ca.L), by 15% to 35 % between +10 and +60 mV; and (3) increases in peak density of the Ca2+-activated chloride current, I(Cl.Ca), by 30% to 120% between +30 and +50 mV. Frequency-dependent reduction in Ito combined with enhanced I(Ca.L) causes an increase in net inward current that may be responsible for the observed changes in ventricular repolarization. This augmentation of net cation influx is partially antagonized by an increase in outward I(Ca.Cl).

Occurrence of phrenic nerve stimulation in cardiac resynchronization therapy patients: the role of left ventricular lead type and placement site.

PubMed

Biffi, Mauro; Exner, Derek V; Crossley, George H; Ramza, Brian; Coutu, Benoit; Tomassoni, Gery; Kranig, Wolfgang; Li, Shelby; Kristiansen, Nina; Voss, Frederik

2013-01-01

Unwanted phrenic nerve stimulation (PNS) has been reported in ∼1 in 4 patients undergoing left ventricular (LV) pacing. The occurrence of PNS over mid-term follow-up and the significance of PNS are less certain. Data from 1307 patients enrolled in pre-market studies of LV leads manufactured by Medtronic (models 4193 and 4195 unipolar, 4194, 4196, 4296, and 4396 bipolar) were pooled. Left ventricular lead location was recorded at implant using a common classification scheme. Phrenic nerve stimulation symptoms were either spontaneously reported or identified at scheduled follow-up visits. A PNS-related complication was defined as PNS resulting in invasive intervention or the termination of LV pacing. Average follow-up was 14.9 months (range 0.0-46.6). Phrenic nerve stimulation symptoms occurred in 169 patients (12.9%). Phrenic nerve stimulation-related complications occurred in 21 of 1307 patients (1.6%); 16 of 738 (2.2%) in the unipolar lead studies, and 5 of 569 (0.9%) in the bipolar lead studies (P = 0.08). Phrenic nerve stimulation was more frequent at middle-lateral/posterior, and apical LV sites (139/1010) vs. basal-posterior/lateral/anterior, and middle-anterior sites (20/297; P= 0.01). As compared with an anterior LV lead position, a lateral LV pacing site was associated with over a four-fold higher risk of PNS (P= 0.005) and an apical LV pacing site was associated with over six-fold higher risk of PNS (P= 0.001). Phrenic nerve stimulation occurred in 13% of patients undergoing LV lead placement and was more common at mid-lateral/posterior, and LV apical sites. Most cases (123/139; 88%) of PNS were mitigated via electrical reprogramming, without the need for invasive intervention.

Acute hemodynamic effects of right and left ventricular lead positions during the implantation of cardiac resynchronization therapy defibrillators.

PubMed

Stockinger, Jochem; Staier, Klaus; Schiebeling-Römer, Jochen; Keyl, Cornelius

2011-11-01

To evaluate the acute hemodynamic effects of different right (RV) and left ventricular (LV) pacing sites in patients undergoing the implantation of a cardiac resynchronization therapy defibrillator (CRT-D). Stroke volume index (SVI), assessed via pulse contour analysis, and dp/dt max, obtained in the abdominal aorta, were analyzed in 21 patients with New York Heart Association class III heart failure and left bundle branch block (mean ejection fraction of 24 ± 6%), scheduled for CRT-D implantation under general anesthesia. We compared the hemodynamic effects of RV apical (A), RV septal (B), and biventricular pacing using the worst (lowest SVI; C) and best (highest SVI; D) coronary sinus lead positions. Mean arterial pressure, SVI, and dp/dt max did not differ significantly between RV apical and septal pacing. Dp/dt max and SVI increased significantly during biventricular pacing (dp/dt max: B, 588 ± 160 mmHg/s; C, 651 ± 218 mmHg/s, P = 0.03 vs B; D, 690 ± 220 mmHg/s, P = 0.02 vs C; SVI: B, 33.6 ± 5.5 mL/m², C, 34.8 ± 6.1 mL/m², P = 0.08 vs B, D 36.0 ± 6.0 mL/m², P < 0.001 vs C). The best hemodynamic response was associated with lateral or inferior lead positions in 15 patients. Other LV lead positions were most effective in six patients. The optimal LV lead position varies significantly among patients and should be individually determined during CRT-D implantation. The impact of the RV stimulation site in patients with intraventricular conduction delay, undergoing CRT-D implantation, has to be investigated in further studies.

Permanent His-bundle pacing: a systematic literature review and meta-analysis.

PubMed

Zanon, Francesco; Ellenbogen, Kenneth A; Dandamudi, Gopi; Sharma, Parikshit S; Huang, Weijian; Lustgarten, Daniel L; Tung, Roderick; Tada, Hiroshi; Koneru, Jayanthi N; Bergemann, Tracy; Fagan, Dedra H; Hudnall, John Harrison; Vijayaraman, Pugazhendhi

2018-04-26

Permanent cardiac pacing of the His-bundle restores and retains normal electrical activation of the ventricles. Data on His-bundle pacing (HBP) are largely limited to small single-centre reports, and clinical benefits and risks have not been systematically examined. We sought to systematically examine published studies of patients undergoing permanent HBP and quantify the benefits and risks of the therapy. PubMed, Embase, and Cochrane Library were searched for full-text articles on permanent HBP. Clinical outcomes of interest included implant success rate, procedural and lead complications, pacing thresholds, QRS duration, and ejection fraction at follow-up, and mortality. Data were extracted and summarized. Where possible, meta-analysis of aggregate data was performed. Out of 2876 articles, 26 met the inclusion criteria representing 1438 patients with an implant attempt. Average age of patients was 73 years and 62.1% were implanted due to atrioventricular block. Overall average implant success rate was 84.8% and was higher with use of catheter-delivered systems (92.1%; P < 0.001). Average pacing thresholds were 1.71 V at implant and 1.79 V at >3 months follow-up; although, pulse widths varied at testing. Average left ventricular ejection fractions (LVEFs) were 42.8% at baseline and 49.5% at follow-up. There were 43 complications observed in 907 patients across the 17 studies that reported safety information. Among 26 articles of permanent HBP, the implant success rate averaged 84.8% and LVEF improved by an average of 5.9% during follow-up. Specific reporting of our clinical outcomes of interest varied widely, highlighting the need for uniform reporting in future HBP trials.

Effects of ventricular rate and regularity on the velocity and magnitude of left atrial appendage flow in atrial fibrillation

PubMed Central

Obel, O A; Luddington, L; Maarouf, N; Aytemir, K; Ekwall, C; Malik, M; Camm, A J

2005-01-01

Objective: To prospectively determine whether ventricular rate and regularity are significant determinants of the velocity and magnitude of left atrial appendage (LAA) flow. Design and patients: 12 patients with atrial fibrillation (AF), high degree atrioventricular block, and indwelling permanent pacemakers were studied. Setting: Cardiology department of a tertiary referral centre. Interventions: Pacing was triggered by an external programmable transcutaneous device. Patients were paced at 60, 120, and 150 beats/min in both regular and irregular rhythm. LAA flow velocity and magnitude were assessed with transoesophageal Doppler echocardiography. Main outcome measures: Peak and mean LAA inflow and outflow velocity, and time-velocity interval (TVI) of LAA flow. Results: Increasing ventricular rate was associated with significantly lower peak inflow (p < 0.01), peak outflow (p < 0.05), mean inflow (p < 0.01), and mean outflow (p < 0.05) velocities and with a lower TVI of LAA filling and emptying velocities (p < 0.01). This effect was noted at rates of 60 beats/min compared with both 120 and 150 beats/min. At a pacing rate of 120 beats/min there was a significantly higher total TVI when pacing at a regular than at an irregular rhythm (40.16 (14.6) cm v 30.74 (10.9) cm, p < 0.05). Conclusions: In this study, LAA filling velocities in patients in AF were significantly influenced by paced ventricular rate and to a much lesser extent ventricular rhythm. These results suggest that rapid ventricular rates may predispose to stasis in the LAA in AF. PMID:15894771

A new intracavitary probe for detecting the site of origin of ectopic ventricular beats during one cardiac cycle.

PubMed

Taccardi, B; Arisi, G; Macchi, E; Baruffi, S; Spaggiari, S

1987-01-01

An olive-shaped probe (25 X 12 mm) with 41 evenly distributed recording electrodes on its surface was introduced into the left ventricles of seven open-chest dogs via the left atrium. In two other dogs a cylindrical probe (40 X 3 mm) was used. Electrical stimuli were delivered at 66 endocardial, midwall, or epicardial sites in the left and right ventricular walls and the septum. Mechanical stimuli were also applied at various epicardial sites. On-line mapping of equipotential contour lines on the surface of the probe invariably revealed a clear-cut potential minimum on the electrode that faced the pacing site. Time of appearance of potential minimum was 3 to 5 msec after endocardial stimuli, 10 to 25 msec for midwall and epicardial pacing, and 30 msec or more for right ventricular stimulation. Simultaneous stimulation at two sites 1.2 cm apart gave rise to two separate minima on the maps. "Pseudoisochrones" derived from electrograms recorded by the new probe were slightly less accurate in indicating the site of origin of extrasystoles. We conclude that equipotential and "isochrone" contour maps recorded from an array of semidirect electrodes, regularly distributed on the surface of an intraventricular probe, provide information on the site of origin (location and intramural depth) of ectopic paced beats in a normal dog heart.

The effect of running versus cycling high-intensity intermittent exercise on local tissue oxygenation and perceived enjoyment in 18–30-year-old sedentary men

PubMed Central

Solomon, Colin

2018-01-01

Background High-intensity interval training (HIIT) has been proposed as a time-efficient exercise format to improve exercise adherence, thereby targeting the chronic disease burden associated with sedentary behaviour. Exercise mode (cycling, running), if self-selected, will likely affect the physiological and enjoyment responses to HIIT in sedentary individuals. Differences in physiological and enjoyment responses, associated with the mode of exercise, could potentially influence the uptake and continued adherence to HIIT. It was hypothesised that in young sedentary men, local and systemic oxygen utilisation and enjoyment would be higher during a session of running HIIT, compared to a session of cycling HIIT. Methods A total of 12 sedentary men (mean ± SD; age 24 ± 3 years) completed three exercise sessions: a maximal incremental exercise test on a treadmill (MAX) followed by two experiment conditions, (1) free-paced cycling HIIT on a bicycle ergometer (HIITCYC) and (2) constant-paced running HIIT on a treadmill ergometer (HIITRUN). Deoxygenated haemoglobin (HHb) in the gastrocnemius (GN), the left vastus lateralis (LVL) and the right vastus lateralis (RVL) muscles, oxygen consumption (VO2), heart rate (HR), ratings of perceived exertion (RPE) and physical activity enjoyment (PACES) were measured during HIITCYC and HIITRUN. Results There was a higher HHb in the LVL (p = 0.001) and RVL (p = 0.002) sites and a higher VO2 (p = 0.017) and HR (p < 0.001) during HIITCYC, compared to HIITRUN. RPE was higher (p < 0.001) and PACES lower (p = 0.032) during HIITCYC compared to HIITRUN. Discussion In sedentary individuals, free-paced cycling HIIT produces higher levels of physiological stress when compared to constant-paced running HIIT. Participants perceived running HIIT to be more enjoyable than cycling HIIT. These findings have implications for selection of mode of HIIT for physical stress, exercise enjoyment and compliance.

The effect of running versus cycling high-intensity intermittent exercise on local tissue oxygenation and perceived enjoyment in 18-30-year-old sedentary men.

PubMed

Kriel, Yuri; Askew, Christopher D; Solomon, Colin

2018-01-01

High-intensity interval training (HIIT) has been proposed as a time-efficient exercise format to improve exercise adherence, thereby targeting the chronic disease burden associated with sedentary behaviour. Exercise mode (cycling, running), if self-selected, will likely affect the physiological and enjoyment responses to HIIT in sedentary individuals. Differences in physiological and enjoyment responses, associated with the mode of exercise, could potentially influence the uptake and continued adherence to HIIT. It was hypothesised that in young sedentary men, local and systemic oxygen utilisation and enjoyment would be higher during a session of running HIIT, compared to a session of cycling HIIT. A total of 12 sedentary men (mean ± SD; age 24 ± 3 years) completed three exercise sessions: a maximal incremental exercise test on a treadmill (MAX) followed by two experiment conditions, (1) free-paced cycling HIIT on a bicycle ergometer (HIITCYC) and (2) constant-paced running HIIT on a treadmill ergometer (HIITRUN). Deoxygenated haemoglobin (HHb) in the gastrocnemius (GN), the left vastus lateralis (LVL) and the right vastus lateralis (RVL) muscles, oxygen consumption (VO 2 ), heart rate (HR), ratings of perceived exertion (RPE) and physical activity enjoyment (PACES) were measured during HIITCYC and HIITRUN. There was a higher HHb in the LVL ( p = 0.001) and RVL ( p = 0.002) sites and a higher VO 2 ( p = 0.017) and HR ( p < 0.001) during HIITCYC, compared to HIITRUN. RPE was higher ( p < 0.001) and PACES lower ( p = 0.032) during HIITCYC compared to HIITRUN. In sedentary individuals, free-paced cycling HIIT produces higher levels of physiological stress when compared to constant-paced running HIIT. Participants perceived running HIIT to be more enjoyable than cycling HIIT. These findings have implications for selection of mode of HIIT for physical stress, exercise enjoyment and compliance.

Influence of pacing site characteristics on response to cardiac resynchronization therapy.

PubMed

Wong, Jorge A; Yee, Raymond; Stirrat, John; Scholl, David; Krahn, Andrew D; Gula, Lorne J; Skanes, Allan C; Leong-Sit, Peter; Klein, George J; McCarty, David; Fine, Nowell; Goela, Aashish; Islam, Ali; Thompson, Terry; Drangova, Maria; White, James A

2013-07-01

Transmural scar occupying left ventricular (LV) pacing regions has been associated with reduced response to cardiac resynchronization therapy (CRT). However, spatial influences of lead tip delivery relative to scar at both pacing sites remain poorly explored. This study evaluated scar distribution relative to LV and right ventricular (RV) lead tip placement through coregistration of late gadolinium enhancement MRI and cardiac computed tomographic (CT) findings. Influences on CRT response were assessed by serial echocardiography. Sixty patients receiving CRT underwent preimplant late gadolinium enhancement MRI, postimplant cardiac CT, and serial echocardiography. Blinded segmental evaluations of mechanical delay, percentage scar burden, and lead tip location were performed. Response to CRT was defined as a reduction in LV end-systolic volume ≥15% at 6 months. The mean age and LV ejection fraction were 64±9 years and 25±7%, respectively. Mean scar volume was higher among CRT nonresponders for both the LV (23±23% versus 8±14% [P=0.01]) and RV pacing regions (40±32% versus 24±30% [P=0.04]). Significant pacing region scar was identified in 13% of LV pacing regions and 37% of RV pacing regions. Absence of scar in both regions was associated with an 81% response rate compared with 55%, 25%, and 0%, respectively, when the RV, LV, or both pacing regions contained scar. LV pacing region dyssynchrony was not predictive of response. Myocardial scar occupying the LV pacing region is associated with nonresponse to CRT. Scar occupying the RV pacing region is encountered at higher frequency and seems to provide a more intermediate influence on CRT response.

[Multiple coronary fistulas to the left ventricle. An unusual cause of myocardial ischemia].

PubMed

Piovaccari, G; Melandri, G; Marzocchi, A; Scarfoglio, D; Sanguinetti, M; Magnani, B

1989-04-01

Diffuse communications between the left coronary artery and the left ventricular cavity were found in a 54-years-old man presenting with angina pectoris and reversible ischemia documented on stress Thallium scintigraphy. During atrial pacing the patient experienced chest pain which was accompanied by lactate production. Atenolol, but not nifedipine, did ameliorate the symptoms. The anatomical types and the embriogenesis of coronary microfistulas along with possible mechanisms of ischemia are discussed.

Complications with the MICRA TPS Pacemaker System: Persistent Complete Heart Block and Late Capture Failure.

PubMed

Holm, Niels; Müller, Andreas; Zbinden, Rainer

2017-04-01

A Medtronic MICRA transcatheter pacing system (Medtronic, Minneapolis, MN, USA) was implanted in an 86-year-old patient with sick sinus syndrome and left bundle branch block after transfemoral aortic valve implantation. During implantation she developed a persistent complete heart block due to manipulation with the large-bore delivery catheter. Two weeks later, acute pacemaker dysfunction occurred due to massive increase of pacing threshold and impedance without obvious pacemaker dislocation or myocardial perforation. Recurrent capture failure was seen with pacing output set at 5 V/1.0 ms. Hence, microdislocation or fixation of the tines in the right ventricular trabeculae has to be assumed. © 2016 Wiley Periodicals, Inc.

Atrioventricular and ventricular-to-ventricular programming in patients with cardiac resynchronization therapy: results from ALTITUDE.

PubMed

Steinberg, Benjamin A; Wehrenberg, Scott; Jackson, Kevin P; Hayes, David L; Varma, Niraj; Powell, Brian D; Day, John D; Frazier-Mills, Camille G; Stein, Kenneth M; Jones, Paul W; Piccini, Jonathan P

2015-12-01

Cardiac resynchronization therapy (CRT) improves outcomes in patients with heart failure, yet response rates are variable. We sought to determine whether physician-specified CRT programming was associated with improved outcomes. Using data from the ALTITUDE remote follow-up cohort, we examined sensed atrioventricular (AV) and ventricular-to-ventricular (VV) programming and their associated outcomes in patients with de novo CRT from 2009-2010. Outcomes included arrhythmia burden, left ventricular (LV) pacing, and all-cause mortality at 4 years. We identified 5709 patients with de novo CRT devices; at the time of implant, 34% (n = 1959) had entirely nominal settings programmed, 40% (n = 2294) had only AV timing adjusted, 11% (n = 604) had only VV timing adjusted, and 15% (n = 852) had both AV and VV adjusted from nominal programming. Suboptimal LV pacing (<95%) during follow-up was similar across groups; however, the proportion with atrial fibrillation (AF) burden >5% was lowest in the AV-only adjusted group (17.9%) and highest in the nominal (27.7%) and VV-only adjusted (28.3%) groups. Adjusted all-cause mortality was significantly higher among patients with non-nominal AV delay >120 vs. <120 ms (adjusted heart rate (HR) 1.28, p = 0.008) but similar when using the 180-ms cutoff (adjusted HR 1.13 for >180 vs. ≤180 ms, p = 0.4). Nominal settings for de novo CRT implants are frequently altered, most commonly the AV delay. There is wide variability in reprogramming. Patients with nominal or AV-only adjustments appear to have favorable pacing and arrhythmia outcomes. Sensed AV delays less than 120 ms are associated with improved survival.

Left bundle branch block, an old-new entity.

PubMed

Breithardt, Günter; Breithardt, Ole-Alexander

2012-04-01

Left bundle branch block (LBBB) is generally associated with a poorer prognosis in comparison to normal intraventricular conduction, but also in comparison to right bundle branch block which is generally considered to be benign in the absence of an underlying cardiac disorder like congenital heart disease. LBBB may be the first manifestation of a more diffuse myocardial disease. The typical surface ECG feature of LBBB is a prolongation of QRS above 0.11 s in combination with a delay of the intrinsic deflection in leads V5 and V6 of more than 60 ms and no septal q waves in leads I, V5, and V6 due to the abnormal septal activation from right to left. LBBB may induce abnormalities in left ventricular performance due to abnormal asynchronous contraction patterns which can be compensated by biventricular pacing (resynchronization therapy). Asynchronous electrical activation of the ventricles causes regional differences in workload which may lead to asymmetric hypertrophy and left ventricular dilatation, especially due to increased wall mass in late-activated regions, which may aggravate preexisting left ventricular pumping performance or even induce it. Of special interest are patients with LBBB and normal left ventricular dimensions and normal ejection fraction at rest but who may present with an abnormal increase in pulmonary artery pressure during exercise, production of lactate during high-rate pacing, signs of ischemia on myocardial scintigrams (but no coronary artery narrowing), and abnormal ultrastructural findings on myocardial biopsy. For this entity, the term latent cardiomyopathy had been suggested previously.

The Myocardial Ischemia Evaluated by Real-Time Contrast Echocardiography May Predict the Response to Cardiac Resynchronization Therapy: A Large Animal Study

PubMed Central

Chen, Yongle; Cheng, Leilei; Yao, Haohua; Chen, Haiyan; Wang, Yongshi; Zhao, Weipeng; Pan, Cuizhen; Shu, Xianhong

2014-01-01

Evidence-based criteria for applying cardiac resynchronization therapy (CRT) in patients with ischemic cardiomyopathy are still scarce. The aim of the present study was to evaluate the predictive value of real-time myocardial contrast echocardiography (RT-MCE) in a preclinical canine model of ischemic cardiomyopathy who received CRT. Ischemic cardiomyopathy was produced by ligating the first diagonal branch in 20 beagles. Dogs were subsequently divided into two groups that were either treated with bi-ventricular pacing (CRT group) or left untreated (control group). RT-MCE was performed at baseline, before CRT, and 4 weeks after CRT. Two-dimensional speckle tracking imaging was used to evaluate the standard deviation of circumferential (Cir12SD), radial (R12SD), and longitudinal (L12SD) strains of left ventricular segments at basal as well as middle levels. Four weeks later, the Cir12SD, R12SD, and myocardial blood flow (MBF) of the treated group were significantly improved compared to their non-CRT counterparts. Furthermore, MBF values measured before CRT were significantly higher in responders than in non-responders to bi-ventricular pacing. Meanwhile, no significant differences were observed between the responder and non-responder groups in terms of Cir12SD, R12SD, and L12SD. A high degree of correlation was found between MBF values before CRT and LVEF after CRT. When MBF value>24.9 dB/s was defined as a cut-off point before CRT, the sensitivity and specificity of RT-MCE in predicting the response to CRT were 83.3% and 100%, respectively. Besides, MBF values increased significantly in the CRT group compared with the control group after 4 weeks of pacing (49.8±15.5 dB/s vs. 28.5±4.6 dB/s, p<0.05). Therefore, we considered that myocardial perfusion may be superior to standard metrics of LV synchrony in selecting appropriate candidates for CRT. In addition, CRT can improve myocardial perfusion in addition to cardiac synchrony, especially in the setting of ischemic cardiomyopathy. PMID:25469632

Transdiaphragmatic pressure in quadriplegic individuals ventilated by diaphragmatic pacemaker.

PubMed Central

Garrido-García, H.; Martín-Escribano, P.; Palomera-Frade, J.; Arroyo, O.; Alonso-Calderón, J. L.; Mazaira-Alvarez, J.

1996-01-01

BACKGROUND: Electrophrenic pacing can be used in the management of ventilatory failure in quadriplegic patients. A study was undertaken to determine the pattern of transdiaphragmatic pressure (PDI) during the conditioning phase of electrophrenic pacing to see if it had a possible role in optimising the process of conditioning. METHODS: The tidal volume (TV) and PDI were measured in a group of six quadriplegic patients commencing ventilation by low frequency pulse stimulation (7-10 Hz) and low respiratory rate stimulation (< 10 breaths/min). RESULTS: Tidal volume increased between baseline and month 1 (4.33 ml/kg, p < 0.001) and between months 1 and 2 (3.00 ml/kg, p < 0.05) and then stabilised. PDI was higher during bilateral diaphragmatic pacing (mean (SD) 1.73 (0.30) kPa) than with either left (1.15 (0.34) kPa) or right (0.86 (0.37) kPa) unilateral pacing. PDI varied throughout the observation period, probably by interaction between recovery of the diaphragmatic fibres and the pacing regimen. CONCLUSIONS: Patients with quadriplegia due to high spinal injury can be maintained with ventilation by continuous electrophrenic pacing. The control criteria used in this study for pacing were tidal volume and the patient's tolerance, and the PDI measurement did not contribute any additional information to help with managing the conditioning process. PMID:8733497

Higher sympathetic nerve activity during ventricular (VVI) than during dual-chamber (DDD) pacing

NASA Technical Reports Server (NTRS)

Taylor, J. A.; Morillo, C. A.; Eckberg, D. L.; Ellenbogen, K. A.

1996-01-01

OBJECTIVES: We determined the short-term effects of single-chamber ventricular pacing and dual-chamber atrioventricular (AV) pacing on directly measured sympathetic nerve activity. BACKGROUND: Dual-chamber AV cardiac pacing results in greater cardiac output and lower systemic vascular resistance than does single-chamber ventricular pacing. However, it is unclear whether these hemodynamic advantages result in less sympathetic nervous system outflow. METHODS: In 13 patients with a dual-chamber pacemaker, we recorded the electrocardiogram, noninvasive arterial pressure (Finapres), respiration and muscle sympathetic nerve activity (microneurography) during 3 min of underlying basal heart rate and 3 min of ventricular and AV pacing at rates of 60 and 100 beats/min. RESULTS: Arterial pressure was lowest and muscle sympathetic nerve activity was highest at the underlying basal heart rate. Arterial pressure increased with cardiac pacing and was greater with AV than with ventricular pacing (change in mean blood pressure +/- SE: 10 +/- 3 vs. 2 +/- 2 mm Hg at 60 beats/min; 21 +/- 5 vs. 14 +/- 2 mm Hg at 100 beats/min; p < 0.05). Sympathetic nerve activity decreased with cardiac pacing and the decline was greater with AV than with ventricular pacing (60 beats/min -40 +/- 11% vs. -17 +/- 7%; 100 beats/min -60 +/- 9% vs. -48 +/- 10%; p < 0.05). Although most patients showed a strong inverse relation between arterial pressure and muscle sympathetic nerve activity, three patients with severe left ventricular dysfunction (ejection fraction < or = 30%) showed no relation between arterial pressure and sympathetic activity. CONCLUSIONS: Short-term AV pacing results in lower sympathetic nerve activity and higher arterial pressure than does ventricular pacing, indicating that cardiac pacing mode may influence sympathetic outflow simply through arterial baroreflex mechanisms. We speculate that the greater incidence of adverse outcomes in patients treated with single-chamber ventricular rather than dual-chamber pacing may be due in part to increased sympathetic nervous outflow.

Stimulation of ganglionated plexus attenuates cardiac neural remodeling and heart failure progression in a canine model of acute heart failure post-myocardial infarction.

PubMed

Luo, Da; Hu, Huihui; Qin, Zhiliang; Liu, Shan; Yu, Xiaomei; Ma, Ruisong; He, Wenbo; Xie, Jing; Lu, Zhibing; He, Bo; Jiang, Hong

2017-12-01

Heart failure (HF) is associated with autonomic dysfunction. Vagus nerve stimulation has been shown to improve cardiac function both in HF patients and animal models of HF. The purpose of this present study is to investigate the effects of ganglionated plexus stimulation (GPS) on HF progression and autonomic remodeling in a canine model of acute HF post-myocardial infarction. Eighteen adult mongrel male dogs were randomized into the control (n=8) and GPS (n=10) groups. All dogs underwent left anterior descending artery ligation followed by 6-hour high-rate (180-220bpm) ventricular pacing to induce acute HF. Transthoracic 2-dimensional echocardiography was performed at different time points. The plasma levels of norepinephrine, B-type natriuretic peptide (BNP) and Ang-II were measured using ELISA kits. C-fos and nerve growth factor (NGF) proteins expressed in the left stellate ganglion as well as GAP43 and TH proteins expressed in the peri-infarct zone were measured using western blot. After 6h of GPS, the left ventricular end-diastolic volume, end-systolic volume and ejection fraction showed no significant differences between the 2 groups, but the interventricular septal thickness at end-systole in the GPS group was significantly higher than that in the control group. The plasma levels of norepinephrine, BNP, Ang-II were increased 1h after myocardial infarction while the increase was attenuated by GPS. The expression of c-fos and NGF proteins in the left stellate ganglion as well as GAP43 and TH proteins in cardiac peri-infarct zone in GPS group were significantly lower than that in control group. GPS inhibits cardiac sympathetic remodeling and attenuates HF progression in canines with acute HF induced by myocardial infarction and ventricular pacing. Copyright © 2017 Elsevier B.V. All rights reserved.

Performance of Anatomically Designed Quadripolar Left Ventricular Leads: Results from the NAVIGATE X4 Clinical Trial.

PubMed

Mittal, Suneet; Nair, Devi; Padanilam, Benzy J; Ciuffo, Allen; Gupta, Nigel; Gallagher, Peter; Goldner, Bruce; Hammill, Eric F; Wold, Nicolas; Stein, Kenneth; Burke, Martin

2016-10-01

The safety and efficacy of a novel family of quadripolar left ventricular (LV) pacing leads designed to pace from nonapical regions of the LV with low pacing capture thresholds was studied in patients undergoing implantation of a cardiac resynchronization therapy defibrillator (CRT-D). Patients receiving a CRT-D were implanted with 1 of 3 ACUITY X4 leads (Spiral Long, Spiral Short, or Straight), designed to address coronary venous anatomical variability. Electrical performance and LV lead related complications were evaluated 3 and 6 months post implantation, respectively. 764 patients (68 ± 11 years, 66% male) were enrolled; 738 (97%) successfully implanted with an ACUITY X4 lead (Spiral L, n = 239, 31%; Spiral S, n = 281, 37%; Straight, n = 218, 29%). A targeted threshold ≤2.5 V was achieved in 644 (94%) patients. The median threshold from the best proximal electrode was lower than the tip electrode (0.9 V [IQR 0.7, 1.3] vs. 1.3 V [IQR 0.7, 2.5], p< 0.001) on Spiral leads. Irrespective of lead implanted, one of the proximal electrodes was the programmed cathode in most patients. The overall LV complication-free rate was 98%. LV lead dislodgment occurred in 8 (1%) patients. PNS occurred in 58 (8%) patients, but only 3 (0.4%) patients required surgical intervention. The ACUITY X4 LV leads had low pacing thresholds particularly from proximal electrodes, a high incidence of pacing from the nondistal electrode, and low likelihood of dislodgment or PNS requiring surgical intervention. (ClinicalTrials.gov Identifier: NCT02071173). © 2016 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals, Inc.

Effect of monopolar radiofrequency energy on pacemaker function.

PubMed

Govekar, Henry R; Robinson, Thomas N; Varosy, Paul D; Girard, Guillaume; Montero, Paul N; Dunn, Christina L; Jones, Edward L; Stiegmann, Greg V

2012-10-01

This study aimed to quantify the clinical parameters of mono- and bipolar instruments that inhibit pacemaker function. The specific aims were to quantify pacer inhibition resulting from the monopolar instrument by altering the generator power setting, the generator mode, the distance between the active electrode and the pacemaker, and the location of the dispersive electrode. A transvenous ventricular lead pacemaker overdrive paced the native heart rate of an anesthetized pig. The primary outcome variable was pacer inhibition quantified as the number of beats dropped by the pacemaker during 5 s of monopolar active electrode activation. Lowering the generator power setting from 60 to 30 W decreased the number of dropped paced events (2.3 ± 1.2 vs 1.6 ± 0.8 beats; p = 0.045). At 30 W of power, use of the cut mode decreased the number of dropped paced beats compared with the coagulation mode (0.6 ± 0.5 vs 1.6 ± 0.8; p = 0.015). At 30 W coagulation, firing the active electrode at different distances from the pacemaker generator (3.75, 7.5, 15, and 30 cm) did not change the number of dropped paced beats (p = 0.314, analysis of variance [ANOVA]). The dispersive electrode was placed in four locations (right/left gluteus, right/left shoulder). More paced beats were dropped when the current vector traveled through the pacemaker/leads than when it did not (1.5 ± 1.0 vs 0.2 ± 0.4; p < 0.001). Clinical parameters that reduce the inhibition of a pacemaker by monopolar instruments include lowering the generator power setting, using cut (vs coagulation) mode, and locating the dispersive electrode so the current vector does not traverse the pacemaker generator or leads.

Impact of high-grade Atrioventricular block and cumulative frequent pacing on atrial arrhythmias.

PubMed

Wali, Eisha; Deshmukh, Amrish; Bukari, Abdallah; Broman, Michael; Aziz, Zaid; Beaser, Andrew; Upadhyay, Gaurav; Nayak, Hemal M; Tung, Roderick; Ozcan, Cevher

2018-06-21

The relationship between high-grade AV block (HGAVB) with cumulative frequent pacing and risk of atrial arrhythmias (AAs) has not been well characterized. We hypothesized HGAVB and pacing may have significant impact on incidence and prevalence of AAs by modulating atrial substrate. To determine impact of HGAVB and pacing on AAs including atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT). All consecutive patients who underwent dual chamber pacemaker implantation for HGAVB from 2005 to 2011 at the University of Chicago were included. AAs and percent of pacing were detected through device interrogation. Patients' data were collected from electronic medical records and clinic visits. A total of 166 patients (mean age 71±15 years; 54% female, 56% African-American) were studied. AF was documented in 27% of patients before pacemaker implantation. During a mean 5.8±2.2 years of follow-up, 47% had device-detected AF, 10% AFL and 26% AT. New-onset AF was documented in 40 of the 122 patients without prior AF (33%). Continuous (≥99%) right ventricular pacing was associated with significantly decreased AF prevalence (34% versus 59%, p = 0.005), and correlated with lower incidence (26% versus 41%, p = 0.22). Pacing suppressed AF in 14% of patients with baseline AF; those patients had lower atrial pacing (3.2% versus 45%, p < 0.0001). Left atrial dilation was the only independent predictor of AF with frequent pacing (p = 0.009). HGAVB is associated with high incidence and prevalence of AAs with and without pacing. Cumulative frequent (≥99%) ventricular pacing reduces risk of AF in patients with HGAVB. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Efficiency of timing delays and electrode positions in optimization of biventricular pacing: a simulation study.

PubMed

Miri, Raz; Graf, Iulia M; Dössel, Olaf

2009-11-01

Electrode positions and timing delays influence the efficacy of biventricular pacing (BVP). Accordingly, this study focuses on BVP optimization, using a detailed 3-D electrophysiological model of the human heart, which is adapted to patient-specific anatomy and pathophysiology. The research is effectuated on ten heart models with left bundle branch block and myocardial infarction derived from magnetic resonance and computed tomography data. Cardiac electrical activity is simulated with the ten Tusscher cell model and adaptive cellular automaton at physiological and pathological conduction levels. The optimization methods are based on a comparison between the electrical response of the healthy and diseased heart models, measured in terms of root mean square error (E(RMS)) of the excitation front and the QRS duration error (E(QRS)). Intra- and intermethod associations of the pacing electrodes and timing delays variables were analyzed with statistical methods, i.e., t -test for dependent data, one-way analysis of variance for electrode pairs, and Pearson model for equivalent parameters from the two optimization methods. The results indicate that lateral the left ventricle and the upper or middle septal area are frequently (60% of cases) the optimal positions of the left and right electrodes, respectively. Statistical analysis proves that the two optimization methods are in good agreement. In conclusion, a noninvasive preoperative BVP optimization strategy based on computer simulations can be used to identify the most beneficial patient-specific electrode configuration and timing delays.

Alterations in myocardial free fatty acid clearance precede mechanical abnormalities in canine tachycardia-induced heart failure.

PubMed

Freeman, G L; Colston, J T; Miller, D D

1994-01-01

The purpose of this study was to evaluate whether abnormalities of free fatty acid metabolism are present before the onset of overt mechanical dysfunction in dogs with tachycardia-induced heart failure. We studied six dogs chronically instrumented to allow assessment of left ventricular function in the pressure-volume plane. Free fatty acid clearance was assessed according to the washout rate of a free fatty acid analog, iodophenylpentadecanoic acid ([123I]PPA or IPPA). IPPA clearance was measured within 1 hour of the hemodynamic assessment. The animals were studied under baseline conditions and 11.7 +/- 3.6 days after ventricular pacing at a rate of 240 beats/min. Hemodynamic studies after pacing showed a nonsignificant increase in left ventricular end-diastolic pressure (11.7 +/- 4.7 to 17.4 +/- 6.5 mm Hg) and a nonsignificant decrease in the maximum derivative of pressure with respect to time (1836 +/- 164 vs 1688 +/- 422 mm Hg/sec). There was also no change in the time constant of left ventricular relaxation, which was 34.8 +/- 7.67 msec before and 35.3 +/- 7.3 msec after pacing. However, a significant prolongation in the clearance half-time of [123I]PPA, from 86.1 +/- 23.9 to 146.5 +/- 22.6 minutes (p < 0.01) was found. Thus abnormal lipid clearance appears before the onset of significant mechanical dysfunction in tachycardia-induced heart failure. This suggests that abnormal substrate metabolism may play an important role in the pathogenesis of this condition.

Potential role of biventricular pacing beyond advanced systolic heart failure.

PubMed

Fang, Fang; Sanderson, John E; Yu, Cheuk-Man

2013-01-01

Cardiac resynchronization therapy (CRT) is an effective therapy for advanced heart failure (HF) patients. The indications are well defined in recent guidelines and broadly indicate that CRT is suitable for chronic HF patients with left ventricular ejection fraction (EF) ≤35% and in NYHA class III or IV (Class I), and those with prolonged QRS duration ≥120 ms with left bundle branch block (LBBB) QRS morphology, or QRS duration ≥150 ms irrespective of QRS morphology (Class IIa). For patients with NYHA class II symptoms, CRT is recommended for patients with EF ≤30% and QRS duration ≥130 ms with LBBB QRS morphology (Class I, level of evidence: A), or QRS duration ≥150 ms irrespective of QRS morphology (Class IIa, level of evidence: A). However, CRT may benefit additional patients outside these criteria. In this review, we summarize the role of CRT in some subgroups, including patients with mild and moderate HF, upgrading to CRT from right ventricular (RV) pacing, bradycardia patients with routine pacing indications, congenital heart disease and specific cardiomyopathies. It is possible that CRT can give symptomatic and mortality benefits in some of these subgroups in the future and further clinical trials are warranted.  

A Clinical Feasibility Study of Atrial and Ventricular Electromechanical Wave Imaging

PubMed Central

Provost, Jean; Gambhir, Alok; Vest, John; Garan, Hasan; Konofagou, Elisa E.

2014-01-01

Background Cardiac Resynchronization Therapy (CRT) and atrial ablation currently lack a noninvasive imaging modality for reliable treatment planning and monitoring. Electromechanical Wave Imaging (EWI) is an ultrasound-based method that has previously been shown to be capable of noninvasively and transmurally mapping the activation sequence of the heart in animal studies by estimating and imaging the electromechanical wave, i.e., the transient strains occurring in response to the electrical activation, at both very high temporal and spatial resolution. Objective Demonstrate the feasibility of noninvasive transthoracic EWI for mapping the activation sequence during different cardiac rhythms in humans. Methods EWI was performed in CRT patients with a left bundle-branch block (LBBB), during sinus rhythm, left-ventricular pacing, and right-ventricular pacing and in atrial flutter (AFL) patients before intervention and correlated with results from invasive intracardiac electrical mapping studies during intervention. Additionally, the feasibility of single-heartbeat EWI at 2000 frames/s, is demonstrated in humans for the first time in a subject with both AFL and right bundle-branch-block. Results The electromechanical activation maps demonstrated the capability of EWI to localize the pacing sites and characterize the LBBB activation sequence transmurally in CRT patients. In AFL patients, the propagation patterns obtained with EWI were in agreement with results obtained from invasive intracardiac mapping studies. Conclusion Our findings demonstrate the potential capability of EWI to aid in monitoring and follow-up of patients undergoing CRT pacing therapy and atrial ablation with preliminary validation in vivo. PMID:23454060

Value of right ventricular mapping in patients with postinfarction ventricular tachycardia.

PubMed

Yokokawa, Miki; Good, Eric; Crawford, Thomas; Chugh, Aman; Pelosi, Frank; Latchamsetty, Rakesh; Oral, Hakan; Morady, Fred; Bogun, Frank

2012-06-01

Postinfarction ventricular tachycardia (VT) typically involves the left ventricular endocardium. Right ventricular involvement in the arrhythmogenic substrate of postinfarction VT is considered unusual. To assess the role of right ventricular mapping and ablation in patients with prior septal myocardial infarction. From among 37 consecutive patients with recurrent postinfarction VT, 18 patients with evidence of left ventricular septal involvement of myocardial infarction were identified; these patients were the subjects of this report. In these 18 patients, 166 VTs (cycle length 372 ± 117 ms) were induced. Right ventricular voltage mapping was performed in all 18 patients with left ventricular septal myocardial infarction. Right ventricular voltage mapping showed areas of low voltage in 11 patients; pace mapping from these areas revealed matching pace maps for 17 VTs, and radiofrequency ablation from the right ventricular endocardium but not the left ventricular endocardium eliminated 14 of 17 VTs. VTs with critical components in the right ventricle had a left bundle branch block morphology that had similar characteristics as left bundle branch block VTs with critical areas involving the left ventricular septum. Patients with right ventricular VT breakthrough sites had a lower ejection fraction than did patients without VT breaking out on the right ventricular septum (18% ± 5% vs 33% ± 15%; P = .01). Right ventricular mapping and ablation may be necessary in order to eliminate all inducible VTs in patients with postinfarction VT. More than half the patients with septal myocardial infarction have right ventricular septal areas that are critical for postinfarction VT and that cannot be eliminated by left ventricular ablation alone. Copyright © 2012 Heart Rhythm Society. All rights reserved.

Ventilation patterns mimicking COPD in patients with diaphragmatic pacing for Ondine's curse. [/sup 133/Xe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makhija, M.C.; Bronfman, H.J.; Lange, R.C.

1978-10-01

Ventilation was studied with /sup 133/Xe in 18 patients with central hypoventilation (Ondine's Curse) in whom diaphragmatic pacers were implanted. Three distinct patterns emerged: Type I, improvement in ventilation on the paced side (11 of 18 patients); Type II, improvement on both the paced and unpaced side (4 of 18); and Type III, no improvement (3 of 18). With the pacer off, many of these patients have patterns that mimic chronic obstructive pulmonary disease and that revert to normal with pacing. This retention, clearly reversible, cannot reflect permanent airways or airspace disease.

Influence of Pacing by Periodic Auditory Stimuli on Movement Continuation: Comparison with Self-regulated Periodic Movement

PubMed Central

Ito, Masanori; Kado, Naoki; Suzuki, Toshiaki; Ando, Hiroshi

2013-01-01

[Purpose] The purpose of this study was to investigate the influence of external pacing with periodic auditory stimuli on the control of periodic movement. [Subjects and Methods] Eighteen healthy subjects performed self-paced, synchronization-continuation, and syncopation-continuation tapping. Inter-onset intervals were 1,000, 2,000 and 5,000 ms. The variability of inter-tap intervals was compared between the different pacing conditions and between self-paced tapping and each continuation phase. [Results] There were no significant differences in the mean and standard deviation of the inter-tap interval between pacing conditions. For the 1,000 and 5,000 ms tasks, there were significant differences in the mean inter-tap interval following auditory pacing compared with self-pacing. For the 2,000 ms syncopation condition and 5,000 ms task, there were significant differences from self-pacing in the standard deviation of the inter-tap interval following auditory pacing. [Conclusion] These results suggest that the accuracy of periodic movement with intervals of 1,000 and 5,000 ms can be improved by the use of auditory pacing. However, the consistency of periodic movement is mainly dependent on the inherent skill of the individual; thus, improvement of consistency based on pacing is unlikely. PMID:24259932

A Co-Adaptive Brain-Computer Interface for End Users with Severe Motor Impairment

PubMed Central

Faller, Josef; Scherer, Reinhold; Costa, Ursula; Opisso, Eloy; Medina, Josep; Müller-Putz, Gernot R.

2014-01-01

Co-adaptive training paradigms for event-related desynchronization (ERD) based brain-computer interfaces (BCI) have proven effective for healthy users. As of yet, it is not clear whether co-adaptive training paradigms can also benefit users with severe motor impairment. The primary goal of our paper was to evaluate a novel cue-guided, co-adaptive BCI training paradigm with severely impaired volunteers. The co-adaptive BCI supports a non-control state, which is an important step toward intuitive, self-paced control. A secondary aim was to have the same participants operate a specifically designed self-paced BCI training paradigm based on the auto-calibrated classifier. The co-adaptive BCI analyzed the electroencephalogram from three bipolar derivations (C3, Cz, and C4) online, while the 22 end users alternately performed right hand movement imagery (MI), left hand MI and relax with eyes open (non-control state). After less than five minutes, the BCI auto-calibrated and proceeded to provide visual feedback for the MI task that could be classified better against the non-control state. The BCI continued to regularly recalibrate. In every calibration step, the system performed trial-based outlier rejection and trained a linear discriminant analysis classifier based on one auto-selected logarithmic band-power feature. In 24 minutes of training, the co-adaptive BCI worked significantly (p = 0.01) better than chance for 18 of 22 end users. The self-paced BCI training paradigm worked significantly (p = 0.01) better than chance in 11 of 20 end users. The presented co-adaptive BCI complements existing approaches in that it supports a non-control state, requires very little setup time, requires no BCI expert and works online based on only two electrodes. The preliminary results from the self-paced BCI paradigm compare favorably to previous studies and the collected data will allow to further improve self-paced BCI systems for disabled users. PMID:25014055

New-Onset Left Bundle Branch Block Induced by Transcutaneous Aortic Valve Implantation.

PubMed

Massoullié, Grégoire; Bordachar, Pierre; Ellenbogen, Kenneth A; Souteyrand, Géraud; Jean, Frédéric; Combaret, Nicolas; Vorilhon, Charles; Clerfond, Guillaume; Farhat, Mehdi; Ritter, Philippe; Citron, Bernard; Lusson, Jean-R; Motreff, Pascal; Ploux, Sylvain; Eschalier, Romain

2016-03-01

New-onset left bundle branch block (LBBB) is a specific concern of transcutaneous aortic valve implantation (TAVI) given its estimated incidence ranging from 5% to 65%. This high rate of occurrence is dependent on the type of device used (size and shape), implantation methods, and patient co-morbidities. The appearance of an LBBB after TAVI reflects a very proximal lesion of the left bundle branch as it exits the bundle of His. At times transient, its persistence can lead to permanent pacemaker implantation in 15% to 20% of cases, most often for high-degree atrioventricular block. The management of LBBB after TAVI is currently not defined by international societies resulting in individual centers developing their own management strategy. The potential consequences of LBBB are dysrhythmias (atrioventricular block, syncope, and sudden death) and functional (heart failure) complications. Prompt postprocedural recognition and management (permanent pacemaker implantation) of patients prevents the occurrence of potential complications and may constitute the preferred approach in this frail and elderly population despite additional costs and complications of cardiac pacing. Moreover, the expansion of future indications for TAVI necessitates better identification of the predictive factors for the development of LBBB. Indeed, long-term right ventricular pacing may potentially increase the risk of developing heart failure in this population. In conclusion, it is thus imperative to not only develop new aortic prostheses with a less-deleterious impact on the conduction system but also to prescribe appropriate pacing modes in this frail population. Copyright © 2016 Elsevier Inc. All rights reserved.

Direct His bundle pacing post AVN ablation.

PubMed

Lakshmanadoss, Umashankar; Aggarwal, Ashim; Huang, David T; Daubert, James P; Shah, Abrar

2009-08-01

Atrioventricular nodal (AVN) ablation with concomitant pacemaker implantation is one of the strategies that reduce symptoms in patients with atrial fibrillation (AF). However, the long-term adverse effects of right ventricular (RV) apical pacing have led to the search for alternating sites of pacing. Biventricular pacing produces a significant improvement in functional capacity over RV pacing in patients undergoing AVN ablation. Another alternative site for pacing is direct His bundle to reduce the adverse outcome of RV pacing. Here, we present a case of direct His bundle pacing using steerable lead delivery system in a patient with symptomatic paroxysmal AF with concurrent AVN ablation.

Therapeutic effects of selective atrioventricular node vagal stimulation in atrial fibrillation and heart failure.

PubMed

Zhang, Youhua; Popović, Zoran B; Kusunose, Kenya; Mazgalev, Todor N

2013-01-01

Atrial fibrillation (AF) and heart failure (HF) frequently coexist. We have previously demonstrated that selective atrioventricular node (AVN) vagal stimulation (AVN-VS) can be used to control ventricular rate during AF. Due to withdrawal of vagal activity in HF, the therapeutic effects of AVN-VS may be compromised in the combined condition of AF and HF. Accordingly, this study was designed to evaluate the therapeutic effects of AVN-VS to control ventricular rate in AF and HF. A combined model of AF and HF was created by implanting a dual chamber pacemaker in 24 dogs. A newly designed bipolar electrode was inserted into the ganglionic AVN fat pad and connected to a nerve stimulator for delivering AVN-VS. In all dogs, HF was induced by high rate ventricular pacing at 220 bpm for 4 weeks. AF was then induced and maintained by rapid atrial pacing at 600 bpm after discontinuation of ventricular pacing. These HF + AF dogs were randomized into control (n = 9) and AVN-VS (n = 15) groups. In the latter group, vagal stimulation (310 μs, 20 Hz, 3-7 mA) was delivered continuously for 6 months. Compared with the control, AVN-VS had a consistent effect on ventricular rate slowing (by >50 bpm, all P < 0.001) during the entire 6-month observation period that was associated with left ventricular functional improvement. Moreover, AVN-VS was well tolerated by the treated animals. AVN-VS achieved consistent rate slowing, which was associated with improved ventricular function in a canine AF and HF model. Thus, AVN-VS may be a novel, effective therapeutic option in the combined condition of AF and HF. © 2012 Wiley Periodicals, Inc.

Validation of electromechanical wave imaging in a canine model during pacing and sinus rhythm.

PubMed

Grondin, Julien; Costet, Alexandre; Bunting, Ethan; Gambhir, Alok; Garan, Hasan; Wan, Elaine; Konofagou, Elisa E

2016-11-01

Accurate determination of regional areas of arrhythmic triggers is of key interest to diagnose arrhythmias and optimize their treatment. Electromechanical wave imaging (EWI) is an ultrasound technique that can image the transient deformation in the myocardium after electrical activation and therefore has the potential to detect and characterize location of triggers of arrhythmias. The objectives of this study were to investigate the relationship between the electromechanical and the electrical activation of the left ventricular (LV) endocardial surface during epicardial and endocardial pacing and during sinus rhythm as well as to map the distribution of electromechanical delays. In this study, 6 canines were investigated. Two external electrodes were sutured onto the epicardial surface of the LV. A 64-electrode basket catheter was inserted through the apex of the LV. Ultrasound channel data were acquired at 2000 frames/s during epicardial and endocardial pacing and during sinus rhythm. Electromechanical and electrical activation maps were synchronously obtained from the ultrasound data and the basket catheter, respectively. The mean correlation coefficient between electromechanical and electrical activation was 0.81 for epicardial anterior pacing, 0.79 for epicardial lateral pacing, 0.69 for endocardial pacing, and 0.56 for sinus rhythm. The electromechanical activation sequence determined by EWI follows the electrical activation sequence and more specifically in the case of pacing. This finding is of key interest in the role that EWI can play in the detection of the anatomical source of arrhythmias and the planning of pacing therapies such as cardiovascular resynchronization therapy. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Difference Between Dormant Conduction Sites Revealed by Adenosine Triphosphate Provocation and Unipolar Pace-Capture Sites Along the Ablation Line After Pulmonary Vein Isolation.

PubMed

Kogawa, Rikitake; Okumura, Yasuo; Watanabe, Ichiro; Sonoda, Kazumasa; Sasaki, Naoko; Takahashi, Keiko; Iso, Kazuki; Nagashima, Koichi; Ohkubo, Kimie; Nakai, Toshiko; Kunimoto, Satoshi; Hirayama, Atsushi

2016-01-01

Dormant pulmonary vein (PV) conduction revealed by adenosine/adenosine triphosphate (ATP) provocation test and exit block to the left atrium by pacing from the PV side of the ablation line ("pace and ablate" method) are used to ensure durable pulmonary vein isolation (PVI). However, the mechanistic relation between ATP-provoked PV reconnection and the unexcitable gap along the ablation line is unclear.Forty-five patients with atrial fibrillation (AF) (paroxysmal: 31 patients, persistent: 14 patients; age: 61.1 ± 9.7 years) underwent extensive encircling PVI (EEPVI, 179 PVs). After completion of EEPVI, an ATP provocation test (30 mg, bolus injection) and unipolar pacing (output, 10 mA; pulse width, 2 ms) were performed along the previous EEPVI ablation line to identify excitable gaps. Dormant conduction was revealed in 29 (34 sites) of 179 PVs (16.2%) after EEP-VI (22/45 patients). Pace capture was revealed in 59 (89 sites) of 179 PVs (33.0%) after EEPVI (39/45 patients), and overlapping sites, ie, sites showing both dormant conduction and pace capture, were observed in 22 of 179 (12.3%) PVs (17/45 patients).Some of the ATP-provoked dormant PV reconnection sites were identical to the sites with excitable gaps revealed by pace capture, but most of the PV sites were differently distributed, suggesting that the main underling mechanism differs between these two forms of reconnection. These findings also suggest that performance of the ATP provocation test followed by the "pace and ablate" method can reduce the occurrence of chronic PV reconnections.

Atrial septal pacing in small dogs: a pilot study.

PubMed

Jones, Ashley E; Estrada, Amara H; Pariaut, Romain; Sosa-Samper, Ivan; Shih, Andre C; Mincey, Brandy D; Moïse, N Sydney

2014-09-01

To determine the feasibility of atrial septal pacing via a delivery catheter-guided small non-retracting helix pacing lead. Six healthy beagles (8.3-12.9 kg). Using single plane fluoroscopic guidance, Medtronic(®) 3830 SelectSecure leads were connected to the atrial septum via Medtronic® Attain Select® II standard 90 Left Heart delivery catheter. Pacing threshold and lead impedance were measured at implantation. The Wenckebach point was tested via atrial pacing up to 220 paced pulses per minute (ppm). Thoracic radiographs were performed following implantation to identify the lead position, and repeated at 24 h, 1 month, and 3 months post-operatively. Macro-lead dislodgement occurred in two dogs at 24 h and in three dogs at one-month post-implantation. Lead impedance, measured at the time of implantation, ranged from 583 to 1421 Ω. The Wenckebach point was >220 ppm in four of the six dogs. The remaining two dogs had Wenckebach points of 120 and 190 ppm. This pilot study suggests the selected implantation technique and lead system were inadequate for secure placement in the atrial septum of these dogs. The possible reasons for inadequate stability include unsuitable lead design for this location, inadequate lead slack at the time of implantation and inadequate seating of the lead as evidenced by low impedance at the time of implantation. Other implantation techniques and/or pacing leads should be investigated to determine the optimal way of pacing the atria in small breed dogs that are prone to sinus node dysfunction. Copyright © 2014 Elsevier B.V. All rights reserved.

"U-Pace" Instruction: Improving Student Success by Integrating Content Mastery and Amplified Assistance

ERIC Educational Resources Information Center

Reddy, Diane M.; Pfeiffer, Heidi M.; Fleming, Raymond; Ports, Katie A.; Pedrick, Laura E.; Barnack-Tavlaris, Jessica L.; Jirovec, Danielle L.; Helion, Alicia M.; Swain, Rodney A.

2013-01-01

"U-Pace," an instructional intervention, has potential for widespread implementation because student behavior recorded in any learning management system is used by "U-Pace" instructors to tailor coaching of student learning based on students' strengths and motivations. "U-Pace" utilizes an online learning environment…

[Influence of pacing site on myocardial transmural dispersion of repolarization in intact normal and dilated cardiomyopathy dogs].

PubMed

Bai, Rong; Pu, Jun; Liu, Nian; Lu, Jia-Gao; Zhou, Qiang; Ruan, Yan-Fei; Niu, Hui-Yan; Wang, Lin

2003-12-25

In order to verify the hypothesis that left ventricular epicardial (LV-Epi) pacing and biventricular (BiV) pacing unavoidably influence the myocardial electrophysiological characters and may result in high risk of malignant ventricular arrhythmia, we calculated, in both normal mongrel dogs and dog models with rapid-right-ventricular-pacing induced dilated cardiomyopathy congestive heart failure (DCM-CHF), the monophasic action potential duration (MAPD) and the transmural dispersion of repolarization (TDR) in intracardiac electrogram together with the QT interval and T(peak)-T(end) (T(p(-T(e)) interval in surface electrocardiogram (ECG) during LV-Epi and BiV pacing, compared with those during right ventricular endocardial (RV-Endo) pacing. To prepare the DCM-CHF dog model, rapid right ventricular pacing (250 bpm) was performed for 23.6+/-2.57 days to the dog. All the normal and DCM-CHF dogs were given radio frequency catheter ablation (RFCA) to His bundle with the guide of X-ray fluoroscopy. After the RFCA procedures, the animals were under the situation of complete atrioventricular block so that the canine heart rates could be voluntarily controlled in the following experiments. After a thoracotomy, ECG and monophasic action potentials (MAP) of subendocardial, subepicardial and mid-layer myocardium were recorded synchronously in 8 normal and 5 DCM-CHF dogs during pacing from endocardium of RV apex (RV-Endo), epicardium of LV anterior wall (LV-Epi) and simultaneously both of the above (biventricular, BiV), the later was similar to the ventricular resynchronization therapy to congestive heart failure patients in clinic. The Tp-Te) meant the interval from the peak to the end of T wave, which was a representative index of TDR in surface ECG. The TDR was defined as the difference between the longest and the shortest MAPD of subendocardial, subepicardial and mid-layer myocardium. Our results showed that in normal dogs, pacing participating of LV (LV-Epi, BiV) prolonged MAPD of all the three layers of the myocardium (P<0.05) with the character that mid-layer MAPD was the longest and subepicardial MAPD was the shortest following subendocardial MAPD. At the same time, TDR prolonged from 26.75 ms at RV-Endo pacing to 37.54 ms at BiV pacing and to 47.16 ms at LV-Epi pacing (P<0.001). Meanwhile in surface ECG, BiV and LV-Epi pacing resulted in a longer Tp-Te) interval compared with RV-Endo pacing (P<0.01), without parallel QT interval prolongation. Furthermore, all the DCM-CHF model dogs showed manifestations of congestive heart failure and enlargement of left ventricles. Based on the lengthening of mid-layer MAPD from 257.35 ms to 276.30 ms (P<0.0001) and increase of TDR from 27.58 ms to 33.80 ms (P equals;0.002) in DCM-CHF model due to the structural disorders of myocardium compared with the normal dog, LV-Epi and BiV pacing also led to the effect of prolonging MAPD of three layers of the myocardium and enlarging TDR. From these results we make the conclusions that prolongation of MAPD of subendocardial, subepicardial and mid-layer myocardium and increase in TDR during pacing participating of LV (LV-Epi, BiV) may contribute to the formation of unidirectional block and reentry, which play roles or at least are the high risk factors in the development of malignant ventricular arrhythmia, especially in case of structural disorders of myocardium. These findings must be considered seriously when ventricular resynchronization therapy is performed to congestive heart failure patients.

Vice President Pence Tours Jet Propulsion Laboratory

NASA Image and Video Library

2018-04-28

JPL Director Michael Watkins, left, explains the history of NASA's Jet Propulsion Laboratory and the use of the Mission Support Area to Vice President Mike Pence, seated 4th from left, during a tour of JPL, Saturday, April 28, 2018 in Pasadena, California. Joining the Vice President was, JPL Distinguished Visiting Scientist and Spouse of UAG Chairman James Ellis, Elisabeth Pate-Cornell, left, UAG Chairman, Admiral (Ret) James Ellis, Executive Director of the National Space Council Scott Pace, wife of Mike Pence, Karen Pence, daughter of Mike Pence, Charlotte Pence, and JPL Deputy Director Lt. Gen. (Ret) Larry James. Photo Credit: (NASA/Bill Ingalls)

Japanese Flagship Universities at a Crossroads

ERIC Educational Resources Information Center

Yonezawa, Akiyoshi

2007-01-01

The increasing pace and scope of global structural change has left Japanese flagship universities at a crossroads. Reflecting upon historical trends, current policy changes and respective institutional strategies for global marketing among Japanese top research universities, the author discusses possible future directions for these institutions…

Computational Toxicology in Cancer Risk Assessment

EPA Science Inventory

Risk assessment over the last half century has, for many individual cases served us well, but has proceeded on an extremely slow pace and has left us with considerable uncertainty. There are certainly thousands of compounds and thousands of exposure scenarios that remain unteste...

Evaluation of Left Ventricular Diastolic Dysfunction with Early Systolic Dysfunction Using Two-Dimensional Speckle Tracking Echocardiography in Canine Heart Failure Model.

PubMed

Wu, Wei-Chun; Ma, Hong; Xie, Rong-Ai; Gao, Li-Jian; Tang, Yue; Wang, Hao

2016-04-01

This study evaluated the role of two-dimensional speckle tracking echocardiography (2DSTE) for predicting left ventricular (LV) diastolic dysfunction in pacing-induced canine heart failure. Pacing systems were implanted in 8 adult mongrel dogs, and continuous rapid right ventricular pacing (RVP, 240 beats/min) was maintained for 2 weeks. The obtained measurements from 2DSTE included global strain rate during early diastole (SRe) and during late diastole (SRa) in the longitudinal (L-SRe, L-SRa), circumferential (C-SRe, C-SRa), and radial directions (R-SRe, R-SRa). Changes in heart morphology were observed by light microscopy and transmission electron microscopy at 2 weeks. The onset of LV diastolic dysfunction with early systolic dysfunction occurred 3 days after RVP initiation. Most of the strain rate imaging indices were altered at 1 or 3 days after RVP onset and continued to worsen until heart failure developed. Light and transmission electron microscopy showed myocardial vacuolar degeneration and mitochondrial swelling in the left ventricular at 2 weeks after RVP onset. Pearson's correlation analysis revealed that parameters of conventional echocardiography and 2DSTE showed moderate correlation with LV pressure parameters, including E/Esep' (r = 0.58, P < 0.01), L-SRe (r = -0.58, P < 0.01), E/L-SRe (r = 0.65, P < 0.01), and R-SRe (r = 0.53, P < 0.01). ROC curves analysis showed that these indices of conventional echocardiography and strain rate imaging could effectively predict LV diastolic dysfunction (area under the curve: E/Esep' 0.78; L-SRe 0.84; E/L-SRe 0.80; R-SRe 0.80). 2DSTE was a sensitive and accurate technique that could be used for predicting LV diastolic dysfunction in canine heart failure model. © 2015, Wiley Periodicals, Inc.

Acute effects of febuxostat, a nonpurine selective inhibitor of xanthine oxidase, in pacing induced heart failure.

PubMed

Hou, Mingxiao; Hu, Qingsong; Chen, Yingjie; Zhao, Lin; Zhang, Jianyi; Bache, Robert J

2006-11-01

We investigated whether xanthine oxidase inhibition with febuxostat enhances left ventricular (LV) function and improves myocardial high energy phosphates (HEP) in dogs with pacing-induced heart failure (CHF). Febuxostat (2.2 mg/kg over 10 minutes followed by 0.06 mg/kg/min) caused no change of LV function or myocardial oxygen consumption (MVO2) at rest or during treadmill exercise in normal dogs. In dogs with CHF, febuxostat increased LV dP/dtmax at rest and during heavy exercise (P < 0.05), indicating improved LV function with no change of MVO2. Myocardial adenosine triphosphate (ATP) and phosphocreatine (PCr) were examined using 31P nuclear magnetic resonance spectroscopy in the open chest state. In normal dogs, febuxostat increased PCr/ATP during basal conditions and during high workload produced by dobutamine + dopamine (P < 0.05). PCr/ATP was decreased in animals with CHF; in these animals, febuxostat (given after completing basal and high workload measurements with vehicle) tended to increase PCr/ATP during basal conditions with no effect during catecholamine stimulation. Thus, febuxostat improved LV performance in awake dogs with CHF, but caused only a trend toward increased PCr/ATP in the open chest state. It is possible that the antecedent high workload condition prior to drug administration blunted the effect of febuxostat on HEP in the CHF animals. Alternatively, beneficial effects of febuxostat on LV performance in the failing heart may not involve HEP.

An algorithm for verifying biventricular capture based on evoked-response morphology.

PubMed

Diotallevi, Paolo; Ravazzi, Pier Antonio; Gostoli, Enrico; De Marchi, Giuseppe; Militello, Carmelo; Kraetschmer, Hannes

2005-01-01

Cardiac resynchronization therapy relies on consistent beat-by-beat myocardial capture in both ventricles. A pacemaker ensuring right (RV) and left ventricular (LV) capture through reliable capture verification and automatic output adjustment would contribute to patients' safety and quality of life. We studied the feasibility of an algorithm based on evoked-response (ER) morphology for capture verification in both the ventricles. RV and LV ER signals were recorded in 20 patients (mean age 72.5 years, range 64.3-80.4 years, 4 females and 16 males) during implantation of biventricular (BiV) pacing systems. Leads of several manufacturers were tested. Pacing and intracardiac electrogram (IEGM) recording were performed using an external pulse generator. IEGM and surface-lead electrocardiogram (ECG) signals were recorded under different pacing conditions for 10 seconds each: RV pacing only, LV pacing only, and BiV pacing with several interventricular delays. Based on morphology characteristics, ERs were classified manually for capture and failure to capture, and the validity of the classification was assessed by reference to the ECG. A total of 3,401 LV- and 3,345 RV-paced events were examined. In the RV and LV, the sensitivities of the algorithm were 95.6% and 96.1% in the RV and LV, respectively, and the corresponding specificities were 91.4% and 95.2%, respectively. The lower sensitivity in the RV was attributed to signal blanking in both channels during BiV pacing with a nonzero interventricular delay. The analysis revealed that the algorithm for identifying capture and failure to capture based on the ER-signal morphology was safe and effective in each ventricle with all leads tested in the study.

Optimal pacing modes after cardiac transplantation: is synchronisation of recipient and donor atria beneficial?

PubMed Central

Parry, Gareth; Malbut, Katie; Dark, John H; Bexton, Rodney S

1992-01-01

Objective—To investigate the response of the transplanted heart to different pacing modes and to synchronisation of the recipient and donor atria in terms of cardiac output at rest. Design—Doppler derived cardiac output measurements at three pacing rates (90/min, 110/min and 130/min) in five pacing modes: right ventricular pacing, donor atrial pacing, recipient-donor synchronous pacing, donor atrial-ventricular sequential pacing, and synchronous recipient-donor atrial-ventricular sequential pacing. Patients—11 healthy cardiac transplant recipients with three pairs of epicardial leads inserted at transplantation. Results—Donor atrial pacing (+11% overall) and donor atrial-ventricular sequential pacing (+8% overall) were significantly better than right ventricular pacing (p < 0·001) at all pacing rates. Synchronised pacing of recipient and donor atrial segments did not confer additional benefit in either atrial or atrial-ventricular sequential modes of pacing in terms of cardiac output at rest at these fixed rates. Conclusions—Atrial pacing or atrial-ventricular sequential pacing appear to be appropriate modes in cardiac transplant recipients. Synchronisation of recipient and donor atrial segments in this study produced no additional benefit. Chronotropic competence in these patients may, however, result in improved exercise capacity and deserves further investigation. PMID:1389737

Facing Global Challenges with Materials Innovation

NASA Astrophysics Data System (ADS)

Rizzo, Fernando

2017-10-01

The path of society evolution has long been associated with a growing demand for natural resources and continuous environmental degradation. During the last decades, this pace has accelerated considerably, despite the general concern with the legacy being left for the next generations. Looking ahead, the predicted growth of the world population, and the improvement of life conditions in most regions, point to an increasing demand for energy generation, resulting in additional pressure on the Earth's sustainability. Materials have had a key role in decreasing the use of natural resources, by either improving efficiency of existing technologies or enabling the development of radical new ones. The greenhouse effect (CO2 emissions) and the energy crisis are global challenges that can benefit from the development of new materials for the successful implementation of promising technologies and for the imperative replacement of fossil fuels by renewable sources.

Electromechanical wave imaging of biologically and electrically paced canine hearts in vivo.

PubMed

Costet, Alexandre; Provost, Jean; Gambhir, Alok; Bobkov, Yevgeniy; Danilo, Peter; Boink, Gerard J J; Rosen, Michael R; Konofagou, Elisa E

2014-01-01

Electromechanical wave imaging (EWI) has been show capable of directly and entirely non-invasively mapping the trans mural electromechanical activation in all four cardiac chambers in vivo. In this study, we assessed EWI repeatability and reproducibility, as well as its capability of localizing electronic and, for the first time, biological pacing locations in closed-chest, conscious canines. Electromechanical activation was obtained in six conscious animals during normal sinus rhythm (NSR) and idioventricular rhythms occurring in dogs with complete heart block instrumented with electronic and biologic pacemakers (EPM and BPM respectively). After atrioventricular node ablation, dogs were implanted with an EPM in the right ventricular (RV) endocardial apex (n = 4) and two additionally received a BPM at the left ventricular (LV) epicardial base (n = 2). EWI was performed trans thoracically during NSR, BPM and EPM pacing, in conscious dogs, using an unfocused transmit sequence at 2000 frames/s. During NSR, the EW originated at the right atrium (RA), propagated to the left atrium (LA) and emerged from multiple sources in both ventricles. During EPM, the EW originated at the RV apex and propagated throughout both ventricles. During BPM, the EW originated from the LV basal lateral wall and subsequently propagated throughout the ventricles. EWI differentiated BPM from EPM and NSR and identified the distinct pacing origins. Isochrone comparison indicated that EWI was repeatable and reliable. These findings thus indicate the potential for EWI to serve as a simple, non-invasive and direct imaging technology for mapping and characterizing arrhythmias as well as the treatments thereof. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Vidarabine, an Anti-Herpes Virus Agent, Protects Against the Development of Heart Failure With Relatively Mild Side-Effects on Cardiac Function in a Canine Model of Pacing-Induced Dilated Cardiomyopathy.

PubMed

Nakamura, Takashi; Fujita, Takayuki; Kishimura, Megumi; Suita, Kenji; Hidaka, Yuko; Cai, Wenqian; Umemura, Masanari; Yokoyama, Utako; Uechi, Masami; Ishikawa, Yoshihiro

2016-11-25

In heart failure patients, chronic hyperactivation of sympathetic signaling is known to exacerbate cardiac dysfunction. In this study, the cardioprotective effect of vidarabine, an anti-herpes virus agent, which we identified as a cardiac adenylyl cyclase inhibitor, in dogs with pacing-induced dilated cardiomyopathy (DCM) was evaluated. In addition, the adverse effects of vidarabine on basal cardiac function was compared to those of the β-blocker, carvedilol.Methods and Results:Vidarabine and carvedilol attenuated the development of pacing-induced systolic dysfunction significantly and with equal effectiveness. Both agents also inhibited the development of cardiac apoptosis and fibrosis and reduced the Na + -Ca 2+ exchanger-1 protein level in the heart. Importantly, carvedilol significantly enlarged the left ventricle and atrium; vidarabine, in contrast, did not. Vidarabine-treated dogs maintained cardiac response to β-AR stimulation better than carvedilol-treated dogs did. Vidarabine may protect against pacing-induced DCM with less suppression of basal cardiac function than carvedilol in a dog model. (Circ J 2016; 80: 2496-2505).

Model-based imaging of cardiac electrical function in human atria

NASA Astrophysics Data System (ADS)

Modre, Robert; Tilg, Bernhard; Fischer, Gerald; Hanser, Friedrich; Messnarz, Bernd; Schocke, Michael F. H.; Kremser, Christian; Hintringer, Florian; Roithinger, Franz

2003-05-01

Noninvasive imaging of electrical function in the human atria is attained by the combination of data from electrocardiographic (ECG) mapping and magnetic resonance imaging (MRI). An anatomical computer model of the individual patient is the basis for our computer-aided diagnosis of cardiac arrhythmias. Three patients suffering from Wolff-Parkinson-White syndrome, from paroxymal atrial fibrillation, and from atrial flutter underwent an electrophysiological study. After successful treatment of the cardiac arrhythmia with invasive catheter technique, pacing protocols with stimuli at several anatomical sites (coronary sinus, left and right pulmonary vein, posterior site of the right atrium, right atrial appendage) were performed. Reconstructed activation time (AT) maps were validated with catheter-based electroanatomical data, with invasively determined pacing sites, and with pacing at anatomical markers. The individual complex anatomical model of the atria of each patient in combination with a high-quality mesh optimization enables accurate AT imaging, resulting in a localization error for the estimated pacing sites within 1 cm. Our findings may have implications for imaging of atrial activity in patients with focal arrhythmias.

42 CFR 460.132 - Quality assessment and performance improvement plan.

Code of Federal Regulations, 2011 CFR

2011-10-01

... AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.132 Quality...

42 CFR 460.132 - Quality assessment and performance improvement plan.

Code of Federal Regulations, 2010 CFR

2010-10-01

... AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.132 Quality...

Cardiovascular studies using the chimpanzee (Pan troglodytes)

NASA Technical Reports Server (NTRS)

Hinds, J. E.; Cothran, L. N.; Hawthorne, E. W.

1977-01-01

Despite the phylogenetic similarities between chimpanzees and man, there exists a paucity of reliable data on normal cardiovascular function and the physiological responses of the system to standard interventions. Totally implanted biotelemetry systems or hardwire analog techniques were used to examine the maximum number of cardiovascular variables which could be simultaneously monitored without significantly altering the system's performance. This was performed in order to acquire base-line data not previously obtained in this species, to determine cardiovascular response to specific forcing functions such as ventricular pacing, drug infusions, and lower body negative pressure. A cardiovascular function profile protocol was developed in order to adjust independently the three major factors which modify ventricular performance, namely, left ventricular performance, left ventricular preload, afterload, and contractility. Cardiac pacing at three levels above the ambient rate was used to adjust end diastolic volume (preload). Three concentrations of angiotensin were infused continuously to evaluate afterload in a stepwide fashion. A continuous infusion of dobutamine was administered to raise the manifest contractile state of the heart.

Alternative right ventricular pacing sites.

PubMed

Łuciuk, Dariusz; Łuciuk, Marek; Gajek, Jacek

2015-01-01

The main adverse effect of chronic stimulation is stimulation-induced heart failure in case of ventricular contraction dyssynchrony. Because of this fact, new techniques of stimulation should be considered to optimize electrotherapy. One of these methods is pacing from alternative right ventricular sites. The purpose of this article is to review currently accumulated data about alternative sites of cardiac pacing. Medline and PubMed bases were used to search English and Polish reports published recently. Recent studies report a deleterious effect of long term apical pacing. It is suggested that permanent apical stimulation, by omitting physiological conduction pattern with His-Purkinie network, may lead to electrical and mechanical dyssynchrony of heart muscle contraction. In the long term this pathological situation can lead to severe heart failure and death. Because of this, scientists began to search for some alternative sites of cardiac pacing to reduce the deleterious effect of stimulation. Based on current accumulated data, it is suggested that the right ventricular outflow tract, right ventricular septum, direct His-bundle or biventricular pacing are better alternatives due to more physiological electrical impulse propagation within the heart and the reduction of the dyssynchrony effect. These methods should preserve a better left ventricular function and prevent the development of heart failure in permanent paced patients. As there is still not enough, long-term, randomized, prospective, cross-over and multicenter studies, further research is required to validate the benefits of using this kind of therapy. The article should pay attention to new sites of cardiac stimulation as a better and safer method of treatment.

[Cardiac resynchronization therapy for heart failure - from experimental pacing to evidence-based therapy].

PubMed

Götze, S; Butter, C; Fleck, E

2006-01-01

Within the last decade, cardiac resynchronization therapy (CRT) has become an evidence-based cornerstone for a subset of patients with chronic heart failure. For those, who suffer from ischemic or non-ischemic cardiomyopathies at NYHA III or IV, have sinus rhythm, a left bundle branch block and a left ventricular ejection fraction below 35%, CRT has evolved as an important treatment option with promising results. Numerous studies have shown that in these patients pacemaker-mediated correction of intra- and interventicular conduction disturbances can improve not only clinical symptoms, exercise tolerance and the frequency of hospitalizations, but even more important the overall mortality. These clinical results are due to several functional aspects. In the failing heart characteristic intra- and interventricular alterations in electrical conduction result in mechanical asynchrony that leads to an abnormal contraction of the left ventricle with delayed activation of the lateral wall, a paradoxical septal movement, a reduced diastolic filling and a mitral regurgitation due to dyssynchrony of papillary muscle activation. It is conceivable that these functional changes have fatal consequences for the failing heart. AV-optimized left- or biventricular stimulation by modern pacemakers can correct the pathological dyssynchrony, thereby improving cardiac function and clinical outcome in these patients. Although tremendous progress in cardiac resynchronization therapy has been made during the last decade, a couple of questions still need to be resolved. Critical issues are the identification of patients, who will predictably benefit from CRT, the value of CRT-pacemakers versus CRT-ICDs, and the usefullness of CRT in patients with atrial fibrillation.

42 CFR 460.136 - Internal quality assessment and performance improvement activities.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460...

Wall Thickness, Pulmonary Hypertension, and Diastolic Filling Abnormalities Predict Response to Postoperative Biventricular Pacing

PubMed Central

Brusen, Robin M.; Hahn, Rebecca; Cabreriza, Santos E.; Cheng, Bin; Wang, Daniel Y.; Truong, Wanda; Spotnitz, Henry M.

2017-01-01

Objective Post-cardiopulmonary bypass biventricular pacing improves hemodynamics but without clearly defined predictors of response. Based on preclinical studies and prior observations, it was suspected that diastolic dysfunction or pulmonary hypertension is predictive of hemodynamic benefit. Design Randomized controlled study of temporary biventricular pacing after cardiopulmonary bypass. Setting Single-center study at university-affiliated tertiary care hospital. Interventions Patients who underwent bypass with pre-operative ejection fraction ≤40% and QRS duration ≥100 ms or double-valve surgery were enrolled. At 3 time points between separation from bypass and postoperative day 1, pacing delays were varied to optimize hemodynamics. Participants Data from 43 patients were analyzed. Measurements and Main Results Cardiac output and arterial pressure were measured under no pacing, atrial pacing, and biventricular pacing. Preoperative echocardiograms and pulmonary artery catheterizations were reviewed, and measures of both systolic and diastolic function were compared to hemodynamic response. Early after separation, improvement in cardiac output was positively correlated with pulmonary vascular resistance (R2 = 0.97, p < 0.001), ventricle wall thickness (R2 = 0.72, p = 0.002)), and E/e′, a measure of abnormal diastolic ventricular filling velocity (R2 = 0.56, p = 0.04). Similar trends were seen with mean arterial pressure. QRS duration and ejection fraction did not correlate significantly with improvements in hemodynamics. Conclusions There may be an effect of biventricular pacing related to amelioration of abnormal diastolic filling patterns rather than electrical resynchronization in the postoperative state. PMID:25998068

Can body surface microvolt T-wave alternans distinguish concordant and discordant intracardiac alternans?

PubMed

Floré, Vincent; Claus, Piet; Symons, Rolf; Smith, Godfrey L; Sipido, Karin R; Willems, Rik

2013-08-01

There is convincing experimental evidence that cellular action potential duration (APD) alternans is arrhythmogenic but its relationship with body surface microvolt T-wave alternans (MTWA) remains unclear. We investigated the relationship between MTWA and APD alternans induced by alternating cycle length (CL) pacing in a pig model. In 10 pigs, catheters in the right atrium (RA) and right (RV) and left ventricle (LV) allowed pacing and recording of monophasic action potentials (MAP). During RA pacing at stable 500-ms CL, LV was paced at alternating CL (505 ms and 495 ms). Changing the alternating LV (A-LV) pacing delay changes the size of the region with alternating ventricular activation. Spectral analysis of intracardiac MAP was correlated with body surface MTWA. In a similar setup (during alternating pacing in RV and LV), we investigated concordant versus discordant APD alternans. Pacing the LV with subtle alternating cycle lengths at short A-LV delay leads to broad QRS (97 ± 10 ms), body surface MTWA (mean Valt 4.2 ± 1.8 µV), and positive RR-interval alternans. At longer A-LV delay, not resulting in QRS widening (68 ± 5 ms), body surface RR alternans was absent but MTWA remained detectable and was even more pronounced (8.7 ± 5.1 µV, P < 0.01). During both concordant and discordant pacing MTWA was present. The precordial leads were better for detecting discordant APD alternans (8.0 ± 2.9 µV and 12.8 ± 4.52 µV, P = 0.02). MTWA is a potent technique to detect subtle and isolated intracardiac APD alternans that is artificially induced by alternating pacing. In the same model, discordant activation alternans can only be discriminated from concordant when using a quantifying approach of MTWA analysis. ©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.

Externalized Conductor Cables in QuickSite Left Ventricular Pacing Lead and Riata Right Ventricular Lead in a Single Patient: A Common Problem With Silicone Insulation

PubMed Central

Lakshmanadoss, Umashankar; Hackett, Vera; Deshmukh, Pramod

2012-01-01

QuickSite (St Jude Medical, Sylmar, CA, USA) is a silicone and polyurethane-insulated coronary sinus pacing lead. Riata lead (St Jude Medical, Sylmar, CA, USA) is a silicone insulated right ventricular shock lead. Recently, insulation breach of silicone based leads raised a huge concern. Fluoroscopic examination of these two leads in the same patient revealed externalization of these two leads. Same mechanism producing insulation breach of Riata lead may be involved in externalization of QuickSite LV lead as distal part of insulation is also made of silicone. PMID:28348692

Earlier Right Ventricular Pacing in Cardiac Resynchronization Therapy for a Patient with Right Axis Deviation.

PubMed

Hattori, Yusuke; Ishibashi, Kohei; Noda, Takashi; Okamura, Hideo; Kanzaki, Hideaki; Anzai, Toshihisa; Yasuda, Satoshi; Kusano, Kengo

2017-09-01

We describe the case of a 37-year-old woman who presented with complete right bundle branch block and right axis deviation. She was admitted to our hospital due to severe heart failure and was dependent on inotropic agents. Cardiac resynchronization therapy was initiated but did not improve her condition. After the optimization of the pacing timing, we performed earlier right ventricular pacing, which led to an improvement of her heart failure. Earlier right ventricular pacing should be considered in patients with complete right bundle branch block and right axis deviation when cardiac resynchronization therapy is not effective.

Empiric versus imaging guided left ventricular lead placement in cardiac resynchronization therapy (ImagingCRT): study protocol for a randomized controlled trial.

PubMed

Sommer, Anders; Kronborg, Mads Brix; Poulsen, Steen Hvitfeldt; Böttcher, Morten; Nørgaard, Bjarne Linde; Bouchelouche, Kirsten; Mortensen, Peter Thomas; Gerdes, Christian; Nielsen, Jens Cosedis

2013-04-26

Cardiac resynchronization therapy (CRT) is an established treatment in heart failure patients. However, a large proportion of patients remain nonresponsive to this pacing strategy. Left ventricular (LV) lead position is one of the main determinants of response to CRT. This study aims to clarify whether multimodality imaging guided LV lead placement improves clinical outcome after CRT. The ImagingCRT study is a prospective, randomized, patient- and assessor-blinded, two-armed trial. The study is designed to investigate the effect of imaging guided left ventricular lead positioning on a clinical composite primary endpoint comprising all-cause mortality, hospitalization for heart failure, or unchanged or worsened functional capacity (no improvement in New York Heart Association class and <10% improvement in six-minute-walk test). Imaging guided LV lead positioning is targeted to the latest activated non-scarred myocardial region by speckle tracking echocardiography, single-photon emission computed tomography, and cardiac computed tomography. Secondary endpoints include changes in LV dimensions, ejection fraction and dyssynchrony. A total of 192 patients are included in the study. Despite tremendous advances in knowledge with CRT, the proportion of patients not responding to this treatment has remained stable since the introduction of CRT. ImagingCRT is a prospective, randomized study assessing the clinical and echocardiographic effect of multimodality imaging guided LV lead placement in CRT. The results are expected to make an important contribution in the pursuit of increasing response rate to CRT. Clinicaltrials.gov identifier NCT01323686. The trial was registered March 25, 2011 and the first study subject was randomized April 11, 2011.

Language and Memory Improvements following tDCS of Left Lateral Prefrontal Cortex.

PubMed

Hussey, Erika K; Ward, Nathan; Christianson, Kiel; Kramer, Arthur F

2015-01-01

Recent research demonstrates that performance on executive-control measures can be enhanced through brain stimulation of lateral prefrontal regions. Separate psycholinguistic work emphasizes the importance of left lateral prefrontal cortex executive-control resources during sentence processing, especially when readers must override early, incorrect interpretations when faced with temporary ambiguity. Using transcranial direct current stimulation, we tested whether stimulation of left lateral prefrontal cortex had discriminate effects on language and memory conditions that rely on executive-control (versus cases with minimal executive-control demands, even in the face of task difficulty). Participants were randomly assigned to receive Anodal, Cathodal, or Sham stimulation of left lateral prefrontal cortex while they (1) processed ambiguous and unambiguous sentences in a word-by-word self-paced reading task and (2) performed an n-back memory task that, on some trials, contained interference lure items reputed to require executive-control. Across both tasks, we parametrically manipulated executive-control demands and task difficulty. Our results revealed that the Anodal group outperformed the remaining groups on (1) the sentence processing conditions requiring executive-control, and (2) only the most complex n-back conditions, regardless of executive-control demands. Together, these findings add to the mounting evidence for the selective causal role of left lateral prefrontal cortex for executive-control tasks in the language domain. Moreover, we provide the first evidence suggesting that brain stimulation is a promising method to mitigate processing demands encountered during online sentence processing.

Language and Memory Improvements following tDCS of Left Lateral Prefrontal Cortex

PubMed Central

Hussey, Erika K.; Ward, Nathan; Christianson, Kiel; Kramer, Arthur F.

2015-01-01

Recent research demonstrates that performance on executive-control measures can be enhanced through brain stimulation of lateral prefrontal regions. Separate psycholinguistic work emphasizes the importance of left lateral prefrontal cortex executive-control resources during sentence processing, especially when readers must override early, incorrect interpretations when faced with temporary ambiguity. Using transcranial direct current stimulation, we tested whether stimulation of left lateral prefrontal cortex had discriminate effects on language and memory conditions that rely on executive-control (versus cases with minimal executive-control demands, even in the face of task difficulty). Participants were randomly assigned to receive Anodal, Cathodal, or Sham stimulation of left lateral prefrontal cortex while they (1) processed ambiguous and unambiguous sentences in a word-by-word self-paced reading task and (2) performed an n-back memory task that, on some trials, contained interference lure items reputed to require executive-control. Across both tasks, we parametrically manipulated executive-control demands and task difficulty. Our results revealed that the Anodal group outperformed the remaining groups on (1) the sentence processing conditions requiring executive-control, and (2) only the most complex n-back conditions, regardless of executive-control demands. Together, these findings add to the mounting evidence for the selective causal role of left lateral prefrontal cortex for executive-control tasks in the language domain. Moreover, we provide the first evidence suggesting that brain stimulation is a promising method to mitigate processing demands encountered during online sentence processing. PMID:26528814

77 FR 3958 - Mortgage Assets Affected by PACE Programs

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-26

... of home improvement projects (e.g., home insulation, solar panels, geothermal energy units, etc... (``ANPR'') concerning mortgage assets affected by Property Assessed Clean Energy (``PACE'') programs and... February 28, 2011, that deal with property assessed clean energy (PACE) programs.'' In response to and...

On the Effectiveness of a Neural Network for Adaptive External Pacing.

ERIC Educational Resources Information Center

Montazemi, Ali R.; Wang, Feng

1995-01-01

Proposes a neural network model for an intelligent tutoring system featuring adaptive external control of student pacing. An experiment was conducted, and students using adaptive external pacing experienced improved mastery learning and increased motivation for time management. Contains 66 references. (JKP)

Hemispheric Asymmetries in the Activation and Monitoring of Memory Errors

ERIC Educational Resources Information Center

Giammattei, Jeannette; Arndt, Jason

2012-01-01

Previous research on the lateralization of memory errors suggests that the right hemisphere's tendency to produce more memory errors than the left hemisphere reflects hemispheric differences in semantic activation. However, all prior research that has examined the lateralization of memory errors has used self-paced recognition judgments. Because…

Operate to Know: An Operational and Intelligence for the Operational Level of War

DTIC Science & Technology

2014-06-13

hazardous about this form of German warfare that became visible over time. 12 As exhilarating as fast-paced shock maneuver was, it left behind...significant uncertainty into his view of Allied intentions. After Dieppe, Hitler moved eight additional divisions into France to beef up the Western

The Swedish Superintendent in the Policy Stream

ERIC Educational Resources Information Center

Johansson, Olof; Nihlfors, Elisabet

2014-01-01

During the last several decades, educational reform in Sweden has been at once contentious, fast paced, and uneven as control of Parliament and educational policy shifted between left- and right-wing political factions. These political power shifts within Parliament created tension between national and local municipal governments and provoked…

Non-selective His bundle pacing with a biphasic waveform: enhancing septal resynchronization.

PubMed

Ortega, Daniel F; Barja, Luis D; Logarzo, Emilio; Mangani, Nicolas; Paolucci, Analia; Bonomini, Maria P

2018-05-01

His bundle pacing has shown to prevent detrimental effects from right ventricular apical pacing (RVA) and proved to resynchronize many conduction disturbances cases. However, the extent of His bundle pacing resynchronization is limited. An optimized stimulation waveform could expand this limit when implemented in His bundle pacing sets. In this work, we temporarily implemented RVA and Non-selective His bundle pacing with a biphasic anodal-first waveform (AF-nHB) and compared their effects against sinus rhythm (SR). Fifteen patients referred for electrophysiologic study with conduction disturbances, cardiomyopathy and ejection fraction below 35% were enrolled for the study. The following acute parameters were measured: QRS duration, left ventricular activation (RLVT), time of isovolumic contraction (IVCT), ejection fraction (EF), and dP/dtmax. QRS duration and RLVT decreased markedly under AF-nHB (SR: 169 ± 34 ms vs. nHB: 116 ± 31 ms, P < 0.0005) while RVA significantly increased QRS duration (SR: 169 ms vs. RVA: 198 ms, P < 0.05) and did not change RLVT (P = NS). Consistently, IVCT moderately decreased under AF-nHB (SR: 238 ms vs. RVA: 184 ms, P < 0.05 vs. SR) and dP/dtmax showed a 93.35 [mmHg] average increase under AF-nHB against SR. Also, T-wave inversions were observed during AF-nHB immediately after SR and RVA pacing suggesting the occurrence of cardiac memory. AF-nHB corrected bundle branch blocks in patients with severe conduction disturbances, even in those with dilated cardiomiopathy, outstanding from RVA. Also, the occurrence of cardiac memory during AF-nHB turned up as an observational finding of this study.

An evaluation of the use of new Doppler methods for detecting longitudinal function abnormalities in a pacing-induced heart failure model

NASA Technical Reports Server (NTRS)

Tabata, Tomotsugu; Cardon, Lisa A.; Armstrong, Guy P.; Fukamach, Kiyotaka; Takagaki, Masami; Ochiai, Yoshie; McCarthy, Patrick M.; Thomas, James D.

2003-01-01

BACKGROUND: Doppler tissue echocardiography and color M-mode Doppler flow propagation velocity have proven useful in evaluating cross-sections of patients with left ventricular (LV) dysfunction, but experience with serial changes is limited. Purpose and methods: We tested their use by evaluating the temporal changes of LV function in a pacing-induced congestive heart failure model. Rapid ventricular pacing was initiated and maintained in 20 dogs for 4 weeks. Echocardiography was performed at baseline and weekly during brief pacing cessation. RESULTS: With rapid pacing, LV volume significantly increased and ejection fraction (57%-28%), stroke volume (37-18 mL), and mitral annulus systolic velocity (16.1-6.6 cm/s) by Doppler tissue echocardiography significantly decreased, with ejection fraction and mitral annulus systolic velocity closely correlated (r = 0.706, P <.0001). In contrast to the mitral inflow velocities, mitral annulus early diastolic velocity decreased steadily (12.3-7.3 cm/s) resulting in a dramatic decrease in mitral annulus early/late (1.22-0.57) diastolic velocity with no tendency toward pseudonormalization. The color M-mode Doppler flow propagation velocity also showed significant steady decrease (57-24 cm/s) throughout the pacing period. Multiple regression analysis chose mitral annulus systolic velocity (r = 0.895, P <.0001) and propagation velocity (r = 0.782, P <.0001) for the most important factor predicting LV systolic and diastolic function, respectively. CONCLUSIONS: Doppler tissue echocardiography and color M-mode Doppler flow could evaluate the serial deterioration in LV dysfunction throughout the pacing period. These were more useful in quantifying progressive LV dysfunction than conventional ehocardiographic techniques, and were probably relatively independent of preload. These techniques could be suitable for longitudinal evaluation in addition to the cross-sectional study.

Atrial Fibrillation Pacing Decreases Intravascular Shear Stress in a New Zealand White Rabbit Model: Implications in Endothelial Function

PubMed Central

Jen, Nelson; Yu, Fei; Lee, Juhyun; Wasmund, Steve; Dai, Xiaohu; Chen, Christina; Chawareeyawong, Pai; Yang, Yongmo; Li, Rongsong; Hamdan, Mohamed H.; Hsiai, Tzung

2012-01-01

Atrial fibrillation (AF) is characterized by multiple rapid and irregular atrial depolarization leading to rapid ventricular responses exceeding 100 beats per minute (bpm). We hypothesized that rapid and irregular pacing reduced intravascular shear stress (ISS) with implication to modulating endothelial responses. To simulate AF, we paced the left atrial appendage of New Zealand White (NZW) rabbits (n=4) at rapid and irregular intervals. Surface electrical cardiograms (ECG) were recorded for atrial and ventricular rhythm, and intravascular convective heat transfer was measured by micro thermal sensors, from which ISS was inferred. Rapid and irregular pacing decreased arterial systolic and diastolic pressures (baseline: 99/75 mmHg; rapid regular pacing: 92/73; rapid irregular pacing: 90/68; P < 0.001, n=4), temporal gradients (∂τ/∂t from 1275 ± 80 to 1056 ± 180 dyne/cm2·s), and reduced ISS (from baseline at 32.0 ± 2.4 to 22.7 ± 3.5 dyne/cm2). Computational fluid dynamics (CFD) code demonstrated that experimentally inferred ISS provided a close approximation to the computed wall shear stress (WSS) at a given catheter to vessel diameter ratio, shear stress range, and catheter position. In an in vitro flow system in which time-averaged shear stress was maintained at τavg=23 ±4 dyn·cm−2·s−1, we further demonstrated that rapid pulse rates at 150 bpm down-regulated endothelial nitric oxide (NO), promoted superoxide (O2·−) production, and increased monocyte binding to endothelial cells. These findings suggest that rapid pacing reduces ISS and ∂τ/∂t, and rapid pulse rates modulate endothelial responses. PMID:22983703

Electrophysiological determinants of arrhythmic susceptibility upon endocardial and epicardial pacing in guinea-pig heart.

PubMed

Osadchii, O E

2012-08-01

Endocardial pacing instituted to treat symptomatic bradycardia may nevertheless promote tachyarrhythmia in some pacemaker-implanted patients. We sought to determine the contributing electrophysiological mechanisms. Left ventricular (LV) monophasic action potential duration (APD(90)) and effective refractory periods were determined in perfused guinea-pig hearts along with volume-conducted ECG recordings during epicardial and endocardial stimulations. Consistent with electrotonic modulation of repolarization, APD(90) at a given (either epicardial or endocardial) recording site tended to be longer while pacing from the ipsilateral LV site as compared to stimulations applied at the opposite side of ventricular wall. As a result, the intrinsic transmural repolarization gradient was amplified during endocardial pacing while being significantly reduced upon epicardial stimulations. The maximum slope of APD(90) restitution was greater upon endocardial than epicardial pacing. The excitability was found to recur at earlier repolarization time point at endocardium than epicardium, thereby contributing to increased endocardial critical intervals for re-excitation. Premature extrasystolic beats could have been elicited at shorter coupling stimulation intervals and propagated with greater transmural conduction delay upon endocardial than epicardial stimulations. Endocardial site exhibited lower ventricular fibrillation thresholds and greater inducibility of tachyarrhythmia upon extrasystolic stimulations as compared to epicardium. Arrhythmic susceptibility in guinea-pig heart is greater during endocardial than epicardial pacing because of greater transmural APD(90) dispersion, steeper electrical restitution slopes, greater critical intervals for LV re-excitation and slower transmural conduction of the earliest premature ectopic beats. Further studies are warranted to determine whether these effects may contribute to proarrhythmia in paced human patients. © 2012 The Author Acta Physiologica © 2012 Scandinavian Physiological Society.

Additional electrodes on the Quartet™ LV lead provide more programmable pacing options than bipolar and tripolar equivalents.

PubMed

O'Donnell, David; Sperzel, Johannes; Thibault, Bernard; Rinaldi, Christopher A; Pappone, Carlo; Gutleben, Klaus-Jürgen; Leclercq, Christopher; Razavi, Hedi; Ryu, Kyungmoo; Mcspadden, Luke C; Fischer, Avi; Tomassoni, Gery

2017-04-01

The aim of this study was to evaluate any benefits to the number of viable pacing vectors and maximal spatial coverage with quadripolar left ventricular (LV) leads when compared with tripolar and bipolar equivalents in patients receiving cardiac resynchronization therapy (CRT). A meta-analysis of five previously published clinical trials involving the Quartet™ LV lead (St Jude Medical, St Paul, MN, USA) was performed to evaluate the number of viable pacing vectors defined as capture thresholds ≤2.5 V and no phrenic nerve stimulation and maximal spatial coverage of viable vectors in CRT patients at pre-discharge (n = 370) and first follow-up (n = 355). Bipolar and tripolar lead configurations were modelled by systematic elimination of two and one electrode(s), respectively, from the Quartet lead. The Quartet lead with its four pacing electrodes exhibited the greatest number of pacing vectors per patient when compared with the best bipolar and the best tripolar modelled equivalents. Similarly, the Quartet lead provided the highest spatial coverage in terms of the distance between two furthest viable pacing cathodes when compared with the best bipolar and the best tripolar configurations (P < 0.05). Among the three modelled bipolar configurations, the lead configuration with the two most distal electrodes resulted in the highest number of viable pacing vectors. Among the four modelled tripolar configurations, elimination of the second proximal electrode (M3) resulted in the highest number of viable pacing options per patient. There were no significant differences observed between pre-discharge and first follow-up analyses. The Quartet lead with its four electrodes and the capability to pace from four anatomical locations provided the highest number of viable pacing vectors at pre-discharge and first follow-up visits, providing more flexibility in device programming and enabling continuation of CRT in more patients when compared with bipolar and tripolar equivalents. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Minimal invasive epicardial lead implantation: optimizing cardiac resynchronization with a new mapping device for epicardial lead placement.

PubMed

Maessen, J G; Phelps, B; Dekker, A L A J; Dijkman, B

2004-05-01

To optimize resynchronization in biventricular pacing with epicardial leads, mapping to determine the best pacing site, is a prerequisite. A port access surgical mapping technique was developed that allowed multiple pace site selection and reproducible lead evaluation and implantation. Pressure-volume loops analysis was used for real time guidance in targeting epicardial lead placement. Even the smallest changes in lead position revealed significantly different functional results. Optimizing the pacing site with this technique allowed functional improvement up to 40% versus random pace site selection.

Translational validity of PASAT and the effect of fatigue and mood in patients with relapsing remitting MS: A functional MRI study.

PubMed

Iancheva, Dessislava; Trenova, Anastasiya G; Terziyski, Kiril; Kandilarova, Sevdalina; Mantarova, Stefka

2018-04-03

Paced Auditory Serial Addition Test (PASAT) is used for assessment of information processing speed, attention, and working memory, which are the most frequently affected cognitive domains in multiple sclerosis (MS) patients, and may be significantly affected by fatigue. However, the effect of fatigue and mood on the PASAT performance in MS patients translationally validated by fMRI has not been studied yet. The aim of this study is to investigate the translational validity of the PASAT, using fMRI during a paced visual serial addition test (PVSAT) paradigm in patients with relapsing remitting MS (RRMS) and to assess the impact of fatigue and mood on test performance. Fourteen patients with RRMS in remission and 14 healthy controls, matched by sex, age, and educational status, were enrolled in the study. The subjects underwent a standard neurological examination, neuropsychological evaluation with the PASAT 3', fMRI scanning with a PVSAT paradigm, and Beck Depression Inventory. All patients were assessed by the Modified Fatigue Impact Scale. Paced Auditory Serial Addition Test score was lower in patients (41.4 ± 15.5 vs 51.6 ± 7.5, P = .035). A moderate negative correlation (P = -0.563, P = 0.036) was found between PASAT and MIFS scores. The fMRI scanning showed significant activations in several clusters that differed between patients and controls. The patient group presented wider cluster activation; Brodmann area (BA) 6-bilaterally; left BA7, 8, and 9; and right BA40, while controls presented with activations in left BA6 and BA44. Significant negative correlations between PASAT score and cortical activations in left BA23, right BA32, and left BA7 were observed in patients only. Our results show that poorer performance on the PASAT is associated with higher activation in areas connected with working memory, attention, and emotional processes during the fMRI assessment with PVSAT paradigm, which provides evidence for the translational validity of the PASAT in patients with RRMS. © 2018 John Wiley & Sons, Ltd.

Imaging the Propagation of the Electromechanical Wave in Heart Failure Patients with Cardiac Resynchronization Therapy.

PubMed

Bunting, Ethan; Lambrakos, Litsa; Kemper, Paul; Whang, William; Garan, Hasan; Konofagou, Elisa

2017-01-01

Current electrocardiographic and echocardiographic measurements in heart failure (HF) do not take into account the complex interplay between electrical activation and local wall motion. The utilization of novel technologies to better characterize cardiac electromechanical behavior may lead to improved response rates with cardiac resynchronization therapy (CRT). Electromechanical wave imaging (EWI) is a noninvasive ultrasound-based technique that uses the transient deformations of the myocardium to track the intrinsic EW that precedes myocardial contraction. In this paper, we investigate the performance and reproducibility of EWI in the assessment of HF patients and CRT. EWI acquisitions were obtained in five healthy controls and 16 HF patients with and without CRT pacing. Responders (n = 8) and nonresponders (n = 8) to CRT were identified retrospectively on the basis of left ventricular (LV) reverse remodeling. Electromechanical activation maps were obtained in all patients and used to compute a quantitative parameter describing the mean LV lateral wall activation time (LWAT). Mean LWAT was increased by 52.1 ms in HF patients in native rhythm compared to controls (P < 0.01). For all HF patients, CRT pacing initiated a different electromechanical activation sequence. Responders exhibited a 56.4-ms ± 28.9-ms reduction in LWAT with CRT pacing (P < 0.01), while nonresponders showed no significant change. In this initial feasibility study, EWI was capable of characterizing local cardiac electromechanical behavior as it pertains to HF and CRT response. Activation sequences obtained with EWI allow for quantification of LV lateral wall electromechanical activation, thus providing a novel method for CRT assessment. © 2016 Wiley Periodicals, Inc.

[Analysis of pacemaker ECGs].

PubMed

Israel, Carsten W; Ekosso-Ejangue, Lucy; Sheta, Mohamed-Karim

2015-09-01

The key to a successful analysis of a pacemaker electrocardiogram (ECG) is the application of the systematic approach used for any other ECG without a pacemaker: analysis of (1) basic rhythm and rate, (2) QRS axis, (3) PQ, QRS and QT intervals, (4) morphology of P waves, QRS, ST segments and T(U) waves and (5) the presence of arrhythmias. If only the most obvious abnormality of a pacemaker ECG is considered, wrong conclusions can easily be drawn. If a systematic approach is skipped it may be overlooked that e.g. atrial pacing is ineffective, the left ventricle is paced instead of the right ventricle, pacing competes with intrinsic conduction or that the atrioventricular (AV) conduction time is programmed too long. Apart from this analysis, a pacemaker ECG which is not clear should be checked for the presence of arrhythmias (e.g. atrial fibrillation, atrial flutter, junctional escape rhythm and endless loop tachycardia), pacemaker malfunction (e.g. atrial or ventricular undersensing or oversensing, atrial or ventricular loss of capture) and activity of specific pacing algorithms, such as automatic mode switching, rate adaptation, AV delay modifying algorithms, reaction to premature ventricular contractions (PVC), safety window pacing, hysteresis and noise mode. A systematic analysis of the pacemaker ECG almost always allows a probable diagnosis of arrhythmias and malfunctions to be made, which can be confirmed by pacemaker control and can often be corrected at the touch of the right button to the patient's benefit.

The roles of the Q (q) wave in lead I and QRS frontal axis for diagnosing loss of left ventricular capture during cardiac resynchronization therapy.

PubMed

Cao, Yuan-Yuan; Su, Yan-Gang; Bai, Jin; Wang, Wei; Wang, Jing-Feng; Qin, Sheng-Mei; Ge, Jun-Bo

2015-01-01

Loss of left ventricular (LV) capture may lead to deterioration of heart failure in patients with cardiac resynchronization therapy (CRT). Recognition of loss of LV capture in time is important in clinical practice. A total of 422 electrocardiograms were acquired and analyzed from 53 CRT patients at 8 different pacing settings (LV only, right ventricle [RV] only, biventricular [BV] pacing with LV preactivation of 60, 40, 20, and 0 milliseconds and RV preactivation of 20 and 40 milliseconds). A modified Ammann algorithm by adding a third step-presence of Q (q, or QS) wave-to the original 2-step Ammann algorithm and a QRS axis shift method were devised to identify the loss of LV capture. The accuracy of modified Ammann algorithm was significantly higher than that of Ammann algorithm (78.9% vs. 69.1%, P < 0.001). The accuracy of the axis shift method was 66.4%, which was significantly lower than the modified Ammann algorithm (P < 0.001) and similar to the original one (P = 0.412). However, in the ECGs with QRS axis shift, 96.8% were correctly classified. LV preactivation or simultaneous BV activation and LV lead positioned in nonposterior or noninferior wall could elevate the accuracies of the modified Ammann algorithm and the QRS axis shift method. The accuracy of the modified Ammann algorithm is greatly improved. The QRS axis shift method can help diagnose LV capture. The LV preactivation, or simultaneous BV activation and LV lead positioned in nonposterior or noninferior wall can increase the diagnostic power of the modified Ammann algorithm and QRS axis shift method. © 2014 Wiley Periodicals, Inc.

A feasible approach for direct his-bundle pacing using a new steerable catheter to facilitate precise lead placement.

PubMed

Zanon, Francesco; Baracca, Enrico; Aggio, Silvio; Pastore, Gianni; Boaretto, Graziano; Cardano, Paola; Marotta, Tiziana; Rigatelli, Gianluca; Galasso, Mariapaola; Carraro, Mauro; Zonzin, Pietro

2006-01-01

Much clinical evidence has shown that right ventricular (RV) apical pacing is detrimental to left ventricular function. Preservation of the use of the His-Purkinje (H-P) system may be ideal in heart block that is restricted to the AV node, but may be of no benefit when H-P disease exists. To investigate the feasibility of direct His-bundle pacing (DHBP) using a new system consisting of a steerable catheter and a new 4.1 F screw-in lead. Between May and December 2004, 26 patients (19 male, mean age: 77 +/- 5 years) with a standard pacemaker (PM) indication and preserved His-bundle conduction were enrolled and DHBP was attempted. DHBP was achieved in 24 patients (92%); two patients were paced in the His area, but the paced QRS morphology and duration were different from the native QRS. The mean time for lead positioning was 19 +/- 17 minutes, the mean fluoroscopy time was 11 +/- 8 minutes, and the total procedure time (skin-to-skin including positioning of a quadripolar diagnostic catheter for His recording) was 75 +/- 18 minutes. In DHBP pacing, the acute pacing threshold was 2.3 +/- 1.0 V at a pulse duration of 0.5 msec, and the sensed potentials were 2.9 +/- 2.0 mV. At a 3-month follow-up examination, the same QRS duration and morphology recorded on implantation were observed in all patients. The pacing threshold was 2.8 +/- 1.4 V, and sensed potentials were 2.5 +/- 1.8 mV; the sensing configuration was changed from bipolar to unipolar in 6 patients to resolve undersensing issues. No major complications were observed. This feasibility study shows that DHBP can be accomplished with a new system consisting of a steerable catheter and an active fixation lead in 92% of the patients in whom it was attempted.

Electromechanical Wave Imaging of biologically and electrically paced canine hearts in vivo

PubMed Central

Costet, Alexandre; Provost, Jean; Gambhir, Alok; Bobkov, Yevgeniy; Danilo, Peter; Boink, Gerard J.J.; Rosen, Michael R.; Konofagou, Elisa

2014-01-01

Ultrasound-based, Electromechanical Wave (EW) Imaging (EWI) can directly and entirely noninvasively map the transmural electromechanical activation in all four cardiac chambers in vivo. In this study, we assessed EWI repeatability and reproducibility, as well as its capability in localizing electronic and, for the first time, biological pacemakers in closed-chest, conscious canines. Electromechanical activation was obtained in six conscious animals during normal sinus rhythm (NSR), and idioventricular rhythms occurring in dogs in heart block instrumented with electronic and biological pacemakers (EPM and BPM respectively). After AV node ablation, dogs were implanted with an EPM in the right ventricular (RV) endocardial apex (n=4) and two additionally received a BPM at the left ventricular (LV) epicardial base (n=2). EWI was performed transthoracically during NSR, BPM, and EPM pacing, in conscious dogs, using an unfocused transmit sequence at 2000 frames/second. During NSR, the EW originated at the right atrium (RA), propagated to the left atrium (LA) and emerged from multiple sources in both ventricles. During EPM, the EW originated at the RV apex and propagated throughout both ventricles. During BPM, the EW originated from the LV basal lateral wall and subsequently propagated throughout the ventricles. EWI differentiated BPM from EPM and NSR and identified the distinct pacing origins. Isochrone comparison demonstrated that EWI was repeatable and reliable. These findings thus indicate the EWI potential to serve as a simple, noninvasive and direct imaging technology for mapping and characterizing arrhythmias as well as the treatments thereof. PMID:24239363

Using Surveys of Students' Social-Emotional Learning and School Climate for Accountability and Continuous Improvement

ERIC Educational Resources Information Center

Hough, Heather; Kalogrides, Demetra; Loeb, Susanna

2017-01-01

The research featured in this paper is part of the CORE-PACE Research Partnership, through which Policy Analysis for California Education (PACE) has partnered with the CORE districts to conduct research designed to support them in continuous improvement while simultaneously helping to improve policy and practice in California and nationwide.…

The downside of downtime: The prevalence and work pacing consequences of idle time at work.

PubMed

Brodsky, Andrew; Amabile, Teresa M

2018-05-01

Although both media commentary and academic research have focused much attention on the dilemma of employees being too busy, this paper presents evidence of the opposite phenomenon, in which employees do not have enough work to fill their time and are left with hours of meaningless idle time each week. We conducted six studies that examine the prevalence and work pacing consequences of involuntary idle time. In a nationally representative cross-occupational survey (Study 1), we found that idle time occurs frequently across all occupational categories; we estimate that employers in the United States pay roughly $100 billion in wages for time that employees spend idle. Studies 2a-3b experimentally demonstrate that there are also collateral consequences of idle time; when workers expect idle time following a task, their work pace declines and their task completion time increases. This decline reverses the well-documented deadline effect, producing a deadtime effect, whereby workers slow down as a task progresses. Our analyses of work pace patterns provide evidence for a time discounting mechanism: workers discount idle time when it is relatively distant, but act to avoid it increasingly as it becomes more proximate. Finally, Study 4 demonstrates that the expectation of being able to engage in leisure activities during posttask free time (e.g., surfing the Internet) can mitigate the collateral work pace losses due to idle time. Through examination and discussion of the effects of idle time at work, we broaden theory on work pacing. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Mind the model: effect of instrumentation on inducibility of atrial fibrillation in a sheep model.

PubMed

Willems, Rik; Holemans, Patricia; Ector, Hugo; Sipido, Karin R; Van de Werf, Frans; Heidbüchel, Hein

2002-01-01

Atrial electrical remodeling, shortening of the atrial effective refractory period (AERP) underlying atrial fibrillation (AF) has been described in different animal models. However, there remains some controversy regarding the time course of this electrical remodeling and the need for secondary factors in the development of AF. We investigated the effect of instrumentation on the inducibility of AF. We hypothesized that epicardial instrumentation could be a confounding factor that accelerates the development of AF. Thirty sheep were rapidly atrially paced at 600 beats/min for 15 weeks: 15 were endocardially instrumented and paced (endo), and 15 were both endocardially and epicardially instrumented. Six of these animals were endocardially paced (sham) and 9 were epicardially paced (epi). The underlying rhythm was determined at regular intervals, and electrophysiologic study was performed. AF developed significantly faster in the epi group. After 3 weeks of pacing, the cumulative incidence of sustained AF (>1 hour) already was 70% in this group versus only 14% and 20% in the endo and sham groups, respectively. After 15 weeks of pacing, this difference was no longer evident. Baseline AERP and minimal AERP, reached before the development of AF, were not significantly different in the three groups. Epicardial instrumentation (epi and sham) increased baseline left and right atrial pressures, but only epicardial stimulation (epi) led to early development of AF. In this sheep model of AF, the experimental setup is a major determinant of the inducibility of AF. Not epicardial instrumentation per se but epicardial stimulation accelerated the development of AF. Different animal models

No Teacher Left behind: How to Teach with Technology

ERIC Educational Resources Information Center

Efaw, Jamie

2005-01-01

With the infusion of technology into all aspects of daily life, students are becoming more and more adept at using technology as an educational resource. Many faculty, however, are not keeping pace with their students. Additionally, faculty feel increasingly unprepared to integrate technology into the classroom. Many institutions of higher learner…

Toward brain-actuated car applications: Self-paced control with a motor imagery-based brain-computer interface.

PubMed

Yu, Yang; Zhou, Zongtan; Yin, Erwei; Jiang, Jun; Tang, Jingsheng; Liu, Yadong; Hu, Dewen

2016-10-01

This study presented a paradigm for controlling a car using an asynchronous electroencephalogram (EEG)-based brain-computer interface (BCI) and presented the experimental results of a simulation performed in an experimental environment outside the laboratory. This paradigm uses two distinct MI tasks, imaginary left- and right-hand movements, to generate a multi-task car control strategy consisting of starting the engine, moving forward, turning left, turning right, moving backward, and stopping the engine. Five healthy subjects participated in the online car control experiment, and all successfully controlled the car by following a previously outlined route. Subject S1 exhibited the most satisfactory BCI-based performance, which was comparable to the manual control-based performance. We hypothesize that the proposed self-paced car control paradigm based on EEG signals could potentially be used in car control applications, and we provide a complementary or alternative way for individuals with locked-in disorders to achieve more mobility in the future, as well as providing a supplementary car-driving strategy to assist healthy people in driving a car. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enact legislation supporting residential property assessed clean energy financing (PACE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saha, Devashree

Congress should enact legislation that supports residential property assessed clean energy (PACE) programs in the nation’s states and metropolitan areas. Such legislation should require the Federal Housing Finance Agency (FHFA) to allow Fannie Mae and Freddie Mac to purchase residential mortgages with PACE assessments while at the same time providing responsible underwriting standards and a set of benchmarks for residential PACE assessments in order to minimize financial risks to mortgage holders. Congressional support of residential PACE financing will improve energy efficiency, encourage job creation, and foster economic growth in the nation’s state and metropolitan areas.

Deficit-Lesion Correlations in Syntactic Comprehension in Aphasia

PubMed Central

Caplan, David; Michaud, Jennifer; Hufford, Rebecca; Makris, Nikos

2015-01-01

The effects of lesions on syntactic comprehension were studied in thirty one people with aphasia (PWA). Participants were tested for the ability to parse and interpret four types of syntactic structures and elements -- passives, object extracted relative clauses, reflexives and pronouns – in three tasks – object manipulation, sentence picture matching with full sentence presentation and sentence picture matching with self-paced listening presentation. Accuracy, end-of-sentence RT and self-paced listening times for each word were measured. MR scans were obtained and analyzed for total lesion volume and for lesion size in 48 cortical areas. Lesion size in several areas of the left hemisphere was related to accuracy in particular sentence types in particular tasks and to self-paced listening times for critical words in particular sentence types. The results support a model of brain organization that includes areas that are specialized for the combination of particular syntactic and interpretive operations and the use of the meanings produced by those operations to accomplish task-related operations. PMID:26688433

Deficit-lesion correlations in syntactic comprehension in aphasia.

PubMed

Caplan, David; Michaud, Jennifer; Hufford, Rebecca; Makris, Nikos

2016-01-01

The effects of lesions on syntactic comprehension were studied in thirty-one people with aphasia (PWA). Participants were tested for the ability to parse and interpret four types of syntactic structures and elements - passives, object extracted relative clauses, reflexives and pronouns - in three tasks - object manipulation, sentence picture matching with full sentence presentation and sentence picture matching with self-paced listening presentation. Accuracy, end-of-sentence RT and self-paced listening times for each word were measured. MR scans were obtained and analyzed for total lesion volume and for lesion size in 48 cortical areas. Lesion size in several areas of the left hemisphere was related to accuracy in particular sentence types in particular tasks and to self-paced listening times for critical words in particular sentence types. The results support a model of brain organization that includes areas that are specialized for the combination of particular syntactic and interpretive operations and the use of the meanings produced by those operations to accomplish task-related operations. Copyright © 2015 Elsevier Inc. All rights reserved.

Prognostic benefit of optimum left ventricular lead position in cardiac resynchronization therapy: follow-up of the TARGET Study Cohort (Targeted Left Ventricular Lead Placement to guide Cardiac Resynchronization Therapy).

PubMed

Kydd, Anna C; Khan, Fakhar Z; Watson, William D; Pugh, Peter J; Virdee, Munmohan S; Dutka, David P

2014-06-01

This study was conducted to assess the impact of left ventricular (LV) lead position on longer-term survival after cardiac resynchronization therapy (CRT). An optimal LV lead position in CRT is associated with improved clinical outcome. A strategy of speckle-tracking echocardiography can be used to guide the implanter to the site of latest activation and away from segments of low strain amplitude (scar). Long-term, prospective survival data according to LV lead position in CRT are limited. Data from a follow-up registry of 250 consecutive patients receiving CRT between June 2008 and July 2010 were studied. The study population comprised patients recruited to the derivation group and the subsequent TARGET (Targeted Left Ventricular Lead Placement to guide Cardiac Resynchronization Therapy) randomized, controlled trial. Final LV lead position was described, in relation to the pacing site determined by pre-procedure speckle-tracking echocardiography, as optimal (concordant/adjacent) or suboptimal (remote). All-cause mortality was recorded at follow-up. An optimal LV lead position (n = 202) conferred LV remodeling response superior to that of a suboptimal lead position (change in LV end-systolic volume: -24 ± 15% vs. -12 ± 17% [p < 0.001]; change in ejection fraction: +7 ± 8% vs. +4 ± 7% [p = 0.02]). During long-term follow-up (median: 39 months; range: <1 to 61 months), an optimal LV lead position was associated with improved survival (log-rank p = 0.003). A suboptimal LV lead placement independently predicted all-cause mortality (hazard ratio: 1.8; p = 0.024). An optimal LV lead position at the site of latest mechanical activation, avoiding low strain amplitude (scar), was associated with superior CRT response and improved survival that persisted during follow-up. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Exercise capacity and N-terminal pro-brain natriuretic peptide levels with biventricular vs. right ventricular pacing for atrioventricular block: results from the PREVENT-HF German Substudy.

PubMed

Stockburger, Martin; de Teresa, Eduardo; Lamas, Gervasio; Desaga, Martin; Koenig, Carsten; Habedank, Dirk; Cobo, Erik; Navarro, Xavier; Wiegand, Uwe

2014-01-01

Previous studies showed unfavourable effects of right ventricular (RV) pacing. Ventricular pacing (VP), however, is required in many patients with atrioventricular (AV) block. The PREVENT-HF study explored left ventricular (LV) remodelling during RV vs. biventricular (BIV) pacing in AV block without advanced heart failure. The pre-specified PREVENT-HF German Substudy examined exercise capacity and N-terminal pro-brain natriuretic peptide (NT-proBNP). Patients with expected VP ≥80% were randomized to RV or BIV pacing. Endpoints were peak oxygen uptake (pVO2), oxygen uptake at the anaerobic threshold (VO2AT), ventilatory efficiency (VE/VCO2), and logNT-proBNP. Considering crossover, intention to treat (ITT), and on-treatment (OT) analyses of covariance (ANCOVA) were performed. For exercise testing 44 (RV: 25, BIV: 19), and for NT-proBNP 53 patients (RV: 29, BIV: 24) were included. The ITT analysis revealed significant differences in pVO2 [ANCOVA effect 2.83 mL/kg/min, confidence interval (CI) 0.83-4.91, P = 0.007], VO2AT (ANCOVA effect 2.14 mL/min/k, CI 0.14-4.15, P = 0.03), and VE/VCO2 (ANCOVA effect -5.46, CI -10.79 to -0.13, P = 0.04) favouring BIV randomization. The significant advantage in pVO2 persisted in OT analysis, while VO2AT and VE/VCO2 showed trends favouring BIV pacing. LogNT-proBNP did not differ between groups. (ITT: ANCOVA effect 0.008, CI -0.40 to +0.41, P = 0.97; OT: ANCOVA effect -0.03, CI -0.44 to 0.30, P = 0.90). Our study suggests that BIV pacing produces better exercise capacity over 1 year compared with RV pacing in patients without advanced heart failure and AV block. In contrast, we observed no significant changes of NT-proBNP. Larger trials will allow appraising the clinical usefulness of BIV pacing in AV block. ClinicalTrials.gov Identifier: NCT00170326.

Using Surveys of Students' Social-Emotional Learning and School Climate for Accountability and Continuous Improvement. Policy Brief 17-1

ERIC Educational Resources Information Center

Hough, Heather; Kalogrides, Demetra; Loeb, Susanna

2017-01-01

The research featured in this paper is part of the CORE-PACE Research Partnership, through which Policy Analysis for California Education (PACE) has partnered with the CORE districts to conduct research designed to support them in continuous improvement while simultaneously helping to improve policy and practice in California and nationwide.…

The effects of husbandry training on stereotypic pacing in captive African wild dogs (Lycaon pictus).

PubMed

Shyne, Amanda; Block, Martin

2010-01-01

To examine the effects of operant conditioning on stereotypic pacing in 3 female African wild dogs located at the Franklin Park Zoo in Boston, this study made recordings of pacing behavior immediately following individual sessions of husbandry training and 2 no-training conditions. The study found significant differences in the percentage of observations spent in stereotypic pacing behaviors for all 3 dogs among the 3 different conditions. The authors discuss the data in terms of the contribution of motivated tasks to the effects and the role of food deprivation in the expression of stereotypic pacing. The study suggests that even short periods of training may improve the African wild dogs' welfare by reducing stereotypic pacing following the conditioning sessions.

Implantation techniques and chronic lead parameters of biventricular pacing dual-chamber defibrillators.

PubMed

Daoud, Emile G; Kalbfleisch, Steven J; Hummel, John D; Weiss, Raul; Augustini, Ralph S; Duff, Steven B; Polsinelli, Georgia; Castor, John; Meta, Tejas

2002-10-01

The aim of this study is to describe implantation techniques and lead performance for biventricular pacing, dual-chamber implantable cardioverter defibrillators (ICDs). A dual-chamber ICD with biventricular pacing was implanted in 87 patients with congestive heart failure (ejection fraction: 0.21 +/- 0.09), prolonged QRS duration (161 +/- 22 msec), and an indication for ICD therapy. Left ventricular pacing was achieved with a thoracotomy approach (n = 21) or a nonthoracotomy approach (n = 66). With a thoracotomy, biventricular devices were implanted successfully in all patients. During follow-up (17 +/- 11 months), 9 patients died (43%), 2 underwent transplantation, and 2 required left ventricular lead revision. At last follow-up, biventricular sensing and capture threshold were 11 +/- 5 mV and 1.5 +/- 0.8 V, respectively. For nonthoracotomy procedures, two types of coronary sinus (CS) leads were implanted: an over-the-wire lead (n = 45) and a shaped lead (n = 21). The rate of successful implantation (overall: 89%) (over-the-wire 93% vs shaped 81%; P = 0.1) and durations for CS lead placement (66 +/- 50 vs 58 +/- 34 min, P = 0.6) and the procedure (133 +/- 58 vs 129 +/- 33 min, P = 0.8) were not different between the two CS leads. During follow-up (11 +/- 9 months), 9 patients died (14%), and the shaped CS lead dislodged in 3 patients (3 shaped vs 0 over-the-wire, P = 0.01). At last follow-up, biventricular sensing and capture threshold were 10 +/- 4 mV and 1.8 +/- 0.7 V, respectively, and there was no difference between over-the-wire and shaped leads. By multivariate analysis, mortality was associated with absence of spironolactone therapy but not procedural features. Nonthoracotomy CS lead implantation is feasible, with a success rate of about 90% and few adverse events. For the remaining 10%, a thoracotomy approach can be completed safely in these ill patients without increased risk for death.

Transferring PACE Assessments Upon Home Sale

DOE Office of Scientific and Technical Information (OSTI.GOV)

National Renewable Energy Laboratory; Coughlin, Jason; Fuller, Merrian

A significant barrier to investing in renewable energy and comprehensive energy efficiency improvements to homes across the country is the initial capital cost. Property Assessed Clean Energy (PACE) financing is one of several new financial models broadening access to clean energy by addressing this upfront cost issue. Recently, the White House cited PACE programs as an important element of its 'Recovery through Retrofit' plan. The residential PACE model involves the creation of a special clean energy financing district that homeowners elect to opt into. Once opted in, the local government (usually at the city or county level) finances the upfrontmore » investment of the renewable energy installation and/or energy efficiency improvements. A special lien is attached to the property and the assessment is paid back as a line item on the property tax bill. As of April 2010, 17 states have passed legislation to allow their local governments to create PACE programs, two already have the authority to set up PACE programs, and over 10 additional states are actively developing enabling legislation. This policy brief analyzes one of the advantages of PACE, which is the transferability of the special assessment from one homeowner to the next when the home is sold. This analysis focuses on the potential for the outstanding lien to impact the sales negotiation process, rather than the legal nature of the lien transfer itself. The goal of this paper is to consider what implications a PACE lien may have on the home sales negotiation process so that it can be addressed upfront rather than risk a future backlash to PACE programs. If PACE programs do expand at a rapid rate, the chances are high that there will be other cases where prospective buyers uses PACE liens to negotiate lower home prices or require repayment of the lien as a condition of sale. As a result, PACE programs should highlight this issue as a potential risk factor for the sake of full disclosure. A good example of this is in Boulder County where the following statement is included in the ClimateSmart PACE program materials: 'Please Note: There is no legal requirement that the loan be paid off when you refinance or sell your home. However, this may be an item subject to negotiation with a future buyer and may also be a matter of negotiation with the mortgage lender.' Such candid disclosure for what might be a low risk event can be debated. However, a selling point of PACE programs is the transferability of the lien to the new homeowner. To the degree this benefit is questioned, PACE programs may end up looking more like home equity loan financing, with the associated debt repaid at closing, rather than property-based financing that remains with the improved home. While it is possible that upfront disclosure might negatively impact participation rates in PACE programs, it also will protect the integrity of a PACE program in later years if such situations come to pass. Ideally, this will become less of an issue over time as more homebuyers understand the positive economic and societal benefits of owning a home with clean energy features.« less

Multimodality Imaging of Myocardial Injury and Remodeling

PubMed Central

Kramer, Christopher M.; Sinusas, Albert J.; Sosnovik, David E.; French, Brent A.; Bengel, Frank M.

2011-01-01

Advances in cardiovascular molecular imaging have come at a rapid pace over the last several years. Multiple approaches have been taken to better understand the structural, molecular, and cellular events that underlie the progression from myocardial injury to myocardial infarction (MI) and, ultimately, to congestive heart failure. Multimodality molecular imaging including SPECT, PET, cardiac MRI, and optical approaches is offering new insights into the pathophysiology of MI and left ventricular remodeling in small-animal models. Targets that are being probed include, among others, angiotensin receptors, matrix metalloproteinases, integrins, apoptosis, macrophages, and sympathetic innervation. It is only a matter of time before these advances are applied in the clinical setting to improve post-MI prognostication and identify appropriate therapies in patients to prevent the onset of congestive heart failure. PMID:20395347

Waiver Hopefuls Put through Paces by Review Process

ERIC Educational Resources Information Center

McNeil, Michele

2012-01-01

Before awarding waivers from core tenets of the No Child Left Behind Act to 11 states, the U.S. Department of Education ordered changes to address a significant weakness in most states' proposals: how they would hold schools accountable for groups of students deemed academically at risk, particularly those in special education or learning English.…

The effect of atrial-based pacing on exercise capacity as measured by the 6-minute walk test: a substudy of the Canadian Trial of Physiological Pacing (CTOPP).

PubMed

Baranchuk, Adrian; Healey, Jeff S; Thorpe, Kevin E; Morillo, Carlos A; Nair, Girish; Crystal, Eugene; Kerr, Charles R; Connolly, Stuart J

2007-08-01

Although several randomized trials have detected no reduction in major cardiovascular events with the routine use of dual-chamber as opposed to ventricular pacemakers, many individuals continue to advocate their use as a means of improving exercise capacity. The Canadian Trial of Physiological Pacing (CTOPP) trial is the largest trial comparing ventricular pacing to atrial-based pacing (atrial or dual-chamber) in patients with bradycardia. All patients in this trial were asked to complete a 6-minute hall walk test (6MWT) at the time of their first study follow-up. The distance walked in 6 minutes and the patient's heart rate before and immediately after the walk were recorded. Of the 2568 patients in the CTOPP, 76% completed the 6MWT. The mean distance walked was 350 +/- 127 m in the ventricular pacing group and 356 +/- 127 m in the atrial-based group (P = NS). Similarly, there was no difference in the change in heart rate between the two groups (17 +/- 13 vs. 18 +/- 12 bpm: P = NS). However, among patients with an unpaced heart rate of

Double valve replacement in a patient with implantable cardioverter defibrillator with severe left ventricular dysfunction.

PubMed

Manjunath, Girish; Rao, Prakash; Prakash, Nagendra; Shivaram, B K

2016-01-01

Recent data from landmark trials suggest that the indications for cardiac pacing and implantable cardioverter defibrillators (ICDs) are set to expand to include heart failure, sleep-disordered breathing, and possibly routine implantation in patients with myocardial infarction and poor ventricular function.[1] This will inevitably result in more patients with cardiac devices undergoing surgeries. Perioperative electromagnetic interference and their potential effects on ICDs pose considerable challenges to the anesthesiologists.[2] We present a case of a patient with automatic ICD with severe left ventricular dysfunction posted for double valve replacement.

Effect of pacing-induced myocardial ischemia on platelet activation and fibrin formation in the coronary circulation.

PubMed

Nichols, A B; Gold, K D; Marcella, J J; Cannon, P J; Owen, J

1987-07-01

The effect of pacing-induced myocardial ischemia on platelet activation and fibrin formation was investigated in seven patients with severe proximal lesions of the left anterior descending coronary artery to determine if acute ischemia activates the coagulation system. Fibrin formation was assessed from plasma levels of fibrinopeptide A. Platelet activation was assessed by levels of platelet factor 4, beta-thromboglobulin and thromboxane B2. Plasma levels were measured before, during and after acute myocardial ischemia induced by rapid atrial pacing. Blood samples were collected from the ascending aorta and from the great cardiac vein through heparin-bonded catheters. The occurrence of anterior myocardial ischemia was established by electrocardiography and by myocardial lactate extraction. No significant transmyocardial gradients in the levels of fibrinopeptide A, platelet factor 4, beta-thromboglobulin or thromboxane B2 were found at rest, during ischemia or in the recovery period, and levels in the great cardiac vein did not change in response to ischemia. These data indicate that pacing-induced myocardial ischemia does not result in release of fibrinopeptide A, platelet factor 4, beta-thromboglobulin or thromboxane B2 into the coronary circulation, and imply that acute ischemia does not induce platelet activation or fibrin formation in the coronary circulation.

42 CFR 460.140 - Additional quality assessment activities.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.140 Additional quality...

Imaging the propagation of the electromechanical wave in heart failure patients with cardiac resynchronization therapy

PubMed Central

Bunting, Ethan; Lambrakos, Litsa; Kemper, Paul; Whang, William; Garan, Hasan; Konofagou, Elisa

2016-01-01

Background Current electrocardiographic and echocardiographic measurements in heart failure (HF) do not take into account the complex interplay between electrical activation and local wall motion. The utilization of novel technologies to better characterize cardiac electromechanical behavior may lead to improved response rates with cardiac resynchronization therapy (CRT). Electromechanical Wave Imaging (EWI) is a non-invasive ultrasound-based technique that uses the transient deformations of the myocardium to track the intrinsic electromechanical wave that precedes myocardial contraction. In this paper, we investigate the performance and reproducibility of EWI in the assessment of HF patients and CRT. Methods EWI acquisitions were obtained in 5 healthy controls and 16 HF patients with and without CRT pacing. Responders (n=8) and non-responders (n=8) to CRT were identified retrospectively on the basis of left ventricular (LV) reverse remodeling. Electromechanical activation maps were obtained in all patients and used to compute a quantitative parameter describing the mean activation time of the LV lateral wall (LWAT). Results Mean LWAT was increased by 52.1 ms in HF patients in native rhythm compared to controls (p<0.01). For all HF patients, CRT pacing initiated a different electromechanical activation sequence. Responders exhibited a 56.4±28.9 ms reduction in LWAT with CRT pacing (p<0.01), while non-responders showed no significant change. Conclusion In this initial feasibility study, EWI was capable of characterizing local cardiac electromechanical behavior as it pertains to HF and CRT response. Activation sequences obtained with EWI allow for quantification of LV lateral wall electromechanical activation, thus providing a novel method for CRT assessment. PMID:27790723

A slow-releasing form of prostacyclin agonist (ONO1301SR) enhances endogenous secretion of multiple cardiotherapeutic cytokines and improves cardiac function in a rapid-pacing-induced model of canine heart failure.

PubMed

Shirasaka, Tomonori; Miyagawa, Shigeru; Fukushima, Satsuki; Saito, Atsuhiro; Shiozaki, Motoko; Kawaguchi, Naomasa; Matsuura, Nariaki; Nakatani, Satoshi; Sakai, Yoshiki; Daimon, Takashi; Okita, Yutaka; Sawa, Yoshiki

2013-08-01

Cardiac functional deterioration in dilated cardiomyopathy (DCM) is known to be reversed by intramyocardial up-regulation of multiple cardioprotective factors, whereas a prostacyclin analog, ONO1301, has been shown to paracrinally activate interstitial cells to release a variety of protective factors. We here hypothesized that intramyocardial delivery of a slow-releasing form of ONO1301 (ONO1301SR) might activate regional myocardium to up-regulate cardiotherapeutic factors, leading to regional and global functional recovery in DCM. ONO1301 elevated messenger RNA and protein level of hepatocyte growth factor, vascular endothelial growth factor, and stromal-derived factor-1 of normal human dermal fibroblasts in a dose-dependent manner in vitro. Intramyocardial delivery of ONO1301SR, which is ONO1301 mixed with polylactic and glycolic acid polymer (PLGA), but not that of PLGA only, yielded significant global functional recovery in a canine rapid pacing-induced DCM model, assessed by echocardiography and cardiac catheterization (n = 5 each). Importantly, speckle-tracking echocardiography unveiled significant regional functional recovery in the ONO1301-delivered territory, consistent to significantly increased vascular density, reduced interstitial collagen accumulation, attenuated myocyte hypertrophy, and reversed mitochondrial structure in the corresponding area. Intramyocardial delivery of ONO1301SR, which is a PLGA-coated slow-releasing form of ONO1301, up-regulated multiple cardiotherapeutic factors in the injected territory, leading to region-specific reverse left ventricular remodeling and consequently a global functional recovery in a rapid-pacing-induced canine DCM model, warranting a further preclinical study to optimize this novel drug-delivery system to treat DCM. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Long pacing pulses reduce phrenic nerve stimulation in left ventricular pacing.

PubMed

Hjortshøj, Søren; Heath, Finn; Haugland, Morten; Eschen, Ole; Thøgersen, Anna Margrethe; Riahi, Sam; Toft, Egon; Struijk, Johannes Jan

2014-05-01

Phrenic nerve stimulation is a major obstacle in cardiac resynchronization therapy (CRT). Activation characteristics of the heart and phrenic nerve are different with higher chronaxie for the heart. Therefore, longer pulse durations could be beneficial in preventing phrenic nerve stimulation during CRT due to a decreased threshold for the heart compared with the phrenic nerve. We investigated if long pulse durations decreased left ventricular (LV) thresholds relatively to phrenic nerve thresholds in humans. Eleven patients, with indication for CRT and phrenic nerve stimulation at the intended pacing site, underwent determination of thresholds for the heart and phrenic nerve at different pulse durations (0.3-2.9 milliseconds). The resulting strength duration curves were analyzed by determining chronaxie and rheobase. Comparisons for those parameters were made between the heart and phrenic nerve, and between the models of Weiss and Lapicque as well. In 9 of 11 cases, the thresholds decreased faster for the LV than for the phrenic nerve with increasing pulse duration. In 3 cases, the thresholds changed from unfavorable for LV stimulation to more than a factor 2 in favor of the LV. The greatest change occurred for pulse durations up to 1.5 milliseconds. The chronaxie of the heart was significantly higher than the chronaxie of the phrenic nerve (0.47 milliseconds vs. 0.22 milliseconds [P = 0.029, Lapicque] and 0.79 milliseconds vs. 0.27 milliseconds [P = 0.033, Weiss]). Long pulse durations lead to a decreased threshold of the heart relatively to the phrenic nerve and may prevent stimulation of the phrenic nerve in a clinical setting. © 2013 Wiley Periodicals, Inc.

Position paper for management of elderly patients with pacemakers and implantable cardiac defibrillators: Groupe de Rythmologie et Stimulation Cardiaque de la Société Française de Cardiologie and Société Française de Gériatrie et Gérontologie.

PubMed

Fauchier, Laurent; Alonso, Christine; Anselme, Frederic; Blangy, Hugues; Bordachar, Pierre; Boveda, Serge; Clementy, Nicolas; Defaye, Pascal; Deharo, Jean-Claude; Friocourt, Patrick; Gras, Daniel; Halimi, Franck; Klug, Didier; Mansourati, Jacques; Obadia, Benjamin; Pasquié, Jean-Luc; Pavin, Dominique; Sadoul, Nicolas; Taieb, Jerome; Piot, Olivier; Hanon, Olivier

2016-10-01

Despite the increasingly high rate of implantation of pacemakers (PMs) and implantable cardioverter defibrillators (ICDs) in elderly patients, data supporting their clinical and cost-effectiveness in this age stratum are ambiguous and contradictory. We reviewed the data regarding the applicability, safety and effectiveness of conventional pacing, ICDs and cardiac resynchronization therapy (CRT) in elderly patients. Although periprocedural risk may be slightly higher in the elderly, the implantation procedure for PMs and ICDs is still relatively safe in this age group. In older patients with sinus node disease, the general consensus is that DDD pacing with the programming of an algorithm to minimize ventricular pacing is preferred. In very old patients presenting with intermittent or suspected atrioventricular block, VVI pacing may be appropriate. In terms of correcting potentially life-threatening arrhythmias, the effectiveness of ICD therapy is similar in older and younger individuals. However, the assumption of persistent ICD benefit in the elderly population is questionable, as any advantageous effect of the device on arrhythmic death may be attenuated by higher total non-arrhythmic mortality. While septuagenarians and octogenarians have higher annual all-cause mortality rates, ICD therapy may remain effective in selected patients at high risk of arrhythmic death and with minimum comorbidities despite advanced age. ICD implantation among the elderly, as a group, may not be cost-effective, but the procedure may reach cost-effectiveness in those expected to live more than 5-7years after implantation. Elderly patients usually experience significant functional improvement after CRT, similar to that observed in middle-aged patients. Management of CRT non-responders remains globally the same, while considering a less aggressive approach in terms of reinterventions (revision of left ventricular [LV] lead placement, addition of a right ventricular or LV lead, LV endocardial pacing configuration). Overall, physiological age, general status and comorbidities rather than chronological age per se should be the decisive factors in making a decision about device implantation selection for survival and well-being benefit in elderly patients. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Comparing maximum rate and sustainability of pacing by mechanical vs. electrical stimulation in the Langendorff-perfused rabbit heart.

PubMed

Quinn, T Alexander; Kohl, Peter

2016-12-01

Mechanical stimulation (MS) represents a readily available, non-invasive means of pacing the asystolic or bradycardic heart in patients, but benefits of MS at higher heart rates are unclear. Our aim was to assess the maximum rate and sustainability of excitation by MS vs. electrical stimulation (ES) in the isolated heart under normal physiological conditions. Trains of local MS or ES at rates exceeding intrinsic sinus rhythm (overdrive pacing; lowest pacing rates 2.5±0.5 Hz) were applied to the same mid-left ventricular free-wall site on the epicardium of Langendorff-perfused rabbit hearts. Stimulation rates were progressively increased, with a recovery period of normal sinus rhythm between each stimulation period. Trains of MS caused repeated focal ventricular excitation from the site of stimulation. The maximum rate at which MS achieved 1:1 capture was lower than during ES (4.2±0.2 vs. 5.9±0.2 Hz, respectively). At all overdrive pacing rates for which repetitive MS was possible, 1:1 capture was reversibly lost after a finite number of cycles, even though same-site capture by ES remained possible. The number of MS cycles until loss of capture decreased with rising stimulation rate. If interspersed with ES, the number of MS to failure of capture was lower than for MS only. In this study, we demonstrate that the maximum pacing rate at which MS can be sustained is lower than that for same-site ES in isolated heart, and that, in contrast to ES, the sustainability of successful 1:1 capture by MS is limited. The mechanism(s) of differences in MS vs. ES pacing ability, potentially important for emergency heart rhythm management, are currently unknown, thus warranting further investigation. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

Voltage and pace-capture mapping of linear ablation lesions overestimates chronic ablation gap size.

PubMed

O'Neill, Louisa; Harrison, James; Chubb, Henry; Whitaker, John; Mukherjee, Rahul K; Bloch, Lars Ølgaard; Andersen, Niels Peter; Dam, Høgni; Jensen, Henrik K; Niederer, Steven; Wright, Matthew; O'Neill, Mark; Williams, Steven E

2018-04-26

Conducting gaps in lesion sets are a major reason for failure of ablation procedures. Voltage mapping and pace-capture have been proposed for intra-procedural identification of gaps. We aimed to compare gap size measured acutely and chronically post-ablation to macroscopic gap size in a porcine model. Intercaval linear ablation was performed in eight Göttingen minipigs with a deliberate gap of ∼5 mm left in the ablation line. Gap size was measured by interpolating ablation contact force values between ablation tags and thresholding at a low force cut-off of 5 g. Bipolar voltage mapping and pace-capture mapping along the length of the line were performed immediately, and at 2 months, post-ablation. Animals were euthanized and gap sizes were measured macroscopically. Voltage thresholds to define scar were determined by receiver operating characteristic analysis as <0.56 mV (acutely) and <0.62 mV (chronically). Taking the macroscopic gap size as gold standard, error in gap measurements were determined for voltage, pace-capture, and ablation contact force maps. All modalities overestimated chronic gap size, by 1.4 ± 2.0 mm (ablation contact force map), 5.1 ± 3.4 mm (pace-capture), and 9.5 ± 3.8 mm (voltage mapping). Error on ablation contact force map gap measurements were significantly less than for voltage mapping (P = 0.003, Tukey's multiple comparisons test). Chronically, voltage mapping and pace-capture mapping overestimated macroscopic gap size by 11.9 ± 3.7 and 9.8 ± 3.5 mm, respectively. Bipolar voltage and pace-capture mapping overestimate the size of chronic gap formation in linear ablation lesions. The most accurate estimation of chronic gap size was achieved by analysis of catheter-myocardium contact force during ablation.

Comparing maximum rate and sustainability of pacing by mechanical vs. electrical stimulation in the Langendorff-perfused rabbit heart

PubMed Central

Quinn, T. Alexander; Kohl, Peter

2016-01-01

Aims Mechanical stimulation (MS) represents a readily available, non-invasive means of pacing the asystolic or bradycardic heart in patients, but benefits of MS at higher heart rates are unclear. Our aim was to assess the maximum rate and sustainability of excitation by MS vs. electrical stimulation (ES) in the isolated heart under normal physiological conditions. Methods and results Trains of local MS or ES at rates exceeding intrinsic sinus rhythm (overdrive pacing; lowest pacing rates 2.5±0.5 Hz) were applied to the same mid-left ventricular free-wall site on the epicardium of Langendorff-perfused rabbit hearts. Stimulation rates were progressively increased, with a recovery period of normal sinus rhythm between each stimulation period. Trains of MS caused repeated focal ventricular excitation from the site of stimulation. The maximum rate at which MS achieved 1:1 capture was lower than during ES (4.2±0.2 vs. 5.9±0.2 Hz, respectively). At all overdrive pacing rates for which repetitive MS was possible, 1:1 capture was reversibly lost after a finite number of cycles, even though same-site capture by ES remained possible. The number of MS cycles until loss of capture decreased with rising stimulation rate. If interspersed with ES, the number of MS to failure of capture was lower than for MS only. Conclusion In this study, we demonstrate that the maximum pacing rate at which MS can be sustained is lower than that for same-site ES in isolated heart, and that, in contrast to ES, the sustainability of successful 1:1 capture by MS is limited. The mechanism(s) of differences in MS vs. ES pacing ability, potentially important for emergency heart rhythm management, are currently unknown, thus warranting further investigation. PMID:28011835

Estimation of the effects of multipoint pacing on battery longevity in routine clinical practice.

PubMed

Akerström, Finn; Narváez, Irene; Puchol, Alberto; Pachón, Marta; Martín-Sierra, Cristina; Rodríguez-Mañero, Moisés; Rodríguez-Padial, Luis; Arias, Miguel A

2017-09-23

Multipoint pacing (MPP) permits simultaneous multisite pacing of the left ventricle (LV); initial studies suggest haemodynamic and clinical benefits over conventional (single LV site) cardiac resynchronization therapy (CRT). The aim of this study was to estimate the impact of MPP activation on battery longevity in routine clinical practice. Patient (n = 46) and device data were collected from two centres at least 3 months after MPP-CRT device implantation. Multipoint pacing programming was based on the maximal possible anatomical LV1/LV2 separation according to three predefined LV pacing capture threshold (PCT) cut-offs (≤1.5 V; ≤4.0 V; and ≤6.5 V). Estimated battery longevity was calculated using the programmed lower rate limit, lead impedances, outputs, and pacing percentages. Relative to the longevity for conventional CRT using the lowest PCT (8.9 ± 1.2 years), MPP activation significantly shortened battery longevity for all three PCT cut-offs (≤1.5 V, -5.6%; ≤4.0 V, -16.9%; ≤6.5 V, -21.3%; P's <0.001). When compared with conventional CRT based on longest right ventricle-LV delay (8.3 ± 1.3 years), battery longevity was significantly shortened for the MPP ≤ 4.0 V and ≤6.5 V cut-offs (-10.8 and -15.7%, respectively; P's <0.001). Maximal LV1/LV2 spacing was possible in 23.9% (≤1.5 V), 56.5% (≤4.0 V), and 69.6% (≤6.5 V) of patients. Multipoint pacing activation significantly reduces battery longevity compared with that for conventional CRT configuration. When reasonable MPP LV vector PCTs (≤4.0 V) are achieved, the decrease in battery longevity is relatively small which may prompt the clinician to activate MPP. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Bachmann's Bundle Pacing not Only Improves Interatrial Conduction but Also Reduces the Need for Ventricular Pacing.

PubMed

Sławuta, Agnieszka; Kliś, Magdalena; Skoczyński, Przemysław; Bańkowski, Tomasz; Moszczyńska-Stulin, Joanna; Gajek, Jacek

2016-01-01

Patients treated for sick sinus syndrome may have interatrial conduction disorder leading to atrial fibrillation. This study was aimed to assess the influence of the atrial pacing site on interatrial and atrioventricular conduction as well as the percentage of ventricular pacing in patients with sick sinus syndrome implanted with atrioventricular pacemaker. The study population: 96 patients (58 females, 38 males) aged 74.1 ± 11.8 years were divided in two groups: Group 1 (n = 44) with right atrial appendage pacing and group 2 (n = 52) with Bachmann's area pacing. We assessed the differences in atrioventricular conduction in sinus rhythm and atrial 60 and 90 bpm pacing, P-wave duration and percentage of ventricular pacing. No differences in baseline P-wave duration in sinus rhythm between the groups (102.4 ± 17 ms vs. 104.1 ± 26 ms, p = ns.) were noted. Atrial pacing 60 bpm resulted in longer P-wave in group 1 vs. group 2 (138.3 ± 21 vs. 106.1 ± 15 ms, p < 0.01). The differences between atrioventricular conduction time during sinus rhythm and atrial pacing at 60 and 90 bpm were significantly longer in patients with right atrial appendage vs. Bachmann's pacing (44.1 ± 17 vs. 9.2 ± 7 ms p < 0.01 and 69.2 ± 31 vs. 21.4 ± 12 ms p < 0.05, respectively). The percentage of ventricular pacing was higher in group 1 (21 vs. 4%, p < 0.01). Bachmann's bundle pacing decreases interatrial and atrioventricular conduction delay. Moreover, the frequency-dependent atrioventricular conduction lengthening is much less pronounced during Bachmann's bundle pacing. Right atrial appendage pacing in sick sinus syndrome patients promotes a higher percentage of ventricular pacing.

Assessing the PACE of California residential solar deployment: Impacts of Property Assessed Clean Energy programs on residential solar photovoltaic deployment in California, 2010-2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deason, Jeff; Murphy, Sean

A new study by Berkeley Lab found that residential Property Assessed Clean Energy (R-PACE) programs increased deployment of residential solar photovoltaic (PV) systems in California, raising it by about 7-12% in cities that adopt these programs. R-PACE is a financing mechanism that uses a voluntary property tax assessment, paid off over time, to facilitate energy improvements and, in some jurisdictions, water and resilience measures. While previous studies demonstrated that early, regional R-PACE programs increased solar PV deployment, this new analysis is the first to demonstrate these impacts from the large, statewide R-PACE programs dominating the California market today, which usemore » private capital to fund the upfront costs of the improvements. Berkeley Lab estimated the impacts using econometric techniques on two samples: -Large cities only, allowing annual demographic and economic data as control variables -All California cities, without these annual data Analysis of both samples controls for several factors other than R-PACE that would be expected to drive solar PV deployment. We infer that on average, cities with R-PACE programs were associated with greater solar PV deployment in our study period (2010-2015). In the large cities sample, solar PV deployment in jurisdictions with R-PACE programs was higher by 1.1 watts per owner-occupied household per month, or 12%. Across all cities, solar PV deployment in jurisdictions with R-PACE programs was higher by 0.6 watts per owner-occupied household per month, or 7%. The large cities results are statistically significant at conventional levels; the all-cities results are not. The estimates imply that the majority of solar PV deployment financed by R-PACE programs would likely not have occurred in their absence. Results suggest that R-PACE programs have increased PV deployment in California even in relatively recent years, as R-PACE programs have grown in market share and as alternate approaches for financing solar PV have developed. The U.S. Department of Energy’s Building Technologies Office supported this research.« less

Application synergies between the NASA Pre- Aerosol Cloud and ocean Ecosystem (PACE) and Hyperspectral Infrared Imager (HyspIRI) missions

NASA Astrophysics Data System (ADS)

Lee, C. M.; Omar, A. H.; Hook, S. J.; Tzortziou, M.; Luvall, J. C.; Turner, W. W.

2016-02-01

Observations from the Pre-Aerosol Cloud and ocean Ecosystem (PACE) and Hyperspectral InfraRed Imager (HyspIRI) satellite missions are highly complementary and have the potential to significantly advance understanding of various science and applications challenges in the ocean sciences and water quality communities. Scheduled for launch in the 2022 timeframe, PACE is designed to make climate-quality global measurements essential for understanding ocean biology, biogeochemistry and ecology, and determining the role of the ocean in global biogeochemical cycling and ocean ecology, and how it affects and is affected by climate change. PACE will provide high signal-to-noise, hyperspectral observations over an extended spectral range (UV to SWIR) and will have global coverage every 1-2 days, at approximately 1 km spatial resolution; furthermore, PACE is currently designed to include a polarimeter, which will vastly improve atmospheric correction algorithms over water bodies. The PACE mission will enable advances in applications across a range of areas, including oceans, climate, water resources, ecological forecasting, disasters, human health and air quality. HyspIRI, with contiguous measurements in VSWIR, and multispectral measurements in TIR, will be able to provide detailed spectral observations and higher spatial resolution (30 to 60-m) over aquatic systems, but at a temporal resolution that is approximately 5-16 days. HyspIRI would enable improved, detailed studies of aquatic ecosystems, including benthic communities, algal blooms, coral reefs, and wetland species distribution as well as studies of water quality indicators or pollutants such as oil spills, suspended sediment, and colored dissolved organic matter. Together, PACE and HyspIRI will be able to address numerous applications and science priorities, including improving and extending climate data records, and studies of inland, coastal and ocean environments.

Improving Responsiveness to Intervention for English-Language Learners: A Comparison of Instructional Pace on Letter Naming Rates

ERIC Educational Resources Information Center

Gilbertson, Donna; Bluck, John

2006-01-01

An alternating treatments design was used to compare the effects of a 1-s and a 5-s paced intervention on rates of letter naming by English Language Learners (ELL). Participants were four kindergarten students performing below the average letter naming level and learning rate than other ELL classmates. The fast paced intervention consisted of a…

Transvenous pacemaker electrodes placed unintentionally in the left ventricle: three cases.

PubMed Central

Winner, S. J.; Boon, N. A.

1989-01-01

Three patients are described in whom pacemaker electrodes were unintentionally placed within the left ventricle, followed by considerable delay before the error was recognized. In two cases temporary pacemaker wires were inserted into the subclavian artery and passed along a retrograde course. One patient required urgent surgery for acute arterial obstruction on removal of the wire. In the third case, a permanent wire was inserted correctly into a vein but traversed the atrial septum, probably via a patent foramen ovale, to enter the left ventricle. Twelve lead electrocardiograms in all three patients showed paced complexes with right bundle branch block configuration. This appearance should raise suspicion that the pacemaker electrode might be in the left ventricle, in which case its position should be defined by chest radiographs (including a lateral view) and echocardiography. Images Figure 1 Figure 3 Figure 4 PMID:2780472

Do implantable cardioverter defibrillators improve survival in patients with severe left ventricular systolic dysfunction after coronary artery bypass graft surgery?

PubMed

Fazal, Iftikhar A; Bates, Matthew G D; Matthews, Iain G; Turley, Andrew J

2011-06-01

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether implantable cardioverter defibrillators (ICD) improve survival in patients with severe left ventricular systolic dysfunction (LVSD) after coronary artery bypass graft (CABG) surgery. ICDs are designed to terminate potentially fatal cardiac tachyarrhythmias. A right ventricular lead is mandatory for detection, pacing and defibrillation capabilities. Dual chamber ICDs have an additional right atrial lead and are used for patients with conventional atrioventricular pacing indications. More sophisticated, biventricular devices exist to provide cardiac resynchronisation therapy (CRT) in addition to defibrillation (CRT-D). ICDs have been extensively investigated in patients with LVSD post myocardial infarction and in patients with non-ischaemic cardiomyopathy for both secondary prevention (history of ventricular arrhythmias) and primary prevention (deemed high risk for ventricular arrhythmias). This best evidence topic aims to review the evidence and its applicability to patients post CABG. Nine hundred and sixteen papers were identified using the search method outlined. Eight randomised controlled trials, two meta-analyses, and one non-randomised trial, in addition to international guidelines presented the best evidence to answer the clinical question. The current evidence base and guidelines suggest that ICDs should be considered for all patients with LVSD [ejection fraction (EF) ≤30-40%] receiving optimal pharmacological management, who are ≥40 days post MI [four weeks for National Institute for Health and Clinical Excellence (NICE)] and in New York Heart Association (NYHA) class I-III. UK NICE guidelines require in addition; non-sustained ventricular tachycardia (NSVT) on a Holter monitor and inducible ventricular tachycardia at electrophysiological study for EF between 30 and 35%; or a QRS >120 ms if EF <30%. The North American guidelines recommend EF <30% as a threshold for those with NYHA class I symptoms. The evidence is applicable to patients post CABG, provided all the other criteria are met. European Society of Cardiology (ESC) guidelines recommend waiting at least three months (consensus opinion) after revascularisation prior to assessment for an ICD, to allow time for potential recovery of ventricular function.

Noninvasive reconstruction of the three-dimensional ventricular activation sequence during pacing and ventricular tachycardia in the canine heart.

PubMed

Han, Chengzong; Pogwizd, Steven M; Killingsworth, Cheryl R; He, Bin

2012-01-01

Single-beat imaging of myocardial activation promises to aid in both cardiovascular research and clinical medicine. In the present study we validate a three-dimensional (3D) cardiac electrical imaging (3DCEI) technique with the aid of simultaneous 3D intracardiac mapping to assess its capability to localize endocardial and epicardial initiation sites and image global activation sequences during pacing and ventricular tachycardia (VT) in the canine heart. Body surface potentials were measured simultaneously with bipolar electrical recordings in a closed-chest condition in healthy canines. Computed tomography images were obtained after the mapping study to construct realistic geometry models. Data analysis was performed on paced rhythms and VTs induced by norepinephrine (NE). The noninvasively reconstructed activation sequence was in good agreement with the simultaneous measurements from 3D cardiac mapping with a correlation coefficient of 0.74 ± 0.06, a relative error of 0.29 ± 0.05, and a root mean square error of 9 ± 3 ms averaged over 460 paced beats and 96 ectopic beats including premature ventricular complexes, couplets, and nonsustained monomorphic VTs and polymorphic VTs. Endocardial and epicardial origins of paced beats were successfully predicted in 72% and 86% of cases, respectively, during left ventricular pacing. The NE-induced ectopic beats initiated in the subendocardium by a focal mechanism. Sites of initial activation were estimated to be ∼7 mm from the measured initiation sites for both the paced beats and ectopic beats. For the polymorphic VTs, beat-to-beat dynamic shifts of initiation site and activation pattern were characterized by the reconstruction. The present results suggest that 3DCEI can noninvasively image the 3D activation sequence and localize the origin of activation of paced beats and NE-induced VTs in the canine heart with good accuracy. This 3DCEI technique offers the potential to aid interventional therapeutic procedures for treating ventricular arrhythmias arising from epicardial or endocardial sites and to noninvasively assess the mechanisms of these arrhythmias.

Noninvasive reconstruction of the three-dimensional ventricular activation sequence during pacing and ventricular tachycardia in the canine heart

PubMed Central

Han, Chengzong; Pogwizd, Steven M.; Killingsworth, Cheryl R.

2012-01-01

Single-beat imaging of myocardial activation promises to aid in both cardiovascular research and clinical medicine. In the present study we validate a three-dimensional (3D) cardiac electrical imaging (3DCEI) technique with the aid of simultaneous 3D intracardiac mapping to assess its capability to localize endocardial and epicardial initiation sites and image global activation sequences during pacing and ventricular tachycardia (VT) in the canine heart. Body surface potentials were measured simultaneously with bipolar electrical recordings in a closed-chest condition in healthy canines. Computed tomography images were obtained after the mapping study to construct realistic geometry models. Data analysis was performed on paced rhythms and VTs induced by norepinephrine (NE). The noninvasively reconstructed activation sequence was in good agreement with the simultaneous measurements from 3D cardiac mapping with a correlation coefficient of 0.74 ± 0.06, a relative error of 0.29 ± 0.05, and a root mean square error of 9 ± 3 ms averaged over 460 paced beats and 96 ectopic beats including premature ventricular complexes, couplets, and nonsustained monomorphic VTs and polymorphic VTs. Endocardial and epicardial origins of paced beats were successfully predicted in 72% and 86% of cases, respectively, during left ventricular pacing. The NE-induced ectopic beats initiated in the subendocardium by a focal mechanism. Sites of initial activation were estimated to be ∼7 mm from the measured initiation sites for both the paced beats and ectopic beats. For the polymorphic VTs, beat-to-beat dynamic shifts of initiation site and activation pattern were characterized by the reconstruction. The present results suggest that 3DCEI can noninvasively image the 3D activation sequence and localize the origin of activation of paced beats and NE-induced VTs in the canine heart with good accuracy. This 3DCEI technique offers the potential to aid interventional therapeutic procedures for treating ventricular arrhythmias arising from epicardial or endocardial sites and to noninvasively assess the mechanisms of these arrhythmias. PMID:21984548

Multistage electrotherapy delivered through chronically-implanted leads terminates atrial fibrillation with lower energy than a single biphasic shock.

PubMed

Janardhan, Ajit H; Gutbrod, Sarah R; Li, Wenwen; Lang, Di; Schuessler, Richard B; Efimov, Igor R

The goal of this study was to develop a low-energy, implantable device-based multistage electrotherapy (MSE) to terminate atrial fibrillation (AF). Previous attempts to perform cardioversion of AF by using an implantable device were limited by the pain caused by use of a high-energy single biphasic shock (BPS). Transvenous leads were implanted into the right atrium (RA), coronary sinus, and left pulmonary artery of 14 dogs. Self-sustaining AF was induced by 6 ± 2 weeks of high-rate RA pacing. Atrial defibrillation thresholds of standard versus experimental electrotherapies were measured in vivo and studied by using optical imaging in vitro. The mean AF cycle length (CL) in vivo was 112 ± 21 ms (534 beats/min). The impedances of the RA-left pulmonary artery and RA-coronary sinus shock vectors were similar (121 ± 11 Ω vs. 126 ± 9 Ω; p = 0.27). BPS required 1.48 ± 0.91 J (165 ± 34 V) to terminate AF. In contrast, MSE terminated AF with significantly less energy (0.16 ± 0.16 J; p < 0.001) and significantly lower peak voltage (31.1 ± 19.3 V; p < 0.001). In vitro optical imaging studies found that AF was maintained by localized foci originating from pulmonary vein-left atrium interfaces. MSE Stage 1 shocks temporarily disrupted localized foci; MSE Stage 2 entrainment shocks continued to silence the localized foci driving AF; and MSE Stage 3 pacing stimuli enabled consistent RA-left atrium activation until sinus rhythm was restored. Low-energy MSE significantly reduced the atrial defibrillation thresholds compared with BPS in a canine model of AF. MSE may enable painless, device-based AF therapy. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Multistage Electrotherapy Delivered Through Chronically-Implanted Leads Terminates Atrial Fibrillation With Lower Energy Than a Single Biphasic Shock

PubMed Central

Janardhan, Ajit H.; Gutbrod, Sarah R.; Li, Wenwen; Lang, Di; Schuessler, Richard B.; Efimov, Igor R.

2014-01-01

Objectives The goal of this study was to develop a low-energy, implantable device–based multistage electrotherapy (MSE) to terminate atrial fibrillation (AF). Background Previous attempts to perform cardioversion of AF by using an implantable device were limited by the pain caused by use of a high-energy single biphasic shock (BPS). Methods Transvenous leads were implanted into the right atrium (RA), coronary sinus, and left pulmonary artery of 14 dogs. Self-sustaining AF was induced by 6 ± 2 weeks of high-rate RA pacing. Atrial defibrillation thresholds of standard versus experimental electrotherapies were measured in vivo and studied by using optical imaging in vitro. Results The mean AF cycle length (CL) in vivo was 112 ± 21 ms (534 beats/min). The impedances of the RA–left pulmonary artery and RA–coronary sinus shock vectors were similar (121 ± 11 Ω vs. 126 ± 9 Ω; p = 0.27). BPS required 1.48 ± 0.91 J (165 ± 34 V) to terminate AF. In contrast, MSE terminated AF with significantly less energy (0.16 ± 0.16 J; p < 0.001) and significantly lower peak voltage (31.1 ± 19.3 V; p < 0.001). In vitro optical imaging studies found that AF was maintained by localized foci originating from pulmonary vein–left atrium interfaces. MSE Stage 1 shocks temporarily disrupted localized foci; MSE Stage 2 entrainment shocks continued to silence the localized foci driving AF; and MSE Stage 3 pacing stimuli enabled consistent RA–left atrium activation until sinus rhythm was restored. Conclusions Low-energy MSE significantly reduced the atrial defibrillation thresholds compared with BPS in a canine model of AF. MSE may enable painless, device-based AF therapy. PMID:24076284

Drowning in Debt: The Emerging Student Loan Crisis. Charts You Can Trust

ERIC Educational Resources Information Center

Dillon, Erin; Carey, Kevin

2009-01-01

The authors find that college students are borrowing more and taking on riskier forms of debt than ever before. If tuition increases continue to grow faster than inflation and family income and grant aid fails to keep pace, the authors project that more students will be left with few choices beyond student loans--and, increasingly, private loans.…

A Comprehensive Analysis of High School Genetics Standards: Are States Keeping Pace with Modern Genetics?

ERIC Educational Resources Information Center

Dougherty, M. J.; Pleasants, C.; Solow, L.; Wong, A.; Zhang, H.

2011-01-01

Science education in the United States will increasingly be driven by testing and accountability requirements, such as those mandated by the No Child Left Behind Act, which rely heavily on learning outcomes, or "standards," that are currently developed on a state-by-state basis. Those standards, in turn, drive curriculum and instruction.…

Active metabolite of GLP-1 mediates myocardial glucose uptake and improves left ventricular performance in conscious dogs with dilated cardiomyopathy.

PubMed

Nikolaidis, Lazaros A; Elahi, Dariush; Shen, You-Tang; Shannon, Richard P

2005-12-01

We have shown previously that the glucagon-like peptide-1 (GLP-1)-(7-36) amide increases myocardial glucose uptake and improves left ventricular (LV) and systemic hemodynamics in both conscious dogs with pacing-induced dilated cardiomyopathy (DCM) and humans with LV systolic dysfunction after acute myocardial infarction. However, GLP-1-(7-36) is rapidly degraded in the plasma to GLP-1-(9-36) by dipeptidyl peptidase IV (DPP IV), raising the issue of which peptide is the active moiety. By way of methodology, we compared the efficacy of a 48-h continuous intravenous infusion of GLP-1-(7-36) (1.5 pmol.kg(-1).min(-1)) to GLP-1-(9-36) (1.5 pmol.kg(-1).min(-1)) in 28 conscious, chronically instrumented dogs with pacing-induced DCM by measuring LV function and transmyocardial substrate uptake under basal and insulin-stimulated conditions using hyperinsulinemic-euglycemic clamps. As a result, dogs with DCM demonstrated myocardial insulin resistance under basal and insulin-stimulated conditions. Both GLP-1-(7-36) and GLP-1-(9-36) significantly reduced (P < 0.01) LV end-diastolic pressure [GLP-1-(7-36), 28 +/- 1 to 15 +/- 2 mmHg; GLP-1-(9-36), 29 +/- 2 to 16 +/- 1 mmHg] and significantly increased (P < 0.01) the first derivative of LV pressure [GLP-1-(7-36), 1,315 +/- 81 to 2,195 +/- 102 mmHg/s; GLP-1-(9-36), 1,336 +/- 77 to 2,208 +/- 68 mmHg] and cardiac output [GLP-1-(7-36), 1.5 +/- 0.1 to 1.9 +/- 0.1 l/min; GLP-1-(9-36), 2.0 +/- 0.1 to 2.4 +/- 0.05 l/min], whereas an equivolume infusion of saline had no effect. Both peptides increased myocardial glucose uptake but without a significant increase in plasma insulin. During the GLP-1-(9-36) infusion, negligible active (NH2-terminal) peptide was measured in the plasma. In conclusion, in DCM, GLP-1-(9-36) mimics the effects of GLP-1-(7-36) in stimulating myocardial glucose uptake and improving LV and systemic hemodynamics through insulinomimetic as opposed to insulinotropic effects. These data suggest that GLP-1-(9-36) amide is an active peptide.

Improving MRCP PACES pass rates through the introduction of a regional multifaceted support framework

PubMed Central

Jerrom, Richard; Roper, Tayeba; Murthy, Narasimha

2017-01-01

Introduction Practical Assessment of Clinical Examination Skills (PACES) constitutes the final part of the mandatory Royal College of Physicians exam series for progression to higher specialty training. Pass rates were lower for core medical trainees (CMTs) in Coventry and Warwickshire in comparison to other regions within the West Midlands and nationally. Objectives Our aim was to improve pass rates in the region through the introduction of a stimulating and supportive teaching framework, designed to enhance the quality and frequency of PACES teaching. Methods To identify key areas for change a baseline questionnaire, including Likert Scale and free text questions related to PACES teaching, was distributed to all CMTs in the region. Many trainees highlighted concern over lack of PACES-orientated teaching and support, with particular emphasis on: lack of bedside-teaching with feedback; infrequent opportunities for practising communication skills; and difficulty identifying suitable patients in an efficient manner. To address these concerns the following interventions were implemented over two Plan, Do, Study, Act (PDSA) cycles which were analysed at 6 months and 12months: a digital forum to highlight relevant inpatients for examination practice; a peer-to-peer mentoring scheme; a consultant-led bedside-teaching rota; and classroom-based communication skills sessions. Results Pass rates at Annual Review of Competence Progression improved from baseline to the end of the first year of implementation, 56.3% to 77.3%, respectively. Furthermore, following analysis of questionnaires at each PDSA cycle, we demonstrated a progressive improvement in trainee satisfaction in exposure, quality and relevance of teaching. Conclusion Our innovative, cost-effective teaching framework for PACES preparation has improved exam outcomes and facilitated swift junior doctor career progression, while raising the profile of the trust. Furthermore, this innovation provides a template for potential adoption in other National Health Service institutions. PMID:28959777

Sawtooth pacing by real-time auxiliary power control in a tokamak plasma.

PubMed

Goodman, T P; Felici, F; Sauter, O; Graves, J P

2011-06-17

In the standard scenario of tokamak plasma operation, sawtooth crashes are the main perturbations that can trigger performance-degrading, and potentially disruption-generating, neoclassical tearing modes. This Letter demonstrates sawtooth pacing by real-time control of the auxiliary power. It is shown that the sawtooth crash takes place in a reproducible manner shortly after the removal of that power, and this can be used to precisely prescribe, i.e., pace, the individual sawteeth. In combination with preemptive stabilization of the neoclassical tearing modes, sawtooth pacing provides a new sawtooth control paradigm for improved performance in burning plasmas.

Ventricular untwisting: a temporal link between left ventricular relaxation and suction.

PubMed

Notomi, Yuichi; Popovic, Zoran B; Yamada, Hirotsugu; Wallick, Don W; Martin, Maureen G; Oryszak, Stephanie J; Shiota, Takahiro; Greenberg, Neil L; Thomas, James D

2008-01-01

Left ventricular (LV) untwisting starts early during the isovolumic relaxation phase and proceeds throughout the early filling phase, releasing elastic energy stored by the preceding systolic deformation. Data relating untwisting, relaxation, and intraventricular pressure gradients (IVPG), which represent another manifestation of elastic recoil, are sparse. To understand the interaction between LV mechanics and inflow during early diastole, Doppler tissue images (DTI), catheter-derived pressures (apical and basal LV, left atrial, and aortic), and LV volume data were obtained at baseline, during varying pacing modes, and during dobutamine and esmolol infusion in seven closed-chest anesthetized dogs. LV torsion and torsional rate profiles were analyzed from DTI data sets (apical and basal short-axis images) with high temporal resolution (6.5 +/- 0.7 ms). Repeated-measures regression models showed moderately strong correlation of peak LV twisting with peak LV untwisting rate (r = 0.74), as well as correlations of peak LV untwisting rate with the time constant of LV pressure decay (tau, r = -0.66) and IVPG (r = 0.76, P < 0.0001 for all). In a multivariate analysis, peak LV untwisting rate was an independent predictor of tau and IVPG (P < 0.0001, for both). The start of LV untwisting coincided with the beginning of relaxation and preceded suction-aided filling resulting from elastic recoil. Untwisting rate may be a useful marker of diastolic function or even serve as a therapeutic target for improving diastolic function.

Self-Paced Instruction: Hello, Education

ERIC Educational Resources Information Center

Leuba, Richard J.; Flammer, Gordon H.

1975-01-01

Answers criticisms of self-paced instruction (SPI) by citing advantages of SPI over lecture methods. Concludes that criticisms of SPI are useful since they indicate in which areas further research should be conducted to improve this method of instruction. (MLH)

Electrocardiographic Predictors of Long-Term Cardiac Pacing Dependency Following Transcatheter Aortic Valve Implantation.

PubMed

Naveh, Sivan; Perlman, Gidon Y; Elitsur, Yair; Planer, David; Gilon, Dan; Leibowitz, David; Lotan, Chaim; Danenberg, Haim; Alcalai, Ronny

2017-02-01

Conduction disorders requiring permanent pacemaker (PPM) implantation are a known complication of transcatheter aortic valve implantation (TAVI). Indications for permanent pacing in this setting are still controversial. The study aim was to characterize the natural history of conduction disorders related to TAVI, and to identify predictors for long-term pacing dependency. Consecutive patients who underwent TAVI were included in this prospective observational study. The conduction system was investigated by reviewing 12-lead ECGs during hospitalization and up to 1-year follow-up and by analyzing pacemaker interrogation data. Multivariate analysis was performed in order to identify independent predictors for pacemaker dependency. Of 110 patients included in the analysis, 38 (34.5%) underwent PPM implantation. Of those, 26 (68.4%) had a long-term pacing dependency (required PPM), while 12 (31.6%) did not (not-required PPM). Logistic regression revealed that baseline RBBB (P = 0.01, OR = 18.0), baseline PR interval (P = 0.019, OR = 1.14), post-TAVI PR interval and the change in PR interval from baseline (P < 0.001 for both, OR = 1.17 for each 10 milliseconds increment) were independent predictors for long-term pacing dependency. A PR interval increment of greater than 28 milliseconds had the best accuracy in predicting pacemaker dependency. Increased pre- and postprocedural PR intervals and pre-existing RBBB are reliable predictors for long-term PPM dependency, while left bundle branch block or QRS width are misleading factors. Our study suggests that the decision for implanting PPM after TAVI should be based mostly on the prolongation of the PR interval. © 2016 Wiley Periodicals, Inc.

A two-class self-paced BCI to control a robot in four directions.

PubMed

Ron-Angevin, Ricardo; Velasco-Alvarez, Francisco; Sancha-Ros, Salvador; da Silva-Sauer, Leandro

2011-01-01

In this work, an electroencephalographic analysis-based, self-paced (asynchronous) brain-computer interface (BCI) is proposed to control a mobile robot using four different navigation commands: turn right, turn left, move forward and move back. In order to reduce the probability of misclassification, the BCI is to be controlled with only two mental tasks (relaxed state versus imagination of right hand movements), using an audio-cued interface. Four healthy subjects participated in the experiment. After two sessions controlling a simulated robot in a virtual environment (which allowed the user to become familiar with the interface), three subjects successfully moved the robot in a real environment. The obtained results show that the proposed interface enables control over the robot, even for subjects with low BCI performance. © 2011 IEEE

Left and Right Ventricle Leads Switch as a Solution for TWave Oversensing - How a Good Idea Turned Out Bad.

PubMed

Alzand, Bsn; Phlips, Tje; Willems, R

2014-05-01

A 50-year-old male with a CRT defibrillator received inappropriate ICD shocks due to T-wave oversensing. Decreasing the sensitivity to avoid T wave oversensing was not an option due to a suboptimal R-wave sensing amplitude. We decided to re-plug the LV lead in the RV port and the RV lead in the LV port. This however led to intermittent phrenic nerve stimulation due to mandatory bipolar (tip-ring) or unipolar (tip-can) pacing on the LV-lead from the RV port. Re-intervention was necessary with the implantation of an additional pacing/sensing RV lead. A software programmable choice to switch sensing and tachycardia detection from RV to LV lead could be a valuable feature in future CRT devices.

Altering Pace Control and Pace Regulation: Attentional Focus Effects during Running.

PubMed

Brick, Noel E; Campbell, Mark J; Metcalfe, Richard S; Mair, Jacqueline L; Macintyre, Tadhg E

2016-05-01

To date, there are no published studies directly comparing self-controlled (SC) and externally controlled (EC) pace endurance tasks. However, previous research suggests pace control may impact on cognitive strategy use and effort perceptions. The primary aim of this study was to investigate the effects of manipulating perception of pace control on attentional focus, physiological, and psychological outcomes during running. The secondary aim was to determine the reproducibility of self-paced running performance when regulated by effort perceptions. Twenty experienced endurance runners completed four 3-km time trials on a treadmill. Subjects completed two SC pace trials, one perceived exertion clamped (PE) trial, and one EC pace time trial. PE and EC were completed in a counterbalanced order. Pacing strategy for EC and perceived exertion instructions for PE replicated the subjects' fastest SC time trial. Subjects reported a greater focus on cognitive strategies such as relaxing and optimizing running action during EC than during SC. The mean HR was 2% lower during EC than that during SC despite an identical pacing strategy. Perceived exertion did not differ between the three conditions. However, increased internal sensory monitoring coincided with elevated effort perceptions in some subjects during EC and a 10% slower completion time for PE (13.0 ± 1.6 min) than that for SC (11.8 ± 1.2 min). Altering pace control and pace regulation impacted on attentional focus. External control over pacing may facilitate performance, particularly when runners engage attentional strategies conducive to improved running efficiency. However, regulating pace based on effort perceptions alone may result in excessive monitoring of bodily sensations and a slower running speed. Accordingly, attentional focus interventions may prove beneficial for some athletes to adopt task-appropriate attentional strategies to optimize performance.

Constant DI pacing suppresses cardiac alternans formation in numerical cable models

NASA Astrophysics Data System (ADS)

Zlochiver, S.; Johnson, C.; Tolkacheva, E. G.

2017-09-01

Cardiac repolarization alternans describe the sequential alternation of the action potential duration (APD) and can develop during rapid pacing. In the ventricles, such alternans may rapidly turn into life risking arrhythmias under conditions of spatial heterogeneity. Thus, suppression of alternans by artificial pacing protocols, or alternans control, has been the subject of numerous theoretical, numerical, and experimental studies. Yet, previous attempts that were inspired by chaos control theories were successful only for a short spatial extent (<2 cm) from the pacing electrode. Previously, we demonstrated in a single cell model that pacing with a constant diastolic interval (DI) can suppress the formation of alternans at high rates of activation. We attributed this effect to the elimination of feedback between the pacing cycle length and the last APD, effectively preventing restitution-dependent alternans from developing. Here, we extend this idea into cable models to study the extent by which constant DI pacing can control alternans during wave propagation conditions. Constant DI pacing was applied to ventricular cable models of up to 5 cm, using human kinetics. Our results show that constant DI pacing significantly shifts the onset of both cardiac alternans and conduction blocks to higher pacing rates in comparison to pacing with constant cycle length. We also demonstrate that constant DI pacing reduces the propensity of spatially discordant alternans, a precursor of wavebreaks. We finally found that the protective effect of constant DI pacing is stronger for increased electrotonic coupling along the fiber in the sense that the onset of alternans is further shifted to higher activation rates. Overall, these results support the potential clinical applicability of such type of pacing in improving protocols of implanted pacemakers, in order to reduce the risk of life-threatening arrhythmias. Future research should be conducted in order to experimentally validate these promising results.

Recommendations for pacemaker implantation for the treatment of atrial tachyarrhythmias and resynchronisation therapy for heart failure: A report from the task force on pacemaker indications of the Dutch Working Group on Cardiac Pacing.

PubMed

van Hemel, N M; Dijkman, B; de Voogt, W G; Beukema, W P; Bosker, H A; de Cock, C C; Jordaens, L J L M; van Gelder, I C; van Gelder, L M; van Mechelen, R; Ruiter, J H; Sedney, M I; Slegers, L C

2004-01-01

Today, new pacing algorithms and stimulation methods for the prevention and interruption of atrial tachyarrhythmias can be applied on patients who need bradycardia pacing for conventional reasons. In addition, biventricular pacing as additive treatment for patients with severe congestive heart failure due to ventricular systolic dysfunction and prolonged intraventricular conduction has shown to improve symptoms and reduce hospital admissions. These new pacing technologies and the optimising of the pacing programmes are complex, expensive and time-consuming. Based on many clinical studies the indications for these devices are beginning to emerge. To support the cardiologist's decision-making and to prevent waste of effort and resources, the 'ad hoc committee' has provided preliminary recommendations for implantable devices to treat atrial tachyarrhythmias and to extend the treatment of congestive heart failure respectively.

Continuous directed evolution of aminoacyl-tRNA synthetases

PubMed Central

Bryson, David I.; Fan, Chenguang; Guo, Li-Tao; Miller, Corwin; Söll, Dieter; Liu, David R.

2017-01-01

Directed evolution of orthogonal aminoacyl-tRNA synthetases (AARSs) enables site-specific installation of non-canonical amino acids (ncAAs) into proteins. Traditional evolution techniques typically produce AARSs with greatly reduced activity and selectivity compared to their wild-type counterparts. We designed phage-assisted continuous evolution (PACE) selections to rapidly produce highly active and selective orthogonal AARSs through hundreds of generations of evolution. PACE of a chimeric Methanosarcina spp. pyrrolysyl-tRNA synthetase (PylRS) improved its enzymatic efficiency (kcat/KMtRNA) 45-fold compared to the parent enzyme. Transplantation of the evolved mutations into other PylRS-derived synthetases improved yields of proteins containing non-canonical residues up to 9.7-fold. Simultaneous positive and negative selection PACE over 48 h greatly improved the selectivity of a promiscuous Methanocaldococcus jannaschii tyrosyl-tRNA synthetase variant for site-specific incorporation of p-iodo-L-phenylalanine. These findings offer new AARSs that increase the utility of orthogonal translation systems and establish the capability of PACE to efficiently evolve orthogonal AARSs with high activity and amino acid specificity. PMID:29035361

Effect of an 8-week practice of externally triggered speech on basal ganglia activity of stuttering and fluent speakers.

PubMed

Toyomura, Akira; Fujii, Tetsunoshin; Kuriki, Shinya

2015-04-01

The neural mechanisms underlying stuttering are not well understood. It is known that stuttering appears when persons who stutter speak in a self-paced manner, but speech fluency is temporarily increased when they speak in unison with external trigger such as a metronome. This phenomenon is very similar to the behavioral improvement by external pacing in patients with Parkinson's disease. Recent imaging studies have also suggested that the basal ganglia are involved in the etiology of stuttering. In addition, previous studies have shown that the basal ganglia are involved in self-paced movement. Then, the present study focused on the basal ganglia and explored whether long-term speech-practice using external triggers can induce modification of the basal ganglia activity of stuttering speakers. Our study of functional magnetic resonance imaging revealed that stuttering speakers possessed significantly lower activity in the basal ganglia than fluent speakers before practice, especially when their speech was self-paced. After an 8-week speech practice of externally triggered speech using a metronome, the significant difference in activity between the two groups disappeared. The cerebellar vermis of stuttering speakers showed significantly decreased activity during the self-paced speech in the second compared to the first experiment. The speech fluency and naturalness of the stuttering speakers were also improved. These results suggest that stuttering is associated with defective motor control during self-paced speech, and that the basal ganglia and the cerebellum are involved in an improvement of speech fluency of stuttering by the use of external trigger. Copyright © 2015 Elsevier Inc. All rights reserved.

High-fidelity simulation of transcutaneous cardiac pacing: characteristics and limitations of available high-fidelity simulators, and description of an alternative two-mannequin model.

PubMed

Robitaille, Arnaud; Perron, Roger; Germain, Jean-François; Tanoubi, Issam; Georgescu, Mihai

2015-04-01

Transcutaneous cardiac pacing (TCP) is a potentially lifesaving technique that is part of the recommended treatment for symptomatic bradycardia. Transcutaneous cardiac pacing however is used uncommonly, and its successful application is not straightforward. Simulation could, therefore, play an important role in the teaching and assessment of TCP competence. However, even the highest-fidelity mannequins available on the market have important shortcomings, which limit the potential of simulation. Six criteria defining clinical competency in TCP were established and used as a starting point in the creation of an improved TCP simulator. The goal was a model that could be used to assess experienced clinicians, an objective that justifies the additional effort required by the increased fidelity. The proposed 2-mannequin model (TMM) combines a highly modified Human Patient Simulator with a SimMan 3G, the latter being used solely to provide the electrocardiography (ECG) tracing. The TMM improves the potential of simulation to assess experienced clinicians (1) by reproducing key features of TCP, like using the same multifunctional pacing electrodes used clinically, allowing dual ECG monitoring, and responding with upper body twitching when stimulated, but equally importantly (2) by reproducing key pitfalls of the technique, like allowing pacing electrode misplacement and reproducing false signs of ventricular capture, commonly, but erroneously, used clinically to establish that effective pacing has been achieved (like body twitching, electrical artifact on the ECG, and electrical capture without ventricular capture). The proposed TMM uses a novel combination of 2 high-fidelity mannequins to improve TCP simulation until upgraded mannequins become commercially available.

Arrhythmia causes lipid accumulation and reduced glucose uptake.

PubMed

Lenski, Matthias; Schleider, Gregor; Kohlhaas, Michael; Adrian, Lucas; Adam, Oliver; Tian, Qinghai; Kaestner, Lars; Lipp, Peter; Lehrke, Michael; Maack, Christoph; Böhm, Michael; Laufs, Ulrich

2015-01-01

Atrial fibrillation (AF) is characterized by irregular contractions of atrial cardiomyocytes and increased energy demand. The aim of this study was to characterize the influence of arrhythmia on glucose and fatty acid (FA) metabolism in cardiomyocytes, mice and human left atrial myocardium. Compared to regular pacing, irregular (pseudo-random variation at the same number of contractions/min) pacing of neonatal rat cardiomyocytes induced shorter action potential durations and effective refractory periods and increased diastolic [Ca(2+)]c. This was associated with the activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and AMP-activated protein kinase (AMPK). Membrane expression of fatty acid translocase (FAT/CD36) and (14)C-palmitic acid uptake were augmented while membrane expression of glucose transporter subtype 4 (GLUT-4) as well as (3)H-glucose uptake were reduced. Inhibition of AMPK and CaMKII prevented these arrhythmia-induced metabolic changes. Similar alterations of FA metabolism were observed in a transgenic mouse model (RacET) for spontaneous AF. Consistent with these findings samples of left atrial myocardium of patients with AF compared to matched samples of patients with sinus rhythm showed up-regulation of CaMKII and AMPK and increased membrane expression of FAT/CD36, resulting in lipid accumulation. These changes of FA metabolism were accompanied by decreased membrane expression of GLUT-4, increased glycogen content and increased expression of the pro-apoptotic protein bax. Irregular pacing of cardiomyocytes increases diastolic [Ca(2+)]c and activation of CaMKII and AMPK resulting in lipid accumulation, reduced glucose uptake and increased glycogen synthesis. These metabolic changes are accompanied by an activation of pro-apoptotic signalling pathways.

Physiological response of cardiac tissue to bisphenol a: alterations in ventricular pressure and contractility

PubMed Central

Brooks, Daina; Chandra, Akhil; Jaimes, Rafael; Sarvazyan, Narine; Kay, Matthew

2015-01-01

Biomonitoring studies have indicated that humans are routinely exposed to bisphenol A (BPA), a chemical that is commonly used in the production of polycarbonate plastics and epoxy resins. Epidemiological studies have shown that BPA exposure in humans is associated with cardiovascular disease; however, the direct effects of BPA on cardiac physiology are largely unknown. Previously, we have shown that BPA exposure slows atrioventricular electrical conduction, decreases epicardial conduction velocity, and prolongs action potential duration in excised rat hearts. In the present study, we tested if BPA exposure also adversely affects cardiac contractile performance. We examined the impact of BPA exposure level, sex, and pacing rate on cardiac contractile function in excised rat hearts. Hearts were retrogradely perfused at constant pressure and exposed to 10−9-10−4 M BPA. Left ventricular developed pressure and contractility were measured during sinus rhythm and during pacing (5, 6.5, and 9 Hz). Ca2+ transients were imaged from whole hearts and from neonatal rat cardiomyocyte layers. During sinus rhythm in female hearts, BPA exposure decreased left ventricular developed pressure and inotropy in a dose-dependent manner. The reduced contractile performance was exacerbated at higher pacing rates. BPA-induced effects on contractile performance were also observed in male hearts, albeit to a lesser extent. Exposure to BPA altered Ca2+ handling within whole hearts (reduced diastolic and systolic Ca2+ transient potentiation) and neonatal cardiomyocytes (reduced Ca2+ transient amplitude and prolonged Ca2+ transient release time). In conclusion, BPA exposure significantly impaired cardiac performance in a dose-dependent manner, having a major negative impact upon electrical conduction, intracellular Ca2+ handing, and ventricular contractility. PMID:25980024

Moving to Music: Effects of Heard and Imagined Musical Cues on Movement-Related Brain Activity

PubMed Central

Schaefer, Rebecca S.; Morcom, Alexa M.; Roberts, Neil; Overy, Katie

2014-01-01

Music is commonly used to facilitate or support movement, and increasingly used in movement rehabilitation. Additionally, there is some evidence to suggest that music imagery, which is reported to lead to brain signatures similar to music perception, may also assist movement. However, it is not yet known whether either imagined or musical cueing changes the way in which the motor system of the human brain is activated during simple movements. Here, functional magnetic resonance imaging was used to compare neural activity during wrist flexions performed to either heard or imagined music with self-pacing of the same movement without any cueing. Focusing specifically on the motor network of the brain, analyses were performed within a mask of BA4, BA6, the basal ganglia (putamen, caudate, and pallidum), the motor nuclei of the thalamus, and the whole cerebellum. Results revealed that moving to music compared with self-paced movement resulted in significantly increased activation in left cerebellum VI. Moving to imagined music led to significantly more activation in pre-supplementary motor area (pre-SMA) and right globus pallidus, relative to self-paced movement. When the music and imagery cueing conditions were contrasted directly, movements in the music condition showed significantly more activity in left hemisphere cerebellum VII and right hemisphere and vermis of cerebellum IX, while the imagery condition revealed more significant activity in pre-SMA. These results suggest that cueing movement with actual or imagined music impacts upon engagement of motor network regions during the movement, and suggest that heard and imagined cues can modulate movement in subtly different ways. These results may have implications for the applicability of auditory cueing in movement rehabilitation for different patient populations. PMID:25309407

Thrombo-embolic events in left ventricular endocardial pacing: long-term outcomes from a multicentre UK registry.

PubMed

Sawhney, Vinit; Domenichini, Giulia; Gamble, James; Furniss, Guy; Panagopoulos, Dimitrios; Lambiase, Pier; Rajappan, Kim; Chow, Anthony; Lowe, Martin; Sporton, Simon; Earley, Mark J; Dhinoja, Mehul; Campbell, Niall; Hunter, Ross J; Haywood, Guy; Betts, Tim R; Schilling, Richard J

2018-06-01

Endocardial left ventricular (LV) pacing is a viable alternative in patients with failed coronary sinus (CS) lead implantation. However, long-term thrombo-embolic risk remains unknown. Much of the data have come from a small number of centres. We examined the safety and efficacy of endocardial LV pacing to determine the long-term thrombo-embolic risk. Registries from four UK centres were combined to include 68 patients with endocardial leads with a mean follow-up of 20 months. These were compared to a matched 1:2 control group with conventional CS leads. Medical records were reviewed, and patients contacted for follow-up. Ischaemic stroke occurred in four patients (6%) in the endocardial arm providing an annual event rate (AER) of 3.6% over a 20 month follow-up; compared to 9 patients (6.6%) amongst controls with an AER of 3.4% over a 23-month follow-up. Regression analyses showed a significant association between sub-therapeutic international normalized ratio and stroke (P = 0.0001) in the endocardial arm. There was no association between lead material and mode of delivery (transatrial/transventricular) and stroke. Mortality rate was 12 and 15 per 100 patient years in the endocardial and control arm respectively with end-stage heart failure being the commonest cause. Endocardial LV lead in heart failure patients has a good success rate at 1.6 year follow-up. However, it is associated with a thrombo-embolic risk (which is not different from conventional CS leads) attributable to sub-therapeutic anticoagulation. Randomized control trials and studies on non-vitamin K antagonist oral anticoagulants are required to ascertain the potential of widespread clinical application of this therapeutic modality.

Effect of Right Ventricular versus Biventricular Pacing on Electrical Remodeling in the Normal Heart

PubMed Central

Saba, Samir; Mehdi, Haider; Mathier, Michael A.; Islam, M. Zahadul; Salama, Guy; London, Barry

2010-01-01

Background Biventricular (BIV) pacing can improve cardiac function in heart failure by altering the mechanical and electrical substrates. We investigated the effect of BIV versus right ventricular (RV) pacing on the normal heart. Methods and Results Male New Zealand White rabbits (n=33) were divided into 3 groups: sham-operated (control), RV pacing, and BIV pacing groups. Four weeks after surgery, the native QT (p=0.004) interval was significantly shorter in the BIV group compared to the RV or sham-operated groups. Also, compared to rabbits in the RV group, rabbits in the BIV group had shorter RV ventricular effective refractory period (VERP) at all cycle lengths, and shorter LV paced QT interval during the drive train of stimuli and close to refractoriness (p<0.001 for all comparisons). Protein expression of the KVLQT1 was significantly increased in the BIV group compared to the RV and control groups, while protein expression of SCN5A and connexin43 was significantly decreased in the RV compared to the other study groups. Erg protein expression was significantly increased in both pacing groups compared to the controls. Conclusions In this rabbit model, we demonstrate a direct effect of BIV but not RV pacing on shortening the native QT interval as well as the paced QT interval during burst pacing and close to the VERP. These findings underscore the fact that the effect of BIV pacing is partially mediated through direct electrical remodeling and may have implications as to the effect of BIV pacing on arrhythmia incidence and burden. PMID:20042767

Interatrial septum versus right atrial appendage pacing for prevention of atrial fibrillation : A meta-analysis of randomized controlled trials.

PubMed

Zhang, L; Jiang, H; Wang, W; Bai, J; Liang, Y; Su, Y; Ge, J

2017-07-28

Interatrial septum (IAS) pacing seems to be a promising strategy for the prevention of atrial fibrillation (AF); however, studies have yielded conflicting results. This meta-analysis was to compare IAS with right atrial appendage (RAA) pacing on the prevention of postpacing AF occurrence. Pubmed, MEDLINE, EMBASE and Web of Science databases were searched through October 2016 for randomized controlled trials comparing IAS with RAA pacing on the prevention of AF. Data concerning study design, patient characteristics and outcomes were extracted. Risk ratio (RR), weighted mean differences (WMD) or standardized mean differences (SMD) were calculated using fixed or random effects models. A total of 12 trials involving 1146 patients with dual-chamber pacing were included. Although IAS was superior to RAA pacing in terms of reducing the number of AF episodes (SMD = -0.29, P = 0.05), AF burden (SMD = -0.41, P = 0.008) and P -wave duration (WMD = -34.45 ms, P < 0.0001), neither permanent AF occurrence (RR = 0.94, P = 0.58) nor recurrences of AF (RR = 0.88, P = 0.36) were reduced by IAS pacing. Nevertheless, no differences were observed concerning all-cause death (RR = 1.04, P = 0.88), procedure-related events (RR = 1.17, P = 0.69) and pacing parameters between IAS and RAA pacing in the follow-up period. IAS pacing is safe and as well tolerated as RAA pacing. Although IAS pacing may fail to prevent permanent AF occurrence and recurrences of AF, it is able to not only improve interatrial conduction, but also reduce AF burden.

Different horse's paces during hippotherapy on spatio-temporal parameters of gait in children with bilateral spastic cerebral palsy: A feasibility study.

PubMed

Antunes, Fabiane Nunes; Pinho, Alexandre Severo do; Kleiner, Ana Francisca Rozin; Salazar, Ana Paula; Eltz, Giovana Duarte; de Oliveira Junior, Alcyr Alves; Cechetti, Fernanda; Galli, Manuela; Pagnussat, Aline Souza

2016-12-01

Hippotherapy is often carried out for the rehabilitation of children with Cerebral Palsy (CP), with the horse riding at a walking pace. This study aimed to explore the immediate effects of a hippotherapy protocol using a walk-trot pace on spatio-temporal gait parameters and muscle tone in children with Bilateral Spastic CP (BS-CP). Ten children diagnosed with BS-CP and 10 healthy aged-matched children (reference group) took part in this study. The children with BS-CP underwent two sessions of hippotherapy for one week of washout between them. Two protocols (lasting 30min) were applied on separate days: Protocol 1: the horse's pace was a walking pace; and Protocol 2: the horse's pace was a walk-trot pace. Children from the reference group were not subjected to treatment. A wireless inertial measurement unit measured gait spatio-temporal parameters before and after each session. The Modified Ashworth Scale was applied for muscle tone measurement of hip adductors. The participants underwent the gait assessment on a path with surface irregularities (ecological context). The comparisons between BS-CP and the reference group found differences in all spatio-temporal parameters, except for gait velocity. Within-group analysis of children with BS-CP showed that the swing phase did not change after the walk pace and after the walk-trot pace. The percentage of rolling phase and double support improved after the walk-trot. The spasticity of the hip adductors was significantly reduced as an immediate result of both protocols, but this decrease was more evident after the walk-trot. The walk-trot protocol is feasible and is able to induce an immediate effect that improves the gait spatio-temporal parameters and the hip adductors spasticity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of atorvastatin on atrial remodeling in a rabbit model of atrial fibrillation produced by rapid atrial pacing.

PubMed

Yang, Qian; Qi, Xiaoyong; Dang, Yi; Li, Yingxiao; Song, Xuelian; Hao, Xiao

2016-06-24

Accumulating evidence suggests that myeloperoxidase (MPO) is involved in atrial remodeling of atrial fibrillation (AF). Statins could reduce the MPO levels in patients with cardiovascular diseases. This study evaluated the effects of atorvastatin on MPO level and atrial remodeling in a rabbit model of pacing-induced AF. Eighteen rabbits were randomly divided into sham, control and atorvastatin groups. Rabbits in the control and atorvastatin groups were subjected to rapid atrial pacing (RAP) at 600 bpm for 3 weeks, and treated with placebo or atorvastatin (2.5 mg/kg/d), respectively. Rabbits in the sham group did not receive RAP. After 3 weeks of pacing, atrial structural and functional changes were assessed by echocardiography, atrial effective refractory period (AERP) and AF inducibility were measured by atrial electrophysiological examination, and histological changes were evaluated by Masson trichrome-staining. The L-type calcium channel α1c (Cav1.2), collagen I and III, MPO, matrix metalloproteinase (MMP)-2 and MMP-9 were analyzed by real time polymerase chain reaction and/or western blot. All rabbits were found to have maintained sinus rhythm after 3 weeks of RAP. Atrial burst stimulation induced sustained AF (>30 min) in 5, 4, and no rabbits in the control, atorvastatin, and sham groups, respectively. The AERP shortened and Cav1.2 mRNA level decreased in the control group, but these changes were suppressed in the atorvastatin group. Obvious left atrial enlargement and dysfunction was found in both control and atorvastatin groups. Compared with the control group, these echocardiograhic indices of left atrium did not differ in the atorvastatin group. Prominent atrial fibrosis and increased levels of collagen I and III were observed in the control group but not in the atorvastatin group. The mRNA and protein levels of MPO, MMP-2 and MMP-9 significantly increased in the control group, but these changes were prevented in the atorvastatin group. Treatment with atorvastatin prevented atrial remodeling in a rabbit model of RAP-induced AF. The reduction of levels of atrial MPO, MMP-2 and MMP-9 may contribute to the prevention of atorvastatin on atrial remodeling.

Large animal model of functional tricuspid regurgitation in pacing induced end-stage heart failure.

PubMed

Malinowski, Marcin; Proudfoot, Alistair G; Langholz, David; Eberhart, Lenora; Brown, Michael; Schubert, Hans; Wodarek, Jeremy; Timek, Tomasz A

2017-06-01

Functional tricuspid regurgitation (FTR) is common in patients with advanced heart failure and frequently complicates left ventricular assist device implantation yet remains poorly understood. We set out to establish large animal model of FTR that could serve as a research platform to investigate the pathogenesis of FTR associated with end-stage heart failure. : Through right thoracotomy, ten adult sheep underwent implantation of pacemaker with epicardial LV lead, five sonomicrometry crystals on the right ventricle, and left and right ventricular telemetry pressure sensors during a beating heart off-pump procedure. After 5 ± 1 days of recovery, baseline haemodynamic, echocardiographic and sonomicrometry data were collected. Animals were paced thereafter at a rate of 220-240 beats/min until the development of heart failure and concomitant tricuspid regurgitation. : Three animals died during early recovery period and one during the pacing phase. Six surviving animals were paced for a mean of 14 ± 5 days. Cardiac function was significantly depressed compared to baseline, with LV ejection fraction falling from 69 ± 2% to 22 ± 4% ( P  < 0.001) and RV fractional area change from 52 ± 11% to 25 ± 9% ( P  = 0.005). All animals developed significant enlargement of tricuspid annulus (from 29.5 ± 1.6 to 36.5 ± 4.5 mm; P  = 0.01) and right ventricle (from 21.9 ± 0.2 to 30.3 ± 0.6 mm; P  = 0.03). Sonomicrometry derived contractility of RV free wall was depressed and at least moderate tricuspid insufficiency developed in all animals. : Biventricular dysfunction, tricuspid annular dilatation and significant FTR were observed in our model of ovine tachycardia induced cardiomyopathy. This animal model reflects the clinical situation of end-stage heart failure patients presenting for mechanical support. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

The effects of metronome breathing on the variability of autonomic activity measurements.

PubMed

Driscoll, D; Dicicco, G

2000-01-01

Many chiropractors hypothesize that spinal manipulation affects the autonomic nervous system (ANS). However, the ANS responses to chiropractic manipulative therapy are not well documented, and more research is needed to support this hypothesis. This study represents a step toward the development of a reliable method by which to document that chiropractic manipulative therapy does affect the ANS by exploring the use of paced breathing as a way to reduce the inherent variability in ANS measurements. To examine the hypothesis that the variability of ANS measurements would be reduced if breathing were paced to a metronome at 12 breaths/min. The study was performed at Parker College Research Institute. Eight normotensive subjects were recruited from the student body and staff. Respiration frequency was measured through a strain gauge. A 3-lead electrocardiogram (ECG) was used to register the electric activity of the heart, and arterial tonometry monitors were used to record the left and right radial artery blood pressures. Signals were recorded on an IBM-compatible computer with a sampling frequency of 100 Hz. Normal breathing was used for the first 3 recordings, and breathing was paced to a metronome for the final 3 recordings at 12 breaths/min. Fourier analysis was performed on the beat-by-beat fluctuations of the ECG-determined R-R interval and systolic arterial pressure (SBP). Low-frequency fluctuations (LF; 0.04-0.15 Hz) reflected sympathetic activity, whereas high-frequency fluctuations (HF; 0.15-0.4 Hz) represented parasympathetic activity. Sympathovagal indices were determined from the ratio of the two bandwidths (LF/HF). The coefficient of variation (CV%) for autonomic parameters was calculated ([average/SD] x 100%) to compare breathing normally and breathing to a metronome with respect to variability. One-way analysis of variance was used to detect differences. A value of P < 0.05 was considered statistically significant; all results are presented as average +/- SD. Three male and 5 female normotensive subjects were studied. Metronome breathing did not produce any significant changes in blood pressure for the left and right radial arteries, heart rate, or pressure pulse transmission time. Breathing to a metronome increased ECG-HF power (0.25 +/- 0.07 vs 0.35 +/- 0.09, P < 0.04), decreased ECG-LF/HF (1.08 +/- 0.55 vs 0.57 +/- 0.35, P < 0.05), and reduced the CV% for ECG-LF (47.6% +/- 23.4% vs 23.8% +/- 14.6%, P < 0.03), ECG-HF (46.2% +/- 14.2% vs 25.8% +/- 17.0%, P < 0.03) and ECG-LF/HF (50.1% +/- 27.6% vs 23.4% +/- 12.3%, P < 0.03) in comparison with normal breathing. Metronome breathing increased the left and right radial artery SBP-HF fluctuations (left, 0.11 +/- 0.05 vs 0.30 +/- 0.16, P < 0.007; right, 0.09 +/- 0.05 vs 0.27 +/- 0.15, P < 0.008) and decreased the SBP-LF/HF components (left, 3.42 +/- 2.36 vs 1.14 +/- 0.88, P > 0.03; right, 3.08 +/- 1.77 vs 1.20 +/- 0.93, P < 0.02). Metronome breathing did not significantly alter the CV% for SBP-HF, SBP-LF, and SBP-LF/HF. Metronome breathing increased parasympathetic activity, as evidenced by augmented HF power in the ECG and SBP data. The variability (CV%) of ECG-determined ANS measurements was significantly reduced with paced breathing at 12 breaths/min, but no significant reductions were observed for the SBP-determined ANS measurements. These findings indicate that ECG data are more sensitive than SBP data for future clinical trials.

Cardiac beta-adrenergic receptors and coronary hemodynamics in the conscious dog during hypoxic hypoxia.

NASA Technical Reports Server (NTRS)

Erickson, H. H.; Stone, H. L.

1972-01-01

The mechanisms by which acute hypoxia (10% and 5% oxygen) mediates changes in coronary blood flow and cardiac function were investigated in the conscious dog. When the dogs breathed hypoxic gas mixtures through a tracheostomy, both arterial and coronary sinus oxygen tensions were significantly decreased. With 5% oxygen, there were significant increases in heart rate (25%), maximum left ventricular dP/dt (39%), left circumflex coronary artery blood flow (163%), and left ventricular oxygen consumption (52%), which were attenuated by beta-adrenergic blockage with propranolol. When electrical pacing was used to keep the ventricular rate constant during hypoxia, there was no significant difference in coronary blood flow before and after beta blockade. Beta-adrenergic receptor activity in the myocardium participates in the integrated response to hypoxia although it may not cause active vasodilation of the coronary vessels.

Changes in mitral annular and left ventricular dimensions and left ventricular pressure-volume relations after off-pump treatment of mitral regurgitation with the Coapsys device.

PubMed

Fukamachi, Kiyotaka; Popović, Zoran B; Inoue, Masahiro; Doi, Kazuyoshi; Schenk, Soren; Ootaki, Yoshio; Kopcak, Michael W; McCarthy, Patrick M

2004-03-01

The objective of this study was to evaluate the changes in mitral annular and left ventricular dimensions and left ventricular pressure-volume relations produced by the Myocor Coapsys device that has been developed to treat functional mitral regurgitation (MR) off-pump. The Coapsys device, which consists of anterior and posterior epicardial pads connected by a sub-valvular chord, was implanted in seven dogs with functional MR resulting from pacing induced cardiomyopathy. The Coapsys device was then sized by drawing the posterior leaflet and annulus toward the anterior leaflet. During sizing, MR grade was assessed using color flow Doppler echocardiography. Final device size was selected when MR was eliminated or minimized. Following implantation, heart failure was maintained by continued pacing for a period of 8 weeks. Mitral annular and left ventricular dimensions and left ventricular pressure-volume relations were evaluated by two-dimensional echocardiography and a conductance catheter, respectively, at pre-sizing, post-sizing, and after 8 weeks. All implants were performed on beating hearts without cardiopulmonary bypass. Mean MR grade was reduced from 2.9+/-0.7 at pre-sizing to 0.7+/-0.8 at post-sizing (P<0.001), and was maintained at 0.8+/-0.8 after 8 weeks (P<0.01). The septal-lateral dimensions were significantly reduced at both mitral annular level [2.4+/-0.2 cm at pre-sizing, 1.5+/-0.3 cm at post-sizing (P<0.001) and 1.8+/-0.3 cm after 8 weeks (P<0.05)] and mid-papillary level [4.1+/-0.4 cm at pre-sizing, 2.4+/-0.2 cm at post-sizing (P<0.001) and 3.3+/-0.4 cm after 8 weeks (P<0.001)]. The end-systolic pressure-volume relation shifted leftward at post-sizing with a significantly steeper slope (P=0.03). There was a significant (P=0.03) leftward shift of the end-diastolic pressure-volume relation at post-sizing. After 8 weeks, these changes in pressure-volume relations tended to return to pre-sizing relations. The Coapsys device significantly reduced MR by treating both the mitral annular dilatation and the papillary muscle displacement. Despite these significant dimensional changes, the Coapsys device did not negatively affect the left ventricular pressure-volume relations.

[Non-pharmacologic therapy of hypertrophic obstructive cardiomyopathy--results of therapy based on percutaneous transluminal septal myocardial ablation compared with results of dual-chamber cardiac pacing].

PubMed

Krejcí, J; Groch, L; Meluzín, J; Vykypel, T; Halámek, J; Vitovec, J

2006-04-01

Percutaneous transluminal septal myocardial ablation (PTSMA) and pacemaker (PM) therapy with apical preexcitation are therapeutic options for hypertrophic obstructive cardiomyopathy (HOCM) patients with symptoms despite pharmacological therapy. evaluation and comparison of treatment results of PTSMA and PM implantation. 22 HOCM patients (NYHA class III and IV) with left ventricle outflow tract gradient (LVOTG) at rest more than 30 mm Hg. In group A were evaluated 11 patients treated by PTSMA. Left ventricle outflow tract gradient (LVOTG) was 90.5 +/- 16.0 mm Hg, NYHA class 3.1 +/- 0.2. Group B included 11 patients treated by dual chamber PM implantation, LVOTG in this group was 105 +/- 48 mm Hg, NYHA class 3.0 +/- 0.4. NYHA class in the group A decreased after treatment to 1.8 +/- 0.6 (p < 0.01), LVOTG to 24 +/- 12 mm Hg (p < 0.001). There was observed significant decrease in grade of systolic anterior motion (SAM), interventricular septum (IVS) thickness and left atrium (LA) size. Left ventricle end systolic diameter (LV SD) and left ventricle end diastolic diameter (LV DD) increased during follow-up. Decrease of NYHA class in the group B was to 2.1 +/- 0.6 (p < 0.001), LVOTG to 25.5 +/- 21.0 mm Hg (p < 0.001). Changes of other parameters in the group B were not significant, except decrease of SAM. Comparison of both groups: NYHA class change PTSMA/PM: 1.3 +/- 0.6/0.9 +/- 0.4 (p < 0.05), LVOTG change PTSMA/PM: -66 +/- 20/-79 +/- 46 mm Hg (p = n.s.). LV SD assessment comparison of LV SD change PTSMA/PM: 5 +/- 5/1 +/- 5 mm (p < 0.05). LA assessment - comparison of LA change PTSMA/PM: 5 +/- 5/-1 +/- 4 mm (p < 0.05). Other changes were not significant. Both therapeutic approaches - PTSMA and PM implantation - resulted in significant improvement of functional capacity assessed by NYHA classification. Decrease of LVOTG was also significant and was similar in both groups, NYHA class improvement as well as LA size decrease and LV DS increase were more expressed in PTSMA group.

Does permanent atrial fibrillation modify response to cardiac resynchronization therapy in heart failure patients?

PubMed

Abreu, Ana; Oliveira, Mário; Silva Cunha, Pedro; Santa Clara, Helena; Portugal, Guilherme; Gonçalves Rodrigues, Inês; Santos, Vanessa; Morais, Luís; Selas, Mafalda; Soares, Rui; Branco, Luísa; Ferreira, Rui; Mota Carmo, Miguel

2017-10-01

The benefits of cardiac resynchronization therapy (CRT) documented in heart failure (HF) may be influenced by atrial fibrillation (AF). We aimed to compare CRT response in patients in AF and in sinus rhythm (SR). We prospectively studied 101 HF patients treated by CRT. Rates of clinical, echocardiographic and functional response, baseline NYHA class and variation, left ventricular ejection fraction, volumes and mass, atrial volumes, cardiopulmonary exercise test (CPET) duration (CPET dur), peak oxygen consumption (VO 2 max) and ventilatory efficiency (VE/VCO 2 slope) were compared between AF and SR patients, before and at three and six months after implantation of a CRT device. All patients achieved ≥95% biventricular pacing, and 5.7% underwent atrioventricular junction ablation. Patients were divided into AF (n=35) and SR (n=66) groups; AF patients were older, with larger atrial volumes and lower CPET dur and VO 2 max before CRT. The percentages of clinical and echocardiographic responders were similar in the two groups, but there were more functional responders in the AF group (71% vs. 39% in SR patients; p=0.012). In SR patients, left atrial volume and left ventricular mass were significantly reduced (p=0.015 and p=0.021, respectively), whereas in AF patients, CPET dur (p=0.003) and VO 2 max (p=0.001; 0.083 age-adjusted) showed larger increases. Clinical and echocardiographic response rates were similar in SR and AF patients, with a better functional response in AF. Improvement in left ventricular function and volumes occurred in both groups, but left ventricular mass reduction and left atrial reverse remodeling were seen exclusively in SR patients (ClinicalTrials.gov identifier: NCT02413151; FCT code: PTDC/DES/120249/2010). Copyright © 2017 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

Ventricular stimulus site influences dynamic dispersion of repolarization in the intact human heart

PubMed Central

Orini, Michele; Simon, Ron B.; Providência, Rui; Khan, Fakhar Z.; Segal, Oliver R.; Babu, Girish G.; Bradley, Richard; Rowland, Edward; Ahsan, Syed; Chow, Anthony W.; Lowe, Martin D.; Taggart, Peter

2016-01-01

The spatial variation in restitution properties in relation to varying stimulus site is poorly defined. This study aimed to investigate the effect of varying stimulus site on apicobasal and transmural activation time (AT), action potential duration (APD) and repolarization time (RT) during restitution studies in the intact human heart. Ten patients with structurally normal hearts, undergoing clinical electrophysiology studies, were enrolled. Decapolar catheters were placed apex to base in the endocardial right ventricle (RVendo) and left ventricle (LVendo), and an LV branch of the coronary sinus (LVepi) for transmural recording. S1–S2 restitution protocols were performed pacing RVendo apex, LVendo base, and LVepi base. Overall, 725 restitution curves were analyzed, 74% of slopes had a maximum slope of activation recovery interval (ARI) restitution (Smax) > 1 (P < 0.001); mean Smax = 1.76. APD was shorter in the LVepi compared with LVendo, regardless of pacing site (30-ms difference during RVendo pacing, 25-ms during LVendo, and 48-ms during LVepi; 50th quantile, P < 0.01). Basal LVepi pacing resulted in a significant transmural gradient of RT (77 ms, 50th quantile: P < 0.01), due to loss of negative transmural AT-APD coupling (mean slope 0.63 ± 0.3). No significant transmural gradient in RT was demonstrated during endocardial RV or LV pacing, with preserved negative transmural AT-APD coupling (mean slope −1.36 ± 1.9 and −0.71 ± 0.4, respectively). Steep ARI restitution slopes predominate in the normal ventricle and dynamic ARI; RT gradients exist that are modulated by the site of activation. Epicardial stimulation to initiate ventricular activation promotes significant transmural gradients of repolarization that could be proarrhythmic. PMID:27371682

Multipolar pacing by cardiac resynchronization therapy with a defibrillators treatment in type 2 diabetes mellitus failing heart patients: impact on responders rate, and clinical outcomes.

PubMed

Sardu, Celestino; Barbieri, Michelangela; Santamaria, Matteo; Giordano, Valerio; Sacra, Cosimo; Paolisso, Pasquale; Spirito, Alessandro; Marfella, Raffaele; Paolisso, Giuseppe; Rizzo, Maria Rosaria

2017-06-09

Type 2 diabetes mellitus (T2DM) is a multi factorial disease, affecting clinical outcomes in failing heart patients treated by cardiac resynchronization therapy with a defibrillator (CRT-d). One hundred and ninety-five T2DM patients received a CRT-d treatment. Randomly the study population received a CRT-d via multipolar left ventricle (LV) lead pacing (n 99, multipolar group), vs a CRT-d via bipolar LV pacing (n 96, bipolar group). These patients were followed by clinical, and instrumental assessment, and telemetric device control at follow up. In this study we evaluated, in a population of failing heart T2DM patients, cardiac deaths, all cause deaths, arrhythmic events, CRT-d responders rate, hospitalizations for HF worsening, phrenic nerve stimulation (PNS), and LV catheter dislodgment events (and re-intervention for LV catheter re-positioning), comparing multipolar CRT-d vs bipolar CRT-d group of patients at follow up. At follow up there was a statistical significant difference about atrial arrhythmic events [7 (7%) vs 16 (16.7%), p value 0.019], hospitalizations for HF worsening [15 (15.2% vs 24 (25%), p value 0.046], LV catheter dislodgments [1 (1%) vs 9 (9.4%), p value 0018], PNS [5 (5%) vs 18 (18.7%), p value 0.007], and LV re-positioning [1 (1%) vs 9 (9.4%), p value 0.018], comparing multipolar CRT-d vs bipolar CRT-d group of patients. Multipolar pacing was an independent predictor of all these events. CRT-d pacing via multipolar LV lead vs bipolar LV lead may reduce arrhythmic burden, hospitalization rate, PNS, LV catheters dislodgments, and re-interventions in T2DM failing heart patients. Clinical trial number NCT03095196.

Electrocardiograms with pacemakers: accuracy of computer reading.

PubMed

Guglin, Maya E; Datwani, Neeta

2007-04-01

We analyzed the accuracy with which a computer algorithm reads electrocardiograms (ECGs) with electronic pacemakers (PMs). Electrocardiograms were screened for the presence of electronic pacing spikes. Computer-derived interpretations were compared with cardiologists' readings. Computer-drawn interpretations required revision by cardiologists in 61.3% of cases. In 18.4% of cases, the ECG reading algorithm failed to recognize the presence of a PM. The misinterpretation of paced beats as intrinsic beats led to multiple secondary errors, including myocardial infarctions in varying localization. The most common error in computer reading was the failure to identify an underlying rhythm. This error caused frequent misidentification of the PM type, especially when the presence of normal sinus rhythm was not recognized in a tracing with a DDD PM tracking the atrial activity. The increasing number of pacing devices, and the resulting number of ECGs with pacing spikes, mandates the refining of ECG reading algorithms. Improvement is especially needed in the recognition of the underlying rhythm, pacing spikes, and mode of pacing.

Recommendations for pacemaker implantation for the treatment of atrial tachyarrhythmias and resynchronisation therapy for heart failure

PubMed Central

van Hemel, N.M.; Dijkman, B.; de Voogt, W.G.; Beukema, W.P.; Bosker, H.A.; de Cock, C.C.; Jordaens, L.J.L.M.; van Gelder, I.C.; van Gelder, L.M.; van Mechelen, R.; Ruiter, J.H.; Sedney, M.I.; Slegers, L.C.

2004-01-01

Today, new pacing algorithms and stimulation methods for the prevention and interruption of atrial tachyarrhythmias can be applied on patients who need bradycardia pacing for conventional reasons. In addition, biventricular pacing as additive treatment for patients with severe congestive heart failure due to ventricular systolic dysfunction and prolonged intraventricular conduction has shown to improve symptoms and reduce hospital admissions. These new pacing technologies and the optimising of the pacing programmes are complex, expensive and time-consuming. Based on many clinical studies the indications for these devices are beginning to emerge. To support the cardiologist's decision-making and to prevent waste of effort and resources, the 'ad hoc committee' has provided preliminary recommendations for implantable devices to treat atrial tachyarrhythmias and to extend the treatment of congestive heart failure respectively. PMID:25696255

Pacing and Self-regulation: Important Skills for Talent Development in Endurance Sports.

PubMed

Elferink-Gemser, Marije T; Hettinga, Florentina J

2017-07-01

Pacing has been characterized as a multifaceted goal-directed process of decision making in which athletes need to decide how and when to invest their energy during the race, a process essential for optimal performance. Both physiological and psychological characteristics associated with adequate pacing and performance are known to develop with age. Consequently, the multifaceted skill of pacing might be under construction throughout adolescence, as well. Therefore, the authors propose that the complex skill of pacing is a potential important performance characteristic for talented youth athletes that needs to be developed throughout adolescence. To explore whether pacing is a marker for talent and how talented athletes develop this skill in middle-distance and endurance sports, they aim to bring together literature on pacing and literature on talent development and self-regulation of learning. Subsequently, by applying the cyclical process of self-regulation to pacing, they propose a practical model for the development of performance in endurance sports in youth athletes. Not only is self-regulation essential throughout the process of reaching the long-term goal of athletic excellence, but it also seems crucial for the development of pacing skills within a race and the development of a refined performance template based on previous experiences. Coaches and trainers are advised to incorporate pacing as a performance characteristic in their talent-development programs by stimulating their athletes to reflect, plan, monitor, and evaluate their races on a regular basis to build performance templates and, as such, improve their performance.

42 CFR 460.140 - Additional quality assessment activities.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Additional quality assessment activities. 460.140... FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.140 Additional quality assessment activities. A PACE organization must meet external quality assessment and reporting requirements...

Work and Leaving Home: The Experience of England and Wales, 1850-1920. Working Paper.

ERIC Educational Resources Information Center

Schurer, K.

Data from the 1811 and 1851 census in England and Wales as well as other data from those countries in 1891 and 1921 were analyzed to investigate individuals' timing and extent of departure from the parental home. The authors found the following: (1) there was a gradual increase in the ages at which children left the parental home; (2) the pace of…

Mitral annulus size links ventricular dilatation to functional mitral regurgitation.

PubMed

Popović, Zoran B; Martin, Maureen; Fukamachi, Kiyotaka; Inoue, Masahiro; Kwan, Jun; Doi, Kazuyoshi; Qin, Jian Xin; Shiota, Takahiro; Garcia, Mario J; McCarthy, Patrick M; Thomas, James D

2005-09-01

We compared the impact of annulus size and valve deformation (tethering) on mitral regurgitation in the animal dilated cardiomyopathy model, and assessed if acute left ventricular volume changes affect mitral annulus dimensions. We performed 3-dimensional echocardiography in 30 open-chest dogs with pacing-induced cardiomyopathy. Mitral annulus area was calculated from its two orthogonal diameters, whereas valve tethering was quantified by valve tenting area measurement. Mitral valve regurgitant volume showed the highest correlation with annulus area (r = 0.64, P < .001), left atrial volume (r = 0.40, P < .01), and left ventricular end-diastolic volume (r = 0.37, P < .01). Regurgitant volume showed poorer correlation with valve tethering in both septolateral and intercommissural planes (r = 0.35 and r = 0.31, P < .05 for both). Annulus dimensions correlated with acute changes of left ventricular end-diastolic volume (r = 0.68, P = .002). Mitral annulus dilation is the strongest predictor of functional mitral regurgitation in this animal dilated cardiomyopathy model.

Survival After Rate-Responsive Programming in Patients With Cardiac Resynchronization Therapy-Defibrillator Implants Is Associated With a Novel Parameter: The Heart Rate Score.

PubMed

Olshansky, Brian; Richards, Mark; Sharma, Arjun; Wold, Nicholas; Jones, Paul; Perschbacher, David; Wilkoff, Bruce L

2016-08-01

Rate-responsive pacing (DDDR) versus nonrate-responsive pacing (DDD) has shown no survival benefit for patients undergoing cardiac resynchronization therapy defibrillator (CRT-D) implants. The heart rate score (HRSc), an indicator of heart rate variation, may predict survival. We hypothesized that high-risk HRSc CRT-D patients will have improved survival with DDDR versus DDD alone. All CRT-D patients in LATITUDE remote monitoring (2006-2011), programmed DDD, had HRSc calculated at first data upload after implant (median 1.4 months). Patients subsequently reprogrammed to DDDR 7.6 median months later were compared with a propensity-matched DDD group and followed for 21.4 median months by remote monitoring. Data were adjusted for age, sex, lower rate limit, percent atrial pacing, percent biventricular pacing, and implant year. The social security death index was used to identify deaths. Remote monitoring provided programming and histogram data. DDDR programming in CRT-D patients was associated with improved survival (adjusted hazard ratio =0.77; P<0.001). However, only those with baseline HRSc ≥70% (2308/6164) had improved HRSc with DDDR (from 88±9% to 78±15%; P<0.001) and improved survival (hazard ratio =0.74; P<0.001). Patients with a high baseline HRSc and significant improvement over time were more likely to survive (hazard ratio =0.63; P=0.006). For patients with HRSc <70%, DDDR reprogramming increased the HRSc from 46±11% to 50±15% (P<0.001); survival did not change. The HRSc did not change with DDD pacing over time. In CRT-D patients with HRSc ≥70%, DDDR reprogramming improved the HRSc and was associated with survival. Patients with lower HRSc had no change in survival with DDDR programming. © 2016 American Heart Association, Inc.

Synchronized personalized music audio-playlists to improve adherence to physical activity among patients participating in a structured exercise program: a proof-of-principle feasibility study.

PubMed

Alter, David A; O'Sullivan, Mary; Oh, Paul I; Redelmeier, Donald A; Marzolini, Susan; Liu, Richard; Forhan, Mary; Silver, Michael; Goodman, Jack M; Bartel, Lee R

2015-01-01

Preference-based tempo-pace synchronized music has been shown to reduce perceived physical activity exertion and improve exercise performance. The extent to which such strategies can improve adherence to physical activity remains unknown. The objective of the study is to explore the feasibility and efficacy of tempo-pace synchronized preference-based music audio-playlists on adherence to physical activity among cardiovascular disease patients participating in a cardiac rehabilitation. Thirty-four cardiac rehabilitation patients were randomly allocated to one of two strategies: (1) no music usual-care control and (2) tempo-pace synchronized audio-devices with personalized music playlists + usual-care. All songs uploaded onto audio-playlist devices took into account patient personal music genre and artist preferences. However, actual song selection was restricted to music whose tempos approximated patients' prescribed exercise walking/running pace (steps per minute) to achieve tempo-pace synchrony. Patients allocated to audio-music playlists underwent further randomization in which half of the patients received songs that were sonically enhanced with rhythmic auditory stimulation (RAS) to accentuate tempo-pace synchrony, whereas the other half did not. RAS was achieved through blinded rhythmic sonic-enhancements undertaken manually to songs within individuals' music playlists. The primary outcome consisted of the weekly volume of physical activity undertaken over 3 months as determined by tri-axial accelerometers. Statistical methods employed an intention to treat and repeated-measures design. Patients randomized to personalized audio-playlists with tempo-pace synchrony achieved higher weekly volumes of physical activity than did their non-music usual-care comparators (475.6 min vs. 370.2 min, P  < 0.001). Improvements in weekly physical activity volumes among audio-playlist recipients were driven by those randomized to the RAS group which attained weekly exercise volumes that were nearly twofold greater than either of the two other groups (average weekly minutes of physical activity of 631.3 min vs. 320 min vs. 370.2 min, personalized audio-playlists with RAS vs. personalized audio-playlists without RAS vs. non-music usual-care controls, respectively, P  < 0.001). Patients randomized to music with RAS utilized their audio-playlist devices more frequently than did non-RAS music counterparts ( P  < 0.001). The use of tempo-pace synchronized preference-based audio-playlists was feasibly implemented into a structured exercise program and efficacious in improving adherence to physical activity beyond the evidence-based non-music usual standard of care. Larger clinical trials are required to validate these findings. ClinicalTrials.gov ID (NCT01752595).

A Low-Cost Simulation Model for R-Wave Synchronized Atrial Pacing in Pediatric Patients with Postoperative Junctional Ectopic Tachycardia

PubMed Central

Michel, Miriam; Egender, Friedemann; Heßling, Vera; Dähnert, Ingo; Gebauer, Roman

2016-01-01

Background Postoperative junctional ectopic tachycardia (JET) occurs frequently after pediatric cardiac surgery. R-wave synchronized atrial (AVT) pacing is used to re-establish atrioventricular synchrony. AVT pacing is complex, with technical pitfalls. We sought to establish and to test a low-cost simulation model suitable for training and analysis in AVT pacing. Methods A simulation model was developed based on a JET simulator, a simulation doll, a cardiac monitor, and a pacemaker. A computer program simulated electrocardiograms. Ten experienced pediatric cardiologists tested the model. Their performance was analyzed using a testing protocol with 10 working steps. Results Four testers found the simulation model realistic; 6 found it very realistic. Nine claimed that the trial had improved their skills. All testers considered the model useful in teaching AVT pacing. The simulation test identified 5 working steps in which major mistakes in performance test may impede safe and effective AVT pacing and thus permitted specific training. The components of the model (exclusive monitor and pacemaker) cost less than $50. Assembly and training-session expenses were trivial. Conclusions A realistic, low-cost simulation model of AVT pacing is described. The model is suitable for teaching and analyzing AVT pacing technique. PMID:26943363

Adverse effects of permanent atrial fibrillation on heart failure in patients with preserved left ventricular function and chronic right apical pacing for complete heart block.

PubMed

Lampe, Brigitte; Hammerstingl, Christoph; Schwab, Jörg Otto; Mellert, Fritz; Stoffel-Wagner, Birgit; Grigull, Andreas; Fimmers, Rolf; Maisch, Bernhard; Nickenig, Georg; Lewalter, Thorsten; Yang, Alexander

2012-10-01

The impact of atrial fibrillation (AF) on heart failure (HF) was evaluated in patients with preserved left ventricular (LV) function and long-term right ventricular (RV) pacing for complete heart block. Clinical, echocardiographic, and laboratory parameters of HF were assessed in 35 patients with established AF who had undergone ablation of the atrioventricular node and pacemaker implantation (Group A) and 31 patients who received dual-chamber pacing for spontaneous complete heart block (Group B). During a follow-up period of 12.7 ± 7.5 years, New York Heart Association (NYHA) functional class increased from 1.3 ± 0.5 to 2.1 ± 0.6 (p < 0.0001) in Group A, and from 1.3 ± 0.4 to 1.6 ± 0.7 (p < 0.01) in Group B. Left ventricular ejection fraction (LVEF) decreased from 59.7 ± 5.1 to 53.0 ± 8.2 (p < 0.0001) in Group A, but remained stable (58.6 ± 4.2 vs. 56.9 ± 7.0 %, p = 0,21) in Group B. At the end of follow-up, markers of LV function were moderately depressed in Group A compared with those in Group B: NYHA class 2.1 ± 0.6 versus 1.6 ± 0.7, p = 0.001; LVEF 53.0 ± 8.2 versus 56.9 ± 7.0 %, p < 0.05; LV diastolic diameter 53.6 ± 5.8 mm versus 50.7 ± 4.9 mm, p < 0.05; N-terminal pro-brain natriuretic peptide (NT-proBNP) 1116.8 ± 883.9 versus 622.9 ± 1059.4 pg/ml, p < 0.05. Progression of paroxysmal AF to permanent AF during follow-up was common, while new onset of AF was rare. Permanent AF was an independent predictor of declining LVEF >10 %, increasing NYHA class ≥1, and NT-proBNP levels >1,000 pg/ml. Permanent AF was associated with adverse effects on LV function and symptoms of HF in patients with long-term RV pacing for complete heart block, and appears to play an important role in the development of HF in this specific patient cohort.

Restructuring VA ambulatory care and medical education: the PACE model of primary care.

PubMed

Cope, D W; Sherman, S; Robbins, A S

1996-07-01

The Veterans Health Administration (VHA) Western Region and associated medical schools formulated a set of recommendations for an improved ambulatory health care delivery system during a 1988 strategic planning conference. As a result, the Department of Veterans Affairs (VA) Medical Center in Sepulveda, California, initiated the Pilot (now Primary) Ambulatory Care and Education (PACE) program in 1990 to implement and evaluate a model program. The PACE program represents a significant departure from traditional VA and non-VA academic medical center care, shifting the focus of care from the inpatient to the outpatient setting. From its inception, the PACE program has used an interdisciplinary team approach with three independent global care firms. Each firm is interdisciplinary in composition, with a matrix management structure that expands role function and empowers team members. Emphasis is on managed primary care, stressing a biopsychosocial approach and cost-effective comprehensive care emphasizing prevention and health maintenance. Information management is provided through a network of personal computers that serve as a front end to the VHA Decentralized Hospital Computer Program (DHCP) mainframe. In addition to providing comprehensive and cost-effective care, the PACE program educates trainees in all health care disciplines, conducts research, and disseminates information about important procedures and outcomes. Undergraduate and graduate trainees from 11 health care disciplines rotate through the PACE program to learn an integrated approach to managed ambulatory care delivery. All trainees are involved in a problem-based approach to learning that emphasizes shared training experiences among health care disciplines. This paper describes the transitional phases of the PACE program (strategic planning, reorganization, and quality improvement) that are relevant for other institutions that are shifting to training programs emphasizing primary and ambulatory care.

Further optimization of a hybrid united-atom and coarse-grained force field for folding simulations: Improved backbone hydration and interactions between charged side chains

PubMed Central

Han, Wei; Schulten, Klaus

2012-01-01

PACE, a hybrid force field which couples united-atom protein models with coarse-grained (CG) solvent, has been further optimized, aiming to improve itse ciency for folding simulations. Backbone hydration parameters have been re-optimized based on hydration free energies of polyalanyl peptides through atomistic simulations. Also, atomistic partial charges from all-atom force fields were combined with PACE in order to provide a more realistic description of interactions between charged groups. Using replica exchange molecular dynamics (REMD), ab initio folding using the new PACE has been achieved for seven small proteins (16 – 23 residues) with different structural motifs. Experimental data about folded states, such as their stability at room temperature, melting point and NMR NOE constraints, were also well reproduced. Moreover, a systematic comparison of folding kinetics at room temperature has been made with experiments, through standard MD simulations, showing that the new PACE may speed up the actual folding kinetics 5-10 times. Together with the computational speedup benefited from coarse-graining, the force field provides opportunities to study folding mechanisms. In particular, we used the new PACE to fold a 73-residue protein, 3D, in multiple 10 – 30 μs simulations, to its native states (Cα RMSD ~ 0.34 nm). Our results suggest the potential applicability of the new PACE for the study of folding and dynamics of proteins. PMID:23204949

Clinical characteristics associated with pacing-induced cardiac dysfunction: a high incidence of undiagnosed cardiac sarcoidosis before permanent pacemaker implantation.

PubMed

Wakabayashi, Yasushi; Mitsuhashi, Takeshi; Akashi, Naoyuki; Hayashi, Takekuni; Umemoto, Tomio; Sugawara, Yoshitaka; Fujita, Hideo; Momomura, Shin-Ichi

2018-06-21

Previous studies suggested that right ventricular pacing was associated with pacing-induced cardiac dysfunction (PICD). The purpose of this study was to investigate the clinical characteristics including the incidence of undiagnosed cardiac sarcoidosis (CS) in patients with atrioventricular block (AVB) who manifest PICD. We retrospectively investigated consecutive patients with permanent pacemaker (PPM) undergoing a first-generator replacement surgery with a new PPM or an upgrade procedure to a cardiac resynchronization therapy (CRT) device between December 1, 2011 and June 30, 2017. Patients with AVB showing normal echocardiographic findings before PPM implantation were included and divided into 2 groups: patients with post-PPM left ventricular ejection fraction (LVEF) < 40% and/or undergoing an upgrade procedure to CRT (PICD group) and patients with post-PPM LVEF ≥ 40% who underwent replacement surgery with a new PPM (no-PICD group). There were 15 and 41 patients in the PICD and no-PICD groups, respectively. A wider-paced QRS duration just after the PPM implantation and/or lower pre-PPM LVEF was observed in the PICD group. Furthermore, 46.7% of the PICD patients (7/15) satisfied the diagnostic criteria for CS according to the guideline of the Japanese Circulation Society, although no patients fulfilled these criteria before PPM implantation. In conclusion, a high incidence of CS was observed in patients with AVB who had PICD. However, none of these patients was diagnosed with CS before PPM implantation.

Usefulness and limitation of dobutamine stress echocardiography to predict acute response to cardiac resynchronization therapy.

PubMed

Sénéchal, Mario; Lancellotti, Patrizio; Garceau, Patrick; Champagne, Jean; Dubois, Michelle; Magne, Julien; Blier, Louis; Molin, Frank; Philippon, François; Dumesnil, Jean G; Pierard, Luc; O'Hara, Gilles

2010-01-01

It has been hypothesized that a long-term response to cardiac resynchronization therapy (CRT) could correlate with myocardial viability in patients with left ventricular (LV) dysfunction. Contractile reserve and viability in the region of the pacing lead have not been investigated in regard to acute response after CRT. Fifty-one consecutive patients with advanced heart failure, LV ejection fraction 120 ms, and intraventricular asynchronism >or= 50 ms were prospectively included. The week before CRT implantation, the presence of viability was evaluated using dobutamine stress echocardiography. Acute responders were defined as a >or=15% increase in LV stroke volume. The average of viable segments was 5.8 +/- 1.9 in responders and 3.9 +/- 3 in nonresponders (P = 0.03). Viability in the region of the pacing lead had an excellent sensitivity (96%), but a low specificity (56%) to predict acute response to CRT. Mitral regurgitation (MR) was reduced in 21 patients (84%) with acute response. The presence of MR was a poor predictor of response (sensibility 93% and specificity 17%). However, combining the presence of MR and viability in the region of the pacing lead yields a sensibility (89%) and a specificity (70%) to predict acute response to CRT. Myocardial viability is an important factor influencing acute hemodynamic response to CRT. In acute responders, significant MR reduction is frequent. The combined presence of MR and viability in the region of the pacing lead predicts acute response to CRT with the best accuracy.

Towards PACE Atmospheric Correction, Aerosol and Cloud Products: Making Use of Expanded Spectral, Angular and Polarimetric Information.

NASA Astrophysics Data System (ADS)

Remer, L. A.; Boss, E.; Ahmad, Z.; Cairns, B.; Chowdhary, J.; Coddington, O.; Davis, A. B.; Dierssen, H. M.; Diner, D. J.; Franz, B. A.; Frouin, R.; Gao, B. C.; Garay, M. J.; Heidinger, A.; Ibrahim, A.; Kalashnikova, O. V.; Knobelspiesse, K. D.; Levy, R. C.; Omar, A. H.; Meyer, K.; Platnick, S. E.; Seidel, F. C.; van Diedenhoven, B.; Werdell, J.; Xu, F.; Zhai, P.; Zhang, Z.

2017-12-01

NASA's Science Team for the Plankton, Aerosol, Clouds, ocean Ecosystem (PACE) mission is concluding three years of study exploring the science potential of expanded spectral, angular and polarization capability for space-based retrievals of water leaving radiance, aerosols and clouds. The work anticipates future development of retrievals to be applied to the PACE Ocean Color Instrument (OCI) and/or possibly a PACE Multi-Angle Polarimeter (MAP). In this presentation we will report on the Science Team's accomplishments associated with the atmosphere (significant efforts are also directed by the ST towards the ocean). Included in the presentation will be sensitivity studies that explore new OCI capabilities for aerosol and cloud layer height, aerosol absorption characterization, cloud property retrievals, and how we intend to move from heritage atmospheric correction algorithms to make use of and adjust to OCI's hyperspectral and UV wavelengths. We will then address how capabilities will improve with the PACE MAP, how these capabilities from both OCI and MAP correspond to specific societal benefits from the PACE mission, and what is still needed to close the gaps in our understanding before the PACE mission can realize its full potential.

Development and evaluation of the feasibility and effects on staff, patients, and families of a new tool, the Psychosocial Assessment and Communication Evaluation (PACE), to improve communication and palliative care in intensive care and during clinical uncertainty.

PubMed

Higginson, Irene J; Koffman, Jonathan; Hopkins, Philip; Prentice, Wendy; Burman, Rachel; Leonard, Sara; Rumble, Caroline; Noble, Jo; Dampier, Odette; Bernal, William; Hall, Sue; Morgan, Myfanwy; Shipman, Cathy

2013-10-01

There are widespread concerns about communication and support for patients and families, especially when they face clinical uncertainty, a situation most marked in intensive care units (ICUs). Therefore, we aimed to develop and evaluate an interventional tool to improve communication and palliative care, using the ICU as an example of where this is difficult. Our design was a phase I-II study following the Medical Research Council Guidance for the Development and Evaluation of Complex Interventions and the (Methods of Researching End-of-life Care (MORECare) statement. In two ICUs, with over 1900 admissions annually, phase I modeled a new intervention comprising implementation training and an assessment tool. We conducted a literature review, qualitative interviews, and focus groups with 40 staff and 13 family members. This resulted in the new tool, the Psychosocial Assessment and Communication Evaluation (PACE). Phase II evaluated the feasibility and effects of PACE, using observation, record audit, and surveys of staff and family members. Qualitative data were analyzed using the framework approach. The statistical tests used on quantitative data were t-tests (for normally distributed characteristics), the χ2 or Fisher's exact test (for non-normally distributed characteristics) and the Mann-Whitney U-test (for experience assessments) to compare the characteristics and experience for cases with and without PACE recorded. PACE provides individualized assessments of all patients entering the ICU. It is completed within 24 to 48 hours of admission, and covers five aspects (key relationships, social details and needs, patient preferences, communication and information status, and other concerns), followed by recording of an ongoing communication evaluation. Implementation is supported by a training program with specialist palliative care. A post-implementation survey of 95 ICU staff found that 89% rated PACE assessment as very or generally useful. Of 213 family members, 165 (78%) responded to their survey, and two-thirds had PACE completed. Those for whom PACE was completed reported significantly higher satisfaction with symptom control, and the honesty and consistency of information from staff (Mann-Whitney U-test ranged from 616 to 1247, P-values ranged from 0.041 to 0.010) compared with those who did not. PACE is a feasible interventional tool that has the potential to improve communication, information consistency, and family perceptions of symptom control.

A massive open online course (MOOC) can be used to teach physiotherapy students about spinal cord injuries: a randomised trial.

PubMed

Hossain, Mohammad S; Shofiqul Islam, Md; Glinsky, Joanne V; Lowe, Rachael; Lowe, Tony; Harvey, Lisa A

2015-01-01

Does a massive open online course (MOOC) based around an online learning module about spinal cord injuries improve knowledge or confidence among physiotherapy students more than if physiotherapy students are left to work through the online learning module at their own pace. Which method of presenting the content leads to greater satisfaction among the students? Randomised controlled trial with concealed allocation and intention-to-treat analysis. Forty-eight physiotherapy students in Bangladesh. Participants randomised to the control group were instructed to work at their own pace over a 5-week period through a physiotherapy-specific online learning module available at www.elearnSCI.org. Experimental participants were enrolled in a 5-week MOOC. The MOOC involved completing the same online learning module but experimental participants' progress through the module was guided each week and they were provided with the opportunity to engage in online discussion through Facebook. The primary outcome was knowledge, and the secondary outcomes were perceived confidence to treat people with spinal cord injuries and satisfaction with the learning experience. The mean between-group difference for knowledge was 0.7 points (95% CI -1.3 to 2.6) on a 0 to 20-point scale. The equivalent results for perceived confidence and satisfaction with the learning experience were 0.4 points (95% CI -1.0 to 1.8) and 0.0 points (95% CI -1.1 to 1.2) on a 0 to 10-point scale. The MOOC was no better for students than working at their own pace through an online learning module for increasing knowledge, confidence or satisfaction. However, students in the MOOC group highlighted positive aspects of the course that were unique to their group, such as interacting with students from other countries through the MOOC Facebook group. ACTRN12614000422628. Copyright © 2014. Published by Elsevier B.V.

Right ventricular strain analysis from three-dimensional echocardiography by using temporally diffeomorphic motion estimation.

PubMed

Zhang, Zhijun; Zhu, Meihua; Ashraf, Muhammad; Broberg, Craig S; Sahn, David J; Song, Xubo

2014-12-01

Quantitative analysis of right ventricle (RV) motion is important for study of the mechanism of congenital and acquired diseases. Unlike left ventricle (LV), motion estimation of RV is more difficult because of its complex shape and thin myocardium. Although attempts of finite element models on MR images and speckle tracking on echocardiography have shown promising results on RV strain analysis, these methods can be improved since the temporal smoothness of the motion is not considered. The authors have proposed a temporally diffeomorphic motion estimation method in which a spatiotemporal transformation is estimated by optimization of a registration energy functional of the velocity field in their earlier work. The proposed motion estimation method is a fully automatic process for general image sequences. The authors apply the method by combining with a semiautomatic myocardium segmentation method to the RV strain analysis of three-dimensional (3D) echocardiographic sequences of five open-chest pigs under different steady states. The authors compare the peak two-point strains derived by their method with those estimated from the sonomicrometry, the results show that they have high correlation. The motion of the right ventricular free wall is studied by using segmental strains. The baseline sequence results show that the segmental strains in their methods are consistent with results obtained by other image modalities such as MRI. The image sequences of pacing steady states show that segments with the largest strain variation coincide with the pacing sites. The high correlation of the peak two-point strains of their method and sonomicrometry under different steady states demonstrates that their RV motion estimation has high accuracy. The closeness of the segmental strain of their method to those from MRI shows the feasibility of their method in the study of RV function by using 3D echocardiography. The strain analysis of the pacing steady states shows the potential utility of their method in study on RV diseases.

Echocardiography in patients with complications related to pacemakers and cardiac defibrillators.

PubMed

Almomani, Ahmed; Siddiqui, Khadija; Ahmad, Masood

2014-03-01

The evolving indications and uses for implantable cardiac devices have led to a significant increase in the number of implanted devices each year. Implantation of endocardial leads for permanent pacemakers and cardiac defibrillators can cause many delayed complications. Complications may be mechanical and related to the interaction of the device leads with the valves and endomyocardium, e.g., perforation, infection, and thrombosis, or due to the electrical pacing of the myocardium and conduction abnormalities, e.g., left ventricular dyssynchrony. Tricuspid regurgitation, another delayed complication in these patients, may be secondary to both mechanical and pacing effects of the device leads. Echocardiography plays an important role in the diagnosis of these device-related complications. Both two-dimensional transthoracic echocardiography and transesophageal echocardiography provide useful diagnostic information. Real time three-dimensional echocardiography is a novel technique that can further enhance the detection of lead-related complications. © 2013, Wiley Periodicals, Inc.

Application of PACE Principles for Population Health Management of Frail Older Adults.

PubMed

Stefanacci, Richard G; Reich, Shelley; Casiano, Alex

2015-10-01

To determine which practices would have the most impact on reducing hospital and emergency department admissions and nursing home placement among older adults with multiple comorbid conditions, a literature search and survey were conducted to identify and prioritize comprehensive care principles as practiced in the Program of All-inclusive Care for the Elderly (PACE). PACE medical directors and members of the PACE interdisciplinary team (IDT) were surveyed to gain their insights on the most impactful practices, which were identified as: End-of-Life Management, Caregiver Support, Management of Red Flags, Medication Management, Participant and Caregiver Health Care System Literacy, and Care Coordination. In addition, this research evaluated measures that could be used to assess an organization's level of success with regard to each of the 6 PACE practices identified. The results reported in this article, found through a survey with PACE medical directors and IDT members concerning effective interventions, can be viewed as strategies to improve care for older adults, enabling them to maintain their independence in the community, avoid the expense of facility-based care, and enhance their quality of life.

[Clinical experiences with four newly developed, surface modified stimulation electrodes].

PubMed

Winter, U J; Fritsch, J; Liebing, J; Höpp, H W; Hilger, H H

1993-05-01

Newly developed pacing electrodes with so-called porous surfaces promise a significantly improved post-operative pacing and sensing threshold. We therefore investigated four newly developed leads (ELA-PMCF-860 n = 10; Biotronik-60/4-DNP n = 10, CPI-4010 n = 10, Intermedics-421-03-Biopore n = 6) connected to two different pacing devices (Intermedics NOVA II, Medtronic PASYS) in 36 patients (18 men, 18 women, age: 69.7 +/- 9.8 years) suffering from symptomatic bradycardia. The individual electrode maturation process was investigated by means of repeated measurements of pacing threshold, electrode impedance in acute, subacute, and chronic phase, as well as energy consumption and sensing behavior in the chronic phase. However, with the exception of the 4010, the investigated leads showed largely varying values of the pacing threshold with individual peaks occurring from the second up to the 13th week. All leads had nearly similar chronic pacing thresholds (PMCF 0.13 +/- 0.07; DNP 0.25 +/- 0.18; Biopore 0.15 +/- 0.05; 4010 0.14 +/- 0.05 ms). Impedance measurements revealed higher, but not significantly different values for the DNP (PMCF 582 +/- 112, DNP 755 +/- 88, Biopore 650 +/- 15, 4010 718 +/- 104 Ohm). Despite differing values for pacing threshold and impedance, the energy consumption in the chronic phase during threshold-adapted, but secure stimulation (3 * impulse-width at pacing threshold) were comparable.

42 CFR 460.134 - Minimum requirements for quality assessment and performance improvement program.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Quality of life of participants. (4) Effectiveness and safety of staff-provided and contracted services... 42 Public Health 4 2012-10-01 2012-10-01 false Minimum requirements for quality assessment and... ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance...

42 CFR 460.134 - Minimum requirements for quality assessment and performance improvement program.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Quality of life of participants. (4) Effectiveness and safety of staff-provided and contracted services... 42 Public Health 4 2011-10-01 2011-10-01 false Minimum requirements for quality assessment and... ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance...

42 CFR 460.134 - Minimum requirements for quality assessment and performance improvement program.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Quality of life of participants. (4) Effectiveness and safety of staff-provided and contracted services... 42 Public Health 4 2010-10-01 2010-10-01 false Minimum requirements for quality assessment and... ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance...

42 CFR 460.134 - Minimum requirements for quality assessment and performance improvement program.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Quality of life of participants. (4) Effectiveness and safety of staff-provided and contracted services... 42 Public Health 4 2013-10-01 2013-10-01 false Minimum requirements for quality assessment and... ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance...

42 CFR 460.134 - Minimum requirements for quality assessment and performance improvement program.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Quality of life of participants. (4) Effectiveness and safety of staff-provided and contracted services... 42 Public Health 4 2014-10-01 2014-10-01 false Minimum requirements for quality assessment and... ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance...

Health Information System Simulation. Curriculum Improvement Project. Region II.

ERIC Educational Resources Information Center

Anderson, Beth H.; Lacobie, Kevin

This volume is one of three in a self-paced computer literacy course that gives allied health students a firm base of knowledge concerning computer usage in the hospital environment. It also develops skill in several applications software packages. This volume contains five self-paced modules that allow students to interact with a health…

Tools and Trends in Self-Paced Language Instruction

ERIC Educational Resources Information Center

Godwin-Jones, Robert

2007-01-01

Ever since the PLATO system of the 1960's, CALL (computer assisted language learning) has had a major focus on providing self-paced, auto-correcting exercises for language learners to practice their skills and improve their knowledge of discrete areas of language learning. The computer has been recognized from the beginning as a patient and…

Spontaneous Velocity Effect of Musical Expression on Self-Paced Walking.

PubMed

Buhmann, Jeska; Desmet, Frank; Moens, Bart; Van Dyck, Edith; Leman, Marc

2016-01-01

The expressive features of music can influence the velocity of walking. So far, studies used instructed (and intended) synchronization. But is this velocity effect still present with non-instructed (spontaneous) synchronization? To figure that out, participants were instructed to walk in their own comfort tempo on an indoor track, first in silence and then with tempo-matched music. We compared velocities of silence and music conditions. The results show that some music has an activating influence, increasing velocity and motivation, while other music has a relaxing influence, decreasing velocity and motivation. The influence of musical expression on the velocity of self-paced walking can be predicted with a regression model using only three sonic features explaining 56% of the variance. Phase-coherence between footfall and beat did not contribute to the velocity effect, due to its implied fixed pacing. The findings suggest that the velocity effect depends on vigor entrainment that influences both stride length and pacing. Our findings are relevant for preventing injuries, for gait improvement in walking rehabilitation, and for improving performance in sports activities.

Spontaneous Velocity Effect of Musical Expression on Self-Paced Walking

PubMed Central

Buhmann, Jeska; Desmet, Frank; Moens, Bart; Van Dyck, Edith; Leman, Marc

2016-01-01

The expressive features of music can influence the velocity of walking. So far, studies used instructed (and intended) synchronization. But is this velocity effect still present with non-instructed (spontaneous) synchronization? To figure that out, participants were instructed to walk in their own comfort tempo on an indoor track, first in silence and then with tempo-matched music. We compared velocities of silence and music conditions. The results show that some music has an activating influence, increasing velocity and motivation, while other music has a relaxing influence, decreasing velocity and motivation. The influence of musical expression on the velocity of self-paced walking can be predicted with a regression model using only three sonic features explaining 56% of the variance. Phase-coherence between footfall and beat did not contribute to the velocity effect, due to its implied fixed pacing. The findings suggest that the velocity effect depends on vigor entrainment that influences both stride length and pacing. Our findings are relevant for preventing injuries, for gait improvement in walking rehabilitation, and for improving performance in sports activities. PMID:27167064

Self-paced cycling performance and recovery under a hot and highly humid environment after cooling.

PubMed

Gonzales, B R; Hagin, V; Guillot, R; Placet, V; Monnier-Benoit, P; Groslambert, A

2014-02-01

This study investigated the effects of pre- and post-cooling on self-paced time-trial cycling performance and recovery of cyclists exercising under a hot and highly humid environment (29.92 °C-78.52% RH). Ten male cyclists performed a self-paced 20-min time trial test (TT20) on a cyclo-ergometer while being cooled by a cooling vest and a refrigerating headband during the warm-up and the recovery period. Heart rate, power output, perceived exertion, thermal comfort, skin and rectal temperatures were recorded. Compared to control condition (222.78 ± 47 W), a significant increase (P<0.05) in the mean power output during the TT20 (239.07 ± 45 W; +7.31%) was recorded with a significant (P<0.05) decrease in skin temperature without affecting perceived exertion, heart rate, or rectal temperature at the end of the TT20. However, pace changes occurred independently of skin or rectal temperatures variations but a significant difference (P<0.05) in the body's heat storage was observed between both conditions. This result suggests that a central programmer using body's heat storage as an input may influence self-paced time-trial performance. During the recovery period, post-cooling significantly decreased heart rate, skin and rectal temperatures, and improved significantly (P<0.05) thermal comfort. Therefore, in hot and humid environments, wearing a cooling vest and a refrigerating headband during warm-up improves self-paced performance, and appears to be an effective mean of reaching skin rest temperatures more rapidly during recovery.

Did recent world record marathon runners employ optimal pacing strategies?

PubMed

Angus, Simon D

2014-01-01

We apply statistical analysis of high frequency (1 km) split data for the most recent two world-record marathon runs: Run 1 (2:03:59, 28 September 2008) and Run 2 (2:03:38, 25 September 2011). Based on studies in the endurance cycling literature, we develop two principles to approximate 'optimal' pacing in the field marathon. By utilising GPS and weather data, we test, and then de-trend, for each athlete's field response to gradient and headwind on course, recovering standardised proxies for power-based pacing traces. The resultant traces were analysed to ascertain if either runner followed optimal pacing principles; and characterise any deviations from optimality. Whereas gradient was insignificant, headwind was a significant factor in running speed variability for both runners, with Runner 2 targeting the (optimal) parallel variation principle, whilst Runner 1 did not. After adjusting for these responses, neither runner followed the (optimal) 'even' power pacing principle, with Runner 2's macro-pacing strategy fitting a sinusoidal oscillator with exponentially expanding envelope whilst Runner 1 followed a U-shaped, quadratic form. The study suggests that: (a) better pacing strategy could provide elite marathon runners with an economical pathway to significant performance improvements at world-record level; and (b) the data and analysis herein is consistent with a complex-adaptive model of power regulation.

Right versus left atrial pacing in patients with sick sinus syndrome and paroxysmal atrial fibrillation (Riverleft study): study protocol for randomized controlled trial.

PubMed

Ramdjan, Tanwier T T K; van der Does, Lisette J M E; Knops, Paul; Res, Jan C J; de Groot, Natasja M S

2014-11-17

The incidence of sick sinus syndrome will increase due to population ageing. Consequently, this will result in an increase in the number of pacemaker implantations. The atrial lead is usually implanted in the right atrial appendage, but this position may be ineffective for prevention of atrial fibrillation. It has been suggested that pacing distally in the coronary sinus might be more successful in preventing atrial fibrillation episodes. The aim of this trial is to study the efficacy of distal coronary sinus versus right atrial appendage pacing in preventing atrial fibrillation episodes in patients with sick sinus syndrome. This study is designed as a multicenter, randomized controlled trial. Patients with sick sinus syndrome and at least one atrial fibrillation episode of 30 seconds or more in the six months before recruitment will be eligible for participation in this study.All participants will be randomized between pacing distally in the coronary sinus and right atrial appendage. Randomization is stratified for all participating centers. Conventional dual-chamber pacemakers with advanced home monitoring functionality will be implanted. The ventricular lead will be implanted in the right ventricular apex. The first three months of the 36-month follow-up period are considered as run-in time. During the pre-randomization visit and follow-up, an interview, electrocardiogram and pacemaker assessment will be performed, prescribed antiarrhythmic medication will be reviewed and patients will be asked to complete an SF-36 questionnaire. An echocardiographic examination will be conducted in the pre-randomization phase and at the end of each follow-up year. Home monitoring will be used to send daily reports in case of atrial fibrillation episodes. This randomized controlled trial is the first in which home monitoring will be used to compare atrial fibrillation recurrences between pacing in the distal coronary sinus or right atrial appendage. Home monitoring gives the opportunity to accurately detect atrial fibrillation episodes and to study characteristics of atrial fibrillation episodes. Should distal coronary sinus pacing significantly diminish atrial fibrillation recurrences, this study will redefine the preferential location of an atrial lead for preventive pacing. Current Controlled Trials ISRCTN65911661, registered on 8 July 2013.

Let's Walk Outdoors! Self-Paced Walking Outdoors Improves Future Intention to Exercise in Women With Obesity.

PubMed

Krinski, Kleverton; Machado, Daniel G S; Lirani, Luciana S; DaSilva, Sergio G; Costa, Eduardo C; Hardcastle, Sarah J; Elsangedy, Hassan M

2017-04-01

In order to examine whether environmental settings influence psychological and physiological responses of women with obesity during self-paced walking, 38 women performed two exercise sessions (treadmill and outdoors) for 30 min, where oxygen uptake, heart rate, ratings of perceived exertion, affect, attentional focus, enjoyment, and future intentions to walk were analyzed. Physiological responses were similar during both sessions. However, during outdoor exercise, participants displayed higher externally focused attention, positive affect, and lower ratings of perceived exertion, followed by greater enjoyment and future intention to participate in outdoor walking. The more externally focused attention predicted greater future intentions to participate in walking. Therefore, women with obesity self-selected an appropriate exercise intensity to improve fitness and health in both environmental settings. Also, self-paced outdoor walking presented improved psychological responses. Health care professionals should consider promoting outdoor forms of exercise to maximize psychological benefits and promote long-term adherence to a physically active lifestyle.

Walking to the Beat of Their Own Drum: How Children and Adults Meet Timing Constraints

PubMed Central

Gill, Simone V.

2015-01-01

Walking requires adapting to meet task constraints. Between 5- and 7-years old, children’s walking approximates adult walking without constraints. To examine how children and adults adapt to meet timing constraints, 57 5- to 7-year olds and 20 adults walked to slow and fast audio metronome paces. Both children and adults modified their walking. However, at the slow pace, children had more trouble matching the metronome compared to adults. The youngest children’s walking patterns deviated most from the slow metronome pace, and practice improved their performance. Five-year olds were the only group that did not display carryover effects to the metronome paces. Findings are discussed in relation to what contributes to the development of adaptation in children. PMID:26011538

Integrating self-management and exercise for people living with arthritis.

PubMed

Mendelson, A D; McCullough, C; Chan, A

2011-02-01

The Program for Arthritis Control through Education and Exercise, PACE-Ex™, is an arthritis self-management program incorporating principles and practice of self-management, goal setting and warm water exercise. The purpose of this program review is to examine the impact of PACE-Ex on participants' self-efficacy for condition management, self-management behaviors, goal achievement levels and self-reported disability, pain and health status. A retrospective review was conducted on participants who completed PACE-Ex from 1998 to 2006. A total of 347 participants completed 24 PACE-Ex programs [mean age 69.9 (±12.2) years, living with arthritis mean of 14.1 (±13.2) years]. Participants showed statistically significant improvements in their self-efficacy to manage their condition (Program for Rheumatic Independent Self-Management Questionnaire) (P < 0.001) and performance of self-management behaviors (Self-Management Behavior Questionnaire) (P < 0.01). Self-reported health status, disability and pain levels improved post-program (P < 0.01) despite reporting statistically significant increase in the total swollen and tender joint counts (Health Assessment Questionnaire) (P < 0.05). Sixty-eight percent of participants achieved or exceeded their long-term goal as measured by Goal Attainment Scaling. These findings remain to be proven with a more rigorous method yet they suggest that PACE-Ex is a promising intervention that supports healthy living for individuals with arthritis.

Paced QT interval as a risk factor for new-onset left ventricular systolic dysfunction and cardiac death after permanent pacemaker implantation.

PubMed

Cho, Eun Jeong; Park, Seung-Jung; Park, Kyoung Min; On, Young Keun; Kim, June Soo

2016-01-15

Prolongation of corrected QT (QTc) interval reflects an increased risk of fatal arrhythmia and cardiac death in various populations. However, it is not clear whether the paced-QTc (p-QTc) interval is associated with new-onset left ventricular systolic dysfunction (new-LVSD) or cardiac death. In 491 consecutive patients (64 ± 14 years) with preserved LV ejection fraction (64 ± 7%), the p-QTc interval was measured within 2 weeks after PPM implantation. We assessed the rates of new-LVSD and cardiac death based on the degree of p-QTc interval. During the follow-up period (78 ± 51 months), new-LVSD and cardiac death were identified in 53 (10.8%) and 26 (5.3%) patients, respectively. Patients with new-LVSD had more frequent atrioventricular block (P=0.041), a higher percentage of ventricular pacing (P=0.005), a longer p-QRS duration (P<0.001), and more prolonged p-QTc interval (P<0.001) compared to those without new-LVSD. There was a graded increase in the rates of new-LVSD (P<0.001) and cardiac death (P=0.001) from the patients in the lowest to those in the highest tertile of the p-QTc interval. Additionally, the incidence of cardiac death was significantly elevated especially in the patients with new-LVSD and wider p-QTc interval. In Cox regression analyses, the p-QTc interval was independently associated with new-LVSD and cardiac death even after adjusted with various relevant confounding factors. Prolonged p-QTc interval was closely associated with new-LVSD and cardiac death after PPM implantation in patients with preserved LV systolic function. The rate of cardiac death significantly increased especially in patients who showed more p-QTc widening along with new-LVSD. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Left Atrial Size and Function in a Canine Model of Chronic Atrial Fibrillation and Heart Failure

PubMed Central

Goldberg, Adam; Kusunose, Kenya; Qamruddin, Salima; Rodriguez, L. Leonardo; Mazgalev, Todor N.; Griffin, Brian P.; Van Wagoner, David R.; Zhang, Youhua; Popović, Zoran B.

2016-01-01

Background Our aim was to assess how atrial fibrillation (AF) induction, chronicity, and RR interval irregularity affect left atrial (LA) function and size in the setting of underlying heart failure (HF), and to determine whether AF effects can be mitigated by vagal nerve stimulation (VNS). Methods HF was induced by 4-weeks of rapid ventricular pacing in 24 dogs. Subsequently, AF was induced and maintained by atrial pacing at 600 bpm. Dogs were randomized into control (n = 9) and VNS (n = 15) groups. In the VNS group, atrioventricular node fat pad stimulation (310 μs, 20 Hz, 3–7 mA) was delivered continuously for 6 months. LA volume and LA strain data were calculated from bi-weekly echocardiograms. Results RR intervals decreased with HF in both groups (p = 0.001), and decreased further during AF in control group (p = 0.014), with a non-significant increase in the VNS group during AF. LA size increased with HF (p<0.0001), with no additional increase during AF. LA strain decreased with HF (p = 0.025) and further decreased after induction of AF (p = 0.0001). LA strain decreased less (p = 0.001) in the VNS than in the control group. Beat-by-beat analysis showed a curvilinear increase of LA strain with longer preceding RR interval, (r = 0.45, p <0.0001) with LA strain 1.1% higher (p = 0.02) in the VNS-treated animals, independent of preceding RR interval duration. The curvilinear relationship between ratio of preceding and pre-preceding RR intervals, and subsequent LA strain was weaker, (r = 0.28, p = 0.001). However, VNS-treated animals again had higher LA strain (by 2.2%, p = 0.002) independently of the ratio of preceding and pre-preceding RR intervals. Conclusions In the underlying presence of pacing-induced HF, AF decreased LA strain, with little impact on LA size. LA strain depends on the preceding RR interval duration. PMID:26771573

Body position and activity, but not heart rate, affect pump flows in patients with continuous-flow left ventricular assist devices.

PubMed

Muthiah, Kavitha; Gupta, Sunil; Otton, James; Robson, Desiree; Walker, Robyn; Tay, Andre; Macdonald, Peter; Keogh, Anne; Kotlyar, Eugene; Granger, Emily; Dhital, Kumud; Spratt, Phillip; Jansz, Paul; Hayward, Christopher S

2014-08-01

The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs). Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return. Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded. Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p < 0.0001 analysis of variance). With active ankle flexion, LVAD flow returned to baseline. There was no significant change in flow with a 20° head-down tilt with or without ankle flexion exercise. There were no suction events. Centrifugal cfLVAD flows are not significantly affected by changes in heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Left hemisphere specialization for the control of voluntary movement rate.

PubMed

Agnew, John A; Zeffiro, Thomas A; Eden, Guinevere F

2004-05-01

Although persuasive behavioral evidence demonstrates the superior dexterity of the right hand in most people under a variety of conditions, little is known about the neural mechanisms responsible for this phenomenon. As this lateralized superiority is most evident during the performance of repetitive, speeded movement, we used parametric rate variations to compare visually paced movement of the right and left hands. Twelve strongly right-handed subjects participated in a functional magnetic resonance imaging (fMRI) experiment involving variable rate thumb movements. For movements of the right hand, contralateral rate-related activity changes were identified in the precentral gyrus, thalamus, and posterior putamen. For left-hand movements, activity was seen only in the contralateral precentral gyrus, consistent with the existence of a rate-sensitive motor control subsystem involving the left, but not the right, medial premotor corticostriatal loop in right-handed individuals. We hypothesize that the right hemisphere system is less skilled at controlling variable-rate movements and becomes maximally engaged at a lower movement rate without further modulation. These findings demonstrate that right- and left-hand movements engage different neural systems to control movement, even during a relatively simple thumb flexion task. Specialization of the left hemisphere corticostriatal system for dexterity is reflected in asymmetric mechanisms for movement rate control.

The impact of weight classification on safety: timing steps to adapt to external constraints

PubMed Central

Gill, S.V.

2015-01-01

Objectives: The purpose of the current study was to evaluate how weight classification influences safety by examining adults’ ability to meet a timing constraint: walking to the pace of an audio metronome. Methods: With a cross-sectional design, walking parameters were collected as 55 adults with normal (n=30) and overweight (n=25) body mass index scores walked to slow, normal, and fast audio metronome paces. Results: Between group comparisons showed that at the fast pace, those with overweight body mass index (BMI) had longer double limb support and stance times and slower cadences than the normal weight group (all ps<0.05). Examinations of participants’ ability to meet the metronome paces revealed that participants who were overweight had higher cadences at the slow and fast paces (all ps<0.05). Conclusions: Findings suggest that those with overweight BMI alter their gait to maintain biomechanical stability. Understanding how excess weight influences gait adaptation can inform interventions to improve safety for individuals with obesity. PMID:25730658

Effect of steroid eluting versus conventional electrodes on propafenone induced rise in chronic ventricular pacing threshold.

PubMed

Cornacchia, D; Fabbri, M; Maresta, A; Nigro, P; Sorrentino, F; Puglisi, A; Ricci, R; Peraldo, C; Fazzari, M; Pistis, G

1993-12-01

The aim of this study was to evaluate chronic ventricular pacing threshold increase after oral propafenone therapy. Eighty-three patients affected by advanced atrioventricular block and sick sinus syndrome were studied at least 3 months after pacemaker implantation, before and after oral propafenone therapy (450-900 mg/day based on body weight). The patients were subdivided into three groups according to the type of unipolar electrode that was implanted: group I (41 patients) Medtronic CapSure 4003, group II (30 patients) Medtronic Target Tip 4011, and group III (12 patients) Osypka Vy screw-in lead. In all cases a Medtronic unipolar pacemaker was implanted: 30 Minix, 23 Activitrax, 14 Elite, 12 Legend, and 4 Pasys. Propafenone blood level was measured in 75 patients 3-5 hours after propafenone administration. The pacing autothreshold was measured at 0.8 V, 1.6 V, and 2.5 V by reducing pulse width. At the three different outputs before and after propafenone, threshold increments were significantly lower in group I in comparison with group II and group III (propafenone ranging from < 0.001 to < 0.05). No significant difference was found in pacing impedance or in propafenone plasma concentration in the three groups. Strength-duration curves were drawn for each group at baseline and after propafenone administration. Before propafenone, in group I, the knee was markedly shifted to the left and downward as compared to the classic curve, so that the steep part was predominant; in group II and group III this shift was progressively less evident.(ABSTRACT TRUNCATED AT 250 WORDS)

Loss of Pace Capture on the Ablation Line During Pulmonary Vein Isolation versus "Dormant Conduction": Is Adenosine Expendable?

PubMed

Schaeffer, Benjamin; Willems, Stephan; Sultan, Arian; Hoffmann, Boris A; Lüker, Jakob; Schreiber, Doreen; Akbulak, Ruken; Moser, Julia; Kuklik, Pawel; Steven, Daniel

2015-10-01

Permanent pulmonary vein isolation (PVI) remains an essential goal of ablation therapy in patients with atrial fibrillation. Aim of this study was the intraindividual comparison of unexcitability to pacing along the ablation line versus dormant conduction (DC) as additional procedural endpoints. A total of 58 patients with paroxysmal atrial fibrillation (PAF) underwent PVI by circumferential ablation of ipsilateral pulmonary veins (PVs), followed by testing for DC by adenosine administration. Irrespective of the presence of DC, pacing along the ablation line for left atrium capture was performed and additional radio frequency energy applied if necessary. PVs with initial DC were retested after achieving unexcitability. PVI was achieved in 224 of 224 PVs. In 33 of 224 PVs (15%) DC was revealed. At 92 of 112 ablation lines (82%) sites of excitability were found. Three (9%) of the initial 33 PVs with DC showed further DC after achieving unexcitability at repeated testing. Thirty-two of 33 assumed areas of unmasked PV-LA reconduction as revealed by DC-testing showed a corresponding site of excitability on the ablation line. After a follow-up of 11.6 ± 3.4 months 79% of patients were free of arrhythmia. Pacing for unexcitability can safely identify potential sites of DC and even sites that would have not been detected by testing for DC. Unexcitability, therefore, serves as a suitable and safe procedural endpoint not only for patients with contraindications to adenosine administration. Our data suggest that adenosine may be expendable when achieving unexcitability along the ablation line. © 2015 Wiley Periodicals, Inc.

Computerized analysis of the 12-lead electrocardiogram to identify epicardial ventricular tachycardia exit sites.

PubMed

Yokokawa, Miki; Jung, Dae Yon; Joseph, Kim K; Hero, Alfred O; Morady, Fred; Bogun, Frank

2014-11-01

Twelve-lead electrocardiogram (ECG) criteria for epicardial ventricular tachycardia (VT) origins have been described. In patients with structural heart disease, the ability to predict an epicardial origin based on QRS morphology is limited and has been investigated only for limited regions in the heart. The purpose of this study was to determine whether a computerized algorithm is able to accurately differentiate epicardial vs endocardial origins of ventricular arrhythmias. Endocardial and epicardial pace-mapping were performed in 43 patients at 3277 sites. The 12-lead ECGs were digitized and analyzed using a mixture of gaussian model (MoG) to assess whether the algorithm was able to identify an epicardial vs endocardial origin of the paced rhythm. The MoG computerized algorithm was compared to algorithms published in prior reports. The computerized algorithm correctly differentiated epicardial vs endocardial pacing sites for 80% of the sites compared to an accuracy of 42% to 66% of other described criteria. The accuracy was higher in patients without structural heart disease than in those with structural heart disease (94% vs 80%, P = .0004) and for right bundle branch block (82%) compared to left bundle branch block morphologies (79%, P = .001). Validation studies showed the accuracy for VT exit sites to be 84%. A computerized algorithm was able to accurately differentiate the majority of epicardial vs endocardial pace-mapping sites. The algorithm is not region specific and performed best in patients without structural heart disease and with VTs having a right bundle branch block morphology. Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

'PACE-Gate': When clinical trial evidence meets open data access.

PubMed

Geraghty, Keith J

2017-08-01

Science is not always plain sailing and sometimes the voyage is across an angry sea. A recent clinical trial of treatments for chronic fatigue syndrome (the PACE trial) has whipped up a storm of controversy. Patients claim the lead authors overstated the effectiveness of cognitive behavioural therapy and graded exercise therapy by lowering the thresholds they used to determine improvement. In this extraordinary case, patients discovered that the treatments tested had much lower efficacy after an information tribunal ordered the release of data from the PACE trial to a patient who had requested access using a freedom of information request.

Diaphragm pacing system implanted in a patient with ALS.

PubMed

Kotan, Dilcan; Kaymak, Kamil; Gündogdu, Aslı Aksoy

2016-08-10

The diaphragm pacing system (DPS) is a life quality improving operation in amyotrophic lateral sclerosis (ALS) patients who need mechanical ventilation or have chronic respiratory insufficiency. This procedure is gaining in popularity, and the number of centers implanting diaphragm pacing systems (DPS) is increasing. DPS delays the need for a ventilation machine in the early stages of Amyotrophic lateral sclerosis (ALS) disease. In this case study, we present a young female ALS patient. A DPS was implanted after respiratory insufficiency began. In the one-year follow-up period following her operation, her need for ventilatory support disappeared.

Fixation-related FMRI analysis in the domain of reading research: using self-paced eye movements as markers for hemodynamic brain responses during visual letter string processing.

PubMed

Richlan, Fabio; Gagl, Benjamin; Hawelka, Stefan; Braun, Mario; Schurz, Matthias; Kronbichler, Martin; Hutzler, Florian

2014-10-01

The present study investigated the feasibility of using self-paced eye movements during reading (measured by an eye tracker) as markers for calculating hemodynamic brain responses measured by functional magnetic resonance imaging (fMRI). Specifically, we were interested in whether the fixation-related fMRI analysis approach was sensitive enough to detect activation differences between reading material (words and pseudowords) and nonreading material (line and unfamiliar Hebrew strings). Reliable reading-related activation was identified in left hemisphere superior temporal, middle temporal, and occipito-temporal regions including the visual word form area (VWFA). The results of the present study are encouraging insofar as fixation-related analysis could be used in future fMRI studies to clarify some of the inconsistent findings in the literature regarding the VWFA. Our study is the first step in investigating specific visual word recognition processes during self-paced natural sentence reading via simultaneous eye tracking and fMRI, thus aiming at an ecologically valid measurement of reading processes. We provided the proof of concept and methodological framework for the analysis of fixation-related fMRI activation in the domain of reading research. © The Author 2013. Published by Oxford University Press.

Cardiac optogenetic pacing in drosophila melanogaster using red-shifted opsins (Conference Presentation)

NASA Astrophysics Data System (ADS)

Men, Jing; Li, Airong; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

2017-02-01

Electrical pacing is the current gold standard for investigation of mammalian cardiac electrical conduction systems as well as for treatment of certain cardiac pathologies. However, this method requires an invasive surgical procedure to implant the pacing electrodes. Recently, optogenetic pacing has been developed as an alternative, non-invasive method for heartbeat pacing in animals. It induces heartbeats by shining pulsed light on transgene-generated microbial opsins which in turn activate light gated ion channels in animal hearts. However, commonly used opsins, such as channelrhodopsin-2 (ChR2), require short light wavelength stimulation (475 nm), which is strongly absorbed and scattered by tissue. Here, we expressed recently engineered red-shifted opsins, ReaChR and CsChrimson, in the heart of a well-developed animal model, Drosophila melanogaster, for the first time. Optogenetic pacing was successfully conducted in both ReaChR and CsChrimson flies at their larval, pupal, and adult stages using 617 nm excitation light pulse, enabling a much deeper tissue penetration compared to blue stimulation light. A customized high speed and ultrahigh resolution OCM system was used to non-invasively monitor the heartbeat pacing in Drosophila. Compared to previous studies on optogenetic pacing of Drosophila, higher penetration depth of optogenetic excitation light was achieved in opaque late pupal flies. Lower stimulating power density is needed for excitation at each developmental stage of both groups, which improves the safety of this technique for heart rhythm studies.

Sensors for rate responsive pacing

PubMed Central

Dell'Orto, Simonetta; Valli, Paolo; Greco, Enrico Maria

2004-01-01

Advances in pacemaker technology in the 1980s have generated a wide variety of complex multiprogrammable pacemakers and pacing modes. The aim of the present review is to address the different rate responsive pacing modalities presently available in respect to physiological situations and pathological conditions. Rate adaptive pacing has been shown to improve exercise capacity in patients with chronotropic incompetence. A number of activity and metabolic sensors have been proposed and used for rate control. However, all sensors used to optimize pacing rate metabolic demands show typical limitations. To overcome these weaknesses the use of two sensors has been proposed. Indeed an unspecific but fast reacting sensor is combined with a more specific but slower metabolic one. Clinical studies have demonstrated that this methodology is suitable to reproduce normal sinus behavior during different types and loads of exercise. Sensor combinations require adequate sensor blending and cross checking possibly controlled by automatic algorithms for sensors optimization and simplicity of programming. Assessment and possibly deactivation of some automatic functions should be also possible to maximize benefits from the dual sensor system in particular conditions. This is of special relevance in patient whose myocardial contractility is limited such as in subjects with implantable defibrillators and biventricular pacemakers. The concept of closed loop pacing, implementing a negative feedback relating pacing rate and the control signal, will provide new opportunities to optimize dual-sensors system and deserves further investigation. The integration of rate adaptive pacing into defibrillators is the natural consequence of technical evolution. PMID:16943981

Lessons in Commercial PACE Leadership: The Path from Legislation to Launch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leventis, G; Schwartz, LC; Kramer, C

Nonresidential buildings are responsible for over a quarter of primary energy consumption in the United States. Efficiency improvements in these buildings could result in significant energy and utility bill savings. To unlock those potential savings, a number of market barriers to energy efficiency must be addressed. Commercial Property Assessed Clean Energy (C-PACE) financing programs can help overcome several of these barriers with minimal investment from state and local governments. With programs established or under development in 22 states, and at least $521 million in investments so far, other state and local governments are interested in bringing the benefits of C-PACEmore » to their jurisdictions. Lessons in Commercial PACE Leadership: The Path from Legislation to Launch, aims to fast track the set-up of C-PACE programs for state and local governments by capturing the lessons learned from leaders. The report examines the list of potential program design options and important decision points in setting up a C-PACE program, tradeoffs for available options, and experiences of stakeholders that have gone through (or are going through) the process. C-PACE uses a voluntary special property assessment to facilitate energy and other improvements in commercial buildings. For example: - Long financing terms under C-PACE can produce cash flow-positive -- projects to help overcome a focus on short paybacks. - Payment obligations can transfer to subsequent owners, mitigating concern about investing in improvements for a building that may be sold before the return on the investment is fully realized. - 100% of both hard and soft costs can be financed. To capture the benefits of C-PACE financing, state and local governments must navigate numerous decision points and engage with stakeholders to set-up or join a program. Researchers interviewed experts (including state and local sponsors, program administrators, capital providers and industry experts) on their lessons learned and arrived at the following key takeaways for state and local leaders: Enabling legislation: Carefully developed enabling legislation (which includes certain key provisions) and early stakeholder input can greatly improve the chances of program success. Options for program administrative structure: At least four program administrative structures are in use; certain administrative structures inherently result in more standardized product offerings and, potentially, economies of scale. Approaches to program and project capitalization: Two approaches to capitalization have been used. Bonding (project capital is raised through a bond sale) and direct funding (capital providers fund projects directly); programs can rely on one capital provider (a closed market) or allow multiple capital providers to participate (an open market). What and who qualifies for the program: Some programs require a minimum project savings-to-investment ratio; other programs encourage it or are indifferent. Estimating and documenting project energy cost saving: Estimating and documenting energy and cost savings can add costs to projects but also demonstrate C-PACE program value. Stakeholder engagement: Key stakeholder groups to engage include community leaders, local governments, building owners, contractors, utilities, capital providers and mortgage holders; stakeholder engagement should be tailored to each particular group. Start-up and ongoing costs: Understanding set-up and ongoing costs can help program sponsors plan for funding C-PACE programs and projects. The U.S. Department of Energy's Office of Weatherization and Intergovernmental Programs funded the report.« less

Hepatic lesions: improved image quality and detection with the periodically rotated overlapping parallel lines with enhanced reconstruction technique--evaluation of SPIO-enhanced T2-weighted MR images.

PubMed

Hirokawa, Yuusuke; Isoda, Hiroyoshi; Maetani, Yoji S; Arizono, Shigeki; Shimada, Kotaro; Okada, Tomohisa; Shibata, Toshiya; Togashi, Kaori

2009-05-01

To evaluate the effectiveness of the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technique for superparamagnetic iron oxide (SPIO)-enhanced T2-weighted magnetic resonance (MR) imaging with respiratory compensation with the prospective acquisition correction (PACE) technique in the detection of hepatic lesions. The institutional human research committee approved this prospective study, and all patients provided written informed consent. Eighty-one patients (mean age, 58 years) underwent hepatic 1.5-T MR imaging. Fat-saturated T2-weighted turbo spin-echo images were acquired with the PACE technique and with and without the PROPELLER method after administration of SPIO. Images were qualitatively evaluated for image artifacts, depiction of liver edge and intrahepatic vessels, overall image quality, and presence of lesions. Three radiologists independently assessed these characteristics with a five-point confidence scale. Diagnostic performance was assessed with receiver operating characteristic (ROC) curve analysis. Quantitative analysis was conducted by measuring the liver signal-to-noise ratio (SNR) and the lesion-to-liver contrast-to-noise ratio (CNR). The Wilcoxon signed rank test and two-tailed Student t test were used, and P < .05 indicated a significant difference. MR imaging with the PROPELLER and PACE techniques resulted in significantly improved image quality, higher sensitivity, and greater area under the ROC curve for hepatic lesion detection than did MR imaging with the PACE technique alone (P < .001). The mean liver SNR and the lesion-to-liver CNR were higher with the PROPELLER technique than without it (P < .001). T2-weighted MR imaging with the PROPELLER and PACE technique and SPIO enhancement is a promising method with which to improve the detection of hepatic lesions. (c) RSNA, 2009.

The Role of Echocardiography in the Optimization of Cardiac Resynchronization Therapy: Current Evidence and Future Perspectives.

PubMed

Spartalis, Michael; Tzatzaki, Eleni; Spartalis, Eleftherios; Damaskos, Christos; Athanasiou, Antonios; Livanis, Efthimios; Voudris, Vassilis

2017-01-01

Cardiac resynchronization therapy (CRT) has become a mainstay in the management of heart failure. Up to one-third of patients who received resynchronization devices do not experience the full benefits of CRT. The clinical factors influencing the likelihood to respond to the therapy are wide QRS complex, left bundle branch block, female gender, non-ischaemic cardiomyopathy (highest responders), male gender, ischaemic cardiomyopathy (moderate responders) and narrow QRS complex, non-left bundle branch block (lowest, non-responders). This review provides a conceptual description of the role of echocardiography in the optimization of CRT. A literature survey was performed using PubMed database search to gather information regarding CRT and echocardiography. A total of 70 studies met selection criteria for inclusion in the review. Echocardiography helps in the initial selection of the patients with dyssynchrony, which will benefit the most from optimal biventricular pacing and provides a guide to left ventricular (LV) lead placement during implantation. Different echocardiographic parameters have shown promise and can offer the possibility of patient selection, response prediction, lead placement optimization strategies and optimization of device configurations. LV ejection fraction along with specific electrocardiographic criteria remains the cornerstone of CRT patient selection. Echocardiography is a non-invasive, cost-effective, highly reproducible method with certain limitations and accuracy that is affected by measurement errors. Echocardiography can assist with the identification of the appropriate electromechanical substrate of CRT response and LV lead placement. The targeted approach can improve the haemodynamic response, as also the patient-specific parameters estimation.

The Role of Echocardiography in the Optimization of Cardiac Resynchronization Therapy: Current Evidence and Future Perspectives

PubMed Central

Spartalis, Michael; Tzatzaki, Eleni; Spartalis, Eleftherios; Damaskos, Christos; Athanasiou, Antonios; Livanis, Efthimios; Voudris, Vassilis

2017-01-01

Background: Cardiac resynchronization therapy (CRT) has become a mainstay in the management of heart failure. Up to one-third of patients who received resynchronization devices do not experience the full benefits of CRT. The clinical factors influencing the likelihood to respond to the therapy are wide QRS complex, left bundle branch block, female gender, non-ischaemic cardiomyopathy (highest responders), male gender, ischaemic cardiomyopathy (moderate responders) and narrow QRS complex, non-left bundle branch block (lowest, non-responders). Objective: This review provides a conceptual description of the role of echocardiography in the optimization of CRT. Method: A literature survey was performed using PubMed database search to gather information regarding CRT and echocardiography. Results: A total of 70 studies met selection criteria for inclusion in the review. Echocardiography helps in the initial selection of the patients with dyssynchrony, which will benefit the most from optimal biventricular pacing and provides a guide to left ventricular (LV) lead placement during implantation. Different echocardiographic parameters have shown promise and can offer the possibility of patient selection, response prediction, lead placement optimization strategies and optimization of device configurations. Conclusion: LV ejection fraction along with specific electrocardiographic criteria remains the cornerstone of CRT patient selection. Echocardiography is a non-invasive, cost-effective, highly reproducible method with certain limitations and accuracy that is affected by measurement errors. Echocardiography can assist with the identification of the appropriate electromechanical substrate of CRT response and LV lead placement. The targeted approach can improve the haemodynamic response, as also the patient-specific parameters estimation. PMID:29387277

Loss of pace capture after radiofrequency application predicts the formation of uniform transmural lesions.

PubMed

Kosmidou, Ioanna; Houde-Walter, Haley; Foley, Lori; Michaud, Gregory

2013-04-01

Lesion transmurality is critical to procedural success in radiofrequency catheter ablation. We sought to determine whether loss of pace capture (PC) with high-output unipolar and/or bipolar pacing predicts the formation of uniform transmural lesions. Ten juvenile swine were anaesthetized and prepped under sterile conditions. Seventy-seven isolated radiofrequency applications (RFAs) using a 3.5 mm tip-irrigated catheter were available for analysis. Pace capture was assessed before and after RFA at 10 mA/2 ms and catheter stability verified with a three-dimensional mapping system. Pace capture was defined as 1 : 1 or intermittent local capture per paced beat. Myocardial contact and catheter orientation were assessed using intracardiac echo. Endocardial and epicardial lesion areas were measured after sacrifice using 2,3,5-triphenyltetrazolium chloride staining. A uniform transmural lesion was defined as an epicardial-to-endocardial surface ratio (epi/endo) ≥ 76%. Seventy-four per cent of lesions were transmural and 55.8% of lesions had an epi/endo ratio ≥ 76%. In all, 79.2% of lesions associated with loss of bipolar PC were uniform whereas 20.8% of lesions with loss of bipolar PC were non-uniform (P = 0.006). Loss of bipolar PC was associated with higher mean epicardial/endocardial ratio compared with lesions with persistent PC (P = 0.019). Echocardiographic evidence of optimal catheter contact during RFA improved the predictive accuracy of uniform lesion formation when loss of bipolar PC was noted after RFA. Loss of bipolar PC after RFA is associated with the formation of uniform lesions in atrial tissue. Optimal catheter contact further improves the predictive accuracy associated with loss of PC.

Will the Conscious-Subconscious Pacing Quagmire Help Elucidate the Mechanisms of Self-Paced Exercise? New Opportunities in Dual Process Theory and Process Tracing Methods.

PubMed

Micklewright, Dominic; Kegerreis, Sue; Raglin, John; Hettinga, Florentina

2017-07-01

The extent to which athletic pacing decisions are made consciously or subconsciously is a prevailing issue. In this article we discuss why the one-dimensional conscious-subconscious debate that has reigned in the pacing literature has suppressed our understanding of the multidimensional processes that occur in pacing decisions. How do we make our decisions in real-life competitive situations? What information do we use and how do we respond to opponents? These are questions that need to be explored and better understood, using smartly designed experiments. The paper provides clarity about key conscious, preconscious, subconscious and unconscious concepts, terms that have previously been used in conflicting and confusing ways. The potential of dual process theory in articulating multidimensional aspects of intuitive and deliberative decision-making processes is discussed in the context of athletic pacing along with associated process-tracing research methods. In attempting to refine pacing models and improve training strategies and psychological skills for athletes, the dual-process framework could be used to gain a clearer understanding of (1) the situational conditions for which either intuitive or deliberative decisions are optimal; (2) how intuitive and deliberative decisions are biased by things such as perception, emotion and experience; and (3) the underlying cognitive mechanisms such as memory, attention allocation, problem solving and hypothetical thought.

Substrate characteristics and ablation outcome of left atrial tachycardia in rheumatic mitral valve disease.

PubMed

Chen, Hongwu; Yang, Bing; Ju, Weizhu; Zhang, Fengxiang; Yang, Gang; Gu, Kai; Li, Mingfang; Liu, Hailei; Wang, Zidun; Cao, Kejiang; Chen, Minglong

2017-08-01

Right atrial tachycardia (AT) is a common arrhythmia postsurgical valve replacement in patients with rheumatic heart disease (RHD). However, the substrate and the mechanism of left AT in such patients and the ablation efficacy is less known. Twenty-seven RHD patients with AT were enrolled in this study; nine of them (33%) had left AT. Five and four patients had left AT during the first and second procedure, respectively. A spontaneous scar in the left posterior wall was identified in all patients, and obvious anterior scar in three patients. Dual-roof-dependent AT was found in three patients and macroreentry AT surrounding right pulmonary vein was identified in one patient, two of whom had left anterior scar. Three patients had AT circuit going around the mitral annulus, one of whom had left anterior scar. Entrainment pacing at different sites confirmed the mechanism of these macroreentries. Two patients had a focal origin, one was localized in posterior wall at the edge of the scar and the other one was originated from the left septum with normal voltage. After a mean follow-up of 27.4 ± 7.9 months, the left AT group had a similar recurrence rate compared with the right AT group alone (67% vs 56%, P = 0.58). In the left AT group, 11% of patients had AT recurrence and 56% of patients developed atrial fibrillation. Left atrial AT can occur in RHD patients postmitral valve replacement. Catheter ablation is feasible with high acute success rate. The incidence of late development atrial fibrillation is considerable after successful ablation. © 2017 Wiley Periodicals, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

M., Zimring,; Hoffman, I.; Fuller, M.

The Federal Housing Finance Agency (FHFA) regulates Fannie Mae, Freddie Mac, and the 12 Federal Home Loan Banks (the government-sponsored enterprises - GSEs). On July 6, 2010, FHFA and the Office of the Comptroller of the Currency (OCC) concluded that Property Assessed Clean Energy (PACE) programs 'present significant safety and soundness concerns' to the housing finance industry. This statement came after a year of discussions with state and federal agencies in which PACE, a novel mechanism for financing energy efficiency and renewable energy improvements, has gone from receiving support from the White House, canonization as one of Scientific American's 'Worldmore » Changing Ideas' and legislative adoption in 24 states to questionable relevance, at least in the residential sector. Whether PACE resumes its expansion as an innovative tool for financing energy efficiency and clean generation depends on outcomes in each of the three branches of government - discussions on a PACE pilot phase among federal agencies, litigation in federal court, and legislation in Congress - all highly uncertain. This policy brief addresses the practical impacts of these possible outcomes on existing and emerging PACE programs across the United States and potential paths forward.« less

Conduction Abnormalities and Permanent Pacemaker Implantation After Transcatheter Aortic Valve Replacement Using the Repositionable LOTUS Device: The United Kingdom Experience.

PubMed

Rampat, Rajiv; Khawaja, M Zeeshan; Hilling-Smith, Roland; Byrne, Jonathan; MacCarthy, Philip; Blackman, Daniel J; Krishnamurthy, Arvindra; Gunarathne, Ashan; Kovac, Jan; Banning, Adrian; Kharbanda, Raj; Firoozi, Sami; Brecker, Stephen; Redwood, Simon; Bapat, Vinayak; Mullen, Michael; Aggarwal, Suneil; Manoharan, Ganesh; Spence, Mark S; Khogali, Saib; Dooley, Maureen; Cockburn, James; de Belder, Adam; Trivedi, Uday; Hildick-Smith, David

2017-06-26

The authors report the incidence of pacemaker implantation up to hospital discharge and the factors influencing pacing rate following implantation of the LOTUS bioprosthesis (Boston Scientific, Natick, Massachusetts) in the United Kingdom. Transcatheter aortic valve replacement (TAVR) is associated with a significant need for permanent pacemaker implantation. Pacing rates vary according to the device used. The REPRISE II (Repositionable Percutaneous Replacement of Stenotic Aortic Valve Through Implantation of Lotus Valve System) trial reported a pacing rate of 29% at 30 days after implantation of the LOTUS device. Data were collected retrospectively on 228 patients who had the LOTUS device implanted between March 2013 and February 2015 across 10 centers in the United Kingdom. Twenty-seven patients (12%) had pacemakers implanted pre-procedure and were excluded from the analysis. Patients were aged 81.2 ± 7.7 years; 50.7% were male. The mean pre-procedural QRS duration was 101.7 ± 20.4 ms. More than one-half of the cohort (n = 111, 55%) developed new left bundle branch block (LBBB) following the procedure. Permanent pacemakers were implanted in 64 patients (32%) with a median time to insertion of 3.0 ± 3.4 days. Chief indications for pacing were atrioventricular (AV) block (n = 46, 72%), or LBBB with 1st degree AV block (n = 11, 17%). Amongst those who received a pacemaker following TAVR the pre-procedural electrocardiogram findings included: No conduction disturbance (n = 41, 64%); 1st degree AV block (n = 10, 16%); right bundle branch block (n = 6, 9%) and LBBB (n = 5, 8%). LBBB (but not permanent pacemaker) occurred more frequently in patients who had balloon aortic valvuloplasty before TAVR (odds ratio [OR]: 1.25; p = 0.03). Pre-procedural conduction abnormality (composite of 1st degree AV block, hemiblock, right bundle branch block, LBBB) was independently associated with the need for permanent pacemaker (OR: 2.54; p = 0.048). The absence of aortic valve calcification was also associated with a higher pacing rate (OR: 0.55; p = 0.031). Multivariate regression analysis did not show an independent association between depth of implant, valve oversizing, balloon post-dilatation, and the need for pacing post-procedure. Following implantation of the repositionable LOTUS valve, 55% of patients developed LBBB and 32% of patients required a pacemaker during their index hospital admission. Patients with pre-procedural conduction disturbance and non-calcified aortic valves were more likely to need pacing. No other anatomic features were identified with increased pacing requirement with the LOTUS device. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Safety of transvenous low energy cardioversion of atrial fibrillation in patients with a history of ventricular tachycardia: effects of rate and repolarization time on proarrhythmic risk.

PubMed

Simons, G R; Newby, K H; Kearney, M M; Brandon, M J; Natale, A

1998-02-01

The objective of this study was to assess the safety and efficacy of transvenous low energy cardioversion of atrial fibrillation in patients with ventricular tachycardia and atrial fibrillation and to study the mechanisms of proarrhythmia. Previous studies have demonstrated that cardioversion of atrial fibrillation using low energy, R wave synchronized, direct current shocks applied between catheters in the coronary sinus and right atrium is feasible. However, few data are available regarding the risk of ventricular proarrhythmia posed by internal atrial defibrillation shocks among patients with ventricular arrhythmias or structural heart disease. Atrial defibrillation was performed on 32 patients with monomorphic ventricular tachycardia and left ventricular dysfunction. Shocks were administered during atrial fibrillation (baseline shocks), isoproterenol infusion, ventricular pacing, ventricular tachycardia, and atrial pacing. Baseline shocks were also administered to 29 patients with a history of atrial fibrillation but no ventricular arrhythmias. A total of 932 baseline shocks were administered. No ventricular proarrhythmia was observed after well-synchronized baseline shocks, although rare inductions of ventricular fibrillation occurred after inappropriate T wave sensing. Shocks administered during wide-complex rhythms (ventricular pacing or ventricular tachycardia) frequently induced ventricular arrhythmias, but shocks administered during atrial pacing at identical ventricular rates did not cause proarrhythmia. The risk of ventricular proarrhythmia after well-synchronized atrial defibrillation shocks administered during narrow-complex rhythms is low, even in patients with a history of ventricular tachycardia. The mechanism of proarrhythmia during wide-complex rhythms appears not to be related to ventricular rate per se, but rather to the temporal relationship between shock delivery and the repolarization time of the previous QRS complex.

Development of porcine model of chronic tachycardia-induced cardiomyopathy.

PubMed

Paslawska, Urszula; Gajek, Jacek; Kiczak, Liliana; Noszczyk-Nowak, Agnieszka; Skrzypczak, Piotr; Bania, Jacek; Tomaszek, Alicja; Zacharski, Maciej; Sambor, Izabela; Dziegiel, Piotr; Zysko, Dorota; Banasiak, Waldemar; Jankowska, Ewa A; Ponikowski, Piotr

2011-11-17

There are few experimental models of heart failure (HF) in large animals, despite structural and functional similarities to human myocardium. We have developed a porcine model of chronic tachycardia-induced cardiomyopathy. Homogenous siblings of White Large breed swine (n=6) underwent continuous right ventricular (RV) pacing at 170 bpm; 2 subjects served as controls. In the course of RV pacing, animals developed a clinical picture of HF and were presented for euthanasia at subsequent stages: mild, moderate and end-stage HF. Left ventricle (LV) sections were analyzed histologically and relative ANP, BNP, phospholamban and sarcoplasmic reticulum calcium ATPase 2a transcript levels in LV were quantified by real time RT-PCR. In the course of RV pacing, animals demonstrated reduced exercise capacity (time of running until being dyspnoeic: 6.6 ± 0.5 vs. 2.4 ± 1.4 min), LV dilatation (LVEDD: 4.9 ± 0.4 vs. 6.7 ± 0.4 cm), impaired LV systolic function (LVEF: 69 ± 8 vs. 32 ± 7 %), (all baseline vs. before euthanasia, all p<0.001). LV tissues from animals with moderate and end-stage HF demonstrated local foci of interstitial fibrosis, congestion, cardiomyocyte hypertrophy and atrophy, which was not detected in controls and mild HF animals. The up-regulation of ANP and BNP and a reduction in a ratio of sarcoplasmic reticulum calcium ATPase 2a and phospholamban in failing myocardium were observed as compared to controls. In pigs, chronic RV pacing at relatively low rate can be used as an experimental model of HF, as it results in a gradual deterioration of exercise tolerance accompanied by myocardial remodeling confirmed at subcellular level. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

In vivo mechanical study of helical cardiac pacing electrode interacting with canine myocardium

NASA Astrophysics Data System (ADS)

Zhang, Xiangming; Ma, Nianke; Fan, Hualin; Niu, Guodong; Yang, Wei

2007-06-01

Cardiac pacing is a medical device to help human to overcome arrhythmia and to recover the regular beats of heart. A helical configuration of electrode tip is a new type of cardiac pacing lead distal tip. The helical electrode attaches itself to the desired site of heart by screwing its helical tip into the myocardium. In vivo experiments on anesthetized dogs were carried out to measure the acute interactions between helical electrode and myocardium during screw-in and pull-out processes. These data would be helpful for electrode tip design and electrode/myocardium adherence safety evaluation. They also provide reliability data for clinical site choice of human heart to implant and to fix the pacing lead. A special design of the helical tip using strain gauges is instrumented for the measurement of the screw-in and pull-out forces. We obtained the data of screw-in torques and pull-out forces for five different types of helical electrodes at nine designed sites on ten canine hearts. The results indicate that the screw-in torques increased steplike while the torque time curves presente saw-tooth fashion. The maximum torque has a range of 0.3 1.9 N mm. Obvious differences are observed for different types of helical tips and for different test sites. Large pull-out forces are frequently obtained at epicardium of left ventricle and right ventricle lateral wall, and the forces obtained at right ventricle apex and outflow tract of right ventricle are normally small. The differences in pull-out forces are dictated by the geometrical configuration of helix and regional structures of heart muscle.

Effects of heart rate on experimentally produced mitral regurgitation in dogs.

PubMed

Yoran, C; Yellin, E L; Hori, M; Tsujioka, K; Laniado, S; Sonnenblick, E H; Frater, R W

1983-12-01

The effects of increasing heart rate (HR) on the hemodynamics of acute mitral regurgitation (MR) were studied in 8 open-chest dogs. Filling volume, regurgitant volume and stroke volume were calculated from electromagnetic probe measurements of mitral and aortic flows. The left atrial-left ventricular systolic pressure gradient was measured with micromanometers. The calculated effective mitral regurgitant orifice area varied from 10 to 128 mm2, with a consequent regurgitant fraction (regurgitant volume/filling volume) of 24 to 62%. After crushing the sinus node, HR was increased stepwise from 90 to 180 beats/min by atrial pacing while maintaining aortic pressure constant. With increasing HR, filling volume, stroke volume, regurgitant volume and regurgitant time decreased; total cardiac output, forward cardiac output, regurgitant output, systolic pressure gradient, regurgitant fraction and the regurgitant orifice did not change; left ventricular end-diastolic pressure decreased; and left atrial v-wave amplitude increased. These results indicate that in acute experimental MR with a wide spectrum of incompetence, the relative distribution of forward and regurgitant flows did not change with large increases in HR. At rates greater than 150 beats/min the atrial contraction occurs early and increases the amplitude of the left atrial v wave. This may contribute to the severity of pulmonary congestion in patients with MR.

Real-time magnetic resonance imaging-guided transcatheter aortic valve replacement.

PubMed

Miller, Justin G; Li, Ming; Mazilu, Dumitru; Hunt, Tim; Horvath, Keith A

2016-05-01

To demonstrate the feasibility of Real-time magnetic resonance imaging (rtMRI) guided transcatheter aortic valve replacement (TAVR) with an active guidewire and an MRI compatible valve delivery catheter system in a swine model. The CoreValve system was minimally modified to be MRI-compatible by replacing the stainless steel components with fluoroplastic resin and high-density polyethylene components. Eight swine weighing 60-90 kg underwent rtMRI-guided TAVR with an active guidewire through a left subclavian approach. Two imaging planes (long-axis view and short-axis view) were used simultaneously for real-time imaging during implantation. Successful deployment was performed without rapid ventricular pacing or cardiopulmonary bypass. Postdeployment images were acquired to evaluate the final valve position in addition to valvular and cardiac function. Our results show that the CoreValve can be easily and effectively deployed through a left subclavian approach using rtMRI guidance, a minimally modified valve delivery catheter system, and an active guidewire. This method allows superior visualization before deployment, thereby allowing placement of the valve with pinpoint accuracy. rtMRI has the added benefit of the ability to perform immediate postprocedural functional assessment, while eliminating the morbidity associated with radiation exposure, rapid ventricular pacing, contrast media renal toxicity, and a more invasive procedure. Use of a commercially available device brings this rtMRI-guided approach closer to clinical reality. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Ambulatory Monitoring of Congestive Heart Failure by Multiple Bioelectric Impedance Vectors

PubMed Central

Khoury, Dirar S.; Naware, Mihir; Siou, Jeff; Blomqvist, Andreas; Mathuria, Nilesh S.; Wang, Jianwen; Shih, Hue-Teh; Nagueh, Sherif F.; Panescu, Dorin

2009-01-01

Objectives To investigate properties of multiple bioelectric impedance signals recorded during congestive heart failure (CHF) by utilizing various electrode configurations of an implanted cardiac resynchronization therapy (CRT) system. Background Monitoring of CHF has relied mainly on right-heart sensors. Methods Fifteen normal dogs underwent implantation of CRT systems using standard leads. An additional left atrial (LA) pressure lead-sensor was implanted in 5 dogs. Continuous rapid right ventricular (RV) pacing was applied over several weeks. Left ventricular (LV) catheterization and echocardiography were performed biweekly. Six steady-state impedance signals, utilizing intrathorcaic and intracardiac vectors, were measured via ring (r), coil (c), and device Can electrodes. Results All animals developed CHF after 2–4 weeks of pacing. Impedance diminished gradually during CHF induction, but at varying rates for different vectors. Impedance during CHF decreased significantly in all measured vectors: LVr-Can, −17%; LVr-RVr, −15%; LVr-RAr, −11%; RVr-Can, −12%; RVc-Can, −7%; RAr-Can, −5%. The LVr-Can vector reflected both the fastest and largest change in impedance in comparison to vectors employing only right-heart electrodes, and was highly reflective of changes in LV end-diastolic volume and LA pressure. Conclusions Impedance, acquired via different lead-electrodes, have variable responses to CHF. Impedance vectors employing a LV lead are highly responsive to physiologic changes during CHF. Measuring multiple impedance signals could be useful for optimizing ambulatory monitoring in heart failure patients. PMID:19298923

Heat-acclimatization and pre-cooling: a further boost for endurance performance?

PubMed

Schmit, C; Le Meur, Y; Duffield, R; Robach, P; Oussedik, N; Coutts, A J; Hausswirth, C

2017-01-01

To determine if pre-cooling (PC) following heat-acclimatization (HA) can further improve self-paced endurance performance in the heat, 13 male triathletes performed two 20-km cycling time-trials (TT) at 35 °C, 50% relative humidity, before and after an 8-day training camp, each time with (PC) or without (control) ice vest PC. Pacing strategies, physiological and perceptual responses were assessed during each TT. PC and HA induced moderate (+10 ± 18 W; effect size [ES] 4.4 ± 4.6%) and very large (+28 ± 19 W; ES 11.7 ± 4.1%) increases in power output (PO), respectively. The overall PC effect became unclear after HA (+4 ± 14 W; ES 1.4 ± 3.0%). However, pacing analysis revealed that PC remained transiently beneficial post-HA, i.e., during the first half of the TT. Both HA and PC pre-HA were characterized by an enhanced PO without increased cardio-thermoregulatory or perceptual disturbances, while post-HA PC only improved thermal comfort. PC improved 20-km TT performance in unacclimatized athletes, but an 8-day HA period attenuated the magnitude of this effect. The respective converging physiological responses to HA and PC may explain the blunting of PC effectiveness. However, perceptual benefits from PC can still account for the small alterations to pacing noted post-HA. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Electrophysiological determinants of hypokalaemia-induced arrhythmogenicity in the guinea-pig heart.

PubMed

Osadchii, O E; Olesen, S P

2009-12-01

Hypokalaemia is an independent risk factor contributing to arrhythmic death in cardiac patients. In the present study, we explored the mechanisms of hypokalaemia-induced tachyarrhythmias by measuring ventricular refractoriness, spatial repolarization gradients, and ventricular conduction time in isolated, perfused guinea-pig heart preparations. Epicardial and endocardial monophasic action potentials from distinct left ventricular (LV) and right ventricular (RV) recording sites were monitored simultaneously with volume-conducted electrocardiogram (ECG) during steady-state pacing and following a premature extrastimulus application at progressively reducing coupling stimulation intervals in normokalaemic and hypokalaemic conditions. Hypokalaemic perfusion (2.5 mm K(+) for 30 min) markedly increased the inducibility of tachyarrhythmias by programmed ventricular stimulation and rapid pacing, prolonged ventricular repolarization and shortened LV epicardial and endocardial effective refractory periods, thereby increasing the critical interval for LV re-excitation. Hypokalaemia increased the RV-to-LV transepicardial repolarization gradients but had no effect on transmural dispersion of APD(90) and refractoriness across the LV wall. As determined by local activation time recordings, the LV-to-RV transepicardial conduction and the LV transmural (epicardial-to-endocardial) conduction were slowed in hypokalaemic heart preparations. This change was attributed to depressed diastolic excitability as evidenced by increased ventricular pacing thresholds. These findings suggest that hypokalaemia-induced arrhythmogenicity is attributed to shortened LV refractoriness, increased critical intervals for LV re-excitation, amplified RV-to-LV transepicardial repolarization gradients and slowed ventricular conduction in the guinea-pig heart.

Manual vs. automatic capture management in implantable cardioverter defibrillators and cardiac resynchronization therapy defibrillators.

PubMed

Murgatroyd, Francis D; Helmling, Erhard; Lemke, Bernd; Eber, Bernd; Mewis, Christian; van der Meer-Hensgens, Judith; Chang, Yanping; Khalameizer, Vladimir; Katz, Amos

2010-06-01

The Secura ICD and Consulta CRT-D are the first defibrillators to have automatic right atrial (RA), right ventricular (RV), and left ventricular (LV) capture management (CM). Complete CM was evaluated in an implantable cardioverter defibrillator (ICD) population. Two prospective clinical studies were conducted in 28 centres in Europe and Israel. Automatic CM data were compared with manual threshold measurements, the CM applicability was determined, and adjustments to pacing outputs were analysed. In total, 160 patients [age 64.6 +/- 10.4 years, 77% male, 80 ICD and 80 cardiac resynchronization therapy defibrillator (CRT-D)] were included. The differences between automatic and manual measurements were 2.5 V) due to raised RA threshold in seven (4.4%), high RV threshold in nine (5.6%), and high LV threshold in three patients (3.8%). All high threshold detections and all automatic modulations of pacing output were adjudicated appropriate. Complete CM adjusts pacing output appropriately, permitting a reduction in office visits while it may maximize device longevity. The study was registered at ClinicalTrials.gov identifiers: NCT00526227 and NCT00526162.

Determinants of the development of mitral regurgitation in pacing-induced heart failure.

PubMed

Takagaki, Masami; McCarthy, Patrick M; Goormastic, Marlene; Ochiai, Yoshie; Doi, Kazuyoshi; Kopcak, Michael W; Tabata, Tomotsugu; Cardon, Lisa A; Thomas, James D; Fukamachi, Kiyotaka

2003-01-01

The pacing-induced heart failure model provides an opportunity to assess the structural and functional determinants of mitral regurgitation (MR) in dilated cardiomyopathy. This study aimed to evaluate MR to better understand the multitude of factors contributing to its development. Heart failure was induced by rapid ventricular pacing (230 beats/min) in 40 mongrel dogs. Left ventricular (LV) size and MR were evaluated echocardiographically. LV contractility was analyzed using a conductance catheter. MR increased to mild in 12 animals (regurgitant orifice area, 0.06+/-0.05 cm(2)), moderate in 15 (0.14+/-0.07 cm(2)), and severe in 13 (0.34+/-0.16 cm(2)). The grade of MR had an inverse relationships with E(max) (the slope of the end-systolic pressure-volume relationship, p<0.01) and dE/dt (the slope of the maximum rate of change of pressure-end-diastolic volume [V(ED)] relationship, p<0.01) and positive relationships with V(ED) and end-diastolic cross-sectional areas and lengths (p<0.05) by univariate analysis. The dE/dt had an independently significant (p<0.01) relationship by multivariable logistic regression. Many factors influence the development of MR and because of its similarity to the clinical situation, this model can be used to investigate MR and heart failure, as well as new surgical therapies.

The Longitudinal Study of Aging in Human Young Adults: Knowledge Gaps and Research Agenda.

PubMed

Moffitt, Terrie E; Belsky, Daniel W; Danese, Andrea; Poulton, Richie; Caspi, Avshalom

2017-02-01

To prevent onset of age-related diseases and physical and cognitive decline, interventions to slow human aging and extend health span must eventually be applied to people while they are still young and healthy. Yet most human aging research examines older adults, many with chronic disease, and little is known about aging in healthy young humans. This article explains how this knowledge gap is a barrier to extending health span and puts forward the case that geroscience should invest in researching the pace of aging in young adults. As one illustrative example, we describe an initial effort to study the pace of aging in a young-adult birth cohort by using repeated waves of biomarkers collected across the third and fourth decades to quantify the pace of coordinated physiological deterioration across multiple organ systems (eg, pulmonary, periodontal, cardiovascular, renal, hepatic, metabolic, and immune function). Findings provided proof of principle that it is possible to quantify individual variation in the pace of aging in young adults still free of age-related diseases. This article articulates research needs to improve longitudinal measurement of the pace of aging in young people, to pinpoint factors that slow or speed the pace of aging, to compare pace of aging against genomic clocks, to explain slow-aging young adults, and to apply pace of aging in preventive clinical trials of antiaging therapies. This article puts forward a research agenda to fill the knowledge gap concerning lifelong causes of aging. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Effects of Program Embedded Learning Strategies, Using an Imagery Cue Strategy and an Attention Directing Strategy, to Improve Learning from Micro Computer Based Instruction (MCBI).

ERIC Educational Resources Information Center

Taylor, William; And Others

The effects of the Attention Directing Strategy and Imagery Cue Strategy as program embedded learning strategies for microcomputer-based instruction (MCBI) were examined in this study. Eight learning conditions with identical instructional content on the parts and operation of the human heart were designed: either self-paced or externally-paced,…

Pacing-induced regional differences in adenosine receptors mRNA expression in a swine model of dilated cardiomyopathy.

PubMed

Del Ry, Silvia; Cabiati, Manuela; Lionetti, Vincenzo; Aquaro, Giovanni D; Martino, Alessandro; Mattii, Letizia; Morales, Maria-Aurora

2012-01-01

The adenosinergic system is essential in the mediation of intrinsic protection and myocardial resistance to insult; it may be considered a cardioprotective molecule and adenosine receptors (ARs) represent potential therapeutic targets in the setting of heart failure (HF). The aim of the study was to test whether differences exist between mRNA expression of ARs in the anterior left ventricle (LV) wall (pacing site: PS) compared to the infero septal wall (opposite region: OS) in an experimental model of dilated cardiomyopathy. Cardiac tissue was collected from LV PS and OS of adult male minipigs with pacing-induced HF (n = 10) and from a control group (C, n = 4). ARs and TNF-α mRNA expression was measured by Real Time-PCR and the results were normalized with the three most stably expressed genes (GAPDH, HPRT1, TBP). Immunohistochemistry analysis was also performed. After 3 weeks of pacing higher levels of expression for each analyzed AR were observed in PS except for A(1)R (A(1)R: C = 0.6±0.2, PS = 0.1±0.04, OS = 0.04±0.01, p<0.0001 C vs. PS and OS respectively; A(2A)R: C = 1.04±0.59, PS = 2.62±0.79, OS = 2.99±0.79; A(2B)R: C = 1.2±0.1, PS = 5.59±2.3, OS = 1.59±0.46; A(3)R: C = 0.76±0.18, PS = 8.40±3.38, OS = 4.40±0.83). Significant contractile impairment and myocardial hypoperfusion were observed at PS after three weeks of pacing as compared to OS. TNF-α mRNA expression resulted similar in PS (6.3±2.4) and in OS (5.9±2.7) although higher than in control group (3.4±1.5). ARs expression was mainly detected in cardiomyocytes. This study provided new information on ARs local changes in the setting of LV dysfunction and on the role of these receptors in relation to pacing-induced abnormalities of myocardial perfusion and contraction. These results suggest a possible therapeutic role of adenosine in patients with HF and dyssynchronous LV contraction.

Use of an Active-Fixation Coronary Sinus Lead to Implant a Biventricular Pacemaker via the Femoral Vein

PubMed Central

Shandling, Adrian; Donohue, Daniel; Tobias, Serge; Wu, Iris; Brar, Ramandeep

2010-01-01

Cardiac resynchronization therapy, which involves the placement of a pacing lead in the right atrium and in each ventricle, is effective in treating heart failure that is caused by left bundle branch block and cardiomyopathy. The left ventricular lead is usually placed into a lateral branch of the coronary sinus via the subclavian route. When the subclavian route is unavailable, insertion of a standard, passive-fixation coronary sinus lead via the femoral approach is feasible; however, the likelihood of subsequent dislodgment is high. Herein, we describe the placement of a novel, self-retaining, active-fixation coronary sinus lead—the Attain StarFix® Model 4195 OTW Lead—in an elderly heart-failure patient, via the femoral approach. We believe that this is the 1st report of this procedure. PMID:20200636

How to Sync to the Beat of a Persistent Fractal Metronome without Falling Off the Treadmill?

PubMed Central

Roerdink, Melvyn; Daffertshofer, Andreas; Marmelat, Vivien; Beek, Peter J.

2015-01-01

In rehabilitation, rhythmic acoustic cues are often used to improve gait. However, stride-time fluctuations become anti-persistent with such pacing, thereby deviating from the characteristic persistent long-range correlations in stride times of self-paced walking healthy adults. Recent studies therefore experimented with metronomes with persistence in interbeat intervals and successfully evoked persistent stride-time fluctuations. The objective of this study was to examine how participants couple their gait to a persistent metronome, evoking persistently longer or shorter stride times over multiple consecutive strides, without wandering off the treadmill. Twelve healthy participants walked on a treadmill in self-paced, isochronously paced and non-isochronously paced conditions, the latter with anti-persistent, uncorrelated and persistent correlations in interbeat intervals. Stride-to-stride fluctuations of stride times, stride lengths and stride speeds were assessed with detrended fluctuation analysis, in conjunction with an examination of the coupling between stride times and stride lengths. Stride-speed fluctuations were anti-persistent for all conditions. Stride-time and stride-length fluctuations were persistent for self-paced walking and anti-persistent for isochronous pacing. Both stride times and stride lengths changed from anti-persistence to persistence over the four non-isochronous metronome conditions, accompanied by an increasingly stronger coupling between these gait parameters, with peak values for the persistent metronomes. These results revealed that participants were able to follow the beat of a persistent metronome without falling off the treadmill by strongly coupling stride-length fluctuations to the stride-time fluctuations elicited by persistent metronomes, so as to prevent large positional displacements along the treadmill. For self-paced walking, in contrast, this coupling was very weak. In combination, these results challenge the premise that persistent metronomes in gait rehabilitation would evoke stride-to-stride dynamics reminiscent of self-paced walking healthy adults. Future studies are recommended to include an analysis of the interrelation between stride times and stride lengths in addition to the correlational structure of either one in isolation. PMID:26230254

How to Sync to the Beat of a Persistent Fractal Metronome without Falling Off the Treadmill?

PubMed

Roerdink, Melvyn; Daffertshofer, Andreas; Marmelat, Vivien; Beek, Peter J

2015-01-01

In rehabilitation, rhythmic acoustic cues are often used to improve gait. However, stride-time fluctuations become anti-persistent with such pacing, thereby deviating from the characteristic persistent long-range correlations in stride times of self-paced walking healthy adults. Recent studies therefore experimented with metronomes with persistence in interbeat intervals and successfully evoked persistent stride-time fluctuations. The objective of this study was to examine how participants couple their gait to a persistent metronome, evoking persistently longer or shorter stride times over multiple consecutive strides, without wandering off the treadmill. Twelve healthy participants walked on a treadmill in self-paced, isochronously paced and non-isochronously paced conditions, the latter with anti-persistent, uncorrelated and persistent correlations in interbeat intervals. Stride-to-stride fluctuations of stride times, stride lengths and stride speeds were assessed with detrended fluctuation analysis, in conjunction with an examination of the coupling between stride times and stride lengths. Stride-speed fluctuations were anti-persistent for all conditions. Stride-time and stride-length fluctuations were persistent for self-paced walking and anti-persistent for isochronous pacing. Both stride times and stride lengths changed from anti-persistence to persistence over the four non-isochronous metronome conditions, accompanied by an increasingly stronger coupling between these gait parameters, with peak values for the persistent metronomes. These results revealed that participants were able to follow the beat of a persistent metronome without falling off the treadmill by strongly coupling stride-length fluctuations to the stride-time fluctuations elicited by persistent metronomes, so as to prevent large positional displacements along the treadmill. For self-paced walking, in contrast, this coupling was very weak. In combination, these results challenge the premise that persistent metronomes in gait rehabilitation would evoke stride-to-stride dynamics reminiscent of self-paced walking healthy adults. Future studies are recommended to include an analysis of the interrelation between stride times and stride lengths in addition to the correlational structure of either one in isolation.

Increased passive stiffness promotes diastolic dysfunction despite improved Ca2+ handling during left ventricular concentric hypertrophy

PubMed Central

Røe, Åsmund T.; Aronsen, Jan Magnus; Skårdal, Kristine; Hamdani, Nazha; Linke, Wolfgang A.; Danielsen, Håvard E.; Sejersted, Ole M.; Sjaastad, Ivar; Louch, William E.

2017-01-01

Abstract Aims Concentric hypertrophy following pressure-overload is linked to preserved systolic function but impaired diastolic function, and is an important substrate for heart failure with preserved ejection fraction. While increased passive stiffness of the myocardium is a suggested mechanism underlying diastolic dysfunction in these hearts, the contribution of active diastolic Ca2+ cycling in cardiomyocytes remains unclear. In this study, we sought to dissect contributions of passive and active mechanisms to diastolic dysfunction in the concentrically hypertrophied heart following pressure-overload. Methods and results Rats were subjected to aortic banding (AB), and experiments were performed 6 weeks after surgery using sham-operated rats as controls. In vivo ejection fraction and fractional shortening were normal, confirming preservation of systolic function. Left ventricular concentric hypertrophy and diastolic dysfunction following AB were indicated by thickening of the ventricular wall, reduced peak early diastolic tissue velocity, and higher E/e’ values. Slowed relaxation was also observed in left ventricular muscle strips isolated from AB hearts, during both isometric and isotonic stimulation, and accompanied by increases in passive tension, viscosity, and extracellular collagen. An altered titin phosphorylation profile was observed with hypophosphorylation of the phosphosites S4080 and S3991 sites within the N2Bus, and S12884 within the PEVK region. Increased titin-based stiffness was confirmed by salt-extraction experiments. In contrast, isolated, unloaded cardiomyocytes exhibited accelerated relaxation in AB compared to sham, and less contracture at high pacing frequencies. Parallel enhancement of diastolic Ca2+ handling was observed, with augmented NCX and SERCA2 activity and lowered resting cytosolic [Ca2+]. Conclusion In the hypertrophied heart with preserved systolic function, in vivo diastolic dysfunction develops as cardiac fibrosis and alterations in titin phosphorylation compromise left ventricular compliance, and despite compensatory changes in cardiomyocyte Ca2+ homeostasis. PMID:28472418

Brief exposure to a self-paced computer-based reading programme and how it impacts reading ability and behaviour problems.

PubMed

Hughes, J Antony; Phillips, Gordon; Reed, Phil

2013-01-01

Basic literacy skills underlie much future adult functioning, and are targeted in children through a variety of means. Children with reading problems were exposed either to a self-paced computer programme that focused on improving phonetic ability, or underwent a classroom-based reading intervention. Exposure was limited to 3 40-min sessions a week, for six weeks. The children were assessed in terms of their reading, spelling, and mathematics abilities, as well as for their externalising and internalising behaviour problems, before the programme commenced, and immediately after the programme terminated. Relative to the control group, the computer-programme improved reading by about seven months in boys (but not in girls), but had no impact on either spelling or mathematics. Children on the programme also demonstrated fewer externalising and internalising behaviour problems than the control group. The results suggest that brief exposure to a self-paced phonetic computer-teaching programme had some benefits for the sample.

Longitudinal assessment of reflexive and volitional saccades in Niemann-Pick Type C disease during treatment with miglustat.

PubMed

Abel, Larry A; Walterfang, Mark; Stainer, Matthew J; Bowman, Elizabeth A; Velakoulis, Dennis

2015-12-21

Niemann-Pick Type C disease (NPC), is an autosomal recessive neurovisceral disorder of lipid metabolism. One characteristic feature of NPC is a vertical supranuclear gaze palsy particularly affecting saccades. However, horizontal saccades are also impaired and as a consequence a parameter related to horizontal peak saccadic velocity was used as an outcome measure in the clinical trial of miglustat, the first drug approved in several jurisdictions for the treatment of NPC. As NPC-related neuropathology is widespread in the brain we examined a wider range of horizontal saccade parameters and to determine whether these showed treatment-related improvement and, if so, if this was maintained over time. Nine adult NPC patients participated in the study; 8 were treated with miglustat for periods between 33 and 61 months. Data were available for 2 patients before their treatment commenced and 1 patient was untreated. Tasks included reflexive saccades, antisaccades and self-paced saccades, with eye movements recorded by an infrared reflectance eye tracker. Parameters analysed were reflexive saccade gain and latency, asymptotic peak saccadic velocity, HSEM-α (the slope of the peak duration-amplitude regression line), antisaccade error percentage, self-paced saccade count and time between refixations on the self-paced task. Data were analysed by plotting the change from baseline as a proportion of the baseline value at each test time and, where multiple data values were available at each session, by linear mixed effects (LME) analysis. Examination of change plots suggested some modest sustained improvement in gain, no consistent changes in asymptotic peak velocity or HSEM-α, deterioration in the already poor antisaccade error rate and sustained improvement in self-paced saccade rate. LME analysis showed statistically significant improvement in gain and the interval between self-paced saccades, with differences over time between treated and untreated patients. Both qualitative examination of change scores and statistical evaluation with LME analysis support the idea that some saccadic parameters are robust indicators of efficacy, and that the variability observed across measures may indicate locally different effects of neurodegeneration and of drug actions.

Evolutionary pattern of improved 1-mile running performance.

PubMed

Foster, Carl; de Koning, Jos J; Thiel, Christian

2014-07-01

The official world records (WR) for the 1-mile run for men (3:43.13) and for women (4:12.58) have improved 12.2% and 32.3%, respectively, since the first WR recognized by the International Association of Athletics Federations. Previous observations have suggested that the pacing pattern for successive laps is characteristically faster-slower-slowest-faster. However, modeling studies have suggested that uneven energy-output distribution, particularly a high velocity at the end of the race, is essentially wasted kinetic energy that could have been used to finish sooner. Here the authors report that further analysis of the pacing pattern in 32 men's WR races is characterized by a progressive reduction in the within-lap variation of pace, suggesting that improving the WR in the 1-mile run is as much about how energetic resources are managed as about the capacity of the athletes performing the race. In the women's WR races, the pattern of lap times has changed little, probably secondary to a lack of depth in the women's fields. Contemporary WR performances have been achieved a coefficient of variation of lap times on the order of 1.5-3.0%. Reasonable projection suggests that the WR is overdue for improving and may require lap times with a coefficient of variation of ~1%.

Posterior shift of the anterior papillary muscle in patients with heart failure: a potential role in the effect of cardiac resynchronization therapy.

PubMed

Hara, Tetsuya; Yamashiro, Kohei; Okajima, Katsunori; Hayashi, Takatoshi; Kajiya, Teishi

2009-11-01

The anatomical relationship between left ventricular pacing site and the anterior papillary muscle (A-PM) may have a major influence on the improvement of mitral regurgitation (MR) in cardiac resynchronization therapy (CRT). The aims of the present study were to assess the anatomical relationship between coronary veins and papillary muscles in patients with and without heart failure (HF), and to examine its contribution to the response to CRT. Sixty-one patients (36 patients with HF, 25 patients without HF) who underwent multi-detector computed tomography were studied. We measured the angle between the anterior papillary muscle and coronary veins (Ang. 1) and the angle between the anterior edge of the left ventricular free wall and A-PM (Ang. 2). Angle 1 of the posterolateral vein in the patients with HF was significantly smaller than those without HF (54.9 +/- 11.1, 68.7 +/- 15.8 degrees, respectively, P = 0.02). Supportively, Angle 2 of patients with HF was larger than that of patients without HF (100 +/- 13.0, 87.3 +/- 10.7 degrees, respectively, P < 0.01). Significant decreases in left ventricular end-diastolic diameter, the grade of MR, and brain natriuretic peptide level after 6 months of CRT were observed (P < 0.01, P = 0.04, P < 0.01, respectively) in patients with severe A-PM displacement (Ang. 2 > 100 degrees), but not in patients with Ang. 2 < 100 degrees. A-PM tends to be located in a more posterior wall in patients with HF. Displacement of A-PM may have a potential role as a predictor of the response to CRT.

Imaging of Pericardiophrenic Bundles Using Multislice Spiral Computed Tomography for Phrenic Nerve Anatomy.

PubMed

Wang, Yan-Jing; Liu, Lin; Zhang, Meng-Chao; Sun, Huan; Zeng, Hong; Yang, Ping

2016-08-01

Phrenic nerve injury and diaphragmatic stimulation are common complications following arrhythmia ablation and pacing therapies. Preoperative comprehension of phrenic nerve anatomy via non-invasive CT imaging may help to minimize the electrophysiological procedure-related complications. Coronary CT angiography data of 121 consecutive patients were collected. Imaging of left and right pericardiophrenic bundles was performed with volume rendering and multi-planar reformation techniques. The shortest spatial distances between phrenic nerves and key electrophysiology-related structures were determined. The frequencies of the shortest distances ≤5 mm, >5 mm and direct contact between phrenic nerves and adjacent structures were calculated. Left and right pericardiophrenic bundles were identified in 86.8% and 51.2% of the patients, respectively. The right phrenic nerve was <5 mm from right superior and inferior pulmonary veins in 92.0% and 3.2% of the patients, respectively. The percentage of right phrenic nerve, <5 mm from right atrium, superior caval vein, and superior caval vein-right atrium junction was 87.1%, 100%, and 62.9%, respectively. Left phrenic nerve was <5 mm from left atrial appendage, great cardiac vein, anterior and posterior interventricular veins, and left ventricular posterior veins in 81.9%, 1.0%, 39.1%, 28.6%, and 91.4% of the patients, respectively. Merely 0.06% left phrenic nerve had a distance <5 mm with left superior pulmonary vein, and none left phrenic nerve showed a distance <5 mm with left inferior pulmonary vein. One-stop enhanced CT scanning enabled detection of phrenic nerve anatomy, which might facilitate avoidance of the phrenic nerve-related complications in interventional electrophysiology. © 2016 Wiley Periodicals, Inc.

PACE: Pharmacists use the power of communication in paediatric asthma.

PubMed

Elaro, Amanda; Shah, Smita; Pomare, Luca N; L Armour, Carol; Z Bosnic-Anticevich, Sinthia

2014-10-01

Paediatric asthma is a public health burden in Australia despite the availability of national asthma guidelines. Community pharmacy interventions focusing on paediatric asthma are scarce. Practitioner Asthma Communication and Education (PACE) is an evidence-based program, developed in the USA for general practice physicians, aimed at addressing the issues of poor clinician-patient communication in the management of paediatric asthma. This program has been shown to improve paediatric asthma management practices of general practitioners in the USA and Australia. The development of a PACE program for community pharmacists will fill a void in the current armamentarium for pharmacist-patient care. To adapt the educational program, PACE, to the community pharmacy setting. To test the feasibility of the new program for pharmacy and to explore its potential impact on pharmacists' communication skills and asthma related practices. Community pharmacies located within the Sydney metropolitan. The PACE framework was reviewed by the research team and amended in order to ensure its relevance within the pharmacy context, thereby developing PACE for Pharmacy. Forty-four pharmacists were recruited and trained in small groups in the PACE for Pharmacy workshops. Pharmacists' satisfaction and acceptability of the workshops, confidence in using communication strategies pre- and post-workshop and self-reported behaviour change post workshop were evaluated. Pharmacist self-reported changes in communication and teaching behaviours during a paediatric asthma consultation. All 44 pharmacists attended both workshops, completed pre- and post-workshop questionnaires and provided feedback on the workshops (100 % retention). The participants reported a high level of satisfaction and valued the interactive nature of the workshops. Following the PACE for Pharmacy program, pharmacists reported significantly higher levels in using the communication strategies, confidence in their application and their helpfulness. Pharmacists checked for written asthma self-management plan possession and inhaler device technique more regularly, and provided verbal instructions more frequently to paediatric asthma patients/carers at the initiation of a new medication. This study provides preliminary evidence that the PACE program can be translated into community pharmacy. PACE for Pharmacy positively affected self-reported communication and education behaviours of pharmacists. The high response rate shows that pharmacists are eager to expand on their clinical role in primary healthcare.

R&D on Composition and Processing of Titanium Aluminide Alloys for Turbine Engines

DTIC Science & Technology

1982-07-01

45433. AUTHORITY AFWAL ltr, 6 Feb 1987 THIS PAGE IS UNCLASSIFIED AFWAL-TR-82-4086 R&D ON COMPOSITION AND PROCESSING4 OF TITANIUM ALUMINIDE ALLOYS FOR...TR-82-4086- 4. TITLE (and Subitfle) S TYPE OF REPORT I PERIOO COVEREO R&D ON COMPOSITION AND PROCESSING OF Interim Technical Report TITANIUM ALUMINIDE ...ILLUSTRATIONS FICURE PACE 1 As-received titanium aluminide ingots supplied 9 by RMI. (a) S/N 20007; (b) left to right, S/N 20008, S/N 20009, S/N 20010

Efficacy of Precordial Percussion Pacing Assessed in a Cardiac Standstill Microminipig Model.

PubMed

Wada, Takeshi; Ohara, Hiroshi; Nakamura, Yuji; Cao, Xin; Izumi-Nakaseko, Hiroko; Ando, Kentaro; Honda, Mitsuru; Yoshihara, Katsunori; Nakazato, Yuji; Lurie, Keith G; Sugiyama, Atsushi

2017-07-25

Potential cardiovascular benefits of precordial percussion pacing (PPP) during cardiac standstill are unknown.Methods and Results:A cardiac standstill model in amicrominipigwas created by inducing complete atrioventricular block with a catheter ablation technique (n=7). Next, the efficacy of cardiopulmonary resuscitation by standard chest compressions (S-CPR), PPP and ventricular electrical pacing in this model were analyzed in series (n=4). To assess the mechanism of PPP, a non-selective, stretch-activated channel blocker, amiloride, was administered during PPP (n=3). Peak systolic and diastolic arterial pressures during S-CPR, PPP and ventricular electrical pacing were statistically similar. However, the duration of developed arterial pressure with PPP was comparable to that with ventricular electrical pacing, and significantly greater than that with S-CPR. Amiloride decreased the induction rate of ventricular electrical activity by PPP in a dose-related manner. Each animal survived without any neurological deficit at 24, 48 h and 1 week, even with up to 2 h of continuous PPP. In amicrominipigmodel of cardiac standstill, PPP can become a novel means to significantly improve physiological outcomes after cardiac standstill or symptomatic bradyarrhythmias in the absence of cardiac pacing. Activation of the non-selective stretch-activated channels may mediate some of the mechanophysiological effects of PPP. Further study of PPP by itself and together with S-CPR is warranted using cardiac arrest models of atrioventricular block and asystole.

Evaluation and "PACE": A Study of Procedures and Effectiveness of Evaluation Sections in Approved PACE Project, with Recommendations for Improvement.

ERIC Educational Resources Information Center

Miller, Richard I.

This report is based upon an analysis of the evaluation procedures outlined in 21 funded Title III proposals. The proposals were analyzed from a number of points of view. (1) Using the Stufflabeam model as a guide, they were examined to determine what, if any, provisions had been made for each of the four classes of evaluation: context, input,…

Triggered intracellular calcium waves in dog and human left atrial myocytes from normal and failing hearts.

PubMed

Aistrup, Gary L; Arora, Rishi; Grubb, Søren; Yoo, Shin; Toren, Benjamin; Kumar, Manvinder; Kunamalla, Aaron; Marszalec, William; Motiwala, Tej; Tai, Shannon; Yamakawa, Sean; Yerrabolu, Satya; Alvarado, Francisco J; Valdivia, Hector H; Cordeiro, Jonathan M; Shiferaw, Yohannes; Wasserstrom, John Andrew

2017-11-01

Abnormal intracellular Ca2+ cycling contributes to triggered activity and arrhythmias in the heart. We investigated the properties and underlying mechanisms for systolic triggered Ca2+ waves in left atria from normal and failing dog hearts. Intracellular Ca2+ cycling was studied using confocal microscopy during rapid pacing of atrial myocytes (36 °C) isolated from normal and failing canine hearts (ventricular tachypacing model). In normal atrial myocytes (NAMs), Ca2+ waves developed during rapid pacing at rates ≥ 3.3 Hz and immediately disappeared upon cessation of pacing despite high sarcoplasmic reticulum (SR) load. In heart failure atrial myocytes (HFAMs), triggered Ca2+ waves (TCWs) developed at a higher incidence at slower rates. Because of their timing, TCW development relies upon action potential (AP)-evoked Ca2+ entry. The distribution of Ca2+ wave latencies indicated two populations of waves, with early events representing TCWs and late events representing conventional spontaneous Ca2+ waves. Latency analysis also demonstrated that TCWs arise after junctional Ca2+ release has occurred and spread to non-junctional (cell core) SR. TCWs also occurred in intact dog atrium and in myocytes from humans and pigs. β-adrenergic stimulation increased Ca2+ release and abolished TCWs in NAMs but was ineffective in HFAMs making this a potentially effective adaptive mechanism in normals but potentially arrhythmogenic in HF. Block of Ca-calmodulin kinase II also abolished TCWs, suggesting a role in TCW formation. Pharmacological manoeuvres that increased Ca2+ release suppressed TCWs as did interventions that decreased Ca2+ release but these also severely reduced excitation-contraction coupling. TCWs develop during the atrial AP and thus could affect AP duration, producing repolarization gradients and creating a substrate for reentry, particularly in HF where they develop at slower rates and a higher incidence. TCWs may represent a mechanism for the initiation of atrial fibrillation particularly in HF. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions please email: journals.permissions@oup.com.

Effects of gastric pacing on gastric emptying and plasma motilin

PubMed Central

Yang, Min; Fang, Dian-Chun; Li, Qian-Wei; Sun, Nian-Xu; Long, Qing-Lin; Sui, Jian-Feng; Gan, Lu

2004-01-01

AIM: To investigate the effects of gastric pacing on gastric emptying and plasma motilin level in a canine model of gastric motility disorders and the correlation between gastric emptying and plasma motilin level. METHODS: Ten healthy Mongrel dogs were divided into: experimental group of six dogs and control group of four dogs. A model of gastric motility disorders was established in the experimental group undergone truncal vagotomy combined with injection of glucagon. Gastric half-emptying time (GEt1/2) was monitored with single photon emission computerized tomography (SPECT), and the half-solid test meal was labeled with an isotope 99mTc sulfur colloid. Plasma motilin concentration was measured with radioimmunoassay (RIA) kit. Surface gastric pacing at 1.1-1.2 times the intrinsic slow-wave frequency and a superimposed series of high frequency pulses (10-30 Hz) was performed for 45 min daily for a month in conscious dogs. RESULTS: After surgery, GEt1/2 in dogs undergone truncal vagotomy was increased significantly from 56.35 ± 2.99 min to 79.42 ± 1.91 min (P < 0.001), but surface gastric pacing markedly accelerated gastric emptying and significantly decreased GEt1/2 to 64.94 ± 1.75 min (P < 0.001) in animals undergone vagotomy. There was a significant increase of plasma level of motilin at the phase of IMCIII (interdigestive myoelectrical complex, IMCIII) in the dogs undergone bilateral truncal vagotomy (baseline vs vagotomy, 184.29 ± 9.81 pg/ml vs 242.09 ± 17.22 pg/ml; P < 0.01). But plasma motilin concentration (212.55 ± 11.20 pg/ml; P < 0.02) was decreased significantly after a long-term treatment with gastric pacing. Before gastric pacing, GEt1/2 and plasma motilin concentration of the dogs undergone vagotomy showed a positive correlation (r = 0.867, P < 0.01), but after a long-term gastric pacing, GEt1/2 and motilin level showed a negative correlation (r = -0.733, P < 0.04). CONCLUSION: Surface gastric pacing with optimal pacing parameters can improve gastric emptying parameters and significantly accelerate gastric emptying and can resume or alter motor function in a canine model of motility disorders. Gastric emptying is correlated well with plasma motilin level before and after pacing, which suggests that motilin can modulate the mechanism of gastric pacing by altering gastric motility. PMID:14760770

Study protocol for improving asthma outcomes through cross-cultural communication training for physicians: a randomized trial of physician training.

PubMed

Patel, Minal R; Thomas, Lara J; Hafeez, Kausar; Shankin, Matthew; Wilkin, Margaret; Brown, Randall W

2014-06-16

Massive resources are expended every year on cross-cultural communication training for physicians. Such training is a focus of continuing medical education nationwide and is part of the curriculum of virtually every medical school in America. There is a pressing need for evidence regarding the effects on patients of cross-cultural communication training for physicians. There is a need to understand the added benefit of such training compared to more general communication. We know of no rigorous study that has assessed whether cross-cultural communication training for physicians results in better health outcomes for their patients. The current study aims to answer this question by enhancing the Physician Asthma Care Education (PACE) program to cross cultural communication (PACE Plus), and comparing the effect of the enhanced program to PACE on the health outcomes of African American and Latino/Hispanic children with asthma. A three-arm randomized control trial is used to compare PACE Plus, PACE, and usual care. Both PACE and PACE Plus are delivered in two, two-hour sessions over a period of two weeks to 5-10 primary care physicians who treat African American and Latino/Hispanic children with asthma. One hundred twelve physicians and 1060 of their pediatric patients were recruited who self-identify as African American or Latino/Hispanic and experience persistent asthma. Physicians were randomized into receiving either the PACE Plus or PACE intervention or into the control group. The comparative effectiveness of PACE and PACE Plus on clinician's therapeutic and communication practices with the family/patient, children's urgent care use for asthma, asthma control, and quality of life, and parent/caretaker satisfaction with physician performance will be assessed. Data are collected via telephone survey and medical record review at baseline, 9 months following the intervention, and 21 months following the intervention. This study aims to reduce disparities in asthma outcomes among African American and Latino/Hispanic children through cross-cultural communication training of their physicians and assessing the added value of this training compared to general communication. The results of this study will provide important information about the value of cross-cultural training in helping to address persistent racial disparities in outcomes. ClinicalTrials.gov: NCT01251523 December 1, 2010.

[Permanent cardiac pacing for chronic symptomatic atrioventricular block in uremic hemodialysed patients. A prospective study].

PubMed

Arsenescu, Cătălina; Georgescu, G I M; Covic, A; Briotă, Laura

2002-01-01

Though sudden cardiac death accounts for as much as 15% of all cause mortality in uremia, reports concerning advanced A-V block, requiring permanent cardiac pacing in end-stage renal disease (ESRD) hemodialysed (HD) patients are very few. This is the first long term prospective study reporting on systematic permanent pacemaker implantation, in a cohort of ESRD patients from a single HD unit. Between 01/06/1997 and 30/12/2001, 396 pacemakers were inserted for advanced, symptomatic A-V block in our institution, including 5 in ESRD, HD patients (M/F--4/1, age 47-73, M +/- SD--61 +/- 12 years) from a single dialysis center, treating 137 patients during the study period. Thus, the incidence and prevalence of A-V defects treated by permanent pacing in uremic patients was 0.81% and 3.65% respectively. Conversely, the incidence and prevalence of ESRD treated by hemodialysis, among patients with advanced A-V conduction disturbances, requiring permanent pacing were 0.28% and 1.26%. Mitral valve calcifications were present in all patients; 3 subjects also had extensive aortic valve calcifications. Left ventricular hypertrophy (echocardiographic Framingham criteria) was present in 4 patients, but the systolic function (ejection fraction and fractional shortening index) was normal in all cases, although a clinical picture of chronic heart failure was seen in 3 subjects preoperatively. A-V conduction defects were attributed to extensive metastatic calcifications, involving the cardiac squeleton, consecutive to severe hyperparathyroidism and inadvertent use of calcitriol and calcium carbonate as phosphate binders. No technical difficulties, short or long-term complications related to pacemaker implantation (4 VVI and 1 VVD devices) were encountered. Acute threshold and sensing values were similar with those of non-uremic patients. During follow-up, one patients died from a non cardiac death. If optimal hemodialysis is provided, benefits of permanent pacing are equal in uremic or non uremic patients and pacemaker implantation should be instituted as a prompt life-saving method in all dialysis patients with chronic symptomatic advanced A-V blocks.

The Relationship of Walking Intensity to Total and Cause-Specific Mortality. Results from the National Walkers’ Health Study

PubMed Central

Williams, Paul T.; Thompson, Paul D.

2013-01-01

Purpose Test whether: 1) walking intensity predicts mortality when adjusted for walking energy expenditure, and 2) slow walking pace (≥24-minute mile) identifies subjects at substantially elevated risk for mortality. Methods Hazard ratios from Cox proportional survival analyses of all-cause and cause-specific mortality vs. usual walking pace (min/mile) in 7,374 male and 31,607 female recreational walkers. Survival times were left censored for age at entry into the study. Other causes of death were treated as a competing risk for the analyses of cause-specific mortality. All analyses were adjusted for sex, education, baseline smoking, prior heart attack, aspirin use, diet, BMI, and walking energy expenditure. Deaths within one year of baseline were excluded. Results The National Death Index identified 1968 deaths during the average 9.4-year mortality surveillance. Each additional minute per mile in walking pace was associated with an increased risk of mortality due to all causes (1.8% increase, P=10-5), cardiovascular diseases (2.4% increase, P=0.001, 637 deaths), ischemic heart disease (2.8% increase, P=0.003, 336 deaths), heart failure (6.5% increase, P=0.001, 36 deaths), hypertensive heart disease (6.2% increase, P=0.01, 31 deaths), diabetes (6.3% increase, P=0.004, 32 deaths), and dementia (6.6% increase, P=0.0004, 44 deaths). Those reporting a pace slower than a 24-minute mile were at increased risk for mortality due to all-causes (44.3% increased risk, P=0.0001), cardiovascular diseases (43.9% increased risk, P=0.03), and dementia (5.0-fold increased risk, P=0.0002) even though they satisfied the current exercise recommendations by walking ≥7.5 metabolic equivalent (MET)-hours per week. Conclusions The risk for mortality: 1) decreases in association with walking intensity, and 2) increases substantially in association for walking pace ≥24 minute mile (equivalent to <400m during a six-minute walk test) even among subjects who exercise regularly. PMID:24260542

[Coronary revascularization in patients with preoperative electrical storm].

PubMed

Kawashima, Toshiya; Naraoka, S

2007-03-01

We report 5 cases who underwent surgical coronary revascularization for subacute myocardial ischemia with preoperative electrical storm. All patients showed severe left ventricular dysfunction. Mean ejection fraction was 24.4 +/- 7.6%. Three patients had already had implantable cardioverter-defibrillator (ICD) therapy. Procedures were on-pump coronary artery bypass grafting (CABG) and mitral valvuloplasty (MVP) [case 1], on-pump CABG, MVP, left ventricular restoration (LVR) and cryoablation (case 2), and off-pump CABG (case 3-5). Case 5 necessitated conversion to on-pump for electrical storm during left circumflex artery (LCx) anastomosis. Case 3 suddenly died on the 2nd postoperative day due to electrical storm. Case 1 had recurrent attack of electrical storm postoperatively, treated by ICD, overdrive pacing, repeated intraaortic balloon pumping (IABP), deep sedation with endotracheal intubation, and finally catheter ablation. Four patients have survived 2 years (mean) postoperatively without any arrhythmia, and are all in good condition [New York Heart Association (NYHA) I] now. It was concluded that off-pump procedure was not suitable for subacute myocardial ischemia with electrical storm and that LVR with surgical cryoablation would be effective if indicated.

Abnormal brain function in neuromyelitis optica: A fMRI investigation of mPASAT.

PubMed

Wang, Fei; Liu, Yaou; Li, Jianjun; Sondag, Matthew; Law, Meng; Zee, Chi-Shing; Dong, Huiqing; Li, Kuncheng

2017-10-01

Cognitive impairment with the Neuromyelitis Optica (NMO) patients is debated. The present study is to study patterns of brain activation in NMO patients during a pair of task-related fMRI. We studied 20 patients with NMO and 20 control subjects matched for age, gender, education and handedness. All patients with NMO met the 2006 Wingerchuk diagnostic criteria. The fMRI paradigm included an auditory attention monitoring task and a modified version of the Paced Auditory Serial Addition Task (mPASAT). Both tasks were temporally and spatially balanced, with the exception of task difficulty. In mPASAT, Activation regions in control subjects included bilateral superior temporal gyri (BA22), left inferior frontal gyrus (BA45), bilateral inferior parietal lobule (BA7), left cingulate gyrus (BA32), left insula (BA13), and cerebellum. Activation regions in NMO patients included bilateral superior temporal gyri (BA22), left inferior frontal gyrus (BA9), right cingulate gyrus (BA32), right inferior parietal gyrus (BA40), left insula (BA13) and cerebellum. Some dispersed cognition related regions are greater in the patients. The present study showed altered cerebral activation during mPASAT in patients with NMO relative to healthy controls. These results are speculated to provide further evidence for brain plasticity in patients with NMO. Copyright © 2017 Elsevier B.V. All rights reserved.

Phase mapping of radionuclide gated biventriculograms in patients with sustained ventricular tachycardia or Wolff-Parkinson-White syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Guludec, D.; Bourguignon, M.; Sebag, C.

1987-01-01

Accuracy of Fourier phase mapping of radionuclide gated biventriculograms in detecting the origin of abnormal ventricular activation was studied during ventricular tachycardia or preexcitation. Group I included six patients suffering from clinical recurrent VT; 3 gated blood pool studies were acquired for each patient: during sinus rhythm, right ventricular pacing, and induced sustained VT-Group II included seven patients with Wolff-Parkinson-White syndrome and recurrent paroxysmal tachycardia; 3 gated blood pool studies were acquired for each patient: during sinus rhythm, right atrial pacing and orthodromic reciprocating tachycardia. Each acquisition lasted 5 min, in 30 degrees-40 degrees left anterior oblique projection. In Groupmore » I, the Fourier phase mapping was consistent with QRS morphology and axis during VT (5/6), except in one patient with LV aneurysm and LBBB electrical pattern during VT. Origin of VT on phase mapping was located in the right ventricle (n = 2) or in left ventricle (n = 4), at the border of wall motion abnormalities each time they existed (5/6). In Group II, the phase advance correlated with the location of the accessory pathway determined by ECG and endocardial mapping (n = 6) and per-operative epicardial mapping (n = 1). Discrimination between anterior and posterior localization of paraseptal pathways and location of intermittent preexcitation was not possible. We conclude that Fourier phase mapping is an accurate method for locating the origin of VT and determining its etiology. It can help locate the site of ventricular preexcitation in patients with only one accessory pathway; its accuracy in locating multiple accessory pathways remains unknown.« less

Correlation of mitochondrial protein expression in complexes I to V with natural and induced forms of canine idiopathic dilated cardiomyopathy.

PubMed

Lopes, Rosana; Solter, Philip F; Sisson, D David; Oyama, Mark A; Prosek, Robert

2006-06-01

To identify qualitative and quantitative differences in cardiac mitochondrial protein expression in complexes I to V between healthy dogs and dogs with natural or induced dilated cardiomyopathy (DCM). Left ventricle samples were obtained from 7 healthy dogs, 7 Doberman Pinschers with naturally occurring DCM, and 7 dogs with DCM induced by rapid right ventricular pacing. Fresh and frozen mitochondrial fractions were isolated from the left ventricular free wall and analyzed by 2-dimensional electrophoresis. Protein spots that increased or decreased in density by 2-fold or greater between groups were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometry. A total of 22 altered mitochondrial proteins were identified in complexes I to V. Ten and 12 were found in complex I and complexes II to V, respectively. Five were mitochondrial encoded, and 17 were nuclear encoded. Most altered mitochondrial proteins in tissue specimens from dogs with naturally occurring DCM were associated with complexes I and V, whereas in tissue specimens from dogs subjected to rapid ventricular pacing, complexes I and IV were more affected. In the experimentally induced form of DCM, only nuclear-encoded subunits were changed in complex I. In both disease groups, the 22-kd subunit was downregulated. Natural and induced forms of DCM resulted in altered mitochondrial protein expression in complexes I to V. However, subcellular differences between the experimental and naturally occurring forms of DCM may exist.

Isolation of canine coronary sinus musculature from the atria by radiofrequency catheter ablation prevents induction of atrial fibrillation.

PubMed

Morita, Hiroshi; Zipes, Douglas P; Morita, Shiho T; Wu, Jiashin

2014-12-01

The junction between the coronary sinus (CS) musculature and both atria contributes to initiation of atrial tachyarrhythmias. The current study investigated the effects of CS isolation from the atria by radiofrequency catheter ablation on the induction and maintenance of atrial fibrillation (AF). Using an optical mapping system, we mapped action potentials at 256 surface sites in 17 isolated and arterially perfused canine atrial tissues containing the entire musculature of the CS, right atrial septum, posterior left atrium, left inferior pulmonary vein, and vein of Marshal. Rapid pacing from each site before and after addition of acetylcholine (0.5 μmol/L) was applied to induce AF. Epicardial radiofrequency catheter ablation at CS-atrial junctions isolated the CS from the atria. Rapid pacing induced sustained AF in all tissues after acetylcholine. Microreentry within the CS drove AF in 88% of preparations. Reentries associated with the vein of Marshall (29%), CS-atrial junctions (53%), right atrium (65%), and pulmonary vein (76%) (frequently with 2-4 simultaneous circuits) were additional drivers of AF. Radiofrequency catheter ablation eliminated AF in 13 tissues before acetylcholine (P<0.01) and in 5 tissues after acetylcholine. Radiofrequency catheter ablation also abbreviated the duration of AF in 12 tissues (P<0.01). CS and its musculature developed unstable reentry and AF, which were prevented by isolation of CS musculature from atrial tissue. The results suggest that CS can be a substrate of recurrent AF in patients after pulmonary vein isolation and that CS isolation might help prevent recurrent AF. © 2014 American Heart Association, Inc.

Effect of horizontal pick and place locations on shoulder kinematics.

PubMed

Könemann, R; Bosch, T; Kingma, I; Van Dieën, J H; De Looze, M P

2015-01-01

In this study the effects of horizontal bin locations in an order picking workstation on upper arm elevation, trunk inclination and hand use were investigated. Eight subjects moved (self-paced) light or heavy products (0.2 and 3.0 kg) from a central product bin to an inner or outer order bin (at 60 or 150 cm) on the left or right side of the workstation, while movements were recorded. The outer compared to inner bin location resulted in more upper arm elevation and trunk inclination per work cycle, both in terms of number of peak values and in terms of time integrals of angles (which is a dose measure over time). Considering the peak values and time integrals per minute (instead of per work cycle), these effects are reduced, due to the higher cycle times for outer bins. Hand use (left, right or both) was not affected by order bin locations.

Noninvasive imaging of three-dimensional cardiac activation sequence during pacing and ventricular tachycardia.

PubMed

Han, Chengzong; Pogwizd, Steven M; Killingsworth, Cheryl R; He, Bin

2011-08-01

Imaging cardiac excitation within ventricular myocardium is important in the treatment of cardiac arrhythmias and might help improve our understanding of arrhythmia mechanisms. This study sought to rigorously assess the imaging performance of a 3-dimensional (3D) cardiac electrical imaging (3DCEI) technique with the aid of 3D intracardiac mapping from up to 216 intramural sites during paced rhythm and norepinephrine (NE)-induced ventricular tachycardia (VT) in the rabbit heart. Body surface potentials and intramural bipolar electrical recordings were simultaneously measured in a closed-chest condition in 13 healthy rabbits. Single-site pacing and dual-site pacing were performed from ventricular walls and septum. VTs and premature ventricular complexes (PVCs) were induced by intravenous NE. Computed tomography images were obtained to construct geometry models. The noninvasively imaged activation sequence correlated well with invasively measured counterpart, with a correlation coefficient of 0.72 ± 0.04, and a relative error of 0.30 ± 0.02 averaged over 520 paced beats as well as 73 NE-induced PVCs and VT beats. All PVCs and VT beats initiated in the subendocardium by a nonreentrant mechanism. The averaged distance from the imaged site of initial activation to the pacing site or site of arrhythmias determined from intracardiac mapping was ∼5 mm. For dual-site pacing, the double origins were identified when they were located at contralateral sides of ventricles or at the lateral wall and the apex. 3DCEI can noninvasively delineate important features of focal or multifocal ventricular excitation. It offers the potential to aid in localizing the origins and imaging activation sequences of ventricular arrhythmias, and to provide noninvasive assessment of the underlying arrhythmia mechanisms. Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Noninvasive Imaging of Three-dimensional Cardiac Activation Sequence during Pacing and Ventricular Tachycardia

PubMed Central

Han, Chengzong; Pogwizd, Steven M.; Killingsworth, Cheryl R.; He, Bin

2011-01-01

Background Imaging cardiac excitation within ventricular myocardium is important in the treatment of cardiac arrhythmias and might help improve our understanding of arrhythmia mechanisms. Objective This study aims to rigorously assess the imaging performance of a three-dimensional (3-D) cardiac electrical imaging (3-DCEI) technique with the aid of 3-D intra-cardiac mapping from up to 216 intramural sites during paced rhythm and norepinephrine (NE) induced ventricular tachycardia (VT) in the rabbit heart. Methods Body surface potentials and intramural bipolar electrical recordings were simultaneously measured in a closed-chest condition in thirteen healthy rabbits. Single-site pacing and dual-site pacing were performed from ventricular walls and septum. VTs and premature ventricular complexes (PVCs) were induced by intravenous NE. Computer tomography images were obtained to construct geometry model. Results The non-invasively imaged activation sequence correlated well with invasively measured counterparts, with a correlation coefficient of 0.72±0.04, and a relative error of 0.30±0.02 averaged over 520 paced beats as well as 73 NE-induced PVCs and VT beats. All PVCs and VT beats initiated in the subendocardium by a nonreentrant mechanism. The averaged distance from imaged site of initial activation to pacing site or site of arrhythmias determined from intra-cardiac mapping was ~5mm. For dual-site pacing, the double origins were identified when they were located at contralateral sides of ventricles or at the lateral wall and the apex. Conclusion 3-DCEI can non-invasively delineate important features of focal or multi-focal ventricular excitation. It offers the potential to aid in localizing the origins and imaging activation sequence of ventricular arrhythmias, and to provide noninvasive assessment of the underlying arrhythmia mechanisms. PMID:21397046

Remodelling of cardiac sympathetic re-innervation with thoracic spinal cord stimulation improves left ventricular function in a porcine model of heart failure.

PubMed

Liao, Song-Yan; Liu, Yuan; Zuo, Mingliang; Zhang, Yuelin; Yue, Wensheng; Au, Ka-Wing; Lai, Wing-Hon; Wu, Yangsong; Shuto, Chika; Chen, Peter; Siu, Chung-Wah; Schwartz, Peter J; Tse, Hung-Fat

2015-12-01

Thoracic spinal cord stimulation (SCS) has been shown to improve left ventricular ejection fraction (LVEF) in heart failure (HF). Nevertheless, the optimal duration (intermittent vs. continuous) of stimulation and the mechanisms of action remain unclear. We performed chronic thoracic SCS at the level of T1-T3 (50 Hz, pulse width 0.2 ms) in 30 adult pigs with HF induced by myocardial infarction and rapid ventricular pacing for 4 weeks. All the animals were treated with daily oral metoprolol succinate (25 mg) plus ramipril (2.5 mg), and randomized to a control group (n = 10), intermittent SCS (4 h ×3, n = 10) or continuous SCS (24 h, n = 10) for 10 weeks. Serial measurements of LVEF and +dP/dt and serum levels of norepinephrine and B-type natriuretic peptide (BNP) were measured. After sacrifice, immunohistological studies of myocardial sympathetic and parasympathetic nerve sprouting and innervation were performed. Echocardiogram revealed a significant increase in LVEF and +dP/dt at 10 weeks in both the intermittent and continuous SCS group compared with controls (P < 0.05). In both SCS groups, there was diffuse sympathetic nerve sprouting over the infarct, peri-infarct, and normal regions compared with only the peri-infarct and infarct regions in the control group. In addition, sympathetic innervation at the peri-infarct and infarct regions was increased following SCS, but decreased in the control group. Myocardium norepinephrine spillover and serum BNP at 10 weeks was significantly decreased only in the continuous SCS group (P < 0.05). In a porcine model of HF, SCS induces significant remodelling of cardiac sympathetic innervation over the peri-infarct and infarct regions and is associated with improved LV function and reduced myocardial norepinephrine spillover. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Giant cell myocarditis with cardiac tamponade: a rare combination.

PubMed

Murty, O P

2008-09-01

Giant cell myocarditis (GCM) is a rare but fatal disease of idiopathic origin. It results in focal necrosis of myocardium. This is a case report of middle aged Malaysian Indian female who died due to cardiac tamponade due to rupture myocardium and tear in the root of aorta. On naked eye examination, it simply resembled as recent as well as old fibrotic areas of myocardial infarction. She was clinically diagnosed as a case of obstructive cardiomyopathy with atrioventricular block, and was on pace maker. There was subendocardial fibrosis and left ventricular transmural infarction in the left ventricle. On histopathology, this was diagnosed as GCM, there were widespread areas of inflammatory cellular infiltration within the myocardium with multinucleated giant cells and granulomas interspersed with lymphocytes. Microscopic field showed up to 10 multinucleated giant cells. In this case, there were focal areas at multiple locations and caused uneven thickness in the left ventricle wall. Idiopathic GCM is very rare and causation of hemopericardium is the unique feature of this case. In this case the direct link of GCM with aortitis and rupture of left ventricle wall resulting in hemopericardium is shown. This case is documented through macroscopic as well as microscopic photographs in H&E, Ziel-Nelson, and GMS staining.

Pajarito Aerosol Couplings to Ecosystems (PACE) Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubey, M

Laboratory (LANL) worked on the Pajarito Aerosol Couplings to Ecosystems (PACE) intensive operational period (IOP). PACE’s primary goal was to demonstrate routine Mobile Aerosol Observing System (MAOS) field operations and improve instrumental and operational performance. LANL operated the instruments efficiently and effectively with remote guidance by the instrument mentors. This was the first time a complex suite of instruments had been operated under the ARM model and it proved to be a very successful and cost-effective model to build upon.

42 CFR 460.136 - Internal quality assessment and performance improvement activities.

Code of Federal Regulations, 2014 CFR

2014-10-01

... in quality assessment and performance improvement activities, including providing information about... 42 Public Health 4 2014-10-01 2014-10-01 false Internal quality assessment and performance...) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460...

42 CFR 460.136 - Internal quality assessment and performance improvement activities.

Code of Federal Regulations, 2012 CFR

2012-10-01

... in quality assessment and performance improvement activities, including providing information about... 42 Public Health 4 2012-10-01 2012-10-01 false Internal quality assessment and performance...) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460...

42 CFR 460.136 - Internal quality assessment and performance improvement activities.

Code of Federal Regulations, 2013 CFR

2013-10-01

... in quality assessment and performance improvement activities, including providing information about... 42 Public Health 4 2013-10-01 2013-10-01 false Internal quality assessment and performance...) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460...

Outcomes following kinesthetic feedback for gait training in a direct access environment: a case report on social wellness in relation to gait impairment.

PubMed

Blievernicht, Jessica; Sullivan, Kate; Erickson, Mark R

2012-05-01

The purpose of this case report was to describe the outcomes following the use of kinesthetic feedback as a primary intervention strategy for gait training. The plan of care for this 22-year-old female addressed the patient's social wellness goal of "walking more normally," using motor learning principles. At initial examination, the patient demonstrated asymmetries for gait kinematics between the left and right lower extremity (analyzed using video motion analysis), pattern of force distribution at the foot, and activation of specific lower extremity muscles (as measured by surface electromyography). Interventions for this patient consisted of neuromuscular and body awareness training, with an emphasis on kinesthetic feedback. Weekly sessions lasted 30-60 minutes over 4 weeks. The patient was prescribed a home program of walking 30-60 minutes three times/week at a comfortable pace while concentrating on gait correction through kinesthetic awareness of specific deviations. Following intervention, the patient's gait improved across all objective measures. She reported receiving positive comments from others regarding improved gait and a twofold increase in her walking confidence. Outcomes support a broadened scope of practice that incorporates previously unreported integration of a patient's social wellness goals into patient management.

Effects of self-paced interval and continuous training on health markers in women.

PubMed

Connolly, Luke J; Bailey, Stephen J; Krustrup, Peter; Fulford, Jonathan; Smietanka, Chris; Jones, Andrew M

2017-11-01

To compare the effects of self-paced high-intensity interval and continuous cycle training on health markers in premenopausal women. Forty-five inactive females were randomised to a high-intensity interval training (HIIT; n = 15), continuous training (CT; n = 15) or an inactive control (CON; n = 15) group. HIIT performed 5 × 5 min sets comprising repetitions of 30-s low-, 20-s moderate- and 10-s high-intensity cycling with 2 min rest between sets. CT completed 50 min of continuous cycling. Training was completed self-paced, 3 times weekly for 12 weeks. Peak oxygen uptake (16 ± 8 and 21 ± 12%), resting heart rate (HR) (-5 ± 9 and -4 ± 7 bpm) and visual and verbal learning improved following HIIT and CT compared to CON (P < 0.05). Total body mass (-0.7 ± 1.4 kg), submaximal walking HR (-3 ± 4 bpm) and verbal memory were enhanced following HIIT (P < 0.05), whereas mental well-being, systolic (-5 ± 6 mmHg) and mean arterial (-3 ± 5 mmHg) blood pressures were improved following CT (P < 0.05). Participants reported similar levels of enjoyment following HIIT and CT, and there were no changes in fasting serum lipids, fasting blood [glucose] or [glucose] during an oral glucose tolerance test following either HIIT or CT (P > 0.05). No outcome variable changed in the CON group (P > 0.05). Twelve weeks of self-paced HIIT and CT were similarly effective at improving cardiorespiratory fitness, resting HR and cognitive function in inactive premenopausal women, whereas blood pressure, submaximal HR, well-being and body mass adaptations were training-type-specific. Both training methods improved established health markers, but the adaptations to HIIT were evoked for a lower time commitment.

Effects of aging on control of timing and force of finger tapping.

PubMed

Sasaki, Hirokazu; Masumoto, Junya; Inui, Nobuyuki

2011-04-01

The present study examined whether the elderly produced a hastened or delayed tap with a negative or positive constant intertap interval error more frequently in self-paced tapping than in the stimulus-synchronized tapping for the 2 N target force at 2 or 4 Hz frequency. The analysis showed that, at both frequencies, the percentage of the delayed tap was larger in the self-paced tapping than in the stimulus-synchronized tapping, whereas the hastened tap showed the opposite result. At the 4 Hz frequency, all age groups had more variable intertap intervals during the self-paced tapping than during the stimulus-synchronized tapping, and the variability of the intertap intervals increased with age. Thus, although the increase in the frequency of delayed taps and variable intertap intervals in the self-paced tapping perhaps resulted from a dysfunction of movement timing in the basal ganglia with age, the decline in timing accuracy was somewhat improved by an auditory cue. The force variability of tapping at 4 Hz further increased with age, indicating an effect of aging on the control of force.

Self-Paced Prioritized Curriculum Learning With Coverage Penalty in Deep Reinforcement Learning.

PubMed

Ren, Zhipeng; Dong, Daoyi; Li, Huaxiong; Chen, Chunlin; Zhipeng Ren; Daoyi Dong; Huaxiong Li; Chunlin Chen; Dong, Daoyi; Li, Huaxiong; Chen, Chunlin; Ren, Zhipeng

2018-06-01

In this paper, a new training paradigm is proposed for deep reinforcement learning using self-paced prioritized curriculum learning with coverage penalty. The proposed deep curriculum reinforcement learning (DCRL) takes the most advantage of experience replay by adaptively selecting appropriate transitions from replay memory based on the complexity of each transition. The criteria of complexity in DCRL consist of self-paced priority as well as coverage penalty. The self-paced priority reflects the relationship between the temporal-difference error and the difficulty of the current curriculum for sample efficiency. The coverage penalty is taken into account for sample diversity. With comparison to deep Q network (DQN) and prioritized experience replay (PER) methods, the DCRL algorithm is evaluated on Atari 2600 games, and the experimental results show that DCRL outperforms DQN and PER on most of these games. More results further show that the proposed curriculum training paradigm of DCRL is also applicable and effective for other memory-based deep reinforcement learning approaches, such as double DQN and dueling network. All the experimental results demonstrate that DCRL can achieve improved training efficiency and robustness for deep reinforcement learning.

Paced respiration with end-expiration technique offers superior BOLD signal repeatability for breath-hold studies.

PubMed

Scouten, A; Schwarzbauer, C

2008-11-01

As a simple, non-invasive method of blood oxygenation level-dependent (BOLD) signal calibration, the breath-hold task offers considerable potential for the quantification of neuronal activity from functional magnetic resonance imaging (fMRI) measurements. With an aim to improve the precision of this calibration method, the impact of respiratory rate control on the BOLD signal achieved with the breath-hold task was investigated. In addition to self-paced breathing, three different computer-paced breathing rates were imposed during the periods between end-expiration breath-hold blocks. The resulting BOLD signal timecourses and statistical activation maps were compared in eleven healthy human subjects. Results indicate that computer-paced respiration produces a larger peak BOLD signal increase with breath-hold than self-paced breathing, in addition to lower variability between trials. This is due to the more significant post-breath-hold signal undershoot present in self-paced runs, a characteristic which confounds the definition of baseline and is difficult to accurately model. Interestingly, the specific respiratory rate imposed between breath-hold periods generally does not have a statistically significant impact on the BOLD signal change. This result can be explained by previous reports of humans adjusting their inhalation depth to compensate for changes in rate, with the end-goal of maintaining homeostatic ventilation. The advantage of using end-expiration relative to end-inspiration breath-hold is apparent in view of the high repeatability of the BOLD signal in the present study, which does not suffer from the previously reported high variability associated with uncontrolled inspiration depth when using the end-inspiration technique.

Rhythm perturbations in acoustically paced treadmill walking after stroke.

PubMed

Roerdink, Melvyn; Lamoth, Claudine J C; van Kordelaar, Joost; Elich, Peter; Konijnenbelt, Manin; Kwakkel, Gert; Beek, Peter J

2009-09-01

In rehabilitation, acoustic rhythms are often used to improve gait after stroke. Acoustic cueing may enhance gait coordination by creating a stable coupling between heel strikes and metronome beats and provide a means to train the adaptability of gait coordination to environmental changes, as required in everyday life ambulation. To examine the stability and adaptability of auditory-motor synchronization in acoustically paced treadmill walking in stroke patients. Eleven stroke patients and 10 healthy controls walked on a treadmill at preferred speed and cadence under no metronome, single-metronome (pacing only paretic or nonparetic steps), and double-metronome (pacing both footfalls) conditions. The stability of auditory-motor synchronization was quantified by the variability of the phase relation between footfalls and beats. In a separate session, the acoustic rhythms were perturbed and adaptations to restore auditory-motor synchronization were quantified. For both groups, auditory-motor synchronization was more stable for double-metronome than single-metronome conditions, with stroke patients exhibiting an overall weaker coupling of footfalls to metronome beats than controls. The recovery characteristics following rhythm perturbations corroborated the stability findings and further revealed that stroke patients had difficulty in accelerating their steps and instead preferred a slower-step response to restore synchronization. In gait rehabilitation practice, the use of acoustic rhythms may be more effective when both footfalls are paced. In addition, rhythm perturbations during acoustically paced treadmill walking may not only be employed to evaluate the stability of auditory-motor synchronization but also have promising implications for evaluation and training of gait adaptations in neurorehabilitation practice.

42 CFR 460.138 - Committees with community input.

Code of Federal Regulations, 2014 CFR

2014-10-01

... FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.138 Committees with... following: (a) Evaluate data collected pertaining to quality outcome measures. (b) Address the implementation of, and results from, the quality assessment and performance improvement plan. (c) Provide input...

42 CFR 460.138 - Committees with community input.

Code of Federal Regulations, 2013 CFR

2013-10-01

... FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.138 Committees with... following: (a) Evaluate data collected pertaining to quality outcome measures. (b) Address the implementation of, and results from, the quality assessment and performance improvement plan. (c) Provide input...

42 CFR 460.138 - Committees with community input.

Code of Federal Regulations, 2010 CFR

2010-10-01

... FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.138 Committees with... following: (a) Evaluate data collected pertaining to quality outcome measures. (b) Address the implementation of, and results from, the quality assessment and performance improvement plan. (c) Provide input...

42 CFR 460.138 - Committees with community input.

Code of Federal Regulations, 2012 CFR

2012-10-01

... FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.138 Committees with... following: (a) Evaluate data collected pertaining to quality outcome measures. (b) Address the implementation of, and results from, the quality assessment and performance improvement plan. (c) Provide input...

42 CFR 460.138 - Committees with community input.

Code of Federal Regulations, 2011 CFR

2011-10-01

... FOR THE ELDERLY (PACE) Quality Assessment and Performance Improvement § 460.138 Committees with... following: (a) Evaluate data collected pertaining to quality outcome measures. (b) Address the implementation of, and results from, the quality assessment and performance improvement plan. (c) Provide input...

The quantitative assessment of epicardial fat distribution on human hearts: Implications for epicardial electrophysiology.

PubMed

Mattson, Alexander R; Soto, Mario J; Iaizzo, Paul A

2018-07-01

Epicardial electrophysiological procedures rely on dependable interfacing with the myocardial tissue. For example, epicardial pacing systems must generate sustainable chronic pacing capture, while epicardial ablations must effectively deliver energy to the target hyper-excitable myocytes. The human heart has a significant adipose layer which may impede epicardial procedures. The objective of this study was to quantitatively assess the relative location of epicardial adipose on the human heart, to define locations where epicardial therapies might be performed successfully. We studied perfusion-fixed human hearts (n = 105) in multiple isolated planes including: left ventricular margin, diaphragmatic surface, and anterior right ventricle. Relative adipose distribution was quantitatively assessed via planar images, using a custom-generated image analysis algorithm. In these specimens, 76.7 ± 13.8% of the left ventricular margin, 72.7 ± 11.3% of the diaphragmatic surface, and 92.1 ± 8.7% of the anterior right margin were covered with superficial epicardial adipose layers. Percent adipose coverage significantly increased with age (P < 0.001) and history of coronary artery disease (P < 0.05). No significant relationships were identified between relative percent adipose coverage and gender, body weight or height, BMI, history of hypertension, and/or history of congestive heart failure. Additionally, we describe two-dimensional probability distributions of epicardial adipose coverage for each of the three analysis planes. In this study, we detail the quantitative assessment and probabilistic mapping of the distribution of superficial epicardial adipose on the adult human heart. These findings have implications relative to performing epicardial procedures and/or designing procedures or tools to successfully perform such treatments. Clin. Anat. 31:661-666, 2018. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Local transmural action potential gradients are absent in the isolated, intact dog heart but present in the corresponding coronary-perfused wedge.

PubMed

Boukens, Bastiaan J; Meijborg, Veronique M F; Belterman, Charly N; Opthof, Tobias; Janse, Michiel J; Schuessler, Richard B; Coronel, Ruben; Efimov, Igor R

2017-05-01

The left ventricular (LV) coronary-perfused canine wedge preparation is a model commonly used for studying cardiac repolarization. In wedge studies, transmembrane potentials typically are recorded; whereas, extracellular electrical recordings are commonly used in intact hearts. We compared electrically measured activation recovery interval (ARI) patterns in the intact heart with those recorded at the same location in the LV wedge preparation. We also compared electrically recorded and optically obtained ARIs in the LV wedge preparation. Five Langendorff-perfused canine hearts were paced from the right atrium. Local activation and repolarization times were measured with eight transmural needle electrodes. Subsequently, left ventricular coronary-perfused wedge preparations were prepared from these hearts while the electrodes remained in place. Three electrodes remained at identical positions as in the intact heart. Both electrograms and optical action potentials were recorded (pacing cycle length 400-4000 msec) and activation and repolarization patterns were analyzed. ARIs found in the subepicardium were shorter than in the subendocardium in the LV wedge preparation but not in the intact heart. The transmural ARI gradient recorded at the cut surface of the wedge was not different from that recorded internally. ARIs recorded internally and at the cut surface in the LV wedge preparation, both correlated with optically recorded action potentials. ARI and RT gradients in the LV wedge preparation differed from those in the intact canine heart, implying that those observations in human LV wedge preparations also should be extrapolated to the intact human heart with caution. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Novel approach to epicardial pacemaker implantation in patients with limited venous access.

PubMed

Costa, Roberto; Scanavacca, Mauricio; da Silva, Kátia Regina; Martinelli Filho, Martino; Carrillo, Roger

2013-11-01

Limited venous access in certain patients increases the procedural risk and complexity of conventional transvenous pacemaker implantation. The purpose of this study was to determine a minimally invasive epicardial approach using pericardial reflections for dual-chamber pacemaker implantation in patients with limited venous access. Between June 2006 and November 2011, 15 patients underwent epicardial pacemaker implantation. Procedures were performed through a minimally invasive subxiphoid approach and pericardial window with subsequent fluoroscopy-assisted lead placement. Mean patient age was 46.4 ± 15.3 years (9 male [(60.0%], 6 female [40.0%]). The new surgical approach was used in patients determined to have limited venous access due to multiple abandoned leads in 5 (33.3%), venous occlusion in 3 (20.0%), intravascular retention of lead fragments from prior extraction in 3 (20.0%), tricuspid valve vegetation currently under treatment in 2 (13.3%), and unrepaired intracardiac defects in 2 (13.3%). All procedures were successful with no perioperative complications or early deaths. Mean operating time for isolated pacemaker implantation was 231.7 ± 33.5 minutes. Lead placement on the superior aspect of right atrium, through the transverse sinus, was possible in 12 patients. In the remaining 3 patients, the atrial lead was implanted on the left atrium through the oblique sinus, the postcaval recess, or the left pulmonary vein recess. None of the patients displayed pacing or sensing dysfunction, and all parameters remained stable throughout the follow-up period of 36.8 ± 25.1 months. Epicardial pacemaker implantation through pericardial reflections is an effective alternative therapy for those patients requiring physiologic pacing in whom venous access is limited. © 2013 Heart Rhythm Society. All rights reserved.

Age-related changes in the bimanual advantage and in brain oscillatory activity during tapping movements suggest a decline in processing sensory reafference.

PubMed

Sallard, Etienne; Spierer, Lucas; Ludwig, Catherine; Deiber, Marie-Pierre; Barral, Jérôme

2014-02-01

Deficits in the processing of sensory reafferences have been suggested as accounting for age-related decline in motor coordination. Whether sensory reafferences are accurately processed can be assessed based on the bimanual advantage in tapping: because of tapping with an additional hand increases kinesthetic reafferences, bimanual tapping is characterized by a reduced inter-tap interval variability than unimanual tapping. A suppression of the bimanual advantage would thus indicate a deficit in sensory reafference. We tested whether elderly indeed show a reduced bimanual advantage by measuring unimanual (UM) and bimanual (BM) self-paced tapping performance in groups of young (n = 29) and old (n = 27) healthy adults. Electroencephalogram was recorded to assess the underlying patterns of oscillatory activity, a neurophysiological mechanism advanced to support the integration of sensory reafferences. Behaviorally, there was a significant interaction between the factors tapping condition and age group at the level of the inter-tap interval variability, driven by a lower variability in BM than UM tapping in the young, but not in the elderly group. This result indicates that in self-paced tapping, the bimanual advantage is absent in elderly. Electrophysiological results revealed an interaction between tapping condition and age group on low beta band (14-20 Hz) activity. Beta activity varied depending on the tapping condition in the elderly but not in the young group. Source estimations localized this effect within left superior parietal and left occipital areas. We interpret our results in terms of engagement of different mechanisms in the elderly depending on the tapping mode: a 'kinesthetic' mechanism for UM and a 'visual imagery' mechanism for BM tapping movement.

Catheter-Based Renal Sympathetic Denervation Significantly Inhibits Atrial Fibrillation Induced by Electrical Stimulation of the Left Stellate Ganglion and Rapid Atrial Pacing

PubMed Central

Po, Sunny S.; Wang, Huan; Zhang, Ling; Zhang, Feng; Wang, Kun; Zhou, Qina

2013-01-01

Background Sympathetic activity involves the pathogenesis of atrial fibrillation (AF). Renal sympathetic denervation (RSD) decreases sympathetic renal afferent nerve activity, leading to decreased central sympathetic drive. The aim of this study was to identify the effects of RSD on AF inducibility induced by hyper-sympathetic activity in a canine model. Methods To establish a hyper-sympathetic tone canine model of AF, sixteen dogs were subjected to stimulation of left stellate ganglion (LSG) and rapid atrial pacing (RAP) for 3 hours. Then animals in the RSD group (n = 8) underwent radiofrequency ablation of the renal sympathetic nerve. The control group (n = 8) underwent the same procedure except for ablation. AF inducibility, effective refractory period (ERP), ERP dispersion, heart rate variability and plasma norepinephrine levels were measured at baseline, after stimulation and after ablation. Results LSG stimulation combined RAP significantly induced higher AF induction rate, shorter ERP, larger ERP dispersion at all sites examined and higher plasma norepinephrine levels (P<0.05 in all values), compared to baseline. The increased AF induction rate, shortened ERP, increased ERP dispersion and elevated plasma norepinephrine levels can be almost reversed by RSD, compared to the control group (P<0.05). LSG stimulation combined RAP markedly shortened RR-interval and standard deviation of all RR-intervals (SDNN), Low-frequency (LF), high-frequency (HF) and LF/HF ratio (P<0.05). These changes can be reversed by RSD, compared to the control group (P<0.05). Conclusions RSD significantly reduced AF inducibility and reversed the atrial electrophysiological changes induced by hyper-sympathetic activity. PMID:24223140

Frequency-dependent left ventricular performance in women and men.

PubMed

Wainstein, Rodrigo V; Sasson, Zion; Mak, Susanna

2012-06-01

We aimed to determine whether sex differences in humans extend to the dynamic response of the left ventricular (LV) chamber to changes in heart rate (HR). Several observations suggest sex influences LV structure and function in health; moreover, this physiology is also affected in a sex-specific manner by aging. Eight postmenopausal women and eight similarly aged men underwent a cardiac catheterization-based study for force-interval relationships of the LV. HR was controlled by right atrial (RA) pacing, and LV +dP/dt(max) and volume were assessed by micromanometer-tipped catheter and Doppler echocardiography, respectively. Analysis of approximated LV pressure-volume relationships was performed using a time-varying model of elastance. External stroke work was also calculated. The relationship between HR and LV +dP/dt(max) was expressed as LV +dP/dt(max) = b + mHR. The slope (m) of the relationship was steeper in women compared with men (11.8 ± 4.0 vs. 6.1 ± 4.1 mmHg·s(-1)·beats(-1)·min(-1), P = 0.01). The greater increase in contractility in women was reproducibly observed after normalizing LV +dP/dt(max) to LV end-diastolic volume (LVVed) or by measuring end-systolic elastance. LVVed and stroke volume decreased more in women. Thus, despite greater increases in contractility, HR was associated with a lesser rise in cardiac output and a steeper fall in external stroke work in women. Compared with men, women exhibit greater inotropic responses to incremental RA pacing, which occurs at the same time as a steeper decline in external stroke work. In older adults, we observed sexual dimorphism in determinants of LV mechanical performance.

Variability of coronary venous anatomy in patients undergoing cardiac resynchronization therapy: a high-speed rotational venography study.

PubMed

Blendea, Dan; Shah, Ravi V; Auricchio, Angelo; Nandigam, Veena; Orencole, Mary; Heist, E Kevin; Reddy, Vivek Y; McPherson, Craig A; Ruskin, Jeremy N; Singh, Jagmeet P

2007-09-01

Imaging the coronary venous (CV) tree to delineate the coronary sinus and its tributaries can facilitate electrophysiological procedures, such as cardiac resynchronization therapy (CRT) and catheter ablation. Venography also allows visualization of the left atrial (LA) veins, which may be a potential conduit for ablative or pacing strategies given their proximity to foci that can trigger atrial fibrillation. The aim of this study was to provide a detailed description of CV anatomy using rotational venography in patients undergoing CRT. Coronary sinus (CS) size and the presence, size, and angulation of its tributaries were determined from the analysis of rotational CV angiograms from 51 patients (age 68 +/- 11 years; n = 12 women) undergoing CRT. The CS, posterior veins, and lateral veins were identified in 100%, 76%, and 91% of patients. Lateral veins were less prevalent in patients with a history of lateral myocardial infarction than in patients without such a history (33% vs. 96%; P = .014). The diameters of the CS and its tributaries were fairly variable (7.3-18.9 mm for CS, 1.3-10.5 mm for CS tributaries). The CS was larger in men than in women and in cases of ischemic than in cases of nonischemic cardiomyopathy (all P <.05). The vein of Marshall, the most constant LA vein, was identified in 37 patients; its diameter is 1.7 +/- 0.5 mm, and its takeoff angle is 154 degrees +/- 15 degrees , making the vein potentially accessible for cannulation. Differences in CV anatomy that are related to either gender or coronary artery disease could have important practical implications during the left ventricular lead implantation. The anatomical features of the vein of Marshall make it a feasible potential conduit for epicardial LA pacing.

Toward a More Efficient Implementation of Antifibrillation Pacing

PubMed Central

Wilson, Dan; Moehlis, Jeff

2016-01-01

We devise a methodology to determine an optimal pattern of inputs to synchronize firing patterns of cardiac cells which only requires the ability to measure action potential durations in individual cells. In numerical bidomain simulations, the resulting synchronizing inputs are shown to terminate spiral waves with a higher probability than comparable inputs that do not synchronize the cells as strongly. These results suggest that designing stimuli which promote synchronization in cardiac tissue could improve the success rate of defibrillation, and point towards novel strategies for optimizing antifibrillation pacing. PMID:27391010

Performance of dedicated versus integrated bipolar defibrillator leads with CRT-defibrillators: results from a Prospective Multicenter Study.

PubMed

Freedman, Roger A; Petrakian, Alex; Boyce, Ker; Haffajee, Charles; Val-Mejias, Jesus E; Oza, Ashish L

2009-02-01

Right ventricular (RV) anodal stimulation may occur in cardiac resynchronization therapy defibrillators (CRT-D) when left ventricular (LV) pacing is configured between the LV lead and an electrode on the RV defibrillator lead. RV defibrillator leads can have a dedicated proximal pacing ring electrode (dedicated bipolar) or utilize the distal shocking coil as the proximal pacing electrode (integrated bipolar). This study compares the performance of integrated versus dedicated leads with respect to anodal stimulation incidence, sensing, and inappropriate ventricular tachyarrhythmia detection in patients implanted with CRT-D. Two hundred ninety-two patients were randomly assigned to receive dedicated or integrated bipolar RV leads at the time of CRT-D implantation. Patients were followed for 6 months. Patients with dedicated bipolar RV leads exhibited markedly higher rates of anodal stimulation than did patients with integrated leads. The incidence of anodal stimulation was 64% at implant for dedicated bipolar RV leads compared to 1% for integrated bipolar RV leads. The likelihood of anodal stimulation in patients with dedicated leads fell progressively during the 6-month follow-up (51.5%), but always exceeded the incidence of anodal stimulation in patients with integrated leads (5%). Clinically detectable undersensing and oversensing were very unusual and did not differ significantly between lead designs. There were no inappropriate ventricular tachyarrhythmia detections for either lead type. Integrated bipolar RV defibrillator leads had a significantly lower incidence of RV anodal stimulation when compared to dedicated bipolar RV defibrillation leads, with no clinically detectable oversensing or undersensing, and with no inappropriate ventricular tachyarrhythmia detections for either lead type.

Universal algorithm for diagnosis of biventricular capture in patients with cardiac resynchronization therapy.

PubMed

Jastrzebski, Marek; Kukla, Piotr; Fijorek, Kamil; Czarnecka, Danuta

2014-08-01

An accurate and universal method for diagnosis of biventricular (BiV) capture using a standard 12-lead electrocardiogram (ECG) would be useful for assessment of cardiac resynchronization therapy (CRT) patients. Our objective was to develop and validate such an ECG method for BiV capture diagnosis that would be independent of pacing lead positions-a major confounder that significantly influences the morphologies of paced QRS complexes. On the basis of an evaluation of 789 ECGs of 443 patients with heart failure and various right ventricular (RV) and left ventricular (LV) lead positions, the following algorithm was constructed and validated. BiV capture was diagnosed if the QRS in lead I was predominantly negative and either V1 QRS was predominantly positive or V6 QRS was of negative onset and predominantly negative (step 1), or if QRS complex duration was <160 ms (step 2). All other ECGs were classified as loss of LV capture. The algorithm showed good accuracy (93%), sensitivity (97%), and specificity (90%) for detection of loss of LV capture. The performance of the algorithm did not differ among apical, midseptal, and outflow tract RV lead positions and various LV lead positions. LV capture leaves diagnostic hallmarks in the fused BiV QRS related to different vectors of depolarization and more rapid depolarization of the ventricles. An accurate two-step ECG algorithm for BiV capture diagnosis was developed and validated. This algorithm is universally applicable to all CRT patients, regardless of the positions of the pacing leads. ©2014 Wiley Periodicals, Inc.

Intracellular free calcium concentration measured with /sup 19/F NMR spectroscopy in intact ferret hearts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marban, E.; Kitakaze, M.; Kusuoka, H.

1987-08-01

Changes in the intracellular free Ca/sup 2 +/ concentration, (Ca/sup 2 +/)/sub i/, mediate excitation-contraction coupling in the heart and contribute to cellular injury during ischemia and reperfusion. To study these processes directly, the authors measured (Ca/sup 2 +/)/sub i/ in perfused ferret (Mustela putorius furo) hearts using /sup 19/F NMR spectroscopy to detect the 5,5'-difluoro derivative of the Ca/sup 2 +/ chelator, 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). To load cells, hearts were perfused with the acetoxymethyl ester derivative of 5,5'-F/sub 2/-BAPTA. They measured /sup 19/F NMR spectra and left ventricular pressure simultaneously,at rest and during pacing at various external Ca concentrationsmore » ((Ca)/sub 0/). Although contractile force was attenuated by the Ca/sup 2 +/ buffering properties of 5,5'-F/sup 2/-BAPTA, the decrease in pressure could be overcome by raising (Ca)/sub 0/. The mean value of 104 nM for (Ca/sup 2 +/)/sub i/ at rest in the perfused heart agrees well with previous measurements in isolated ventricular muscle. During pacing at 0.6-4 Hz, time-averaged (Ca/sup 2 +/)/sub i/ increased; the effect of pacing was augmented by increasing (Ca)/sub 0/. (Ca/sup 2 +/)/sub i/ more than tripled during 10-20 min of global ischemia, and returned toward control levels upon reperfusion. This approach promises to be particularly useful in investigating the physiology of intact hearts and the pathophysiology of alterations in the coronary circulation« less

Safety of Magnetic Resonance Imaging in Patients with Cardiac Devices.

PubMed

Nazarian, Saman; Hansford, Rozann; Rahsepar, Amir A; Weltin, Valeria; McVeigh, Diana; Gucuk Ipek, Esra; Kwan, Alan; Berger, Ronald D; Calkins, Hugh; Lardo, Albert C; Kraut, Michael A; Kamel, Ihab R; Zimmerman, Stefan L; Halperin, Henry R

2017-12-28

Patients who have pacemakers or defibrillators are often denied the opportunity to undergo magnetic resonance imaging (MRI) because of safety concerns, unless the devices meet certain criteria specified by the Food and Drug Administration (termed "MRI-conditional" devices). We performed a prospective, nonrandomized study to assess the safety of MRI at a magnetic field strength of 1.5 Tesla in 1509 patients who had a pacemaker (58%) or an implantable cardioverter-defibrillator (42%) that was not considered to be MRI-conditional (termed a "legacy" device). Overall, the patients underwent 2103 thoracic and nonthoracic MRI examinations that were deemed to be clinically necessary. The pacing mode was changed to asynchronous mode for pacing-dependent patients and to demand mode for other patients. Tachyarrhythmia functions were disabled. Outcome assessments included adverse events and changes in the variables that indicate lead and generator function and interaction with surrounding tissue (device parameters). No long-term clinically significant adverse events were reported. In nine MRI examinations (0.4%; 95% confidence interval, 0.2 to 0.7), the patient's device reset to a backup mode. The reset was transient in eight of the nine examinations. In one case, a pacemaker with less than 1 month left of battery life reset to ventricular inhibited pacing and could not be reprogrammed; the device was subsequently replaced. The most common notable change in device parameters (>50% change from baseline) immediately after MRI was a decrease in P-wave amplitude, which occurred in 1% of the patients. At long-term follow-up (results of which were available for 63% of the patients), the most common notable changes from baseline were decreases in P-wave amplitude (in 4% of the patients), increases in atrial capture threshold (4%), increases in right ventricular capture threshold (4%), and increases in left ventricular capture threshold (3%). The observed changes in lead parameters were not clinically significant and did not require device revision or reprogramming. We evaluated the safety of MRI, performed with the use of a prespecified safety protocol, in 1509 patients who had a legacy pacemaker or a legacy implantable cardioverter-defibrillator system. No long-term clinically significant adverse events were reported. (Funded by Johns Hopkins University and the National Institutes of Health; ClinicalTrials.gov number, NCT01130896 .).

The influence of a 12% carbohydrate-electrolyte beverage on self-paced soccer-specific exercise performance.

PubMed

Harper, Liam D; Stevenson, Emma J; Rollo, Ian; Russell, Mark

2017-12-01

To assess the physiological and performance effects of a 12% carbohydrate-electrolyte beverage consumed at practically applicable time-points (i.e., before each half) throughout simulated soccer match-play. Randomised, counterbalanced, crossover. Fed players (n=15) performed 90-min of soccer-specific exercise (including self-paced exercise at the end of each half). Players consumed carbohydrate-electrolyte (CHO; 60g×500ml -1 , Na + 205mg×500ml -1 ), placebo-electrolyte (PL) or water (Wat) beverages at the end of the warm-up (250ml) and half-time (250ml plus ad-libitum water). Blood was drawn before each half and every 15-min during exercise. Physical (15-m sprinting, countermovement jumps, self-paced distance, acceleration/deceleration count), technical (dribbling) and cognitive (memory, attention, decision-making) performance was assessed. Ratings of perceived exertion (RPE) and abdominal discomfort were measured. Against Wat and PL, CHO increased (all p<0.05) mean accelerations >1.5m·s -2 during self-paced exercise (>+25%) and dribbling speed from 60-min onwards (>+3%). Mean sprinting speed improved (+2.7%) in CHO versus Wat. Blood glucose increased before and during each half in CHO versus PL and Wat (all p<0.05). A 27% decline in glycaemia occurred at 60-min in CHO. RPE was comparable between trials. Cognition reduced post-exercise (p<0.05); this decline was not attenuated by CHO. Abdominal discomfort increased during exercise but was similar between trials. Using more realistic fluid ingestion timings than have been examined previously, consuming a 12% carbohydrate-electrolyte beverage increased blood glucose, self-paced exercise performance, and improved dribbling speed in the final 30-min of exercise compared to water and placebo. Carbohydrates did not attenuate post-exercise reductions in cognition. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Atrial overexpression of angiotensin-converting enzyme 2 improves the canine rapid atrial pacing-induced structural and electrical remodeling. Fan, ACE2 improves atrial substrate remodeling.

PubMed

Fan, Jinqi; Zou, Lili; Cui, Kun; Woo, Kamsang; Du, Huaan; Chen, Shaojie; Ling, Zhiyu; Zhang, Quanjun; Zhang, Bo; Lan, Xianbin; Su, Li; Zrenner, Bernhard; Yin, Yuehui

2015-01-01

The purpose of this study was to investigate whether atrial overexpression of angiotensin-converting enzyme 2 (ACE2) by homogeneous transmural atrial gene transfer can reverse atrial remodeling and its mechanisms in a canine atrial-pacing model. Twenty-eight mongrel dogs were randomly divided into four groups: Sham-operated, AF-control, gene therapy with adenovirus-enhanced green fluorescent protein (Ad-EGFP) and gene therapy with Ad-ACE2 (Ad-ACE2) (n = 7 per subgroup). AF was induced in all dogs except the Sham-operated group by rapid atrial pacing at 450 beats/min for 2 weeks. Ad-EGFP and Ad-ACE2 group then received epicardial gene painting. Three weeks after gene transfer, all animals except the Sham group underwent rapid atrial pacing for another 3 weeks and then invasive electrophysiological, histological and molecular studies. The Ad-ACE2 group showed an increased ACE2 and Angiotensin-(1-7) expression, and decreased Angiotensin II expression in comparison with Ad-EGFP and AF-control group. ACE2 overexpression attenuated rapid atrial pacing-induced increase in activated extracellular signal-regulated kinases and mitogen-activated protein kinases (MAPKs) levels, and decrease in MAPK phosphatase 1(MKP-1) level, resulting in attenuation of atrial fibrosis collagen protein markers and transforming growth factor-β1. Additionally, ACE2 overexpression also modulated the tachypacing-induced up-regulation of connexin 40, down-regulation of connexin 43 and Kv4.2, and significantly decreased the inducibility and duration of AF. ACE2 overexpression could shift the renin-angiotensin system balance towards the protective axis, attenuate cardiac fibrosis remodeling associated with up-regulation of MKP-1 and reduction of MAPKs activities, modulate tachypacing-induced ion channels and connexin remodeling, and subsequently reduce the inducibility and duration of AF.

Atrial Septopulmonary Bundle of the Posterior Left Atrium Provides a Substrate for Atrial Fibrillation Initiation in a Model of Vagally Mediated Pulmonary Vein Tachycardia of the Structurally Normal Heart

PubMed Central

Klos, Matthew; Calvo, David; Yamazaki, Masatoshi; Zlochiver, Sharon; Mironov, Sergey; Cabrera, José-Angel; Sanchez-Quintana, Damian; Jalife, José; Berenfeld, Omer; Kalifa, Jérôme

2009-01-01

Background The posterior left atrium (PLA) and pulmonary veins (PVs) have been shown to be critical for atrial fibrillation (AF) initiation. However, the detailed mechanisms of reentry and AF initiation by PV impulses are poorly understood. We hypothesized that PV impulses trigger reentry and AF by undergoing wavebreaks as a result of sink-to-source mismatch at specific PV-PLA transitions along the septopulmonary bundle, where there are changes in thickness and fiber direction. Methods and Results In 7 Langendorff-perfused sheep hearts AF was initiated by a burst of 6 pulses (CL 80 to 150ms) delivered to the left inferior or right superior PV ostium 100 to 150 ms after the sinus impulse in the presence of 0.5 μmol/L acetylcholine. The exposed septal-PLA endocardial area was mapped with high spatio-temporal resolution (DI-4-ANEPPS, 1000-fr/s) during AF initiation. Isochronal maps for each paced beat preceding AF onset were constructed to localize areas of conduction delay and block. Phase movies allowed the determination of the wavebreak sites at the onset of AF. Thereafter, the PLA myocardial wall thickness was quantified by echocardiography, and the fiber direction in the optical field of view was determined after peeling off the endocardium. Finally, isochrone, phase and conduction velocity maps were superimposed on the corresponding anatomic pictures for each of the 28 episodes of AF initiation. The longest delays of the paced PV impulses, as well as the first wavebreak, occurred at those boundaries along the septopulmonary bundle that showed sharp changes in fiber direction and the largest and most abrupt increase in myocardial thickness. Conclusion Waves propagating from the PVs into the PLA originating from a simulated PV tachycardia triggered reentry and vagally mediated AF by breaking at boundaries along the septopulmonary bundle where abrupt changes in thickness and fiber direction resulted in sink-to-source mismatch and low safety for propagation. PMID:19609369

Plant breeding for harmony between agriculture and the environment

USDA-ARS?s Scientific Manuscript database

Crop improvements made since the 1950’s coupled with inexpensive agronomic inputs (fertilizers, herbicides, etc.) have resulted in agricultural production that has kept pace with population growth. Breeding programs primarily focus on improving a crop’s environmental adaptability and biotic stress t...

Presentation Time Concerning System-Paced Multimedia Instructions and the Superiority of Learner Pacing

ERIC Educational Resources Information Center

Stiller, Klaus D.; Petzold, Kirstin; Zinnbauer, Peter

2011-01-01

The superiority of learner-paced over system-paced instructions was demonstrated in multiple experiments. In these experiments, the system-paced presentations were highly speeded, causing cognitive overload, while the learner-paced instructions allowed adjustments of the presentational flow to the learner's needs by pacing facilities, mostly…

Hyperconnectivity of the dorsolateral prefrontal cortex following mental effort in multiple sclerosis patients with cognitive fatigue.

PubMed

Pravatà, Emanuele; Zecca, Chiara; Sestieri, Carlo; Caulo, Massimo; Riccitelli, Gianna Carla; Rocca, Maria Assunta; Filippi, Massimo; Cianfoni, Alessandro; Gobbi, Claudio

2016-11-01

To investigate the dynamic temporal changes of brain resting-state functional connectivity (RS-FC) following mental effort in multiple sclerosis (MS) patients with cognitive fatigue (CF). Twenty-two MS patients, 11 with (F) and 11 without CF, and 12 healthy controls were included. Separate RS-FC scans were acquired on a 3T MR scanner immediately before (t0), immediately after (t1) and 30 minutes after (t2) execution of the paced auditory serial addition test (PASAT), a cognitively demanding task. Subjectively perceived CF after PASAT execution was also assessed. RS-FC changes were investigated by using a data-driven approach (the Intrinsic Connectivity Contrast -power ), complemented by a priori defined regions of interest analyses. The F-group patients experienced stronger RS-FC at t2 between the left superior frontal gyrus (L-SFG) and occipital, frontal and temporal areas, which increased over time after PASAT execution. In the F-group patients, the L-SFG was hyperconnected at t1 with the left caudate nucleus and hypoconnected at t2 with the left anterior thalamus. These variations were correlated with both subjectively perceived and clinically assessed CF, and-for the left thalamus-with PASAT performance. The development of cortico-cortical and cortico-subcortical hyperconnectivity following mental effort is related to CF symptoms in MS patients. © The Author(s), 2016.

To create or to recall? Neural mechanisms underlying the generation of creative new ideas☆

PubMed Central

Benedek, Mathias; Jauk, Emanuel; Fink, Andreas; Koschutnig, Karl; Reishofer, Gernot; Ebner, Franz; Neubauer, Aljoscha C.

2014-01-01

This fMRI study investigated brain activation during creative idea generation using a novel approach allowing spontaneous self-paced generation and expression of ideas. Specifically, we addressed the fundamental question of what brain processes are relevant for the generation of genuinely new creative ideas, in contrast to the mere recollection of old ideas from memory. In general, creative idea generation (i.e., divergent thinking) was associated with extended activations in the left prefrontal cortex and the right medial temporal lobe, and with deactivation of the right temporoparietal junction. The generation of new ideas, as opposed to the retrieval of old ideas, was associated with stronger activation in the left inferior parietal cortex which is known to be involved in mental simulation, imagining, and future thought. Moreover, brain activation in the orbital part of the inferior frontal gyrus was found to increase as a function of the creativity (i.e., originality and appropriateness) of ideas pointing to the role of executive processes for overcoming dominant but uncreative responses. We conclude that the process of idea generation can be generally understood as a state of focused internally-directed attention involving controlled semantic retrieval. Moreover, left inferior parietal cortex and left prefrontal regions may subserve the flexible integration of previous knowledge for the construction of new and creative ideas. PMID:24269573

Impairment of Auditory-Motor Timing and Compensatory Reorganization after Ventral Premotor Cortex Stimulation

PubMed Central

Kornysheva, Katja; Schubotz, Ricarda I.

2011-01-01

Integrating auditory and motor information often requires precise timing as in speech and music. In humans, the position of the ventral premotor cortex (PMv) in the dorsal auditory stream renders this area a node for auditory-motor integration. Yet, it remains unknown whether the PMv is critical for auditory-motor timing and which activity increases help to preserve task performance following its disruption. 16 healthy volunteers participated in two sessions with fMRI measured at baseline and following rTMS (rTMS) of either the left PMv or a control region. Subjects synchronized left or right finger tapping to sub-second beat rates of auditory rhythms in the experimental task, and produced self-paced tapping during spectrally matched auditory stimuli in the control task. Left PMv rTMS impaired auditory-motor synchronization accuracy in the first sub-block following stimulation (p<0.01, Bonferroni corrected), but spared motor timing and attention to task. Task-related activity increased in the homologue right PMv, but did not predict the behavioral effect of rTMS. In contrast, anterior midline cerebellum revealed most pronounced activity increase in less impaired subjects. The present findings suggest a critical role of the left PMv in feed-forward computations enabling accurate auditory-motor timing, which can be compensated by activity modulations in the cerebellum, but not in the homologue region contralateral to stimulation. PMID:21738657

First results from the US-PRC PMI collaboration on EAST

NASA Astrophysics Data System (ADS)

Maingi, R.; Lunsford, R.; Mansfield, D.; Diallo, A.; Hu, J.; Sun, Z.; Zuo, G.; Gong, X.; Tritz, K.; Canik, J.; Osborne, T.; EAST Team

2017-10-01

A US-PRC collaboration was formed to understand the plasma-material interface for improved long pulse discharge performance in EAST, with an emphasis on Li conditioning techniques. The US multi-institutional team consists of participants from PPPL, UI-UC, UT-K, ORNL, MIT, LANL, and JHU. In Dec. 2016, this team co-led experiments on the use of Li aerosol injection to mitigate ELMs, Li granule injection to pace ELMs, and a flowing liquid Li limiter to serve as a primary plasma-facing component. Li aerosol injection was shown to eliminate ELMs using the upper ITER-like W divertor, extending previous results of ELM suppression in the lower cabon divertor (J.S. Hu, PRL 2015). In addition Li granule injection was shown to trigger and even pace ELMs, although the paced ELM frequency was slower than the natural ELM frequency in this set of experiments; previously paced ELM frequency was comparable to natural ELMs frequency (D.K. Mansfield, NF 2013). Finally a second generation flowing liquid Li limiter was shown to be compatible with ELMy H-mode plasmas, pushed within 1 cm of the separatrix. The surface showed no damage to PMI and improved wetting as compared to the first generation limiter experiments (J.S. Hu, NF 2016 and G.Z. Zuo, NF 2017). US scientists supported in part by US DoE contracts DE-AC02-09CH11466, DE-FG02-09ER55012, DE-AC05-00OR22725, and DE-FC02-04ER54698, and ASIPP scientists by Contract No. 11625524, No. 11075185, No. 11021565, and No. 2013GB114004.

A wrist tendon travel assessment of hand movements associated with industrial repetitive activities.

PubMed

Ugbolue, U Chris; Nicol, Alexander C

2012-01-01

To investigate slow and fast paced industrial activity hand repetitive movements associated with carpal tunnel syndrome where movements are evaluated based on finger and wrist tendon travel measurements. Nine healthy subjects were recruited for the study aged between 23 and 33 years. Participants mimicked an industrial repetitive task by performing the following activities: wrist flexion and extension task, palm open and close task; and pinch task. Each task was performed for a period of 5 minutes at a slow (0.33 Hz) and fast (1 Hz) pace for a duration of 3 minutes and 2 minutes respectively. Tendon displacement produced higher flexor digitorum superficialis (FDS) tendon travel when compared to the flexor digitorum profundus (FDP) tendons. The left hand mean (SD) tendon travel for the FDS tendon and FDP tendon were 11108 (5188) mm and 9244 (4328) mm while the right hand mean tendon travel (SD) for the FDS tendon and FDP tendon were 9225 (3441) mm and 7670 (2856) mm respectively. Of the three tasks mimicking an industrial repetitive activity, the wrist flexion and extension task produced the most tendon travel. The findings may be useful to researchers in classifying the level of strenuous activity in relation to tendon travel.

Localization of heart vectors produced by epicardial burns and ectopic stimuli; validation of a dipole ranging method.

PubMed

Ideker, R E; Bandura, J P; Larsen, R A; Cox, J W; Keller, F W; Brody, D A

1975-01-01

Location of the equivalent cardiac dipole has been estimated but not fully verified in several laboratories. To test the accuracy of such a procedure, injury vectors were produced in 14 isolated, perfused rabbit hearts by epicardial searing. Strongly dipolar excitation fronts were produced in 6 additional hearts by left ventricular pacing. Twenty computer-processed signals, derived from surface electrodes on a spherical electrolyte-filled tank containing the test preparation, were optimally fitted with a locatable cardiac dipole that accounted for over 99% of the root-mean-square surface potential. For the 14 burns (mean radius 5.0 mm), the S-T injury dipole was located 3.4 plus or minus 0.7 (SD) mm from the burn center. For the 6 paced hearts, the dipole early in the ectopic beat was located 3.7 mm (range 2.6 to 4.6 mm) from the stimulating electrode. Phase inhomogeneities within the chamber appeared to have a small but predictable effect on dipole site determination. The study demonstrates that equivalent dipole location can be determined with acceptable accuracy from potential measurements of the external cardiac field.

An information system that knits the whole company together

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendryx, M.

1997-03-01

During the 1980s, as the economics of the natural gas industry weathered some fairly heavy changes, local distribution companies (LDCs) had to keep pace, with new products and new ways of doing business, or get left behind. The competition for the big industrial and commercial customers became intense, prompting new ventures such as pipeline capacity leases and special industrial sales programs. The transportation business emerged as important in its own right, as profit margins from gas sales shrank; novel provisions in gas purchase contracts became the norm. But in many cases, it was the LDCs` information systems that didn`t keepmore » pace. With business innovations sprouting up like mushrooms, it was hardly surprising that many of the computer applications backing them up emerged as stand-alone operations, designed solely for the business function of one area or department. At Oklahoma Natural Gas Co. the unfortunate consequences of so many new applications separated from one another began to pile up. As the numbers of pipeline-capacity lease and transportation customers continued to expand, the manual effort needed to take care of the requisite paperwork became nearly overwhelming. The paper describes the development of the information system and its operation.« less

Effect on pacemakers of airport weapons detectors

PubMed Central

Johnson, David L.

1974-01-01

An investigation was carried out using a variety of pacemakers and all the types of weapons detectors in common use in Canada, to determine whether or not such detectors present a hazard to pacemaker bearers. The results indicate that only left-side implants of unipolar sensing pacemakers are likely to be affected, that ventricular fibrillation initiated by interference-induced competitive pacing is the only conceivable hazard, but that the probability of 10−9 for the occurrence of this event is so low that it may be completely disregarded. Physicians may therefore reassure pacemaker bearers of their safety in and around airport weapons detectors. ImagesFIG. 1 PMID:4825148

A Multiscale Closed-Loop Cardiovascular Model, with Applications to Heart Pacing and Hemorrhage

NASA Astrophysics Data System (ADS)

Canuto, Daniel; Eldredge, Jeff; Chong, Kwitae; Benharash, Peyman; Dutson, Erik

2017-11-01

A computational tool is developed for simulating the dynamic response of the human cardiovascular system to various stressors and injuries. The tool couples zero-dimensional models of the heart, pulmonary vasculature, and peripheral vasculature to one-dimensional models of the major systemic arteries. To simulate autonomic response, this multiscale circulatory model is integrated with a feedback model of the baroreflex, allowing control of heart rate, cardiac contractility, and peripheral impedance. The performance of the tool is demonstrated in two scenarios: increasing heart rate by stimulating the sympathetic nervous system, and an acute 10 percent hemorrhage from the left femoral artery.

Relationship between mechanical dyssynchrony and intra-operative electrical delay times in patients undergoing cardiac resynchronization therapy

PubMed Central

2014-01-01

Background It is important to understand the relationship between electrical and mechanical ventricular activation in CRT patients. By measuring local electrical activation at multiple locations within the coronary veins and myocardial contraction at the same locations in the left ventricle, we determined the relationship between electrical and mechanical activation at potential left ventricular pacing locations. Methods In this study, mechanical contraction times were computed using high temporal resolution cine cardiovascular magnetic resonance (CMR) data, while electrical activation times were derived from intra-procedural local electrograms. Results In our cohort, there was a strong correlation between electrical and mechanical delay times within each patient (R2 = 0.78 ± 0.23). Additionally, the latest electrically activated location corresponded with the latest mechanically contracting location in 91% of patients. Conclusions This study provides initial evidence that our method of obtaining non-invasive mechanical activation patterns accurately reflects the underlying electromechanical substrate of intraventricular dyssynchrony. PMID:24393383

Accurate means of detecting and characterizing abnormal patterns of ventricular activation by phase image analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Botvinick, E.H.; Frais, M.A.; Shosa, D.W.

1982-08-01

The ability of scintigraphic phase image analysis to characterize patterns of abnormal ventricular activation was investigated. The pattern of phase distribution and sequential phase changes over both right and left ventricular regions of interest were evaluated in 16 patients with normal electrical activation and wall motion and compared with those in 8 patients with an artificial pacemaker and 4 patients with sinus rhythm with the Wolff-Parkinson-White syndrome and delta waves. Normally, the site of earliest phase angle was seen at the base of the interventricular septum, with sequential change affecting the body of the septum and the cardiac apex andmore » then spreading laterally to involve the body of both ventricles. The site of earliest phase angle was located at the apex of the right ventricle in seven patients with a right ventricular endocardial pacemaker and on the lateral left ventricular wall in one patient with a left ventricular epicardial pacemaker. In each case the site corresponded exactly to the position of the pacing electrode as seen on posteroanterior and left lateral chest X-ray films, and sequential phase changes spread from the initial focus to affect both ventricles. In each of the patients with the Wolff-Parkinson-White syndrome, the site of earliest ventricular phase angle was located, and it corresponded exactly to the site of the bypass tract as determined by endocardial mapping. In this way, four bypass pathways, two posterior left paraseptal, one left lateral and one right lateral, were correctly localized scintigraphically. On the basis of the sequence of mechanical contraction, phase image analysis provides an accurate noninvasive method of detecting abnormal foci of ventricular activation.« less

An fMRI study of finger tapping in children and adults.

PubMed

Turesky, Ted K; Olulade, Olumide A; Luetje, Megan M; Eden, Guinevere F

2018-04-02

Functional brain imaging studies have characterized the neural bases of voluntary movement for finger tapping in adults, but equivalent information for children is lacking. When contrasted to adults, one would expect children to have relatively greater activation, reflecting compensation for an underdeveloped motor system combined with less experience in the execution of voluntary movement. To test this hypothesis, we acquired functional magnetic resonance imaging (fMRI) data on 17 healthy right-handed children (7.48 ± 0.66 years) and 15 adults (24.9 ± 2.9 years) while they performed an irregularly paced finger-tapping task in response to a visual cue (left- and right-hand examined separately). Whole-brain within-group analyses revealed that finger tapping in either age group and for either hand activated contralateral SM1, SMA, ipsilateral anterior cerebellum, and occipital cortices. We used an ANOVA factorial design to test for main effects of Age Group (children vs adults), Hand (left vs. right), and their interactions. For main effects of Age Group, children showed relatively greater activity in left SM1 (extending into bilateral SMA), and, surprisingly, adults exhibited relatively greater activity in right pre-SMA/SMA (extending into left pre-SMA/SMA), right lateral globus pallidus, left putamen, and right anterior cerebellum. The interaction of Age Group × Hand revealed that while both groups activated right SM1 during left finger tapping and exhibited signal decreases (i.e., below fixation baseline) during right finger tapping, both these responses were attenuated in children relative to adults. These data provide an important foundation by which to study children with motor disorders. © 2018 Wiley Periodicals, Inc.

Cardiac-resynchronization therapy for mild-to-moderate heart failure.

PubMed

Tang, Anthony S L; Wells, George A; Talajic, Mario; Arnold, Malcolm O; Sheldon, Robert; Connolly, Stuart; Hohnloser, Stefan H; Nichol, Graham; Birnie, David H; Sapp, John L; Yee, Raymond; Healey, Jeffrey S; Rouleau, Jean L

2010-12-16

Cardiac-resynchronization therapy (CRT) benefits patients with left ventricular systolic dysfunction and a wide QRS complex. Most of these patients are candidates for an implantable cardioverter-defibrillator (ICD). We evaluated whether adding CRT to an ICD and optimal medical therapy might reduce mortality and morbidity among such patients. We randomly assigned patients with New York Heart Association (NYHA) class II or III heart failure, a left ventricular ejection fraction of 30% or less, and an intrinsic QRS duration of 120 msec or more or a paced QRS duration of 200 msec or more to receive either an ICD alone or an ICD plus CRT. The primary outcome was death from any cause or hospitalization for heart failure. We followed 1798 patients for a mean of 40 months. The primary outcome occurred in 297 of 894 patients (33.2%) in the ICD-CRT group and 364 of 904 patients (40.3%) in the ICD group (hazard ratio in the ICD-CRT group, 0.75; 95% confidence interval [CI], 0.64 to 0.87; P<0.001). In the ICD-CRT group, 186 patients died, as compared with 236 in the ICD group (hazard ratio, 0.75; 95% CI, 0.62 to 0.91; P = 0.003), and 174 patients were hospitalized for heart failure, as compared with 236 in the ICD group (hazard ratio, 0.68; 95% CI, 0.56 to 0.83; P<0.001). However, at 30 days after device implantation, adverse events had occurred in 124 patients in the ICD-CRT group, as compared with 58 in the ICD group (P<0.001). Among patients with NYHA class II or III heart failure, a wide QRS complex, and left ventricular systolic dysfunction, the addition of CRT to an ICD reduced rates of death and hospitalization for heart failure. This improvement was accompanied by more adverse events. (Funded by the Canadian Institutes of Health Research and Medtronic of Canada; ClinicalTrials.gov number, NCT00251251.).

Selective heart rate reduction with ivabradine slows ischaemia-induced electrophysiological changes and reduces ischaemia–reperfusion-induced ventricular arrhythmias

PubMed Central

Ng, Fu Siong; Shadi, Iqbal T.; Peters, Nicholas S.; Lyon, Alexander R.

2013-01-01

Heart rates during ischaemia and reperfusion are possible determinants of reperfusion arrhythmias. We used ivabradine, a selective If current inhibitor, to assess the effects of heart rate reduction (HRR) during ischaemia–reperfusion on reperfusion ventricular arrhythmias and assessed potential anti-arrhythmic mechanisms by optical mapping. Five groups of rat hearts were subjected to regional ischaemia by left anterior descending artery occlusion for 8 min followed by 10 min of reperfusion: (1) Control n = 10; (2) 1 μM of ivabradine perfusion n = 10; (3) 1 μM of ivabradine + 5 Hz atrial pacing throughout ischaemia–reperfusion n = 5; (4) 1 μM of ivabradine + 5 Hz pacing only at reperfusion; (5) 100 μM of ivabradine was used as a 1 ml bolus upon reperfusion. For optical mapping, 10 hearts (ivabradine n = 5; 5 Hz pacing n = 5) were subjected to global ischaemia whilst transmembrane voltage transients were recorded. Epicardial activation was mapped, and the rate of development of ischaemia-induced electrophysiological changes was assessed. HRR observed in the ivabradine group during both ischaemia (195 ± 11 bpm vs. control 272 ± 14 bpm, p < 0.05) and at reperfusion (168 ± 13 bpm vs. 276 ± 14 bpm, p < 0.05) was associated with reduced reperfusion ventricular fibrillation (VF) incidence (20% vs. 90%, p < 0.05). Pacing throughout ischaemia–reperfusion abolished the protective effects of ivabradine (100% VF), whereas pacing at reperfusion only partially attenuated this effect (40% VF). Ivabradine, given as a bolus at reperfusion, did not significantly affect VF incidence (80% VF). Optical mapping experiments showed a delay to ischaemia-induced conduction slowing (time to 50% conduction slowing: 10.2 ± 1.3 min vs. 5.1 ± 0.7 min, p < 0.05) and to loss of electrical excitability in ivabradine-perfused hearts (27.7 ± 4.3 min vs. 14.5 ± 0.6 min, p < 0.05). Ivabradine administered throughout ischaemia and reperfusion reduced reperfusion VF incidence through HRR. Heart rate during ischaemia is a major determinant of reperfusion arrhythmias. Heart rate at reperfusion alone was not a determinant of reperfusion VF, as neither a bolus of ivabradine nor pacing immediately prior to reperfusion significantly altered reperfusion VF incidence. This anti-arrhythmic effect of heart rate reduction during ischaemia may reflect slower development of ischaemia-induced electrophysiological changes. PMID:23402927

Lost to the NHS: a mixed methods study of why GPs leave practice early in England.

PubMed

Doran, Natasha; Fox, Fiona; Rodham, Karen; Taylor, Gordon; Harris, Michael

2016-02-01

The loss of GPs in the early stages of their careers is contributing to the GP workforce crisis. Recruitment in the UK remains below the numbers needed to support the demand for GP care. To explore the reasons why GPs leave general practice early. A mixed methods study using online survey data triangulated with qualitative interviews. Participants were GPs aged <50 years who had left the English Medical Performers List in the last 5 years (2009-2014). A total of 143 early GP leavers participated in an online survey, of which 21 took part in recorded telephone interviews. Survey data were analysed using descriptive statistics, and qualitative data using thematic analysis techniques. Reasons for leaving were cumulative and multifactorial. Organisational changes to the NHS have led to an increase in administrative tasks and overall workload that is perceived by GP participants to have fundamentally changed the doctor-patient relationship. Lack of time with patients has compromised the ability to practise more patient-centred care, and, with it, GPs' sense of professional autonomy and values, resulting in diminished job satisfaction. In this context, the additional pressures of increased patient demand and the negative media portrayal left many feeling unsupported and vulnerable to burnout and ill health, and, ultimately, to the decision to leave general practice. To improve retention of young GPs, the pace of administrative change needs to be minimised and the time spent by GPs on work that is not face-to-face patient care reduced. © British Journal of General Practice 2016.

Thoracoscopic patch insulation to correct phrenic nerve stimulation secondary to cardiac resynchronization therapy.

PubMed

Mediratta, Neeraj; Barker, Diane; McKevith, James; Davies, Peter; Belchambers, Sandra; Rao, Archana

2012-07-01

Cardiac resynchronization therapy is an established therapy for heart failure, improving quality of life and prognosis. Despite advances in technique, available leads and delivery systems, trans-venous left ventricular (LV) lead positioning remains dependent on the patient's underlying venous anatomy. The left phrenic nerve courses over the surface of the pericardium laterally and may be stimulated by the LV pacing lead, causing uncomfortable diaphragmatic twitch. This paper describes a video-assisted thoracoscopic (VATS) procedure to correct phrenic nerve stimulation secondary to cardiac resynchronization therapy. Most current ways of avoiding phrenic stimulation involve either electronic reprogramming to distance the phrenic nerve from the stimulation circuit or repositioning the lead. We describe a case where the phrenic nerve was surgically insulated from the stimulating current by insinuating a patch of bovine pericardium between the epicardium and native pericardium of the heart thus completely resolving previously intolerable and incessant diaphragmatic twitch. The procedure was performed under general anaesthesia with single-lung ventilation and minimal use of neuromuscular blocking agents. Surgical patch insulation of the phrenic nerve was performed using minimally invasive VATS surgery, as a short-stay procedure, with no complications. No diaphragmatic twitch occurred post-surgery and the patient continued to gain symptomatic benefit from cardiac synchronization therapy (New York Heart Association Class III to II), enabling return to work. In cases where the trans-venous position of a LV lead is limited by troublesome phrenic nerve stimulation, thoracoscopic surgical patch insulation of the phrenic nerve could be considered to allow beneficial cardiac resynchronization therapy.

Simple and conditional visual discrimination with wheel running as reinforcement in rats.

PubMed

Iversen, I H

1998-09-01

Three experiments explored whether access to wheel running is sufficient as reinforcement to establish and maintain simple and conditional visual discriminations in nondeprived rats. In Experiment 1, 2 rats learned to press a lit key to produce access to running; responding was virtually absent when the key was dark, but latencies to respond were longer than for customary food and water reinforcers. Increases in the intertrial interval did not improve the discrimination performance. In Experiment 2, 3 rats acquired a go-left/go-right discrimination with a trial-initiating response and reached an accuracy that exceeded 80%; when two keys showed a steady light, pressing the left key produced access to running whereas pressing the right key produced access to running when both keys showed blinking light. Latencies to respond to the lights shortened when the trial-initiation response was introduced and became much shorter than in Experiment 1. In Experiment 3, 1 rat acquired a conditional discrimination task (matching to sample) with steady versus blinking lights at an accuracy exceeding 80%. A trial-initiation response allowed self-paced trials as in Experiment 2. When the rat was exposed to the task for 19 successive 24-hr periods with access to food and water, the discrimination performance settled in a typical circadian pattern and peak accuracy exceeded 90%. When the trial-initiation response was under extinction, without access to running, the circadian activity pattern determined the time of spontaneous recovery. The experiments demonstrate that wheel-running reinforcement can be used to establish and maintain simple and conditional visual discriminations in nondeprived rats.

Integrating palliative care in long-term care facilities across Europe (PACE): protocol of a cluster randomized controlled trial of the 'PACE Steps to Success' intervention in seven countries.

PubMed

Smets, Tinne; Onwuteaka-Philipsen, Bregje B D; Miranda, Rose; Pivodic, Lara; Tanghe, Marc; van Hout, Hein; Pasman, Roeline H R W; Oosterveld-Vlug, Mariska; Piers, Ruth; Van Den Noortgate, Nele; Wichmann, Anne B; Engels, Yvonne; Vernooij-Dassen, Myrra; Hockley, Jo; Froggatt, Katherine; Payne, Sheila; Szczerbińska, Katarzyna; Kylänen, Marika; Leppäaho, Suvi; Barańska, Ilona; Gambassi, Giovanni; Pautex, Sophie; Bassal, Catherine; Deliens, Luc; Van den Block, Lieve

2018-03-12

Several studies have highlighted the need for improvement in palliative care delivered to older people long-term care facilities. However, the available evidence on how to improve palliative care in these settings is weak, especially in Europe. We describe the protocol of the PACE trial aimed to 1) evaluate the effectiveness and cost-effectiveness of the 'PACE Steps to Success' palliative care intervention for older people in long-term care facilities, and 2) assess the implementation process and identify facilitators and barriers for implementation in different countries. We will conduct a multi-facility cluster randomised controlled trial in Belgium, Finland, Italy, the Netherlands, Poland, Switzerland and England. In total, 72 facilities will be randomized to receive the 'Pace Steps to Success intervention' or to 'care as usual'. Primary outcome at resident level: quality of dying (CAD-EOLD); and at staff level: staff knowledge of palliative care (Palliative Care Survey). resident's quality of end-of-life care, staff self-efficacy, self-perceived educational needs, and opinions on palliative care. Economic outcomes: direct costs and quality-adjusted life years (QALYs). Measurements are performed at baseline and after the intervention. For the resident-level outcomes, facilities report all deaths of residents in and outside the facilities over a previous four-month period and structured questionnaires are sent to (1) the administrator, (2) staff member most involved in care (3) treating general practitioner, and (4) a relative. For the staff-level outcomes, all staff who are working in the facilities are asked to complete a structured questionnaire. A process evaluation will run alongside the effectiveness evaluation in the intervention group using the RE-AIM framework. The lack of high quality trials in palliative care has been recognized throughout the field of palliative care research. This cross-national cluster RCT designed to evaluate the impact of the palliative care intervention for long-term care facilities 'PACE Steps to Success' in seven countries, will provide important evidence concerning the effectiveness as well as the preconditions for optimal implementation of palliative care in nursing homes, and this within different health care systems. The study is registered at www.isrctn.com - ISRCTN14741671 (FP7-HEALTH-2013-INNOVATION-1 603111) Registration date: July 30, 2015.

Report: Progress Made, but Improvements Needed at CTS of Asheville Superfund Site in North Carolina to Advance Cleanup Pace and Reduce Potential Exposure

EPA Pesticide Factsheets

Report #16-P-0296, August 31, 2016. EPA Region 4 can accelerate the cleanup and completeness of work, and improve public communications, to better control human exposure to unsafe industrial contamination at the CTS site.

42 CFR 460.60 - PACE organizational structure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 4 2011-10-01 2011-10-01 false PACE organizational structure. 460.60 Section 460.60 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... ELDERLY (PACE) PACE Administrative Requirements § 460.60 PACE organizational structure. (a) A PACE...

Investigation of mechanisms and non-pharmacological therapy of cardiac arrhythmias

NASA Astrophysics Data System (ADS)

Vago, Hajnalka

Learning of mechanisms of arrhythmias may contribute substantially to the development of effective pharmacological and non-pharmacological therapeutic methods. Clinical relevance of endothelin-1 (ET-1), a strong vasoconstrictor and arrhythmogenic endogenous substrate, is not clarified yet. In our experimental studies, performed in the in situ canine heart, electrophysiological effects and the role in the pathomechanism of malignant ventricular tachyarrhythmias of endogenous and exogenous ET-1 was investigated. It has been proven in the in vivo ischaemia-reperfusion canine heart model, that during reperfusion ET-1 and big-ET levels increase in the coronary sinus, however there was no correlation between endothelin levels and electrophysiological changes. ET A-receptor antagonist darusentan does not prevent electrophysiological changes and development of ventricular tachyarrhythmias during ischaemia and reperfusion. On the contrary, during ischaemia endogenous ET-1 tends to show balancing effect. It has been proven that administration of high dose intracoronary ET-1 bolus has dual, ischaemic and direct, electrophysiological effect. It has been shown for the first time, that ET-1 causes monophasic action potential (MAP) and T-wave alternant. Our clinical study leads to the conclusion that previous atrial fibrillation, absence of preoperative beta-blocker treatment and combined heart surgery are strong predictors of atrial fibrillation following open heart surgery. The basis of new nonpharmacological therapies is the learning of pathomechanisms of arrhythmias and in some cases heart failure, which is an arrhythmogenic substrate. In our experimental study reliable MAP measurements, suitable for investigation of arrhythmogenesis, were performed for the first time using fractally coated ablation catheters during spontaneous rate and during stimulations. It has been proven that radiofrequency ablation affects significantly MAP parameters. In Hungary, we were the first to apply effectively biatrial pacemaker and biatrial cardioverter defibrillator for the prevention of paroxysmal atrial fibrillation. In the majority of patients frequency of paroxysmal atrial fibrillation decreased significantly due to biatrial stimulation or combined pharmacological and resynchronisation therapy. Parasymphathetic cardiac neurostimulation is a promising new non-pharmacological treatment option in certain types of arrhythmias. In our clinical study we were able to stimulate cardiac parasympathetic nerves innervating atrioventricular node achieving ventricular rate control during atrial tachyarrhythmias with chronically implanted coronary sinus lead. In our study biventricular pacemakers and cardioverter defibrillators were applied successfully in the treatment of drug refractory congestive heart failure combined with inter- and/or intraventricular conduction disturbances. AV sequential left sided chronic pacing using a single lead located in the coronary sinus has not been previously reported. Left sided DDD pacing was effective chronically in the improvement of the functional stage of patient suffering from congestive heart disease combined with left bundle branch block and binodal disease. Parallel with the investigation of pathomechanism of life-threatening ventricular tachyarrhythmias and the most common, clinically relevant atrial fibrillation due to recent technical development, we were able to support nonpharmacological therapeutic modalities, gaining popularity in clinical management, with novel observations.

42 CFR 460.6 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis... enrolled in a PACE program. PACE stands for programs of all-inclusive care for the elderly. PACE center is... care for the elderly that is operated by an approved PACE organization and that provides comprehensive...

42 CFR 460.6 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis... enrolled in a PACE program. PACE stands for programs of all-inclusive care for the elderly. PACE center is... care for the elderly that is operated by an approved PACE organization and that provides comprehensive...

42 CFR 460.180 - Medicare payment to PACE organizations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Medicare payment to PACE organizations. 460.180... FOR THE ELDERLY (PACE) Payment § 460.180 Medicare payment to PACE organizations. (a) Principle of payment. Under a PACE program agreement, CMS makes a prospective monthly payment to the PACE organization...

Management and outcome of patients with acute myocardial infarction presenting with pacemaker rhythm.

PubMed

Bertel, Noemi; Witassek, Fabienne; Puhan, Milo; Erne, Paul; Rickli, Hans; Naegeli, Barbara; Pedrazzini, Giovanni; Stauffer, Jean-Christophe; Radovanovic, Dragana

2017-03-01

Diagnosis of acute myocardial infarction (MI) is challenging in pacemaker patients. Little is known about this patient group. Patients with MI enrolled in the Swiss national AMIS Plus registry between January 2005 and December 2015 were analyzed. All patients with either paced ventricular rhythm or sinus rhythm with intrinsic ventricular conduction (IVC) were included in this study. Outcomes using crude data and propensity score matching were compared between patients with pacemaker rhythm and patients with IVC. The primary endpoint was in-hospital death. Data from 300 patients with paced rhythm and 27,595 with IVC were analyzed. Patients with pacemaker rhythm were older (78.2y vs 65.4y; p<0.001), had more comorbidities (Charlson Index (CCI)>1: 54.0% vs 21.1%; p<0.001) and a higher rate of heart failure upon presentation (Killip class>2, 11.0% vs 5.9%; p<0.001) compared to patients with IVC. Door to balloon time in patients undergoing acute PCI is markedly delayed in contrast to patients with IVC (280min vs 85min; p<0.001). Consequently, crude mortality in patients with pacemakers was high (11.3% vs 4.6%; p<0.001). However, when analyzed with propensity matching for gender, age, CCI>1 and Killip>2, mortality was similar (11.2% vs 10.5%; p=0.70). Pacemaker patients with acute MI represent a high-risk group with doubled crude mortality compared to patients without pacemakers, due to higher age and higher Killip class. Diagnosis is difficult and results in delayed treatment. Treatment algorithms for MI with paced rhythm should possibly be adapted to those used for STEMI or new left bundle branch block. NCT01305785. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The pacemaker-twiddler's syndrome: an infrequent cause of pacemaker failure.

PubMed

Salahuddin, Mohammad; Cader, Fathima Aaysha; Nasrin, Sahela; Chowdhury, Mashhud Zia

2016-01-20

The pacemaker-twiddler's syndrome is an uncommon cause of pacemaker malfunction. It occurs due to unintentional or deliberate manipulation of the pacemaker pulse generator within its skin pocket by the patient. This causes coiling of the lead and its dislodgement, resulting in failure of ventricular pacing. More commonly reported among elderly females with impaired cognition, the phenomenon usually occurs in the first year following pacemaker implantation. Treatment involves repositioning of the dislodged leads and suture fixation of the lead and pulse generator within its pocket. An 87 year old Bangladeshi lady who underwent a single chamber ventricular pacemaker (VVI mode: i.e. ventricle paced, ventricle sensed, inhibitory mode) implantation with the indication of complete heart block, and presented to us again 7 weeks later, with syncopal attacks. She admitted to repeatedly manipulating the pacemaker generator in her left pectoral region. Physical examination revealed a heart rate of 42 beats/minute, blood pressure 140/80 mmHg and bilateral crackles on lung auscultation. She had no cognitive deficit. An immediate electrocardiogram showed complete heart block with pacemaker spikes and failure to capture. Chest X-ray showed coiled and retracted right ventricular lead and rotated pulse generator. An emergent temporary pace maker was set at a rate of 60 beats per minute. Subsequently, she underwent successful lead repositioning with strong counselling to avoid further twiddling. Twiddler's syndrome should be considered as a cause of pacemaker failure in elderly patients presenting with bradyarrythmias following pacemaker implantation. Chest X-ray and electrocardiograms are simple and easily-available first line investigations for its diagnosis. Lead repositioning is required, however proper patient education and counselling against further manipulation is paramount to long-term management.

Exaggerated cardiovascular effects of cocaine in conscious dogs with pacing-induced dilated cardiomyopathy.

PubMed

Mathier, Michael A; Shen, You-Tang; Shannon, Richard P

2002-12-01

The aim of this study was to explore the characteristics and mechanisms of the cardiovascular effects of cocaine in dilated cardiomyopathy. We studied the cardiovascular responses to acute intravenous cocaine (1 mg/kg) in 8 conscious, chronically instrumented dogs before and after the development of dilated cardiomyopathy induced by rapid ventricular pacing. To help elucidate the role of altered baroreflex function in mediating the cardiovascular effects of cocaine, we also studied responses in 3 conscious, chronically instrumented dogs that had undergone surgical sinoaortic baroreceptor denervation. Cocaine produced greater increases in heart rate (+57 +/- 8% from 112 +/- 5 beats/min versus +28 +/- 3% from 100 +/- 4 beats/min; P <.01), first derivative of left ventricular pressure (+30 +/- 5% from 1,714 +/- 147 mm Hg/sec versus +15 +/- 3% from 3,032 +/- 199 mm Hg/sec; P <.01), coronary vascular resistance (+28 +/- 5% from 2.3 +/- 0.3 mm Hg/mL/min versus +11 +/- 5% from 2.2 +/- 0.3 mm Hg/mL/min; P <.05) and plasma norepinephrine concentration (+130 +/- 31% from 462 +/- 102 pg/mL versus +86 +/- 32% from 286 +/- 77 pg/mL; P <.05) in dogs with dilated cardiomyopathy as compared to controls. In addition, responses were much more rapid in onset following the development of dilated cardiomyopathy. Chronotropic and inotropic responses to cocaine were similarly rapid and exaggerated in dogs after baroreceptor denervation. Cocaine produces rapid and exaggerated chronotropic, inotropic, and coronary vasoconstrictor responses in conscious dogs with pacing-induced dilated cardiomyopathy. Alterations in arterial baroreflex function may play a role in these observations, which in turn may underlie the clinically observed association between cocaine and heart failure.

Fenofibrate inhibits atrial metabolic remodelling in atrial fibrillation through PPAR-α/sirtuin 1/PGC-1α pathway.

PubMed

Liu, Guang-Zhong; Hou, Ting-Ting; Yuan, Yue; Hang, Peng-Zhou; Zhao, Jing-Jing; Sun, Li; Zhao, Guan-Qi; Zhao, Jing; Dong, Jing-Mei; Wang, Xiao-Bing; Shi, Hang; Liu, Yong-Wu; Zhou, Jing-Hua; Dong, Zeng-Xiang; Liu, Yang; Zhan, Cheng-Chuang; Li, Yue; Li, Wei-Min

2016-03-01

Atrial metabolic remodelling is critical for the process of atrial fibrillation (AF). The PPAR-α/sirtuin 1 /PPAR co-activator α (PGC-1α) pathway plays an important role in maintaining energy metabolism. However, the effect of the PPAR-α agonist fenofibrate on AF is unclear. Therefore, the aim of this study was to determine the effect of fenofibrate on atrial metabolic remodelling in AF and explore its possible mechanisms of action. The expression of metabolic proteins was examined in the left atria of AF patients. Thirty-two rabbits were divided into sham, AF (pacing with 600 beats·min(-1) for 1 week), fenofibrate treated (pretreated with fenofibrate before pacing) and fenofibrate alone treated (for 2 weeks) groups. HL-1 cells were subjected to rapid pacing in the presence or absence of fenofibrate, the PPAR-α antagonist GW6471 or sirtuin 1-specific inhibitor EX527. Metabolic factors, circulating biochemical metabolites, atrial electrophysiology, adenine nucleotide levels and accumulation of glycogen and lipid droplets were assessed. The PPAR-α/sirtuin 1/PGC-1α pathway was significantly inhibited in AF patients and in the rabbit/HL-1 cell models, resulting in a reduction of key downstream metabolic factors; this effect was significantly restored by fenofibrate. Fenofibrate prevented the alterations in circulating biochemical metabolites, reduced the level of adenine nucleotides and accumulation of glycogen and lipid droplets, reversed the shortened atrial effective refractory period and increased risk of AF. Fenofibrate inhibited atrial metabolic remodelling in AF by regulating the PPAR-α/sirtuin 1/PGC-1α pathway. The present study may provide a novel therapeutic strategy for AF. © 2016 The British Pharmacological Society.

Surface ECG and Fluoroscopy are Not Predictive of Right Ventricular Septal Lead Position Compared to Cardiac CT.

PubMed

Rowe, Matthew K; Moore, Peter; Pratap, Jit; Coucher, John; Gould, Paul A; Kaye, Gerald C

2017-05-01

Controversy exists regarding the optimal lead position for chronic right ventricular (RV) pacing. Placing a lead at the RV septum relies upon fluoroscopy assisted by a surface 12-lead electrocardiogram (ECG). We compared the postimplant lead position determined by ECG-gated multidetector contrast-enhanced computed tomography (MDCT) with the position derived from the surface 12-lead ECG. Eighteen patients with permanent RV leads were prospectively enrolled. Leads were placed in the RV septum (RVS) in 10 and the RV apex (RVA) in eight using fluoroscopy with anteroposterior and left anterior oblique 30° views. All patients underwent MDCT imaging and paced ECG analysis. ECG criteria were: QRS duration; QRS axis; positive or negative net QRS amplitude in leads I, aVL, V1, and V6; presence of notching in the inferior leads; and transition point in precordial leads at or after V4. Of the 10 leads implanted in the RVS, computed tomography (CT) imaging revealed seven to be at the anterior RV wall, two at the anteroseptal junction, and one in the true septum. For the eight RVA leads, four were anterior, two septal, and two anteroseptal. All leads implanted in the RVS met at least one ECG criteria (median 3, range 1-6). However, no criteria were specific for septal position as judged by MDCT. Mean QRS duration was 160 ± 24 ms in the RVS group compared with 168 ± 14 ms for RVA pacing (P = 0.38). We conclude that the surface ECG is not sufficiently accurate to determine RV septal lead tip position compared to cardiac CT. © 2017 Wiley Periodicals, Inc.

Interactive visualization for scar transmurality in cardiac resynchronization therapy

NASA Astrophysics Data System (ADS)

Reiml, Sabrina; Toth, Daniel; Panayiotou, Maria; Fahn, Bernhard; Karim, Rashed; Behar, Jonathan M.; Rinaldi, Christopher A.; Razavi, Reza; Rhode, Kawal S.; Brost, Alexander; Mountney, Peter

2016-03-01

Heart failure is a serious disease affecting about 23 million people worldwide. Cardiac resynchronization therapy is used to treat patients suffering from symptomatic heart failure. However, 30% to 50% of patients have limited clinical benefit. One of the main causes is suboptimal placement of the left ventricular lead. Pacing in areas of myocardial scar correlates with poor clinical outcomes. Therefore precise knowledge of the individual patient's scar characteristics is critical for delivering tailored treatments capable of improving response rates. Current research methods for scar assessment either map information to an alternative non-anatomical coordinate system or they use the image coordinate system but lose critical information about scar extent and scar distribution. This paper proposes two interactive methods for visualizing relevant scar information. A 2-D slice based approach with a scar mask overlaid on a 16 segment heart model and a 3-D layered mesh visualization which allows physicians to scroll through layers of scar from endocardium to epicardium. These complementary methods enable physicians to evaluate scar location and transmurality during planning and guidance. Six physicians evaluated the proposed system by identifying target regions for lead placement. With the proposed method more target regions could be identified.

Resitting a high-stakes postgraduate medical examination on multiple occasions: nonlinear multilevel modelling of performance in the MRCP(UK) examinations.

PubMed

McManus, I C; Ludka, Katarzyna

2012-06-14

Failure rates in postgraduate examinations are often high and many candidates therefore retake examinations on several or even many times. Little, however, is known about how candidates perform across those multiple attempts. A key theoretical question to be resolved is whether candidates pass at a resit because they have got better, having acquired more knowledge or skills, or whether they have got lucky, chance helping them to get over the pass mark. In the UK, the issue of resits has become of particular interest since the General Medical Council issued a consultation and is considering limiting the number of attempts candidates may make at examinations. Since 1999 the examination for Membership of the Royal Colleges of Physicians of the United Kingdom (MRCP(UK)) has imposed no limit on the number of attempts candidates can make at its Part 1, Part 2 or PACES (Clinical) examination. The present study examined the performance of candidates on the examinations from 2002/2003 to 2010, during which time the examination structure has been stable. Data were available for 70,856 attempts at Part 1 by 39,335 candidates, 37,654 attempts at Part 2 by 23,637 candidates and 40,303 attempts at PACES by 21,270 candidates, with the maximum number of attempts being 26, 21 and 14, respectively. The results were analyzed using multilevel modelling, fitting negative exponential growth curves to individual candidate performance. The number of candidates taking the assessment falls exponentially at each attempt. Performance improves across attempts, with evidence in the Part 1 examination that candidates are still improving up to the tenth attempt, with a similar improvement up to the fourth attempt in Part 2 and the sixth attempt at PACES. Random effects modelling shows that candidates begin at a starting level, with performance increasing by a smaller amount at each attempt, with evidence of a maximum, asymptotic level for candidates, and candidates showing variation in starting level, rate of improvement and maximum level. Modelling longitudinal performance across the three diets (sittings) shows that the starting level at Part 1 predicts starting level at both Part 2 and PACES, and the rate of improvement at Part 1 also predicts the starting level at Part 2 and PACES. Candidates continue to show evidence of true improvement in performance up to at least the tenth attempt at MRCP(UK) Part 1, although there are individual differences in the starting level, the rate of improvement and the maximum level that can be achieved. Such findings provide little support for arguments that candidates should only be allowed a fixed number of attempts at an examination. However, unlimited numbers of attempts are also difficult to justify because of the inevitable and ever increasing role that luck must play with increasing numbers of resits, so that the issue of multiple attempts might be better addressed by tackling the difficult question of how a pass mark should increase with each attempt at an exam.

42 CFR 460.34 - Duration of PACE program agreement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.34 Duration of PACE program agreement. An agreement is...

42 CFR 460.34 - Duration of PACE program agreement.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.34 Duration of PACE program agreement. An agreement is...

Early change in thermal perception is not a driver of anticipatory exercise pacing in the heat.

PubMed

Barwood, Martin James; Corbett, Jo; White, Danny; James, Jason

2012-10-01

Initial power output declines significantly during exercise in hot conditions on attaining a rapid increase in skin temperature when exercise commences. It is unclear whether this initial reduced power is mediated consciously, through thermal perceptual cues, or is a subconscious process. The authors tested the hypothesis that improved thermal perception (feeling cooler and more comfortable) in the absence of a change in thermal state (ie, similar deep-body and skin temperatures between spray conditions) would alter pacing and 40 km cycling time trial (TT) performance. Eleven trained participants (mean (SD): age 30 (8.1) years; height 1.78 (0.06) m; mass 76.0 (8.3) kg) completed three 40 km cycling TTs in standardised conditions (32°C, 50% RH) with thermal perception altered prior to exercise by application of cold-receptor-activating menthol spray (MENTHOL SPRAY), in contrast to a separate control spray (CONTROL SPRAY) and no spray control (CON). Thermal perception, perceived exertion, thermal responses and cycling TT performance were measured. MENTHOL SPRAY induced feelings of coolness and improved thermal comfort before and during exercise. Skin temperature profile at the start of exercise was similar between sprays (CON-SPRAY 33.3 (1.1)°C and MENTHOL SPRAY 33.4 (0.4)°C, but different to CON 34.5 (0.5)°C), but there was no difference in the pacing strategy adopted. There was no performance benefit using MENTHOL SPRAY; cycling TT completion time for CON is 71.58 (6.21) min, for CON-SPRAY is 70.94 (6.06) min and for MENTHOL SPRAY is 71.04 (5.47) min. The hypothesis is rejected. Thermal perception is not a primary driver of early pacing during 40 km cycling TT in hot conditions in trained participants.

Effects of a 4-week high-intensity interval training on pacing during 5-km running trial

PubMed Central

Silva, R.; Damasceno, M.; Cruz, R.; Silva-Cavalcante, M.D.; Lima-Silva, A.E.; Bishop, D.J.; Bertuzzi, R.

2017-01-01

This study analyzed the influence of a 4-week high-intensity interval training on the pacing strategy adopted by runners during a 5-km running trial. Sixteen male recreational long-distance runners were randomly assigned to a control group (CON, n=8) or a high-intensity interval training group (HIIT, n=8). The HIIT group performed high-intensity interval-training twice per week, while the CON group maintained their regular training program. Before and after the training period, the runners performed an incremental exercise test to exhaustion to measure the onset of blood lactate accumulation, maximal oxygen uptake (VO2max), and peak treadmill speed (PTS). A submaximal constant-speed test to measure the running economy (RE) and a 5-km running trial on an outdoor track to establish pacing strategy and performance were also done. During the 5-km running trial, the rating of perceived exertion (RPE) and time to cover the 5-km trial (T5) were registered. After the training period, there were significant improvements in the HIIT group of ∼7 and 5% for RE (P=0.012) and PTS (P=0.019), respectively. There was no significant difference between the groups for VO2max (P=0.495) or onset of blood lactate accumulation (P=0.101). No difference was found in the parameters measured during the 5-km trial before the training period between HIIT and CON (P>0.05). These findings suggest that 4 weeks of HIIT can improve some traditional physiological variables related to endurance performance (RE and PTS), but it does not alter the perception of effort, pacing strategy, or overall performance during a 5-km running trial. PMID:29069224

Effects of a 4-week high-intensity interval training on pacing during 5-km running trial.

PubMed

Silva, R; Damasceno, M; Cruz, R; Silva-Cavalcante, M D; Lima-Silva, A E; Bishop, D J; Bertuzzi, R

2017-10-19

This study analyzed the influence of a 4-week high-intensity interval training on the pacing strategy adopted by runners during a 5-km running trial. Sixteen male recreational long-distance runners were randomly assigned to a control group (CON, n=8) or a high-intensity interval training group (HIIT, n=8). The HIIT group performed high-intensity interval-training twice per week, while the CON group maintained their regular training program. Before and after the training period, the runners performed an incremental exercise test to exhaustion to measure the onset of blood lactate accumulation, maximal oxygen uptake (VO2max), and peak treadmill speed (PTS). A submaximal constant-speed test to measure the running economy (RE) and a 5-km running trial on an outdoor track to establish pacing strategy and performance were also done. During the 5-km running trial, the rating of perceived exertion (RPE) and time to cover the 5-km trial (T5) were registered. After the training period, there were significant improvements in the HIIT group of ∼7 and 5% for RE (P=0.012) and PTS (P=0.019), respectively. There was no significant difference between the groups for VO2max (P=0.495) or onset of blood lactate accumulation (P=0.101). No difference was found in the parameters measured during the 5-km trial before the training period between HIIT and CON (P>0.05). These findings suggest that 4 weeks of HIIT can improve some traditional physiological variables related to endurance performance (RE and PTS), but it does not alter the perception of effort, pacing strategy, or overall performance during a 5-km running trial.

Prevalence of E/A wave fusion and A wave truncation in DDD pacemaker patients with complete AV block under nominal AV intervals.

PubMed

Poller, Wolfram C; Dreger, Henryk; Schwerg, Marius; Melzer, Christoph

2015-01-01

Optimization of the AV-interval (AVI) in DDD pacemakers improves cardiac hemodynamics and reduces pacemaker syndromes. Manual optimization is typically not performed in clinical routine. In the present study we analyze the prevalence of E/A wave fusion and A wave truncation under resting conditions in 160 patients with complete AV block (AVB) under the pre-programmed AVI. We manually optimized sub-optimal AVI. We analyzed 160 pacemaker patients with complete AVB, both in sinus rhythm (AV-sense; n = 129) and under atrial pacing (AV-pace; n = 31). Using Doppler analyses of the transmitral inflow we classified the nominal AVI as: a) normal, b) too long (E/A wave fusion) or c) too short (A wave truncation). In patients with a sub-optimal AVI, we performed manual optimization according to the recommendations of the American Society of Echocardiography. All AVB patients with atrial pacing exhibited a normal transmitral inflow under the nominal AV-pace intervals (100%). In contrast, 25 AVB patients in sinus rhythm showed E/A wave fusion under the pre-programmed AV-sense intervals (19.4%; 95% confidence interval (CI): 12.6-26.2%). A wave truncations were not observed in any patient. All patients with a complete E/A wave fusion achieved a normal transmitral inflow after AV-sense interval reduction (mean optimized AVI: 79.4 ± 13.6 ms). Given the rate of 19.4% (CI 12.6-26.2%) of patients with a too long nominal AV-sense interval, automatic algorithms may prove useful in improving cardiac hemodynamics, especially in the subgroup of atrially triggered pacemaker patients with AV node diseases.

ERP evidence for the recognition of emotional prosody through simulated cochlear implant strategies.

PubMed

Agrawal, Deepashri; Timm, Lydia; Viola, Filipa Campos; Debener, Stefan; Büchner, Andreas; Dengler, Reinhard; Wittfoth, Matthias

2012-09-20

Emotionally salient information in spoken language can be provided by variations in speech melody (prosody) or by emotional semantics. Emotional prosody is essential to convey feelings through speech. In sensori-neural hearing loss, impaired speech perception can be improved by cochlear implants (CIs). Aim of this study was to investigate the performance of normal-hearing (NH) participants on the perception of emotional prosody with vocoded stimuli. Semantically neutral sentences with emotional (happy, angry and neutral) prosody were used. Sentences were manipulated to simulate two CI speech-coding strategies: the Advance Combination Encoder (ACE) and the newly developed Psychoacoustic Advanced Combination Encoder (PACE). Twenty NH adults were asked to recognize emotional prosody from ACE and PACE simulations. Performance was assessed using behavioral tests and event-related potentials (ERPs). Behavioral data revealed superior performance with original stimuli compared to the simulations. For simulations, better recognition for happy and angry prosody was observed compared to the neutral. Irrespective of simulated or unsimulated stimulus type, a significantly larger P200 event-related potential was observed for happy prosody after sentence onset than the other two emotions. Further, the amplitude of P200 was significantly more positive for PACE strategy use compared to the ACE strategy. Results suggested P200 peak as an indicator of active differentiation and recognition of emotional prosody. Larger P200 peak amplitude for happy prosody indicated importance of fundamental frequency (F0) cues in prosody processing. Advantage of PACE over ACE highlighted a privileged role of the psychoacoustic masking model in improving prosody perception. Taken together, the study emphasizes on the importance of vocoded simulation to better understand the prosodic cues which CI users may be utilizing.

42 CFR 460.32 - Content and terms of PACE program agreement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.32 Content and terms of PACE program agreement. (a...

42 CFR 460.90 - PACE benefits under Medicare and Medicaid.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Services § 460.90 PACE benefits under Medicare and Medicaid. If a Medicare...

Multi-Leu PACE4 Inhibitor Retention within Cells Is PACE4 Dependent and a Prerequisite for Antiproliferative Activity

PubMed Central

Ly, Kévin; Levesque, Christine; Kwiatkowska, Anna; Ait-Mohand, Samia; Desjardins, Roxane; Guérin, Brigitte; Day, Robert

2015-01-01

The overexpression as well as the critical implication of the proprotein convertase PACE4 in prostate cancer progression has been previously reported and supported the development of peptide inhibitors. The multi-Leu peptide, a PACE4-specific inhibitor, was further generated and its capability to be uptaken by tumor xenograft was demonstrated with regard to its PACE4 expression status. To investigate whether the uptake of this inhibitor was directly dependent of PACE4 levels, uptake and efflux from cancer cells were evaluated and correlations were established with PACE4 contents on both wild type and PACE4-knockdown cell lines. PACE4-knockdown associated growth deficiencies were established on the knockdown HepG2, Huh7, and HT1080 cells as well as the antiproliferative effects of the multi-Leu peptide supporting the growth capabilities of PACE4 in cancer cells. PMID:26114115

Helping Family Physicians Improve Their Cardiac Auscultation Skills with an Interactive CD-ROM.

ERIC Educational Resources Information Center

Roy, Douglas; Sargeant, Joan; Gray, Jean; Hoyt, Brian; Allen, Michael; Fleming, Michael

2002-01-01

Physicians (n=42) studied cardiac auscultation using a 15-hour CD-ROM program. Nine months later, 21 who completed a posttest showed significant improvement in identifying heart sounds. CDs were valued for opportunities to review material at an individual pace. Lack of computer skills hindered use. (Contains 26 references.) (SK)

Educational Salvation: Integrating Critical Spirituality in Educational Leadership

ERIC Educational Resources Information Center

McCray, Carlos R.; Beachum, Floyd D.; Yawn, Christopher

2012-01-01

Improving education for students in K-12 urban settings remains a slow-paced and difficult task, with many successes in student learning being episodic at best. The disconnect between government mandates to improve schools and persistent societal issues of poverty and inequity act to increase stress on teachers and educational leaders working in…

Prevention of Atrial Fibrillation by Using Sarcoplasmic Reticulum Calcium ATPase Pump Overexpression in a Rabbit Model of Rapid Atrial Pacing.

PubMed

Wang, Hong Li; Zhou, Xian Hui; Li, Zhi Qiang; Fan, Ping; Zhou, Qi Na; Li, Yao Dong; Hou, Yue Mei; Tang, Bao Peng

2017-08-16

BACKGROUND Recent research suggests that abnormal Ca2+ handling plays a role in the occurrence and maintenance of atrial fibrillation (AF). Therefore, Ca2+ release and ingestion depend on properties of the ryanodine receptor (RyR) and sarcoplasmic reticulum Ca2+ATPase2a (SERCA2a). This study aimed to detect whether SERCA2a gene overexpression has a preventive effect on atrial fibrillation caused by rapid pacing right atrium. MATERIAL AND METHODS Forty-eight New Zealand white rabbits were randomly divided into a control group, AF group, AAV9/GFP group, and AAV9/SERCA2a group. The right atrium was rapidly paced at 600 beats/min for 30 days after an intraperitoneal injection of an adeno-associated virus expressing the SERCA2a gene and GFP. The AF induction rate and the effective refraction period (ERP) were measured after 0, 4, 8, 12, and 24 h of pacing. Western blot analysis was used to test for the expression of SERCA2a. Changes in atrial tissue structure were observed by H&E staining and electron microscopy. RESULTS The AF induction rate was higher in the AF groups than in the AAV9/SERCA2a group at different time points of pacing. After 12 h of pacing, ERP was significantly prolonged in the AAV9/SERCA2a group compared to the AF and AAV9/GFP groups (p<0.05). SERCA2a protein expression was significantly lower in the AF and AAV9/GFP groups compared to the control group (p<0.05), while expression was significantly higher in the AAV9/SERCA2a group than in the AF and AAV9/GFP groups (p<0.05). The myocardial structure of the AAV9/SERCA2a group was significantly improved compared with the AF group, indicating that SERCA2a overexpression relieved the structural remodeling of atrial fibrillation. CONCLUSIONS SERCA2a overexpression is capable of suppressing ERP shortening and AF induced by rapid pacing atrium. SERCA2a gene therapy is expected to be a new anti-atrial fibrillation strategy.

Left ventricular approach for recording His bundle potential in man.

PubMed

Lee, Y S; Lien, W P

1975-06-01

The electrical potentials of the His bundle (HB) were recorded from the left ventricular endocardial surface in 28 patients ranging from 16 to 63 years of age. In 14 of the patients the left bundle branch (LB) potentials were also obtained. Placement of a bipolar electrode catheter tip toward the interventricular septum, right at and also 1 to 2 cm below the aortic valve, resulted in stable recordings of both potentials in successive cardiac cycles even at performing atrial or HB pacing from the right heart. The following intervals were measured in milliseconds (msec): P-A, A-H, H, H-V, LB, and LB-V. The average values in 12 patients (average age 26 plus or minus 7 years and average heart rate 90 plus or minus 16 beats per minute) with normal A-V conduction were as follows: P-A 28 plus or minus 7, A-H 76 plus or minus 16, H 19 plus or minus 3 and H-V 45 plus or minus 6 msec. The average values for LB and LB-V in 10 of these 12 patients were 15 plus or minus 3 and 25 plus or minus 3 msec respectively. Validation of the His bundle electrogram (HBE) from the left ventricular endocardial surface was based on simultaneous recordings of the intracardiac electrograms from both left and right sides of the heart in 18 patients. The individual average values for the intervals obtained from both sides of the heart in these patients were statistically not different, except that the H potential was slightly longer in duration fr m the left heart (P equals 0.05). Among these, 16 showed simultaneous onset of the H potentials, and the LB-V and RB-V conduction times from comparable points were almost the same. Indications for the left sided electro-physiologic studies include the following situations: (a) inability to record H from the right of the heart; (b) giant right atrium; and (c) possibly during atrial fibrillation.

Intensive Language Action Therapy in Chronic Aphasia: A Randomized Clinical Trial Examining Guidance by Constraint

PubMed Central

Stanek,, Edward J.; Stokes, Polly; Li, Minming; Andrianopoulos, Mary

2016-01-01

Purpose Intensive language action therapy (ILAT) can be effective in overcoming learned nonuse in chronic aphasia. It is suggested that all three guiding principles (constraint, communication embedding, massed practice) are essential to ILAT's success. We examined whether one of these, guidance by constraint, is critical. Method Twenty-four participants with aphasia (PWAs) were assigned to ILAT or a modified version of promoting aphasic communicative effectiveness (PACE) in a randomized block, single-blind, parallel-group treatment study. Blocking was by severity (mild/moderate, moderate to severe, severe). Both groups received intensive treatment in the context of therapeutic language action games. Whereas the ILAT group was guided toward spoken responses, the PACE group could choose any response modality. Results All participants, whether assigned to ILAT or PACE groups, improved on the primary outcome measure, picture naming. There was a Severity × Treatment interaction, with the largest effects estimated for PWAs with mild/moderate and moderate to severe aphasia. Regardless of severity, the ILAT group outperformed the PACE group on untrained pictures, suggesting some benefit of ILAT to generalization. However, this difference was not statistically significant. Conclusion Although the groups differed in subtle ways, including better generalization to untrained pictures for ILAT, the study was inconclusive on the influence of guidance by constraint. PMID:27997954

Localized grey matter damage in early primary progressive multiple sclerosis contributes to disability.

PubMed

Khaleeli, Z; Cercignani, M; Audoin, B; Ciccarelli, O; Miller, D H; Thompson, A J

2007-08-01

Disability in primary progressive multiple sclerosis (PPMS) has been correlated with damage to the normal appearing brain tissues. Magnetization transfer ratio (MTR) and volume changes indicate that much of this damage occurs in the normal appearing grey matter, but the clinical significance of this remains uncertain. We aimed to localize these changes to distinct grey matter regions, and investigate the clinical impact of the MTR changes. 46 patients with early PPMS and 23 controls underwent MT and high-resolution T1-weighted imaging. Patients were scored on the Expanded Disability Status Scale (EDSS), Multiple Sclerosis Functional Composite and subtests (Nine-Hole Peg Test, Timed Walk Test, Paced Auditory Serial Addition Test [PASAT]). Grey matter volume and MTR were compared between patients and controls, adjusting for age. Mean MTR for significant regions within the motor network and in areas relevant to PASAT performance were correlated with appropriate clinical scores, adjusting for grey matter volume. Patients showed reduced MTR and atrophy in the right pre- and left post-central gyri, right middle frontal gyrus, left insula, and thalamus bilaterally. Reduced MTR without significant atrophy occurred in the left pre-central gyrus, left superior frontal gyri, bilateral superior temporal gyri, right insula and visual cortex. Higher EDSS correlated with lower MTR in the right primary motor cortex (BA 4). In conclusion, localized grey matter damage occurs in early PPMS, and MTR change is more widespread than atrophy. Damage demonstrated by reduced MTR is clinically eloquent.

Freeway bottleneck removals : workshop enhancement and technology transfer.

DOT National Transportation Integrated Search

2009-12-01

As transportation improvement projects become increasingly costly and complex and as funding sources are not : keeping pace with needs in highly urbanized areas, it becomes critical that existing freeway systems be finetuned to : maximize capacity...

Pace-capture-guided ablation after contact-force-guided pulmonary vein isolation: results of the randomized controlled DRAGON trial.

PubMed

Masuda, Masaharu; Fujita, Masashi; Iida, Osamu; Okamoto, Shin; Ishihara, Takayuki; Nanto, Kiyonori; Kanda, Takashi; Sunaga, Akihiro; Tsujimura, Takuya; Matsuda, Yasuhiro; Ohashi, Takuya; Uematsu, Masaaki

2017-11-17

Before the discovery of contact-force guidance, eliminating pacing capture along the pulmonary vein (PV) isolation line had been reported to improve PV isolation durability and rhythm outcomes. DRAGON (UMIN-CTR, UMIN000015332) aimed to elucidate the efficacy of pace-capture-guided ablation following contact-force-guided PV isolation ablation in paroxysmal atrial fibrillation (AF) patients. A total of 156 paroxysmal AF patients with AF-trigger ectopies from any of the four PVs induced by isoproterenol were randomly assigned to undergo pace-capture-guided ablation along a contact-force-guided isolation line around AF-trigger PVs (PC group, n = 76) or contact-force-guided PV isolation ablation alone (control group, n = 80). Follow-up of at least 1 year commenced with serial 24 h Holter and symptom-triggered ambulatory monitoring. There was no significant difference in acute PV reconnection rates during a 20 min waiting period after the last ablation or adenosine infusion testing between the PC and the control groups (per patient, 21% vs. 27%, P = 0.27; per AF-trigger PV, 5.9% vs. 7.3%, P = 0.70; and per non-AF-trigger PV, 7.1% vs. 7.4%, P = 0.92). Atrial tachyarrhythmia-free survival rates off antiarrhythmic drugs after the initial session were comparable at 19.3 ± 6.2 months between the two groups (82% vs. 80%, P = 0.80). Among 22 patients who required a second ablation procedure, there was no difference between the PC and the control groups in the PV reconnection rates at both previously AF-trigger (29% vs. 43%, P = 0.70) and non-AF-trigger PVs (18% vs. 19%, P = 0.88). Pace-capture-guided ablation performed after contact-force-guided PV isolation demonstrated no improvement in PV isolation durability or rhythm outcome. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Ice slurry ingestion does not enhance self-paced intermittent exercise in the heat.

PubMed

Gerrett, N; Jackson, S; Yates, J; Thomas, G

2017-11-01

This study aimed to determine if ice slurry ingestion improved self-paced intermittent exercise in the heat. After a familiarisation session, 12 moderately trained males (30.4 ± 3.4 year, 1.8 ± 0.1 cm, 73.5 ± 14.3 kg, V˙O 2max 58.5 ± 8.1 mL/kg/min) completed two separate 31 min self-paced intermittent protocols on a non-motorised treadmill in 30.9 ± 0.9 °C, 41.1 ± 4.0% RH. Thirty minutes prior to exercise, participants consumed either 7.5 g/kg ice slurry (0.1 ± 0.1 °C) (ICE) or 7.5 g/kg water (23.4 ± 0.9 °C) (CONTROL). Despite reductions in T c (ΔT c : -0.51 ± 0.3 °C, P < 0.05) and thermal sensation prior to exercise, ICE did not enhance self-paced intermittent exercise compared to CONTROL. The average speed during the walk (CONTROL: 5.90 ± 1.0 km, ICE: 5.90 ± 1.0 km), jog (CONTROL: 8.89 ± 1.7 km, ICE: 9.11 ± 1.5 km), run (CONTROL: 12.15 ± 1.7 km, ICE: 12.54 ± 1.5 km) and sprint (CONTROL: 17.32 ± 1.3 km, ICE: 17.18 ± 1.4 km) was similar between conditions (P > 0.05). Mean T sk , T b , blood lactate, heart rate and RPE were similar between conditions (P > 0.05). The findings suggest that lowering T c prior to self-paced intermittent exercise does not translate into an improved performance. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Right ventricular pacemaker lead position is associated with differences in long-term outcomes and complications.

PubMed

Witt, Chance M; Lenz, Charles J; Shih, Henry H; Ebrille, Elisa; Rosenbaum, Andrew N; van Zyl, Martin; Aung, Htin; Manocha, Kevin K; Deshmukh, Abhishek J; Hodge, David O; Mulpuru, Siva K; Cha, Yong-Mei; Espinosa, Raul E; Asirvatham, Samuel J; Mcleod, Christopher J

2017-08-01

Cardiac pacing from the right ventricular apex is associated with detrimental long-term effects and nonapical pacing locations may be associated with improved outcomes. There is little data regarding complications with nonapical lead positions. The aim of this study was to assess long-term outcomes and lead-related complications associated with differing ventricular lead tip position. All adult patients who underwent dual-chamber pacemaker implantation from 2004 to 2014 were included if they had postprocedure chest radiographs amenable to lead position determination. Long-term outcomes and lead-related complication rates were recorded. These were compared at 5 years between: (1) apical and septal leads, (2) apical and nonseptal nonapical (NSNA), and (3) apical and septal with >40% ventricular pacing. We retrospectively evaluated 3,450 patients, which included 238 with a septal position and 733 with NSNA lead positions. Septal lead position was associated with a lower mortality compared to apical leads (24% vs. 31%, P = 0.02). In patients with greater than 40% pacing, septal leads were associated with significantly higher rates of incident atrial fibrillation compared to apical leads (49% vs. 34%, P = 0.04). NSNA positions were associated with a significantly higher rate of lead dislodgement (4% vs. 2%, P = 0.005) and need for revision (8% vs. 5%, P = 0.005). Septal pacemaker lead position is associated with a lower mortality compared to apically placed leads, but a higher incidence of atrial fibrillation with higher percentage ventricular pacing. NSNA lead locations are associated with more complications and should be avoided. © 2017 Wiley Periodicals, Inc.

Memory effects, transient growth, and wave breakup in a model of paced atrium

NASA Astrophysics Data System (ADS)

Garzón, Alejandro; Grigoriev, Roman O.

2017-09-01

The mechanisms underlying cardiac fibrillation have been investigated for over a century, but we are still finding surprising results that change our view of this phenomenon. The present study focuses on the transition from normal rhythm to spiral wave chaos associated with a gradual increase in the pacing rate. While some of our findings are consistent with existing experimental, numerical, and theoretical studies of this problem, one result appears to contradict the accepted picture. Specifically we show that, in a two-dimensional model of paced homogeneous atrial tissue, transition from discordant alternans to conduction block, wave breakup, reentry, and spiral wave chaos is associated with the transient growth of finite amplitude disturbances rather than a conventional instability. It is mathematically very similar to subcritical, or bypass, transition from laminar fluid flow to turbulence, which allows many of the tools developed in the context of fluid turbulence to be used for improving our understanding of cardiac arrhythmias.

Automatic user customization for improving the performance of a self-paced brain interface system.

PubMed

Fatourechi, Mehrdad; Bashashati, Ali; Birch, Gary E; Ward, Rabab K

2006-12-01

Customizing the parameter values of brain interface (BI) systems by a human expert has the advantage of being fast and computationally efficient. However, as the number of users and EEG channels grows, this process becomes increasingly time consuming and exhausting. Manual customization also introduces inaccuracies in the estimation of the parameter values. In this paper, the performance of a self-paced BI system whose design parameter values were automatically user customized using a genetic algorithm (GA) is studied. The GA automatically estimates the shapes of movement-related potentials (MRPs), whose features are then extracted to drive the BI. Offline analysis of the data of eight subjects revealed that automatic user customization improved the true positive (TP) rate of the system by an average of 6.68% over that whose customization was carried out by a human expert, i.e., by visually inspecting the MRP templates. On average, the best improvement in the TP rate (an average of 9.82%) was achieved for four individuals with spinal cord injury. In this case, the visual estimation of the parameter values of the MRP templates was very difficult because of the highly noisy nature of the EEG signals. For four able-bodied subjects, for which the MRP templates were less noisy, the automatic user customization led to an average improvement of 3.58% in the TP rate. The results also show that the inter-subject variability of the TP rate is also reduced compared to the case when user customization is carried out by a human expert. These findings provide some primary evidence that automatic user customization leads to beneficial results in the design of a self-paced BI for individuals with spinal cord injury.

“Just one animal among many?” Existential phenomenology, ethics, and stem cell research

PubMed Central

2010-01-01

Stem cell research and associated or derivative biotechnologies are proceeding at a pace that has left bioethics behind as a discipline that is more or less reactionary to their developments. Further, much of the available ethical deliberation remains determined by the conceptual framework of late modern metaphysics and the correlative ethical theories of utilitarianism and deontology. Lacking, to any meaningful extent, is a sustained engagement with ontological and epistemological critiques, such as with “postmodern” thinking like that of Heidegger’s existential phenomenology. Some basic “Heideggerian” conceptual strategies are reviewed here as a way of remedying this deficiency and adding to ethical deliberation about current stem cell research practices. PMID:20521117

Diaphragm Pacing.

PubMed

DiMarco, Anthony F

2018-06-01

Diaphragm pacing (DP) is a useful and cost-effective alternative to mechanical ventilation in patients with ventilator-dependent spinal cord injury and central hypoventilation syndrome. Patients with SCI should be carefully screened to assess the integrity of their phrenic nerves. In eligible patients, DP improves mobility, speech, olfaction, and quality of life. The stigma of being attached to a mechanical device and risk of ventilator disconnection are eliminated. There is also some evidence that DP results in a reduction in the rate of respiratory tract infections. DP is associated with infrequent side effects and complications, such as wire breakage, radiofrequency failure, and infection. Copyright © 2018 Elsevier Inc. All rights reserved.

Indications for permanent pacing and pacing mode prescription from 1989 to 2006. Experience of a single academic centre in Northern Greece.

PubMed

Styliadis, Ioannis H; Mantziari, Aggeliki P; Gouzoumas, Nikolaos I; Vassilikos, Vasilios P; Paraskevaidis, Stelios A; Mochlas, Sotirios T; Boufidou, Amalia I; Parcharidis, Georgios E

2008-01-01

Indications for pacing and pacing mode prescription have changed in the past decades following advances in pacemaker technology. The aim of the present study was to evaluate changes in indications for pacing and pacing modes during the years 1989-2006 in a single academic pacemaker centre in Northern Greece. Archives of permanent pacemaker implantation procedures were studied retrospectively and data from all implants, first or replacements, were retrieved. Data from 2078 procedures were found, 78.7% of which were first implantations. Patients were 54% male with mean age 72.5 years. Main indications for pacing were atrioventricular block (AVB, 45.7%), sick sinus syndrome (SSS, 32.8%), and atrial fibrillation (12.1%). Almost half (48.9%) of the AVB cases were complete AVB, while the most common types of SSS were tachy-brady syndrome (44.1%) and asystole (27.1%). Rare indications for pacing were carotid sinus syndrome (5.0%), heart failure (3.3%) and hypertrophic obstructive cardiomyopathy (1.0%). The two most frequently used pacing modes were VVI (38.5%) and DDD (25.8%). However, pacing modes have changed greatly over the years, with a marked increase in dual-chamber pacing after 1997 and a preference for rate responsive units after 2002. Biventricular systems were also used in selected patients with heart failure from 2002 on. Indications for pacing and pacing mode prescription in our centre are similar to other pacemaker registries and reflect the global trend in pacing for mimicking the physiological activity of the heart and for addressing problems other than symptomatic bradycardia.

Attention in Hyperactive Children and the Effect of Methylphenidate (Ritalin)

ERIC Educational Resources Information Center

Sykes, Donald H.; And Others

1971-01-01

Hyperactive children treated with methylphenidate (ritalin) showed a significant improvement in all aspects of performance in an experimenter-paced task when compared to a control group of hyperactive children given a placebo. (Author/WY)

Maintained Physical Activity Induced Changes in Delay Discounting.

PubMed

Sofis, Michael J; Carrillo, Ale; Jarmolowicz, David P

2017-07-01

Those who discount the subjective value of delayed rewards less steeply are more likely to engage in physical activity. There is limited research, however, showing whether physical activity can change rates of delay discounting. In a two-experiment series, treatment and maintenance effects of a novel, effort-paced physical activity intervention on delay discounting were evaluated with multiple baseline designs. Using a lap-based method, participants were instructed to exercise at individualized high and low effort levels and to track their own perceived effort. The results suggest that treatment-induced changes in discounting were maintained at follow-up for 13 of 16 participants. In Experiment 2, there were statistically significant group-level improvements in physical activity and delay discounting when comparing baseline with both treatment and maintenance phases. Percentage change in delay discounting was significantly correlated with session attendance and relative pace (min/mile) improvement over the course of the 7-week treatment. Implications for future research are discussed.

Relative refractoriness of left ventricular contraction underlies human tachycardia-induced mechanical and electrical alternans.

PubMed

Kashimura, Takeshi; Kodama, Makoto; Watanabe, Tohru; Tanaka, Komei; Hayashi, Yuka; Ohno, Yukako; Obata, Hiroaki; Ito, Masahiro; Hirono, Satoru; Hanawa, Haruo; Minamino, Tohru

2014-02-01

Mechanical alternans (MA) and electrical alternans (EA) are predictors of cardiac events. Experimental studies have suggested that refractoriness of calcium cycling underlies these cardiac alternans. However, refractoriness of left ventricular contraction has not been examined in patients with cardiac alternans. In 51 patients with miscellaneous heart diseases, incremental right atrial pacing was performed to induce MA and EA. MA was quantified by alternans amplitude (AA: the difference between left ventricular dP/dt of a strong beat and that of a weak beat), and AA at 100/min (AA100) and maximal AA (AAmax) were measured. EA was defined as alternation of T wave morphology in 12-lead electrocardiogram. Relative refractoriness of left ventricular contraction was examined by drawing the mechanical restitution curve under a basal coupling interval (BCL) of 600 ms (100/min) and was assessed by the slope at BCL (Δmechanical restitution). Postextrasystolic potentiation (PESP) was also examined and the slope of PESP curve (ΔPESP) was assessed as a property to alternate strong and weak beats. MA and EA were induced in 19 patients and in none at 100/min or less, and at any heart rate in 32 and in 10, respectively. AA100 and AAmax correlated positively with Δmechanical restitution and negatively with ΔPESP. Patients with EA had a significantly larger Δmechanical restitution and a significantly larger absolute value of ΔPESP than those without. In patients with MA and EA, the left ventricular contractile force during tachycardia is under relative refractoriness and prone to cause large fluctuation of contractile force. ©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.

Acute effects of unilateral temporary stellate ganglion block on human atrial electrophysiological properties and atrial fibrillation inducibility.

PubMed

Leftheriotis, Dionyssios; Flevari, Panayota; Kossyvakis, Charalampos; Katsaras, Dimitrios; Batistaki, Chrysanthi; Arvaniti, Chrysa; Giannopoulos, Georgios; Deftereos, Spyridon; Kostopanagiotou, Georgia; Lekakis, John

2016-11-01

In experimental models, stellate ganglion block (SGB) reduces the induction of atrial fibrillation (AF), while data in humans are limited. The aim of this study was to assess the effect of unilateral SGB on atrial electrophysiological properties and AF induction in patients with paroxysmal AF. Thirty-six patients with paroxysmal AF were randomized in a 2:1 order to temporary, transcutaneous, pharmaceutical SGB with lidocaine or placebo before pulmonary vein isolation. Lidocaine was 1:1 randomly infused to the right or left ganglion. Before and after randomization, atrial effective refractory period (ERP) of each atrium, difference between right and left atrial ERP, intra- and interatrial conduction time, AF inducibility, and AF duration were assessed. After SGB, right atrial ERP was prolonged from a median (1st-3rd quartile) of 240 (220-268) ms to 260 (240-300) ms (P < .01) and left atrial ERP from 235 (220-260) ms to 245 (240-280) ms (P < .01). AF was induced by atrial pacing in all 24 patients before SGB, but only in 13 patients (54%) after the intervention (P < .01). AF duration was shorter after SGB: 1.5 (0.0-5.8) minutes from 5.5 (3.0-12.0) minutes (P < .01). Intra- and interatrial conduction time was not significantly prolonged. No significant differences were observed between right and left SGB. No changes were observed in the placebo group. Unilateral temporary SGB prolonged atrial ERP, reduced AF inducibility, and decreased AF duration. An equivalent effect of right and left SGB on both atria was observed. These findings may have a clinical implication in the prevention of drug refractory and postsurgery AF and deserve further clinical investigation. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

A Comprehensive Analysis of High School Genetics Standards: Are States Keeping Pace with Modern Genetics?

PubMed Central

Dougherty, M.J.; Pleasants, C.; Solow, L.; Wong, A.; Zhang, H.

2011-01-01

Science education in the United States will increasingly be driven by testing and accountability requirements, such as those mandated by the No Child Left Behind Act, which rely heavily on learning outcomes, or “standards,” that are currently developed on a state-by-state basis. Those standards, in turn, drive curriculum and instruction. Given the importance of standards to teaching and learning, we investigated the quality of life sciences/biology standards with respect to genetics for all 50 states and the District of Columbia, using core concepts developed by the American Society of Human Genetics as normative benchmarks. Our results indicate that the states’ genetics standards, in general, are poor, with more than 85% of the states receiving overall scores of Inadequate. In particular, the standards in virtually every state have failed to keep pace with changes in the discipline as it has become genomic in scope, omitting concepts related to genetic complexity, the importance of environment to phenotypic variation, differential gene expression, and the differences between inherited and somatic genetic disease. Clearer, more comprehensive genetics standards are likely to benefit genetics instruction and learning, help prepare future genetics researchers, and contribute to the genetic literacy of the U.S. citizenry. PMID:21885828

Prospective randomized study to assess the efficacy of site and rate of atrial pacing on long-term progression of atrial fibrillation in sick sinus syndrome: Septal Pacing for Atrial Fibrillation Suppression Evaluation (SAFE) Study.

PubMed

Lau, Chu-Pak; Tachapong, Ngarmukos; Wang, Chun-Chieh; Wang, Jing-Feng; Abe, Haruhiko; Kong, Chi-Woon; Liew, Reginald; Shin, Dong-Gu; Padeletti, Luigi; Kim, You-Ho; Omar, Razali; Jirarojanakorn, Kreingkrai; Kim, Yoon-Nyun; Chen, Mien-Cheng; Sriratanasathavorn, Charn; Munawar, Muhammad; Kam, Ruth; Chen, Jan-Yow; Cho, Yong-Keun; Li, Yi-Gang; Wu, Shu-Lin; Bailleul, Christophe; Tse, Hung-Fat

2013-08-13

Atrial-based pacing is associated with lower risk of atrial fibrillation (AF) in sick sinus syndrome compared with ventricular pacing; nevertheless, the impact of site and rate of atrial pacing on progression of AF remains unclear. We evaluated whether long-term atrial pacing at the right atrial (RA) appendage versus the low RA septum with (ON) or without (OFF) a continuous atrial overdrive pacing algorithm can prevent the development of persistent AF. We randomized 385 patients with paroxysmal AF and sick sinus syndrome in whom a pacemaker was indicated to pacing at RA appendage ON (n=98), RA appendage OFF (n=99), RA septum ON (n=92), or RA septum OFF (n=96). The primary outcome was the occurrence of persistent AF (AF documented at least 7 days apart or need for cardioversion). Demographic data were homogeneous across both pacing site (RA appendage/RA septum) and atrial overdrive pacing (ON/OFF). After a mean follow-up of 3.1 years, persistent AF occurred in 99 patients (25.8%; annual rate of persistent AF, 8.3%). Alternative site pacing at the RA septum versus conventional RA appendage (hazard ratio=1.18; 95% confidence interval, 0.79-1.75; P=0.65) or continuous atrial overdrive pacing ON versus OFF (hazard ratio=1.17; 95% confidence interval, 0.79-1.74; P=0.69) did not prevent the development of persistent AF. In patients with paroxysmal AF and sick sinus syndrome requiring pacemaker implantation, an alternative atrial pacing site at the RA septum or continuous atrial overdrive pacing did not prevent the development of persistent AF. URL: http://www.clinicaltrials.gov. UNIQUE IDENTIFIER: NCT00419640.

Renal sympathetic denervation inhibits the development of left ventricular mechanical dyssynchrony during the progression of heart failure in dogs.

PubMed

Hu, Wei; Zhao, Qing-yan; Yu, Sheng-bo; Sun, Bin; Chen, Liao; Cao, Sheng; Guo, Rui-qiang

2014-11-22

The purpose of this study was to investigate whether transcatheter renal sympathetic denervation (RSD) interfere with the development of left ventricular (LV) mechanical dyssynchrony during the progression of heart failure (HF). Nineteen beagles were randomly divided into sham-operated group (six dogs), control group (seven dogs), and RSD group (six dogs). Sham-operated group were implanted with pacemakers without pacing; Control group were implanted with pacemakers and underwent 3 weeks of rapid right ventricular pacing; and RSD group underwent catheter-based RSD bilaterally and were simultaneously implanted with pacemakers. Both LV strain and LV dyssynchrony were analyzed via 2D speckle-tracking strain echocardiography to evaluate LV function. Longitudinal dyssynchrony was determined as the standard deviation for time-to-peak speckle-tracking strain on apical 4- and 2-chamber views. Radial and circumferential dyssynchrony was determined as the standard deviation for time-to-peak speckle-tracking strain in mid- and base-LV short-axis views. Each myocardial function was also evaluated by averaging the peak systolic strains. LV systolic pressure (LVSP) and LV end-diastolic pressure (LVEDP) were measured. The LV interstitial fibrosis was determined by histological analysis. Plasma angiotensin II (Ang II), aldosterone and norepinephrine (NE) levels were also measured. After 3 weeks, all of the dogs in both the control and RSD groups showed greater LV end-diastolic volume compared with the sham-operated group; however, the dogs in the RSD group had a higher LV ejection fraction (LVEF) than the dogs in the control group (p<0.001). The LV systolic strains were higher in the RSD group than in the control group (p<0.001 for longitudinal, circumferential and radial strain, respectively). The levels of LV dyssynchrony were lower in the RSD group than in the control group (p<0.001 for longitudinal, circumferential and radial dyssynchrony, respectively). Compared with dogs with control alone, RSD dogs had lower LV end-diastolic pressures and less fibrous tissue. The levels of plasma Ang II, aldosterone and NE were lower in the RSD group than in the control group. RSD inhibites the development of left ventricular mechanical dyssynchrony during the progression of heart failure in dogs.

MitraClip in CRT non-responders with severe mitral regurgitation.

PubMed

Seifert, Martin; Schau, Thomas; Schoepp, Maren; Arya, Anita; Neuss, Michael; Butter, Christian

2014-11-15

Severe mitral regurgitation (MR) ≥ 3+ and left ventricular dyssynchrony in heart failure patients are markers of CRT non response. The MitraClip (MC) implantation is a therapy for MR ≥ 3+ in patients with high surgical risk of mitral valve reconstruction. We investigated 42 patients with CRT and MR ≥ 3+ who received an MC device at our center. One and two year mortality rates were compared with the predicted mortality by Seattle Heart Failure Model (SHFM) and meta-analysis global group in chronic heart failure (MAGGIC), using the baseline characteristics of patients at the time of MC implantation. The median time interval between CRT and MC implantation was 20.1 (4.5-43.3) months. In 19 patients we observed a functional regurgitation with normal leaflets and in 23 patients a degenerative mechanism for mitral regurgitation. There was no change in mean QRS duration by biventricular pacing or MC implantation. The use of MC led to significant reductions in: median N-terminal pro-brain natriuretic peptide (NT-proBNP) level (pg/ml) from 3923 to 2636 (p = 0.02), tricuspid regurgitation pressure gradient (TRPG) from 43 to 35 mmHg (p = 0.019) and in left ventricular end-diastolic volume (LVEDV) by MC (p = 0.008). At the 2 year follow-up interval the all-cause mortality was 25%. MC implantation leads to an improvement of NT-proBNP level, TRPG and LVEDV in both functional and degenerative MR but does not influence QRS duration. Two year all-cause mortality was 25% and did not differ significantly from that predicted by SHFM and MAGGIC. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The influence of right ventricular stimulation on acute response to cardiac resynchronisation therapy.

PubMed

Wu, L; de Roest, G J; Hendriks, M L; van Rossum, A C; de Cock, C C; Allaart, C P

2016-01-01

The contribution of right ventricular (RV) stimulation to cardiac resynchronisation therapy (CRT) remains controversial. RV stimulation might be associated with adverse haemodynamic effects, dependent on intrinsic right bundle branch conduction, presence of scar, RV function and other factors which may partly explain non-response to CRT. This study investigates to what degree RV stimulation modulates response to biventricular (BiV) stimulation in CRT candidates and which baseline factors, assessed by cardiac magnetic resonance imaging, determine this modulation. Forty-one patients (24 (59 %) males, 67 ± 10 years, QRS 153 ± 22 ms, 21 (51 %) ischaemic cardiomyopathy, left ventricular (LV) ejection fraction 25 ± 7 %), who successfully underwent temporary stimulation with pacing leads in the RV apex (RVapex) and left ventricular posterolateral (PL) wall were included. Stroke work, assessed by a conductance catheter, was used to assess acute haemodynamic response during baseline conditions and RVapex, PL (LV) and PL+RVapex (BiV) stimulation. Compared with baseline, stroke work improved similarly during LV and BiV stimulation (∆+ 51 ± 42 % and ∆+ 48 ± 47 %, both p < 0.001), but individual response showed substantial differences between LV and BiV stimulation. Multivariate analysis revealed that RV ejection fraction (β = 1.01, p = 0.02) was an independent predictor for stroke work response during LV stimulation, but not for BiV stimulation. Other parameters, including atrioventricular delay and scar presence and localisation, did not predict stroke work response in CRT. The haemodynamic effect of addition of RVapex stimulation to LV stimulation differs widely among patients receiving CRT. Poor RV function is associated with poor response to LV but not BiV stimulation.

42 CFR 460.90 - PACE benefits under Medicare and Medicaid.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false PACE benefits under Medicare and Medicaid. 460.90 Section 460.90 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN... FOR THE ELDERLY (PACE) PACE Services § 460.90 PACE benefits under Medicare and Medicaid. If a Medicare...

Safety of the Wearable Cardioverter Defibrillator (WCD) in Patients with Implanted Pacemakers.

PubMed

Schmitt, Joern; Abaci, Guezine; Johnson, Victoria; Erkapic, Damir; Gemein, Christopher; Chasan, Ritvan; Weipert, Kay; Hamm, Christian W; Klein, Helmut U

2017-03-01

The wearable cardioverter defibrillator (WCD) is an important approach for better risk stratification, applied to patients considered to be at high risk of sudden arrhythmic death. Patients with implanted pacemakers may also become candidates for use of the WCD. However, there is a potential risk that pacemaker signals may mislead the WCD detection algorithm and cause inappropriate WCD shock delivery. The aim of the study was to test the impact of different types of pacing, various right ventricular (RV) lead positions, and pacing modes for potential misleading of the WCD detection algorithm. Sixty patients with implanted pacemakers received the WCD for a short time and each pacing mode (AAI, VVI, and DDD) was tested for at least 30 seconds in unipolar and bipolar pacing configuration. In case of triggering the WCD detection algorithm and starting the sequence of arrhythmia alarms, shock delivery was prevented by pushing of the response buttons. In six of 60 patients (10%), continuous unipolar pacing in DDD mode triggered the WCD detection algorithm. In no patient, triggering occurred with bipolar DDD pacing, unipolar and bipolar AAI, and VVI pacing. Triggering was independent of pacing amplitude, RV pacing lead position, and pulse generator implantation site. Unipolar DDD pacing bears a high risk of false triggering of the WCD detection algorithm. Other types of unipolar pacing and all bipolar pacing modes do not seem to mislead the WCD detection algorithm. Therefore, patients with no reprogrammable unipolar DDD pacing should not become candidates for the WCD. © 2016 Wiley Periodicals, Inc.

Downregulation of cardiac guanosine 5'-triphosphate-binding proteins in right atrium and left ventricle in pacing-induced congestive heart failure.

PubMed Central

Roth, D A; Urasawa, K; Helmer, G A; Hammond, H K

1993-01-01

The extent to which congestive heart failure (CHF) is dependent upon increased levels of the cardiac inhibitory GTP-binding protein (Gi), and the impact of CHF on the cardiac stimulatory GTP-binding protein (Gs) and mechanisms by which Gs may change remain unexplored. We have addressed these unsettled issues using pacing-induced CHF in pigs to examine physiological, biochemical, and molecular features of the right atrium (RA) and left ventricle (LV). CHF was associated with an 85 +/- 20% decrease in LV segment shortening (P < 0.001) and a 3.5-fold increase (P = 0.006) in the ED50 for isoproterenol-stimulated heart rate responsiveness. Myocardial beta-adrenergic receptor number was decreased 54% in RA (P = 0.004) and 57% in LV (P < 0.001), and multiple measures of adenylyl cyclase activity were depressed 49 +/- 8% in RA (P < 0.005), and 44 +/- 9% in LV (P < 0.001). Quantitative immunoblotting established that Gi and Gs were decreased in RA (Gi: 59% reduction; P < 0.0001; Gs: 28% reduction; P < 0.007) and LV (Gi: 35% reduction; P < 0.008; Gs: 28% reduction; P < 0.01) after onset of CHF. Reduced levels of Gi and Gs were confirmed by ADP ribosylation studies, and diminished function of Gs was established in reconstitution studies. Steady state levels for Gs alpha mRNA were increased in RA and unchanged in LV, and significantly more GS alpha was found in the supernatant (presumably cytosolic) fraction in RA and LV membrane homogenates after CHF, suggesting that increased Gs degradation, rather than decreased Gs synthesis, is the mechanism by which Gs is downregulated. We conclude that cardiac Gi content poorly predicts adrenergic responsiveness or contractile function, that decreased Gs is caused by increased degradation rather than decreased synthesis, and that alterations in beta-adrenergic receptors, adenylyl cyclase, and GTP-binding proteins are uniform in RA and LV in this model of congestive heart failure. Images PMID:8383705

Longevity of implantable cardioverter-defibrillators for cardiac resynchronization therapy in current clinical practice: an analysis according to influencing factors, device generation, and manufacturer.

PubMed

Landolina, Maurizio; Curnis, Antonio; Morani, Giovanni; Vado, Antonello; Ammendola, Ernesto; D'onofrio, Antonio; Stabile, Giuseppe; Crosato, Martino; Petracci, Barbara; Ceriotti, Carlo; Bontempi, Luca; Morosato, Martina; Ballari, Gian Paolo; Gasparini, Maurizio

2015-08-01

Device replacement at the time of battery depletion of implantable cardioverter-defibrillators (ICDs) may carry a considerable risk of complications and engenders costs for healthcare systems. Therefore, ICD device longevity is extremely important both from a clinical and economic standpoint. Cardiac resynchronization therapy defibrillators (CRT-D) battery longevity is shorter than ICDs. We determined the rate of replacements for battery depletion and we identified possible determinants of early depletion in a series of patients who had undergone implantation of CRT-D devices. We retrieved data on 1726 consecutive CRT-D systems implanted from January 2008 to March 2010 in nine centres. Five years after a successful CRT-D implantation procedure, 46% of devices were replaced due to battery depletion. The time to device replacement for battery depletion differed considerably among currently available CRT-D systems from different manufacturers, with rates of batteries still in service at 5 years ranging from 52 to 88% (log-rank test, P < 0.001). Left ventricular lead output and unipolar pacing configuration were independent determinants of early depletion [hazard ratio (HR): 1.96; 95% 95% confidence interval (CI): 1.57-2.46; P < 0.001 and HR: 1.58, 95% CI: 1.25-2.01; P < 0.001, respectively]. The implantation of a recent-generation device (HR: 0.57; 95% CI: 0.45-0.72; P < 0.001), the battery chemistry and the CRT-D manufacturer (HR: 0.64; 95% CI: 0.47-0.89; P = 0.008) were additional factors associated with replacement for battery depletion. The device longevity at 5 years was 54%. High left ventricular lead output and unipolar pacing configuration were associated with early battery depletion, while recent-generation CRT-Ds displayed better longevity. Significant differences emerged among currently available CRT-D systems from different manufacturers. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.

Low Energy Multi-Stage Atrial Defibrillation Therapy Terminates Atrial Fibrillation with Less Energy than a Single Shock

PubMed Central

Li, Wenwen; Janardhan, Ajit H.; Fedorov, Vadim V.; Sha, Qun; Schuessler, Richard B.; Efimov, Igor R.

2011-01-01

Background Implantable device therapy of atrial fibrillation (AF) is limited by pain from high-energy shocks. We developed a low-energy multi-stage defibrillation therapy and tested it in a canine model of AF. Methods and Results AF was induced by burst pacing during vagus nerve stimulation. Our novel defibrillation therapy consisted of three stages: ST1 (1-4 low energy biphasic shocks), ST2 (6-10 ultra-low energy monophasic shocks), and ST3 (anti-tachycardia pacing). Firstly, ST1 testing compared single or multiple monophasic (MP) and biphasic (BP) shocks. Secondly, several multi-stage therapies were tested: ST1 versus ST1+ST3 versus ST1+ST2+ST3. Thirdly, three shock vectors were compared: superior vena cava to distal coronary sinus (SVC>CSd), proximal coronary sinus to left atrial appendage (CSp>LAA) and right atrial appendage to left atrial appendage (RAA>LAA). The atrial defibrillation threshold (DFT) of 1BP shock was less than 1MP shock (0.55 ± 0.1 versus 1.38 ± 0.31 J; p =0.003). 2-3 BP shocks terminated AF with lower peak voltage than 1BP or 1MP shock and with lower atrial DFT than 4 BP shocks. Compared to ST1 therapy alone, ST1+ST3 lowered the atrial DFT moderately (0.51 ± 0.46 versus 0.95 ± 0.32 J; p = 0.036) while a three-stage therapy, ST1+ST2+ST3, dramatically lowered the atrial DFT (0.19 ± 0.12 J versus 0.95 ± 0.32 J for ST1 alone, p=0.0012). Finally, the three-stage therapy ST1+ST2+ST3 was equally effective for all studied vectors. Conclusions Three-stage electrotherapy significantly reduces the AF defibrillation threshold and opens the door to low energy atrial defibrillation at or below the pain threshold. PMID:21980076

Diffuse fibrosis leads to a decrease in unipolar voltage: Validation in a swine model of premature ventricular contraction-induced cardiomyopathy.

PubMed

Tanaka, Yasuaki; Rahmutula, Dolkun; Duggirala, Srikant; Nazer, Babak; Fang, Qizhi; Olgin, Jeffrey; Sievers, Richard; Gerstenfeld, Edward P

2016-02-01

Frequent premature ventricular contractions (PVCs) may lead to dilated cardiomyopathy. A leftward shift in the unipolar voltage distribution in patients with cardiomyopathy has also been described and attributed to increased fibrosis. We established a swine model of PVC-induced cardiomyopathy and assessed (1) whether an increase in left ventricular fibrosis occurs and (2) whether increased fibrosis leads to a leftward shift in the unipolar voltage distribution. Ten swine underwent implantation of ventricular pacemakers; 6 programmed to deliver a 50% PVC burden and 4 controls without pacing. Voltage maps were acquired at baseline and after 14 weeks of ventricular bigeminy. In the PVC group, left ventricular ejection fraction decreased from 67% ± 7% to 44% ± 15% (P < .05) with no change in controls (71% ± 6% to 73% ± 4%; P = .56). The fifth percentile of the bipolar and unipolar voltage distribution at baseline was 1.63 and 5.36 mV, respectively. In the control group, after 14 weeks of pacing there was no significant change in % bipolar voltage <1.5 mV (pre 1.2% vs post 2.2%; P = .34) or % unipolar voltage <5.5 mV (pre 4.0% vs post 3.5%; P = .20). In the PVC group, there was a significant increase in % unipolar voltage <5.5 mV (5.4% vs 12.6%; P < .01), with a leftward shift in the unipolar voltage distribution. Histologically, % fibrosis was increased in the PVC group (control 1.8% ± 1.3% vs PVC 3.4% ± 2.6%; P < .01). PVC-induced cardiomyopathy in swine leads to an increase in interstitial fibrosis and a leftward shift in the unipolar voltage distribution. These findings are consistent with findings in humans with PVC-induced cardiomyopathy. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Exploration of computational methods for classification of movement intention during human voluntary movement from single trial EEG.

PubMed

Bai, Ou; Lin, Peter; Vorbach, Sherry; Li, Jiang; Furlani, Steve; Hallett, Mark

2007-12-01

To explore effective combinations of computational methods for the prediction of movement intention preceding the production of self-paced right and left hand movements from single trial scalp electroencephalogram (EEG). Twelve naïve subjects performed self-paced movements consisting of three key strokes with either hand. EEG was recorded from 128 channels. The exploration was performed offline on single trial EEG data. We proposed that a successful computational procedure for classification would consist of spatial filtering, temporal filtering, feature selection, and pattern classification. A systematic investigation was performed with combinations of spatial filtering using principal component analysis (PCA), independent component analysis (ICA), common spatial patterns analysis (CSP), and surface Laplacian derivation (SLD); temporal filtering using power spectral density estimation (PSD) and discrete wavelet transform (DWT); pattern classification using linear Mahalanobis distance classifier (LMD), quadratic Mahalanobis distance classifier (QMD), Bayesian classifier (BSC), multi-layer perceptron neural network (MLP), probabilistic neural network (PNN), and support vector machine (SVM). A robust multivariate feature selection strategy using a genetic algorithm was employed. The combinations of spatial filtering using ICA and SLD, temporal filtering using PSD and DWT, and classification methods using LMD, QMD, BSC and SVM provided higher performance than those of other combinations. Utilizing one of the better combinations of ICA, PSD and SVM, the discrimination accuracy was as high as 75%. Further feature analysis showed that beta band EEG activity of the channels over right sensorimotor cortex was most appropriate for discrimination of right and left hand movement intention. Effective combinations of computational methods provide possible classification of human movement intention from single trial EEG. Such a method could be the basis for a potential brain-computer interface based on human natural movement, which might reduce the requirement of long-term training. Effective combinations of computational methods can classify human movement intention from single trial EEG with reasonable accuracy.

Atrial supply-demand balance in healthy adult pigs: coronary blood flow, oxygen extraction, and lactate production during acute atrial fibrillation.

PubMed

van Bragt, Kelly A; Nasrallah, Hussein M; Kuiper, Marion; Luiken, Joost J; Schotten, Ulrich; Verheule, Sander

2014-01-01

Little is known about how atrial oxygen supply responds to increased demand, and under which conditions it falls short (supply-demand mismatch). Here, we have investigated the vasodilator response, oxygen extraction, and lactate production of the left atrium (LA) and left ventricle (LV) in response to atrial pacing and atrial fibrillation (AF). Series A (n = 9 Dutch landrace pigs) was instrumented to measure LA and LV vascular conductance in branches of the circumflex artery. Coronary conductance reserve (CCR) was calculated as the ratio between conductance during adenosine infusion and baseline. Series B (n = 7) was instrumented with sampling catheters in LA and LV veins for determination of blood gases and lactate levels. LA CCR (1.76 ± 0.14) was significantly lower than LV CCR (3.16 ± 0.27, P = 0.002). However, basal oxygen extraction was lower in LA (27 ± 3%) than that in the LV (58 ± 6%, P = 0.0006), indicating a larger extraction reserve in the LA than that in the LV (4.68 ± 0.84 vs. 1.88 ± 0.26, P = 0.01). Atrial pacing caused an increase in LA conductance (Series A) and oxygen extraction (Series B). AF increased LA vascular conductance to 177 ± 14% at 1 min, 168 ± 14 at 5 min, and 164 ± 31% at 10 min of AF (P < 0.05 vs. baseline). Atrial oxygen extraction also increased from 26 ± 3% at baseline to 63 ± 5% (P < 0.01) at 5 min and 60 ± 11% (P < 0.01) at 10 min of AF. Arterio-venous lactate difference increased significantly (P = 0.02) during AF. In healthy pigs, the LA has a lower CCR, but a higher extraction reserve compared with the LV. Although both reserves were recruited during AF, atrial lactate production increased significantly.

Effects of angiotensin-neprilysin inhibition compared to angiotensin inhibition on ventricular arrhythmias in reduced ejection fraction patients under continuous remote monitoring of implantable defibrillator devices.

PubMed

de Diego, Carlos; González-Torres, Luis; Núñez, José María; Centurión Inda, Raúl; Martin-Langerwerf, David A; Sangio, Antonio D; Chochowski, Piotr; Casasnovas, Pilar; Blazquéz, Julio C; Almendral, Jesús

2018-03-01

Angiotensin-neprilysin inhibition compared to angiotensin inhibition decreased sudden cardiac death in patients with reduced ejection fraction heart failure (rEFHF). The precise mechanism remains unclear. The purpose of this study was to explore the effect of angiotensin-neprilysin inhibition on ventricular arrhythmias compared to angiotensin inhibition in rEFHF patients with an implantable cardioverter-defibrillator (ICD) and remote monitoring. We prospectively included 120 patients with ICD and (1) New York Heart Association functional class ≥II; (2) left ventricular ejection fraction ≤40%; and (3) remote monitoring. For 9 months, patients received 100% angiotensin inhibition with angiotensin-converting enzyme inhibitor (ACEi) or angiotensin receptor blocker (ARB), beta-blockers, and mineraloid antagonist. Subsequently, ACEi or ARB was changed to sacubitril-valsartan in all patients, who were followed for 9 months. Appropriate shocks, nonsustained ventricular tachycardia (NSVT), premature ventricular contraction (PVC) burden, and biventricular pacing percentage were analyzed. Patients were an average age of 69 ± 8 years and had mean left ventricular ejection fraction of 30.4% ± 4% (82% ischemic). Use of beta-blockers (98%), mineraloid antagonist (97%) and antiarrhythmic drugs was similar before and after sacubitril-valsartan. Sacubitril-valsartan significantly decreased NSVT episodes (5.4 ± 0.5 vs 15 ± 1.7 in angiotensin inhibition; P <.002), sustained ventricular tachycardia, and appropriate ICD shocks (0.8% vs 6.7% in angiotensin inhibition; P <.02). PVCs per hour decreased after sacubitril-valsartan (33 ± 12 vs 78 ± 15 in angiotensin inhibition; P <.0003) and was associated with increased biventricular pacing percentage (from 95% ± 6% to 98.8% ± 1.3%; P <.02). Angiotensin-neprilysin inhibition decreased ventricular arrhythmias and appropriate ICD shocks in rEFHF patients under home monitoring compared to angiotensin inhibition. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Strain, strain rate, and the force frequency relationship in patients with and without heart failure.

PubMed

Mak, Susanna; Van Spall, Harriette G C; Wainstein, Rodrigo V; Sasson, Zion

2012-03-01

The aim of this study was to examine the effect of heart rate (HR) on indices of deformation in adults with and without heart failure (HF) who underwent simultaneous high-fidelity catheterization of the left ventricle to describe the force-frequency relationship. Right atrial pacing to control HR and high-fidelity recordings of left ventricular (LV) pressure were used to inscribe the force-frequency relationship. Simultaneous two-dimensional echocardiographic imaging was acquired for speckle-tracking analysis. Thirteen patients with normal LV function and 12 with systolic HF (LV ejection fraction, 31 ± 13%) were studied. Patients with HF had depressed isovolumic contractility and impaired longitudinal strain and strain rate. HR-dependent increases in LV+dP/dt(max), the force-frequency relationship, was demonstrated in both groups (normal LV function, baseline to 100 beats/min: 1,335 ± 296 to 1,564 ± 320 mm Hg/sec, P < .0001; HF, baseline to 100 beats/min: 970 ± 207 to 1,083 ± 233 mm Hg/sec, P < .01). Longitudinal strain decreased significantly (normal LV function, baseline to 100 beats/min: 18.0 ± 3.5% to 10.8 ± 6.0%, P < .001; HF: 9.4 ± 4.1% to 7.5 ± 3.4%, P < .01). The decrease in longitudinal strain was related to a decrease in LV end-diastolic dimensions. Strain rate did not change with right atrial pacing. Despite the inotropic effect of increasing HR, longitudinal strain decreases in parallel with stroke volume as load-dependent indices of ejection. Strain rate did not reflect the modest HR-related changes in contractility; on the other hand, the use of strain rate for quantitative stress imaging is also less likely to be confounded by chronotropic responses. Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

Long-term biatrial recordings in post-operative atrial fibrillation.

PubMed

Masè, M; Graffigna, A; Sinelli, S; Pallaoro, G; Nollo, G; Ravelli, F

2010-01-01

Although atrial fibrillation (AF) is a common complication of cardiac surgery, its pathophysiology remains unclear. The study of post-operative AF demands for the recording of cardiac electrical activity in correspondence of AF onset and progression. Long-term recordings in post-surgery patients could provide this information, but, to date, have been limited to surface signals, which precludes a characterization of the arrhythmic triggers and substrate. In this study we demonstrate the feasibility of a continuous long-term recording of atrial electrical activities from the right and left atria in post-surgery patients. Local atrial epicardial electrograms are acquired by positioning temporary pacing wires in the right and left atria at the end of the intervention, while three day recordings are obtained by a digital holter recorder, adapted to epicardial signal features. The capability of the system to map local atrial activity and the possibility to obtain quantitative information on atrial rate and synchronization from the processed epicardial signals are proven in representative examples. The quantitative description of local atrial properties opens new perspective in the investigation of post-surgery AF.

The initial electrocardiogram during admission for myocardial infarction. Use as a predictor of clinical course and facility utilization.

PubMed

Stark, M E; Vacek, J L

1987-05-01

The first electrocardiogram obtained on presentation for suspected myocardial infarction was examined for its usefulness in predicting clinical course and facility use. We studied 221 patients consecutively admitted to a nonuniversity hospital coronary care unit. High-risk patients were identified if the electrocardiographic diagnoses included myocardial infarction, ischemia, left ventricular hypertrophy, left bundle-branch block, or paced rhythm. These 63 patients (29% of total) had significantly greater incidences of serious events, need for procedures, and death than low-risk patients whose initial electrocardiograms did not carry the above diagnoses. Patients with a low-risk initial electrocardiogram may not require the facilities of a coronary care unit and perhaps could be safely observed in an intermediate care area. However, many hospitals do not have an intermediate care facility available, and in those that do, daily costs may not be markedly different than for treatment in a coronary care unit. Whether these low-risk patients could be safely treated in general medicine beds, where potential cost savings would be much greater, is unknown.

Pyloric obstruction secondary to epicardial pacemaker implantation: a case report.

PubMed

Bedoya Nader, G; Kellihan, H B; Bjorling, D E; McAnulty, J

2017-02-01

A 10-year old Lhasa Apso dog was presented for an acute history of exercise intolerance and hind limb weakness. High grade second degree atrioventricular block with an atrial rate of 200 beats per minute, ventricular rate of 40 beats per minute and an intermittent ventricular escape rhythm, was diagnosed on electrocardiograph. A transdiaphragmatic, unipolar, epicardial pacemaker was implanted without immediate surgical complications. Severe vomiting was noted 12 h post-operatively. Abdominal ultrasound and a barium study supported a diagnosis of pyloric outflow obstruction and exploratory abdominal surgery was performed. The pyloric outflow tract appeared normal and no other causes of an outflow obstruction were identified. The epicardial generator was repositioned from the right to the left abdominal wall. Pyloric cell pacing was presumed to be the cause for the pyloric obstruction and severe vomiting, and this was thought to be due to close proximity of the pacemaker generator to the pylorus situated in the right abdominal wall. Repositioning of the pulse generator to the left abdominal wall resulted in resolution of vomiting. Copyright © 2016 Elsevier B.V. All rights reserved.

Transcatheter aortic valve-in-valve implantation of a CoreValve in a JenaValve prosthesis: a case report.

PubMed

Lotfi, Shahram; Becker, Michael; Moza, Ajay; Autschbach, Rüdiger; Marx, Nikolaus; Schröder, Jörg

2017-09-10

Transcatheter aortic valve implantation has become an accepted treatment modality for inoperable or high-risk surgical patients with symptomatic severe aortic stenosis. We report the case of a 70-year-old white man who was treated for severe symptomatic aortic regurgitation using transcatheter aortic valve implantation from the apical approach. Because of recurrent cardiac decompensation 4 weeks after implantation he underwent the implantation of a left ventricular assist device system. A year later echocardiography showed a severe transvalvular central insufficiency. Our heart team decided to choose a valve-in-valve approach while reducing the flow rate of left ventricular assist device to minimum and pacing with a frequency of 140 beats/minute. There was an excellent result and our patient is doing well with no relevant insufficiency of the aortic valve at 12-month follow-up. This is the first report about a successful treatment of a stenotic JenaValve using a CoreValve Evolut R; the use of a CoreValve Evolut R prosthesis may be an optimal option for valve-in-valve procedures.

Effects of home-based pulmonary rehabilitation with a metronome-guided walking pace in chronic obstructive pulmonary disease.

PubMed

Lee, Sung-soon; Kim, Changhwan; Jin, Young-Soo; Oh, Yeon-Mok; Lee, Sang-Do; Yang, Yun Jun; Park, Yong Bum

2013-05-01

Despite documented efficacy and recommendations, pulmonary rehabilitation (PR) in chronic obstructive pulmonary disease (COPD) has been underutilized. Home-based PR was proposed as an alternative, but there were limited data. The adequate exercise intensity was also a crucial issue. The aim of this study was to investigate the effects of home-based PR with a metronome-guided walking pace on functional exercise capacity and health-related quality of life (HRQOL) in COPD. The subjects participated in a 12-week home-based PR program. Exercise intensity was initially determined by cardiopulmonary exercise test, and was readjusted (the interval of metronome beeps was reset) according to submaximal endurance test. Six-minute walk test, pulmonary function test, cardiopulmonary exercise test, and St. George's Respiratory Questionnaire (SGRQ) were done before and after the 12-week program, and at 6 months after completion of rehabilitation. Thirty-three patients participated in the program. Six-minute walking distance was significantly increased (48.8 m; P = 0.017) and the SGRQ score was also improved (-15; P < 0.001) over the six-month follow-up period after rehabilitation. There were no significant differences in pulmonary function and peak exercise parameters. We developed an effective home-based PR program with a metronome-guided walking pace for COPD patients. This rehabilitation program may improve functional exercise capacity and HRQOL.

Variables affecting the manifestation of and intensity of pacing behavior: A preliminary case study in zoo-housed polar bears.

PubMed

Cless, Isabelle T; Lukas, Kristen E

2017-09-01

High-speed video analysis was used to quantify two aspects of gait in 10 zoo-housed polar bears. These two variables were then examined as to how they differed in the conditions of pacing versus locomoting for each bear. Percent difference calculations measured the difference between pacing and locomoting data for each bear. We inferred that the higher the percent difference between pacing and locomoting in a given subject, the more intense the pacing may be. The percent difference values were analyzed alongside caregiver survey data defining the locations, frequency, and anticipatory nature of pacing in each bear, as well as each bear's age and sex, to determine whether any variables were correlated. The frequency and intensity of pacing behavior were not correlated. However, location of pacing was significantly correlated both with the subjects' age and whether or not the subject was classified as an anticipatory pacer. Bears appeared to select specific spots within their exhibits to pace, and the location therefore seemed tied to underlying motivation for the behavior. Additionally, bears that were classified in the survey as pacing anticipatorily displayed significantly more intense pacing behavior as quantified by gait analysis. © 2017 Wiley Periodicals, Inc.

42 CFR 460.122 - PACE organization's appeals process.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Rights § 460.122 PACE organization's appeals process. For purposes...

42 CFR 460.122 - PACE organization's appeals process.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Rights § 460.122 PACE organization's appeals process. For purposes...

42 CFR 460.170 - Reinstatement in PACE.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.170 Reinstatement in PACE. (a) A previously...

42 CFR 460.170 - Reinstatement in PACE.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Participant Enrollment and Disenrollment § 460.170 Reinstatement in PACE. (a) A previously...

Effects of pacing magnitudes and forms on bistability width in a modeled ventricular tissue

NASA Astrophysics Data System (ADS)

Huang, Xiaodong; Liu, Xuemei; Zheng, Lixian; Mi, Yuanyuan; Qian, Yu

2013-07-01

Bistability in periodically paced cardiac tissue is relevant to cardiac arrhythmias and its control. In the present paper, one-dimensional tissue of the phase I Luo-Rudy model is numerically investigated. The effects of various parameters of pacing signals on bistability width are studied. The following conclusions are obtained: (i) Pacing can be classified into two types: pulsatile and sinusoidal types. Pulsatile pacing reduces bistability width as its magnitude is increased. Sinusoidal pacing increases the width as its amplitude is increased. (ii) In a pacing period the hyperpolarizing part plays a more important role than the depolarizing part. Variations of the hyperpolarizing ratio in a period evidently change the width of bistability and its variation tendency. (iii) A dynamical mechanism is proposed to qualitatively explain the phenomena, which reveals the reason for the different effects of pulsatile and sinusoidal pacing on bistability. The methods for changing bistability width by external pacing may help control arrhythmias in cardiology.

The Positive Effects of Priming Exercise on Oxygen Uptake Kinetics and High-Intensity Exercise Performance Are Not Magnified by a Fast-Start Pacing Strategy in Trained Cyclists

PubMed Central

Caritá, Renato Aparecido Corrêa; Greco, Camila Coelho; Denadai, Benedito Sérgio

2014-01-01

The purpose of this study was to determine both the independent and additive effects of prior heavy-intensity exercise and pacing strategies on the VO2 kinetics and performance during high-intensity exercise. Fourteen endurance cyclists (VO2max  = 62.8±8.5 mL.kg−1.min−1) volunteered to participate in the present study with the following protocols: 1) incremental test to determine lactate threshold and VO2max; 2) four maximal constant-load tests to estimate critical power; 3) six bouts of exercise, using a fast-start (FS), even-start (ES) or slow-start (SS) pacing strategy, with and without a preceding heavy-intensity exercise session (i.e., 90% critical power). In all conditions, the subjects completed an all-out sprint during the final 60 s of the test as a measure of the performance. For the control condition, the mean response time was significantly shorter (p<0.001) for FS (27±4 s) than for ES (32±5 s) and SS (32±6 s). After the prior exercise, the mean response time was not significantly different among the paced conditions (FS = 24±5 s; ES = 25±5 s; SS = 26±5 s). The end-sprint performance (i.e., mean power output) was only improved (∼3.2%, p<0.01) by prior exercise. Thus, in trained endurance cyclists, an FS pacing strategy does not magnify the positive effects of priming exercise on the overall VO2 kinetics and short-term high-intensity performance. PMID:24740278

Spanish Pacemaker Registry. Thirteenth Official Report of the Spanish Society of Cardiology Working Group on Cardiac Pacing (2015).

PubMed

Pombo Jiménez, Marta; Cano Pérez, Óscar; Fidalgo Andrés, María Luisa; Lorente Carreño, Diego; Coma Samartín, Raúl

2016-12-01

We describe the results of the analysis of the devices implanted and conveyed to the Spanish Pacemaker Registry in 2015. The report is based on the processing of information provided by the European Pacemaker Patient Identification Card. We received information from 111 hospitals, with a total of 12 555 cards, representing 32.1% of all the estimated activity. The use of conventional generators and resynchronization devices was 820 and 73 units per million population, respectively. The mean age of the patients receiving an implantation was 77.7 years, and more than 50% of the devices were implanted in patients over 80 years of age. Overall, 58.6% of the implants and 58.8% of the replacements were performed in men. All of the endocardial leads employed were bipolar, 81.5% had an active fixation system, and 16.5% were compatible with magnetic resonance. Although dual chamber sequential pacing continues to be more widespread, pacing with VVI/R mode is used because up to 23.8% of the patients with sinus node disease are in sinus rhythm, as are 24.1% of those with atrioventricular block. The total use of pacemaker generators in Spain has increased by about 5% with respect to 2014. The majority of the leads implanted are of active fixation, and less than 20% are protected from magnetic resonance. The factors directly related to the selection of pacing mode are age and sex. In around 20% of patients, the choice of the pacing mode could be improved. Copyright © 2016 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

Predictors of temporary epicardial pacing wires use after valve surgery

PubMed Central

2014-01-01

Background Although temporary cardiac pacing is infrequently needed, temporary epicardial pacing wires are routinely inserted after valve surgery. As they are associated with infrequent, but life threatening complications, and the decreased need for postoperative pacing in a group of low risk patients; this study aims to identify the predictors of temporary cardiac pacing after valve surgery. Methods A retrospective analysis of data collected prospectively on 400 consecutive valve surgery patients between May 2002 and December 2012 was performed. Patients were grouped according to avoidance or insertion of temporary pacing wires, and were further subdivided according to temporary cardiac pacing need. Multiple logistic regression was used to determine the predictors of temporary cardiac pacing. Results 170 (42.5%) patients did not have insertion of temporary pacing wires and none of them needed temporary pacing. 230 (57.5%) patients had insertion of temporary pacing wires and among these, only 55 (23.9%) required temporary pacing who were compared with the remaining 175 (76.1%) patients in the main analysis. The determinants of temporary cardiac pacing (adjusted odds ratios; 95% confidence interval) were as follows: increased age (1.1; 1.1, 1.3, p = 0.002), New York Heart Association class III- IV (5.6; 1.6, 20.2, p = 0.008) , pulmonary artery pressure ≥ 50 mmHg (22.0; 3.4, 142.7, p = 0.01), digoxin use (8.0; 1.3, 48.8, p = 0.024), multiple valve surgery (13.5; 1.5, 124.0, p = 0.021), aorta cross clamp time ≥ 60 minutes (7.8; 1.6, 37.2, p = 0.010), and valve annulus calcification (7.9; 2.0, 31.7, p = 0.003). Conclusion Although limited by sample size, the present results suggest that routine use of temporary epicardial pacing wires after valve surgery is only necessary for high risk patients. Preoperative identification and aggressive management of predictors of temporary cardiac pacing and the possible modulation of intraoperative techniques can decrease the need of temporary cardiac pacing. Prospective randomized controlled studies on a larger number of patients are necessary to draw solid conclusions regarding the selective use of temporary epicardial pacing wires in valve surgery. PMID:24521215

42 CFR 460.30 - Program agreement requirement.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.30 Program agreement requirement. (a) A PACE organization must...

42 CFR 460.30 - Program agreement requirement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Program Agreement § 460.30 Program agreement requirement. (a) A PACE organization must...

42 CFR 460.50 - Termination of PACE program agreement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Sanctions, Enforcement Actions, and Termination § 460.50 Termination of PACE...

42 CFR 460.50 - Termination of PACE program agreement.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Sanctions, Enforcement Actions, and Termination § 460.50 Termination of PACE...

42 CFR 460.180 - Medicare payment to PACE organizations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Payment § 460.180 Medicare payment to PACE organizations. (a) Principle of...

DefenseLink Special: Travels with Pace, March 2006

Science.gov Websites

Us Travels with Pace Chairman of the Joint Chiefs of Staff Marine Gen. Peter Pace U.S. Marine Gen . Peter Pace, chairman of the Joint Chiefs of Staff, speaks to students attending the Turkish War College U.S. Air Force Staff Sgt. D. Myles Cullen Hi-Res Pace Wraps Up Visit to Allied Nations WASHINGTON

Effect of short-term rapid ventricular pacing followed by pacing interruption on arterial blood pressure in healthy pigs and pigs with tachycardiomyopathy.

PubMed

Skrzypczak, P; Zyśko, D; Pasławska, U; Noszczyk-Nowak, A; Janiszewski, A; Gajek, J; Nicpoń, J; Kiczak, L; Bania, J; Zacharski, M; Tomaszek, A; Jankowska, E A; Ponikowski, P; Witkiewicz, W

2014-01-01

Ventricular tachycardia may lead to haemodynamic deterioration and, in the case of long term persistence, is associated with the development of tachycardiomyopathy. The effect of ventricular tachycardia on haemodynamics in individuals with tachycardiomyopathy, but being in sinus rhythm has not been studied. Rapid ventricular pacing is a model of ventricular tachycardia. The aim of this study was to determine the effect of rapid ventricular pacing on blood pressure in healthy animals and those with tachycardiomyopathy. A total of 66 animals were studied: 32 in the control group and 34 in the study group. The results of two groups of examinations were compared: the first performed in healthy animals (133 examinations) and the second performed in animals paced for at least one month (77 examinations). Blood pressure measurements were taken during chronic pacing--20 min after onset of general anaesthesia, in baseline conditions (20 min after pacing cessation or 20 min after onset of general anaesthesia in healthy animals) and immediately after short-term rapid pacing. In baseline conditions significantly higher systolic and diastolic blood pressure was found in healthy animals than in those with tachycardiomyopathy. During an event of rapid ventricular pacing, a significant decrease in systolic and diastolic blood pressure was found in both groups of animals. In the group of chronically paced animals the blood pressure was lower just after restarting ventricular pacing than during chronic pacing. Cardiovascular adaptation to ventricular tachycardia develops with the length of its duration. Relapse of ventricular tachycardia leads to a blood pressure decrease more pronounced than during chronic ventricular pacing.

Encyclopedia Publishing: An Update

ERIC Educational Resources Information Center

Kister, Kenneth

1978-01-01

Problems discussed include difficulty of keeping pace with the "knowledge explosion" and rapidly changing social attitudes, higher production costs vs. declining sales, consumer dissatisfaction with sales tactics, and intellectual snobbery towards the product. Trends are the single volume edition, improved sales techniques, and publisher…

Anatomical approach to permanent His bundle pacing: Optimizing His bundle capture.

PubMed

Vijayaraman, Pugazhendhi; Dandamudi, Gopi

2016-01-01

Permanent His bundle pacing is a physiological alternative to right ventricular pacing. In this article we describe our approach to His bundle pacing in patients with AV nodal and intra-Hisian conduction disease. It is essential for the implanters to understand the anatomic variations of the His bundle course and its effect on the type of His bundle pacing achieved. We describe several case examples to illustrate our anatomical approach to permanent His bundle pacing in this article. Copyright © 2016 Elsevier Inc. All rights reserved.

Optimizing local capture of atrial fibrillation by rapid pacing: study of the influence of tissue dynamics.

PubMed

Uldry, Laurent; Virag, Nathalie; Jacquemet, Vincent; Vesin, Jean-Marc; Kappenberger, Lukas

2010-12-01

While successful termination by pacing of organized atrial tachycardias has been observed in patients, rapid pacing of AF can induce a local capture of the atrial tissue but in general no termination. The purpose of this study was to perform a systematic evaluation of the ability to capture AF by rapid pacing in a biophysical model of the atria with different dynamics in terms of conduction velocity (CV) and action potential duration (APD). Rapid pacing was applied during 30 s at five locations on the atria, for pacing cycle lengths in the range 60-110% of the mean AF cycle length (AFCL(mean)). Local AF capture could be achieved using rapid pacing at pacing sites located distal to major anatomical obstacles. Optimal pacing cycle lengths were found in the range 74-80% AFCL(mean) (capture window width: 14.6 ± 3% AFCL(mean)). An increase/decrease in CV or APD led to a significant shrinking/stretching of the capture window. Capture did not depend on AFCL, but did depend on the atrial substrate as characterized by an estimate of its wavelength, a better capture being achieved at shorter wavelengths. This model-based study suggests that a proper selection of the pacing site and cycle length can influence local capture results and that atrial tissue properties (CV and APD) are determinants of the response to rapid pacing.

42 CFR 460.24 - Limit on number of PACE program agreements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.24 Limit on number of...

42 CFR 460.24 - Limit on number of PACE program agreements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PACE Organization Application and Waiver Process § 460.24 Limit on number of...

Effects of septal pacing on P wave characteristics: the value of three-dimensional echocardiography.

PubMed

Szili-Torok, Tamas; Bruining, Nico; Scholten, Marcoen; Kimman, Geert-Jan; Roelandt, Jos; Jordaens, Luc

2003-01-01

Interatrial septum (IAS) pacing has been proposed for the prevention of paroxysmal atrial fibrillation. IAS pacing is usually guided by fluoroscopy and P wave analysis. The authors have developed a new approach for IAS pacing using intracardiac echocardiography (ICE), and examined its effects on P wave characteristics. Cross-sectional images are acquired during pullback of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram- and respiration-gated technique. The right atrium and IAS are then three-dimensionally reconstructed, and the desired pacing site is selected. After lead placement and electrical testing, another three-dimensional reconstruction is performed to verify the final lead position. The study included 14 patients. IAS pacing was achieved at seven suprafossal (SF) and seven infrafossal (IF) lead locations, all confirmed by three-dimensional imaging. IAS pacing resulted in a significant reduction of P wave duration as compared to sinus rhythm (99.7 +/- 18.7 vs 140.4 +/- 8.8 ms; P < 0.01). SF pacing was associated with a greater reduction of P wave duration than IF pacing (56.1 +/- 9.9 vs 30.2 +/- 13.6 ms; P < 0.01). P wave dispersion remained unchanged during septal pacing as compared to sinus rhythm (21.4 +/- 16.1 vs 13.5 +/- 13.9 ms; NS). Three-dimensional intracardiac echocardiography can be used to guide IAS pacing. SF pacing was associated with a greater decrease in P wave duration, suggesting that it is a preferable location to decrease interatrial conduction delay.

Pacing a data transfer operation between compute nodes on a parallel computer

DOEpatents

Blocksome, Michael A [Rochester, MN

2011-09-13

Methods, systems, and products are disclosed for pacing a data transfer between compute nodes on a parallel computer that include: transferring, by an origin compute node, a chunk of an application message to a target compute node; sending, by the origin compute node, a pacing request to a target direct memory access (`DMA`) engine on the target compute node using a remote get DMA operation; determining, by the origin compute node, whether a pacing response to the pacing request has been received from the target DMA engine; and transferring, by the origin compute node, a next chunk of the application message if the pacing response to the pacing request has been received from the target DMA engine.

Comparative Efficacy of Nebivolol and Metoprolol to Prevent Tachycardia-Induced Cardiomyopathy in a Porcine Model.

PubMed

Nazeri, Alireza; Elayda, MacArthur A; Segura, Ana Maria; Stainback, Raymond F; Nathan, Joanna; Lee, Vei-Vei; Bove, Christina; Sampaio, Luiz; Grace, Brian; Massumi, Ali; Razavi, Mehdi

2016-12-01

Chronic tachycardia is a well-known cause of nonischemic cardiomyopathy. We hypothesized that nebivolol, a β-blocker with nitric oxide activity, would be superior to a pure β-blocker in preventing tachycardia-induced cardiomyopathy in a porcine model. Fifteen healthy Yucatan pigs were randomly assigned to receive nebivolol, metoprolol, or placebo once a day. All pigs underwent dual-chamber pacemaker implantation. The medication was started the day after the pacemaker implantation. On day 7 after implantation, each pacemaker was set at atrioventricular pace (rate, 170 beats/min), and the pigs were observed for another 7 weeks. Transthoracic echocardiograms, serum catecholamine levels, and blood chemistry data were obtained at baseline and at the end of the study. At the end of week 8, the pigs were euthanized, and complete histopathologic studies were performed. All the pigs developed left ventricular cardiomyopathy but remained hemodynamically stable and survived to the end of the study. The mean left ventricular ejection fraction decreased from baseline by 34%, 20%, and 20% in the nebivolol, metoprolol, and placebo groups, respectively. These changes did not differ significantly among the 3 groups ( P =0.51). Histopathologic analysis revealed mild left ventricular perivascular fibrosis with cardiomyocyte hypertrophy in 14 of the 15 pigs. Both nebivolol and metoprolol failed to prevent cardiomyopathy in our animal model of persistent tachycardia and a high catecholamine state.

Tricuspid valve and percutaneous approach: No longer the forgotten valve!

PubMed

Bouleti, Claire; Juliard, Jean-Michel; Himbert, Dominique; Iung, Bernard; Brochet, Eric; Urena, Marina; Dilly, Marie-Pierre; Ou, Phalla; Nataf, Patrick; Vahanian, Alec

2016-01-01

Tricuspid valve disease is mainly represented by tricuspid regurgitation (TR), which is a predictor of poor outcome. TR is usually secondary, caused by right ventricle pressure or volume overload, the leading cause being left-sided heart valve diseases. Tricuspid surgery for severe TR is recommended during left valve surgery, and consists of either a valve replacement or, most often, a tricuspid repair with or without prosthetic annuloplasty. When TR persists or worsens after left valvular surgery, redo isolated tricuspid surgery is associated with high mortality. In addition, a sizeable proportion of patients present with tricuspid surgery deterioration over time, and need a reintervention, which is associated with high morbi-mortality rates. In this context, and given the recent major breakthrough in the percutaneous treatment of aortic and mitral valve diseases, the tricuspid valve appears an appealing challenge, although it raises specific issues. The first applications of transcatheter techniques for tricuspid valve disease were valve-in-valve and valve-in-ring implantation for degenerated bioprosthesis or ring annuloplasty. Some concerns remain regarding prosthesis sizing, rapid ventricular pacing and the best approach, but these procedures appear to be safe and effective. More recently, bicuspidization using a transcatheter approach for the treatment of native tricuspid valve has been published, in two patients. Finally, other devices are in preclinical development. Copyright © 2015 Elsevier Masson SAS. All rights reserved.