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Sample records for atrial flutter ablation

  1. Late atypical atrial flutter after ablation of atrial fibrillation.

    PubMed

    Ferreira, Raquel; Primo, João; Adão, Luís; Gonzaga, Anabela; Gonçalves, Helena; Santos, Rui; Fonseca, Paulo; Santos, José; Gama, Vasco

    2016-10-01

    Cardiac surgery for structural heart disease (often involving the left atrium) and radiofrequency catheter ablation of atrial fibrillation have led to an increased incidence of regular atrial tachycardias, often presenting as atypical flutters. This type of flutter is particularly common after pulmonary vein isolation, especially after extensive atrial ablation including linear lesions and/or defragmentation. The authors describe the case of a 51-year-old man, with no relevant medical history, referred for a cardiology consultation in 2009 for paroxysmal atrial fibrillation. After failure of antiarrhythmic therapy, he underwent catheter ablation, with criteria of acute success. Three years later he again suffered palpitations and atypical atrial flutter was documented. The electrophysiology study confirmed the diagnosis of atypical left flutter and reappearance of electrical activity in the right inferior pulmonary vein. This vein was again ablated successfully and there has been no arrhythmia recurrence to date. In an era of frequent catheter ablation it is essential to understand the mechanism of this arrhythmia and to recognize such atypical flutters.

  2. Electrophysiologic basis of catheter ablation in atrial flutter.

    PubMed

    Touboul, P; Saoudi, N; Atallah, G; Kirkorian, G

    1989-12-05

    A reentrant mechanism is believed to be responsible for atrial flutter. The recent development of the entrainment criteria further supports this theory, and there is a general consensus that circus movement is the underlying abnormality that supports this arrhythmia. In most clinical studies, abnormal fragmented (or double spike) electrograms, suggesting the presence of areas of localized slowing of conduction or block, have been reported. They are almost always recorded in the lower and posterior portion of the right interatrial septum, but also frequently in the high lateral portion of the right atrium. The determination of their involvement in the reentry pathway is important for designing curative procedures such as surgery or ablation. The low atrial septal area surrounding the mouth of the coronary sinus was suspected as being the critical area of slow conduction in atrial flutter. Rapid pacing at that site can yield a surface electrocardiographic pattern similar to the clinically occurring arrhythmias. Additionally, the flutter circuit can be accelerated during atrial pacing at fixed and slightly faster rates than the intrinsic tachycardia rate--the so-called entrainment phenomenon. When entrainment criteria are fulfilled, tachycardia termination being by definition ruled out, any concomitant recorded local type II block identifies an area that must be outside the circuit. Such local block may be recorded either spontaneously or during entrainment and therefore helps in identifying atrial slow conduction areas that do not belong to the reentrant path. This approach was applied to identify the optimal ablation site in 8 patients with long-standing drug resistant atrial flutter. In 7 of 8 patients, we were able to identify a fragmented potential in the low posteroseptal area during sustained atrial flutter.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Healthcare Utilization and Clinical Outcomes after Catheter Ablation of Atrial Flutter

    PubMed Central

    Dewland, Thomas A.; Glidden, David V.; Marcus, Gregory M.

    2014-01-01

    Atrial flutter ablation is associated with a high rate of acute procedural success and symptom improvement. The relationship between ablation and other clinical outcomes has been limited to small studies primarily conducted at academic centers. We sought to determine if catheter ablation of atrial flutter is associated with reductions in healthcare utilization, atrial fibrillation, or stroke in a large, real world population. California Healthcare Cost and Utilization Project databases were used to identify patients undergoing atrial flutter ablation between 2005 and 2009. The adjusted association between atrial flutter ablation and healthcare utilization, atrial fibrillation, or stroke was investigated using Cox proportional hazards models. Among 33,004 patients with a diagnosis of atrial flutter observed for a median of 2.1 years, 2,733 (8.2%) underwent catheter ablation. Atrial flutter ablation significantly lowered the adjusted risk of inpatient hospitalization (HR 0.88, 95% CI 0.84–0.92, p<0.001), emergency department visits (HR 0.60, 95% CI 0.54–0.65, p<0.001), and overall hospital-based healthcare utilization (HR 0.94, 95% CI 0.90–0.98, p = 0.001). Atrial flutter ablation was also associated with a statistically significant 11% reduction in the adjusted hazard of atrial fibrillation (HR 0.89, 95% CI 0.81–0.97, p = 0.01). Risk of acute stroke was not significantly reduced after ablation (HR 1.09, 95% CI 0.81–1.45, p = 0.57). In a large, real world population, atrial flutter ablation was associated with significant reductions in hospital-based healthcare utilization and a reduced risk of atrial fibrillation. These findings support the early use of catheter ablation for the treatment of atrial flutter. PMID:24983868

  4. Restoration of Atrial Mechanical Function after Successful Radio-Frequency Catheter Ablation of Atrial Flutter

    PubMed Central

    Rhee, Kyoung-Suk; Kang, Duk-Hyun; Song, Jae-Kwan; Nam, Gi-Byoung; Choi, Kee-Joon; Kim, You-Ho

    2001-01-01

    Background: Atrial mechanical dysfunction and its recovery time course after successful radiofrequency ablation of chronic atrial flutter (AFL) has been largely unknown. We serially evaluated left atrial function by echocardiography after successful ablation of chronic atrial flutter. Methods: In 13 patients with chronic AFL, mitral E wave A wave, and the ratio of A/E velocity were measured at 1 day, 1 month, 3 months and 6–12 months after successful radiofrequency (RF) ablation. Doppler tissue imaging (DTI) technique was also used to avoid load-dependent variation in the flow velocity pattern. Results: Left atrial mechanical function, assessed by A wave velocity and the annular motion, was depressed at 1 day, but improved significantly at 1 month and maintained through 6–12 months after the ablation. Left atrial size did not change significantly. Conclusion: Left atrial mechanical function was depressed immediately after successful RF ablation of chronic AFL, but it improved significantly after 1 month and was maintained over one year. PMID:11590904

  5. Identification and ablation of atypical atrial flutter. Entrainment pacing combined with electroanatomic mapping.

    PubMed

    Horlitz, M; Schley, P; Shin, D-I; Ghouzi, A; Sause, A; Wehner, M; Müller, M; Klein, R M; Bufe, A; Gülker, H

    2004-06-01

    Differentiation between typical and atypical atrial flutter solely based upon surface ECG pattern may be limited. However, successful ablation of atrial flutter depends on the exact identification of the responsible re-entrant circuit and its critical isthmus. Between August 2001 and June 2003, we performed conventional entrainment pacing within the cavotricuspid isthmus in 71 patients with sustained atrial flutter. In patients with positive entrainment we considered the arrhythmia as typical flutter and treated them with conventional ablation of the cavotricuspid isthmus. As a consequence of negative entrainment we performed 3D-electroanatomic activation mapping (CARTO trade mark ). Conventional ablation of the right atrial isthmus was successful in all patients (n = 54) with positive entrainment. We performed electroanatomic mapping in the remaining 17 patients (14 male; age 60.9 +/- 16 years) resulting in the identification of 6 cases with typical and 11 cases with atypical flutter. Therefore, entrainment pacing was able to predict the true presence of typical atrial flutter in 91.5%. Atypical flutter was right sided in 4 patients and left sided in 7 cases. Electrically silent ("low voltage") areas probably demonstrating atrial myopathy were identified in all cases with left sided and in 2 patients with right sided flutter. In these patients targets for ablation lines were located between silent areas and anatomic barriers (inferior pulmonary veins, mitral respectively tricuspid annulus, or vena cava inferior). In 1 patient, the investigation was stopped due to variable ECG pattern and atrial cycle lengths. In the remaining cases, ablation was acutely successful. One patient, after surgical closure of a ventricular septal defect, demonstrated a dual-loop intra-atrial reentry tachycardia dependent on two different isthmuses. This arrhythmia required ablation of those distinct isthmuses to be interrupted. After a mean follow-up of 8.8 +/- 3.4 months, there was one

  6. Voltage-guided ablation technique for cavotricuspid isthmus-dependent atrial flutter: refining the continuous line.

    PubMed

    Jacobsen, Peter K; Klein, George J; Gula, Lorne J; Krahn, Andrew D; Yee, Raymond; Leong-Sit, Peter; Mechulan, Alexis; Skanes, Allan C

    2012-06-01

    Ablation of the cavotricuspid isthmus has become first-line therapy for "isthmus-dependent" atrial flutter. The goal of ablation is to produce bidirectional cavotricuspid isthmus block. Traditionally, this has been obtained by creation of a complete ablation line across the isthmus from the ventricular end to the inferior vena cava. This article describes an alternative method used in our laboratory. There is substantial evidence that conduction across the isthmus occurs preferentially over discrete separate bundles of tissue. Consequently, voltage-guided ablation targeting only these bundles with large amplitude atrial electrograms results in a highly efficient alternate method for the interruption of conduction across the cavotricuspid isthmus. Understanding the bundle structure of conduction over the isthmus facilitates more flexible approaches to its ablation and targeting maximum voltages in our hands has resulted in reduction of ablation time and fewer recurrences.

  7. Anatomic Guidance For Ablation: Atrial Flutter, Fibrillation, and Outflow Tract Ventricular Tachycardia

    PubMed Central

    Sehar, Nandini; Mears, Jennifer; Bisco, Susan; Patel, Sandeep; Lachman, Nirusha; Asirvatham, Samuel J

    2010-01-01

    After initial documentation of excellent efficacy with radiofrequency ablation, this procedure is being performed increasingly in more complex situations and for more difficult arrhythmia. In these circumstances, an accurate knowledge of the anatomic basis for the ablation procedure will help maintain this efficacy and improve safety. In this review, we discuss the relevant anatomy for electrophysiology interventions for typical right atrial flutter, atrial fibrillation, and outflow tract ventricular tachycardia. In the pediatric population, maintaining safety is a greater challenge, and here again, knowing the neighboring and regional anatomy of the arrhythmogenic substrate for these arrhythmias may go a long way in preventing complications. PMID:20811537

  8. Acute myocardial infarction after radiofrequency catheter ablation of typical atrial flutter.

    PubMed

    Yune, Sehyo; Lee, Woo Joo; Hwang, Ji-won; Kim, Eun; Ha, Jung Min; Kim, June Soo

    2014-02-01

    A 53-yr-old man underwent radiofrequency ablation to treat persistent atrial flutter. After the procedure, the chest pain was getting worse, and the electrocardiogram showed ST-segment elevation in inferior leads with reciprocal changes. Immediate coronary angiography showed total occlusion with thrombi at the distal portion of the right coronary artery, which was very close to the ablation site. Intervention with thrombus aspiration and balloon dilatation was successful, and the patient recovered without any kind of sequelae. Although the exact mechanism is obscure, the most likely explanation is a thermal injury to the vascular wall that ruptured into the lumen and formed thrombus. Vasospasm and thromboembolism can also be other possibilities. This case raise the alarm to cardiologists who perform radiofrequency ablation to treat various kinds of cardiac arrhythmias, in that myocardial infarction has been rarely considered one of the complications.

  9. Efficacy comparison between cryoablation and radiofrequency ablation for patients with cavotricuspid valve isthmus dependent atrial flutter: a meta-analysis

    NASA Astrophysics Data System (ADS)

    Chen, Yi-He; Lin, Hui; Xie, Cheng-Long; Zhang, Xiao-Ting; Li, Yi-Gang

    2015-06-01

    We perform this meta-analysis to compare the efficacy and safety of cryoablation versus radiofrequency ablation for patients with cavotricuspid valve isthmus dependent atrial flutter. By searching EMBASE, MEDLINE, PubMed and Cochrane electronic databases from March 1986 to September 2014, 7 randomized clinical trials were included. Acute (risk ratio[RR]: 0.93; P = 0.14) and long-term (RR: 0.94; P = 0.08) success rate were slightly lower in cryoablation group than in radiofrequency ablation group, but the difference was not statistically significant. Additionally, the fluoroscopy time was nonsignificantly reduced (weighted mean difference[WMD]: -2.83 P = 0.29), whereas procedure time was significantly longer (WMD: 25.95; P = 0.01) in cryoablation group compared with radiofrequency ablation group. Furthermore, Pain perception during the catheter ablation was substantially less in cryoabaltion group than in radiofrequency ablation group (standardized mean difference[SMD]: -2.36 P < 0.00001). Thus, our meta-analysis demonstrated that cryoablation and radiofrequency ablation produce comparable acute and long-term success rate for patients with cavotricuspid valve isthmus dependent atrial flutter. Meanwhile, cryoablation ablation tends to reduce the fluoroscopy time and significantly reduce pain perception in cost of significantly prolonged procedure time.

  10. Acute success and short-term follow-up of catheter ablation of isthmus-dependent atrial flutter; a comparison of 8 mm tip radiofrequency and cryothermy catheters

    PubMed Central

    Janse, P.; Alings, M.; Scholten, M. F.; Mekel, J. M.; Miltenburg, M.; Jessurun, E.; Jordaens, L.

    2008-01-01

    Objectives To compare the acute success and short-term follow-up of ablation of atrial flutter using 8 mm tip radiofrequency (RF) and cryocatheters. Methods Sixty-two patients with atrial flutter were randomized to RF or cryocatheter (cryo) ablation. Right atrial angiography was performed to assess the isthmus. End point was bidirectional isthmus block on multiple criteria. A pain score was used and the analgesics were recorded. Patients were followed for at least 3 months. Results The acute success rate for RF was 83% vs 69% for cryo (NS). Procedure times were similar (mean 144 ± 48 min for RF, vs 158 ± 49 min for cryo). More applications were given with RF than with cryo (26 ± 17 vs. 18 ± 10, p < 0.05). Fluoroscopy time was longer with RF (29 ± 15 vs. 19 ± 12 min, p < 0.02). Peak CK, CK-MB and CK-MB mass were higher, also after 24 h in the cryo group. Troponin T did not differ. Repeated transient block during application (usually with cryoablation) seemed to predict failure. Cryothermy required significantly less analgesia (p < 0.01), and no use of long sheaths (p < 0.005). The isthmus tended to be longer in the failed procedures (p = 0.117). This was similar for both groups, as was the distribution of anatomic variations. Recurrences and complaints in the successful patients were similar for both groups, with a very low recurrence of atrial flutter after initial success. Conclusions In this randomized study there was no statistical difference but a trend to less favorable outcome with 8 mm tip cryocatheters compared to RF catheters for atrial flutter ablation. Cryoablation was associated with less discomfort, fewer applications, shorter fluoroscopy times and similar procedure times. The recurrence rate was very low. Cryotherapy can be considered for atrial flutter ablation under certain circumstances especially when it has been used previously in the same patient, such as in an AF ablation. PMID:18363087

  11. Impact of Impaired Renal Function on the Incidence of Atrial Fibrillation following Radiofrequency Ablation of Cavotricuspid Isthmus-Dependent Atrial Flutter

    PubMed Central

    Kwon, Chang Hee; Kim, Min Su; Roh, Jae-Hyung; Choi, Jin Hee; Jo, Uk; Lee, Woo Seok; Kim, Yoo Ri; Nam, Gi-Byoung; Choi, Kee-Joon; Kim, You-Ho

    2015-01-01

    Background and Objectives Atrial fibrillation (AF) occurs frequently after successful radiofrequency ablation (RFA) of cavotricuspid isthmus-dependent atrial flutter (CTI-AFL). Renal impairment has been implicated in the development of AF. The purpose of this study is to clarify the impact of impaired renal function on the incidence of AF after RFA of CTI-AFL. Subjects and Methods Between January 2001 and December 2013, 240 non-dialysis patients with no prior history of AF {mean age 55.9±15.2 years old; male, 192 (80.0%)} who had undergone successful CTI-AFL ablation were included in the present study. The baseline estimated glomerular filtration rate was calculated, and patients were divided into those with impaired renal function (<60 mL/min/1.73 m2) and those with preserved renal function (≥ 60 mL/min/1.73 m2). The incidence of AF was retrospectively analyzed. Results 69 (28.8%) patients experienced new onset AF during a median follow-up duration of 26 months (inter-quartile, 7-53). The incidence of AF was significantly higher in patients with impaired renal function than in those with preserved renal function {13/25 (52.0%) versus 56/215 (26.0%), log rank p=0.019}. Age, CHADS2 score, impaired renal function, and left atrial diameter were significantly associated with the incidence of AF in univariate Cox regression analysis. Multivariate analysis showed that age was the only significant predictor of AF incidence (hazard ratio, 1.024; 95% confidence interval, 1.004-1.044, p=0.020). Conclusion Patients with impaired renal function may require careful attention for the incidence of new onset AF following successful RFA of CTI-AFL. PMID:26617649

  12. Three-dimensional electroanatomic entrainment map in atypical atrial flutter late after heart transplantation.

    PubMed

    Roten, Laurent; Tanner, Hildegard; Goy, Jean-Jacques; Delacrétaz, Etienne

    2010-02-01

    Atrial flutter in the donor part of orthotopic heart transplants has been reported and successfully treated by radiofrequency ablation of the cavotricuspid isthmus, but mapping and ablation of atypical flutter circuits may be challenging.(1) Entrainment mapping has been used in combination with activation mapping to define the mechanism of atypical atrial flutter. Here, we report a case where colour-coded three-dimensional (3D) entrainment mapping allowed us to accurately determine and visualize the 3D location of the reentrant circuit and to plan the ablation of a left atrial flutter without the need for activation mapping.

  13. Atrial flutter in myotonic dystrophy type 1: Patient characteristics and clinical outcome.

    PubMed

    Wahbi, Karim; Sebag, Frederic A; Lellouche, Nicolas; Lazarus, Arnaud; Bécane, Henri-Marc; Bassez, Guillaume; Stojkovic, Tanya; Fayssoil, Abdallah; Laforêt, Pascal; Béhin, Anthony; Meune, Christophe; Eymard, Bruno; Duboc, Denis

    2016-03-01

    The prevalence and the incidence of atrial flutter in patients with myotonic dystrophy type 1 (DM1) and the most appropriate strategies for its management are unknown. We retrospectively included in the DM1 Heart Registry 929 adult patients with DM1 admitted to our Institutions between January 2000 and September 2013. We selected patients presenting with atrial flutter and analysed data relative to the occurrence of arterial thromboembolism, severe bradyarrhythmias and atrial flutter recurrences. Atrial flutter was present in 79 of the 929 patients included in our Registry, representing a 8.5% prevalence. Patients with atrial flutter were older, had a higher muscular disability rating scale score and had higher prevalence of other cardiac manifestations of DM1. Sixty patients presented with a first episode of atrial flutter, representing a 4.6% incidence. Severe bradyarrhythmias requiring permanent pacing were present in 4 patients (6.7%). Over a 53 ± 28 months mean follow-up duration, 2 patients (3.3%) had ischaemic stroke and 12 (20%) had atrial flutter recurrences. Patients who underwent radiofrequency ablation were more frequently free of atrial flutter recurrence than other patients (95 vs. 61%; HR = 0.17; P = 0.04). Atrial flutter is a common manifestation of DM1, potentially complicated by arterial thromboembolism or severe bradyarrhythmias. Radiofrequency catheter ablation is associated with a lower risk for recurrences.

  14. Atrial flutter a manifestation of cardiac tamponade.

    PubMed

    Pabón, Guillermo Mora; Ramírez, John A

    2012-04-01

    Atrial flutter (AFL) is a common arrhythmia that is associated with postpericardiotomy and pericarditis. The relationship of AFL with tamponade has rarely been reported. A case of AFL with acute pericarditis and cardiac tamponade is thus presented here.

  15. [Double tachycardia: association of an atrial flutter and a fascicular ventricular tachycardia].

    PubMed

    Monsel, F; El Hraiech, A; Amara, W

    2013-11-01

    Double tachycardia is an uncommon type of tachycardia. We report the case of a 42-year-old patient, admitted in our department for palpitations. Two types of tachycardia, narrow and wide QRS one, have been documented in the moment of palpitations. The electrophysiology study highlights an atrial flutter and a fascicular ventricular tachycardia. The patient had no recurrence of palpitations after atrial flutter ablation and medical treatment by verapamil for his ventricular tachycardia. This is the first published case combining an atrial flutter and a ventricular tachycardia.

  16. Organized Atrial Tachycardias after Atrial Fibrillation Ablation

    PubMed Central

    Castrejón-Castrejón, Sergio; Ortega, Marta; Pérez-Silva, Armando; Doiny, David; Estrada, Alejandro; Filgueiras, David; López-Sendón, José L.; Merino, José L.

    2011-01-01

    The efficacy of catheter-based ablation techniques to treat atrial fibrillation is limited not only by recurrences of this arrhythmia but also, and not less importantly, by new-onset organized atrial tachycardias. The incidence of such tachycardias depends on the type and duration of the baseline atrial fibrillation and specially on the ablation technique which was used during the index procedure. It has been repeatedly reported that the more extensive the left atrial surface ablated, the higher the incidence of organized atrial tachycardias. The exact origin of the pathologic substrate of these trachycardias is not fully understood and may result from the interaction between preexistent regions with abnormal electrical properties and the new ones resultant from radiofrequency delivery. From a clinical point of view these atrial tachycardias tend to remit after a variable time but in some cases are responsible for significant symptoms. A precise knowledge of the most frequent types of these arrhythmias, of their mechanisms and components is necessary for a thorough electrophysiologic characterization if a new ablation procedure is required. PMID:21941669

  17. Surgical Ablation of Atrial Fibrillation.

    PubMed

    Ramlawi, Basel; Abu Saleh, Walid K

    2015-01-01

    The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions were performed using a surgical cut-and-sew approach that ensured transmurality. The Cox-Maze IV is the most currently accepted iteration. It achieves the same lesion set of the Cox- maze III but uses alternative energy sources to create the transmural lesions, potentially in a minimally invasive approach on the beating heart. High-frequency ultrasound, microwave, and laser energy have all been used with varying success in the past. Today, bipolar radiofrequency heat or cryotherapy cooling are the most accepted sources for creating linear lesions with consistent safety and transmurality. The robust and reliable nature of these energy delivery methods has yielded a success rate reaching 90% freedom from atrial fibrillation at 12 months. Such approaches offer a significant long-term advantage over catheter-based ablation, especially in patients having longstanding, persistent atrial fibrillation with characteristics such as dilated left atrial dimensions, poor ejection fraction, and failed catheter ablation. Based on these improved results, there currently is significant interest in developing a hybrid ablation strategy that incorporates the superior transmural robust lesions of surgical ablation, the reliable stroke prevention potential of epicardial left atrial appendage exclusion, and sophisticated mapping and confirmatory catheter-based ablation technology. Such a minimally invasive hybrid strategy for ablation may lead to the development of multidisciplinary "Afib teams" to

  18. Effect of Substrate Modification in Catheter Ablation of Paroxysmal Atrial Fibrillation

    PubMed Central

    Nam, Gi-Byoung; Jin, Eun-Sun; Choi, HyungOh; Song, Hae-Geun; Kim, Sung-Hwan; Kim, Ki-Hun; Hwang, Eui-Seock; Park, Kyoung-Min; Kim, Jun; Rhee, Kyoung-Suk; Choi, Kee-Joon; Kim, You-Ho

    2012-01-01

    Catheter ablation of atrial fibrillation that targets complex fractionated electrogram sites has been widely applied in the management of persistent atrial fibrillation. The clinical outcomes of pulmonary vein isolation alone and pulmonary vein isolation plus the use of complex fractionated electrogram-guided ablation (CFEA) have not been fully compared in patients with paroxysmal atrial fibrillation. This prospective study included 70 patients with symptomatic paroxysmal atrial fibrillation that remained inducible after pulmonary vein isolation. For radio-frequency catheter ablation, patients were nonrandomly assigned to a control group (pulmonary vein isolation alone, Group 1, n=35) or a CFEA group (pulmonary vein isolation plus additional CFEA, Group 2, n=35). The times to first recurrence of atrial tachyarrhythmias were compared between the 2 groups. In Group 2, CFEA rendered atrial fibrillation noninducible in 16 patients (45.7%) and converted inducible atrial fibrillation into inducible atrial flutters in 12 patients (34.3%). Atrial fibrillation remained inducible in 7 patients (20%) after the combined ablation procedures. After a mean follow-up of 23 months, freedom from recurrence of atrial tachyarrhythmias was significantly higher in Group 2 than in Group 1 (P=0.037). In Group 1, all of the recurrent tachyarrhythmias were atrial fibrillation, whereas regular tachycardia was the major mechanism of recurrent arrhythmias in Group 2 (atrial tachycardia or atrial flutter in 5 of 6 patients and atrial fibrillation in 1 patient). We found that CFEA after pulmonary vein isolation significantly reduced recurrent atrial tachyarrhythmia and might modify the pattern of arrhythmia recurrence in patients with paroxysmal atrial fibrillation. PMID:22719147

  19. Effect of years of endurance exercise on risk of atrial fibrillation and atrial flutter.

    PubMed

    Myrstad, Marius; Nystad, Wenche; Graff-Iversen, Sidsel; Thelle, Dag S; Stigum, Hein; Aarønæs, Marit; Ranhoff, Anette H

    2014-10-15

    Emerging evidence suggests that endurance exercise increases the risk for atrial fibrillation (AF) in men, but few studies have investigated the dose-response relation between exercise and risk for atrial arrhythmias. Both exposure to exercise and reference points vary among studies, and previous studies have not differentiated between AF and atrial flutter. The aim of this study was to assess the risk for atrial arrhythmias by cumulative years of regular endurance exercise in men. To cover the range from physical inactivity to long-term endurance exercise, the study sample in this retrospective cohort study was based on 2 distinct cohorts: male participants in a long-distance cross-country ski race and men from the general population, in total 3,545 men aged ≥ 53 years. Arrhythmia diagnoses were validated by electrocardiograms during review of medical records. Regular endurance exercise was self-reported by questionnaire. A broad range of confounding factors was available for adjustment. The adjusted odds ratios per 10 years of regular endurance exercise were 1.16 (95% confidence interval 1.06 to 1.29) for AF and 1.42 (95% confidence interval 1.20 to 1.69) for atrial flutter. In stratified analyses, the associations were significant in cross-country skiers and in men from the general population. In conclusion, cumulative years of regular endurance exercise were associated with a gradually increased risk for AF and atrial flutter.

  20. Repeat ablation and hospitalization following cryoballoon ablation of atrial fibrillation at a single tertiary medical center

    PubMed Central

    East, Cara; Phan, Teresa; Filardo, Giovanni; Franklin, Jay; Donsky, Alan; Wheelan, Kevin R

    2017-01-01

    Cryoablation for atrial fibrillation (AF) has rapidly become a mainstream treatment for AF. In this report, 163 patients who had undergone a cryoablation procedure at one clinical center were contacted by telephone 33.1 ± 3.3 months after the procedure. All patients had received cryoablation of the pulmonary vein ostia, although concomitant procedures were performed at the same time in over 50% of the patients, including radiofrequency and/or cryoablation of other areas of the left atrium. Freedom from a repeat ablation procedure was 87%, while freedom from recurrent hospitalization for AF was 89%, as compared to previous reports of 65%. Of the 13 patients who had a repeat ablation procedure, only one was found to have a reconnection of pulmonary veins, while 4 were found to have atrial flutter. Cryoablation for AF produces a durable result in most patients out to 3 years with better outcomes than previously reported. PMID:28127119

  1. Clinical Differences between Subtypes of Atrial Fibrillation and Flutter: Cross-Sectional Registry of 407 Patients

    PubMed Central

    Almeida, Eduardo Dytz; Guimarães, Raphael Boesche; Stephan, Laura Siga; Medeiros, Alexandre Kreling; Foltz, Katia; Santanna, Roberto Tofani; Pires, Leonardo Martins; Kruse, Marcelo Lapa; de Lima, Gustavo Glotz; Leiria, Tiago Luiz Luz

    2015-01-01

    Introduction Atrial fibrillation and atrial flutter account for one third of hospitalizations due to arrhythmias, determining great social and economic impacts. In Brazil, data on hospital care of these patients is scarce. Objective To investigate the arrhythmia subtype of atrial fibrillation and flutter patients in the emergency setting and compare the clinical profile, thromboembolic risk and anticoagulants use. Methods Cross-sectional retrospective study, with data collection from medical records of every patient treated for atrial fibrillation and flutter in the emergency department of Instituto de Cardiologia do Rio Grande do Sul during the first trimester of 2012. Results We included 407 patients (356 had atrial fibrillation and 51 had flutter). Patients with paroxysmal atrial fibrillation were in average 5 years younger than those with persistent atrial fibrillation. Compared to paroxysmal atrial fibrillation patients, those with persistent atrial fibrillation and flutter had larger atrial diameter (48.6 ± 7.2 vs. 47.2 ± 6.2 vs. 42.3 ± 6.4; p < 0.01) and lower left ventricular ejection fraction (66.8 ± 11 vs. 53.9 ± 17 vs. 57.4 ± 16; p < 0.01). The prevalence of stroke and heart failure was higher in persistent atrial fibrillation and flutter patients. Those with paroxysmal atrial fibrillation and flutter had higher prevalence of CHADS2 score of zero when compared to those with persistent atrial fibrillation (27.8% vs. 18% vs. 4.9%; p < 0.01). The prevalence of anticoagulation in patients with CHA2DS2-Vasc ≤ 2 was 40%. Conclusions The population in our registry was similar in its comorbidities and demographic profile to those of North American and European registries. Despite the high thromboembolic risk, the use of anticoagulants was low, revealing difficulties for incorporating guideline recommendations. Public health strategies should be adopted in order to improve these rates. PMID:26016782

  2. Endurance sport practice as a risk factor for atrial fibrillation and atrial flutter.

    PubMed

    Mont, Lluís; Elosua, Roberto; Brugada, Josep

    2009-01-01

    Although the benefits of regular exercise in controlling cardiovascular risk factors have been extensively proven, little is known about the long-term cardiovascular effects of regular and extreme endurance sport practice, such as jogging, cycling, rowing, swimming, etc. Recent data from a small series suggest a relationship between regular, long-term endurance sport practice and atrial fibrillation (AF) and flutter. Reported case control studies included less than 300 athletes, with mean age between 40 and 50. Most series recruited only male patients, or more than 70% males, who had been involved in intense training for many years. Endurance sport practice increases between 2 and 10 times the probability of suffering AF, after adjusting for other risk factors. The possible mechanisms explaining the association remain speculative. Atrial ectopic beats, inflammatory changes, and atrial size have been suggested. Some of the published studies found that atrial size was larger in athletes than in controls, and this was a predictor for AF. It has also been shown that the left atrium may be enlarged in as many as 20% of competitive athletes. Other proposed mechanisms are increased vagal tone and bradycardia, affecting the atrial refractory period; however, this may facilitate rather than cause the arrhythmia. In summary, recent data suggest an association between endurance sport practice and atrial fibrillation and flutter. The underlying mechanism explaining this association is unclear, although structural atrial changes (dilatation and fibrosis) are probably present. Larger longitudinal studies and mechanistic studies are needed to further characterize the association to clarify whether a threshold limit for the intensity and duration of physical activity may prevent AF, without limiting the cardiovascular benefits of exercise.

  3. Anatomic approach for ganglionic plexi ablation in patients with paroxysmal atrial fibrillation.

    PubMed

    Katritsis, Demosthenes; Giazitzoglou, Eleftherios; Sougiannis, Demetrios; Goumas, Nicolaos; Paxinos, George; Camm, A John

    2008-08-01

    There is evidence that parasympathetic denervation may prevent atrial fibrillation (AF) recurrences. This study aimed at applying an anatomic approach for ablation of atrial ganglionic plexi (GPs) in patients with paroxysmal AF. Nineteen patients with symptomatic, paroxysmal AF underwent anatomically guided radiofrequency ablation at the location of the 4 main left atrial GPs and were prospectively assessed for recurrence of AF or other atrial arrhythmia. This group was compared with 19 age- and gender-matched patients who previously underwent conventional circumferential pulmonary vein ablation. All ablation procedures were uneventful. Circumferential and GP ablations were accomplished with a radiofrequency delivery time of 28 +/- 5 versus 18 +/- 3 min (p <0.001) and a fluoroscopy time of 31 +/- 5 versus 18 +/- 5 min (p <0.001), respectively. Parasympathetic reflexes during radiofrequency ablation were elicited in 4 patients (21%). Arrhythmia recurred in 7 patients (37%) with circumferential ablation and 14 patients (74%) with GP ablation, during 1-year follow-up (p for log-rank test = 0.017). In 2 patients with GP ablation, left atrial flutters were documented in addition to AF during follow-up. Patients who underwent GP ablation had an almost 2.5 times higher risk of AF recurrence compared with those who underwent circumferential ablation (hazard ratio 2.6, 95% confidence interval 1.0 to 6.6, p = 0.038). In conclusion, anatomically guided GP ablation is feasible and safe in the electrophysiology laboratory, but this approach yields inferior clinical results compared with circumferential ablation.

  4. Radiofrequency Ablation of Persistent Atrial Fibrillation

    PubMed Central

    Hussein, Ayman A.; Saliba, Walid I.; Barakat, Amr; Bassiouny, Mohammed; Chamsi-Pasha, Mohammed; Al-Bawardy, Rasha; Hakim, Ali; Tarakji, Khaldoun; Baranowski, Bryan; Cantillon, Daniel; Dresing, Thomas; Tchou, Patrick; Martin, David O.; Varma, Niraj; Bhargava, Mandeep; Callahan, Thomas; Niebauer, Mark; Kanj, Mohamed; Chung, Mina; Natale, Andrea; Lindsay, Bruce D.; Wazni, Oussama M.

    2017-01-01

    Background Various ablation strategies of persistent atrial fibrillation (PersAF) have had disappointing outcomes, despite concerted clinical and research efforts, which could reflect progressive atrial fibrillation–related atrial remodeling. Methods and Results Two-year outcomes were assessed in 1241 consecutive patients undergoing first-time ablation of PersAF (2005–2012). The time intervals between the first diagnosis of PersAF and the ablation procedures were determined. Patients had echocardiograms and measures of B-type natriuretic peptide and C-reactive protein before the procedures. The median diagnosis-to-ablation time was 3 years (25th–75th percentiles 1–6.5). With longer diagnosis-to-ablation time (based on quartiles), there was a significant increase in recurrence rates in addition to an increase in B-type natriuretic peptide levels (P=0.01), C-reactive protein levels (P<0.0001), and left atrial size (P=0.03). The arrhythmia recurrence rates over 2 years were 33.6%, 52.6%, 57.1%, and 54.6% in the first, second, third, and fourth quartiles, respectively (Pcategorical<0.0001). In Cox Proportional Hazard analyses, B-type natriuretic peptide levels, C-reactive protein levels, and left atrial size were associated with arrhythmia recurrence. The diagnosis-to-ablation time had the strongest association with the ablation outcomes which persisted in multivariable Cox analyzes (hazard ratio for recurrence per +1Log diagnosis-to-ablation time 1.27, 95% confidence interval 1.14–1.43; P<0.0001; hazard ratio fourth versus first quartile 2.44, 95% confidence interval 1.68–3.65; Pcategorical<0.0001). Conclusions In patients with PersAF undergoing ablation, the time interval between the first diagnosis of PersAF and the catheter ablation procedure had a strong association with the ablation outcomes, such as shorter diagnosis-to-ablation times were associated with better outcomes and in direct association with markers of atrial remodeling. PMID:26763227

  5. [Characteristic electrocardiographic procedures of isthmic-dependent atrial flutter; influence of clinical and echocardiographic procedures].

    PubMed

    Milliez, P; Cosson, S; Courteaux, C; Obioha-Ngwu, O; Richardson, A; Josephson, M; Beaufils, P; Leenhardt, A

    2003-06-01

    The appearance of the F waves on the ECG is considered to be related to the type of circuit of the anti-clockwise flutters and the clockwise isthmic-dependant flutters. In the authors' experience, the usual ECG description of these two types of flutter is not always observed. This study was undertaken to analyse the different appearances of anti-clockwise and clockwise flutters and to try and explain the reasons for these differences. Over a 4 year period, 139 patients with an ECG of atrial flutter required electro-physiological studies and echocardiography of the 156 flutters analysed: 130 were anti-clockwise and 26 clockwise. Three types of anti-clockwise flutter were observed: type 1 with exclusively negative F waves in the inferior leads: type 2 and 3 with negative F waves in the inferior leads and a small (type 2) or large (type 3) positive terminal components. The types 2 and 3 were associated with a higher incidence of left atrial dilatation, cardiac disease and atrial fibrillation than type 1. Two types of clockwise flutter were observed: type 1 with positive notched F waves in the inferior leads with a return to the iso-electric line and type 2 with wide F waves in the inferior leads with two components, predominantly positive and negative, without return to the iso-electric line. There are different ECG appearances of anti-clockwise and clockwise flutter which seem to be correlated with structural cardiac abnormalities. The anti-clockwise flutters with a positive terminal component of the F waves in the inferior leads corresponds to a subgroup with a high probability of cardiac disease and left atrial dilatation.

  6. Risk of Atrial Fibrillation or Flutter Associated with Periodontitis: A Nationwide, Population-Based, Cohort Study

    PubMed Central

    Chen, Yi-Ming

    2016-01-01

    Objective To investigate the risk of atrial fibrillation or atrial flutter in patients with periodontitis (PD) in comparison with individuals without PD. Methods We used the 1999–2010 Taiwanese National Health Insurance Research Database to identify cases of PD in the year 2000 matching (1:1) with persons without PD during 1999–2000 according to sex and individual age as the control group. Using Cox proportional regression analysis adjusting for potential confounders, including age, sex, and comorbidities at baseline, and average annual number of ambulatory visits and dental scaling frequency during the follow-up period, we estimated hazard ratios (HRs) with 95% confidence intervals (CIs) to examine the risk of atrial fibrillation or flutter in PD patients in comparison with the control group. Subgroup analyses according to age, gender, or comorbidities were conducted to study the robustness of the association and investigate possible interaction effects. Results We enrolled 393,745 patients with PD and 393,745 non-PD individuals. The incidence rates of atrial fibrillation or flutter were 200 per 105 years among the PD group and 181 per 105 years in the non-PD group (incidence rate ratio, 1.10; 95% CI, 1.06–1.14). After adjusting for potential confounders, we found an increased risk of atrial fibrillation or flutter in the PD group compared with the non-PD group (HR, 1.31; 95% CI, 1.25–1.36). The greater risk of atrial fibrillation or flutter in the PD group remained significant across all disease subgroups except hyperthyroidism and sleep apnea. Conclusion The present study results indicate an increased risk of atrial fibrillation or flutter in patients with PD. Lack of individual information about alcohol consumption, obesity, and tobacco use was a major limitation. PMID:27798703

  7. Possible role for cryoballoon ablation of right atrial appendage tachycardia when conventional ablation fails.

    PubMed

    Amasyali, Basri; Kilic, Ayhan

    2015-06-01

    Focal atrial tachycardia arising from the right atrial appendage usually responds well to radiofrequency ablation; however, successful ablation in this anatomic region can be challenging. Surgical excision of the right atrial appendage has sometimes been necessary to eliminate the tachycardia and prevent or reverse the resultant cardiomyopathy. We report the case of a 48-year-old man who had right atrial appendage tachycardia resistant to multiple attempts at ablation with use of conventional radiofrequency energy guided by means of a 3-dimensional mapping system. The condition led to cardiomyopathy in 3 months. The arrhythmia was successfully ablated with use of a 28-mm cryoballoon catheter that had originally been developed for catheter ablation of paroxysmal atrial fibrillation. To our knowledge, this is the first report of cryoballoon ablation without isolation of the right atrial appendage. It might also be an alternative to epicardial ablation or surgery when refractory atrial tachycardia originates from the right atrial appendage.

  8. Pharmacological Tests in Atrial Fibrillation Ablation

    PubMed Central

    Gourraud, Jean-Baptiste; Andrade, Jason G; Macle, Laurent

    2016-01-01

    The invasive management of atrial fibrillation (AF) has been considerably changed by the identification of major sites of AF initiation and/or maintenance within the pulmonary vein antra. Percutaneous catheter ablation of these targets has become the standard of care for sustained maintenance of sinus rhythm. Long-term failure of ablation is related to an inability to create a durable transmural lesion or to identify all of the non-pulmonary vein arrhythmia triggers. Pharmacological challenges during catheter ablation have been suggested to improve outcomes in both paroxysmal and persistent AF. Herein we review the mechanism and evidence for the use of pharmacological adjuncts during the catheter ablation of AF. PMID:28116081

  9. [Atrial fibrillation ablation: application of nurse methodology].

    PubMed

    Ramos-González-Serna, Amelia; Mateos-García, M Dolores

    2011-01-01

    Ablation of pulmonary veins for treatment of atrial fibrillation involves applying radiofrequency energy wave by a catheter that causes a circumferential lesion to achieve electrical isolation and voltage drop in the interior. It is mainly applied when there is resistance to treatment and recurrence of symptoms affecting the quality of life of patients. The nurse is an important part of the multidisciplinary team who care for patients who undergo this procedure. The provision of comprehensive nursing care should include nursing procedures prior to, during, and after treatment to ensure the careful and systematic quality required. The aims of this article are: to provide specialised knowledge on the procedure of atrial fibrillation ablation, to describe the preparation of the electrophysiology laboratory, analyse nursing care and develop a standardized care plan for patients on whom this procedure is performed using the NANDA (North American Nursing Association) taxonomy and NIC (Nursing Intervention Classification).

  10. Animal studies of epicardial atrial ablation.

    PubMed

    Schuessler, Richard B; Lee, Anson M; Melby, Spencer J; Voeller, Rochus K; Gaynor, Sydney L; Sakamoto, Shun-Ichiro; Damiano, Ralph J

    2009-12-01

    The Cox maze procedure is an effective treatment of atrial fibrillation, with a long-term freedom from recurrence greater than 90%. The original procedure was highly invasive and required cardiopulmonary bypass. Modifications of the procedure that eliminate the need for cardiopulmonary bypass have been proposed, including use of alternative energy sources to replace cut-and-sew lesions with lines of ablation made from the epicardium on the beating heart. This has been challenging because atrial wall muscle thickness is extremely variable, and the muscle can be covered with an epicardial layer of fat. Moreover, the circulating intracavitary blood acts as a potential heat sink, making transmural lesions difficult to obtain. In this report, we summarize the use of nine different unidirectional devices (four radiofrequency, two microwave, two lasers, one cryothermic) for creating continuous transmural lines of ablation from the atrial epicardium in a porcine model. We define a unidirectional device as one in which all the energy is applied by a single transducer on a single heart surface. The maximum penetration of any device was 8.3 mm. All devices except one, the AtriCure Isolator pen, failed to penetrate 2 mm in some nontransmural sections. Future development of unidirectional energy sources should be directed at increasing the maximum depth and the consistency of penetration.

  11. Achieving Bidirectional Long Delays In Pulmonary Vein Antral Lines Prior To Bidirectional Block In Patients With Paroxysmal Atrial Fibrillation (The Bi-Bi Technique For Atrial Fibrillation Ablation).

    PubMed

    Mina Md Facc Fhrs, Adel F; L Warnecke Pa-C, Nicholas

    2016-01-01

    Background: Pulmonary Vein Antral isolation (PVAI) is currently the standard of care for both paroxysmal and persistent atrial fibrillation ablation. Reconnection to the pulmonary vein is the most common cause of recurrence of atrial fibrillation. Achieving the endpoint of bidirectional block (BDB) for cavotricuspid isthmus dependant flutter has improved our outcomes for atrial flutter ablation. With this we tried to achieve long delays in the pulmonary veins antral lines prior to complete isolation comparable to those delays found in patient with bidirectional block of atrial flutter lines. Study Objective:The objective of this paper was to evaluate feasibility and efficacy of achieving Bidirectional long delays in pulmonary vein antral lines prior to Bidirectional Block in patient with paroxysmal atrial fibrillation. Method: A retrospective analysis was performed on patients who had paroxysmal atrial fibrillation procedures at Unity Point Methodist from January 2015 to January 2016. 20 consecutive patients with paroxysmal atrial fibrillation who had AF ablation using the Bi-Bi technique were evaluated. Result: Mean age was 63, number of antiarrhythmic used prior to ablation was 1.4, mean left atrial size was 38 mm. Mean chads score was 1.3. Mean EF was 53%. Long delays in the left antral circumferential lines were achieved with mean delay of 142 milliseconds +/-100. Also long delays in the right antral circumferential lines were achieved with mean delay of 150 milliseconds +/-80. 95 % (19/20) of patients were free of any atrial arrhythmias and were off antiarrhythmic medications for AF post procedure. There was only one transient complication in one patient who developed a moderate pericardial effusion that was successfully drained with no hemodynamic changes. The only patient who had recurrence was found to have asymptomatic AF with burden on his device <1%, this patient was also found to have non PV triggers for his AF. In patients with only PV triggered AF

  12. Neonatal atrial flutter after insertion of an intracardiac umbilical venous catheter

    PubMed Central

    de Almeida, Marcos Moura; Tavares, Wládia Gislaynne de Sousa; Furtado, Maria Mônica Alencar Araripe; Fontenele, Maria Marcia Farias Trajano

    2016-01-01

    Abstract Objective: To describe a case of neonatal atrial flutter after the insertion of an intracardiac umbilical venous catheter, reporting the clinical presentation and reviewing the literature on this subject. Case description: A late-preterm newborn, born at 35 weeks of gestational age to a diabetic mother and large for gestational age, with respiratory distress and rule-out sepsis, required an umbilical venous access. After the insertion of the umbilical venous catheter, the patient presented with tachycardia. Chest radiography showed that the catheter was placed in the position that corresponds to the left atrium, and traction was applied. The patient persisted with tachycardia, and an electrocardiogram showed atrial flutter. As the patient was hemodynamically unstable, electric cardioversion was successfully applied. Comments: The association between atrial arrhythmias and misplaced umbilical catheters has been described in the literature, but in this case, it is noteworthy that the patient was an infant born to a diabetic mother, which consists in another risk factor for heart arrhythmias. Isolated atrial flutter is a rare tachyarrhythmia in the neonatal period and its identification is essential to establish early treatment and prevent systemic complications and even death. PMID:26525686

  13. 78 FR 11207 - Clinical Study Designs for Surgical Ablation Devices for Treatment of Atrial Fibrillation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-15

    ... Treatment of Atrial Fibrillation; Guidance for Industry and Food and Drug Administration Staff; Availability... Ablation Devices for Treatment of Atrial Fibrillation.'' This guidance provides FDA's recommendations on clinical trial designs for surgical ablation devices intended for the treatment of atrial...

  14. Effects of a novel class III antiarrhythmic agent, NIP-142, on canine atrial fibrillation and flutter.

    PubMed

    Nagasawa, Hidehiko; Fujiki, Akira; Fujikura, Naoki; Matsuda, Tomoyuki; Yamashita, Toru; Inoue, Hiroshi

    2002-02-01

    The effects of a new benzopyran derivative, NIP-142, on atrial fibrillation (AF) and flutter (AFL) and on electrophysiological variables were studied in the dog. NIP-142 (3mg/kg) was administered intravenously to pentobarbital-anesthetized beagles during vagally-induced AF and during AFL induced after placement of an intercaval crush. Isolated canine atrial tissues were studied using standard microelectrode technique. NIP-142 terminated AF in 5 of 6 dogs after an increase in fibrillation cycle length (CL) and prevented reinitiation of AF in all 6 dogs. NIP-142 terminated AFL in all 6 dogs without any appreciable change in flutter CL, and prevented reinitiation of AFL in all 6 dogs. NIP-142 prolonged atrial effective refractory periods (11+/-5%, 3+/-3%, 12+/-3%, and 10+/-5% from the baseline value at basic CLs of 150, 200, 300, and 350ms, respectively) without changes in intraatrial conduction time. The prolongation of the atrial effective refractory period was greater in the presence of vagal stimulation. NIP-142 decreased action potential phase-1 notch and increased phase-2 plateau height without making any changes in the action potential duration, although it did reverse carbachol-induced shortening of the action potential duration. In conclusion, NIP-142 is effective in treating AFL and vagally-induced AF by prolonging atrial refractoriness.

  15. Assessment of atrial electromechanical interval using echocardiography after catheter ablation in patients with persistent atrial fibrillation

    PubMed Central

    Chen, Xiaodong; Chen, Minglong; Wang, Yingying; Yang, Bing; Ju, Weizhu; Zhang, Fengxiang; Cao, Kejiang

    2016-01-01

    Abstract We sought to investigate variation of atrial electromechanical interval after catheter ablation procedure in patients with persistent atrial fibrillation using pulse Doppler (PW) and pulse tissue Doppler imaging (PW-TDI). A total of 25 consecutive in-patients with persistent atrial fibrillation, who restored sinus rhythm after ablation procedure, were recruited in our cardiac center. Echocardiography was performed on each patient at 2 hours, 1 day, 5 days, 1 month and 3 months after the ablation therapy, and atrial electromechanical delay was measured simultaneously by PW and PW-TDI. There was no significant difference between PW and TDI in measuring atrial electromechanical delay. However, at postoperative 2 hours, peak A detection rates were mathematically but nonsignificantly greater by PW-TDI than by PW. Second, there was a significant decreasing trend in atrial electromechanical interval from postoperative 2 hours to 3 months, but only postoperative 2-hour atrial electromechanical interval was significantly greater than atrial electromechanical interval at other time. Lastly, patients without postoperative 2-hour atrial electromechanical interval had a significantly longer duration of atrial fibrillation as compared to those with postoperative 2-hour atrial electromechanical interval, by the PW or by PW-TDI, respectively. In patients with persistent atrial fibrillation, atrial electromechanical interval may decrease significantly within the first 24 hours after ablation but remain consistent later, and was significantly related to patients’ duration of atrial fibrillation. Atrial electromechanical interval, as a potential predicted factor, is recommended to be measured by either PW or TDI after 24 hours, when patients had recovered sinus rhythm by radiofrequency ablation. PMID:27924066

  16. Procedural Complications, Rehospitalizations, and Repeat Procedures After Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Shah, Rashmee U.; Freeman, James V.; Shilane, David; Wang, Paul J.; Go, Alan S.; Hlatky, Mark A.

    2017-01-01

    Objectives The purpose of this study was to estimate rates and identify predictors of inpatient complications and 30-day readmissions, as well as repeat hospitalization rates for arrhythmia recurrence following atrial fibrillation (AF) ablation. Background AF is the most common clinically significant arrhythmia and is associated with increased morbidity and mortality. Radiofrequency or cryotherapy ablation of AF is a relatively new treatment option, and data on post-procedural outcomes in large general populations are limited. Methods Using data from the California State Inpatient Database, we identified all adult patients who underwent their first AF ablation from 2005 to 2008. We used multivariable logistic regression to identify predictors of complications and/or 30-day readmissions and Kaplan-Meier analyses to estimate rates of all-cause and arrhythmia readmissions. Results Among 4,156 patients who underwent an initial AF ablation, 5% had periprocedural complications, most commonly vascular, and 9% were readmitted within 30 days. Older age, female, prior AF hospitalizations, and less hospital experience with AF ablation were associated with higher adjusted risk of complications and/or 30-day readmissions. The rate of all-cause hospitalization was 38.5% by 1 year. The rate of readmission for recurrent AF, atrial flutter, and/or repeat ablation was 21.7% by 1 year and 29.6% by 2 years. Conclusions Periprocedural complications occurred in 1 of 20 patients undergoing AF ablation, and all-cause and arrhythmia-related rehospitalizations were common. Older age, female sex, prior AF hospitalizations, and recent hospital procedure experience were associated with a higher risk of complications and/or 30-day readmission after AF ablation. PMID:22222078

  17. Long-term outcome of electrical cardioversion in patients with chronic atrial flutter.

    PubMed Central

    Crijns, H. J.; Van Gelder, I. C.; Tieleman, R. G.; Brügemann, J.; De Kam, P. J.; Gosselink, A. T.; Bink-Boelkens, M. T.; Lie, K. I.

    1997-01-01

    OBJECTIVE: To determine the long-term outcome of serial electrical cardioversion therapy in patients with chronic atrial flutter. DESIGN: Prospective study, case series. SETTING: University hospital. PATIENTS: 50 consecutive patients with chronic (> 24 hours) atrial flutter without a previous relapse on antiarrhythmic drugs. INTERVENTIONS: Elective electrical cardioversion therapy, if necessary repeated, to obtain and keep patients in sinus rhythm. If the first cardioversion resulted in sinus rhythm, patients were not given antiarrhythmic drugs. Relapses were managed by repeated cardioversions then anti-arrhythmic drugs were used serially in a set sequence. MAIN OUTCOME MEASURE: Maintenance of sinus rhythm. RESULTS: Mean (SD) follow up was 3.5 (1.7) years. The first cardioversion was successful in 48 patients (96%). After a single shock and without antiarrhythmic drugs being used, 42% of the patients maintained sinus rhythm in the long-term. Only left atrial size was inversely related to the efficacy of one shock (P = 0.025). With serial cardioversion 90% of the patients were kept in sinus rhythm for 5 years. Univariate analysis showed that a long duration of arrhythmia and impaired cardiac function were both related to poor outcome. During follow up 3 patients died of progression of heart failure and another 5 died suddenly. None of these 5 patients was on antiarrhythmic drugs. CONCLUSIONS: Electrical cardioversion was an effective and safe method of converting chronic atrial flutter to sinus rhythm. To maintain sinus rhythm, more than half of the patients required multiple shocks and prophylactic antiarrhythmic drugs. Sudden death was relatively frequent in the study population; the limited data available from this study suggest that such deaths were caused by the underlying disease and not drug related proarrhythmia. PMID:9038696

  18. Surgical Ablation of Atrial Fibrillation during Mitral-Valve Surgery

    PubMed Central

    Gillinov, A. Marc; Gelijns, Annetine C.; Parides, Michael K.; DeRose, Joseph J.; Moskowitz, Alan J.; Voisine, Pierre; Ailawadi, Gorav; Bouchard, Denis; Smith, Peter K.; Mack, Michael J.; Acker, Michael A.; Mullen, John C.; Rose, Eric A.; Chang, Helena L.; Puskas, John D.; Couderc, Jean-Philippe; Gardner, Timothy J.; Varghese, Robin; Horvath, Keith A.; Bolling, Steven F.; Michler, Robert E.; Geller, Nancy L.; Ascheim, Deborah D.; Miller, Marissa A.; Bagiella, Emilia; Moquete, Ellen G.; Williams, Paula; Taddei-Peters, Wendy C.; O’Gara, Patrick T.; Blackstone, Eugene H.; Argenziano, Michael

    2015-01-01

    Background Among patients undergoing mitral-valve surgery, 30 to 50% present with atrial fibrillation, which is associated with reduced survival and increased risk of stroke. Surgical ablation of atrial fibrillation has been widely adopted, but evidence regarding its safety and effectiveness is limited. Methods We randomly assigned 260 patients with persistent or long-standing persistent atrial fibrillation who required mitral-valve surgery to undergo either surgical ablation (ablation group) or no ablation (control group) during the mitral-valve operation. Patients in the ablation group underwent further randomization to pulmonary-vein isolation or a biatrial maze procedure. All patients underwent closure of the left atrial appendage. The primary end point was freedom from atrial fibrillation at both 6 months and 12 months (as assessed by means of 3-day Holter monitoring). Results More patients in the ablation group than in the control group were free from atrial fibrillation at both 6 and 12 months (63.2% vs. 29.4%, P<0.001). There was no significant difference in the rate of freedom from atrial fibrillation between patients who underwent pulmonary-vein isolation and those who underwent the biatrial maze procedure (61.0% and 66.0%, respectively; P = 0.60). One-year mortality was 6.8% in the ablation group and 8.7% in the control group (hazard ratio with ablation, 0.76; 95% confidence interval, 0.32 to 1.84; P = 0.55). Ablation was associated with more implantations of a permanent pacemaker than was no ablation (21.5 vs. 8.1 per 100 patient-years, P = 0.01). There were no significant between-group differences in major cardiac or cerebrovascular adverse events, overall serious adverse events, or hospital readmissions. Conclusions The addition of atrial fibrillation ablation to mitral-valve surgery significantly increased the rate of freedom from atrial fibrillation at 1 year among patients with persistent or long-standing persistent atrial fibrillation, but the

  19. Management of Atrio-Esophageal Fistula Following Left Atrial Ablation

    PubMed Central

    Yousuf, Tariq; Keshmiri, Hesam; Bulwa, Zachary; Kramer, Jason; Sharjeel Arshad, Hafiz Muhammad; Issa, Rasha; Woznicka, Daniel; Gordon, Paul; Abi-Mansour, Pierre

    2016-01-01

    Currently, no guidelines have been established for the treatment of atrio-esophageal fistula (AEF) secondary to left atrial ablation therapy. After comprehensive literature review, we aim to make suggestions on the management of this complex complication and also present a case series. We performed a review of the existing literature on AEF in the setting of atrial ablation. Using keywords atrial fibrillation, atrial ablation, fistula formation, atrio-esophageal fistula, complications, interventions, and prognosis, a search was made using the medical databases PUBMED and MEDLINE for reports in English from 2000 to April 2015. A statistical analysis was performed to compare the three different intervention arms: medical management, stent placement and surgical intervention. The results of our systematic review confirm the high mortality rate associated with AEF following left atrial ablation and the necessity to diagnose atrio-esophageal injury in a timely manner. The mortality rates of this complication are 96% with medical management alone, 100% with stent placement, and 33 % with surgical intervention. Atrio-esophageal injury and subsequent AEF is an infrequent but potentially fatal complication of atrial ablation. Early, prompt, and definitive surgical intervention is the treatment of choice. PMID:28197267

  20. Steerable sheath technology in the ablation of atrial fibrillation.

    PubMed

    Joseph, Jubin; Wong, Kelvin C K; Ginks, Matthew R; Bashir, Yaver; Betts, Timothy R; Rajappan, Kim

    2013-12-01

    Steerable sheaths have been shown to reduce procedure time in the catheter ablation of atrial fibrillation (AF), where catheter positioning and stability is typically challenging. This review critically addresses and highlights the recent developments in design of sheaths used to manipulate the ablation catheter and how these developments may impact on the ablation procedure itself, in particular the likelihood of first-time success. Patents relating to steerable sheaths are reviewed and discussed to gauge potential future developments in this area.

  1. Atrial conduction delay predicts atrial fibrillation in paroxysmal supraventricular tachycardia patients after radiofrequency catheter ablation.

    PubMed

    Xu, Zhen-Xing; Zhong, Jing-Quan; Zhang, Wei; Yue, Xin; Rong, Bing; Zhu, Qing; Zheng, Zhaotong; Zhang, Yun

    2014-06-01

    This study aimed to assess whether intra- and inter-atrial conduction delay could predict atrial fibrillation (AF) for paroxysmal supraventricular tachycardia (PSVT) patients after successful treatment by radiofrequency catheter ablation (RFCA). Echocardiography examination was performed on 524 consecutive PSVT patients (15 patients were excluded). Left atrial dimension, right atrial diameter and intra- and inter-atrial conduction delay were measured before ablation. Patients were divided into group A (n = 32): occurrence of AF after the ablation and group B (n = 477): remained in sinus rhythm during follow-up. Receiver operating characteristic (ROC) curve analysis was performed to estimate the predictive value of intra- and inter-atrial conduction delay. Both intra- and inter-atrial conduction delay were higher in group A than in group B (4.79 ± 0.30 msec vs. 4.56 ± 0.32 msec; 21.98 ± 1.32 msec vs. 20.01 ± 1.33; p < 0.05). Binary logistic regression analysis showed that intra- and inter-atrial conduction were significant influential factors for the occurrence of AF (odds ratio [OR] = 13.577, 95% confidence interval [CI], 3.469-48.914; OR = 2.569, 95% CI, 1.909-3.459, p < 0.05). The ROC cure analysis revealed that intra-atrial conduction delay ≥ 4.45 msec and inter-atrial conduction delay ≥ 20.65 were the most optimal cut-off value for predicting AF in PSVT patients after RFCA. In conclusion, this is the first study to show that the intra- and inter-atrial conduction delay could effectively predict AF in post-ablation PSVT patients.

  2. Left atrium segmentation for atrial fibrillation ablation

    NASA Astrophysics Data System (ADS)

    Karim, R.; Mohiaddin, R.; Rueckert, D.

    2008-03-01

    Segmentation of the left atrium is vital for pre-operative assessment of its anatomy in radio-frequency catheter ablation (RFCA) surgery. RFCA is commonly used for treating atrial fibrillation. In this paper we present an semi-automatic approach for segmenting the left atrium and the pulmonary veins from MR angiography (MRA) data sets. We also present an automatic approach for further subdividing the segmented atrium into the atrium body and the pulmonary veins. The segmentation algorithm is based on the notion that in MRA the atrium becomes connected to surrounding structures via partial volume affected voxels and narrow vessels, the atrium can be separated if these regions are characterized and identified. The blood pool, obtained by subtracting the pre- and post-contrast scans, is first segmented using a region-growing approach. The segmented blood pool is then subdivided into disjoint subdivisions based on its Euclidean distance transform. These subdivisions are then merged automatically starting from a seed point and stopping at points where the atrium leaks into a neighbouring structure. The resulting merged subdivisions produce the segmented atrium. Measuring the size of the pulmonary vein ostium is vital for selecting the optimal Lasso catheter diameter. We present a second technique for automatically identifying the atrium body from segmented left atrium images. The separating surface between the atrium body and the pulmonary veins gives the ostia locations and can play an important role in measuring their diameters. The technique relies on evolving interfaces modelled using level sets. Results have been presented on 20 patient MRA datasets.

  3. Troponin utilization in patients presenting with atrial fibrillation/flutter to the emergency department: retrospective chart review

    PubMed Central

    2011-01-01

    Background There are few recommendations about the use of cardiac markers in the investigation and management of atrial fibrillation/flutter. Currently, it is unknown how many patients with atrial fibrillation/flutter undergo troponin testing, and how positive troponin results are managed in the emergency department. We sought to look at the emergency department troponin utilization patterns. Methods We performed a retrospective chart review of patients with atrial fibrillation/flutter presenting to the emergency department at three centers. Outcome measures included the rates of troponins ordered by emergency doctors, number of positive troponins, and those with positive troponins treated as acute coronary syndrome (ACS) by consulting services. Results Four hundred fifty-one charts were reviewed. A total of 388 (86%) of the patients had troponins ordered, 13.7% had positive results, and 4.9% were treated for ACS. Conclusions Troponin tests are ordered in a high percentage of patients with atrial fibrillation/flutter presenting to emergency departments. Five percent of our total patient cohort was diagnosed as having acute coronary syndrome by consulting services. PMID:21651774

  4. Surgical Ablation of Atrial Fibrillation Using Energy Sources.

    PubMed

    Brick, Alexandre Visconti; Braile, Domingo Marcolino

    2015-01-01

    Surgical ablation, concomitant with other operations, is an option for treatment in patients with chronic atrial fibrillation. The aim of this study is to present a literature review on surgical ablation of atrial fibrillation in patients undergoing cardiac surgery, considering energy sources and return to sinus rhythm. A comprehensive survey was performed in the literature on surgical ablation of atrial fibrillation considering energy sources, sample size, study type, outcome (early and late), and return to sinus rhythm. Analyzing studies with immediate results (n=5), the percentage of return to sinus rhythm ranged from 73% to 96%, while those with long-term results (n=20) (from 12 months on) ranged from 62% to 97.7%. In both of them, there was subsequent clinical improvement of patients who underwent ablation, regardless of the energy source used. Surgical ablation of atrial fibrillation is essential for the treatment of this arrhythmia. With current technology, it may be minimally invasive, making it mandatory to perform a procedure in an attempt to revert to sinus rhythm in patients requiring heart surgery.

  5. Surgical Ablation of Atrial Fibrillation Using Energy Sources

    PubMed Central

    Brick, Alexandre Visconti; Braile, Domingo Marcolino

    2015-01-01

    Surgical ablation, concomitant with other operations, is an option for treatment in patients with chronic atrial fibrillation. The aim of this study is to present a literature review on surgical ablation of atrial fibrillation in patients undergoing cardiac surgery, considering energy sources and return to sinus rhythm. A comprehensive survey was performed in the literature on surgical ablation of atrial fibrillation considering energy sources, sample size, study type, outcome (early and late), and return to sinus rhythm. Analyzing studies with immediate results (n=5), the percentage of return to sinus rhythm ranged from 73% to 96%, while those with long-term results (n=20) (from 12 months on) ranged from 62% to 97.7%. In both of them, there was subsequent clinical improvement of patients who underwent ablation, regardless of the energy source used. Surgical ablation of atrial fibrillation is essential for the treatment of this arrhythmia. With current technology, it may be minimally invasive, making it mandatory to perform a procedure in an attempt to revert to sinus rhythm in patients requiring heart surgery. PMID:26934404

  6. Management of refractory atrial fibrillation post surgical ablation

    PubMed Central

    Altman, Robert K.; Proietti, Riccardo; Barrett, Conor D.; Paoletti Perini, Alessandro; Santangeli, Pasquale; Danik, Stephan B.; Di Biase, Luigi

    2014-01-01

    Over the past two decades, invasive techniques to treat atrial fibrillation (AF) including catheter-based and surgical procedures have evolved along with our understanding of the pathophysiology of this arrhythmia. Surgical treatment of AF may be performed on patients undergoing cardiac surgery for other reasons (concomitant surgical ablation) or as a stand-alone procedure. Advances in technology and technique have made surgical intervention for AF more widespread. Despite improvements in outcome of both catheter-based and surgical treatment for AF, recurrence of atrial arrhythmias following initial invasive therapy may occur.Atrial arrhythmias may occur early or late in the post-operative course after surgical ablation. Early arrhythmias are generally treated with prompt electrical cardioversion with or without antiarrhythmic therapy and do not necessarily represent treatment failure. The mechanism of persistent or late occurring atrial arrhythmias is complex, and these arrhythmias may be resistant to antiarrhythmic drug therapy. The characterization and management of recurrent atrial arrhythmias following surgical ablation of AF are discussed below. PMID:24516805

  7. Mechanisms and clinical significance of early recurrences of atrial arrhythmias after catheter ablation for atrial fibrillation

    PubMed Central

    Liang, Jackson J; Dixit, Sanjay; Santangeli, Pasquale

    2016-01-01

    Early recurrence of atrial arrhythmias (ERAA) after ablation is common and strongly predicts late recurrences and ablation failure. However, since arrhythmia may eventually resolve in up to half of patients with ERAA, guidelines do not recommend immediate reintervention for ERAA episodes occurring during a 3-mo post-ablation blanking period. Certain clinical demographic, electrophysiologic, procedural, and ERAA-related characteristics may predict a higher likelihood of long-term ablation failure. In this review, we aim to discuss potential mechanisms of ERAA, and to summarize the clinical significance, prognostic implications, and treatment options for ERAA. PMID:27957250

  8. Ablating atrial fibrillation: A translational science perspective for clinicians.

    PubMed

    Weiss, James N; Qu, Zhilin; Shivkumar, Kalyanam

    2016-09-01

    Although considerable progress has been made in developing ablation approaches to cure atrial fibrillation (AF), outcomes are still suboptimal, especially for persistent and long-lasting persistent AF. In this topical review, we review the arrhythmia mechanisms, both reentrant and nonreentrant, that are potentially relevant to human AF at various stages/settings. We describe arrhythmia mapping techniques used to distinguish between the different mechanisms, with a particular focus on the detection of rotors. We discuss which arrhythmia mechanisms are likely to respond to ablation, and the challenges and prospects for improving upon current ablation strategies to achieve better outcomes.

  9. [New developments for surgical ablation of atrial fibrillation].

    PubMed

    Hemmer, W; Böhm, J O

    2007-06-01

    The Cox-Maze procedure and less complex modifications have gained widespread use as a treatment modality for patients with concomitant atrial fibrillation. Hypothermic or hyperthermic energy sources play a significant role in rapidly creating linear lesions. Endocardial ablation is easy to perform and effective with different energy sources. Epicardial techniques may simplify the procedure by allowing surgery on a beating heart. But epicardial fat and the heat sink effect of the flowing endocardial blood are obstacles to effective ablation. New devices using bipolar (irrigated) radiofrequency, microwave or laser energy, cryoablation or focused ultrasound are in clinical or pre-clinical stages and permit lesions to be created on a beating heart without cardiopulmonary bypass. Minimally invasive or video-assisted surgical techniques and effective devices for epicardial ablation will enable the treatment of patients suffering from lone atrial fibrillation. To facilitate the comparison between different techniques and devices, guidelines for reporting clinical results are necessary.

  10. Atrial Flutter

    MedlinePlus

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  11. Atrial Tachycardias after Atrial Fibrillation Ablation Manifest Different Waveform Characteristics: Implications for Characterizing Tachycardias

    PubMed Central

    Biviano, Angelo B.; Ciaccio, Edward J.; Fleitman, Jessica; Knotts, Robert; Lawrence, John; Haynes, Norrisa; Cyrille, Nicole; Hickey, Kathleen; Iyer, Vivek; Wan, Elaine; Whang, William; Garan, Hasan

    2015-01-01

    INTRODUCTON Atrial fibrillation (AF) ablation patients often manifest atrial tachycardias (AT) with atypical ECG morphologies that preclude accurate localization and mechanism. Diagnostic maneuvers used to define ATs during electrophysiology studies can be limited by tachycardia termination or transformation. Additional methods of characterizing post-AF ablation ATs are required. METHODS AND RESULTS We evaluated the utility of noninvasive ECG signal analytics in post-ablation AF patients for the following features: 1) Localization of ATs (i.e., right versus left atrium), and 2) Identification of common left AT mechanisms (i.e., focal vs. macroreentrant). Atrial waveforms from the surface ECG were used to analyze: 1) Spectral organization, including dominant amplitude (DA) and mean spectral profile (MP), and 2) Temporospatial variability, using temporospatial correlation coefficients. We studied 94 ATs in 71 patients who had undergone prior pulmonary vein isolation for AF and returned for a second ablation: 1) right atrial cavotricuspid-isthmus dependent (CTI) ATs (n=21); 2) left atrial macroreentrant ATs (n=41) and focal ATs (n=32). Right CTI ATs manifested higher DAs and lower MPs than left ATs, indicative of greater stability and less complexity in the frequency spectrum. Left macroreentrant ATs possessed higher temporospatial organization than left focal ATs. CONCLUSIONS Noninvasively recorded atrial waveform signal analyses show that right ATs possess more stable activation properties than left ATs, and left macroreentrant ATs manifest higher temporospatial organization than left focal ATs. Further prospective analyses evaluating the role these novel ECG-derived tools can play to help localize and identify mechanisms of common ATs in AF ablation patients are warranted. PMID:26228873

  12. Automated planning of ablation targets in atrial fibrillation treatment

    NASA Astrophysics Data System (ADS)

    Keustermans, Johannes; De Buck, Stijn; Heidbüchel, Hein; Suetens, Paul

    2011-03-01

    Catheter based radio-frequency ablation is used as an invasive treatment of atrial fibrillation. This procedure is often guided by the use of 3D anatomical models obtained from CT, MRI or rotational angiography. During the intervention the operator accurately guides the catheter to prespecified target ablation lines. The planning stage, however, can be time consuming and operator dependent which is suboptimal both from a cost and health perspective. Therefore, we present a novel statistical model-based algorithm for locating ablation targets from 3D rotational angiography images. Based on a training data set of 20 patients, consisting of 3D rotational angiography images with 30 manually indicated ablation points, a statistical local appearance and shape model is built. The local appearance model is based on local image descriptors to capture the intensity patterns around each ablation point. The local shape model is constructed by embedding the ablation points in an undirected graph and imposing that each ablation point only interacts with its neighbors. Identifying the ablation points on a new 3D rotational angiography image is performed by proposing a set of possible candidate locations for each ablation point, as such, converting the problem into a labeling problem. The algorithm is validated using a leave-one-out-approach on the training data set, by computing the distance between the ablation lines obtained by the algorithm and the manually identified ablation points. The distance error is equal to 3.8+/-2.9 mm. As ablation lesion size is around 5-7 mm, automated planning of ablation targets by the presented approach is sufficiently accurate.

  13. Staged hybrid ablation for persistent and longstanding persistent atrial fibrillation effectively restores sinus rhythm in long-term observation

    PubMed Central

    Filipiak, Krzysztof; Kowalski, Oskar; Buchta, Piotr; Niklewski, Tomasz; Nadziakiewicz, Pawel; Koba, Rafał; Gąsior, Mariusz; Kalarus, Zbigniew; Zembala, Marian

    2016-01-01

    Introduction Hybrid ablation (HABL) of atrial fibrillation combining endoscopic, minimally invasive, closed chest epicardial ablation with endocardial CARTO-guided accuracy was introduced to overcome the limitations of current therapeutic options for patients with persistent (PSAF) and longstanding persistent atrial fibrillation (LSPAF). The purpose of this study was to evaluate the procedural safety and feasibility as well as effectiveness of HABL in patients with PSAF and LSPAF 1 year after the procedure. Material and methods The study is a single-center, prospective clinical registry. From 07/2009 to 12.2014, 90 patients with PSAF (n = 39) and LSPAF (n = 51), at the mean age of 54.8 ±9.8, in mean EHRA class 2.6, underwent HABL. 64.4% of patients had a history of prior cardioversion or catheter ablation. Thirteen patients had LVEF less than 35%. Mean AF duration was 4.5 ±3.7 years. Patients were scheduled for 3-, 6- and 12-month follow-up with 7-day Holter monitoring. Results At 6 months after the procedure 78% (54/69) of patients were in SR. At 12 months after the procedure 86% (59/69) were in SR and 62.3% (43/69) in SR and off class I/III antiarrhythmic drugs (AADs). Only 1% (1/69) of patients required a repeat ablation for atrial flutter. A significant decrease in LA dimension and an increase in LVEF were noted. Conclusions A combination of epicardial and endocardial RF ablation should be considered as a treatment option for patients with persistent and long-standing persistent atrial fibrillation as it is safe and effective in restoring sinus rhythm. PMID:28144262

  14. Cost analysis of radiofrequency catheter ablation for atrial fibrillation.

    PubMed

    Gorenek, Bulent; Kudaiberdieva, Gulmira

    2013-09-10

    Atrial fibrillation is the most common arrhythmia associated with increased mortality and morbidity. Its management requires high healthcare expenditures; 52%-70% of expenses for AF care are constituted by hospitalization costs. The current management strategies of pharmacological rhythm control and pharmacological or invasive rate control show no difference in impact on major outcomes in patients with AF. Radiofrequency catheter ablation (RFA) has been shown to reduce the risk of AF recurrence, improve quality of life and reduce hospitalization rate as compared to pharmacological rhythm control and rate control strategies. This review summarizes current knowledge on cost and cost-effectiveness analysis of RFA for patients with atrial fibrillation.

  15. Percutaneous epicardial ablation of incessant atrial tachycardia originating from the left atrial appendage

    PubMed Central

    Ban, Ji-Eun; Park, Tae Young

    2016-01-01

    A 38-year-old woman presented with antiarrhythmic drug-refractory atrial tachycardia (AT). Holter recording demonstrated incessant episodes of AT followed by a long sinus pause. Electrophysiologic study revealed that the earliest endocardial activation was observed at the neck of the left atrial appendage (LAA). After unsuccessful endocardial ablation, epicardial access via a percutaneous subxiphoid approach demonstrated that the earliest epicardial atrial activation was observed on the opposite site to the endocardial LAA neck suggestive of ligament of Marshall (LOM) muscle sleeve as regarding the epicardial sharp potentials under guidance of a circular mapping catheter. Application of radiofrequency (RF) energy at this site terminated the tachycardia. After tachycardia ablation, the sinus pause also resolved. PMID:28066659

  16. Catheter ablation in patients with persistent atrial fibrillation

    PubMed Central

    Kirchhof, Paulus; Calkins, Hugh

    2017-01-01

    Catheter ablation is increasingly offered to patients who suffer from symptoms due to atrial fibrillation (AF), based on a growing body of evidence illustrating its efficacy compared with antiarrhythmic drug therapy. Approximately one-third of AF ablation procedures are currently performed in patients with persistent or long-standing persistent AF. Here, we review the available information to guide catheter ablation in these more chronic forms of AF. We identify the following principles: Our clinical ability to discriminate paroxysmal and persistent AF is limited. Pulmonary vein isolation is a reasonable and effective first approach for catheter ablation of persistent AF. Other ablation strategies are being developed and need to be properly evaluated in controlled, multicentre trials. Treatment of concomitant conditions promoting recurrent AF by life style interventions and medical therapy should be a routine adjunct to catheter ablation of persistent AF. Early rhythm control therapy has a biological rationale and trials evaluating its value are underway. There is a clear need to generate more evidence for the best approach to ablation of persistent AF beyond pulmonary vein isolation in the form of adequately powered controlled multi-centre trials. PMID:27389907

  17. The role of digitalis pharmacokinetics in converting atrial fibrillation and flutter to regular sinus rhythm.

    PubMed

    Jelliffe, Roger W

    2014-05-01

    This report examined the role of digitalis pharmacokinetics in helping to guide therapy with digitalis glycosides with regard to converting atrial fibrillation (AF) or flutter to regular sinus rhythm (RSR). Pharmacokinetic models of digitoxin and digoxin, containing a peripheral non-serum effect compartment, were used to analyze outcomes in a non-systematic literature review of five clinical studies, using the computed concentrations of digitoxin and digoxin in the effect compartment of these models in an analysis of their outcomes. Four cases treated by the author were similarly examined. Three literature studies showed results no different from placebo. Dosage regimens achieved ≤11 ng/g in the model's peripheral compartment. However, two other studies achieved significant conversion to RSR. Their peripheral concentrations were 9-14 ng/g. In the four patients treated by the author, three converted using classical clinical titration with incremental doses, plus therapeutic drug monitoring and pharmacokinetic guidance from the models for maintenance dosage. They converted at peripheral concentrations of 9-18 ng/g, similar to the two studies above. No toxicity was seen. Successful maintenance was achieved, using the models and their pharmacokinetic guidance, by giving somewhat larger than average recommended dosage regimens in order to maintain peripheral concentrations present at conversion. The fourth patient did not convert, but only reached peripheral concentrations of 6-7 ng/g, similar to the studies in which conversion was no better than placebo. Pharmacokinetic analysis and guidance play a highly significant role in converting AF to RSR. To the author's knowledge, this has not been specifically described before. In my experience, conversion of AF or flutter to RSR does not occur until peripheral concentrations of 9-18 ng/g are reached. Results in the four cases correlated well with the literature findings. More work is needed to further evaluate these

  18. The Role of Digitalis Pharmacokinetics in Converting Atrial Fibrillation and Flutter to Sinus Rhythm

    PubMed Central

    Jelliffe, Roger

    2014-01-01

    This report examined the role of digitalis pharmacokinetics in helping to guide therapy with digitalis glycosides with regard to converting atrial fibrillation (AF) or flutter to regular sinus rhythm (RSR). Pharmacokinetic models of digitoxin and digoxin, containing a peripheral nonserum effect compartment, were used to analyze outcomes in a nonsystematic literature review of five clinical studies, using the computed concentrations of digitoxin and digoxin in the effect compartment of these models in an analysis of their outcomes. Four cases treated by the author were similarly examined. Three literature studies showed results no different from placebo. Dosage regimens achieved ≤ 11 ng/gm in the model’s peripheral compartment. However, two other studies achieved significant conversion to RSR. Their peripheral concentrations were 9 to14 ng/gm. In addition, four patients were treated by the author. Three converted using classical clinical titration with incremental doses, plus therapeutic drug monitoring and pharmacokinetic guidance from the models for maintenance dosage. They converted at peripheral concentrations of 9 to 18 ng/gm, similar to the two studies above. No toxicity was seen. Successful maintenance was achieved, using the models and their pharmacokinetic guidance, by giving somewhat larger than average recommended dosage regimens in order to maintain peripheral concentrations present at conversion. The fourth patient did not convert, but only reached peripheral concentrations of 6–7 ng/gm, similar to the studies in which conversion was no better than placebo. Pharmacokinetic analysis and guidance play a highly significant role in converting AF to RSR. To the author’s knowledge, this has not been specifically described before. In my experience, conversion of AF or flutter to RSR does not occur until peripheral concentrations of 9 –18 ng/gm are reached. Results in the four cases correlated well with the literature findings. More work is needed to

  19. Factors influencing immediate and long-term outcome of electrical cardioversion of persistent atrial fibrillation and flutter

    PubMed Central

    Tabery, S.; Bouwels, L.; Uijen, G.J.H.; Uppelschoten, A.; Verheugt, F.W.A.

    2001-01-01

    Background To investigate which factors influence the immediate and long-term outcome of elective electrical cardioversion for persistent (>48h) atrial fibrillation or flutter. Methods In 255 patients, 435 electrical cardioversions were performed. Relevant clinical, electrocardiographic and echocardiographic factors were registered at each cardioversion. Each factor was tested separately in relation to immediate success and the outcome at six months and one year after cardioversion. Results In 70% of the patients, sinus rhythm was restored immediately after electrical cardioversion. After six months only 20% of the patients were still in sinus rhythm, and one year after cardioversion this figure had dropped to 14%. Sotalol used during electrical cardioversion resulted in the highest immediate success. Furthermore, atrial flutter, two or fewer electrical shocks and shocks ≤200 Joules resulted in the highest immediate success rate, whilst hypertensive heart disease resulted in the lowest immediate success rate. However, only shocks ≤200 Joules and a first cardioversion promoted the persistence of sinus rhythm after six months. A normal electrocardiogram, two or more cardioversions in the past and the use of a beta-blocking drug other than sotalol during cardioversion increased the chance of recurrence within six months. The duration of the arrhythmia >one month to 200 Joules and more than two cardioversions in the past were associated with a high number of recurrences one year later. With multivariate analysis we found that atrial flutter, low energy levels, low number of shocks and a long QTc-interval influence the immediate success positively. However, no factor influenced the persistence of sinus rhythm at six months and one year. Conclusion In patients with persistent atrial fibrillation or flutter, only about

  20. Predictive value of various Doppler-derived parameters of atrial conduction time for successful atrial fibrillation ablation

    PubMed Central

    Valtuille, Lucas; Choy, Jonathan B; Becher, Harald

    2015-01-01

    Various Doppler-derived parameters of left atrial electrical remodeling have been demonstrated to predict recurrence of atrial fibrillation (AF) after AF ablation. The aim of this study was to compare three Doppler-derived measures of atrial conduction time in patients undergoing AF ablation, and to investigate their predictive value for successful procedure. In 32 prospectively enrolled patients undergoing the first AF ablation, atrial conduction time was estimated by measuring the time delay between the onset of P-wave on the surface ECG to the peak of the a′-wave on the pulsed-wave Doppler and color-coded tissue Doppler imaging of the left atrial lateral wall, and to the peak of the A-wave on the pulsed-wave Doppler of the mitral inflow. There was a significant difference in the baseline atrial conduction time measured by different echocardiographic techniques. Most (88%) patients had normal or only mildly dilated left atrium. At 6 months, 12 patients (38%) had recurrent AF/atrial tachycardia. The duration of history of AF was the only predictor of AF/atrial tachycardia recurrence following the first AF ablation (P=0.024; OR 1.023, CI 1.003–1.044). A combination of normal left atrial volume and history of paroxysmal AF of ≤48 months was associated with the best outcome. Predictive value of the Doppler derived parameters of atrial conduction time may be reduced in the early stages of left atrial remodeling. Future studies may determine which echocardiographic parameter correlates best with the extent of left atrial remodeling and is most predictive of successful AF ablation. PMID:26795694

  1. [Atrial fibrillation and regular tachycardia in two young patients--are both treated with atrial fibrillation ablation?].

    PubMed

    von Bodman, G; Brömsen, J; Kopf, C; Füller, M; Block, M

    2014-04-17

    Two young patients with documented episodes of symptomatic paroxysmal atrial fibrillation have been referred for pulmonary vein isolation. Both patients had a history of concomitant regular tachycardia. in both cases pulmonaryvein isolation has not been performed but in each patient a supraventricular tachycardia (right focal atrial tachycardia/atrioventricular reentry tachycardia) could be induced and ablated instead. Concomitant supraventricular tachycardia acting as a trigger arrhythmia is frequent in young patients with atrial fibrillation without underlying cardiacdisease. In these patients a concomitant supra-ventricular tachycardia should beexcluded by electrophysiological study or ablated before pulmonary vein isolation or initiating an antiarrhythmic drug therapy. In most cases ablation of supraventricular tachycardia is safe and successful whereas the risks of ablative therapy of atrial fibrillation can not be neglected and success is moderate.

  2. Surgical ablation for atrial fibrillation: techniques, indications, and results

    PubMed Central

    Lawrance, Christopher P.; Henn, Matthew C.; Damiano, Ralph J.

    2015-01-01

    Purpose of review The aim of this review is to focus specifically on the indications, evolution of technique, and results of surgical ablation for atrial fibrillation. Recent findings With the introduction of the Cox-Maze IV procedure utilizing bipolar radiofrequency ablation and cryoablation, long-term studies have demonstrated a significant decrease in aortic cross-clamp times and major complications with a comparable rate of restoration of sinus rhythm. New hybrid approaches utilizing both catheter-based ablation and minimally invasive surgical approaches have been developed, but have not been standardized. Early studies have demonstrated reasonable success rates of hybrid procedures, with advantages that include confirmation of conduction block, decreased surgical morbidity, and possibly reduced morbidity. However, hybrid approaches have the disadvantage of significantly increased operative times. Summary The Cox-Maze IV is currently the gold standard for surgical treatment of atrial fibrillation. New hybrid approaches have potential advantages with promising early results, but a standard lesion set, improvement in operative times, and long-term results still need to be evaluated. PMID:25389650

  3. [Overview of ablation devices for atrial fibrillation surgery].

    PubMed

    Hiromoto, Atsushi; Nitta, Takashi

    2014-07-01

    Since Cox-maze procedure was first reported in 1987, ablation technology has made great progress and revolutionized atrial fibrillation surgery. Various energy sources have been introduced to facilitate creating conduction block within the atria. These sources include radiofrequency, cryothermia, microwave, laser, and high-frequency focused ultrasound( HIFU). They have been utilized both endocardially in the arrested heart and epicardially in the beating heart. The goal of all these sources is to create transmural lesions which enable irreversible conduction block. They have been reported to have clinical efficacy, but each of them have their own advantages and disadvantages, and their ability of creating transmural lesions are also different. It is important for surgeons that they fully understand these differences to make appropriate use of these technologies for achieving safe atrial fibrillation surgery and developing less invasive new procedures.

  4. A systematic review of surgical ablation versus catheter ablation for atrial fibrillation

    PubMed Central

    Kearney, Katherine; Stephenson, Rowan; Phan, Kevin; Chan, Wei Yen; Huang, Min Yin

    2014-01-01

    Background Atrial fibrillation (AF) is an increasingly prevalent condition in the ageing population, with significantly associated morbidity and mortality. Surgical and catheter ablative strategies both aim to reduce mortality and morbidity through freedom from AF. This review consolidates all currently available comparative data to evaluate these two interventions. Methods A systematic search was conducted across MEDLINE, PubMed, Embase, Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews from January 2000 until August 2013. All studies were critically appraised and only those directly comparing surgical and catheter ablation were included. Results Seven studies were deemed suitable for analysis according to the inclusion criteria. Freedom from AF was significantly higher in the surgical ablation group versus the catheter ablation group at 6-month, 12-month and study endpoint follow-up periods. Subgroup analysis demonstrated similar trends, with higher freedom from AF in the surgical ablation group for paroxysmal AF patients. The incidence of pacemaker implantation was higher, while no difference in stroke or cardiac tamponade was demonstrated for the surgical versus catheter ablation groups. Conclusions Current evidence suggests that epicardial ablative strategies are associated with higher freedom from AF, higher pacemaker implantation rates and comparable neurological complications and cardiac tamponade incidence to catheter ablative treatment. Other complications and risks were poorly reported, which warrants further randomized controlled trials (RCTs) of adequate power and follow-up duration. PMID:24516794

  5. Ablation technology for the surgical treatment of atrial fibrillation.

    PubMed

    Melby, Spencer J; Schuessler, Richard B; Damiano, Ralph J

    2013-01-01

    The Cox maze procedure for the surgical treatment of atrial fibrillation has been simplified from its original cut-and-sew technique. Various energy sources now exist which create linear lines of ablation that can be used to replace the original incisions, greatly facilitating the surgical approach. This review article describes the anatomy of the atria that must be considered in choosing a successful energy source. Furthermore the device characteristics, safety profile, mechanism of tissue injury, and ability to create transmural lesions of the various energy sources that have been used in the Cox maze procedure, along with the strengths and weaknesses of each device is discussed.

  6. Circus movement atrial flutter in the canine sterile pericarditis model. Activation patterns during initiation, termination, and sustained reentry in vivo.

    PubMed

    Schoels, W; Gough, W B; Restivo, M; el-Sherif, N

    1990-07-01

    The mechanisms of single-loop reentry in a syncytium without anatomically predetermined pathways have not been shown. Using a "jacket electrode" with 111 bipolar electrodes in a nylon matrix, we mapped in situ the atrial epicardial surface during atrial flutter in dogs with sterile pericarditis. Of 21 episodes of reentrant atrial flutter, only four showed double-loop ("figure-eight") reentry, whereas in 17 episodes a single loop was present. During initiation of single-loop reentry, an arc of functional block extended to the atrioventricular (AV) ring. This forced activation to proceed as a single wave around the free end of the arc, before breaking through the arc close to the AV ring. Activation continued as one loop around an arc close to the AV ring (in eight episodes) or around a combined functional and anatomic obstacle (in nine episodes) when the arc joined an atrial vessel. A zone of slow conduction was consistently bordered by the arc of block and the AV ring or by the anatomic obstacle and the AV ring. Spontaneous termination occurred when conduction failed in this area and the arc rejoined the AV ring. High-density recordings (2 mm) along the arc of block showed double potentials separated by an isoelectric interval, interpreted as local activation and electrotonus due to activation on the opposite side of the arc. Histologically, a diffuse inflammatory reaction involved 50-80% of the atrial wall. A transitional layer of myocardial bundles with preserved cross striation, but separated by edema and inflammatory cells, was enclosed between an epicardial layer of fragmented myocytes and an endocardial layer of grossly intact myocardium. There were no distinctive features at sites of functional conduction block or slowed conduction. In conclusion, single-loop reentry is the common pattern during atrial flutter in this model. Its induction depends on an interaction of the AV ring, a functional arc of block, and a zone of slow conduction. The location of the

  7. Analysis of Bipolar Radiofrequency Ablation in Treatment of Atrial Fibrillation Associated with Rheumatic Heart Disease

    PubMed Central

    Li, Yang; Wu, Zhong

    2016-01-01

    Background Among patients with rheumatic heart disease (RHD), 45% to 60% present with atrial fibrillation (AF), which is associated with increased rates of thromboembolism, heart failure, and even death. The bipolar radiofrequency ablation (BRFA) combining with mitral valve procedure has been adopted in patients of AF associated with RHD, but evaluations about its effectiveness are still limited. Methods A total of 87 patients with RHD and long persistent AF who had accepted mitral valve replacement concomitant with BRFA were studied. Clinical data were collected to analyze the midterm results of BRFA and evaluate its efficiency. Univariate and multivariate analyses were used to identify the independent factors associated with late AF recurrence. Results Sixty-six (75.9%) patients maintained sinus rhythm after a mean follow-up of 13.4 ± 5.2 months. Late AF recurrence had been detected in 21 (24.1%) patients, 11 (12.6%) patients were confirmed to be AF, 8 (9.2%) patients were atrial flutter and 2 (2.3%) patients were junctional rhythm. In Multivariate logistic regression analysis, body mass index (BMI) (OR = 1.756, 95% CI = 1.289–2.391, p = 0.000) and early AF recurrence (OR = 5.479, 95% CI = 1.189–25.254, p = 0.029) were independent predictors of late AF recurrence. In addition, left ventricular ejection fraction (LVEF) and New York Heart Association class showed a greater improvement in patients who maintained sinus rhythm than those who experienced late AF recurrence. Conclusion BRFA is an effective technique for the treatment of long persistent AF associated with RHD during mitral valve replacement. The BMI and early AF recurrence are independent predictors for late AF recurrence. Patients with long-term restoration of sinus rhythm experienced a greater improvement of left ventricular function after BRFA. PMID:26960188

  8. Functional mitral regurgitation: predictor for atrial substrate remodeling and poor ablation outcome in paroxysmal atrial fibrillation

    PubMed Central

    Qiao, Yu; Wu, Lingmin; Hou, Bingbo; Sun, Wei; Zheng, Lihui; Ding, Ligang; Chen, Gang; Zhang, Shu; Yao, Yan

    2016-01-01

    Abstract Functional mitral regurgitation (FMR) is not uncommon in atrial fibrillation (AF) patients. We sought to investigate the association between FMR and atrial substrate remodeling as well as the ablation outcome in paroxysmal AF (PAF) patients. We retrospectively analyzed a prospectively enrolled cohort of 132 patients (age 55.1 ± 9.6 years, 75.8% male) with symptomatic PAF who underwent initial ablation in our institute. Functional mitral regurgitation was defined as regurgitation jet area to left atrium (LA) area ratio ≥ 0.1 without any primary valvular disease. Voltage mapping of LA was performed under sinus rhythm. Low voltage zones (LVZs) were semi-quantitatively estimated and presented as low voltage index. Follow-up for AF recurrence ≥ 12 months was performed. In total, 40 patients (29.6%) were detected with FMR, who were older than the non-FMR patients (P = 0.007) and had larger LA diameters (P = 0.02). Left atrium LVZs were observed in 64.9% of patients with FMR versus 22.1% patients without FMR (P < 0.001). Functional mitral regurgitation independently predicted the presence of LVZs (OR 7.286; 95% CI 3.023–17.562; P < 0.001). During a mean follow-up of 22.9 ± 6.5 months, 38 patients (28.8%) experienced AF recurrence. The recurrence rate was 60.0% and 19.5% in FMR and non-FMR cohort, respectively (log rank P < 0.001). Multivariate analysis showed that FMR was an independent predictor for AF recurrence (HR 2.291; 95% CI 1.062–4.942; P = 0.03). Functional mitral regurgitation was strongly associated with atrial substrate remodeling. Furthermore, patients with FMR have substantial risk for AF recurrence post ablation. PMID:27472715

  9. Novel Computational Analysis of Left Atrial Anatomy Improves Prediction of Atrial Fibrillation Recurrence after Ablation.

    PubMed

    Varela, Marta; Bisbal, Felipe; Zacur, Ernesto; Berruezo, Antonio; Aslanidi, Oleg V; Mont, Lluis; Lamata, Pablo

    2017-01-01

    The left atrium (LA) can change in size and shape due to atrial fibrillation (AF)-induced remodeling. These alterations can be linked to poorer outcomes of AF ablation. In this study, we propose a novel comprehensive computational analysis of LA anatomy to identify what features of LA shape can optimally predict post-ablation AF recurrence. To this end, we construct smooth 3D geometrical models from the segmentation of the LA blood pool captured in pre-procedural MR images. We first apply this methodology to characterize the LA anatomy of 144 AF patients and build a statistical shape model that includes the most salient variations in shape across this cohort. We then perform a discriminant analysis to optimally distinguish between recurrent and non-recurrent patients. From this analysis, we propose a new shape metric called vertical asymmetry, which measures the imbalance of size along the anterior to posterior direction between the superior and inferior left atrial hemispheres. Vertical asymmetry was found, in combination with LA sphericity, to be the best predictor of post-ablation recurrence at both 12 and 24 months (area under the ROC curve: 0.71 and 0.68, respectively) outperforming other shape markers and any of their combinations. We also found that model-derived shape metrics, such as the anterior-posterior radius, were better predictors than equivalent metrics taken directly from MRI or echocardiography, suggesting that the proposed approach leads to a reduction of the impact of data artifacts and noise. This novel methodology contributes to an improved characterization of LA organ remodeling and the reported findings have the potential to improve patient selection and risk stratification for catheter ablations in AF.

  10. Novel Computational Analysis of Left Atrial Anatomy Improves Prediction of Atrial Fibrillation Recurrence after Ablation

    PubMed Central

    Varela, Marta; Bisbal, Felipe; Zacur, Ernesto; Berruezo, Antonio; Aslanidi, Oleg V.; Mont, Lluis; Lamata, Pablo

    2017-01-01

    The left atrium (LA) can change in size and shape due to atrial fibrillation (AF)-induced remodeling. These alterations can be linked to poorer outcomes of AF ablation. In this study, we propose a novel comprehensive computational analysis of LA anatomy to identify what features of LA shape can optimally predict post-ablation AF recurrence. To this end, we construct smooth 3D geometrical models from the segmentation of the LA blood pool captured in pre-procedural MR images. We first apply this methodology to characterize the LA anatomy of 144 AF patients and build a statistical shape model that includes the most salient variations in shape across this cohort. We then perform a discriminant analysis to optimally distinguish between recurrent and non-recurrent patients. From this analysis, we propose a new shape metric called vertical asymmetry, which measures the imbalance of size along the anterior to posterior direction between the superior and inferior left atrial hemispheres. Vertical asymmetry was found, in combination with LA sphericity, to be the best predictor of post-ablation recurrence at both 12 and 24 months (area under the ROC curve: 0.71 and 0.68, respectively) outperforming other shape markers and any of their combinations. We also found that model-derived shape metrics, such as the anterior-posterior radius, were better predictors than equivalent metrics taken directly from MRI or echocardiography, suggesting that the proposed approach leads to a reduction of the impact of data artifacts and noise. This novel methodology contributes to an improved characterization of LA organ remodeling and the reported findings have the potential to improve patient selection and risk stratification for catheter ablations in AF. PMID:28261103

  11. Novel P Wave Indices to Predict Atrial Fibrillation Recurrence After Radiofrequency Ablation for Paroxysmal Atrial Fibrillation

    PubMed Central

    Hu, Xiaoliang; Jiang, Jingzhou; Ma, Yuedong; Tang, Anli

    2016-01-01

    Background Circumferential pulmonary vein isolation (CPVI) is a widely used treatment for paroxysmal atrial fibrillation (AF). Several P wave duration (PWD) parameters have been suggested to predict post-ablation recurrence, but their use remains controversial. This study aimed to identify novel P wave indices that predict post-ablation AF recurrence. Material/Methods We selected 171 consecutive patients undergoing CPVI for paroxysmal AF. Electrocardiography (ECG) recordings were obtained at the beginning and the end of ablation. PWD was measured in all 12 leads. The PWD variation was calculated by subtracting the pre-ablation PWD from the post-ablation PWD. Results PWD was significantly shortened in leads II, III, aVF, and V1 after ablation. During a mean follow-up of 19.96±4.32 months, AF recurrence occurred in 32 (18.7%) patients. No significant differences in baseline characteristics or pre- or post-ablation PWD were observed between the AF recurrence and non-recurrence groups. Patients with AF recurrence exhibited a smaller PWD variation in leads II (1.21(−0.56, 2.40) vs. −5.77(−9.10, −4.06) ms, P<0.001), III (−5.92(−9.87, 3.27) vs. −9.44(−11.89, −5.57) ms, P=0.001) and V1 (−4.43(−6.64, −3.13) vs. −6.33(−8.19,−4.59) ms, P=0.003). Multivariable logistic regression analysis demonstrated that smaller PWD variations in lead II and III were independent risk factors for AF recurrence. PWD variation ≥−2.21 ms in lead II displayed the highest combined sensitivity and specificity (85.29% and 83.94%, respectively) for predicting post-ablation AF recurrence. A PWD variation ≥0 ms displayed the best practical value in predicting AF recurrence. Conclusions PWD variation in lead II is an effective predictor of post-ablation AF recurrence. PMID:27450644

  12. [Patient selection for catheter ablation of atrial fibrillation].

    PubMed

    Márquez, Manlio F

    2007-01-01

    The present report describes the program of radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) in patients referred to the AF Clinic of the National Institute of Cardiology. Specific inclusion criteria are required for RFCA of AF. If the patient fulfills it, then an electrophysiological study is performed. A transseptal approach and special mapping catheters are used to detect abnormal electrical activity (AEA). Pulmonary vein isolation is performed at the ostium/ antrum of those veins with AEA if the patient had paroxysmal AF. Global pulmonary vein isolation with some additional lines guided by electroanatomical mapping is performed in the case of chronic AF. Postoperative follow-up includes consultation, ECG and Holter monitoring at 1, 3, 6 and 12-month. RFCA is a useful and relatively safe procedure for the treatment of AF and the only one with curative potential.

  13. Towards patient-specific modelling of lesion formation during radiofrequency catheter ablation for atrial fibrillation

    PubMed Central

    Soor, Navjeevan; Morgan, Ross; Varela, Marta; Aslanidi, Oleg V.

    2017-01-01

    Radiofrequency catheter ablation procedures are a first-line method of clinical treatment for atrial fibrillation. However, they suffer from suboptimal success rates and are also prone to potentially serious adverse effects. These limitations can be at least partially attributed to the inter- and intra- patient variations in atrial wall thickness, and could be mitigated by patient-specific approaches to the procedure. In this study, a modelling approach to optimising ablation procedures in subject-specific 3D atrial geometries was applied. The approach enabled the evaluation of optimal ablation times to create lesions for a given wall thickness measured from MRI. A nonliner relationship was revealed between the thickness and catheter contact time required for fully transmural lesions. Hence, our approach based on MRI reconstruction of the atrial wall combined with subject-specific modelling of ablation can provide useful information for improving clinical procedures.

  14. Catheter ablation vs. antiarrhythmic drug treatment of persistent atrial fibrillation: a multicentre, randomized, controlled trial (SARA study)

    PubMed Central

    Mont, Lluís; Bisbal, Felipe; Hernández-Madrid, Antonio; Pérez-Castellano, Nicasio; Viñolas, Xavier; Arenal, Angel; Arribas, Fernando; Fernández-Lozano, Ignacio; Bodegas, Andrés; Cobos, Albert; Matía, Roberto; Pérez-Villacastín, Julián; Guerra, José M.; Ávila, Pablo; López-Gil, María; Castro, Victor; Arana, José Ignacio; Brugada, Josep

    2014-01-01

    Background Catheter ablation (CA) is a highly effective therapy for the treatment of paroxysmal atrial fibrillation (AF) when compared with antiarrhythmic drug therapy (ADT). No randomized studies have compared the two strategies in persistent AF. The present randomized trial aimed to compare the effectiveness of CA vs. ADT in treating persistent AF. Methods and results Patients with persistent AF were randomly assigned to CA or ADT (excluding patients with long-standing persistent AF). Primary endpoint at 12-month follow-up was defined as any episode of AF or atrial flutter lasting >24 h that occurred after a 3-month blanking period. Secondary endpoints were any atrial tachyarrhythmia lasting >30 s, hospitalization, and electrical cardioversion. In total, 146 patients were included (aged 55 ± 9 years, 77% male). The ADT group received class Ic (43.8%) or class III drugs (56.3%). In an intention-to-treat analysis, 69 of 98 patients (70.4%) in the CA group and 21 of 48 patients (43.7%) in the ADT group were free of the primary endpoint (P = 0.002), implying an absolute risk difference of 26.6% (95% CI 10.0–43.3) in favour of CA. The proportion of patients free of any recurrence (>30 s) was higher in the CA group than in the ADT group (60.2 vs. 29.2%; P < 0.001) and cardioversion was less frequent (34.7 vs. 50%, respectively; P = 0.018). Conclusion Catheter ablation is superior to medical therapy for the maintenance of sinus rhythm in patients with persistent AF at 12-month follow-up. Clinical Trial Registration Information NCT00863213 (http://clinicaltrials.gov/ct2/show/NCT00863213). PMID:24135832

  15. Atrial Electrogram Discordance During Baseline versus Re-Induced Atrial Fibrillation: Potential Ramifications For Ablation Procedures

    PubMed Central

    Biviano, Angelo B.; Ciaccio, Edward J.; Knotts, Robert; Lawrence, John; Iyer, Vivek; Whang, William; Garan, Hasan

    2015-01-01

    Background There are scant data comparing the electrogram (EGM) signal characteristics of AF in the baseline versus electrically induced states during ablation procedures. Objective The purpose of this study was to use novel intracardiac signal analysis techniques to gain insights into the effects of catheter ablation and AF re-induction on AF EGMs in patients with persistent AF. Methods We collected left atrial EGMs in patients undergoing first ablation for persistent AF at three time intervals: i) AF at baseline; ii) AF after pulmonary vein isolation (PVI) and; iii) AF after post-PVI cardioversion and subsequent re-induction. We analyzed the following two EGM spectral characteristics: 1a) dominant frequency (DF) and 1b) spectral complexity; and the following two EGM morphologic characteristics: 2a) morphology variation, and 2b) pattern repetitiveness. Results There were no differences in AF dominant frequency, dominant amplitude, spectral complexity, or metrics of EGM morphology or repetitiveness at baseline versus after PVI. However, dominant frequency, dominant amplitude, and spectral complexity differed significantly after DC cardioversion and re-induction of AF. Conclusions The frequency, spectral complexity and local EGM morphologies of AF do not significantly change over the course of a pulmonary vein isolation procedure in patients with persistent AF. However, re-induction of AF after DC cardioversion results in different DF and spectral complexity, consistent with a change in the characteristics of the perpetuating source(s) of the newly induced AF. These data suggest that AF properties can vary significantly between baseline versus re-induced AF, with potential clinical ramifications for outcomes of catheter ablation procedures. PMID:25818256

  16. Catheter ablation for atrial fibrillation: results from the first European Snapshot Survey on Procedural Routines for Atrial Fibrillation Ablation (ESS-PRAFA) Part II.

    PubMed

    Chen, Jian; Dagres, Nikolaos; Hocini, Melece; Fauchier, Laurent; Bongiorni, Maria Grazia; Defaye, Pascal; Hernandez-Madrid, Antonio; Estner, Heidi; Sciaraffia, Elena; Blomström-Lundqvist, Carina

    2015-11-01

    The European Snapshot Survey on Procedural Routines in Atrial Fibrillation Ablation (ESS-PRAFA) is a prospective, multicentre snapshot survey collecting patient-based data on current clinical practices during atrial fibrillation (AF) ablation. The participating centres were asked to prospectively enrol consecutive patients during a 6-week period (from September to October 2014). A web-based case report form was employed to collect information of patients and data of procedures. A total of 455 eligible consecutive patients from 13 countries were enrolled (mean age 59 ± 10.8 years, 28.8% women). Distinct strategies and endpoints were collected for AF ablation procedures. Pulmonary vein isolation (PVI) was performed in 96.7% and served as the endpoint in 91.3% of procedures. A total of 52 (11.5%) patients underwent ablation as first-line therapy. The cryoballoon technique was employed in 31.4% of procedures. Procedure, ablation, and fluoroscopy times differed among various types of AF ablation. Divergences in patient selection and complications were observed among low-, medium-, and high-volume centres. Adverse events were observed in 4.6% of AF ablation procedures. In conclusion, PVI was still the main strategy for AF ablation. Procedure-related complications seemed not to have declined. The centre volume played an important role in patient selection, strategy choice, and had impact on the rate of periprocedural complication.

  17. Paroxysmal atrial fibrillation ablation: Achieving permanent pulmonary vein isolation by point-by-point radiofrequency lesions

    PubMed Central

    Pedrote, Alonso; Acosta, Juan; Jáuregui-Garrido, Beatriz; Frutos-López, Manuel; Arana-Rueda, Eduardo

    2017-01-01

    Pulmonary vein isolation by point-by-point radiofrequency catheter ablation constitutes the cornerstone of catheter ablation strategies for the treatment of atrial fibrillation. However, despite advances in pulmonary vein isolation ablation strategies, long-term success rates after ablation remain suboptimal, which highlights the need to develop techniques to achieve more durable lesions. Strategies proposed to improve the durability of pulmonary vein isolation can be divided into two groups: Those addressed to improving the quality of the lesion and those that optimize the detection of acute PV reconnection during the ablation procedure. This manuscript reviews the role and potential benefits of these techniques according to current clinical evidence.

  18. Catheter Ablation in Combination With Left Atrial Appendage Closure for Atrial Fibrillation

    PubMed Central

    Swaans, Martin J.; Alipour, Arash; Rensing, Benno J.W.M.; Post, Martijn C.; Boersma, Lucas V.A.

    2013-01-01

    Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting millions of individuals worldwide 1-3. The rapid, irregular, and disordered electrical activity in the atria gives rise to palpitations, fatigue, dyspnea, chest pain and dizziness with or without syncope 4, 5. Patients with AF have a five-fold higher risk of stroke 6. Oral anticoagulation (OAC) with warfarin is commonly used for stroke prevention in patients with AF and has been shown to reduce the risk of stroke by 64% 7. Warfarin therapy has several major disadvantages, however, including bleeding, non-tolerance, interactions with other medications and foods, non-compliance and a narrow therapeutic range 8-11. These issues, together with poor appreciation of the risk-benefit ratio, unawareness of guidelines, or absence of an OAC monitoring outpatient clinic may explain why only 30-60% of patients with AF are prescribed this drug 8. The problems associated with warfarin, combined with the limited efficacy and/or serious side effects associated with other medications used for AF 12,13, highlight the need for effective non-pharmacological approaches to treatment. One such approach is catheter ablation (CA), a procedure in which a radiofrequency electrical current is applied to regions of the heart to create small ablation lesions that electrically isolate potential AF triggers 4. CA is a well-established treatment for AF symptoms 14, 15, that may also decrease the risk of stroke. Recent data showed a significant decrease in the relative risk of stroke and transient ischemic attack events among patients who underwent ablation compared with those undergoing antiarrhythmic drug therapy 16. Since the left atrial appendage (LAA) is the source of thrombi in more than 90% of patients with non-valvular atrial fibrillation 17, another approach to stroke prevention is to physically block clots from exiting the LAA. One method for occluding the LAA is via percutaneous placement of the WATCHMAN

  19. [Estimation using unipolar transesophageal recording of the interatrial conduction time in patients with paroxysmal atrial flutter and fibrillation].

    PubMed

    Simoncelli, U; Marchetti, A; Sorgato, A; Rusconi, C

    1991-06-01

    Twenty-three consecutive subjects (age 46.7 +/- 21, range 13-78) addressed to our attention for symptoms attributed to documented or suspected supra ventricular arrhythmias underwent transesophageal electrophysiologic study. On the basis of the preliminary investigations 15 proved free from organic heart disease, 2 were affected with ischemic heart disease (secondary angina), 6 with hypertensive cardiomyopathy. In each patient the sensibility, specificity and positive predictive value of the following reports regarding the occurrence of paroxysmal fibrillation and flutter (Ffap) were evaluated: a) echo reports of left atrial enlargement; b) ECG signs of atrial enlargement; c) interatrial conduction time (TCIA) assessed with unipolar transesophageal recording. As TCIA we adopted the time interval intercurrent from the first low-voltage deflection of the esophageal P wave (far field) and the apex of the intrinsecoid deflection of the same wave. TCIA proved significantly longer in the 12 patients affected with Ffap compared with those free from documented paroxysmal or inducible arrhythmias or affected with paroxysmal junctional reciprocating tachycardias: 76.6 +/- 11 vs 51.8 +/- 11.7; p less than 0.001. A TCIA greater than 63 msec characterizes with satisfactory sensibility and specificity the occurrence of Ffap: sens. 75%, spec. 91%, positive predictive value 90%. Echo and ECG reports of atrial enlargement behave as highly specific but not sufficiently sensitive indexes of the occurrence of Ffap: sens. 42%, spec. 100%, pos. pred. val. 100% and sens. 17%, spec. 100%, pos.pred.val. 100% resp. We concluded that TCIA is an index correlated with and predictive of the occurrence of Ffap in patients symptomatic for cardiopalmus or neurologic symptoms in the absence of other arrhythmias detectable with Holter monitoring which are able to produce clinical symptoms.

  20. Polymorphism rs2200733 at chromosome 4q25 is associated with atrial fibrillation recurrence after radiofrequency catheter ablation in the Chinese Han population

    PubMed Central

    Chen, Feifei; Yang, Yanzong; Zhang, Rongfeng; Zhang, Shulong; Dong, Yingxue; Yin, Xiaomeng; Chang, Dong; Yang, Zhiqiang; Wang, Kejing; Gao, Lianjun; Xia, Yunlong

    2016-01-01

    To test polymorphisms rs2200733 (chromosome 4q25) and rs2106261 (ZFHX3) were associated with AF recurrence after catheter ablation in a Chinese Han cohort. A total of 235 AF patients who underwent catheter ablation were recruited consecutively. Two polymorphisms were amplified by polymerase chain reaction and genotyped using high resolution melting analysis. Primary endpoints for AF recurrence were defined as the time to the first recurrence of atrial tachycardia/flutter/fibrillation (AT/AF). AT/AF recurrence was observed in 76 patients (35%). Allelic analysis demonstrated that rs2200733 was strongly associated with AF recurrence after ablation (P = 0.011) and the minor allele T increased the risk for recurrence (OR = 1.715). Diameters of the right atrium as well as the left and right superior pulmonary veins (PVs) were associated with rs2200733 in different genetic models (P = 0.040, 0.047 and 0.028, respectively). No significant association was detected between rs2106261 and AT/AF recurrence after ablation or atrial/PV diameters in any models. On multivariate Cox regression analysis, only rs2200733 was an independent factor of AF recurrence after ablation (HR = 0.532, P = 0.022). In Chinese Han population, rs2200733 but not rs2106261 is associated with AT/AF recurrence after ablation. The patients with genotype TT have larger size of right atrium and superior PVs than those of CC genotype. The findings suggest that rs2200733 may play a key role in regulating proper development and differentiation of atria/PVs. PMID:27158361

  1. To fumble flutter or tackle "tach"? Toward updated classifiers for atrial tachyarrhythmias.

    PubMed

    Lesh, M D; Kalman, J M

    1996-05-01

    Aristotle proposed in his short work, The Categories, that a definition is a statement of a thing's essential nature, and the essence of a thing are those of its properties that cannot change without losing its identity. But Aristotle was not faced with the flux of new information that confronts modern medicine. Nowadays, the argot of a discipline arises organically at the intersection of a given state of empiric knowledge and the exigencies of present scientific discourse. Thus, when the only treatment for a regular, narrow QRS complex tachycardia was digitalis glycosides or vasopressor infusion, the term "PAT" ("paroxysmal atrial tachycardia") seemed adequate, at least to distinguish it from ventricular tachycardia. We now prefer the term "PSVT" (paroxysmal supraventricular tachycardia) because we understand that most such tachycardias are not in truth "atrial" but involve the AV node and/or an accessory AV connection, and because we wish to report on the results of treatment specific to each of the subcategories of "PSVT." Similarly, as our knowledge of atrial arrhythmias has grown and especially as we need to describe the outcome of new interventional approaches to therapy, it may be prudent to use a nomenclature for atrial tachyarrhythmias that is based on the geometry of the tachycardia substrate, the relationship of that substrate to atrial anatomy, and the type of atrial lesions required to abolish that substrate.

  2. Wenxin Keli suppresses atrial substrate remodelling after epicardial ganglionic plexi ablation

    PubMed Central

    Xiao, Jinping; Zhao, Qingyan; Kebbati, A Hafid; Deng, Hongping; Wang, Xule; Dai, Zixuan; Yu, Shengbo; Huang, Congxin

    2013-01-01

    BACKGROUND: The chronic effects of ganglionic plexi (GP) ablation on atrial fibrillation (AF) inducibility have not been elucidated. OBJECTIVE: To investigate the effect of Wenxin Keli (WK) on the inducibility of AF and atrial substrate remodelling after epicardial GP ablation. METHODS: Twenty dogs were randomly divided into a sham-operated group, a GP ablation group and a WK-treated group. All animals underwent a left thoracotomy at the fourth intercostal space. AF inducibility was assessed by burst rapid pacing at the right atrium. Both the GP ablation group and the WK-treated group received four major GP ablations. In the WK-treated group, dogs were treated with oral WK once per day, and all animals were allowed to recover for eight weeks, after which AF inducibility and AF duration were measured again. RESULTS: After eight weeks of WK treatment, AF inducibility was lower than in the GP ablation group, and was similar to that of the sham-operated group. Compared with the sham-operated group, the levels of atrial natriuretic peptide (ANP), tumour necrosis factor-alpha (TNF-α) and interleukin (IL)-6 in right atrial tissues were increased in GP ablation group (143.6±33.7 pg/mg versus 206.2±41.4 pg/mg, P=0.02; 75.3±12.1 pg/mg versus 141.3±64 pg/mg, P=0.03; and 175.1±42.5 pg/mg versus 351.7±101 pg/mg, P<0.01, respectively). There were no significant differences in levels of ANP, TNF-α and IL-6 in atrial tissues between the sham-operated group and WK treated group. Expression of connexin 43 in atrial tissues was increased after eight weeks of GP ablation, while WK administration inhibited connexin 43 remodelling. CONCLUSIONS: Epicardial GP ablation can induce atrial substrate remodelling, including Cx43 upregulation and increased levels of ANP, TNF-α and IL-6. These changes may be suppressed by long-term oral WK administration. PMID:23940442

  3. The Effect of Aggressive Blood Pressure Control on the Recurrence of Atrial Fibrillation After Catheter Ablation: A Randomized, Open Label, Clinical Trial (Substrate Modification with Aggressive Blood Pressure Control: SMAC- AF).

    PubMed

    Parkash, Ratika; Wells, George A; Sapp, John L; Healey, Jeffrey S; Tardif, Jean-Claude; Greiss, Isabelle; Rivard, Léna; Roux, Jean-Francois; Gula, Lorne; Nault, Isabelle; Novak, Paul G; Birnie, David H; Ha, Andrew C; Wilton, Stephen B; Mangat, Iqwal; Gray, Christopher J; Gardner, Martin J; Tang, Anthony S L

    2017-02-22

    Background -Radiofrequency catheter ablation for atrial fibrillation has become an important therapy for AF, however recurrence rates remain high. We proposed to determine whether aggressive blood pressure (BP) lowering prevents recurrent atrial fibrillation (AF) after catheter ablation in patients with AF and a high symptom burden. Methods -We randomly assigned 184 patients with AF and a BP greater than 130/80 mmHg to aggressive BP (target <120/80 mm Hg) or standard BP treatment (target <140/90 mmHg) prior to their scheduled AF catheter ablation. The primary outcome was symptomatic recurrence of AF/atrial tachycardia/atrial flutter lasting greater than 30 seconds, determined 3 months beyond catheter ablation by a blinded endpoint evaluation. Results -The median follow-up was 14 months. At six months, the mean systolic BP in the aggressive BP treatment group was 123.2±13.2 versus 135.4±15.7mm Hg (p<0.001) in the standard treatment group. The primary outcome occurred in 106 patients, 54 (61.4%) in the aggressive BP treatment group, compared to 52 (61.2%) in the standard treatment group, (Hazard Ratio 0.94, 95% Confidence Interval 0.65-1.38, p=0.763). In the prespecified subgroup analysis of the influence of age, patients aged ≥ 61 years had a lower primary outcome event rate with aggressive BP (Hazard Ratio 0.58, 95% Confidence Interval (0.34, 0.97), p=0.013). There was a higher rate of hypotension requiring medication adjustment in the aggressive BP group (26% versus 0%). Conclusions -In this study, this duration of aggressive BP treatment did not reduce atrial arrhythmia recurrence after catheter ablation for AF, but resulted in more hypotension. Clinical Trial Registration -Clinicaltrials.gov Identifier: NCT00438113.

  4. Correlative anatomy for the electrophysiologist: ablation for atrial fibrillation. Part II: regional anatomy of the atria and relevance to damage of adjacent structures during AF ablation.

    PubMed

    Macedo, Paula G; Kapa, Suraj; Mears, Jennifer A; Fratianni, Amy; Asirvatham, Samuel J

    2010-07-01

    Ablation procedures for atrial fibrillation have become an established and increasingly used option for managing patients with symptomatic arrhythmia. The anatomic structures relevant to the pathogenesis of atrial fibrillation and ablation procedures are varied and include the pulmonary veins, other thoracic veins, the left atrial myocardium, and autonomic ganglia. Exact regional anatomic knowledge of these structures is essential to allow correlation with fluoroscopy and electrograms and, importantly, to avoid complications from damage of adjacent structures within the chest. We present this information as a series of 2 articles. In a prior issue, we have discussed the thoracic vein anatomy relevant to paroxysmal atrial fibrillation. In the present article, we focus on the atria themselves, the autonomic ganglia, and anatomic issues relevant for minimizing complications during atrial fibrillation ablation.

  5. Serum Galectin-3 Levels Predict Recurrences after Ablation of Atrial Fibrillation

    PubMed Central

    Clementy, Nicolas; Benhenda, Nazih; Piver, Eric; Pierre, Bertrand; Bernard, Anne; Fauchier, Laurent; Pages, Jean-Christophe; Babuty, Dominique

    2016-01-01

    Galectin-3 is a biomarker of fibrosis and atrial remodeling, involved in the mechanisms of initiation and maintenance of atrial fibrillation (AF). We sought to study the accuracy of galectin-3 level in predicting recurrences of AF after ablation. Serum concentrations of galectin-3 were determined in a consecutive series of patients addressed for AF ablation in our center. After a 3-month blanking period, recurrences of atrial arrhythmias were collected during the first year in all patients, using Holter monitoring at 3, 6 months and 12 months. A total of 160 patients were included, with a mean galectin-3 rate was 14.4 ± 5.6 ng/mL. At 12-month, 55 patients (34%) had reexperienced sustained atrial arrhythmia. Only higher galectin-3 level (HR = 1.07 [1.01–1.12], p = 0.02) and larger left atrial diameter (HR = 1.07 [1.03–1.12], p = 0.001) independently predicted recurrence. Patients with both galectin-3 level <15 ng/mL and left atrial diameter <40 millimeters had a 1-year arrhythmia-free survival rate − after a single procedure without anti-arrhythmic drug − of 91%, as compared with 41% in patients with galectin-3 ≥ 15 and left trial diameter ≥40 (p < 0.0001), whether AF was paroxysmal or persistent. Galectin-3 and left atrial diameters, rather than clinical presentation of AF, predict recurrences after ablation. PMID:27677964

  6. Optimization of Catheter Ablation of Atrial Fibrillation: Insights Gained from Clinically-Derived Computer Models

    PubMed Central

    Zhao, Jichao; Kharche, Sanjay R.; Hansen, Brian J.; Csepe, Thomas A.; Wang, Yufeng; Stiles, Martin K.; Fedorov, Vadim V.

    2015-01-01

    Atrial fibrillation (AF) is the most common heart rhythm disturbance, and its treatment is an increasing economic burden on the health care system. Despite recent intense clinical, experimental and basic research activity, the treatment of AF with current antiarrhythmic drugs and catheter/surgical therapies remains limited. Radiofrequency catheter ablation (RFCA) is widely used to treat patients with AF. Current clinical ablation strategies are largely based on atrial anatomy and/or substrate detected using different approaches, and they vary from one clinical center to another. The nature of clinical ablation leads to ambiguity regarding the optimal patient personalization of the therapy partly due to the fact that each empirical configuration of ablation lines made in a patient is irreversible during one ablation procedure. To investigate optimized ablation lesion line sets, in silico experimentation is an ideal solution. 3D computer models give us a unique advantage to plan and assess the effectiveness of different ablation strategies before and during RFCA. Reliability of in silico assessment is ensured by inclusion of accurate 3D atrial geometry, realistic fiber orientation, accurate fibrosis distribution and cellular kinetics; however, most of this detailed information in the current computer models is extrapolated from animal models and not from the human heart. The predictive power of computer models will increase as they are validated with human experimental and clinical data. To make the most from a computer model, one needs to develop 3D computer models based on the same functionally and structurally mapped intact human atria with high spatial resolution. The purpose of this review paper is to summarize recent developments in clinically-derived computer models and the clinical insights they provide for catheter ablation. PMID:25984605

  7. Epicardial Atrial Ablation Using a Novel Articulated Robotic Medical Probe Via a Percutaneous Subxiphoid Approach.

    PubMed

    Ota, Takeyoshi; Degani, Amir; Zubiate, Brett; Wolf, Alon; Choset, Howie; Schwartzman, David; Zenati, Marco A

    2006-01-01

    OBJECTIVE: Minimally invasive epicardial atrial ablation to cure atrial fibrillation through the use of a percutaneous subxiphoid approach currently has a lack of dedicated technology for intrapericardial navigation around the beating heart. We have developed a novel articulated robotic medical probe and performed preliminary experiments in a porcine preparation. METHODS: In five large, healthy pigs, the teleoperated robotic system was introduced inside the pericardial space through a percutaneous subxiphoid approach. Secondary visualization of the left atrium and left atrial appendage was achieved with the use of a 5-mm scope inserted through a left thoracic port. The operator actively controlled the path of the robot by using a master manipulator. The catheter, with an irrigated radiofrequency tip, was guided through the working port of the robot to achieve epicardial ablation of the left atrium. RESULTS: Access to the pericardial space and progression around the left atrium was successful in all cases, with no interference with the beating heart such as a fatal arrhythmia, unexpected bleeding, and hypotension. Epicardial ablation was successfully performed in all five cases. No adverse hemodynamic or electrophysiological events were noted during the trials. When the animals were killed, there was no visually detected injury on the surrounding mediastinal structures caused by ablation. Transmural ablation was confirmed by histopathology of the left atrium. CONCLUSIONS: We have developed a dedicated articulated robotic medical probe and successfully performed epicardial left atrial radiofrequency ablation. Based on the feedback from these preliminary experiments, the radius of curvature and proper visualization of the device are being improved in the next generation prototype.

  8. Volume Matters: Improved Outcomes for Patients Presenting to High-Volume Emergency Departments with Atrial Flutter and Fibrillation

    PubMed Central

    Graham, Michelle M.; Holroyd, Brian R.

    2016-01-01

    Objectives Clinical familiarity plays a role in health outcomes; the relationship between emergency department (ED) volume and outcomes for atrial fibrillation and flutter (AFF) are not clear. We compared ED presentation outcomes for AFF between high (HV) and low volume (LV) EDs in Alberta, Canada. Methods 45,372 AFF presentations for patients aged ≥ 35 years from all 104 EDs in Alberta during 1999 to 2011 using administrative health databases formed a retrospective cohort. EDs were grouped by annual AFF volume: 11 high (>100 presentations) or 93 low (≤100 presentations). Outcomes included hospital admission rate, return to ED for AFF within 30 and 90 days, and death within 30 and 90 days. Analyses included statistical tests and mixed effects modeling. Results Mean age at ED presentation was 69.8 years (52% male). HV ED presentations were associated with lower admissions (adjusted odds ratio [aOR] = 0.68, 95% confidence interval [CI] 0.64, 0.72; p-value [p]<0.001), ED returns at 90 (aOR = 0.81, 95% CI 0.73, 0.90; p<0.001) days, and a higher likelihood of specialist visits at 30 (aOR = 1.81, 95% CI 1.68, 1.94; p<0.001) and 90 (aOR = 1.82, 95% CI 1.76, 2.03; p<0.001) days. For admitted patients, there were fewer returns to HV EDs at 30 (aOR = 0.37, 95% CI 0.15, 0.87; p = 0.02) and 90 (aOR = 0.48, 95% CI 0.26, 0.89; p = 0.02) days after hospital discharge. There was no difference in death between the two groups. Conclusions AFF patients presenting to HV EDs experienced fewer admissions and AFF ED revisit and higher specialist referrals compared to LV EDs. PMID:27814387

  9. The effects of fat layer on temperature distribution during microwave atrial fibrillation catheter ablation.

    PubMed

    Zhai, Fei; Nan, Qun; Guo, Xuemei

    2016-01-01

    To investigate the effects of fat layer on the temperature distribution during microwave atrial fibrillation catheter ablation in the conditions of different ablation time; 3D finite element models (fat layer and no fat layer) were built, and temperature distribution was obtained based on coupled electromagnetic-thermal analysis at 2.45 GHz and 30 W of microwave power. Results shown: in the endocardial ablation, the existence of the fat layer did not affect the shape of the 50 °C contour before 30 s. The increase speed of depth became quite slowly in the model with fat layer after 30 s. When ablation depth needed fixed, there are no significant effect on effectively ablation depth whether fat layer over or not. However, the existence of fat layer makes the temperature lower in the myocardium, and maximum temperature point closer to the myocardium surface. What is more, in the model with fat layer, effective ablation reach lower maximum temperature and the shallower depth of 50 °C contour. But there are larger ablation axial length and transverse width. In this case, doctor should ensure safety of normal cardiac tissue around the target tissue. In the epicardial ablation, the existence of fat layer seriously affects result of the microwave ablation. The epicardial ablation needs more heating time to create lesion. But epicardial ablation can be better controlled in the shape of effective ablation area because of the slowly increase of target variables after the appearing of 50 °C contour. Doctor can choose endocardial or epicardial ablation in different case of clinic requirement.

  10. Outcomes of Cryoballoon Ablation in High- and Low-Volume Atrial Fibrillation Ablation Centres: A Russian Pilot Survey

    PubMed Central

    Mikhaylov, Evgeny N.; Lebedev, Dmitry S.; Pokushalov, Evgeny A.; Davtyan, Karapet V.; Ivanitskii, Eduard A.; Nechepurenko, Anatoly A.; Kosonogov, Alexey Ya.; Kolunin, Grigory V.; Morozov, Igor A.; Termosesov, Sergey A.; Maykov, Evgeny B.; Khomutinin, Dmitry N.; Eremin, Sergey A.; Mayorov, Igor M.; Romanov, Alexander B.; Shabanov, Vitaliy V.; Shatakhtsyan, Victoria; Tsivkovskii, Viktor; Revishvili, Amiran Sh.; Shlyakhto, Evgeny V.

    2015-01-01

    Purpose. The results of cryoballoon ablation (CBA) procedure have been mainly derived from studies conducted in experienced atrial fibrillation (AF) ablation centres. Here, we report on CBA efficacy and complications resulting from real practice of this procedure at both high- and low-volume centres. Methods. Among 62 Russian centres performing AF ablation, 15 (24%) used CBA technology for pulmonary vein isolation. The centres were asked to provide a detailed description of all CBA procedures performed and complications, if encountered. Results. Thirteen sites completed interviews on all CBAs in their centres (>95% of CBAs in Russia). Six sites were high-volume AF ablation (>100 AF cases/year) centres, and 7 were low-volume AF ablation. There was no statistical difference in arrhythmia-free rates between high- and low-volume centres (64.6 versus 60.8% at 6 months). Major complications developed in 1.5% of patients and were equally distributed between high- and low-volume centres. Minor procedure-related events were encountered in 8% of patients and were more prevalent in high-volume centres. Total event and vascular access site event rates were higher in women than in men. Conclusions. CBA has an acceptable efficacy profile in real practice. In less experienced AF ablation centres, the major complication rate is equal to that in high-volume centres. PMID:26640789

  11. Patient-specific left atrial wall-thickness measurement and visualization for radiofrequency ablation

    NASA Astrophysics Data System (ADS)

    Inoue, Jiro; Skanes, Allan C.; White, James A.; Rajchl, Martin; Drangova, Maria

    2014-03-01

    INTRODUCTION: For radiofrequency (RF) catheter ablation of the left atrium, safe and effective dosing of RF energy requires transmural left atrium ablation without injury to extra-cardiac structures. The thickness of the left atrial wall may be a key parameter in determining the appropriate amount of energy to deliver. While left atrial wall-thickness is known to exhibit inter- and intra-patient variation, this is not taken into account in the current clinical workflow. Our goal is to develop a tool for presenting patient-specific left atrial thickness information to the clinician in order to assist in the determination of the proper RF energy dose. METHODS: We use an interactive segmentation method with manual correction to segment the left atrial blood pool and heart wall from contrast-enhanced cardiac CT images. We then create a mesh from the segmented blood pool and determine the wall thickness, on a per-vertex basis, orthogonal to the mesh surface. The thickness measurement is visualized by assigning colors to the vertices of the blood pool mesh. We applied our method to 5 contrast-enhanced cardiac CT images. RESULTS: Left atrial wall-thickness measurements were generally consistent with published thickness ranges. Variations were found to exist between patients, and between regions within each patient. CONCLUSION: It is possible to visually determine areas of thick vs. thin heart wall with high resolution in a patient-specific manner.

  12. Antiarrhythmic Effect Of Antioxidants In Patients With Atrial Fibrillation.

    PubMed

    Khabchabov PhD, Rustam; Rg PhD, Khabchabov; Er PhD, Makhmudova

    2016-01-01

    Resume In accordance with modern concepts, one of the leading roles in the development of paroxysmal atrial fibrillation and flutter, belongs - the restructuring of the myocardium, in second place - sick sinus syndrome and in third place - the presence of accessory pathways and hormonal disorders. The development of atrial fibrillation and flutter in the structural pathology, primarily begins with of drugs if it does not work, we have to carry out ablation. Providing proper, effective and important combination therapy - is the main challenge in cardiology.

  13. Chronic Atrial Fibrillation Ablation with Harmonic Scalpel during Mitral Valve Surgery

    PubMed Central

    Brick, Alexandre Visconti; Braile, Domingo M.

    2017-01-01

    Objective To evaluate surgical treatment of chronic atrial fibrillation with ultrasound in patients with mitral valve disease, considering preoperative clinical characteristics of patients undergoing surgical procedure and follow-up in the immediate postoperative period, in hospital and up to 60 months after discharge. Methods We studied 100 patients with chronic atrial fibrillation and mitral valve disease who underwent surgical treatment using ultrasound ablation. Patient data were reviewed by consulting the control reports, including signs and symptoms, underlying disease, functional class, hospital stay, surgical procedure time, ablation time, immediate complications, and complications at discharged and up to 60 months later. Actuarial curve (Kaplan-Meier) was used for the study of permanence without recurrence after 12, 24, 36, 48 and 60 months. Results 86% of the patients had rheumatic mitral valve disease, 14% had degeneration of the mitral valve, 40% had mitral regurgitation, and 36% had mitral stenosis. Main symptoms included palpitations related to tachycardia by chronic atrial fibrillation (70%), congestive heart failure (70%), and previous episodes of acute pulmonary edema (27%). Early results showed that 94% of the patients undergoing ultrasound ablation reversed the rate of chronic atrial fibrillation, 86% being in sinus rhythm and 8% in atrioventricular block. At hospital discharge, maintenance of sinus rhythm was observed in 86% of patients and there was recurrence of chronic atrial fibrillation in 8% of patients. At follow-up after 60 months, 83.8% of patients maintained the sinus rhythm. Conclusion Surgical treatment of chronic atrial fibrillation with ultrasound concomitant with mitral valve surgery is feasible and satisfactory, with maintenance of sinus rhythm in most patients (83.8%) after 60 months of follow-up.

  14. [Does radiofrequency ablation of the bundle of Kent results in a lower risk of atrial fibrillation?].

    PubMed

    Brembilla-Perrot, B; Beurrier, D; Houriez, P

    2002-02-01

    Radiofrequency ablation of the Bundle of Kent is a common method of treating malignant forms of the Wolff-Parkinson-White syndrome and the paroxysmal junctional tachycardia which may complicate this condition. The aim of this study was to investigate the effects of ablation of a latent or patent Bundle of Kent on the prevention of atrial fibrillation. One hundred and thirty eight patients aged 15 to 81 years of age with one or more patent (Group I) (n = 96) or latent Bundles of Kent (Group II) (n = 42) underwent successful ablation of the Bundle of Kent. Five patients in Group I (5%) and 4 in Group II (9.5%) had spontaneous paroxysmal atrial fibrillation before ablation. During electrophysiological investigation, AF was induced in 7 patients, 2 of whom had spontaneous AF in Group I and 3 in Group II. During follow-up (3 +/- 1 years), 3 patients of Group I went on to develop AF: 2 of them had never had the arrhythmia before: 4 patients of Group II, including 2 with previous AF, went on to develop AF. The risk of spontaneous AF was correlated to older ages. The authors conclude that persistence of the risk of spontaneous AF after ablation of a Bundle of Kent should be investigated especially in patients over 45 years of age.

  15. Ablation for atrial fibrillation during mitral valve surgery: 1-year results through continuous subcutaneous monitoring.

    PubMed

    Bogachev-Prokophiev, Alexandr; Zheleznev, Sergey; Romanov, Alexander; Pokushalov, Evgeny; Pivkin, Alexey; Corbucci, Giorgio; Karaskov, Alexander

    2012-07-01

    Continuous monitoring of cardiac rhythm may play an important role in measuring the true symptomatic/asymptomatic atrial fibrillation (AF) burden and improve the management of anti-arrhythmic and anti-thrombotic therapies. Forty-seven patients with mitral valve disease and longstanding persistent AF (LSPAF) underwent a left atrial maze procedure with bipolar radiofrequency and valve surgery. The follow-up data recorded by an implanted loop recorder were analysed after 3, 6 and 12 months. On discharge, 40 (85.1%) patients were in stable sinus rhythm, as documented by in-office electrocardiography (ECG), 4 (8.5%) were in pacemaker rhythm and 3 (6.4%) were in AF. One (2.1%) patient died after 7 months. On 12-month follow-up examination, 30 (65.2%) patients had an AF burden <0.5% and were classified as responders. Three (6.5%) of the 16 non-responders had atrial flutter and 13 (27.7%) had documented AF recurrences with an AF burden >0.5%. Two (4.3%) patients with AF recurrences were completely asymptomatic. Among the symptomatic events stored by the patients, only 27.6% was confirmed as genuine AF recurrences according to the concomitant ECG recorded by the implanted loop recorder. A concomitant bipolar maze procedure during mitral valve surgery is effective in treating AF, as proved by detailed 1-year continuous monitoring.

  16. Ablation for atrial fibrillation during mitral valve surgery: 1-year results through continuous subcutaneous monitoring†

    PubMed Central

    Bogachev-Prokophiev, Alexandr; Zheleznev, Sergey; Romanov, Alexander; Pokushalov, Evgeny; Pivkin, Alexey; Corbucci, Giorgio; Karaskov, Alexander

    2012-01-01

    Continuous monitoring of cardiac rhythm may play an important role in measuring the true symptomatic/asymptomatic atrial fibrillation (AF) burden and improve the management of anti-arrhythmic and anti-thrombotic therapies. Forty-seven patients with mitral valve disease and longstanding persistent AF (LSPAF) underwent a left atrial maze procedure with bipolar radiofrequency and valve surgery. The follow-up data recorded by an implanted loop recorder were analysed after 3, 6 and 12 months. On discharge, 40 (85.1%) patients were in stable sinus rhythm, as documented by in-office electrocardiography (ECG), 4 (8.5%) were in pacemaker rhythm and 3 (6.4%) were in AF. One (2.1%) patient died after 7 months. On 12-month follow-up examination, 30 (65.2%) patients had an AF burden <0.5% and were classified as responders. Three (6.5%) of the 16 non-responders had atrial flutter and 13 (27.7%) had documented AF recurrences with an AF burden >0.5%. Two (4.3%) patients with AF recurrences were completely asymptomatic. Among the symptomatic events stored by the patients, only 27.6% was confirmed as genuine AF recurrences according to the concomitant ECG recorded by the implanted loop recorder. A concomitant bipolar maze procedure during mitral valve surgery is effective in treating AF, as proved by detailed 1-year continuous monitoring. PMID:22514258

  17. Pheochromocytoma diagnosed after anticoagulation for atrial fibrillation ablation procedure: a giant in disguise.

    PubMed

    Galvão Braga, Carlos; Ribeiro, Sílvia; Martins, Juliana; Arantes, Carina; Ramos, Vítor; Primo, João; Magalhães, Sónia; Correia, Adelino

    2014-04-01

    Pheochromocytoma is a rare catecholamine-producing tumor, discovered incidentally in 50% of cases. We present the case of a 44-year-old male with a history of paroxysmal palpitations. Baseline ECG, transthoracic echocardiogram and ECG stress test showed no relevant alterations. Paroxysmal atrial fibrillation was detected on 24-hour Holter ECG. After antiarrhythmic therapy, the patient remained symptomatic, and was accordingly referred for electrophysiological study and atrial fibrillation ablation. Anticoagulation was initiated before the procedure. After ablation and still anticoagulated, he complained of hematospermia. The abdominal and pelvic imaging study showed a 10-cm left adrenal mass, predominantly cystic, compatible with pheochromocytoma, which was confirmed after biochemical tests (increased urine metanephrines and plasma catecholamines). Metaiodobenzylguanidine scintigraphy scanning confirmed localized disease in the adrenal gland, excluding other uptake foci. Following appropriate preoperative management, surgical resection of the giant mass was performed successfully and without complications.

  18. Stroke prevention following modified endoscopic ablation and appendectomy for atrial fibrillation.

    PubMed

    Ma, Nan; Jiang, Zhaolei; Chen, Fei; Yin, Hang; Ding, Fangbao; Mei, Ju

    2016-09-01

    We reported the results of stroke prevention following modified endoscopic procedure for atrial fibrillation. 82 patients underwent modified endoscopic procedure for atrial fibrillation (AF), in whom 47 had paroxysmal, 28 had persistent, and 7 had long-standing atrial fibrillation. CHA2DS2VASC median score was 3 (range from 0 to 8). The procedure was performed on the beating heart, through 3 ports on the left chest wall. Pulmonary vein isolation and ablation of the left atrium were achieved by bipolar radiofrequency ablation. Left atrial appendage (LAA) was excluded by stapler. Brain CT, cardiac CT and 24-h Holter monitoring were performed following the procedure. The procedure was successfully completed for all patients. The mean duration was 122 ± 40.1 min. LAA was excluded after appendectomy and checked by intraoperative transesophageal echocardiography. The mean follow-up duration was 24.3 ± 3.5 months. No patients showed signs and symptoms of transient ischemic attack or stroke. No new positive findings were demonstrated by recurring brain CT scan performed after the procedure. Cardiac CT confirmed the absence of LAA and thrombosis in the left atrium. 87.8 % (72/82) of all patients were in sinus rhythm. Our results demonstrate that the modified endoscopic procedure is a safe, effective, and appropriate treatment for AF, which restores sinus rhythm and may be associated with the prevention of AF-related stroke.

  19. Efficacy of circumferential pulmonary vein ablation of atrial fibrillation in endurance athletes

    PubMed Central

    Calvo, Naiara; Mont, Lluís; Tamborero, David; Berruezo, Antonio; Viola, Graziana; Guasch, Eduard; Nadal, Mercè; Andreu, David; Vidal, Barbara; Sitges, Marta; Brugada, Josep

    2010-01-01

    Aims Long-term endurance sport practice has been increasingly recognized as a risk factor for lone atrial fibrillation (AF). However, data on the outcome of circumferential pulmonary vein ablation (CPVA) in endurance athletes are scarce. The aim of the study was to evaluate the efficacy of CPVA in AF secondary to endurance sport practice. Methods and results Patients submitted to CPVA answered a questionnaire about lifetime history of endurance sport practice. Endurance athletes were defined as those who engaged in >3 h per week of high-intensity exercise for at least the 10 years immediately preceding their AF diagnosis. A series of 182 consecutive patients was included (51 ± 11 years, 65% with paroxysmal AF, 81% men, 42 ± 6 mm mean left atrial diameter); 107 (59%) patients had lone AF, and 42 of them (23% of the study population) were classified as endurance athletes (lone AF sport group). Freedom from arrhythmia after a single CPVA was similar in the lone AF sport group compared with the remaining patients (P = 0.446). Left atrial size and long-standing AF were the only independent predictors for arrhythmia recurrence after ablation. Conclusion Circumferential pulmonary vein ablation was as effective in AF secondary to endurance sport practice as in other aetiologies of AF. PMID:19923171

  20. Remotely controlled steerable sheath improves result and procedural parameters of atrial fibrillation ablation with magnetic navigation

    PubMed Central

    Errahmouni, Abdelkarim; Latcu, Decebal Gabriel; Bun, Sok-Sithikun; Rijo, Nicolas; Dugourd, Céline; Saoudi, Nadir

    2015-01-01

    Aims The magnetic navigation (MN) system may be coupled with a new advancement system that fully controls both the catheter and a robotic deflectable sheath (RSh) or with a fixed-curve sheath and a catheter-only advancement system (CAS). We aimed to compare these approaches for atrial fibrillation (AF) ablation. Methods and results Atrial fibrillation ablation patients (45, 23 paroxysmal and 22 persistent) performed with MN–RSh (RSh group) were compared with a control group (37, 18 paroxysmal and19 persistent) performed with MN–CAS (CAS group). Setup duration was measured from the procedure's start to operator transfer to control room. Ablation step duration was defined as the time from the beginning of the first radiofrequency (RF) pulse to the end of the last one and was separately acquired for the left and the right pulmonary vein (PV) pairs. Clinical characteristics, left atrial size, and AF-type distribution were similar between the groups. Setup duration as well as mapping times was also similar. Ablation step duration for the left PVs was similar, but was shorter for the right PVs in RSh group (46 ± 9 vs. 63 ± 12 min, P < 0.0001). Radiofrequency delivery time (34 ± 9 vs. 40 ± 11 min, P = 0.007) and procedure duration (227 ± 36 vs. 254 ± 62 min, P = 0.01) were shorter in RSh group. No complication occurred in RSh group. During follow-up, there were five recurrences (11%) in RSh group and 11 (29%) in CAS group (P = 0.027). Conclusion The use of the RSh for AF ablation with MN is safe and improves outcome. Right PV isolation is faster, RF delivery time and procedure time are reduced. PMID:25662989

  1. Association of Single Nucleotide Polymorphisms with Atrial Fibrillation and the Outcome after Catheter Ablation

    PubMed Central

    Hu, Yu-Feng; Wang, Hsueh-Hsiao; Yeh, Hung-I; Lee, Kun-Tai; Lin, Yenn-Jiang; Chang, Shih-Lin; Lo, Li-Wei; Tuan, Ta-Chuan; Li, Cheng-Hung; Chao, Tze-Fan; Chung, Fa-Po; Liao, Jo-Nan; Tang, Paul Wei Hua; Tsai, Wei-Chung; Chiou, Chuen-Wang; Chen, Shih-Ann

    2016-01-01

    Background The association of gene variants with atrial fibrillation (AF) type and the recurrence of AF after catheter ablation in Taiwan is still unclear. In this study, we aimed to investigate the relationships between gene variants, AF type, and the recurrence of AF. Methods In our investigation, we examined 383 consecutive patients with AF (61.9 ± 14.0 years; 63% men); of these 383 patients, 189 underwent catheter ablation for drug-refractory AF. Thereafter, the single nucleotide polymorphisms rs2200733, and rs7193343 were genotyped using real-time polymerase chain reaction. Results The rs7193343 variant was independently associated with non-paroxysmal AF (non-PAF). In the PAF group, the rs7193343 variant was independently associated with AF recurrence after catheter ablation. However, the rs2200733 variant was not associated with AF recurrence in this group. The combination of the rs7193343 and rs2200733 risk alleles was associated with a better predictive power in the PAF patients. In contrast, in the non-PAF group, the SNPs were not associated with recurrence. The rs7193343 and rs2200733 variants were not associated with different atrial voltage and activation times. Conclusions The rs7193343 variants were associated with AF recurrence after catheter ablation in PAF patients but not in non-PAF patients. The rs7193343 CC variant was independently associated with non-PAF. PMID:27713600

  2. Atrial Substrate Modification in Atrial Fibrillation: Targeting GP or CFAE? Evidence from Meta-Analysis of Clinical Trials

    PubMed Central

    Qin, Mu; Liu, Xu; Wu, Shao-Hui; Zhang, Xiao-Dong

    2016-01-01

    Several clinically relevant outcomes post atrial substrate modification in patients with atrial fibrillation (AF) have not been systematically analyzed among published studies on adjunctive cardiac ganglionated plexi (GP) or complex fractionated atrial electograms (CFAE) ablation vs. pulmonary vein isolation (PVI) alone. Out of 176 reports identified, the present meta-analysis included 14 randomized and non-randomized controlled trials (1613 patients) meeting inclusion criteria. Addition of GP ablation to PVI significantly increased freedom from atrial tachyarrhythmia in short- (OR: 1.72; P = 0.003) and long-term (OR: 2.0, P = 0.0006) follow-up, while adjunctive CFAE ablation did not after one or repeat procedure (P<0.05). The percentage of atrial tachycardia or atrial flutter (AT/AFL) after one procedure was higher for CFAE than GP ablation. In sub-analysis of non-paroxysmal AF, relative to PVI alone, adjunctive GP but not CFAE ablation significantly increased sinus rhythm maintenance (OR: 1.88, P = 0.01; and OR:1.24, P = 0.18, respectively). Meta regression analysis of the 14 studies indicated that sample size was significant source of heterogeneity either in outcomes after one or repeat procedure. In conclusion, in patients with AF, adjunctive GP but not CFAE ablation appeared to significantly add to the beneficial effects on sinus rhythm maintenance of PVI ablation alone; and CFAE ablation was associated with higher incidence of subsequent AT/AFL. PMID:27764185

  3. Atrial Substrate Modification in Atrial Fibrillation: Targeting GP or CFAE? Evidence from Meta-Analysis of Clinical Trials.

    PubMed

    Qin, Mu; Liu, Xu; Wu, Shao-Hui; Zhang, Xiao-Dong

    2016-01-01

    Several clinically relevant outcomes post atrial substrate modification in patients with atrial fibrillation (AF) have not been systematically analyzed among published studies on adjunctive cardiac ganglionated plexi (GP) or complex fractionated atrial electograms (CFAE) ablation vs. pulmonary vein isolation (PVI) alone. Out of 176 reports identified, the present meta-analysis included 14 randomized and non-randomized controlled trials (1613 patients) meeting inclusion criteria. Addition of GP ablation to PVI significantly increased freedom from atrial tachyarrhythmia in short- (OR: 1.72; P = 0.003) and long-term (OR: 2.0, P = 0.0006) follow-up, while adjunctive CFAE ablation did not after one or repeat procedure (P<0.05). The percentage of atrial tachycardia or atrial flutter (AT/AFL) after one procedure was higher for CFAE than GP ablation. In sub-analysis of non-paroxysmal AF, relative to PVI alone, adjunctive GP but not CFAE ablation significantly increased sinus rhythm maintenance (OR: 1.88, P = 0.01; and OR:1.24, P = 0.18, respectively). Meta regression analysis of the 14 studies indicated that sample size was significant source of heterogeneity either in outcomes after one or repeat procedure. In conclusion, in patients with AF, adjunctive GP but not CFAE ablation appeared to significantly add to the beneficial effects on sinus rhythm maintenance of PVI ablation alone; and CFAE ablation was associated with higher incidence of subsequent AT/AFL.

  4. Anatomical Substrates and Ablation of Reentrant Atrial and Ventricular Tachycardias in Repaired Congenital Heart Disease

    PubMed Central

    Brouwer, Charlotte; Hazekamp, Mark G

    2016-01-01

    Advances in surgical repair techniques for various types of congenital heart disease have improved survival into adulthood over the past decades, thus exposing these patients to a high risk of atrial and ventricular arrhythmias later in life. These arrhythmias arise from complex arrhythmogenic substrates. Substrate formation may depend on both pathological myocardial remodelling and variable anatomical boundaries, determined by the type and timing of prior corrective surgery. Accordingly, arrhythmogenic substrates after repair have changed as a result of evolving surgical techniques. Radiofrequency catheter ablation offers an important therapeutic option but remains challenging due to the variable anatomy, surgically created obstacles and the complex arrhythmogenic substrates. Recent technical developments including electroanatomical mapping and image integration for delineating the anatomy facilitate complex catheter ablation procedures. The purpose of this review is to provide an update on the changing anatomical arrhythmogenic substrates and their potential impact on catheter ablation in patients with repaired congenital heart disease and tachyarrhythmias. PMID:27617095

  5. An overview of energy sources in clinical use for the ablation of atrial fibrillation.

    PubMed

    Comas, George M; Imren, Yildirim; Williams, Mathew R

    2007-01-01

    Recent years have seen many developments in the field of alternative energy sources for arrhythmia surgery. The impetus behind these advances is to replace the traditional, "cut-and-sew" Cox maze III procedure with lesion sets that are simpler, shorter, and safer but just as effective. There is demand for technology to make continuous, linear, transmural ablations reliably with a versatile energy source via an epicardial approach. This would make minimally invasive endoscopic surgical ablation of atrial fibrillation (AF) without cardiopulmonary bypass and with a closed chest feasible. These advances would shorten cardio-pulmonary bypass and improve outcomes in patients having surgical ablation and concomitant cardiac surgery. This review summarizes the technology behind alternative energy sources used to treat AF. Alternative energy sources include hypothermic sources (cryoablation) and hyperthermic sources (radiofrequency, microwave, laser, ultrasound). For each source, the biophysical background, mode of tissue injury, factors affecting lesion size, and advantages and complications are discussed.

  6. New-onset ventricular arrhythmias post radiofrequency catheter ablation for atrial fibrillation

    PubMed Central

    Wu, Lingmin; Lu, Yanlai; Yao, Yan; Zheng, Lihui; Chen, Gang; Ding, Ligang; Hou, Bingbo; Qiao, Yu; Sun, Wei; Zhang, Shu

    2016-01-01

    Abstract As a new complication, new-onset ventricular arrhythmias (VAs) post atrial fibrillation (AF) ablation have not been well defined. This prospective study aimed to describe the details of new-onset VAs post AF ablation in a large study cohort. One thousand fifty-three consecutive patients who underwent the first radiofrequency catheter ablation for AF were enrolled. All patients had no evidence of pre-ablation VAs. New-onset VAs were defined as new-onset ventricular tachycardia (VT) or premature ventricular contractions (PVC) ≥1000/24 h within 1 month post ablation. There were 46 patients (4.4%) who had 62 different new-onset VAs, among whom 42 were PVC alone, and 4 were PVC coexisting with nonsustained VT. Multivariate analysis showed that increased serum leukocyte counts ≥50% post ablation were independently associated with new-onset VAs (OR: 1.9; 95% CI: 1.0–3.5; P = 0.043). The median number of PVC was 3161 (1001–27,407) times/24 h. Outflow tract VAs were recorded in 35 (76.1%) patients. No significant differences were found in origin of VAs (P = 0.187). VAs disappeared without any treatment in 6 patients (13.0%). No VAs-related adverse cardiac event occurred. The study revealed a noticeable prevalence but relatively benign prognosis of new-onset VAs post AF ablation. Increased serum leukocyte counts ≥50% post ablation appeared to be associated with new-onset VAs, implying that inflammatory response caused by ablation might be the mechanism. PMID:27603357

  7. Gender, Race, and Health Insurance Status in Patients Undergoing Catheter Ablation for Atrial Fibrillation.

    PubMed

    Patel, Nileshkumar; Deshmukh, Abhishek; Thakkar, Badal; Coffey, James O; Agnihotri, Kanishk; Patel, Achint; Ainani, Nitesh; Nalluri, Nikhil; Patel, Nilay; Patel, Nish; Patel, Neil; Badheka, Apurva O; Kowalski, Marcin; Hendel, Robert; Viles-Gonzalez, Juan; Noseworthy, Peter A; Asirvatham, Samuel; Lo, Kaming; Myerburg, Robert J; Mitrani, Raul D

    2016-04-01

    Catheter ablation for atrial fibrillation (AF) has emerged as a popular procedure. The purpose of this study was to examine whether there exist differences or disparities in ablation utilization across gender, socioeconomic class, insurance, or race. Using the Nationwide Inpatient Sample (2000 to 2012), we identified adults hospitalized with a principal diagnosis of AF by ICD 9 code 427.31 who had catheter ablation (ICD 9 code-37.34). We stratified patients by race, insurance status, age, gender, and hospital characteristics. A hierarchical multivariate mixed-effect model was created to identify the independent predictors of AF ablation. Among an estimated total of 3,508,122 patients (extrapolated from 20% Nationwide Inpatient Sample) hospitalized with a diagnosis of AF in the United States from the year 2000 to 2012, 102,469 patients (2.9%) underwent catheter ablations. The number of ablations was increased by 940%, from 1,439 in 2000 to 15,090 in 2012. There were significant differences according to gender, race, and health insurance status, which persisted even after adjustment for other risk factors. Female gender (0.83 [95% CI 0.79 to 0.87; p <0.001]), black (0.49 [95% CI 0.44 to 0.55; p <0.001]), and Hispanic race (0.64 [95% CI 0.56 to 0.72; p <0.001]) were associated with lower likelihoods of undergoing an AF ablation. Medicare (0.93, 0.88 to 0.98, <0.001) or Medicaid (0.67, 0.59 to 0.76, <0.001) coverage and uninsured patients (0.55, 0.49 to 0.62, <0.001) also had lower rates of AF ablation compared to patients with private insurance. In conclusion we found differences in utilization of catheter ablation for AF based on gender, race, and insurance status that persisted over time.

  8. Right atrial aneurysm with downward displacement of the anterior leaflet that resembled Ebstein's anomaly.

    PubMed

    Yamauchi, Sanae; Suzuki, Yasuyuki; Daitoku, Kazuyuki; Kimura, Masaomi; Okumura, Ken; Fukuda, Ikuo

    2016-06-08

    A 13-year-old boy presented with right atrial aneurysm and downward displacement of the anterior leaflet in the tricuspid valve into the right ventricle, without tricuspid valve regurgitation. Paroxysmal atrial flutter was caused by an abnormal electrical re-entry circuit, which could not be treated using catheter radiofrequency ablation. Therefore, the patient underwent surgical ablation and resection of the enlarged right atrial wall. The anterior leaflet of the tricuspid valve was plastered and displaced downward into the right ventricle, which resembled Ebstein's anomaly. Pathological evaluation revealed a thin wall that contained fibrous tissue with lipomatous degeneration and few muscular elements. No postoperative arrhythmia was observed.

  9. Lone Atrial Fibrillation Is Associated With Impaired Left Ventricular Energetics That Persists Despite Successful Catheter Ablation

    PubMed Central

    Wijesurendra, Rohan S.; Liu, Alexander; Eichhorn, Christian; Ariga, Rina; Levelt, Eylem; Clarke, William T.; Rodgers, Christopher T.; Karamitsos, Theodoros D.; Bashir, Yaver; Ginks, Matthew; Rajappan, Kim; Betts, Tim; Ferreira, Vanessa M.; Neubauer, Stefan

    2016-01-01

    Background: Lone atrial fibrillation (AF) may reflect a subclinical cardiomyopathy that persists after sinus rhythm (SR) restoration, providing a substrate for AF recurrence. To test this hypothesis, we investigated the effect of restoring SR by catheter ablation on left ventricular (LV) function and energetics in patients with AF but no significant comorbidities. Methods: Fifty-three patients with symptomatic paroxysmal or persistent AF and without significant valvular disease, uncontrolled hypertension, coronary artery disease, uncontrolled thyroid disease, systemic inflammatory disease, diabetes mellitus, or obstructive sleep apnea (ie, lone AF) undergoing ablation and 25 matched control subjects in SR were investigated. Magnetic resonance imaging quantified LV ejection fraction (LVEF), peak systolic circumferential strain (PSCS), and left atrial volumes and function, whereas phosphorus-31 magnetic resonance spectroscopy evaluated ventricular energetics (ratio of phosphocreatine to ATP). AF burden was determined before and after ablation by 7-day Holter monitoring; intermittent ECG event monitoring was also undertaken after ablation to investigate for asymptomatic AF recurrence. Results: Before ablation, both LV function and energetics were significantly impaired in patients compared with control subjects (LVEF, 61% [interquartile range (IQR), 52%–65%] versus 71% [IQR, 69%–73%], P<0.001; PSCS, –15% [IQR, –11 to –18%] versus −18% [IQR, –17% to –19%], P=0.002; ratio of phosphocreatine to ATP, 1.81±0.35 versus 2.05±0.29, P=0.004). As expected, patients also had dilated and impaired left atria compared with control subjects (all P<0.001). Early after ablation (1–4 days), LVEF and PSCS improved in patients recovering SR from AF (LVEF, 7.0±10%, P=0.005; PSCS, –3.5±4.3%, P=0.001) but were unchanged in those in SR during both assessments (both P=NS). At 6 to 9 months after ablation, AF burden reduced significantly (from 54% [IQR, 1.5%–100%] to

  10. [1:1 atrial flutter in an elderly patient: one of the methods of discovering Wolff-Parkinson-White syndrome. Apropos of a case in an adult].

    PubMed

    Parmeggiani, L; Adamec, R; Perrenoud, J J

    1984-01-01

    Atrial flutter with 1:1 atrioventricular conduction giving rise to a ventricular rhythm of 240/min in an 80 year old man was the first sign of the Wolff-Parkinson-White syndrome; all previous electrocardiogrammes had shown no evidence of pre-excitation. It was only on the fifth day of hospitalisation that the ECG showed a short PR interval with a delta wave. This case illustrates that: --all supraventricular arrhythmias with abnormally high ventricular rates (over 220/min in adults) should alert to the possibility of an accessory atrioventricular pathway; --rapid atrioventricular conduction may be the first sign of an accessory pathway; --the differential diagnosis lies between an accessory atrioventricular pathway and an atriohisian tract; --digitalis, which may shorten the refractory period of the accessory pathway, is contraindicated in patients with a Kent bundle.

  11. Atrial fibrillation or flutter

    MedlinePlus

    ... In: Mann DL, Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook ... In: Mann DL, Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook ...

  12. Seeing the Invisible: Revealing Atrial Ablation Lesions Using Hyperspectral Imaging Approach

    PubMed Central

    Muselimyan, Narine; Swift, Luther M.; Asfour, Huda; Chahbazian, Tigran; Mazhari, Ramesh; Mercader, Marco A.; Sarvazyan, Narine A.

    2016-01-01

    Background Currently, there are limited means for high-resolution monitoring of tissue injury during radiofrequency ablation procedures. Objective To develop the next generation of visualization catheters that can reveal irreversible atrial muscle damage caused by ablation and identify viability gaps between the lesions. Methods Radiofrequency lesions were placed on the endocardial surfaces of excised human and bovine atria and left ventricles of blood perfused rat hearts. Tissue was illuminated with 365nm light and a series of images were acquired from individual spectral bands within 420-720nm range. By extracting spectral profiles of individual pixels and spectral unmixing, the relative contribution of ablated and unablated spectra to each pixel was then displayed. Results of spectral unmixing were compared to lesion pathology. Results RF ablation caused significant changes in the tissue autofluorescence profile. The magnitude of these spectral changes in human left atrium was relatively small (< 10% of peak fluorescence value), yet highly significant. Spectral unmixing of hyperspectral datasets enabled high spatial resolution, in-situ delineation of radiofrequency lesion boundaries without the need for exogenous markers. Lesion dimensions derived from hyperspectral imaging approach strongly correlated with histological outcomes. Presence of blood within the myocardium decreased the amplitude of the autofluorescence spectra while having minimal effect on their overall shapes. As a result, the ability of hyperspectral imaging to delineate ablation lesions in vivo was not affected. Conclusions Hyperspectral imaging greatly increases the contrast between ablated and unablated tissue enabling visualization of viability gaps at clinically relevant locations. Data supports the possibility for developing percutaneous hyperspectral catheters for high-resolution ablation guidance. PMID:27930718

  13. Successful Non-fluoroscopic Radiofrequency Ablation of Incessant Atrial Tachycardia in a High Risk Twin Pregnancy.

    PubMed

    Zuberi, Zia; Silberbauer, John; Murgatroyd, Francis

    2014-01-01

    We describe a patient presenting with incessant ectopic atrial tachycardia during a high risk twin pregnancy. Tachycardia was resistant to escalating doses of beta-blockade with digoxin. Because of increasing left ventricular dysfunction early in the third trimester, catheter ablation was performed successfully at 30 weeks gestation. Electro-anatomic mapping permitted the entire procedure to be conducted without the use of ionizing radiation. The pregnancy proceeded to successful delivery near term and after three years the patient remains recurrence free with normal left ventricular function, off all medication.

  14. The Mid-Term Results of Patients who Underwent Radiofrequency Atrial Fibrillation Ablation Together with Mitral Valve Surgery

    PubMed Central

    Çolak, Abdurrahim; Kaya, Ugur; Ceviz, Munacettin; Becit, Necip; Kocak, Hikmet

    2016-01-01

    Objetive Saline-irrigated radiofrequency ablation, which has been widely used for surgical treatment of atrial fibrillation in recent years, is 80-90% successful in achieving sinus rhythm. In our study, our surgical experience and mid-term results in patients who underwent mitral valve surgery and left atrial radiofrequency ablation were analyzed. Methods Forty patients (15 males, 25 females; mean age 52.05±9.9 years; range 32-74) underwent surgery for atrial fibrillation associated with mitral valvular disease. All patients manifested atrial fibrillation, which started at least six months before the surgical intervention. The majority of patients (36 patients, 90%) were in NYHA class III; 34 (85%) patients had rheumatic heart disease. In addition to mitral valve surgery and radiofrequency ablation, coronary artery bypass, DeVega tricuspid annuloplasty, left ventricular aneurysm repair, and left atrial thrombus excision were performed. Following discharge from the hospital, patients' follow-up was performed as outpatient clinic examinations and the average follow-up period of patients was 18±3 months. Results While the incidence of sinus rhythm was 85.3% on the first postoperative day, it was 80% during discharge and 71% in the 1st year follow-up examination. Conclusion Radiofrequency ablation is an effective method when it is performed by appropriate surgical technique. Its rate for returning to sinus rhythm is as high as the rate of conventional surgical procedure. PMID:27849303

  15. Reduction of Fluoroscopy Time and Radiation Dosage During Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Aldhoon, Bashar; Kautzner, Josef

    2016-01-01

    Radiofrequency catheter ablation has become the treatment of choice for atrial fibrillation (AF) that does not respond to antiarrhythmic drug therapy. During the procedure, fluoroscopy imaging is still considered essential to visualise catheters in real-time. However, radiation is often ignored by physicians since it is invisible and the long-term risks are underestimated. In this respect, it must be emphasised that radiation exposure has various potentially harmful effects, such as acute skin injury, malignancies and genetic disease, both to patients and physicians. For this reason, every electrophysiologist should be aware of the problem and should learn how to decrease radiation exposure by both changing the setting of the system and using complementary imaging technologies. In this review, we aim to discuss the basics of X-ray exposure and suggest practical instructions for how to reduce radiation dosage during AF ablation procedures. PMID:27617094

  16. Role of Rotors in the Ablative Therapy of Persistent Atrial Fibrillation

    PubMed Central

    Schricker, Amir A; Zaman, Junaid; Narayan, Sanjiv M

    2015-01-01

    Atrial fibrillation (AF) ablation is increasingly used to maintain sinus rhythm yet its results are sub-optimal, especially in patients with persistent AF or prior unsuccessful procedures. Attempts at improvement have often targeted substrates that sustain AF after it is triggered, yet those mechanisms are debated. Many studies now challenge the concept that AF is driven by self-sustaining disordered wavelets, showing instead that localised drivers (rotors) may drive disorder via a process known as fibrillatory conduction. Novel mapping using wide-area recordings, physiological filtering and phase analysis demonstrates rotors in human AF. Contact mapping with focal impulse and rotor modulation (FIRM) shows that localised ablation at sources can improve procedural success in many populations on long-term follow up and some newer approaches to rotor mapping are qualitatively similar. This review critically evaluates the data on rotor mapping and ablation, which advances our conceptual understanding of AF and holds the promise of substantially improving ablative outcomes in patients with persistent AF. PMID:26835100

  17. CTS Trials Network: Surgical ablation of atrial fibrillation during mitral valve surgery - many questions unanswered.

    PubMed

    Afifi, Ahmed

    2015-01-01

    A disease that is associated with stroke and mortality, atrial fibrillation (AF) complicates 30 to 50% of mitral valve disease patients admitted for surgery.(1) Since the introduction of the Cox maze III procedure in 1992 many efforts have been made to come up with modified lesion sets and/or energy sources to surgically treat AF. This lead to the recently published American Heart Association (AHA)- American College of Cardiology (ACC)-Heart Rhythm Society (HRS) guidelines(2) stating that it is reasonable to perform atrial fibrillation ablation in selected patients undergoing other types of cardiac surgery. The effectiveness of different techniques in conversion to sinus rhythm and the clinical impact of freedom from AF remain a question. The CTS Trials Network have undertaken a trial to answer these questions. The first year results of their randomized trial comparing AF ablation at the time of mitral valve surgery with mitral valve surgery alone were published recently in The New England Journal of Medicine.(3).

  18. CTS Trials Network: Surgical ablation of atrial fibrillation during mitral valve surgery - many questions unanswered

    PubMed Central

    Afifi, Ahmed

    2015-01-01

    A disease that is associated with stroke and mortality, atrial fibrillation (AF) complicates 30 to 50% of mitral valve disease patients admitted for surgery.1 Since the introduction of the Cox maze III procedure in 1992 many efforts have been made to come up with modified lesion sets and/or energy sources to surgically treat AF. This lead to the recently published American Heart Association (AHA)– American College of Cardiology (ACC)–Heart Rhythm Society (HRS) guidelines2 stating that it is reasonable to perform atrial fibrillation ablation in selected patients undergoing other types of cardiac surgery. The effectiveness of different techniques in conversion to sinus rhythm and the clinical impact of freedom from AF remain a question. The CTS Trials Network have undertaken a trial to answer these questions. The first year results of their randomized trial comparing AF ablation at the time of mitral valve surgery with mitral valve surgery alone were published recently in The New England Journal of Medicine.3 PMID:26566527

  19. Pulmonary Vein Remodeling Following Atrial Fibrillation Ablation: Implications For The Radiographic Diagnosis Of Pulmonary Vein Stenosis.

    PubMed

    Merchant Md, Faisal M; Levy Bs, Mathew R; Iravanian Md, Shahriar; Weragoda Md, Ramal M; Clermont Md, Edward C; Kelli Md, Heval M; Eisner PhD, Robert L; Vadnais Md, David; El-Chami Md, Mikhael F; Leon Md, Angel R; Delurgio Md, David B

    2016-01-01

    Background: Pulmonary vein (PV) reverse remodeling has been recognized following atrial fibrillation (AF) ablation. However, the extent of physiologic reverse remodeling after AF ablation and the potential impact of reverse remodeling on the radiographic diagnosis of PV stenosis have not been well characterized. Methods: From January 2004 to February 2014, 186 patients underwent paired cardiac magnetic resonance imaging (MRI) to delineate PV orifice dimensions before and after (mean 109 ± 61 days) an initial AF ablation. Results: Negative remodeling of the PV orifice cross sectional area occurred in 67.8% of veins with a mean reduction in area of 21.0 ± 14.1%, and positive remodeling was seen in the remaining PVs with an increase in area of 22.1 ± 23.4% compared to baseline. No PVs demonstrated a reduction in cross-sectional area of > 75% (maximum reduction observed was 58%). Negative remodeling of the PV long axis dimension was observed in 55.2% of veins with a mean reduction of 14.6 ± 9.2% compared to pre-ablation and positive remodeling was observed in 25.3% of PVs with a mean increase in diameter of 14.7 ± 12.6%. Only 1 PV demonstrated a reduction in orifice diameter of > 50%. There were no clinically evident or suspected cases of PV stenosis in this cohort. Conclusions: Negative remodeling of the PV orifice area was noted in the majority of PVs following AF ablation. However, in almost all cases, the extent of negative remodeling was well below commonly used thresholds for the radiographic diagnosis of PV stenosis.

  20. Successful catheter ablation of incessant atrial tachycardia in pregnancy using three-dimensional electroanatomical mapping with minimal radiation.

    PubMed

    Wu, H; Ling, L-H; Lee, G; Kistler, P M

    2012-06-01

    Arrhythmias during pregnancy are not an infrequent problem and present a difficult therapeutic challenge to physicians. Anti-arrhythmic medication is used with some trepidation given concerns for the unborn foetus. Catheter ablation is typically avoided due to concerns regarding foetal exposure to radiation and delayed until the post-partum period. With the availability of three-dimensional mapping systems, catheter ablation may be performed with minimal radiation. We report a pregnant woman who underwent successful ablation of focal atrial tachycardia using three-dimensional electroanatomical mapping with minimal radiation exposure.

  1. Robust tracking of a virtual electrode on a coronary sinus catheter for atrial fibrillation ablation procedures

    NASA Astrophysics Data System (ADS)

    Wu, Wen; Chen, Terrence; Strobel, Norbert; Comaniciu, Dorin

    2012-02-01

    Catheter tracking in X-ray fluoroscopic images has become more important in interventional applications for atrial fibrillation (AF) ablation procedures. It provides real-time guidance for the physicians and can be used as reference for motion compensation applications. In this paper, we propose a novel approach to track a virtual electrode (VE), which is a non-existing electrode on the coronary sinus (CS) catheter at a more proximal location than any real electrodes. Successful tracking of the VE can provide more accurate motion information than tracking of real electrodes. To achieve VE tracking, we first model the CS catheter as a set of electrodes which are detected by our previously published learning-based approach.1 The tracked electrodes are then used to generate the hypotheses for tracking the VE. Model-based hypotheses are fused and evaluated by a Bayesian framework. Evaluation has been conducted on a database of clinical AF ablation data including challenging scenarios such as low signal-to-noise ratio (SNR), occlusion and nonrigid deformation. Our approach obtains 0.54mm median error and 90% of evaluated data have errors less than 1.67mm. The speed of our tracking algorithm reaches 6 frames-per-second on most data. Our study on motion compensation shows that using the VE as reference provides a good point to detect non-physiological catheter motion during the AF ablation procedures.2

  2. The mechanism of lesion formation by focused ultrasound ablation catheter for treatment of atrial fibrillation

    NASA Astrophysics Data System (ADS)

    Sinelnikov, Y. D.; Fjield, T.; Sapozhnikov, O. A.

    2009-10-01

    The application of therapeutic ultrasound for the treatment of atrial fibrillation (AF) is investigated. The results of theoretical and experimental investigation of ultrasound ablation catheter are presented. The major components of the catheter are the high power cylindrical piezoelectric element and parabolic balloon reflector. Thermal elevation in the ostia of pulmonary veins is achieved by focusing the ultrasound beam in shape of a torus that transverses the myocardial tissue. High intensity ultrasound heating in the focal zone results in a lesion surrounding the pulmonary veins that creates an electrical conduction blocks and relief from AF symptoms. The success of the ablation procedure largely depends on the correct choice of reflector geometry and ultrasonic power. We present a theoretical model of the catheter’s acoustic field and bioheat transfer modeling of cardiac lesions. The application of an empirically derived relation between lesion formation and acoustic power is shown to correlate with the experimental data. Developed control methods combine the knowledge of theoretical acoustics and the thermal lesion formation simulations with experiment and thereby establish dosimetry that contributes to a safe and effective ultrasound ablation procedure.

  3. Factors related to sinus rhythm at discharge after radiofrequency ablation of permanent atrial fibrillation in patients undergoing mitral valve surgery.

    PubMed

    Rostagno, Carlo; Gelsomino, Sandro; Capecchi, Irene; Rossi, Alessandra; Montesi, Gian Franco; Stefàno, Pier Luigi

    2016-04-01

    Late recovery of sinus rhythm is unusual in patients with permanent AF treated by (radiofrequency) RF maze procedure during mitral valve surgery. Identification of clinical and instrumental preoperative factors predictive of early success of RF ablation in patients with permanent AF undergoing mitral valve surgery may improve selection of subjects to obtain long-term results. Hundred and thirty consecutive patients with permanent AF and mitral valve disease underwent modified RF maze procedure during concomitant mitral valve surgery. Rheumatic valve disease (61 pts) and mitral valve prolapse (41 pts) were the more common aetiology of valve abnormalities. Mitral valve replacement was performed in 54 % of patients and mitral valve repair in the remaining 46 %. Four patients died after surgery. At discharge, 87 patients (69 %) were in sinus rhythm (group 1) and 43 patients in AF persisted (group 2). At an average 24-month follow-up, sinus rhythm was present in 67 % of patients, and 33 % were in atrial fibrillation. In this period, late recovery of sinus rhythm was observed only in five patients, while eight discharged in sinus rhythm developed again atrial fibrillation. Among preoperative parameters at univariate analysis female sex, atrial fibrillation >24 months, left atrial diameter >54 mm, left atrial area >24 cm(2), rheumatic valve disease and NYHA class were associated with persistence of AF. At Cox regression multivariate analysis, increased left atrial area (OR 1.07 per unit increase-95 % CI 1.01-1.131) and rheumatic aetiology of valve disease (OR 4.52, 95 % CI 1.65-12.4) were associated with persistence of AF at hospital discharge. Persistence of AF after RF ablation in patients undergoing mitral valve surgery is related to aetiology, e.g. rheumatic valve disease, and to increasing left atrial diameter. Due to low rate of late recovery of sinus rhythm, indication to RF ablation associated with MV surgery should be carefully considered in patients with large

  4. Pre-ablative high-resolution MRA facilitates electrophysiologic pulmonary vein ablation and reduces fluoroscopy time in patients with paroxysmal atrial fibrillation

    NASA Astrophysics Data System (ADS)

    Collins, Jeremy D.; Pereles, F. S.; Bello, David; Betts, Timothy; Zachariah, Anish; Kaliney, Ryan; Song, Gina K.; Shors, Stephanie M.; Carr, James C.; Finn, John P.

    2003-05-01

    Pulmonary MRA generates high-resolution images of the pulmonary veins (PV) and left atrium (LA), permitting characterization of complex PV anatomy, which is useful in electrophysiologic PV catheter ablation, a proven technique for the treatment of paroxysmal atrial fibrillation (PAF). The purpose of this study was to determine if pre-ablative pulmonary MRA with intra-ablative viewing facilitates ablation by reducing fluoroscopy time. We studied the morphology of the LA and PV at 1.5T (Magnetom Sonata, Siemens Medical Solutions, Erlangen Germany) with breath-held gadolinium-enhanced 3D MRA in 7 patients with PAF undergoing PV ablation. Data was volume rendered (VR) on a stereoscopic workstation. PV ostial diameter and cross-sectional area measurements were obtained on multi-planar reformatted (MPR) images. VR datasets were converted into digital movies and were viewed on a laptop computer adjacent to real-time fluoroscopic images. Fluoroscopy times for patients undergoing pre-ablative MPA mapping were compared with a cohort of 22 consecutive patients diagnosed with PAF who underwent catheter ablation without pre-ablative MRA planning. Mean PV ablation fluoroscopic time with MRA planning versus fluoroscopic imaging alone were 84+/-20 minutes and 114+/-20 minutes respectively. Pre-ablative MRA planning resulted in a significant mean fluoroscopy time savings of 26% (p<0.05). In patients with PAF undergoing PV ablation, analysis of MRA datasets depicting PV anatomy confirms that there is great variability in anatomy between veins. Pre-ablative 3D PV mapping by MRA greatly facilitates fluoroscopic identification of individual veins and significantly reduces fluoroscopic radiation time.

  5. Hiatal hernia squeezing the heart to flutter.

    PubMed

    Patel, Arpan; Shah, Rushikesh; Nadavaram, Sravanthi; Aggarwal, Aakash

    2014-04-01

    An 80-year-old woman presented to the emergency department with failure to thrive and weakness for 14 days. Medical history was significant for polio. On admission her electrocardiogram showed atrial flutter, and cardiac enzymes were elevated. Echocardiogram revealed a high pulmonary artery pressure, but no other wall motion abnormalities or valvulopathies. Chest x-ray showed a large lucency likely representing a diaphragmatic hernia. Computed tomographic scan confirmed the hernia. Our patient remained in atrial flutter despite rate control, and thereafter surgery was consulted to evaluate the patient. She underwent hernia repair. After surgery, the patient was taken off rate control and monitored for 72 hours; she did not have any episode of atrial flutter and was discharged with follow up in a week showing no arrhythmia. Her flutter was caused directly by the mechanical effect of the large hiatal hernia pressing against her heart, as the flutter resolved after the operation.

  6. Dual-enhancement cardiac computed tomography for assessing left atrial thrombus and pulmonary veins before radiofrequency catheter ablation for atrial fibrillation.

    PubMed

    Hur, Jin; Pak, Hui-Nam; Kim, Young Jin; Lee, Hye-Jeong; Chang, Hyuk-Jae; Hong, Yoo Jin; Choi, Byoung Wook

    2013-07-15

    Noninvasive imaging that provides anatomic information while excluding intracardiac thrombus would be of significant clinical value for patients referred for catheter ablation of atrial fibrillation (AF). This study assessed the diagnostic performance of a dual-enhancement single-phase cardiac computed tomography (CT) protocol for thrombus and circulatory stasis detection in AF patients before catheter ablation. We studied 101 consecutive symptomatic AF patients (71 men and 30 women; mean age, 61.8 years) who were scheduled to have catheter ablation. All patients had undergone pre-AF ablation CT imaging and transesophageal echocardiography on the same day. CT was performed with prospective electrocardiographic gating, and scanning began 180 seconds after the test bolus. Mean left atrial appendage (LAA)/ascending aorta Hounsfield unit (HU) ratios were measured on CT images. Among the 101 patients, 9 thrombi and 18 spontaneous echo contrasts were detected by transesophageal echocardiography. The overall sensitivity, specificity, positive predictive value, and negative predictive value of CT for the detection of thrombi in the LAA were 89%, 100%, 100%, and 99%, respectively. The mean LAA/ascending aorta HU ratios were significantly different between thrombus and circulatory stasis (0.17 vs 0.33, p = 0.002). Dual-enhancement single-scan cardiac CT is a sensitive modality for detecting and differentiating LAA thrombus and circulatory stasis.

  7. Concomitant surgical atrial fibrillation ablation and event recorder implantation: better monitoring, better outcome?†

    PubMed Central

    Pecha, Simon; Schäfer, Timm; Hartel, Friederike; Ahmadzade, Teymour; Subbotina, Irina; Reichenspurner, Hermann; Wagner, Florian Matthias

    2013-01-01

    OBJECTIVES Concomitant ablation is an established therapy in cardiac surgical patients with atrial fibrillation (AF). Post-discharge care seems to be an essential factor for clinical outcome. We analysed the influence of event recorder (ER) implantation and therapy guidance by the results of continuous rhythm monitoring of consecutive postoperative follow-up by our department of electrophysiology. METHODS Between July 2003 and August 2010, 401 cardiac surgical patients underwent concomitant surgical AF ablation therapy. Since August 2009, an ER (REVEAL XT, Medtronic, Inc., Minneapolis, MN, USA) was implanted in 98 patients intraoperatively. ER interrogation was performed by our department of electrophysiology 3, 6 and 12 months postoperatively. Results and outcomes were compared with a matched cohort of patients with ablation and no ER implantation. In those patients, rhythm follow-up was obtained by 24-h Holter ECG. Primary end-point of the study was sinus rhythm rate after 12 months. RESULTS Mean patient's age was 67.0 ± 9.7 years, and 68.4% were male. No major ablation-related complications occurred. The overall sinus rhythm rate was 65.3% after 1-year follow-up. The sinus rhythm rate off antiarrhythmic drugs was 60.3%. The conversion rate tended to be higher in patients with an implanted ER (69.3 vs 60.1%, respectively; P = 0.098). Also, the sinus rhythm rate of anti-arrhythmic drugs was higher in the ER group (64.3 vs 56.2). Patients with ER were seen more often by a cardiologist in the first postoperative year (3.1 ± 0.8 vs 1.5 ± 0.9; P < 0.05) and received significantly more additional procedures, like electrical cardioversion or additional catheter-based ablation (16.1 vs 4.3%; P < 0.001; 11.2 vs 3.1%; P < 0.001). CONCLUSIONS Implantation of an ER with link-up to a cardiology and/or electrophysiology provides optimized anti-arrhythmic drug management and higher rates of consecutive procedures like cardioversion or additional catheter-based ablation. As a

  8. Oral anticoagulant therapy for stroke prevention in patients with atrial fibrillation undergoing ablation: results from the First European Snapshot Survey on Procedural Routines for Atrial Fibrillation Ablation (ESS-PRAFA).

    PubMed

    Potpara, Tatjana S; Larsen, Torben B; Deharo, Jean Claude; Rossvoll, Ole; Dagres, Nikolaos; Todd, Derick; Pison, Laurent; Proclemer, Alessandro; Purefellner, Helmut; Blomström-Lundqvist, Carina

    2015-06-01

    The European Snapshot Survey on Procedural Routines in Atrial Fibrillation Ablation (ESS-PRAFA) is a prospective, multicentre snapshot survey of patients undergoing atrial fibrillation (AF) ablation, conducted to collect patient-based data on current clinical practices in AF ablation in context of the latest AF Guidelines and contemporary oral anticoagulant therapies. The EP Research Network Centres were asked to prospectively enrol consecutive patients during a 6-week period (September/October 2014). Data were collected via the web-based case report form. We present the results pertinent to the use of antithrombotic therapies. Thirteen countries prospectively enrolled 455 eligible consecutive patients [mean age 59 ± 10.8 years, 131 (28.8%) females]. The mean CHA2DS2-VASc score was 1.12 ± 1.06 [137 patients (30.1%) had a score of ≥2]. Before ablation, 443 patients (97.4%) were on anticoagulant therapy [143 (31.4%) on non-vitamin K antagonist oral anticoagulants (NOACs) and 264 (58.0%) on vitamin K antagonists (VKAs)]. Of the latter, 79.7% underwent ablation without VKA interruption, whilst a variety of strategies were used in patients taking NOAC. After ablation, most patients (89.3%) continued the same anticoagulant as before, and 2 (0.4%) were not prescribed any anticoagulation. At discharge, 280 patients (62.2%) were advised oral anticoagulation for a limited period of mean 3.8 ± 2.2 months. On multivariate analysis, CHA2DS2-VASc, AF duration, prior VKA use, and estimated AF ablation success were significantly associated with the decision on short-term anticoagulation. Our results show the increasing use of NOAC in patients undergoing AF ablation and emphasize the need for more information to guide the periprocedural use of both NOACs and VKAs in real-world setting.

  9. Optimal transseptal puncture location for robot-assisted left atrial catheter ablation.

    PubMed

    Jayender, Jagadeesan; Patel, Rajni V; Michaud, Gregory F; Hatal, Nobuhiko

    2009-01-01

    The preferred method of treatment for Atrial Fibrillation (AF) is by catheter ablation wherein a catheter is guided into the left atrium through a transseptal puncture. However, the transseptal puncture constrains the catheter, thereby limiting its maneuverability and increasing the difficulty in reaching various locations in the left atrium. In this paper, we address the problem of choosing the optimal transseptal puncture location for performing cardiac ablation to obtain maximum maneuverability of the catheter. We have employed an optimization algorithm to maximize the Global Isotropy Index (GII) to evaluate the optimal transseptal puncture location. As part of this algorithm, a novel kinematic model for the catheter has been developed based on a continuum robot model. Preoperative MR/CT images of the heart are segmented using the open source image-guided therapy software, Slicer 3, to obtain models of the left atrium and septal wall. These models are input to the optimization algorithm to evaluate the optimal transseptal puncture location. Simulation results for the optimization algorithm are presented in this paper.

  10. Navigation for fluoroscopy-guided cryo-balloon ablation procedures of atrial fibrillation

    NASA Astrophysics Data System (ADS)

    Bourier, Felix; Brost, Alexander; Kleinoeder, Andreas; Kurzendorfer, Tanja; Koch, Martin; Kiraly, Attila; Schneider, Hans-Juergen; Hornegger, Joachim; Strobel, Norbert; Kurzidim, Klaus

    2012-02-01

    Atrial fibrillation (AFib), the most common arrhythmia, has been identified as a major cause of stroke. The current standard in interventional treatment of AFib is the pulmonary vein isolation (PVI). PVI is guided by fluoroscopy or non-fluoroscopic electro-anatomic mapping systems (EAMS). Either classic point-to-point radio-frequency (RF)- catheter ablation or so-called single-shot-devices like cryo-balloons are used to achieve electrically isolation of the pulmonary veins and the left atrium (LA). Fluoroscopy-based systems render overlay images from pre-operative 3-D data sets which are then merged with fluoroscopic imaging, thereby adding detailed 3-D information to conventional fluoroscopy. EAMS provide tracking and visualization of RF catheters by means of electro-magnetic tracking. Unfortunately, current navigation systems, fluoroscopy-based or EAMS, do not provide tools to localize and visualize single shot devices like cryo-balloon catheters in 3-D. We present a prototype software for fluoroscopy-guided ablation procedures that is capable of superimposing 3-D datasets as well as reconstructing cyro-balloon catheters in 3-D. The 3-D cyro-balloon reconstruction was evaluated on 9 clinical data sets, yielded a reprojected 2-D error of 1.72 mm +/- 1.02 mm.

  11. Reduction of radiation exposure in catheter ablation of atrial fibrillation: Lesson learned

    PubMed Central

    De Ponti, Roberto

    2015-01-01

    Over the last decades, the concern for the radiation injury hazard to the patients and the professional staff has increased in the medical community. Since there is no magnitude of radiation exposure that is known to be completely safe, the use of ionizing radiation during medical diagnostic or interventional procedures should be as low as reasonably achievable (ALARA principle). Nevertheless, in cardiovascular medicine, radiation exposure for coronary percutaneous interventions or catheter ablation of cardiac arrhythmias may be high: for ablation of a complex arrhythmia, such as atrial fibrillation, the mean dose can be > 15 mSv and in some cases > 50 mSv. In interventional electrophysiology, although fluoroscopy has been widely used since the beginning to navigate catheters in the heart and the vessels and to monitor their position, the procedure is not based on fluoroscopic imaging. Therefore, non-fluoroscopic three-dimensional systems can be used to navigate electrophysiology catheters in the heart with no or minimal use of fluoroscopy. Although zero-fluoroscopy procedures are feasible in limited series, there may be difficulties in using no fluoroscopy on a routine basis. Currently, a significant reduction in radiation exposure towards near zero-fluoroscopy procedures seems a simpler task to achieve, especially in ablation of complex arrhythmias, such as atrial fibrillation. The data reported in the literature suggest the following three considerations. First, the use of the non-fluoroscopic systems is associated with a consistent reduction in radiation exposure in multiple centers: the more sophisticated and reliable this technology is, the higher the reduction in radiation exposure. Second, the use of these systems does not automatically lead to reduction of radiation exposure, but an optimized workflow should be developed and adopted for a safe non-fluoroscopic navigation of catheters. Third, at any level of expertise, there is a specific learning curve for

  12. The Effectiveness of Surgical Ablation in Patients with Atrial Fibrillation and Aortic Valve Disease

    PubMed Central

    Henn, Matthew C.; Lawrance, Christopher P.; Sinn, Laurie A.; Miller, Jacob R.; Schuessler, Richard B.; Moon, Marc R.; Melby, Spencer J.; Maniar, Hersh S.; Damiano, Ralph J.

    2015-01-01

    Background In patients with atrial fibrillation(AF), the addition of surgical ablation to aortic valve replacement(AVR) does not increase procedural morbidity or mortality. However, efficacy in this population has not been carefully evaluated. This study compared outcomes between patients undergoing stand-alone Cox-Maze IV to those undergoing surgical ablation and concomitant AVR. Methods From January 2002 to May 2014, 188 patients received a stand-alone Cox-maze IV(n=113) or surgical ablation with concomitant AVR(n=75). In the concomitant AVR group, patients underwent Cox-maze IV(n=58), left-sided Cox-maze IV(n=3), or pulmonary vein isolation(n=14). Thirty-one perioperative variables were compared. Freedoms from AF on and off antiarrhythmic drugs were evaluated at 3, 6, 12, and 24 months. Results Follow up was available in 97% of patients. Freedom from AF on and off antiarrhythmic drugs in patients receiving a stand-alone Cox-maze IV vs. concomitant AVR was not significantly different at any time point. The concomitant AVR group had more comorbidities, paroxysmal AF, pacemaker implantations(24% vs. 5%, p=0.002), and complications(25% vs. 5%, p<0.001). Freedoms from AF off antiarrhythmic drugs for patients receiving an AVR and pulmonary vein isolation at 1 year was only 50%, which was significantly lower than patients receiving an AVR and Cox-maze IV(94%, p=0.001). Conclusions A Cox-maze IV with concomitant AVR is as effective as a stand-alone Cox-maze IV in treating AF, even in an older population with more comorbidities. Pulmonary vein isolation was not as effective and is not recommended in this population. A Cox-maze IV should be considered all in patients undergoing AVR with a history of AF. PMID:26209496

  13. Silent Cerebral Events after Atrial Fibrillation Ablation - Overview and Current Data.

    PubMed

    Deneke, Thomas; Nentwich, Karin; Krug, Joachim; Müller, Patrick; Grewe, Peter Hubert; Mügge, Andreas; Schade, Anja

    2014-01-01

    Silent cerebral lesions (SCL) have been identified on brain magnetic resonance imaging (MRI) in apparently asymptomatic patients after cardiovascular procedures. After atrial fibrillation (AF) ablation incidences range from 1 to over 40% depending upon different factors. MRI definition should include diffusion weighted imaging (DWI) to detect hyperintensities (bright spots) due to acute brain ischemia correlated with a hypointensity in the apparent diffusion coefficient mapping (ADC-map) to rule out artifacts. The genesis of SCL appears to be multifactorial and appears to be a result of embolic events either from gaseous or solid particles. The MRI pattern appears to be comparable not hinting towards a specific mechanism. One may distinguish two different MRI definition: one, more sensitive, for silent ischemic events (SCE) not proven to be related to cell death (DWI positive but FLAIR negative); and one for SCL that are due to edema caused by cell death which will lead to glial cell scar formation (DWI positive and FLAIR positive). For ease of data interpretation, future studies should ensure both definitions, and that DWI and FLAIR data is acquired using identical slice thickness and orientation. Risk factors associated with increased SCL-incidences involve patient-specific, technology-associated and procedural determinants. When using a high-sensitive MRI definition differences in SCE-rates in between technologies appear to be less prominent. Further studies on the effects of different periprocedural anticoagulation regimen, different steps of the ablation procedure and new technologies are needed. For now, SCL incidence may determine the thrombogenic potential of an ablation technology and further studies to reduce or avoid SCL generation are desirable. It appears reasonable, that any SCE should be avoided.

  14. Initial outcome following invasive cardiac electrophysiologic studies and radiofrequency ablation of atrial fibrillation

    PubMed Central

    Uwanuruochi, Kelechukwu; Saravanan, Sabari; Ganasekar, Anita; Solomon, Benjamin S; Murugesan, Ravikumar; Shah, Ruchit A; Krishnamoorthy, Jaishankar; Pandurangi, Ulhas M

    2016-01-01

    Background: Cardiac electrophysiologic study and radiofrequency ablation (RFA) have become an established mode of treatment for patients with refractory arrhythmias. These procedures are carried out regularly at the cardiac catheterization laboratory of Madras Medical Mission India. Objective: The purpose of this study was to evaluate our experience with cardiac electrophysiologic studies (EPS) and RFA catheter of atrial fibrillation (AF). Materials and Methods: This was a retrospective study carried out in the Cardiac Electrophysiology Department of the Institute of Cardiovascular Diseases, Madras Medical Mission, India. All cases diagnosed to have AF following cardiac EPS between January 2010 and April 2014 was selected for the study. The records, which were obtained from the Cardiac Electrophysiology Clinical Research Office of Madras Medical Mission, were reviewed. Forty-nine cases were chosen for analysis, using SPSS statistical software version 15. Results: There were 49 patients, 23 males and 26 females. The mean age was 57.53 years. Commonly associated diseases were diabetes mellitus 8 (16.3%), hypertension 18 (36.7%), and coronary heart disease 14 (28.5%). The ventricular rate was rapid most cases (91.2%). AF was diagnosed as being paroxysmal in 40 (81.6%), persistent in 5 (10.2%), chronic in 3 (6.1%), and lone in 1 (2.0%). Ablation was carried out in 28 (57.1%), the success rate being 90% for pulmonary vein isolation, and 90.9% for atrioventricular node ablation. Complication rate was 2.04%. Conclusions: Treatment of AF by RFA is highly effective and safe. PMID:27127736

  15. Uncontrolled ventricular rate in atrial fibrillation. A manifestation of dissimilar atrial rhythms.

    PubMed Central

    Leier, C V; Johnson, T M; Lewis, R P

    1979-01-01

    A patient with coarse atrial fibrillation and a rapid ventricular response developed periods of high grade atrioventricular block interpersed with periods of rapid ventricular conduction after the administration of digitalis and propranolol. Intracardiac atrial recordings showed similar atrial rhythms of high right atrial flutter and left atrial fibrillation. The low right atrial recordings showed flutter during the periods of fast ventricular rates and fibrillation during periods of slower ventricular rates. Images PMID:475927

  16. Primary Cardiac Sarcoidosis with Syncope and Refractory Atrial Arrhythmia: A Case Report and Review of the Literature

    PubMed Central

    Thangam, Manoj; Nathan, Sriram; Kar, Biswajit; Petrovic, Marija; Patel, Manish; Loyalka, Pranav; Buja, L. Maximilian

    2016-01-01

    We discuss the case of a 38-year-old black man who presented at our hospital with his first episode of syncope, recently developed atrial arrhythmias refractory to pharmacologic therapy, and a left atrial thrombus. He was diagnosed with primary cardiac sarcoidosis characterized by predominant involvement of the epicardium that caused atrial fibrillation and atrial flutter. Histologic analysis of his epicardial lesions yielded a diagnosis of sarcoidosis. This patient's atrial arrhythmia was successfully treated with a hybrid operation that involved resection of his atrial appendage, an Epicor maze procedure, and radiofrequency ablation during a catheter-based electrophysiologic study. The cardiac sarcoidosis was successfully managed with corticosteroid therapy. Our case report shows that sarcoidosis can initially manifest itself as syncope with new-onset atrial arrhythmia. Sarcoidosis is important in the differential diagnosis because of its progressive nature and its potential for treatment with pharmacologic, surgical, and catheter-based interventions. PMID:27303240

  17. Hybrid therapy in the management of atrial fibrillation.

    PubMed

    Starek, Zdenk; Lehar, Frantisek; Jez, Jiri; Wolf, Jiri; 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.

  18. Six year follow-up after catheter ablation of atrial fibrillation: a palliation more than a true cure.

    PubMed

    Sorgente, Antonio; Tung, Patricia; Wylie, Jack; Josephson, Mark E

    2012-04-15

    Long-term outcomes after pulmonary vein isolation for atrial fibrillation (AF) remain uncertain. In particular, the influence of rigorous arrhythmia monitoring on outcomes is not yet clear. In this study, 103 patients with symptomatic AF who underwent catheter ablation at a single academic medical center from 2002 to 2006 were evaluated, with a median follow-up time of 6 years. The primary end point was the success rate of catheter ablation, defined as the absence of any atrial arrhythmia recurrence lasting >10 seconds at the clinical visit and electrocardiographic or long-term cardiac rhythm recording after a single procedure and after the last procedure. In all, 153 procedures were performed, with a median of 1 (interquartile range 1 to 2) per patient as follows: 61 had 1, 35 had 2, 6 had 3, and 1 had 4 catheter ablations. Freedom from all atrial arrhythmias was present in 23% of patients at 6 years after a single procedure and in 39% of patients after the last procedure. No clinical predictors of AF recurrence were recognized after a single procedure, whereas after the last procedure, in univariate and multivariate Cox regression analysis, only nonparoxysmal AF (hazard ratio 1.92, 95% confidence interval 1.07 to 3.47, p = 0.02) was a predictor of recurrence. In conclusion, AF recurrence at 6-year follow-up after catheter ablation in a selected group of patients with symptomatic drug-refractory AF was relatively high, with 2/3 of AF relapses occurring in the first year of follow-up. Strict clinical surveillance after catheter ablation should be considered to help guide clinical decisions.

  19. A simulation study to compare the phase-shift angle radiofrequency ablation mode with bipolar and unipolar modes in creating linear lesions for atrial fibrillation ablation.

    PubMed

    Yan, Shengjie; Wu, Xiaomei; Wang, Weiqi

    2016-05-01

    Purpose In pulmonary veins (PVs) isolation (PVI), radiofrequency (RF) energy is often used to create a linear lesion for blocking the accessory conduction pathways around PVs. By using transient finite element analysis, this study compared the effectiveness of phase-shift mode (PsM) ablation with bipolar mode (BiM) and unipolar mode (UiM) in creating a continuous lesion and lesion depth in a 5-mm thick atrial wall. Materials and methods Computer models were developed to study the temperature distributions and lesion dimensions in atrial walls created through PsM, BiM, and UiM. Four phase-shift angles - 45°, 90°, 135°, and 180° - were considered in PsM ablation (hereafter, PsM-45°, PsM-90°, PsM-135°, and PsM-180°, respectively). Results At 60 s/30 V peak value of RF voltage, UiM and PsM-45° did not create an effective lesion, whereas BiM created a lesion of maximum depth and width approximately 1.01 and 1.62 mm, respectively. PsM-135° and PsM-180° not only created transmural lesions in 5-mm thick atrial walls but also created continuous lesions between electrodes spaced 4 mm apart; similarly, PsM-90° created a continuous lesion with a maximum depth and width of nearly 4.09 and 6.12 mm. Conclusions Compared with UiM and BiM, PsM-90°, PsM-135° and PsM-180° created continuous and larger lesions in a single ablation procedure and at 60 s/30 V peak value of RF voltage. Therefore, the proposed PsM ablation method is suitable for PVI and linear isolation at the left atrial roof for treating atrial fibrillation.

  20. Analysis of left atrial respiratory and cardiac motion for cardiac ablation therapy

    NASA Astrophysics Data System (ADS)

    Rettmann, M. E.; Holmes, D. R.; Johnson, S. B.; Lehmann, H. I.; Robb, R. A.; Packer, D. L.

    2015-03-01

    Cardiac ablation therapy is often guided by models built from preoperative computed tomography (CT) or magnetic resonance imaging (MRI) scans. One of the challenges in guiding a procedure from a preoperative model is properly synching the preoperative models with cardiac and respiratory motion through computational motion models. In this paper, we describe a methodology for evaluating cardiac and respiratory motion in the left atrium and pulmonary veins of a beating canine heart. Cardiac catheters were used to place metal clips within and near the pulmonary veins and left atrial appendage under fluoroscopic and ultrasound guidance and a contrast-enhanced, 64-slice multidetector CT scan was collected with the clips in place. Each clip was segmented from the CT scan at each of the five phases of the cardiac cycle at both end-inspiration and end-expiration. The centroid of each segmented clip was computed and used to evaluate both cardiac and respiratory motion of the left atrium. A total of three canine studies were completed, with 4 clips analyzed in the first study, 5 clips in the second study, and 2 clips in the third study. Mean respiratory displacement was 0.2+/-1.8 mm in the medial/lateral direction, 4.7+/-4.4 mm in the anterior/posterior direction (moving anterior on inspiration), and 9.0+/-5.0 mm superior/inferior (moving inferior with inspiration). At end inspiration, the mean left atrial cardiac motion at the clip locations was 1.5+/-1.3 mm in the medial/lateral direction, and 2.1+/-2.0 mm in the anterior/posterior and 1.3+/-1.2 mm superior/inferior directions. At end expiration, the mean left atrial cardiac motion at the clip locations was 2.0+/-1.5mm in the medial/lateral direction, 3.0+/-1.8mm in the anterior/posterior direction, and 1.5+/-1.5 mm in the superior/inferior directions.

  1. Designing Comparative Effectiveness Trials of Surgical Ablation for Atrial Fibrillation: Experience of the Cardiothoracic Surgical Trials Network

    PubMed Central

    Gillinov, A. Marc; Argenziano, Michael; Blackstone, Eugene H.; Iribarne, Alexander; DeRose, Joseph J.; Ailawadi, Gorav; Russo, Mark J.; Ascheim, Deborah D.; Parides, Michael K.; Rodriguez, Evelio; Bouchard, Denis; Taddei-Peters, Wendy C.; Geller, Nancy L.; Acker, Michael A.; Gelijns, Annetine C.

    2013-01-01

    Background Since the introduction of the cut-and-sew Cox-Maze procedure for atrial fibrillation (AF) there has been substantial innovation in techniques for ablation. Use of alternate energy sources for ablation simplified the procedure and has resulted in dramatic increase in the number of AF patients treated by surgical ablation. Despite its increasingly widespread adoption, there is lack of rigorous clinical evidence to establish this as an effective clinical therapy. Methods and Results This paper describes a comparative effectiveness randomized trial, supported by the Cardiothoracic Surgical Trials Network, of surgical ablation with left atrial appendage (LAA) closure versus LAA closure alone in patients with persistent and longstanding persistent AF undergoing mitral valve surgery. Nested within this trial, is a further randomized comparison of 2 different lesions sets: pulmonary vein isolation and full Maze lesion set. This paper addresses trial design challenges, including how to best characterize the target population, operationalize freedom from AF as a primary endpoint, account for the impact of anti-arrhythmic drugs, and measure and analyze secondary endpoints, such as post-operative AF load. Conclusions This paper concludes by discussing how insights that emerge from this trial may affect surgical practice and guide future research in this area. PMID:21616507

  2. Low Left Atrial Compliance Contributes to the Clinical Recurrence of Atrial Fibrillation after Catheter Ablation in Patients with Structurally and Functionally Normal Heart.

    PubMed

    Park, Junbeom; Yang, Pil-sung; Kim, Tae-Hoon; Uhm, Jae-Sun; Kim, Joung-Youn; Joung, Boyoung; Lee, Moon-Hyoung; Hwang, Chun; Pak, Hui-Nam

    2015-01-01

    Stiff left atrial (LA) syndrome was initially reported in post-cardiac surgery patients and known to be associated with low LA compliance. We investigated the physiological and clinical implications of LA compliance by estimating LA pulse pressure (LApp) among patients with atrial fibrillation (AF) and structurally and functionally normal heart. Among 1038 consecutive patients with LA pressure measurements before AF ablation, we included 334 patients with structurally and functionally normal heart (81.7% male, 54.1±10.6 years, 77.0% paroxysmal AF) after excluding those with hypertension, diabetes, and previous ablation or cardiac surgery. We measured LApp (peak-nadir LA pressure) at the beginning of the ablation procedure and compared the values with clinical parameters and the AF recurrence rate. AF patients with normal heart were younger and more frequently male and had paroxysmal AF, a lower body mass index, and a lower LApp compared to others (all p<0.05). Based on the median value, the low LA compliance group (LApp≥13 mmHg) had a smaller LA volume index and lower LA voltage (all p<0.05) compared to the high LA compliance group. During a mean follow-up of 16.7±11.8 months, low LA compliance was independently associated with two fold-higher risk of clinical AF recurrence (HR:2.202; 95%CI:1.077-4.503; p = 0.031). Low LA compliance, as determined by an elevated LApp, was associated with a smaller LA volume index and lower LA voltage and independently associated with higher clinical recurrence after catheter ablation in AF patients with structurally and functionally normal heart.

  3. Real-time circumferential mapping catheter tracking for motion compensation in atrial fibrillation ablation procedures

    NASA Astrophysics Data System (ADS)

    Brost, Alexander; Bourier, Felix; Wimmer, Andreas; Koch, Martin; Kiraly, Atilla; Liao, Rui; Kurzidim, Klaus; Hornegger, Joachim; Strobel, Norbert

    2012-02-01

    Atrial fibrillation (AFib) has been identified as a major cause of stroke. Radiofrequency catheter ablation has become an increasingly important treatment option, especially when drug therapy fails. Navigation under X-ray can be enhanced by using augmented fluoroscopy. It renders overlay images from pre-operative 3-D data sets which are then fused with X-ray images to provide more details about the underlying soft-tissue anatomy. Unfortunately, these fluoroscopic overlay images are compromised by respiratory and cardiac motion. Various methods to deal with motion have been proposed. To meet clinical demands, they have to be fast. Methods providing a processing frame rate of 3 frames-per-second (fps) are considered suitable for interventional electrophysiology catheter procedures if an acquisition frame rate of 2 fps is used. Unfortunately, when working at a processing rate of 3 fps, the delay until the actual motion compensated image can be displayed is about 300 ms. More recent algorithms can achieve frame rates of up to 20 fps, which reduces the lag to 50 ms. By using a novel approach involving a 3-D catheter model, catheter segmentation and a distance transform, we can speed up motion compensation to 25 fps which results in a display delay of only 40 ms on a standard workstation for medical applications. Our method uses a constrained 2-D/3-D registration to perform catheter tracking, and it obtained a 2-D tracking error of 0.61 mm.

  4. Panel flutter

    NASA Technical Reports Server (NTRS)

    Dowell, E. H.

    1972-01-01

    Criteria are presented for the prediction of panel flutter, determination of its occurrence, design for its prevention, and evaluation of its severity. Theoretical analyses recommended for the prediction of flutter stability boundaries, vibration amplitudes, and frequencies for several types of panels are described. Vibration tests and wind tunnel tests are recommended for certain panels and environmental flow conditions to provide information for design of verification analysis. Appropriate design margins on flutter stability boundaries are given and general criteria are presented for evaluating the severity of possible short-duration, limited-amplitude panel flutter on nonreusable vehicles.

  5. Association of SCN10A Polymorphisms with the Recurrence of Atrial Fibrillation after Catheter Ablation in a Chinese Han Population

    PubMed Central

    Wu, Haiqing; Xu, Juan; Chen, Songwen; Zhou, Genqing; Qi, Baozhen; Wei, Yong; Hu, En; Tang, Dongdong; Chen, Gang; Li, Hongli; Zhao, Liqun; Shi, Yongyong; Liu, Shaowen

    2017-01-01

    The nonsynonymous SCN10A single nucleotide polymorphism (SNP) rs6795970 has been reported to associate with PR interval and atrial fibrillation (AF) and in strong linkage disequilibrium (LD) with the AF-associated SNP rs6800541. In this study, we investigated whether rs6795970 polymorphisms are associated with AF recurrence after catheter ablation. A total of 502 consecutive patients with AF who underwent catheter ablation were included. AF recurrence was defined as a documented episode of any atrial arrhythmias lasting ≥30 s after a blanking period of 3 months. AF recurrence was observed between 3 and 12 months after catheter ablation in 24.5% of the patients. There was a significant difference in the allele distribution (p = 7.86 × 10−5) and genotype distribution (p = 1.42 × 10−5) of rs6795970 between the AF recurrence and no recurrence groups. In a multivariate analysis, we identified the following independent predictors of AF recurrence: the rs6795970 genotypes in an additive model (OR 0.36, 95%CI 0.22~0.60, p = 7.04 × 10−5), a history of AF ≥36 months (OR 3.57, 95%CI 2.26~5.63, p = 4.33 × 10−8) and left atrial diameter (LAD) ≥40 mm (OR 1.85, 95%CI 1.08~3.19, p = 0.026). These data suggest that genetic variation in SCN10A may play an important role in predicting AF recurrence after catheter ablation in the Chinese Han population. PMID:28281580

  6. Association of SCN10A Polymorphisms with the Recurrence of Atrial Fibrillation after Catheter Ablation in a Chinese Han Population.

    PubMed

    Wu, Haiqing; Xu, Juan; Chen, Songwen; Zhou, Genqing; Qi, Baozhen; Wei, Yong; Hu, En; Tang, Dongdong; Chen, Gang; Li, Hongli; Zhao, Liqun; Shi, Yongyong; Liu, Shaowen

    2017-03-10

    The nonsynonymous SCN10A single nucleotide polymorphism (SNP) rs6795970 has been reported to associate with PR interval and atrial fibrillation (AF) and in strong linkage disequilibrium (LD) with the AF-associated SNP rs6800541. In this study, we investigated whether rs6795970 polymorphisms are associated with AF recurrence after catheter ablation. A total of 502 consecutive patients with AF who underwent catheter ablation were included. AF recurrence was defined as a documented episode of any atrial arrhythmias lasting ≥30 s after a blanking period of 3 months. AF recurrence was observed between 3 and 12 months after catheter ablation in 24.5% of the patients. There was a significant difference in the allele distribution (p = 7.86 × 10(-5)) and genotype distribution (p = 1.42 × 10(-5)) of rs6795970 between the AF recurrence and no recurrence groups. In a multivariate analysis, we identified the following independent predictors of AF recurrence: the rs6795970 genotypes in an additive model (OR 0.36, 95%CI 0.22~0.60, p = 7.04 × 10(-5)), a history of AF ≥36 months (OR 3.57, 95%CI 2.26~5.63, p = 4.33 × 10(-8)) and left atrial diameter (LAD) ≥40 mm (OR 1.85, 95%CI 1.08~3.19, p = 0.026). These data suggest that genetic variation in SCN10A may play an important role in predicting AF recurrence after catheter ablation in the Chinese Han population.

  7. [Catheter ablation of atrial fibrillation: Health Technology Assessment Report from the Italian Association of Arrhythmology and Cardiac Pacing (AIAC)].

    PubMed

    Themistoclakis, Sakis; Tritto, Massimo; Bertaglia, Emanuele; Berto, Patrizia; Bongiorni, Maria Grazia; Catanzariti, Domenico; De Fabrizio, Giuseppe; De Ponti, Roberto; Grimaldi, Massimo; Pandozi, Claudio; Tondo, Claudio; Gulizia, Michele

    2011-11-01

    Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and significantly impact patients' quality of life, morbidity and mortality. The number of affected patients is expected to increase as well as the costs associated with AF management, mainly driven by hospitalizations. Over the last decade, catheter ablation techniques targeting pulmonary vein isolation have demonstrated to be effective in treating AF and preventing AF recurrence. This Health Technology Assessment report of the Italian Association of Arrhythmology and Cardiac Pacing (AIAC) aims to define the current role of catheter ablation of AF in terms of effectiveness, efficiency and appropriateness. On the basis of an extensive review of the available literature, this report provides (i) an overview of the epidemiology, clinical impact and socio-economic burden of AF; (ii) an evaluation of therapeutic options other than catheter ablation of AF; and (iii) a detailed presentation of clinical outcomes and cost-benefit ratio associated with catheter ablation. The costs of catheter ablation of AF in Italy were obtained using a bottom-up analysis of a resource utilization survey of 52 hospitals that were considered a representative sample, including 4 Centers that contributed with additional unit cost information in a separate questionnaire. An analysis of budget impact was also performed to evaluate the impact of ablation on the management costs of AF. Results of this analysis show that (1) catheter ablation is effective, safe and superior to antiarrhythmic drug therapy in maintaining sinus rhythm; (2) the cost of an ablation procedure in Italy typically ranges from €8868 to €9455, though current reimbursement remains insufficient, covering only about 60% of the costs; (3) the costs of follow-up are modest (about 8% of total costs); (4) assuming an adjustment of reimbursement to the real cost of an ablation procedure and a 5-10% increase in the annual rate of ablation procedures, after

  8. Entropy at the right atrium as a predictor of atrial fibrillation recurrence outcome after pulmonary vein ablation.

    PubMed

    Cervigón, Raquel; Moreno, Javier; García-Quintanilla, Jorge; Pérez-Villacastín, Julián; Castells, Francisco

    2016-02-01

    Atrial fibrillation (AF) recurrence rates after successful ablation procedures are still high and difficult to predict. This work studies the capability of entropy measured from intracardiac recordings as an indicator for recurrence outcome. Intra-atrial recordings from 31 AF patients were registered previously to an ablation procedure. Four electrodes were located at the right atrium (RA) and four more at the left atrium (LA). Sample entropy measurements were applied to these signals, in order to characterize different non-linear AF dynamics at the RA and LA independently. In a 3 months follow-up, 19 of them remained in sinus rhythm, whereas the other 12 turned back to AF. Entropy values can be associated to a proarrhythmic indicator as they were higher in patients with AF recurrence (1.11±0.15 vs. 0.91±0.13), in persistent patients (1.03±0.19 vs. 0.96±0.15), and at the LA with respect to the RA (1.03±0.23 vs. 0.89±0.15 for paroxysmal AF patients). Furthermore, entropy values at the RA arose as a more reliable predictor for recurrence outcome than at the LA. Results suggest that high entropy values, especially at the RA, are associated with high risk of AF recurrence. These findings show the potential of the proposed method to predict recurrences post-ablation, providing additional insights to the understanding of arrhythmia.

  9. Alternative energy sources for surgical treatment of atrial fibrillation in patients undergoing mitral valve surgery: microwave ablation vs cryoablation.

    PubMed

    Kim, Joon Bum; Cho, Won-Chul; Jung, Sung Ho; Chung, Cheol Hyun; Choo, Suk Jung; Lee, Jae Won

    2010-10-01

    The study aim was to compare maze outcomes using microwave ablation or cryoablation in patients with mitral disease and atrial fibrillation (AF). Between 1999 and 2005, 340 patients underwent mitral valve surgery and concomitant maze procedure involving either microwave ablation (n=96, MW group) or cryoablation (n=244, Cryo group). Mean age at operation was 50.0±12.5 yr. Follow-up period was 46.1±28.2 months. The Cryo group showed a longer aortic clamping time than the MW group (P=0.005). There were no differences in operative mortality and morbidity rates. The unadjusted 5-yr AF free rate was 61.3±1.2% in the MW group and 79.9±3.2% in the Cryo group (P=0.089). After adjustment, the MW group only showed a tendency toward more frequent AF recurrence than the Cryo group (Hazard ration 1.66, 95% confidence interval 0.89 to 3.07). Multivariate analysis revealed that older patient age (P<0.001) and greater left atrial size (P<0.001) were independent risk factors for AF recurrence. Although the use of microwave ablation results in shorter aortic clamping time, it has a tendency toward more frequent late AF recurrence than with cryoablation.

  10. Peri-procedural interrupted oral anticoagulation for atrial fibrillation ablation: comparison of aspirin, warfarin, dabigatran, and rivaroxaban

    PubMed Central

    Winkle, Roger A.; Mead, R. Hardwin; Engel, Gregory; Kong, Melissa H.; Patrawala, Rob A.

    2014-01-01

    Aims Atrial fibrillation ablation requires peri-procedural oral anticoagulation (OAC) to prevent thromboembolic events. There are several options for OAC. We evaluate peri-procedural AF ablation complications using a variety of peri-procedural OACs. Methods and results We examined peri-procedural OAC and groin, bleeding, and thromboembolic complications for 2334 consecutive AF ablations using open irrigated-tip radiofrequency (RF) catheters. Pre-ablation OAC was warfarin in 1113 (47.7%), dabigatran 426 (18.3%), rivaroxaban 187 (8.0%), aspirin 472 (20.2%), and none 136 (5.8%). Oral anticoagulation was always interrupted and intraprocedural anticoagulation was unfractionated heparin (activated clotting time, ACT = 237 ± 26 s). Pre- and post-OAC drugs were the same for 1591 (68.2%) and were different for 743 (31.8%). Following ablation, 693 (29.7%) were treated with dabigatran and 291 (12.5%) were treated with rivaroxaban. There were no problems changing from one OAC pre-ablation to another post-ablation. Complications included 12 (0.51%) pericardial tamponades [no differences for dabigatran (P = 0.457) or rivaroxaban (P = 0.163) compared with warfarin], 12 (0.51%) groin complications [no differences for rivaroxaban (P = 0.709) and fewer for dabigatran (P = 0.041) compared with warfarin]. Only 5 of 2334 (0.21%) required blood transfusions. There were two strokes (0.086%) and no transient ischaemic attacks (TIAs) in the first 48 h post-ablation. Three additional strokes (0.13%), and two TIAs (0.086%) occurred from 48 h to 30 days. Only one stroke had a residual deficit. Compared with warfarin, the neurologic event rate was not different for dabigatran (P = 0.684) or rivaroxaban (P = 0.612). Conclusion Using interrupted OAC, low target intraprocedural ACT, and irrigated-tip RF, the rate of peri-procedural groin, haemorrhagic, and thromboembolic complications was extremely low. There were only minimal differences between OACs. Low-risk patients may remain on aspirin

  11. Effect of sequential radiofrequency ablation lesions at fast and slow atrioventricular nodal pathway positions in patients with paroxysmal atrial fibrillation.

    PubMed Central

    Garratt, C. J.; Skehan, J. D.; Payne, G. E.; Stafford, P. J.

    1996-01-01

    OBJECTIVE: To examine the hypothesis that the anatomic equivalents of the fast and slow pathways identified in patients with atrioventricular (AV) nodal tachycardia may be universal and represent the principal sites of atrial input into the normal compact AV node. METHODS: 15 patients undergoing complete AV junction ablation for paroxysmal atrial fibrillation were studied. Radiofrequency energy was delivered first in the anterior "fast pathway" position so as to prolong the atrium to bundle of His (AH) interval by over 50% of baseline (protocol 1) and then to the "slow pathway" position using the anatomical technique (protocol 2). RESULTS: Ablation protocol 1 resulted in prolongation of AH interval in all patients. Subsequent lesions at the level of the coronary sinus produced complete heart block in four patients, and in five caused a further increase in AH interval above that produced by protocol 1. Four of these latter patients developed complete block after delivery of RF energy slightly anterior to the level of the coronary sinus os, as did three further patients in whom ablation at the level of the coronary sinus had no effect. In four patients complete heart block could not be achieved by protocol 2. CONCLUSIONS: A discrete anterior "fast" pathway and a posterior "slow" pathway or network of posterior pathways form the principal inputs to the compact AV node in most patients with atrial fibrillation. The absence of dual AV nodal physiology in the majority of these patients may be related to the functional properties of the individual components of this posterior network. PMID:8665345

  12. Impact of metabolic syndrome on the risk of atrial fibrillation recurrence after catheter ablation: systematic review and meta-analysis

    PubMed Central

    Lin, Kueiyu Joshua; Cho, Soung Ick; Tiwari, Nidhish; Bergman, Michael; Kizer, Jorge R.; Palma, Eugen C.; Taub, Cynthia C.

    2015-01-01

    Purpose The impact of metabolic syndrome (MetS) on recurrence of atrial fibrillation (AF) after catheter ablation remains uncertain. We conducted a meta-analysis to summarize the relative risks (RR) of AF recurrence after catheter ablation in patients with vs. without MetS and its components. Methods Among 839 articles identified from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials, we included 23 studies with a total of 12,924 patients (7,594 with paroxysmal AF and 5,330 with nonparoxysmal AF) for analysis. Five of these had complete information on MetS components. Variables assessed comprised study design and population characteristics, AF ablation methods, use of anti-arrhythmic drugs, AF recurrence ascertainment methods, adjustment variables, and other quality indicators. Results Our meta-analysis found an elevated risk of AF recurrence after ablation in patients with vs. without MetS (pooled RR, 1.63; 95 % confidence interval (CI), 1.25–2.12). Among components of MetS, hypertension was a predictor of AF post-ablation recurrence in studies without adjustment for other MetS components (RR, 1.62; 95 % CI, 1.23–2.13) but not in those adjusting for two or more additional MetS components (RR, 1.03; 95 % CI, 0.88–1.20). There was a borderline association between overweight/obesity and AF recurrence after ablation (RR, 1.27; 95 % CI, 0.99–1.64). Conclusions MetS is associated with an increased risk of AF recurrence after catheter ablation. Further study of the MetS and its components as determinants of AF risk could help refine patient selection and improve procedural outcomes. PMID:24346619

  13. Atrial fibrillation in endurance athletes.

    PubMed

    Wilhelm, Matthias

    2014-08-01

    There is a growing population of veteran endurance athletes, regularly participating in training and competition. Although the graded benefit of exercise on cardiovascular health and mortality is well established, recent studies have raised concern that prolonged and strenuous endurance exercise may predispose to atrial and ventricular arrhythmias. Atrial fibrillation (AF) and atrial flutter are facilitated by atrial remodelling, atrial ectopy, and an imbalance of the autonomic nervous system. Endurance sports practice has an impact on all of these factors and may therefore act as a promoter of these arrhythmias. In an animal model, long-term intensive exercise training induced fibrosis in both atria and increased susceptibility to AF. While the prevalence of AF is low in young competitive athletes, it increases substantially in the aging athlete, which is possibly associated with an accumulation of lifetime training hours and participation in competitions. A recent meta-analysis revealed a 5-fold increased risk of AF in middle-aged endurance athletes with a striking male predominance. Beside physical activity, height and absolute left atrial size are independent risk factors for lone AF and the stature of men per se may explain part of their higher risk of AF. Furthermore, for a comparable amount of training volume and performance, male non-elite athletes exhibit a higher blood pressure at rest and peak exercise, a more concentric type of left ventricular remodelling, and an altered diastolic function, possibly contributing to a more pronounced atrial remodelling. The sports cardiologist should be aware of the distinctive features of AF in athletes. Therapeutic recommendations should be given in close cooperation with an electrophysiologist. Reduction of training volume is often not desired and drug therapy not well tolerated. An early ablation strategy may be appropriate for some athletes with an impaired physical performance, especially when continuation of

  14. Intrinsic Cardiac Autonomic Ganglionated Plexi within Epicardial Fats Modulate the Atrial Substrate Remodeling: Experiences with Atrial Fibrillation Patients Receiving Catheter Ablation

    PubMed Central

    Singhal, Rahul; Lo, Li-Wei; Lin, Yenn-Jiang Lin; Chang, Shih-Lin; Hu, Yu-Feng; Chao, Tze-Fan; Chung, Fa-Po; Chiou, Cheun-Wang; Tsao, Hsuan-Ming; Chen, Shih-Ann

    2016-01-01

    Background A recent study reported the close relationship between high dominant frequent (DF) sites [atrial fibrillation (AF) nest] and the intrinsic cardiac autonomic nervous system. The aim of this study was to investigate the correlation between the regional distribution of epicardial fat and the properties of the biatrial substrates in AF patients. Methods We studied 32 patients with paroxysmal (n = 23) and persistent (n = 9) AF. The epicardial fat volume around the left atrium (LA) was evaluated using 64-slice multidetector computed tomography and the topographic distribution of the fat volume was assessed. The biatrial DFs, voltages, and total activation times (TATs) were obtained during sinus rhythm. Results Out of the 8 divided LA regions, a significant linear correlation existed between the LA fat and mean DF values in the right upper anterior LA, left upper anterior LA, right lower anterior LA, right upper posterior LA, left upper posterior LA, and left lower posterior LA. There was no significant correlation between the regional LA fat distribution and regional LA peak-to-peak bipolar voltage and TAT. During a mean follow-up of 17 ± 8 months, 22 of the 32 (69%) patients were free of AF. In the multivariate analysis, only the mean LA DF was found to be a significant predictor of recurrence. Conclusions There was a close association between the regional distribution of the LA epicardial fat and the atrial substrate manifesting high frequency during sinus rhythm (AF nest). Those nests were related to ablation outcome. Hence, epicardial fat may play a significant role in atrial substrate remodeling and thereby in the pathogenesis and maintenance of AF. PMID:27122948

  15. Rivaroxaban for Periprocedural Anticoagulation Therapy in Japanese Patients Undergoing Catheter Ablation of Paroxysmal Non-Valvular Atrial Fibrillation.

    PubMed

    Kawabata, Mihoko; Sasaki, Takeshi; Maeda, Shingo; Shirai, Yasuhiro; Yamauchi, Yasuteru; Nitta, Junichi; Goya, Masahiko; Hirao, Kenzo

    2016-12-02

    Direct oral anticoagulants (DOACs) have been shown to be safe and effective for the prevention of stroke in nonvalvular atrial fibrillation (NVAF) patients, however, experience with peri-AF ablation management of DOACs is scarce. This study aimed to investigate the safety and feasibility of periprocedural anticoagulation therapy with rivaroxaban in Japanese patients undergoing paroxysmal non-valvular AF (NVAF) ablation using radiofrequency energy.This study was a multicenter, prospective pilot study. In paroxysmal NVAF patients, rivaroxaban (15 mg or 10 mg once-daily) was started at least 4 weeks prior to AF ablation, discontinued on the day of the procedure, resumed within 24 hours after ablation, and continued at least 3 months afterwards. During the interruption of rivaroxaban, bridging anticoagulation therapy with unfractionated heparin was given. Follow-up of the patients continued for 3 months.A total of consecutive 74 patients (mean age, 62 ± 9 years, 58 [78.4%] male) were enrolled. The mean follow-up period was 108 ± 79 days. Their mean CHADS2 score and CHA2DS2-VASc score were 1.2 ± 1.0 and 0.6 ± 0.7, respectively. Their mean HAS-BLED score was 1.0 ± 0.8. Neither major bleeding nor thromboembolic events, except in a case with bleeding from gastric cancer (1.4%), were observed in the periprocedural period of the AF ablation.The present multicenter study demonstrated the safety and feasibility of periprocedural anticoagulation therapy with rivaroxaban in Japanese patients undergoing catheter ablation of paroxysmal NVAF.

  16. Surgical ablation of atrial fibrillation: a protocol for a systematic review and meta-analysis of randomised controlled trials

    PubMed Central

    McClure, Graham R; Belley-Cote, Emilie P; Singal, Rohit K; Jaffer, Iqbal H; Dvirnik, Nazari; An, Kevin R; Fortin, Gabriel; Spence, Jessica; Whitlock, Richard P

    2016-01-01

    Introduction Atrial fibrillation (AF) affects 10% of patients undergoing cardiac surgery and is an independent risk factor for all-cause mortality, ischaemic stroke and heart failure. Surgical AF ablation has been shown to significantly improve maintenance of sinus rhythm, however, small to medium size trials conducted to date lack the power required to assess patient-important outcomes such as mortality, stroke, heart failure and health-related quality of life. Moreover, a recent randomised trial (RCT) suggested harm by surgical AF ablation with an almost threefold increase in the requirement for permanent pacemaker postablation. We aim to perform a systematic review and meta-analysis to evaluate efficacy and safety of surgical AF ablation compared to no surgical ablation. Methods and analysis We will search Cochrane CENTRAL, MEDLINE and EMBASE for RCTs evaluating the use of surgical AF ablation, including any lesion set, versus no surgical AF ablation in adults with AF undergoing any type of cardiac surgery. Outcomes of interest include mortality, embolic events, quality of life, rehospitalisation, freedom from AF and adverse events, including need for pacemaker and worsening heart failure. Independently and in duplicate, reviewers will screen references, assess eligibility of potentially relevant studies using predefined eligibility criteria and collect data using prepiloted forms. We will pool data using a random effects model and present results as relative risk with 95% CIs for dichotomous outcomes and as mean difference with 95% CI for continuous outcomes. We will assess risk of bias using the Cochrane Collaboration tool, and quality of evidence with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Ethics and dissemination Our results will help guide clinical practice by providing the most comprehensive analysis of risks and benefits associated with the procedure. Our results will be disseminated through publication in

  17. Novel Radiofrequency Ablation Strategies for Terminating Atrial Fibrillation in the Left Atrium: A Simulation Study

    PubMed Central

    Bayer, Jason D.; Roney, Caroline H.; Pashaei, Ali; Jaïs, Pierre; Vigmond, Edward J.

    2016-01-01

    Pulmonary vein isolation (PVI) with radiofrequency ablation (RFA) is the cornerstone of atrial fibrillation (AF) therapy, but few strategies exist for when it fails. To guide RFA, phase singularity (PS) mapping locates reentrant electrical waves (rotors) that perpetuate AF. The goal of this study was to test existing and develop new RFA strategies for terminating rotors identified with PS mapping. It is unsafe to test experimental RFA strategies in patients, so they were evaluated in silico using a bilayer computer model of the human atria with persistent AF (pAF) electrical (ionic) and structural (fibrosis) remodeling. pAF was initiated by rapidly pacing the right (RSPV) and left (LSPV) superior pulmonary veins during sinus rhythm, and rotor dynamics quantified by PS analysis. Three RFA strategies were studied: (i) PVI, roof, and mitral lines; (ii) circles, perforated circles, lines, and crosses 0.5–1.5 cm in diameter/length administered near rotor locations/pathways identified by PS mapping; and (iii) 4–8 lines streamlining the sequence of electrical activation during sinus rhythm. As in pAF patients, 2 ± 1 rotors with cycle length 185 ± 4 ms and short PS duration 452 ± 401 ms perpetuated simulated pAF. Spatially, PS density had weak to moderate positive correlations with fibrosis density (RSPV: r = 0.38, p = 0.35, LSPV: r = 0.77, p = 0.02). RFA PVI, mitral, and roof lines failed to terminate pAF, but RFA perforated circles and lines 1.5 cm in diameter/length terminated meandering rotors from RSPV pacing when placed at locations with high PS density. Similarly, RFA circles, perforated circles, and crosses 1.5 cm in diameter/length terminated stationary rotors from LSPV pacing. The most effective strategy for terminating pAF was to streamline the sequence of activation during sinus rhythm with >4 RFA lines. These results demonstrate that co-localizing 1.5 cm RFA lesions with locations of high PS density is a promising strategy for terminating pAF rotors

  18. Safety and Efficacy of Underdosing Non-vitamin K Antagonist Oral Anticoagulants in Patients Undergoing Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Murakami, Takashi; Hina, Kazuyoshi; Higashiya, Shunichi; Kawamura, Hiroshi; Murakami, Masaaki; Kamikawa, Shigeshi; Komatsubara, Issei; Kusachi, Shozo

    2017-01-01

    Background: Some patients with atrial fibrillation (AF) received underdoses of non-vitamin K antagonist oral anticoagulants (NOACs) in the real world. Underdosing is defined as administration of a dose lower than the manufacturer recommended dose. Objectives: To identify the efficacy and safety of underdosing NOACs as perioperative anticoagulation for atrial fibrillation ablation. Methods: We retrospectively analyzed patients who received rivaroxaban or dabigatran etexilate according to dosage: adjusted low dosage (reduced by disturbed renal function; n = 30), underdosage (n = 307), or standard dosage (n = 683). Non-vitamin K antagonist oral anticoagulants and dosing decisions were at the discretion of treating cardiologists. Results: Patients who received underdosed NOACs were older, more often female, and had lower body weight and lower renal function than those who received standard dosages. Activated clotting time at baseline in patients who received adjusted low dosage or underdosages was slightly longer than that in patients receiving standard dosages (156 ± 23, 151 ± 224, and 147 ± 24 seconds, respectively). Meaningful differences were not observed in other coagulation parameters. Adjusted low-, under-, and standard-dosing regimens did not differ in perioperative thromboembolic complications (0/30, 0.0%; 1/307, 0.3%; and 0/683, 0%, respectively) or major (0/30, 0.0%; 2/307, 0.6%; 3/683, 0.4%) and minor (1/30, 3.3%; 13/307, 4.2%; 25/683, 3.6%) bleeding episodes. When comparisons were performed for each NOAC, similar results were observed. Conclusions: With consideration of patient condition, age, sex, body weight, body mass index, and renal function, underdosing NOACs was effective and safe as a perioperative anticoagulation therapy for atrial fibrillation ablation. The therapeutic range of NOACs is potentially wider than manufacturer recommendations. PMID:28170360

  19. [Endocavitary ablation for arrhythmias. New modalities of radiofrequency applications. New energy types].

    PubMed

    Cauchemez, B; Lavergne, Th; Extramiana, F; Siliste, C; Leenhardt, A; Coumel, Ph

    2002-04-01

    Radiofrequency remains the reference energy type for catheter ablation of rhythm disorders. In the classic indications, which are atrial flutter or tachycardia, nodal re-entry and Wolff-Parkinson-White syndrome, this energy source has the best cost-efficiency-safety ratio, subject to strict conditions of use. Some new modalities of application have further improved performance, especially active irrigation of the electrode which allows induction of deeper lesions which is very useful for the ablation of difficult atrial flutters, epicardial fascicles of Kent and ischaemic ventricular tachycardias. The only emerging alternative energy type, in the framework of classical ablation, is cold, for which the principal advantages are the homogenous and slightly thrombogenic character for the lesion involved, and the possibility of reversible applications tests which are especially useful in the ablation of structures at risk. The situation is more open-ended concerning research on ablation for atrial fibrillation or the so-called new energy types, such as ultrasound and laser, whilst recognising a renewal in interest, especially for circumferential ablation of the pulmonary veins to isolate the ectopic venous foci. Mechanical energy such as luminous energy is emitted across a catheter balloon deployed at the orifice of the vein, perpendicular to its axis, aiming to reach a continuous circumferential lesion with a minimum of applications. Equally radiofrequency has been undergoing significant evolution for this application, such as by the development of porous catheter balloons with a liquid electrode, as well as by the development of deployable circumferential catheters. Ablation is use for atrial fibrillation, by endocavity atrial segmentation remains a field of research in which radiofrequency retains an important place. It is delivered via multi-electrode catheters according to the new application modalities, either pulsed or by phase interval, which secure better

  20. Simple Method of Counterclockwise Isthmus Conduction Block by Comparing Double Potentials and Flutter Cycle Length

    PubMed Central

    Rhee, Kyoung-Suk; Kwon, Keun-Sang; Lee, Sun Hwa; Lee, Kang-Hyu; Lee, Sang Rok; Chae, Jei Keon; Kim, Won-Ho; Ko, Jae-Ki; Nam, Gi-Byoung; Kim, You-Ho

    2009-01-01

    Background and Objectives Local wide split double potentials are used as a parameter to determine complete conduction block during cavotricuspid isthmus ablation in patients with isthmus dependent atrial flutter. However, delayed slow conduction in that region can sometimes be very difficult to differentiate from complete block. Flutter cycle length (FCL) can be used to confirm isthmus conduction block, because FCL is a measure of conduction time around the tricuspid annulus (TA). This study was designed to determine which degree of splitting of the local electrograms is adequate to confirm complete isthmus block, using FCL as a reference. Subjects and Methods Cavotricuspid isthmus (CTI) ablation was performed in fifty consecutive patients. The interval between the pacing stimulus on the lateral side of the CTI and the first component of the double potentials on the block line (SD1) corresponded to the counterclockwise conduction time. The interval between the pacing stimulus and second component (SD2) represented the clockwise conduction time to the contralateral side of the ablation line. SD1 and SD2 were measured before and after complete isthmus block. Results An SD1+SD2 reaching 90% of the FCL identified the counterclockwise isthmus conduction block with 94% sensitivity and 100% specificity. Conclusion If the sum of SD1 and SD2 following isthmus ablation was close to the FCL, complete conduction block was predicted with high diagnostic accuracy and positive predictive value for at least counterclockwise conduction. PMID:20049138

  1. Morphology and pathophysiology of target anatomical sites for ablation procedures in patients with atrial fibrillation: part II: pulmonary veins, caval veins, ganglionated plexi, and ligament of Marshall.

    PubMed

    Corradi, Domenico; Callegari, Sergio; Gelsomino, Sandro; Lorusso, Roberto; Macchi, Emilio

    2013-10-03

    The inadequate long-term efficacy of anti-arrhythmic therapy has been one of the main reasons for the development of non-pharmacological interventions for patients with atrial fibrillation such as catheter and surgical ablation. This has greatly increased interest in the functional morphology and electrophysiological properties of the atria and related anatomical structures. This article is the second of a two-part review that aims to provide anatomical and functional details concerning some of the principal anatomical sites commonly targeted by ablative procedures for treating atrial fibrillation, and covers pulmonary veins, ganglionated plexi, caval veins, and the ligament of Marshall. It also provides some general information about site-specific ablation procedures.

  2. Influence of the concomitant use of heparin on the effects of warfarin during catheter ablation for atrial fibrillation.

    PubMed

    Inada, Keiichi; Matsuo, Seiichiro; Tokutake, Ken-Ichi; Yokoyama, Ken-Ichi; Hioki, Mika; Narui, Ryohsuke; Ito, Keiichi; Tanigawa, Shin-Ichi; Yamashita, Seigo; Tokuda, Michifumi; Shibayama, Kenri; Miyanaga, Satoru; Sugimoto, Ken-Ichi; Yoshimura, Michihiro; Yamane, Teiichi

    2016-03-01

    Warfarin is widely used to perform catheter ablation for atrial fibrillation (AF). Heparin is usually administered during this procedure to prevent thromboembolic events, while protamine is used to reduce the incidence of bleeding complications. The purpose of this study was to investigate the influence of heparin and protamine administration on the effects of warfarin and its safety. The subjects included 226 AF patients (206 males, 54.9 ± 9.1 years, paroxysmal/persistent AF: 118/108) undergoing AF ablation with the discontinuation of warfarin administration over 2 days. Heparin was administered to achieve an activated clotting time (ACT) above 300 s during the procedure. Several parameters of the coagulation status, including the prothrombin time international normalized ratio (PT-INR) and ACT values, measured immediately before and after protamine infusion were compared. The mean value of PT-INR prior to ablation was 1.9 ± 0.6. At the end of the procedure, the mean ACT and PT-INR values were 348.0 ± 52.9 and 2.9 ± 0.7, respectively. Following the infusion of 30 mg of protamine, both the ACT and PT-INR values significantly decreased, to 159.6 ± 31.0 (p < 0.0001) and 1.6 ± 0.3 (p < 0.0001), respectively. No cases of symptomatic cerebral infarction were observed, although femoral hematomas developed in 17 (7.5 %) of the patients without further consequence. The concomitant use of heparin augments the effect of warfarin. Meanwhile, protamine administration immediately reverses both the ACT and PT-INR, indicating the applicability of protamine for AF ablation in patients under the mixed administration of heparin and warfarin.

  3. Near-infrared spectroscopy integrated catheter for characterization of myocardial tissues: preliminary demonstrations to radiofrequency ablation therapy for atrial fibrillation

    PubMed Central

    Singh-Moon, Rajinder P.; Marboe, Charles C.; Hendon, Christine P.

    2015-01-01

    Effects of radiofrequency ablation (RFA) treatment of atrial fibrillation can be limited by the ability to characterize the tissue in contact. Parameters obtained by conventional catheters, such as impedance and temperature can be insufficient in providing physiological information pertaining to effective treatment. In this report, we present a near-infrared spectroscopy (NIRS)-integrated catheter capable of extracting tissue optical properties. Validation experiments were first performed in tissue phantoms with known optical properties. We then apply the technique for characterization of myocardial tissues in swine and human hearts, ex vivo. Additionally, we demonstrate the recovery of critical parameters relevant to RFA therapy including contact verification, and lesion transmurality. These findings support the application of NIRS for improved guidance in RFA therapeutic interventions. PMID:26203376

  4. Differences in Quality of Life Between Atrial Fibrillation Patients with Low Stroke Risk Treated With and Without Catheter Ablation

    PubMed Central

    Bai, Ying; Bai, Rong; Wu, Jia-Hui; Zhang, Ting; Liu, Nian; Shi, Xu-Bo; Liu, Xin-Yao; Liu, Xiao-Hui; Du, Xin; Dong, Jian-Zeng; Ma, Chang-Sheng

    2015-01-01

    Background Impacts of a single radiofrequency ablation (RFA) on quality of life (QoL) were not well investigated in atrial fibrillation (AF) patients with low stroke risk. Methods and Results Nine hundred AF patients with low CHADS2 score (ie, CHADS2 ≤1) who completed both a baseline and 6-month Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire were selected from The Chinese Atrial Fibrillation Registry between 2011 and 2013. A final cohort of 222 patients was constructed after a propensity score matching with 74 in the RFA group and 148 in the non-RFA group. Domains of AFEQT were balanced at baseline between the 2 groups. No statistically significant differences were noted in QoL (all P>0.05) when AFEQT at 6 months was compared between groups, except for the symptoms domain (83.07±12.37 units in the RFA group vs. 77.68±17.14 units in the non-RFA group; P=0.008) and treatment satisfaction domain (76.34±14.92 units in the RFA group vs. 70.38±16.81 units in the non-RFA group; P=0.01). Within-group changes in all domains and the global score of the questionnaire were moderate to large, whereas between-group comparisons in baseline to 6-month changes and QoL at 6 months were small to moderate according to Cohen effect sizes. Conclusions QoL was balanced at baseline and improved at 6 months in both groups from this observational propensity-matched cohort based on the AFEQT questionnaire. However, RFA treatment was only associated with small-to-moderate superiorities over non-RFA treatment. The role of RFA in QoL improvement among AF patients with low stroke risk requires further research. PMID:26376990

  5. Efficacy and effects on cardiac function of radiofrequency catheter ablation vs. direct current cardioversion of persistent atrial fibrillation with left ventricular systolic dysfunction

    PubMed Central

    Wang, Maojing; Cai, Shanglang; Ding, Wei; Deng, Yujie; Zhao, Qing

    2017-01-01

    Objective To evaluate the effect of catheter ablation vs. direct current synchronized cardioversion (DCC) in patients with persistent atrial fibrillation (AF) and left ventricular systolic dysfunction, and to define baseline features of patients that will get more benefit from ablation. Methods From July 2013 to October 2014, 97 consecutive single-center patients with persistent AF and symptomatic heart failure (left ventricular ejection fraction (LVEF) <50%) underwent DCC followed by amiodarone (n = 40) or circumferential pulmonary vein isolation (PVI; n = 57) according to patient’s preference were recruited in the study. Post-ablation recurrence was treated with atrial roof and mitral isthmus lines ablation with or without PVI based on restoration or not of pulmonary vein (PV) potential conduction. Study outcomes were 12-month rate of sustained sinus rhythm (SR) and cardiac function. Baseline characteristics were compared between patients with and without cardiac function improvement post ablation. Results With similarly distributed characteristics at baseline, ablation (mean 1.8 procedures) relative to DCC yielded significantly higher level of 12-month SR maintenance rate (68.42% vs. 35%, P = 0.001); and better LVEF and New York Heart Association class. with significant effect for DCC only in maintained SR cases. Post ablation LVEF increased (>20% or to over 55%) in 31 (54.39%) patients with worse baseline cardiac function and ventricular rate control. Conclusions Catheter ablation relative to cardioversion of persistent AF with symptomatic heart failure yielded better 12-month SR maintenance and cardiac function. Compared with non-responders, patients with improved LVEF post-ablation had poorer ventricular rate control and cardiac function at baseline, suggesting a significant component of tachycardia-induced cardiomyopathy in this group. PMID:28350861

  6. Genomic Contributors to Rhythm Outcome of Atrial Fibrillation Catheter Ablation – Pathway Enrichment Analysis of GWAS Data

    PubMed Central

    Ueberham, Laura; Dinov, Borislav; Sommer, Philipp; Arya, Arash; Hindricks, Gerhard; Bollmann, Andreas

    2016-01-01

    Background Left atrial enlargement and persistent atrial fibrillation (AF) are well-known predictors for arrhythmia recurrence after AF catheter ablation (LRAF). In this study, by using pathway enrichment analysis of GWAS data, we tested the hypothesis that genetic pathways associated with these phenotypes are also associated with LRAF. Methods Samples from 660 patients with paroxysmal (n = 370) or persistent AF (n = 290) undergoing de-novo AF catheter ablation were genotyped for ~1,000,000 SNPs. SNPs found to be significantly associated with left atrial diameter (LAD) or AF type were used for gene-based association tests in a systematic biological Knowledge-based mining system for Genome-wide Genetic studies (KGG). Associated genes were tested for pathway enrichment using WEB-based Gene SeT AnaLysis Toolkit (WebGestalt), the Gene Annotation Tool to Help Explain Relationships (GATHER) and the databases provided by Kyoto Encyclopedia of Genes and Genomes (KEGG). In a second step, the association of consistently enriched pathways and LRAF was tested. Results By using sequential 7-day Holter ECGs, LRAF between 3 and 12 months was observed in 48% and was associated with LAD (B = 1.801, 95% CI 0.760–2.841, p = 1.0E-3) and persistent AF (OR = 2.1; 95% CI 1.567–2.931, p = 2.0E-6). WebGestalt (adj. p = 2.7E-22) and GATHER (adj. p = 5.2E-3) identified the calcium signaling pathway (hsa04020) as the only consistently enriched pathway for LAD, while the extracellular matrix (ECM) -receptor interaction pathway (hsa04512) was the only consistently enriched pathway for AF type (adj. p = 2.1E-15 in WebGestalt; adj. p = 9.3E-4 in GATHER). Both calcium signaling (adj. p = 2.2E-17 in WebGestalt; adj. p = 2.9E-2 in GATHER) and ECM-receptor interaction (adj. p = 1.2E-10 in WebGestalt; adj. p = 2.9E-2 in GATHER) were significantly associated with LRAF. Conclusions Calcium signaling and ECM-receptor interaction pathways are associated with LAD and AF type and, in turn, with LRAF

  7. Impact of Cryoballoon Ablation in Hypertrophic Cardiomyopathy-related Heart Failure due to Paroxysmal Atrial Fibrillation. A Comparative Case Series

    PubMed Central

    Maagh, Petra; Plehn, Gunnar; Christoph, Arnd; Oernek, Ahmet; Meissner, Axel

    2016-01-01

    Background: Atrial fibrillation (AF) represents a turning point in hypertrophic cardiomyopathy (HCM). Pulmonary Vein Isolation (PVI) with Radiofrequency Catheter Ablation (RFCA) is accepted to be successful in restoring sinus rhythm (SR) in HCM patients. The efficacy of cryoballoon (CB) therapy in HCM patients has not been studied so far. Methods: 166 patients with AF underwent PVI with CB technology in our single center between 1/2012 and 12/2015. To evaluate the efficacy of the CB therapy in HCM patients, we compared their clinical outcome with those in “Non-HCM” AF patients in a 3 and 6 months follow-up. Results: Out of 166 AF patients (65.7% paroxysmal AF, PAF), 4 patients had HCM and PAF (young males < 50 years). During the blanking period, 26 patients (15.8%) suffered from AF recurrence (11.0% PAF), including all HCM patients. The 6 months follow up of “Non-HCM” AF patients showed acceptable results (80% stable SR), whereas the HCM patients remained AF. In Conclusion: Even if the CB provides advantages, the single device cannot be recommended in HCM patients because of early AF recurrences. Anyway, because of the specific hemodynamic changes in HCM patients with AF, ablation should be sought in an early state of its occurrence, then, however, preferably with RFCA. PMID:27647995

  8. Long-term outcomes after ablation of persistent atrial fibrillation: an observational study over 6 years

    PubMed Central

    El-Kadri, Moutaz; Haq, Iram; Das, Moloy; Modi, Simon; Snowdon, Richard; Hall, Mark; Waktare, Johan EP; Todd, Derick M; Gupta, Dhiraj

    2016-01-01

    Objectives To address the limited long-term outcome data for catheter ablation (CA) of persistent atrial fibrillation (PeAF), we analysed consecutive ablations performed at our centre from 1 January 2008 to 31 December 2010 and followed patients prospectively until January 2014. Methods Both arrhythmia recurrence and symptom relief were assessed. Follow-up data were collected from hospital records, supplemented by data from general practitioners and referring hospitals. At the end of the follow-up period, all patients were contacted by phone to determine their up-to-date clinical condition. Results 188 consecutive patients with PeAF (157 male, mean age 57.3±9.7 years, 20% with long-standing PeAF) underwent a mean of 1.75 procedures (range 1–4). Telephone follow-up was achieved for 77% of surviving patients. Over a mean follow-up of 46±16 months (range 4–72), 139 (75%) patients experienced arrhythmia recurrence after a single procedure and 90 (48%) after their final procedure. Median time to first recurrence was 210 days (range 91–1850). 71% of recurrences were within the first year following ablation and 91% within 2 years. At final follow-up, 82% of patients reported symptomatic improvement. 7 (2.3%) major complications occurred, and there was no procedure-related death or stroke. Conclusions CA for PeAF is safe with a low rate of complications. Over a follow-up period of up to 6 years, a large majority of patients experience significant symptomatic improvement but recurrence after the initial procedure is the norm rather than the exception. 2 years' follow-up is sufficient to observe 90% of AF recurrences, but recurrence can occur even after 5 years' remission. PMID:27547426

  9. Effect of Surgical Atrial Fibrillation Ablation at the Time of Cardiac Surgery on Risk of Postoperative Pacemaker Implantation.

    PubMed

    El-Chami, Mikhael F; Binongo, José Nilo G; Levy, Mathew; Merchant, Faisal M; Halkos, Michael; Thourani, Vinod; Lattouf, Omar; Guyton, Robert; Puskas, John; Leon, Angel R

    2015-07-01

    The aim of this study was to retrospectively investigate whether performing surgical atrial fibrillation (AF) ablation in conjunction with cardiac surgery (CS) increases the risk for postoperative permanent pacemaker (PPM) requirement. The 30-day risk for PPM requirement was analyzed in consecutive patients who underwent CS from January 2007 to August 27, 2013. Patients were divided into 3 groups: (1) those who underwent AF ablation concomitant with CS (AF ABL), (2) patients with any history of AF who underwent surgery who did not undergo ablation (AF NO ABL), and (3) those with no histories of AF who underwent surgery (NO AF). Logistic regression analysis was performed adjusting for age, gender, and surgery type. Of 13,453 CS patients, 353 (3%) were in the AF ABL group, 1,701 (12%) in the AF NO ABL group, and 11,399 (85%) in the NO AF group. A total of 7,651 patients (57%) underwent coronary artery bypass grafting, 4,384 (33%) underwent valve surgery, and 1,418 (10%) underwent coronary artery bypass grafting and valve surgery. The overall PPM risk was 1.6% (212 of 13,453); risk was 5.7% (20 of 353) in the AF ABL group, 3.1% (53 of 1,701) in the AF NO ABL group, and 1.2% (139 of 11,399) in the NO AF group. The unadjusted and adjusted odds of PPM were higher in the AF ABL and AF NO ABL groups than in the NO AF group (adjusted odds ratio [OR] 2.7, 95% confidence interval [CI] 1.7 to 4.4, and adjusted OR 1.7, 95% CI 1.2 to 2.4, respectively). The unadjusted OR comparing the AF ABL group and the AF NO ABL group was significant (unadjusted OR 1.9, 95% CI 1.9 to 3.2); however, the OR adjusted for surgery type, age, and gender showed a trend toward significance (adjusted OR 1.6, 95% CI 0.9 to 2.7). In conclusion, in this large cohort of patients who underwent CS, surgical AF ablation appeared to carry an increased risk for postoperative PPM implantation.

  10. Atrial rate and rhythm abnormalities in a patient with hyperkalemia.

    PubMed

    Rosman, Jonathan; Thiagarajah, Prashan; Schweitzer, Paul; Rachko, Maurice; Hanon, Sam

    2009-05-15

    A 67 year old man presented with a serum potassium of 7.7 mEq/L and slow atrial flutter with variable A-V block and peaked T waves. Initial treatment for hyperkalemia was followed by an increase in the atrial flutter rate to 300 beats per minute. After hemodialysis the rhythm converted to sinus.

  11. Safety and Efficacy of Switching Anticoagulation to Aspirin Three Months after Successful Radiofrequency Catheter Ablation of Atrial Fibrillation

    PubMed Central

    Uhm, Jae-Sun; Won, Hoyoun; Joung, Boyoung; Nam, Gi-Byoung; Choi, Kee-Joon; Lee, Moon-Hyoung; Kim, You-Ho

    2014-01-01

    Purpose Although current guidelines recommend continuing the same antithrombotic strategy regardless of rhythm control after radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF), anticoagulation has a risk of major bleeding. We evaluated the safety of switching warfarin to aspirin in patients with successful AF ablation. Materials and Methods Among 721 patients who underwent RFCA of AF, 608 patients (age, 57.3±10.9 years; 77.0% male, 75.5% paroxysmal AF) who had no evidence of AF recurrence at 3 months post-RFCA were included. We compared the thromboembolic and hemorrhagic events in patients for whom warfarin was switched to aspirin (ASA group; n=296) and patients who were kept on warfarin therapy (W group; n=312). Results There were no significant differences in CHA2DS2-VASc or HAS-BLED scores between the groups. In 30 patients in the ASA group and 37 patients in W group, AF recurred and warfarin was restarted or maintained during the 18.0±12.2 months of follow-up. There were no significant differences in thromboembolic (0.3% vs. 1.0%, p=0.342) and major bleeding incidences (0.7% vs. 0.6%, p=0.958) between ASA and W groups during the follow-up period. In the 259 patients with a CHA2DS2-VASc score ≥2, there were no significant differences in thromboembolism (0.8% and 2.2%, p=0.380) or major bleeding incidences (0.8% and 1.4%, p=0.640) between ASA and W groups. Conclusion Switching warfarin to aspirin 3 months after successful RFCA of AF could be as safe and efficacious as long-term anticoagulation even in patients with CHA2DS2-VASc score ≥2. However, strict rhythm monitoring cannot be overemphasized. PMID:25048480

  12. Atrial Arrhythmias in Astronauts - Summary of a NASA Summit

    NASA Technical Reports Server (NTRS)

    Barr, Yael R.; Watkins, Sharmila D.; Polk, J. D.

    2010-01-01

    Background and Problem Definition: To evaluate NASA s current standards and practices related to atrial arrhythmias in astronauts, Space Medicine s Advanced Projects Section at the Johnson Space Center was tasked with organizing a summit to discuss the approach to atrial arrhythmias in the astronaut cohort. Since 1959, 11 cases of atrial fibrillation, atrial flutter, or supraventricular tachycardia have been recorded among active corps crewmembers. Most of the cases were paroxysmal, although a few were sustained. While most of the affected crewmembers were asymptomatic, those slated for long-duration space flight underwent radiofrequency ablation treatment to prevent further episodes of the arrhythmia. The summit was convened to solicit expert opinion on screening, diagnosis, and treatment options, to identify gaps in knowledge, and to propose relevant research initiatives. Summit Meeting Objectives: The Atrial Arrhythmia Summit brought together a panel of six cardiologists, including nationally and internationally renowned leaders in cardiac electrophysiology, exercise physiology, and space flight cardiovascular physiology. The primary objectives of the summit discussions were to evaluate cases of atrial arrhythmia in the astronaut population, to understand the factors that may predispose an individual to this condition, to understand NASA s current capabilities for screening, diagnosis, and treatment, to discuss the risks associated with treatment of crewmembers assigned to long-duration missions or extravehicular activities, and to discuss recommendations for prevention or management of future cases. Summary of Recommendations: The summit panel s recommendations were grouped into seven categories: Epidemiology, Screening, Standards and Selection, Treatment of Atrial Fibrillation Manifesting Preflight, Atrial Fibrillation during Flight, Prevention of Atrial Fibrillation, and Future Research

  13. Toward modeling of radio-frequency ablation lesions for image-guided left atrial fibrillation therapy: model formulation and preliminary evaluation.

    PubMed

    Linte, Cristian A; Camp, Jon J; Holmes, David R; Rettmann, Maryam E; Packer, Douglas L; Robb, Richard A

    2013-01-01

    In the context of image-guided left atrial fibrillation therapy, relatively very little work has been done to consider the changes that occur in the tissue during ablation in order to monitor therapy delivery. Here we describe a technique to predict the lesion progression and monitor the radio-frequency energy delivery via a thermal ablation model that uses heat transfer principles to estimate the tissue temperature distribution and resulting lesion. A preliminary evaluation of the model was conducted in ex vivo skeletal beef muscle tissue while emulating a clinically relevant tissue ablation protocol. The predicted temperature distribution within the tissue was assessed against that measured directly using fiberoptic temperature probes and showed agreement within 5°C between the model-predicted and experimentally measured tissue temperatures at prescribed locations. We believe this technique is capable of providing reasonably accurate representations of the tissue response to radio-frequency energy delivery.

  14. Design and rationale of the PRAGUE-12 trial: a large, prospective, randomized, multicenter trial that compares cardiac surgery with left atrial surgical ablation with cardiac surgery without ablation in patients with coronary and/or valvular heart disease plus atrial fibrillation.

    PubMed

    Straka, Zbyněk; Budera, Petr; Osmančík, Pavel; Vaněk, Tomáš; Hulman, Michal; Smíd, Michal; Malý, Marek; Widimský, Petr

    2013-01-01

    Surgical ablation procedure can restore sinus rhythm (SR) in patients with atrial fibrillation (AF) undergoing cardiac surgery. However, it is not known whether it has any impact on clinical outcomes. There is a need for a randomized trial with long-term follow-up to study the outcome of surgical ablation in patients with coronary and/or valve disease and AF. Patients are prospectively enrolled and randomized either to group A (cardiac surgery with left atrial ablation) or group B (cardiac surgery alone). The primary efficacy outcome is the SR presence (without any AF episode) during a 24-hour electrocardiogram after 1 year. The primary safety outcome is the combined end point of death, myocardial infarction, stroke, and renal failure at 30 days. Long-term outcomes are a composite of total mortality, stroke, bleeding, and heart failure at 1 and 5 years. We finished the enrollment with a total of 224 patients from 3 centers in 2 countries in December 2011. Currently, the incomplete 1-year data are available, and the patients who enrolled first will have their 5-year visits shortly. PRAGUE-12 is the largest study to be conducted so far comparing cardiac surgery with surgical ablation of AF to cardiac surgery without ablation in an unselected population of patients who are operated on for coronary and/or valve disease. Its long-term results will lead to a better recognition of ablation's potential clinical benefits.

  15. [Prophylaxis of thromboembolism in atrial fibrillation: new oral anticoagulants and left atrial appendage closure].

    PubMed

    Zeus, Tobias; Kelm, Malte; Bode, Christoph

    2015-08-01

    Thrombo-embolic prophylaxis is a key element within the therapy of atrial fibrillation/atrial flutter. Besides new oral anticoagulants the concept of left atrial appendage occlusion has approved to be a good alternative option, especially in patients with increased risk of bleeding.

  16. Ablation of Myocardial Tissue With Nanosecond Pulsed Electric Fields

    PubMed Central

    Xie, Fei; Varghese, Frency; Pakhomov, Andrei G.; Semenov, Iurii; Xiao, Shu; Philpott, Jonathan; Zemlin, Christian

    2015-01-01

    Background Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs) can potentially overcome these limitations. Methods We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12). We repeatedly inserted two shock electrodes, spaced 2–4 mm apart, into the ventricles (through the entire wall) and applied nanosecond pulsed electric fields (nsPEF) (5–20 kV/cm, 350 ns duration, at varying pulse numbers and frequencies) to create linear lesions of 12–18 mm length. Hearts were stained either with tetrazolium chloride (TTC) or propidium iodide (PI) to determine the extent of ablation. Some stained lesions were sectioned to obtain the three-dimensional geometry of the ablated volume. Results In all animals (12/12), we were able to create nonconducting lesions with less than 2 seconds of nsPEF application per site and minimal heating (< 0.2°C) of the tissue. The geometry of the ablated volume was smoother and more uniform throughout the wall than typical for RF ablation. The width of the lesions could be controlled up to 6 mm via the electrode spacing and the shock parameters. Conclusions Ablation with nsPEFs is a promising alternative to radiofrequency (RF) ablation of AF. It may dramatically reduce procedure times and produce more consistent lesion thickness than RF ablation. PMID:26658139

  17. Automatic classification of scar tissue in late gadolinium enhancement cardiac MRI for the assessment of left-atrial wall injury after radiofrequency ablation

    NASA Astrophysics Data System (ADS)

    Perry, Daniel; Morris, Alan; Burgon, Nathan; McGann, Christopher; MacLeod, Robert; Cates, Joshua

    2012-03-01

    Radiofrequency ablation is a promising procedure for treating atrial fibrillation (AF) that relies on accurate lesion delivery in the left atrial (LA) wall for success. Late Gadolinium Enhancement MRI (LGE MRI) at three months post-ablation has proven effective for noninvasive assessment of the location and extent of scar formation, which are important factors for predicting patient outcome and planning of redo ablation procedures. We have developed an algorithm for automatic classification in LGE MRI of scar tissue in the LA wall and have evaluated accuracy and consistency compared to manual scar classifications by expert observers. Our approach clusters voxels based on normalized intensity and was chosen through a systematic comparison of the performance of multivariate clustering on many combinations of image texture. Algorithm performance was determined by overlap with ground truth, using multiple overlap measures, and the accuracy of the estimation of the total amount of scar in the LA. Ground truth was determined using the STAPLE algorithm, which produces a probabilistic estimate of the true scar classification from multiple expert manual segmentations. Evaluation of the ground truth data set was based on both inter- and intra-observer agreement, with variation among expert classifiers indicating the difficulty of scar classification for a given a dataset. Our proposed automatic scar classification algorithm performs well for both scar localization and estimation of scar volume: for ground truth datasets considered easy, variability from the ground truth was low; for those considered difficult, variability from ground truth was on par with the variability across experts.

  18. Automatic classification of scar tissue in late gadolinium enhancement cardiac MRI for the assessment of left-atrial wall injury after radiofrequency ablation.

    PubMed

    Perry, Daniel; Morris, Alan; Burgon, Nathan; McGann, Christopher; Macleod, Robert; Cates, Joshua

    2012-02-23

    Radiofrequency ablation is a promising procedure for treating atrial fibrillation (AF) that relies on accurate lesion delivery in the left atrial (LA) wall for success. Late Gadolinium Enhancement MRI (LGE MRI) at three months post-ablation has proven effective for noninvasive assessment of the location and extent of scar formation, which are important factors for predicting patient outcome and planning of redo ablation procedures. We have developed an algorithm for automatic classification in LGE MRI of scar tissue in the LA wall and have evaluated accuracy and consistency compared to manual scar classifications by expert observers. Our approach clusters voxels based on normalized intensity and was chosen through a systematic comparison of the performance of multivariate clustering on many combinations of image texture. Algorithm performance was determined by overlap with ground truth, using multiple overlap measures, and the accuracy of the estimation of the total amount of scar in the LA. Ground truth was determined using the STAPLE algorithm, which produces a probabilistic estimate of the true scar classification from multiple expert manual segmentations. Evaluation of the ground truth data set was based on both inter- and intra-observer agreement, with variation among expert classifiers indicating the difficulty of scar classification for a given a dataset. Our proposed automatic scar classification algorithm performs well for both scar localization and estimation of scar volume: for ground truth datasets considered easy, variability from the ground truth was low; for those considered difficult, variability from ground truth was on par with the variability across experts.

  19. Post-Acceleration Chaotic Atrial Rhythm

    DTIC Science & Technology

    1982-04-01

    atrial flutter or two discrete P-wave morphologies with the rate less fibrillation. than 100 bpm). and sinus bradycardia. An occasional The time...mulhilocal paroxysmal atrial tach.- cardia with cclic Wcnckchach phenomenon under observation examinations. The chaotic atrial rhythm in this case ji r 13...CHAOTIC ATRIAL RHYTHM Final Report 1 July 81 - 30 July 81 6. PERFORMING OIG. REPORT NUMBER 7. AUTHOR(s) 8 CONTRACT OR GRANT NUMBERS) r James E

  20. Quantitative modeling of the accuracy in registering preoperative patient-specific anatomic models into left atrial cardiac ablation procedures

    SciTech Connect

    Rettmann, Maryam E. Holmes, David R.; Camp, Jon J.; Cameron, Bruce M.; Robb, Richard A.; Kwartowitz, David M.; Gunawan, Mia; Johnson, Susan B.; Packer, Douglas L.; Dalegrave, Charles; Kolasa, Mark W.

    2014-02-15

    Purpose: In cardiac ablation therapy, accurate anatomic guidance is necessary to create effective tissue lesions for elimination of left atrial fibrillation. While fluoroscopy, ultrasound, and electroanatomic maps are important guidance tools, they lack information regarding detailed patient anatomy which can be obtained from high resolution imaging techniques. For this reason, there has been significant effort in incorporating detailed, patient-specific models generated from preoperative imaging datasets into the procedure. Both clinical and animal studies have investigated registration and targeting accuracy when using preoperative models; however, the effect of various error sources on registration accuracy has not been quantitatively evaluated. Methods: Data from phantom, canine, and patient studies are used to model and evaluate registration accuracy. In the phantom studies, data are collected using a magnetically tracked catheter on a static phantom model. Monte Carlo simulation studies were run to evaluate both baseline errors as well as the effect of different sources of error that would be present in a dynamicin vivo setting. Error is simulated by varying the variance parameters on the landmark fiducial, physical target, and surface point locations in the phantom simulation studies. In vivo validation studies were undertaken in six canines in which metal clips were placed in the left atrium to serve as ground truth points. A small clinical evaluation was completed in three patients. Landmark-based and combined landmark and surface-based registration algorithms were evaluated in all studies. In the phantom and canine studies, both target registration error and point-to-surface error are used to assess accuracy. In the patient studies, no ground truth is available and registration accuracy is quantified using point-to-surface error only. Results: The phantom simulation studies demonstrated that combined landmark and surface-based registration improved

  1. Prediction of very late arrhythmia recurrence after radiofrequency catheter ablation of atrial fibrillation: The MB-LATER clinical score.

    PubMed

    Mujović, Nebojša; Marinković, Milan; Marković, Nebojša; Shantsila, Alena; Lip, Gregory Y H; Potpara, Tatjana S

    2017-01-20

    Reliable prediction of very late recurrence of atrial fibrillation (VLRAF) occuring >12 months after catheter ablation (CA) in apparently "cured" patients could optimize long-term follow-up and modify decision-making regarding the discontinuation of oral anticoagulant therapy. In a single-centre cohort of consecutive patients post radiofrequency AFCA, we retrospectively derived a novel score for VLRAF prediction. Of 133 consecutive post AFCA patients (mean age 56.9 ± 11.8 years, 63.9% male, 69.2% with paroxysmal AF) who were arrhythmia-free at 12 months (excluding 3-month "blanking period"), 20 patients expirienced a VLRAF during a 29.1 ± 10.1-month follow-up, with a 3-year cumulative VLRAF rate of 31.1%. The MB-LATER score (Male, Bundle brunch block, Left atrium ≥47 mm, Type of AF [paroxysmal, persistent or long-standing persistent], and ER-AF = early recurrent AF), had better predictive ability for VLRAF (AUC 0.782) than the APPLE, ALARMc, BASE-AF2, CHADS2, CHA2DS2VASc or HATCH score (AUC 0.716, 0.671, 0.648, 0.552, 0.519 and 0.583, respectively), resulted in an improved net reclassification index (NRI) of 48.6-95.1% and better identified patients with subsequent VLRAF using decision-curve analysis (DCA). The MB-LATER score provides a readily available VLRAF risk assessment, and performs better than other scores. Validation of the MB-LATER score in other cohorts is underway.

  2. Prediction of very late arrhythmia recurrence after radiofrequency catheter ablation of atrial fibrillation: The MB-LATER clinical score

    PubMed Central

    Mujović, Nebojša; Marinković, Milan; Marković, Nebojša; Shantsila, Alena; Lip, Gregory Y. H.; Potpara, Tatjana S.

    2017-01-01

    Reliable prediction of very late recurrence of atrial fibrillation (VLRAF) occuring >12 months after catheter ablation (CA) in apparently “cured” patients could optimize long-term follow-up and modify decision-making regarding the discontinuation of oral anticoagulant therapy. In a single-centre cohort of consecutive patients post radiofrequency AFCA, we retrospectively derived a novel score for VLRAF prediction. Of 133 consecutive post AFCA patients (mean age 56.9 ± 11.8 years, 63.9% male, 69.2% with paroxysmal AF) who were arrhythmia-free at 12 months (excluding 3-month “blanking period”), 20 patients expirienced a VLRAF during a 29.1 ± 10.1-month follow-up, with a 3-year cumulative VLRAF rate of 31.1%. The MB-LATER score (Male, Bundle brunch block, Left atrium ≥47 mm, Type of AF [paroxysmal, persistent or long-standing persistent], and ER-AF = early recurrent AF), had better predictive ability for VLRAF (AUC 0.782) than the APPLE, ALARMc, BASE-AF2, CHADS2, CHA2DS2VASc or HATCH score (AUC 0.716, 0.671, 0.648, 0.552, 0.519 and 0.583, respectively), resulted in an improved net reclassification index (NRI) of 48.6–95.1% and better identified patients with subsequent VLRAF using decision-curve analysis (DCA). The MB-LATER score provides a readily available VLRAF risk assessment, and performs better than other scores. Validation of the MB-LATER score in other cohorts is underway. PMID:28106147

  3. Comparing energy sources for surgical ablation of atrial fibrillation: a Bayesian network meta-analysis of randomized, controlled trials.

    PubMed

    Phan, Kevin; Xie, Ashleigh; Kumar, Narendra; Wong, Sophia; Medi, Caroline; La Meir, Mark; Yan, Tristan D

    2015-08-01

    Simplified maze procedures involving radiofrequency, cryoenergy and microwave energy sources have been increasingly utilized for surgical treatment of atrial fibrillation as an alternative to the traditional cut-and-sew approach. In the absence of direct comparisons, a Bayesian network meta-analysis is another alternative to assess the relative effect of different treatments, using indirect evidence. A Bayesian meta-analysis of indirect evidence was performed using 16 published randomized trials identified from 6 databases. Rank probability analysis was used to rank each intervention in terms of their probability of having the best outcome. Sinus rhythm prevalence beyond the 12-month follow-up was similar between the cut-and-sew, microwave and radiofrequency approaches, which were all ranked better than cryoablation (respectively, 39, 36, and 25 vs 1%). The cut-and-sew maze was ranked worst in terms of mortality outcomes compared with microwave, radiofrequency and cryoenergy (2 vs 19, 34, and 24%, respectively). The cut-and-sew maze procedure was associated with significantly lower stroke rates compared with microwave ablation [odds ratio <0.01; 95% confidence interval 0.00, 0.82], and ranked the best in terms of pacemaker requirements compared with microwave, radiofrequency and cryoenergy (81 vs 14, and 1, <0.01% respectively). Bayesian rank probability analysis shows that the cut-and-sew approach is associated with the best outcomes in terms of sinus rhythm prevalence and stroke outcomes, and remains the gold standard approach for AF treatment. Given the limitations of indirect comparison analysis, these results should be viewed with caution and not over-interpreted.

  4. Segmentation of left atrial intracardiac ultrasound images for image guided cardiac ablation therapy

    NASA Astrophysics Data System (ADS)

    Rettmann, M. E.; Stephens, T.; Holmes, D. R.; Linte, C.; Packer, D. L.; Robb, R. A.

    2013-03-01

    Intracardiac echocardiography (ICE), a technique in which structures of the heart are imaged using a catheter navigated inside the cardiac chambers, is an important imaging technique for guidance in cardiac ablation therapy. Automatic segmentation of these images is valuable for guidance and targeting of treatment sites. In this paper, we describe an approach to segment ICE images by generating an empirical model of blood pool and tissue intensities. Normal, Weibull, Gamma, and Generalized Extreme Value (GEV) distributions are fit to histograms of tissue and blood pool pixels from a series of ICE scans. A total of 40 images from 4 separate studies were evaluated. The model was trained and tested using two approaches. In the first approach, the model was trained on all images from 3 studies and subsequently tested on the 40 images from the 4th study. This procedure was repeated 4 times using a leave-one-out strategy. This is termed the between-subjects approach. In the second approach, the model was trained on 10 randomly selected images from a single study and tested on the remaining 30 images in that study. This is termed the within-subjects approach. For both approaches, the model was used to automatically segment ICE images into blood and tissue regions. Each pixel is classified using the Generalized Liklihood Ratio Test across neighborhood sizes ranging from 1 to 49. Automatic segmentation results were compared against manual segmentations for all images. In the between-subjects approach, the GEV distribution using a neighborhood size of 17 was found to be the most accurate with a misclassification rate of approximately 17%. In the within-subjects approach, the GEV distribution using a neighborhood size of 19 was found to be the most accurate with a misclassification rate of approximately 15%. As expected, the majority of misclassified pixels were located near the boundaries between tissue and blood pool regions for both methods.

  5. Aircraft Flutter Testing

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Wilmer Reed gained international recognition for his innovative research, contributions and patented ideas relating to flutter and aeroelasticity of aerospace vehicles at Langley Research Center. In the early 1980's, Reed retired from Langley and joined the engineering staff of Dynamic Engineering Inc. While at DEI, Reed conceived and patented the DEI Flutter Exciter, now used world-wide in flight flutter testing of new or modified aircraft designs. When activated, the DEI Flutter Exciter alternately deflects the airstream upward and downward in a rapid manner, creating a force similar to that produced by an oscillating trailing edge flap. The DEI Flutter Exciter is readily adaptable to a variety of aircraft.

  6. Improvement in Quality of Life After Catheter Ablation for Paroxysmal Versus Long‐standing Persistent Atrial Fibrillation: A Prospective Study With 3‐Year Follow‐up

    PubMed Central

    Bulková, Veronika; Fiala, Martin; Havránek, Štěpán; Šimek, Jan; Škňouřil, Libor; Januška, Jaroslav; Špinar, Jindřich; Wichterle, Dan

    2014-01-01

    Background Changes in quality of life (QoL) after catheter ablation for long‐standing persistent atrial fibrillation (LSPAF) are not well described. We sought to compare QoL improvement after catheter ablation of paroxysmal atrial fibrillation (PAF) versus that after LSPAF. Methods and Results A total of 261 PAF and 126 LSPAF ablation recipients were prospectively followed for arrhythmia recurrence, QoL, hospital stay, and sick leave. In PAF versus LSPAF groups, 1.3±0.6 versus 1.6±0.7 procedures were performed per patient (P<0.00001) during a 3‐year follow‐up. Good arrhythmia control was achieved in 86% versus 87% of patients (P=0.69) and in 69% versus 69% of patients not receiving antiarrhythmic drugs (P=0.99). The baseline QoL was better in the PAF than in the LSPAF group (European Quality of Life Group instrument self‐report questionnaire visual analog scale: 66.4±14.2 versus 61.0±14.2, P=0.0005; European Quality of Life Group 3‐level, 5‐dimensional descriptive system: 71.4±9.2 versus 67.7±13.8, P=0.002). Postablation 3‐year increase in QoL was significant in both groups (all P<0.00001) and significantly lower in PAF versus LSPAF patients (visual analog scale: +5.0±14.5 versus +10.2±12.8, P=0.001; descriptive system: +5.9±14.3 versus +9.3±13.9, P=0.03). In multivariate analysis, LSPAF, less advanced age, shorter history of AF and good arrhythmia control were consistently associated with postablation 3‐year improvement in QoL. Days of hospital stay for cardiovascular reasons and days on sick leave per patient/year were significantly reduced in both groups. Conclusions Patients with LSPAF had worse baseline QoL. The magnitude of QoL improvement after ablation of LSPAF was significantly greater compared with after ablation of PAF, particularly when good arrhythmia control was achieved without the use of antiarrhythmic drugs. PMID:25037195

  7. Use of statins and recurrence of atrial fibrillation after catheter ablation or electrical cardioversion. A systematic review and meta-analysis.

    PubMed

    Dentali, Francesco; Gianni, Monica; Squizzato, Alessandro; Ageno, Walter; Castiglioni, Luana; Maroni, Lorenzo; Hylek, Elaine M; Grandi, Anna Maria; Cazzani, Eugenio; Venco, Achille; Guasti, Luigina

    2011-08-01

    Statins have important pleiotropic effects and have been shown to reduce vascular inflammation. Some evidence suggests that statins may have a role in the primary prevention of atrial fibrillation (AF), whereas little is know on the role of statins in patients with existing AF. We performed a meta-analysis of the literature to assess the effect of statins on the recurrence of AF after electrical cardioversion or ablation. MEDLINE and EMBASE databases were searched up to January 2010. Relative risks (RR) and 95% confidence intervals (CIs) were then calculated and pooled using a random-effects model. Statistical heterogeneity was evaluated through the use of I² statistics. Sixteen studies were included in our systematic review. Statins did not reduce the risk of AF recurrence after ablation (four studies including 750 patients; RR, 1.04; 95% CI, 0.85-1.28, p=0.71; I² = 34%). Conversely, the use of statins was associated with a significantly reduced risk of AF recurrence after electrical cardioversion (12 studies including 1790 patients; RR, 0.78; 95% CI, 0.67-0.90, p=0.0003; I² = 34%). This reduction was not statistically significant when the analysis was restricted to randomised controlled trials (RCTs) only (five studies, 458 patients, RR, 0.76; 95% CI, 0.48-1.20). In conclusion, statins may lower the risk of AF recurrence after electrical cardioversion, but not ablation. However, this finding should be considered with caution, and larger RCTs are warranted to confirm our preliminary results.

  8. Effect of whiskey on atrial vulnerability and "holiday heart".

    PubMed

    Engel, T R; Luck, J C

    1983-03-01

    Vulnerability to atrial fibrillation and flutter was examined in 11 alcohol abusers who did not have cardiomyopathy or manifest heart failure. Atrial extrastimulation was done with rapid pacing (drive cycle length 500 ms) to facilitate induction of atrial vulnerability, seen in four alcohol abusers. The remaining seven were retested 30 minutes after drinking 60 to 120 ml of 86 proof whiskey (ethanol blood levels were 49 to 101 mg/100 ml but pulmonary capillary wedge pressure remained normal in all) and atrial fibrillation or flutter was induced in three of the drinkers. Three nondrinkers, symptomatic with sinus bradycardia but not in heart failure, were found not to be vulnerable to atrial fibrillation or flutter, but flutter was induced in two of the three after drinking whiskey. Whiskey did not alter atrial functional refractory periods (mean +/- standard error of the mean 297 +/- 14 to 290 +/- 12 ms) or widen the dispersion among three disparate right atrial sites (57 +/- 13 to 47 +/- 12 ms). Thus, whiskey enhanced vulnerability to atrial fibrillation and flutter in patients without heart failure or cardiomyopathy, substantiating the "holiday heart" syndrome.

  9. Radiofrequency catheter ablation of the atrioventricular junction from the left ventricle

    SciTech Connect

    Sousa, J.; el-Atassi, R.; Rosenheck, S.; Calkins, H.; Langberg, J.; Morady, F. )

    1991-08-01

    The purpose of this study was to describe a new technique for catheter ablation of the atrioventricular junction using radiofrequency energy delivered in the left ventricle. Catheter ablation of the atrioventricular (AV) junction using a catheter positioned across the tricuspid annulus was unsuccessful in eight patients with a mean {plus minus} SD age of 51 {plus minus} 19 years who had AV nodal reentry tachycardia (three patients), orthodromic tachycardia using a concealed midseptal accessory pathway, atrial tachycardia, atrial flutter (two patients), or atrial fibrillation. Before attempts at catheter ablation of the AV junction, each patient had been refractory to pharmacological therapy, and four had failed attempts at either catheter modification of the AV node using radiofrequency energy or surgical and catheter ablation of the accessory pathway. Conventional right-sided catheter ablation of the AV junction using radiofrequency energy in six patients and both radiofrequency energy and direct current shocks in two patients was ineffective. The mean amplitude of the His bundle potential recorded at the tricuspid annulus at the sites of unsuccessful AV junction ablation was 0.1 {plus minus} 0.08 mV, with a maximum His amplitude of 0.03-0.28 mV. A 7F deflectable-tip quadripolar electrode catheter with a 4-mm distal electrode was positioned against the upper left ventricular septum using a retrograde aortic approach from the femoral artery. Third-degree AV block was induced in each of the eight patients with 20-36 W applied for 15-30 seconds. The His bundle potential at the sites of successful AV junction ablation ranged from 0.06 to 0.99 mV, with a mean of 0.27 {plus minus} 0.32 mV. There was no rise in the creatine kinase-MB fraction and no complications occurred. An intrinsic escape rhythm of 30-60 beats/min was present in seven of the eight patients.

  10. Experience of robotic catheter ablation in humans using a novel remotely steerable catheter sheath

    PubMed Central

    Wallace, Daniel T.; Goldenberg, Alex S.; Peters, Nicholas S.; Davies, D. Wyn

    2008-01-01

    Background A novel remotely controlled steerable guide catheter has been developed to enable precise manipulation and stable positioning of any eight French (Fr) or smaller electrophysiological catheter within the heart for the purposes of mapping and ablation. Objective To report our initial experience using this system for remotely performing catheter ablation in humans. Methods Consecutive patients attending for routine ablation were recruited. Various conventional diagnostic catheters were inserted through the left femoral vein in preparation for treating an accessory pathway (n = 1), atrial flutter (n = 2) and atrial fibrillation (n = 7). The steerable guide catheter was inserted into the right femoral vein through which various irrigated and non-irrigated tip ablation catheters were used. Conventional endpoints of loss of pathway conduction, bidirectional cavotricuspid isthmus block and four pulmonary vein isolation were used to determine acute procedural success. Results Ten patients underwent remote catheter ablation using conventional and/or 3D non-fluoroscopic mapping technologies. All procedural endpoints were achieved using the robotic control system without manual manipulation of the ablation catheter. There was no major complication. A radiation dosimeter positioned next to the operator 2.7 m away from the X-ray source showed negligible exposure despite a mean cumulative dose area product of 7,281.4 cGycm2 for all ten ablation procedures. Conclusions Safe and clinically effective remote navigation of ablation catheters can be achieved using a novel remotely controlled steerable guide catheter in a variety of arrhythmias. The system is compatible with current mapping and ablation technologies Remote navigation substantially reduces radiation exposure to the operator. Electronic supplementary material The online version of this article (doi:10.1007/s10840-007-9184-z) contains supplementary material, which is available to authorized users

  11. The APPLE Score – A Novel Score for the Prediction of Rhythm Outcomes after Repeat Catheter Ablation of Atrial Fibrillation

    PubMed Central

    Kornej, Jelena; Hindricks, Gerhard; Arya, Arash; Sommer, Philipp; Husser, Daniela; Bollmann, Andreas

    2017-01-01

    Background Arrhythmia recurrences after catheter ablation occur in up to 50% within one year but their prediction remains challenging. Recently, we developed a novel score for the prediction of rhythm outcomes after single AF ablation demonstrating superiority to other scores. The current study was performed to 1) prove the predictive value of the APPLE score in patients undergoing repeat AF ablation and 2) compare it with the CHADS2 and CHA2DS2-VASc scores. Methods Rhythm outcome between 3–12 months after AF ablation were documented. The APPLE score (one point for Age >65 years, Persistent AF, imPaired eGFR (<60 ml/min/1.73m2), LA diameter ≥43 mm, EF <50%) was calculated in every patient before procedure. Results 379 consecutive patients from The Leipzig Heart Center AF Ablation Registry (60±10 years, 65% male, 70% paroxysmal AF) undergoing repeat AF catheter ablation were included. Arrhythmia recurrences were observed in 133 patients (35%). While the CHADS2 (AUC 0.577, p = 0.037) and CHA2DS2-VASc scores (AUC 0.590, p = 0.015) demonstrated low predictive value, the APPLE score showed better prediction of arrhythmia recurrences (AUC 0.617, p = 0.002) than other scores (both p<0.001). Compared to patients with an APPLE score of 0, the risk (OR) for arrhythmia recurrences was 2.9, 3.0 and 6.0 (all p<0.01) for APPLE scores 1, 2, or ≥3, respectively. Conclusions The novel APPLE score is superior to the CHADS2 and CHA2DS2-VASc scores for prediction of rhythm outcomes after repeat AF catheter ablation. It may be helpful to identify patients with low, intermediate or high risk for recurrences after repeat procedure. PMID:28085921

  12. Simulating pulmonary vein activity leading to atrial fibrillation using a rule-based approach on realistic anatomical data.

    PubMed

    Reumann, M; Bohnert, J; Doessel, O

    2006-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia leading to a high rate of stroke. The underlying mechanisms of initiation and maintenance of AF are not fully understood. Several findings suggest a multitude of factors to leave the atria vulnerable to AF. In this work, a rule-based approach is taken to simulate the initiation of AF in a computer model for the purpose of generating a model with which the influence of anatomical structures, electrophysiological properties of the atria and arrhythmogenic activity can be evaluated. Pulmonary vein firing has been simulated leading to AF in 65.7 % of all simulations. The excitation pattern generated resemble chaotic excitation behavior, which is characteristic for AF as well as stable reentrant circuits responsible for atrial flutter. The findings compare well with literature. In future, the presented computer model of AF can be used in therapy planning such as ablation therapy or overdrive pacing.

  13. [Pharmacological versus invasive treatment in patients with atrial fibrillation].

    PubMed

    Pytkowski, Marciusz; Jankowska, Agnieszka; Kraska, Alicja; Sterliński, Maciej; Kowalik, Ilona; Krzyzanowski, Wojciech; Szwed, Hanna

    2004-06-01

    Aim of this prospective study was to assess quality of life (QoL), left ventricular (LV) function and exercise performance in two groups of patients (pts) with atrial fibrillation (Af) treated with: radiofrequency catheter ablation (RFA) and antiarrhythmic drugs (AA). Between 1996 and 2000 - 74 patients, 28 women, with drug refractory Af were enrolled by clinical indications for two modes of therapy: RFA and AA. RFA group consisted of 38 pts, 63.7 +/- 11.5 years old: 28 pts with RF AV Node ablation and pacemaker implantation (PI) and 10 pts with AV Node modification or right atrial isthmus RF ablation due to Af conversion to atrial flutter (Aflu) during medical therapy. AA group consisted of 36 pts, aged 59.7 +/- 13.8 years. Patients from RFA group suffered significantly more serious diseases than pts from AA group. No significant (sign.) differences between two groups were found in age, gender, arrhythmia history and number of AA taken. Pts were analyzed before entry, after 3 and 12 months of follow-up (3 mo. FU, 12 mo. FU) with following indices: LV function (Echo: EF & FS), exercise performance (treadmill test), QoL questionnaires, number of hospital admissions connected to arrhythmia or procedures (RFA & PI), number of AA drugs taken in RFA group. RFA group: Two deaths occurred due to end stage respiratory insufficiency (COPD), one pt required reposition of pacemaker lead. AA group: 3 pts required RFA due to uncontrolled Af/Aflu (AV Node ablation with PI - 1 pt, right atrial isthmus ablation - 2 pts). Analysis of two patients groups: LV function: Sign. improvement (EF & FS) in both groups in 12 mo. FU; Exercise performance: no sign. changes in 3 and 12 mo. FU. QoL: Arrhythmia scale: 3 mo. FU sign. reduction in both groups; 12 mo. FU reduction in RFA group only; Anxiety scale: 3 and 12 mo. FU sign. reduction of anxiety level in RFA group; Exercise and activity scales: 3 and 12 mo. FU sign. improvement in RFA group. During 3 and 12 mo. FU sign. less pts from RFA

  14. Endometrial ablation

    MedlinePlus

    Hysteroscopy-endometrial ablation; Laser thermal ablation; Endometrial ablation-radiofrequency; Endometrial ablation-thermal balloon ablation; Rollerball ablation; Hydrothermal ablation; Novasure ablation

  15. Radiofrequency Catheter Ablation Improves the Quality of Life Measured with a Short Form-36 Questionnaire in Atrial Fibrillation Patients: A Systematic Review and Meta-Analysis

    PubMed Central

    Choi, Jong-Il; Kim, Young-Hoon

    2016-01-01

    Background The main purpose of performing radiofrequency catheter ablation (RFCA) in atrial fibrillation (AF) patients is to improve the quality of life (QoL) and alleviate AF-related symptoms. We aimed to determine the qualitative and quantitative effects of RFCA on the QoL in AF patients. Methods We performed a systemic review and meta-analysis using a random effects model. We searched for the studies that reported the physical component summary score (PCS) and mental component summary score (MCS) of the short form-36, a validated system to assess and quantify the QoL, before and after RFCA in AF patients. PCS and MCS are T-scores with a mean of 50 and standard deviation of 10. Results Of the 470 studies identified through systematic search, we included 13 studies for pre-RFCA vs. the post-RFCA analysis and 5 studies for treatment success vs. AF recurrence analyses. In the pre-RFCA vs. post-RFCA analysis, RFCA was associated with a significant increase in both the PCS (weighted mean difference [WMD] = 6.33 [4.81–7.84]; p < 0.001) and MCS (WMD = 7.80 [6.15–9.44]; p < 0.001). The ΔPCS (post-RFCA PCS–pre-RFCA PCS) and ΔMCS values were used for the treatment success vs. AF recurrence analysis. Patients with successful ablation had a higher ΔPCS (WMD = 7.46 [4.44–10.49]; p < 0.001) and ΔMCS (WMD = 7.59 [4.94–10.24]; p < 0.001). Conclusions RFCA is associated with a significant increase in the PCS and MCS in AF patients. Patients without AF recurrence after RFCA had a better improvement in the PCS and MCS than patients who had AF recurrence. PMID:27681507

  16. Flutter analysis using transversality theory

    NASA Technical Reports Server (NTRS)

    Afolabi, D.

    1993-01-01

    A new method of calculating flutter boundaries of undamped aeronautical structures is presented. The method is an application of the weak transversality theorem used in catastrophe theory. In the first instance, the flutter problem is cast in matrix form using a frequency domain method, leading to an eigenvalue matrix. The characteristic polynomial resulting from this matrix usually has a smooth dependence on the system's parameters. As these parameters change with operating conditions, certain critical values are reached at which flutter sets in. Our approach is to use the transversality theorem in locating such flutter boundaries using this criterion: at a flutter boundary, the characteristic polynomial does not intersect the axis of the abscissa transversally. Formulas for computing the flutter boundaries and flutter frequencies of structures with two degrees of freedom are presented, and extension to multi-degree of freedom systems is indicated. The formulas have obvious applications in, for instance, problems of panel flutter at supersonic Mach numbers.

  17. Flutter Research on Skin Panels

    NASA Technical Reports Server (NTRS)

    Kordes, Eldon E.; Tuovila, Weimer J.; Guy, Lawrence D.

    1960-01-01

    Representative experimental results are presented to show the current status of the panel flutter problem. Results are presented for unstiffened rectangular panels and for rectangular panels stiffened by corrugated backing. Flutter boundaries are established for all types of panels when considered on the basis of equivalent isotropic plates. The effects of Mach number, differential pressure, and aerodynamic heating on panel flutter are discussed. A flutter analysis of orthotropic panels is presented in the appendix.

  18. Estimating Effective Dose from Phantom Dose Measurements in Atrial Fibrillation Ablation Procedures and Comparison of MOSFET and TLD Detectors in a Small Animal Dosimetry Setting

    NASA Astrophysics Data System (ADS)

    Anderson-Evans, Colin David

    Two different studies will be presented in this work. The first involves the calculation of effective dose from a phantom study which simulates an atrial fibrillation (AF) ablation procedure. The second involves the validation of metal-oxide semiconducting field effect transistors (MOSFET) for small animal dosimetry applications as well as improved characterization of the animal irradiators on Duke University's campus. Atrial Fibrillation is an ever increasing health risk in the United States. The most common type of cardiac arrhythmia, AF is associated with increased mortality and ischemic cerebrovascular events. Managing AF can include, among other treatments, an interventional procedure called catheter ablation. The procedure involves the use of biplane fluoroscopy during which a patient can be exposed to radiation for as much as two hours or more. The deleterious effects of radiation become a concern when dealing with long fluoroscopy times, and because the AF ablation procedure is elective, it makes relating the risks of radiation ever more essential. This study hopes to quantify the risk through the derivation of dose conversion coefficients (DCCs) from the dose-area product (DAP) with the intent that DCCs can be used to provide estimates of effective dose (ED) for typical AF ablation procedures. A bi-plane fluoroscopic and angiographic system was used for the simulated AF ablation procedures. For acquisition of organ dose measurements, 20 diagnostic MOSFET detectors were placed at selected organs in a male anthropomorphic phantom, and these detectors were attached to 4 bias supplies to obtain organ dose readings. The DAP was recorded from the system console and independently validated with an ionization chamber and radiochromic film. Bi-plane fluoroscopy was performed on the phantom for 10 minutes to acquire the dose rate for each organ, and the average clinical procedure time was multiplied by each organ dose rate to obtain individual organ doses. The

  19. Atrial fibrillation in the elderly

    PubMed Central

    Franken, Roberto A.; Rosa, Ronaldo F.; Santos, Silvio CM

    2012-01-01

    This review discusses atrial fibrillation according to the guidelines of Brazilian Society of Cardiac Arrhythmias and the Brazilian Cardiogeriatrics Guidelines. We stress the thromboembolic burden of atrial fibrillation and discuss how to prevent it as well as the best way to conduct cases of atrial fibrillatios in the elderly, reverting the arrhythmia to sinus rhythm, or the option of heart rate control. The new methods to treat atrial fibrillation, such as radiofrequency ablation, new oral direct thrombin inhibitors and Xa factor inhibitors, as well as new antiarrhythmic drugs, are depicted. PMID:22916053

  20. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design.

    PubMed

    Calkins, Hugh; Kuck, Karl Heinz; Cappato, Riccardo; Brugada, Josep; Camm, A John; Chen, Shih-Ann; Crijns, Harry J G; Damiano, Ralph J; Davies, D Wyn; DiMarco, John; Edgerton, James; Ellenbogen, Kenneth; Ezekowitz, Michael D; Haines, David E; Haissaguerre, Michel; Hindricks, Gerhard; Iesaka, Yoshito; Jackman, Warren; Jalife, Jose; Jais, Pierre; Kalman, Jonathan; Keane, David; Kim, Young-Hoon; Kirchhof, Paulus; Klein, George; Kottkamp, Hans; Kumagai, Koichiro; Lindsay, Bruce D; Mansour, Moussa; Marchlinski, Francis E; McCarthy, Patrick M; Mont, J Lluis; Morady, Fred; Nademanee, Koonlawee; Nakagawa, Hiroshi; Natale, Andrea; Nattel, Stanley; Packer, Douglas L; Pappone, Carlo; Prystowsky, Eric; Raviele, Antonio; Reddy, Vivek; Ruskin, Jeremy N; Shemin, Richard J; Tsao, Hsuan-Ming; Wilber, David

    2012-03-01

    This is a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation, developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology and the European Cardiac Arrhythmia Society (ECAS), and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). This is endorsed by the governing bodies of the ACC Foundation, the AHA, the ECAS, the EHRA, the STS, the APHRS, and the HRS.

  1. Results of Cryoablation for Atrial Fibrillation Concomitant With Video-Assisted Minimally Invasive Mitral Valve Surgery.

    PubMed

    Marchetto, Giovanni; Anselmino, Matteo; Rovera, Chiara; Mancuso, Samuel; Ricci, Davide; Antolini, Marina; Morello, Mara; Gaita, Fiorenzo; Rinaldi, Mauro

    2016-01-01

    Interest in minimally invasive video-assisted mitral valve surgery (MIMVS) is rapidly growing. Data on concomitant atrial fibrillation (AF) ablation to MIMVS are still lacking. The present study investigates the long-term results of AF cryoablation concomitant to MIMVS. From October 2006-September 2014, 68 patients with mitral valve disease (age 65.9 ± 11.1 years, 34 men out of 68 patients, Euroscore log 5.4 ± 4.5) and drug-resistant AF underwent MIMVS via right minithoracotomy and concomitant left-sided AF endocardial cryoablation (Cryoflex Medtronic, Minneapolis, MN). Patients were independently followed up by cardiological outpatient visits and underwent electrophysiological study when indicated. In total, 44 out of 68 patients (64.7%) underwent mitral valve repair and 8 patients (11.8%) also received concomitant tricuspid valve surgery. One procedure was electively converted to full sternotomy (1.5%). Total clamp time was 97.6 ± 22.8 minutes. In March 2015, 60 patients were alive and completed the follow-up after a mean of 3.4 ± 2.0 years following the procedure. In all, 48 patients (80%) presented sinus rhythm throughout the whole follow-up. Freedom from AF was respectively 95%, 87%, and 72% at 1, 3, and 5 years, respectively. We recorded 2 pacemaker implants (3.3%). A total of 3 patients suffered symptomatic recurrences (2 atypical atrial flutter and 1 atrial fibrillation) and underwent transcatheter ablation-all the 3 patients remained in stable sinus rhythm for the remaining follow-up. In conclusions, given the favorable long-term sinus rhythm maintenance rates of concomitant cryoablation, MIMVS can also be offered to patients with symptomatic AF. AF transcatheter ablation may easily avoid further symptomatic recurrences.

  2. Atrial Fibrillation

    MedlinePlus

    ... from the NHLBI on Twitter. What Is Atrial Fibrillation? Atrial fibrillation (A-tre-al fi-bri-LA- ... Works article. Understanding the Electrical Problem in Atrial Fibrillation In AF, the heart's electrical signals don't ...

  3. Real-time flutter identification

    NASA Technical Reports Server (NTRS)

    Roy, R.; Walker, R.

    1985-01-01

    The techniques and a FORTRAN 77 MOdal Parameter IDentification (MOPID) computer program developed for identification of the frequencies and damping ratios of multiple flutter modes in real time are documented. Physically meaningful model parameterization was combined with state of the art recursive identification techniques and applied to the problem of real time flutter mode monitoring. The performance of the algorithm in terms of convergence speed and parameter estimation error is demonstrated for several simulated data cases, and the results of actual flight data analysis from two different vehicles are presented. It is indicated that the algorithm is capable of real time monitoring of aircraft flutter characteristics with a high degree of reliability.

  4. Flutter suppression via piezoelectric actuation

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer

    1991-01-01

    Experimental flutter results obtained from wind tunnel tests of a two degree of freedom wind tunnel model are presented for the open and closed loop systems. The wind tunnel model is a two degree of freedom system which is actuated by piezoelectric plates configured as bimorphs. The model design was based on finite element structural analyses and flutter analyses. A control law was designed based on a discrete system model; gain feedback of strain measurements was utilized in the control task. The results show a 21 pct. increase in the flutter speed.

  5. Surgery for Atrial Fibrillation

    PubMed Central

    Lawrance, Christopher P.; Henn, Matthew C.; Damiano, Ralph J.

    2015-01-01

    Synopsis Atrial fibrillation is the most common cardiac arrhythmia and its treatment options include drug therapy or, catheter-based or surgical interventions. The surgical treatment of atrial fibrillation has undergone multiple evolutions over the last several decades. The Cox-Maze procedure which was developed by James Cox in 1987 is a procedure where multiple surgical incisions are created along the atria to interrupt the electrical pathways thought to allow atrial fibrillation to persist. This procedure went on to become the gold standard for the surgical treatment of atrial fibrillation and is currently in its 4th iteration called the Cox-Maze IV. The Cox-Maze IV replaced the previous “cut-and-sew” method with a combination of cryoablation and bipolar RF ablation. The adaption of ablation technologies allowed the Cox-Maze IV procedure to be performed through a less invasive right minithoracotomy instead of a traditional sternotomy approach. The aim of this article is to review the indications and preoperative planning for performing a Cox-Maze IV procedure. A description of the operative techniques for both a sternotomy and right mini-thoracotomy approach will be discussed in addition to specific postoperative considerations. Finally, this article will review the literature describing the surgical results for both approaches including comparisons of the Cox-Maze IV to the previous “cut-and-sew” method. PMID:25443237

  6. Detection of atrial arrhythmia for cardiac rhythm management by implantable devices.

    PubMed

    Morris, M M; KenKnight, B H; Lang, D J

    2000-01-01

    Implantable atrial defibrillators (IAD) should provide pacing therapy whenever appropriate (ie, typical atrial flutter) to minimize shock-related patient discomfort. Additionally, IADs should provide diagnostics regarding atrial arrhythmia type and frequency of occurrence to enable improved physician management of atrial arrhythmia. To achieve this, IADs should accurately classify atrial arrhythmia such as atrial fibrillation (AF) and atrial flutter (AFL) This article evaluates the performance of an algorithm, atrial rhythm classification (ARC), designed to classify AF and AFL. The ARC algorithm uses maximum rate, standard deviation, and range of the 12 most recent atrial cycle lengths to plot a point in a three-dimensional space. A decision boundary divides the space into 2 regions--faster/unstable atrial cycle lengths (AF) or slower/stable cycle lengths (AFL). Classifications are made on a sliding window of 12 consecutive cycles until the end of the episode is reached. In this way, continuous episode feedback is provided that can be used to help guide device therapy, measure arrhythmia type and frequency of occurrence. Bipolar (1-cm) electrogram episodes of AF (n = 16) and AFL (n = 7) were acquired from 20 patients and retrospectively analyzed using the ARC algorithm. The sensitivity and specificity in this study was 0.993 and 0.982, respectively. The ARC algorithm would have appropriately guided atrial therapy and minimized discomfort associated with defibrillation shocks in this small patient data set warranting further studies. The ARC algorithm may also be beneficial as a diagnostic tool to assist physician management of atrial arrhythmia.

  7. Health-related quality of life in different clinical subgroups with typical AFL who have undergone cavo-tricuspid isthmus ablation

    PubMed Central

    2012-01-01

    Background To evaluate changes in health-related quality of life (HRQOL) in different sub-groups of a cohort of patients with typical atrial flutter (AFL) treated with cavotricuspid isthmus (CTI) radiofrequency catheter ablation. Methods 95 consecutive patients due to undergo CTI ablation were enrolled in a study involving their completion of two SF-36 HRQOL questionnaires, before ablation and at one-year follow-up. Results 88 of the initial 95 patients finished the study. Regardless of whether patients experienced atrial fibrillation (AF) during follow-up, a statistically significant improvement in HRQOL was observed, compared with pre-ablation scores and in all dimensions except Bodily Pain. However, patients without AF during follow-up had significantly higher absolute HRQOL scores in most dimensions. No differences were seen in most HRQOL dimensions, with respect to AFL type (paroxysmal, persistent) or duration, whether AFL was first-episode or recurrent, Class I-III drug dependent, sex, or presence of structural heart disease or tachycardiomyopathy. Patients with persistent AFL showed the greatest improvement in HRQOL when they also had a ventricular cycle length ≤500 ms. The combination of recurrent AFL, ventricular cycle length ≤500 ms and structural heart disease led to a significantly greater improvement in physical HRQOL dimensions than did first-episode AFL, no structural heart disease and ventricular cycle >500 ms. The only independent factor associated with a greater improvement was structural cardiopathy. Conclusions CTI-ablation treatment leads to a significant improvement in HRQOL in patients with typical AFL. Patients with AF during follow-up show a significantly lower HRQOL at one-year post-ablation. The only independent risk factor found to be associated with a greater improvement in the physical summary component was structural cardiopathy. PMID:22866671

  8. [Atrial fibrillation].

    PubMed

    Cárdenas, Manuel

    2007-01-01

    Atrial fibrillation is an arrhythmia characterized by no-coordinated atrial contraction that results in an inefficient atrial systole. The clinical classification of atrial fibrillation includes: ocassional, paroxysmal, persistent, and permanent. Multiple mechanisms have been described and accounts for a single ECG manifestation. Treatment should be individualized and has to considered several aspects including age, associated heart disease, and symptoms. Treatment strategies are: rhythm control, rate control, and thromboprophylaxis.

  9. 14 CFR 27.629 - Flutter.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.629 Flutter. Each aerodynamic surface of the rotorcraft must be free from flutter under each appropriate speed and power...

  10. Rhythm control in atrial fibrillation.

    PubMed

    Piccini, Jonathan P; Fauchier, Laurent

    2016-08-20

    Many patients with atrial fibrillation have substantial symptoms despite ventricular rate control and require restoration of sinus rhythm to improve their quality of life. Acute restoration (ie, cardioversion) and maintenance of sinus rhythm in patients with atrial fibrillation are referred to as rhythm control. The decision to pursue rhythm control is based on symptoms, the type of atrial fibrillation (paroxysmal, persistent, or long-standing persistent), patient comorbidities, general health status, and anticoagulation status. Many patients have recurrent atrial fibrillation and require further intervention to maintain long term sinus rhythm. Antiarrhythmic drug therapy is generally recommended as a first-line therapy and drug selection is on the basis of the presence or absence of structural heart disease or heart failure, electrocardiographical variables, renal function, and other comorbidities. In patients who continue to have recurrent atrial fibrillation despite medical therapy, catheter ablation has been shown to substantially reduce recurrent atrial fibrillation, decrease symptoms, and improve quality of life, although recurrence is common despite continued advancement in ablation techniques.

  11. State and development of flutter calculation

    NASA Technical Reports Server (NTRS)

    Teichmann, Alfred

    1951-01-01

    This report discusses the need for considering a wide variation in certain of the basic flutter parameters in conducting a flutter analysis. Conclusions are drawn stating that design charts or simple rules may be misleading. Due to inherent difficulties, dynamic model testing may also yield misleading results. The general flutter equations and various methods of solution are discussed. Of particular interest, curves are presented showing computational effort plotted against a number of degrees of freedom used in a flutter analysis.

  12. Fluttering in Stratified Flows

    NASA Astrophysics Data System (ADS)

    Lam, Try; Vincent, Lionel; Kanso, Eva

    2016-11-01

    The descent motion of heavy objects under the influence of gravitational and aerodynamic forces is relevant to many branches of engineering and science. Examples range from estimating the behavior of re-entry space vehicles to studying the settlement of marine larvae and its influence on underwater ecology. The behavior of regularly shaped objects freely falling in homogeneous fluids is relatively well understood. For example, the complex interaction of a rigid coin with the surrounding fluid will cause it to either fall steadily, flutter, tumble, or be chaotic. Less is known about the effect of density stratification on the descent behavior. Here, we experimentally investigate the descent of discs in both pure water and in a linearly salt-stratified fluids where the density is varied from 1.0 to 1.14 of that of water where the Brunt-Vaisala frequency is 1.7 rad/sec and the Froude number Fr < 1. We found that stratification enhances the radial dispersion of the disc at landing, and simultaneously, decrease the descent speed and the inclination (or nutation) angle while falling. We conclude by commenting on the relevance of these results to the use of unpowered vehicles and robots for space exploration and underwater missions.

  13. Flutter analysis of a sounding rocket fin

    NASA Astrophysics Data System (ADS)

    Natori, M.; Onoda, J.; Kitamura, T.

    The procedures used to characterize the flutter behavior of the fin of the ISAS M-3S II launch vehicle (capable of launching 750 kg to LEO) are described. Consideration is given to supersonic flutter computations, single-point-excitation and vibration testing, construction of flutter models, and transonic wind-tunnel tests. Tables, graphs, diagrams, and photographs are provided.

  14. Real-time flutter analysis

    NASA Technical Reports Server (NTRS)

    Walker, R.; Gupta, N.

    1984-01-01

    The important algorithm issues necessary to achieve a real time flutter monitoring system; namely, the guidelines for choosing appropriate model forms, reduction of the parameter convergence transient, handling multiple modes, the effect of over parameterization, and estimate accuracy predictions, both online and for experiment design are addressed. An approach for efficiently computing continuous-time flutter parameter Cramer-Rao estimate error bounds were developed. This enables a convincing comparison of theoretical and simulation results, as well as offline studies in preparation for a flight test. Theoretical predictions, simulation and flight test results from the NASA Drones for Aerodynamic and Structural Test (DAST) Program are compared.

  15. Optical Detection of Blade Flutter

    NASA Technical Reports Server (NTRS)

    Nieberding, W. C.; Pollack, J. L.

    1977-01-01

    Dynamic strain gages mounted on rotor blades are used as the primary instrumentation for detecting the onset of flutter and defining the vibratory mode and frequency. Optical devices are evaluated for performing the same measurements as well as providing supplementary information on the vibratory characteristics. Two separate methods are studied: stroboscopic imagery of the blade tip and photoelectric scanning of blade tip motion. Both methods give visual data in real time as well as video tape records. The optical systems are described, and representative results are presented. The potential of this instrumentation in flutter research is discussed.

  16. Douglas Experience in Flight Flutter Testing

    NASA Technical Reports Server (NTRS)

    Philbrick, J.

    1975-01-01

    Douglas Aircraft Company experience in flight flutter testing is reviewed briefly, with comments on state-of-the-art excitation and instrumentation techniques used up to the present time. The limitations of previous techniques are discussed with emphasis on the problem of: (1) establishing a flutter margin of safety for predicted marginal flutter modes; (2) resolving instances of flutter not predicted by theoretical calculations in advance; and (3) delaying the airplane demonstration by time consumed in acquisition and reduction of flutter data. Current Douglas philosophy in flight flutter testing is presented and a description given of steady-state vane excitation system development, automatic data handling system, and the potential application of automatic computing methods for increasing flutter data yield.

  17. Remote Magnetic versus Manual Navigation for Radiofrequency Ablation of Paroxysmal Atrial Fibrillation: Long-Term, Controlled Data in a Large Cohort

    PubMed Central

    Berte, Benjamin; Vandekerckhove, Yves; Tavernier, Rene

    2017-01-01

    Purpose. We aimed to study long-term outcome after pulmonary vein isolation (PVI) guided by remote magnetic navigation (RMN) and provided comparative data to outcome after manual navigation (MAN). Methods. Three hundred thirty-six patients with symptomatic paroxysmal AF underwent PVI by irrigated point-by-point radiofrequency (RF) ablation (RMN, n = 114 versus MAN, n = 222). Patients were followed up with symptom guided rhythm monitoring for a period up to 43 months. The end point of the study was freedom from repeat ablation after a single procedure and without antiarrhythmic drug treatment (ADT). Results. At the end of follow-up (median 26.3 months), freedom from repeat ablation was comparable between RMN and MAN (70.9% versus 69.5%, p = 0.61). At repeat, mean number of reconnected veins was 2.4 ± 1.2 in RMN versus 2.6 ± 1.0 in MAN (p = 0.08). The majority of repeat procedures occurred during the first year (82.1% in RMN versus 78.5% in MAN; p = 0.74). Conclusion. On the long term (up to 3 years) and in a large cohort of patients with paroxysmal AF, RMN-guided PVI is as effective as MAN guided PVI. In both strategies the majority of repeat procedures occurred during the first year after index procedure. PMID:28386560

  18. [Anticoagulation in atrial fibrillation - an update].

    PubMed

    Antz, Matthias; Hullmann, Bettina; Neufert, Christian; Vocke, Wolfgang

    2008-12-01

    The correct anticoagulation regimen for prevention of thromboembolic events is essential in patients with atrial fibrillation. However, only a minority of patients receives anticoagulation according to the guidelines. The current guidelines are intended to make the indication for anticoagulation more simple and are summarized in the present article. This includes recommendations for chronic anticoagulation, prevention of thromboembolic events after cardioversion and in ablation of atrial fibrillation.

  19. Optical measurement of unducted fan flutter

    NASA Technical Reports Server (NTRS)

    Kurkov, Anatole P.; Mehmed, Oral

    1990-01-01

    A nonintrusive optical method is described for flutter vibrations in unducted fan or propeller rotors and provides detailed spectral results for two flutter modes of a scaled unducted fan. The measurements were obtained in a high-speed wind tunnel. A single-rotor and a dual-rotor counterrotating configuration of the model were tested; however, only the forward rotor of the counterrotating configuration fluttered. Conventional strain gages were used to obtain flutter frequency; optical data provided complete phase results and an indication of the flutter mode shape through the ratio of the leading- to trailing-edge flutter amplitudes near the blade tip. In the transonic regime exhibited some features that are usually associated with nonlinear vibrations. Experimental mode shape and frequencies were compared with calculated values that included centrifugal effects.

  20. Applying non-linear dynamics to atrial appendage flow data to understand and characterize atrial arrhythmia

    SciTech Connect

    Chandra, S.; Grimm, R.A.; Katz, R.; Thomas, J.D.

    1996-06-01

    The aim of this study was to better understand and characterize left atrial appendage flow in atrial fibrillation. Atrial fibrillation and flutter are the most common cardiac arrhythmias affecting 15% of the older population. The pulsed Doppler velocity profile data was recorded from the left atrial appendage of patients using transesophageal echocardiography. The data was analyzed using Fourier analysis and nonlinear dynamical tools. Fourier analysis showed that appendage mechanical frequency ({ital f{sub f}}) for patients in sinus rhythm was always lower (around1 Hz) than that in atrial fibrillation (5-8 Hz). Among patients with atrial fibrillation spectral power below {ital f{sub f}} was significantly different suggesting variability within this group of patients. Results that suggested the presence of nonlinear dynamics were: a) the existence of two arbitrary peak frequencies {ital f{sub 1}, f{sub 2}}, and other peak frequencies as linear combinations thereof ({ital mf{sub 1}{+-}nf{sub 2}}), and b) the similarity between the spectrum of patient data and that obtained using the Lorenz equation. Nonlinear analysis tools, including Phase plots and differential radial plots, were also generated from the velocity data using a delay of 10. In the phase plots, some patients displayed a torus-like structure, while others had a more random-like pattern. In the differential radial plots, the first set of patients (with torus-like phase plots) showed fewer values crossing an arbitrary threshold of 10 than did the second set (8 vs. 27 in one typical example). The outcome of cardioversion was different for these two set of patients. Fourier analysis helped to: differentiate between sinus rhythm and atrial fibrillation, understand the characteristics of the wide range of atrial fibrillation patients, and provide hints that atrial fibrillation could be a nonlinear process. Nonlinear dynamical tools helped to further characterize and sub-classify atrial fibrillation.

  1. A root locus based flutter synthesis procedure

    NASA Technical Reports Server (NTRS)

    Hajela, P.

    1983-01-01

    An efficient generalized constraint is proposed in the context of a nonlinear mathematical programming approach for the minimum weight design of wing structures for flutter considerations. The approach is based on a root locus analysis procedure that is better suited for flutter redesign than the conventionally used V-g method. The proposed flutter constraint does not require an actual computation of the flutter speed, allows prescription of meaningful margins of safety in the optimized design and lends itself to elegant computation of sensitivity information. The approach is implemented and results presented for representative structural models.

  2. Atrial Fibrillation: Diagnosis

    MedlinePlus

    ... this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Diagnosis Past Issues / Winter 2015 Table of Contents ... your body's cells and organs. Read More "Atrial Fibrillation" Articles Atrial Fibrillation / Who Is at Risk for ...

  3. Efficacy of anticoagulation in resolving left atrial and left atrial appendage thrombi: A transesophageal echocardiographic study

    NASA Technical Reports Server (NTRS)

    Jaber, W. A.; Prior, D. L.; Thamilarasan, M.; Grimm, R. A.; Thomas, J. D.; Klein, A. L.; Asher, C. R.

    2000-01-01

    BACKGROUND: Transesophageal echocardiography (TEE) is the gold standard for evaluation of the left atrium and the left atrial appendage (LAA) for the presence of thrombi. Anticoagulation is conventionally used for patients with atrial fibrillation to prevent embolization of atrial thrombi. The mechanism of benefit and effectiveness of thrombi resolution with anticoagulation is not well defined. METHODS AND RESULTS: We used a TEE database of 9058 consecutive studies performed between January 1996 and November 1998 to identify all patients with thrombi reported in the left atrium and/or LAA. One hundred seventy-four patients with thrombi in the left atrial cavity (LAC) and LAA were identified (1.9% of transesophageal studies performed). The incidence of LAA thrombi was 6.6 times higher than LAC thrombi (151 vs 23, respectively). Almost all LAC thrombi were visualized on transthoracic echocardiography (90.5%). Mitral valve pathology was associated with LAC location of thrombi (P <.0001), whereas atrial fibrillation or flutter was present in most patients with LAA location of thrombi. Anticoagulation of 47 +/- 18 days was associated with thrombus resolution in 80.1% of the patients on follow-up TEE. Further anticoagulation resulted in limited additional benefit. CONCLUSIONS: LAC thrombi are rare and are usually associated with mitral valve pathology. Transthoracic echocardiography is effective in identifying these thrombi. LAA thrombi occur predominantly in patients with atrial fibrillation or flutter. Short-term anticoagulation achieves a high rate of resolution of LAA and LAC thrombi but does not obviate the need for follow-up TEE.

  4. LED's and the "Fluttering Heart" Phenomenon.

    ERIC Educational Resources Information Center

    Jewett, John W., Jr.

    1993-01-01

    Describes the nineteenth-century parlor trick entitled the Fluttering Heart phenomenon which uses a red heart on a bright blue background. Discusses theories concerning the apparent fluttering. Suggests doing the trick with a red light-emitting diode in a darkened room. (MVL)

  5. 14 CFR 23.629 - Flutter.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... surfaces. (e) For turbopropeller-powered airplanes, the dynamic evaluation must include— (1) Whirl mode... damping as VD is approached. (c) Any rational analysis used to predict freedom from flutter, control... must be shown by analysis to be free from flutter up to VD/MD after fatigue failure, or obvious...

  6. 14 CFR 23.629 - Flutter.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... surfaces. (e) For turbopropeller-powered airplanes, the dynamic evaluation must include— (1) Whirl mode... damping as VD is approached. (c) Any rational analysis used to predict freedom from flutter, control... must be shown by analysis to be free from flutter up to VD/MD after fatigue failure, or obvious...

  7. Effectiveness of Early Invasive Therapy for Atrial Tachycardia in Adult Atrial-Baffle Survivors

    PubMed Central

    Zaidi, Ali N.; Morrison, Justin; Daniels, Curt J.; Kalbfleisch, Steven; Kertesz, Naomi J.

    2017-01-01

    Adults who underwent complex atrial baffling as children via Mustard or Senning procedures are at heightened risk for atrial arrhythmias. Antiarrhythmic therapies are typically ineffective in this population. Accordingly, our team of pediatric and adult electrophysiologists investigated the effectiveness of early invasive transbaffle-access techniques to perform early radiofrequency ablation at the source of these clinically significant arrhythmias. For this retrospective study, we selected 11 adult survivors of atrial baffling (mean age, 34 ± 9 yr) who underwent clinically indicated electrophysiologic study after no more than one trial of antiarrhythmic therapy. Using transbaffle-access techniques and 3-dimensional mapping of the venous atria, we found 12 inducible arrhythmias in 10 patients: intra-atrial reentrant tachycardia (n=6), atrioventricular nodal reentrant tachycardia (n=3), focal atrial tachycardia (n=2), and repetitive double firing of the atrioventricular node (n=1). Defining success as short- and midterm freedom from arrhythmia, we analyzed outcomes of radiofrequency ablation at 1 and 6 months. At 1 month, ablation was 100% successful. At 6 months, after 11 ablations in 9 patients, 5 patients had no clinical recurrence, 2 had improved arrhythmia control from minimal medical therapy, and 2 were to undergo repeat study for recurrent tachycardia. In the recurrence-free patients, arrhythmias during electrophysiology study matched the types found clinically before the study. To our knowledge, this is the largest one-year cohort of adult survivors of atrial baffling to have undergone study by a combined pediatric–adult electrophysiology team. We conclude that early invasive transbaffle access for ablating diverse atrial tachyarrhythmias was effective in these patients. PMID:28265208

  8. Flutter Boundary Identification From Simulation Time Histories

    NASA Technical Reports Server (NTRS)

    Baker, Myles; Goggin, P. J.

    1997-01-01

    While there has been much recent progress in simulating nonlinear aeroelastic systems, and in predicting many of the aeroelastic phenomena of concern in transport aircraft design (i.e. transonic flutter buckets), the utility of a simulation in generating an understanding of the flutter behavior is limited. This is due in part to the high cost of generating these simulations; and the implied limitation on the number of conditions that can be analyzed, but there are also some difficulties introduced by the very nature of a simulation. Flutter engineers have traditionally worked in the frequency domain, and are accustomed to describing the flutter behavior of an airplane in terms of its V-G and V-F (or Q-G and Q-F) plots and flutter mode shapes. While the V-G and V-F plots give information about how the dynamic response of an airplane changes as the airspeed is increased, the simulation only gives information about one isolated condition (Mach, airspeed, altitude, etc.). Therefore, where a traditional flutter analysis can let the engineer determine an airspeed at which an airplane becomes unstable, while a simulation only serves as a binary check: either the airplane is fluttering at this condition, or it is not. In this document, a new technique is described in which system identification is used to easily extract modal frequencies and damping ratios from simulation time histories, and shows how the identified parameters can be used to determine the variation in frequency and dampin,o ratio as the airspeed is changed. This technique not only provides the flutter engineer with added insight into the aeroelastic behavior of the airplane, but it allows calculation of flutter mode shapes, and allows estimation of flutter boundaries while minimizing the number of simulations required.

  9. Recent topics on the surgical treatment for atrial fibrillation.

    PubMed

    Misaki, Takuro; Fukahara, Kazuaki

    2004-10-01

    After the introduction of endocardial radiofrequency catheter, only two arrhythmias, atrial fibrillation and ischemic ventricular tachycardia require surgical procedures. In this review, we describe recent advancements and problems of surgical treatment for atrial fibrillation. On the basis of multiple-circuit re-entry theory, Cox developed the maze operation with the aim of interrupting the re-entry circuit. Although this procedure has become the gold standard technique for the surgical treatment of atrial fibrillation with approximately 90% success rate, several modifications have been made over time. To obtain a more physiological atrial transport function, radial approach technique or bilateral appendage-preserved maze procedures were developed and to simplify surgical procedures, maze operation with cryo-ablation or radiofrequency-ablation were created. Other topics are concerned with surgical target or approach to atrial fibrillation. Ectopic focus theories from pulmonary veins have been widely recognized recently and the surgical isolation of pulmonary veins orifices is performed with various energy sources. In addition to standard cut-and-sew surgical technique, cryoablation, unipolar or bipolar radiofrequency ablation, or microwave ablation were induced with endocardial or epicardial approach for the achievement of less invasive cardiac surgery. As atrial fibrillation leads to frequent mortality, cardiac surgeons have to treat atrial fibrillation with other cardiac disease more frequently to obtain better quality of operative results.

  10. Airfoil flutter model suspension system

    NASA Technical Reports Server (NTRS)

    Reed, Wilmer H. (Inventor)

    1987-01-01

    A wind tunnel suspension system for testing flutter models under various loads and at various angles of attack is described. The invention comprises a mounting bracket assembly affixing the suspension system to the wind tunnel, a drag-link assembly and a compound spring arrangement comprises a plunge spring working in opposition to a compressive spring so as to provide a high stiffness to trim out steady state loads and simultaneously a low stiffness to dynamic loads. By this arrangement an airfoil may be tested for oscillatory response in both plunge and pitch modes while being held under high lifting loads in a wind tunnel.

  11. Sequential Hybrid Procedure for Persistent Atrial Fibrillation

    PubMed Central

    Bulava, Alan; Mokracek, Ales; Hanis, Jiri; Kurfirst, Vojtech; Eisenberger, Martin; Pesl, Ladislav

    2015-01-01

    Background Catheter ablation of persistent atrial fibrillation yields an unsatisfactorily high number of failures. The hybrid approach has recently emerged as a technique that overcomes the limitations of both surgical and catheter procedures alone. Methods and Results We investigated the sequential (staged) hybrid method, which consists of a surgical thoracoscopic radiofrequency ablation procedure followed by radiofrequency catheter ablation 6 to 8 weeks later using the CARTO 3 mapping system. Fifty consecutive patients (mean age 62±7 years, 32 males) with long‐standing persistent atrial fibrillation (41±34 months) and a dilated left atrium (>45 mm) were included and prospectively followed in an unblinded registry. During the electrophysiological part of the study, all 4 pulmonary veins were found to be isolated in 36 (72%) patients and a complete box‐lesion was confirmed in 14 (28%) patients. All gaps were successfully re‐ablated. Twelve months after the completed hybrid ablation, 47 patients (94%) were in normal sinus rhythm (4 patients with paroxysmal atrial fibrillation required propafenone and 1 patient underwent a redo catheter procedure). The majority of arrhythmias recurred during the first 3 months. Beyond 12 months, there were no arrhythmia recurrences detected. The surgical part of the procedure was complicated by 7 (13.7%) major complications, while no serious adverse events were recorded during the radiofrequency catheter part of the procedure. Conclusions The staged hybrid epicardial–endocardial treatment of long‐standing persistent atrial fibrillation seems to be extremely effective in maintenance of normal sinus rhythm compared to radiofrequency catheter or surgical ablation alone. Epicardial ablation alone cannot guarantee durable transmural lesions. Clinical Trial Registration URL: www.ablace.cz Unique identifier: cz‐060520121617 PMID:25809548

  12. Subsonic-transonic stall flutter study

    NASA Technical Reports Server (NTRS)

    Stardter, H.

    1979-01-01

    The objective of the Subsonic/Transonic Stall Flutter Program was to obtain detailed measurements of both the steady and unsteady flow field surrounding a rotor and the mechanical state of the rotor while it was operating in both steady and flutter modes to provide a basis for future analysis and for development of theories describing the flutter phenomenon. The program revealed that while all blades flutter at the same frequency, they do not flutter at the same amplitude, and their interblade phase angles are not equal. Such a pattern represents the superposition of a number of rotating nodal diameter patterns, each characterized by a different amplitude and different phase indexing, but each rotating at a speed that results in the same flutter frequency as seen in the rotor system. Review of the steady pressure contours indicated that flutter may alter the blade passage pressure distribution. The unsteady pressure amplitude contour maps reveal regions of high unsteady pressure amplitudes near the leading edge, lower amplitudes near the trailing.

  13. Supersonic flutter of composite sandwich panels

    NASA Astrophysics Data System (ADS)

    Shiau, Le-Chung

    1992-12-01

    A flutter-motion equation is presently derived for a 2D composite sandwich panel considering the total lateral displacement of the plate as the sum of the displacement due to bending of the plate, and that which is due to shear deformation at the core. The effects of core thickness and stacking sequence of the faces on the flutter boundary of the plate are discussed; it is shown that the sandwich panel greatly improves the flutter boundary over that of a composite laminate panel, provided it has sufficient core thickness.

  14. Effect of phenylephrine infusion on atrial electrophysiological properties.

    PubMed Central

    Leitch, J. W.; Basta, M.; Fletcher, P. J.

    1997-01-01

    OBJECTIVE: To determine the effect of changes in autonomic tone induced by phenylephrine infusion on atrial refractoriness and conduction. DESIGN: Left and right atrial electrophysiological properties were measured before and after a constant phenylephrine infusion designed to increase sinus cycle length by 25%. SUBJECTS: 20 patients, aged 53 (SD 6) years, undergoing electrophysiological study for investigation of idiopathic paroxysmal atrial fibrillation (seven patients) or for routine follow up after successful catheter ablation of supraventricular tachycardia (13 patients). MAIN OUTCOME MEASURES: Changes in left and right atrial effective refractory periods, atrial activation times, and frequency of induction of atrial fibrillation. RESULTS: Phenylephrine (mean dose 69 (SD 18) mg/min) increased mean blood pressure by 22 (12) mm Hg (range 7 to 44) and lengthened sinus cycle length by 223 (94) ms (20 to 430). Left atrial effective refractory period lengthened following phenylephrine infusion from 250 (25) to 264 (21) ms (P < 0.001) but there was no significant change in right atrial effective refractory period: 200 (20) v 206 (29), P = 0.11. There was a significant relation between the effect of phenylephrine on sinus cycle length and on right atrial refractoriness (r = 0.6, P = 0.005) with shortening of right atrial refractoriness in patients with the greatest prolongation in sinus cycle length. During phenylephrine infusion, the right atrial stimulus to left atrial activation time at the basic pacing cycle length of 600 ms was unchanged, at 130 (18) v 131 (17) ms, but activation delay with a premature extrastimulus increased: 212 (28) v 227 (38) ms, P = 0.002. Atrial fibrillation was induced by two of 58 refractory period measurements at baseline and by 12 of 61 measurements during phenylephrine infusion (P < 0.01). Phenylephrine increased the difference between left and right atrial refractory periods by 22.8 (19.4) ms in the five patients with induced atrial

  15. Idiopathic atrial fibrillation in a champion Standardbred racehorse.

    PubMed

    Stewart, G A; Fulton, L J; McKellar, C D

    1990-05-01

    Atrial fibrillation is described in a champion pacer which earlier had been named Australian Harness Horse of the Year as a 3-year-old in 1986-87. Prior to conversion atrial fibrillation had been present for at least 6 weeks, during which the horse had not raced. Successful treatment was achieved with two 10g doses of quinidine sulphate per oesophageal tube, after slow digitalisation with intravenous digoxin over 4d. Four hours after commencement of quinidine therapy the arrhythmia had regressed to atrial flutter and converted to sinus rhythm 10 min later. Considering his age, standard of racing and high reputation the horse's overall performance as a 5-year-old after conversion from atrial fibrillation appeared comparable to his previous performance as a 4-year-old before the disorder occurred. In one of the wins since his return to sinus rhythm, the horse recorded his fastest winning speed and created a new track record at the major Melbourne racetrack. The absence of abnormalities of atrial and atrio-ventricular conduction after the cessation of the arrhythmia, together with the horse's return to successful racing, indicate that this was case of atrial fibrillation occurring as a functional disorder without persistent atrial pathology.

  16. Active flutter suppression - Control system design and experimental validation

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.; Srinathkumar, S.

    1991-01-01

    The synthesis and experimental validation of an active flutter suppression controller for the Active Flexible Wing wind-tunnel model is presented. The design is accomplished with traditional root locus and Nyquist methods using interactive computer graphics tools and with extensive use of simulation-based analysis. The design approach uses a fundamental understanding of the flutter mechanism to formulate a simple controller structure to meet stringent design specifications. Experimentally, the flutter suppression controller succeeded in simultaneous suppression of two flutter modes, significantly increasing the flutter dynamic pressure despite errors in flutter dynamic pressure and flutter frequency in the mathematical model. The flutter suppression controller was also successfully operated in combination with a roll maneuver controller to perform flutter suppression during rapid rolling maneuvers.

  17. Active flutter suppression using dipole filters

    NASA Technical Reports Server (NTRS)

    Srinathkumar, S.; Waszak, Martin R.

    1992-01-01

    By using traditional control concepts of gain root locus, the active suppression of a flutter mode of a flexible wing is examined. It is shown that the attraction of the unstable mode towards a critical system zero determines the degree to which the flutter mode can be stabilized. For control situations where the critical zero is adversely placed in the complex plane, a novel compensation scheme called a 'Dipole' filter is proposed. This filter ensures that the flutter mode is stabilized with acceptable control energy. The control strategy is illustrated by designing flutter suppression laws for an active flexible wing (AFW) wind-tunnel model, where minimal control effort solutions are mandated by control rate saturation problems caused by wind-tunnel turbulence.

  18. Improved Flight Test Procedures for Flutter Clearance

    NASA Technical Reports Server (NTRS)

    Lind, Rick C.; Brenner, Martin J.; Freudinger, Lawrence C.

    1997-01-01

    Flight flutter testing is an integral part of flight envelope clearance. This paper discusses advancements in several areas that are being investigated to improve efficiency and safety of flight test programs. Results are presented from recent flight testing of the F/A-18 Systems Research Aircraft. A wingtip excitation system was used to generate aeroelastic response data. This system worked well for many flight conditions but still displayed some anomalies. Wavelet processing is used to analyze the flight data. Filtered transfer functions are generated that greatly improve system identification. A flutter margin is formulated that accounts for errors between a model and flight data. Worst-case flutter margins are computed to demonstrate the flutter boundary may lie closer to the flight envelope than previously estimated. This paper concludes with developments for a distributed flight analysis environment and on-line health monitoring.

  19. Aeroelastic flutter produces hummingbird feather songs.

    PubMed

    Clark, Christopher J; Elias, Damian O; Prum, Richard O

    2011-09-09

    During courtship flights, males of some hummingbird species produce diverse sounds with tail feathers of varying shapes. We show that these sounds are produced by air flowing past a feather, causing it to aeroelastically flutter and generate flutter-induced sound. Scanning laser doppler vibrometery and high-speed video of individual feathers of different sizes and shapes in a wind tunnel revealed multiple vibratory modes that produce a range of acoustic frequencies and harmonic structures. Neighboring feathers can be aerodynamically coupled and flutter either at the same frequency, resulting in sympathetic vibrations that increase loudness, or at different frequencies, resulting in audible interaction frequencies. Aeroelastic flutter is intrinsic to stiff airfoils such as feathers and thus explains tonal sounds that are common in bird flight.

  20. Atrial and ventricular tachyarrhythmias in military personnel.

    PubMed

    Posselt, Bonnie N; Cox, A T; D'Arcy, J; Rooms, M; Saba, M

    2015-09-01

    Although rare, sudden cardiac death does occur in British military personnel. In the majority of cases, the cause is considered to be a malignant ventricular tachyarrhythmia, which can be precipitated by a number of underlying pathologies. Conversely, a tachyarrhythmia may have a more benign and treatable cause, yet the initial clinical symptoms may be similar, making differentiation difficult. This is an overview of the mechanisms underlying the initiation and propagation of arrhythmias and the various pathological conditions that predispose to arrhythmia genesis, classified according to which parts of the heart are involved: atrial tachyarrhythmias, atrial and ventricular, as well as those affecting the ventricles alone. It encompasses atrial tachycardia, atrial flutter, supraventricular tachycardias and ventricular tachycardias, including the more commonly encountered inherited primary electrical diseases, also known as the channelopathies. The clinical features, investigation and management strategies are outlined. The occupational impact-in serving military personnel and potential recruits-is described, with explanations relating to the different conditions and their specific implication on continued military service.

  1. Stall flutter analysis of propfans

    NASA Technical Reports Server (NTRS)

    Reddy, T. S. R.

    1988-01-01

    Three semi-empirical aerodynamic stall models are compared with respect to their lift and moment hysteresis loop prediction, limit cycle behavior, easy implementation, and feasibility in developing the parameters required for stall flutter prediction of advanced turbines. For the comparison of aeroelastic response prediction including stall, a typical section model and a plate structural model are considered. The response analysis includes both plunging and pitching motions of the blades. In model A, a correction of the angle of attack is applied when the angle of attack exceeds the static stall angle. In model B, a synthesis procedure is used for angles of attack above static stall angles, and the time history effects are accounted for through the Wagner function.

  2. Flight flutter testing the B-58 airplane

    NASA Technical Reports Server (NTRS)

    Mahaffey, P. T.

    1975-01-01

    The flight flutter tests on the B-58 airplane are described, and the philosophy of flight flutter testing is discussed. The instrumentation used in the airplane and in the telemetering receiving station on the ground is described along with the methods used for exciting the airplane and the flight test procedure. Also described is the type of data obtained and its reduction. An evaluation of the procedure and instrumentation is given with a discussion of desirable improvements for future testing.

  3. Fan Stall Flutter Flow Mechanism Studied

    NASA Technical Reports Server (NTRS)

    Lepicovsky, Jan

    2002-01-01

    Modern turbofan engines employ a highly loaded fan stage with transonic or low-supersonic velocities in the blade-tip region. The fan blades are often prone to flutter at off-design conditions. Flutter is a highly undesirable and dangerous self-excited mode of blade oscillations that can result in high-cycle fatigue blade failure. The origins of blade flutter are not fully understood yet. Experimental data that can be used to clarify the origins of blade flutter in modern transonic fan designs are very limited. The Transonic Flutter Cascade Facility at the NASA Glenn Research Center was developed to experimentally study the details of flow mechanisms associated with fan flutter. The cascade airfoils are instrumented to measure high-frequency unsteady flow variations in addition to the steady flow data normally recorded in cascade tests. The test program measures the variation in surface pressure in response to the oscillation of one or more of the cascade airfoils. However, during the initial phases of the program when all airfoils were in fixed positions, conditions were found where significant time variations in the pressures near the airfoil leading edges could be observed.

  4. Method for experimental determination of flutter speed by parameter identification

    NASA Technical Reports Server (NTRS)

    Nissim, E.; Gilyard, Glenn B.

    1989-01-01

    A method for flight flutter testing is proposed which enables one to determine the flutter dynamic pressure from flights flown far below the flutter dynamic pressure. The method is based on the identification of the coefficients of the equations of motion at low dynamic pressures, followed by the solution of these equations to compute the flutter dynamic pressure. The initial results of simulated data reported in the present work indicate that the method can accurately predict the flutter dynamic pressure, as described. If no insurmountable difficulties arise in the implementation of this method, it may significantly improve the procedures for flight flutter testing.

  5. Atrial Fibrillation: Treatment

    MedlinePlus

    ... this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Treatment Past Issues / Winter 2015 Table of Contents Treatment for atrial fibrillation depends on how often you have symptoms, how ...

  6. Atrial Fibrillation: Complications

    MedlinePlus

    ... this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Complications Past Issues / Winter 2015 Table of Contents ... two major complications—stroke and heart failure. Atrial Fibrillation and Stroke Click to enlarge image This illustration ...

  7. Automatic Detection of Atrial Fibrillation for Mobile Devices

    NASA Astrophysics Data System (ADS)

    Kaiser, Stefanie; Kirst, Malte; Kunze, Christophe

    Two versions of a new detector for automatic real-time detection of atrial fibrillation in non-invasive ECG signals are introduced. The methods are based on beat to beat variability, tachogram analysis and simple signal filtering. The implementation on mobile devices is made possible due to the low demand on computing power of the employed analysis procedures. The proposed algorithms correctly identified 436 of 440 five minute episodes of atrial fibrillation or flutter and also correctly identified up to 302 of 342 episodes of no atrial fibrillation, including normal sinus rhythm as well as other cardiac arrhythmias. These numbers correspond to a sensitivity of 99.1 % and a specificity of 88.3%.

  8. Atrial Fibrillation.

    PubMed

    Zimetbaum, Peter

    2017-03-07

    This issue provides a clinical overview of atrial fibrillation, focusing on diagnosis, treatment, and practice improvement. The content of In the Clinic is drawn from the clinical information and education resources of the American College of Physicians (ACP), including MKSAP (Medical Knowledge and Self-Assessment Program). Annals of Internal Medicine editors develop In the Clinic in collaboration with the ACP's Medical Education and Publishing divisions and with the assistance of additional science writers and physician writers.

  9. 14 CFR 29.629 - Flutter and divergence.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.629 Flutter and divergence. Each aerodynamic surface of the rotorcraft must be free from flutter and divergence under...

  10. Investigating relationships between left atrial volume, symmetry, and sphericity

    NASA Astrophysics Data System (ADS)

    Menon, Prahlad G.; Nedios, Sotiris; Hindricks, Gerhard; Bollmann, Andreas

    2016-03-01

    Catheter ablation is a safe and effective therapy for drug-refractory patients symptomatic of atrial fibrillation (AF), with up to 80% of patients experiencing long-term arrhythmia-free survival. However, up to 20-40% of patients require more than one procedure in order to become arrhythmia-free. Therefore, appropriate patient selection is paramount to the effective implementation and long-term success of ablation therapy for patients with atrial fibrillation (AF). In this study, as a precursor to evaluating clinical significance of specific LA shape metrics as pre-procedural predictors of AF recurrence following ablative pulmonary vein isolation therapy, we report on a computational geometric analysis in a pilot cohort evaluating relationships between various patient-specific metrics of LA shape which might have such predictive value. This study specifically is focused on establishing the relationship between LA volume and sphericity, using a novel methodology for computing atrial sphericity based on regional shape.

  11. Flutter calculations in three degrees of freedom

    NASA Technical Reports Server (NTRS)

    Theodorsen, Theodore; Garrick, I E

    1942-01-01

    The present paper is a continuation of the general study of flutter published in NACA reports nos. 496 and 685. The paper is mainly devoted to flutter in three degrees of freedom (bending, torsion, and aileron) for which a number of selected cases have been calculated and presented in graphical form. The results are analyzed and discussed with regard to the effects of structural damping, of fractional-span ailerons, and of mass-balancing. The analysis shows that more emphasis should be put on the effect of structural damping and less on mass-balancing. The conclusion is drawn that a definite minimum amount of structural damping, which is usually found to be present, is essential in the calculations for an adequate description of the flutter case. Theoretical flutter predictions are thus brought into closer agreement with the facts of experience. A brief discussion is included of a particular biplane that had experienced flutter at about 200 miles per hour. Some simplifications have been achieved in the method of calculation. (author)

  12. Flutter of aircraft engine turbine blades

    NASA Astrophysics Data System (ADS)

    Panovsky, Josef, Jr.

    1997-11-01

    The goal of this research is to eliminate occurrences of flutter of low-pressure turbine blades in aircraft engines. Fundamental unsteady aerodynamic experiments in an annular cascade plus correlating analyses are conducted to improve the understanding of the flutter mechanism in these blades and to identify the key flutter parameters. The use of two- and three-dimensional linearized Euler methods for the calculation of the unsteady pressures due to the blade motion are validated through detailed comparison with the experimental data. Unexpected features of the steady and unsteady flows are also investigated using these computational tools. The validated computer codes are used to extend the range of the experimental data in a series of parametric studies, where the influence of mode shape, reduced frequency, and blade loading are investigated. Mode shape is identified as the most important contributor to determining the stability of a blade design. A new stability parameter is introduced to gain additional insight into the key contributors to flutter. This stability parameter is derived from the influence coefficient representation of the cascade, and includes only contributions from the reference blade and its immediate neighbors. This has the effect of retaining the most important contributions while filtering out terms of less significance. Design rules for the preliminary concept phase and procedures for the detailed analysis phase of the typical blade design process are defined. Utilization of these procedures will lead to blade designs which are free of flutter.

  13. Flutter of laminated plates in supersonic flow

    NASA Technical Reports Server (NTRS)

    Sawyer, J. W.

    1975-01-01

    A solution procedure was developed using linear small deflection theory for the flutter of simply supported laminated plates. For such plates, the bending and extensional governing equations are coupled and have cross-stiffness terms which do not appear in classical plate theory. An extended Galerkin method is used to obtain approximate solutions to the governing equations, and the aerodynamic pressure loading used in the analysis is that given by linear piston theory with flow at arbitrary cross-flow angle. A limited parametric study was conducted for typical laminated composite plates. The calculations show that both the bending-extensional coupling and the cross-stiffness terms have a large destabilizing effect on flutter. Since classical plate theory does not consider bending-extensional coupling and cross stiffness terms, it usually gives inaccurate and nonconservative flutter boundaries for laminated plates.

  14. Adaptive Modal Identification for Flutter Suppression Control

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.; Drew, Michael; Swei, Sean S.

    2016-01-01

    In this paper, we will develop an adaptive modal identification method for identifying the frequencies and damping of a flutter mode based on model-reference adaptive control (MRAC) and least-squares methods. The least-squares parameter estimation will achieve parameter convergence in the presence of persistent excitation whereas the MRAC parameter estimation does not guarantee parameter convergence. Two adaptive flutter suppression control approaches are developed: one based on MRAC and the other based on the least-squares method. The MRAC flutter suppression control is designed as an integral part of the parameter estimation where the feedback signal is used to estimate the modal information. On the other hand, the separation principle of control and estimation is applied to the least-squares method. The least-squares modal identification is used to perform parameter estimation.

  15. Atrial fibrillation

    PubMed Central

    Munger, Thomas M.; Wu, Li-Qun; Shen, Win K.

    2014-01-01

    Atrial fibrillation is the most common arrhythmia affecting patients today. Disease prevalence is increasing at an alarming rate worldwide, and is associated with often catastrophic and costly consequences, including heart failure, syncope, dementia, and stroke. Therapies including anticoagulants, anti-arrhythmic medications, devices, and non-pharmacologic procedures in the last 30 years have improved patients' functionality with the disease. Nonetheless, it remains imperative that further research into AF epidemiology, genetics, detection, and treatments continues to push forward rapidly as the worldwide population ages dramatically over the next 20 years. PMID:24474959

  16. Surgical Techniques Used for the Treatment of Atrial Fibrillation

    PubMed Central

    Robertson, Jason O.; Lawrance, Christopher P.; Maniar, Hersh S.; Damiano, Ralph J.

    2015-01-01

    The use of surgical lesion sets for the treatment of atrial fibrillation has been increasing, particularly in patients with complicated anatomical substrates and those undergoing concomitant surgery. Preferences in terms of lesion set, surgical approach and ablation technology vary by center. This review discusses both the surgical techniques and the outcomes for the most commonly performed procedures in the context of recent consensus guidelines. The Cox-Maze IV, pulmonary vein isolation, extended left atrial lesion sets, the hybrid approach and ganglionated plexus ablation are each reviewed in an attempt to provide insight into current clinical practice and patient selection PMID:23823731

  17. Decoupler pylon: wing/store flutter suppressor

    NASA Technical Reports Server (NTRS)

    Reed, W. H., III (Inventor)

    1982-01-01

    A device for suspending a store from a support such as an aircraft wing and more specifically for increasing the flutter speed of an aircraft flying with attached store and reducing the sensitivity of flutter to changes in the pitch inertia and center of gravity location of the store is described. It comprises softspring where the store pitch mode is decoupled from support modes and a low frequency active control mechanism which maintains store alignment. A pneumatic suspension system both isolates the store in pitch and, under conditions of changing mean load, aligns the store with the wing to which it is attached.

  18. Evaluation of Aeroservoelastic Effects on Flutter

    NASA Technical Reports Server (NTRS)

    Nagaraja, K. S.; Felt, Larry R.; Kraft, Raymond

    1998-01-01

    This report presents work performed by The Boeing Company to satisfy the deliverable "Evaluation of aeroservoelastic Effects on Symmetric Flutter" for Subtask 7 of Reference 1. The objective of this report is to incorporate the improved methods for studying the effects of a closed-loop control system on the aeroservoelastic behavior of the airplane planned under NASA HSR technical Integration Task 20 work. Also, a preliminary evaluation of the existing pitch control laws on symmetric flutter of the TCA configuration was addressed."The goal is to develop an improved modeling methodology and perform design studies that account for the aero-structures-systems interaction effects.

  19. Transonic flutter calculations using the Euler equations

    NASA Technical Reports Server (NTRS)

    Bendiksen, Oddvar O.; Kousen, Kenneth A.

    1989-01-01

    In transonic flutter problems where shock motion plays an important part, it is believed that accurate predictions of the flutter boundaries will require the use of codes based on the Euler equations. Only Euler codes can obtain the correct shock location and shock strength, and the crucially important shock excursion amplitude and phase lag. The present study is based on the finite volume scheme developed by Jameson and Venkatakrishnan for the 2-D unsteady Euler equations. The equations are solved in integral form on a moving grid. The variable are pressure, density, Cartesian velocity components, and total energy.

  20. Flight flutter testing using pulse techniques

    NASA Technical Reports Server (NTRS)

    Stringham, R. H., Jr.; Lenk, E. J.

    1975-01-01

    A case of flutter developed at a speed lower than had been flown previously. This incident precipitated the routine procedure of pulsing control surfaces as well as the firing of explosive charges during speed build-ups. In the interest of rapid evaluation of results, simple methods of data reduction were used. A case history is presented where in the pulse technique predicted flutter by extrapolating decay rates obtained at subcritical speeds; in addition, a case is presented where no valid extrapolation could be made.

  1. Flutter Analysis of the X-33

    NASA Technical Reports Server (NTRS)

    Fowler, Samuel B.

    2000-01-01

    Flutter analysis performed in support of the X33 Advanced Technology Demonstrator is described. Analysis was conducted over a range of flow regimes using several different analysis codes. The finite element and aerodynamic models used in the analysis have undergone several years of development and refinement resulting in a high degree of model detail. The flutter analysis focuses on the area of three critical points within the vehicle's design trajectory at which full sets of external loads have previously been developed. A comparison between several different aerodynamic models is also made for the selected trajectory points.

  2. Subsonic/transonic stall flutter investigation of a rotating rig

    NASA Technical Reports Server (NTRS)

    Jutras, R. R.; Fost, R. B.; Chi, R. M.; Beacher, B. F.

    1981-01-01

    Stall flutter is investigated by obtaining detailed quantitative steady and aerodynamic and aeromechanical measurements in a typical fan rotor. The experimental investigation is made with a 31.3 percent scale model of the Quiet Engine Program Fan C rotor system. Both subsonic/transonic (torsional mode) flutter and supersonic (flexural) flutter are investigated. Extensive steady and unsteady data on the blade deformations and aerodynamic properties surrounding the rotor are acquired while operating in both the steady and flutter modes. Analysis of this data shows that while there may be more than one traveling wave present during flutter, they are all forward traveling waves.

  3. [Non-pharmacologic treatment of atrial fibrillation].

    PubMed

    Csanádi, Zoltán; Fazekas, Tamás; Varró, András

    2003-06-29

    The authors provide an update on non-pharmacological treatment of atrial fibrillation (AF). They emphasize that although antiarrhythmic drugs continue to be first-line therapy for the arrhythmia considered to be a cardiovascular epidemic, clinical research to develop non-pharmacological means of treatment has been unprecedentally intensified during the last decade. Electrical cardioversion is the most successful non-pharmacological method to restore sinus rhythm, also the efficacy and safety of AV node ablation for palliative ventricular rate-controll is established. "Hybrid" therapeutic procedures, involving combinations of pharmacological and non-pharmacological interventions have gained widespread use. Curative transcatheter ablation for arrhythmia prevention is to be considered in case of clinical suggestions that AF is initiated by a primary regular arrhythmia that is amenable to routine catheter ablation (secondary AF). Despite encouraging results, at this point in time, curative catheter ablation for primary AF may offer significant improvement or even cure only for a small subset of patients, mostly young individuals with normal heart, and paroxysmal AF with frequent, symptomatic episodes refractory to multiple antiarrhythmic drugs. These interventions are to be performed in the settings of a clinical research project in some institutions. Regarding pacemaker therapy in case of bradycardia indication, physiologic pacing (AAI or DDD) is associated with significantly lower incidence of atrial fibrillation than ventricular pacing. Large-scale randomized controlled trials are needed to assess the clinical value of specially designed implantable devices to prevent atrial fibrillation in patients with no conventional bradycardia indication. Also, technical optimization and proper clinical evaluation is needed for implantable atrioverters and implantable cardioverter defibrillators capable of atrial cardioversion therapy.

  4. 14 CFR 23.629 - Flutter.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... analysis used to predict freedom from flutter, control reversal and divergence must cover all speeds up to... criteria, and (iii) Has fixed-fin and fixed-stabilizer surfaces. (e) For turbopropeller-powered airplanes, the dynamic evaluation must include— (1) Whirl mode degree of freedom which takes into account...

  5. 14 CFR 23.629 - Flutter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) Any rational analysis used to predict freedom from flutter, control reversal and divergence must cover...-stabilizer surfaces. (e) For turbopropeller-powered airplanes, the dynamic evaluation must include— (1) Whirl mode degree of freedom which takes into account the stability of the plane of rotation of the...

  6. 14 CFR 23.629 - Flutter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...) Any rational analysis used to predict freedom from flutter, control reversal and divergence must cover...-stabilizer surfaces. (e) For turbopropeller-powered airplanes, the dynamic evaluation must include— (1) Whirl mode degree of freedom which takes into account the stability of the plane of rotation of the...

  7. Minimally invasive surgery for atrial fibrillation

    PubMed Central

    Suwalski, Piotr

    2013-01-01

    Atrial fibrillation (AF) remains the most common cardiac arrhythmia, affecting nearly 2% of the general population worldwide. Minimally invasive surgical ablation remains one of the most dynamically evolving fields of modern cardiac surgery. While there are more than a dozen issues driving this development, two seem to play the most important role: first, there is lack of evidence supporting percutaneous catheter based approach to treat patients with persistent and long-standing persistent AF. Paucity of this data offers surgical community unparalleled opportunity to challenge guidelines and change indications for surgical intervention. Large, multicenter prospective clinical studies are therefore of utmost importance, as well as honest, clear data reporting. Second, a collaborative methodology started a long-awaited debate on a Heart Team approach to AF, similar to the debate on coronary artery disease and transcatheter valves. Appropriate patient selection and tailored treatment options will most certainly result in better outcomes and patient satisfaction, coupled with appropriate use of always-limited institutional resources. The aim of this review, unlike other reviews of minimally invasive surgical ablation, is to present medical professionals with two distinctly different, approaches. The first one is purely surgical, Standalone surgical isolation of the pulmonary veins using bipolar energy source with concomitant amputation of the left atrial appendage—a method of choice in one of the most important clinical trials on AF—The Atrial Fibrillation Catheter Ablation Versus Surgical Ablation Treatment (FAST) Trial. The second one represents the most complex approach to this problem: a multidisciplinary, combined effort of a cardiac surgeon and electrophysiologist. The Convergent Procedure, which includes both endocardial and epicardial unipolar ablation bonds together minimally invasive endoscopic surgery with electroanatomical mapping, to deliver best of

  8. Evaluation of Aeroservoelastic Effects on Flutter

    NASA Technical Reports Server (NTRS)

    Nagaraja, K. S.; Kraft, raymond; Felt, Larry

    1998-01-01

    The HSCT Flight Controls Group is developing a longitudinal control law, known as Gamma-dot / V, for the NASA HSR program. Currently, this control law is based on a quasi-steady aeroelastic (QSAE) model of the vehicle. This control law was implemented into the p-k flutter analysis process for closed loop aeroservoelastic analysis. The available flexible models, developed for the TCA aeroelastic analysis, were used to assess the effect of control laws on flutter at several different Mach numbers and mass conditions. Significant structures and flight control system interaction was observed during the initial assessment. Figures 1 and 2 present a summary of the effect of total closed loop gain and phase on flutter mechanisms, based on ideal sensors and real sensors, for Mach 0.95 and mass M02 condition. Control laws based on ideal sensors gave rise to increased coupling between the rigid body short period mode and the first symmetric elastic mode. This reduced the stability margins for the first elastic mode and does not meet the required 6 dB gain margin requirement. The effect of "real" sensors significantly increased the structures and control system interactions. This caused the elastic,modes to be highly unstable throughout most of the flight envelope. State-space models were developed for several conditions and then MATLAB program was used for the aeroservoelastic stability analysis. These results provided an independent verification of the p-k flutter analysis findings. Good overall agreement was observed between the p-k flutter analysis and state-space model results for both damping and frequency comparisons. These results are also included in this document.

  9. [Significance of tachycardia induced by atrial stimulation in Wolff-Parkinson-White syndrome].

    PubMed

    Brembilla-Perrot, B

    1992-04-01

    Increased atrial vulnerability is one of the criteria of malignant Wolff-Parkinson-White syndrome. The aim of this study was to try to define the methods of induction of atrial tachycardias (tachycardia, flutter, fibrillation) by endocavitary and oesophageal stimulation characterising an increased vulnerability. The incidence of induced sustained tachycardia by fixed atrial stimulation at incremental rates until the Wenckebach point is attained and programmed atrial stimulation using 1 and 2 extrastimuli under basal conditions and then with isoproterenol was compared in subjects without cardiac disease, Wolff-Parkinson-White or spontaneous tachycardia (Group I) and patients with Wolff-Parkinson-White and spontaneous tachycardias (Group II). Atrial stimulation only induced tachycardia in 2.5% of normal subjects under basal conditions or with isoproterenol, by the endocavitary or oesophageal approaches. Programmed stimulation induced tachycardia in 15% of normal subjects under basal conditions or with isoproterenol by the endocavitary approach alone. In Group II, tachycardia was reproduced under basal conditions or with isoproterenol by atrial stimulation or programmed stimulation in all patients. In conclusion, the induction of a tachyarrhythmia by incremental atrial stimulation up to the Wenckebach point is always pathological even with isoproterenol. Programmed atrial stimulation is less specific except by the oesophageal approach. The use of bursts of very rapid stimuli in the Wolff-Parkinson-White syndrome is of no value as tachycardia can be induced by classical methods in all subjects at risk.

  10. What Is Atrial Fibrillation?

    MedlinePlus

    ANSWERS by heart Cardiovascular Conditions What Is Atrial Fibrillation? Your heart has a natural pacemaker, called the “ ... if the electric signals are normal. In atrial fibrillation (AFib), the heart’s two small upper chambers (atria) ...

  11. Multifunction tests of a frequency domain based flutter suppression system

    NASA Technical Reports Server (NTRS)

    Christhilf, David M.; Adams, William M., Jr.

    1992-01-01

    The process is described of analysis, design, digital implementation, and subsonic testing of an active control flutter suppression system for a full span, free-to-roll wind tunnel model of an advanced fighter concept. The design technique uses a frequency domain representation of the plant and used optimization techniques to generate a robust multi input/multi output controller. During testing in a fixed-in-roll configuration, simultaneous suppression of both symmetric and antisymmetric flutter was successfully shown. For a free-to-roll configuration, symmetric flutter was suppressed to the limit of the tunnel test envelope. During aggressive rolling maneuvers above the open-loop flutter boundary, simultaneous flutter suppression and maneuver load control were demonstrated. Finally, the flutter damping controller was reoptimized overnight during the test using combined experimental and analytical frequency domain data, resulting in improved stability robustness.

  12. Catheter ablation.

    PubMed

    Fromer, M; Shenasa, M

    1991-02-01

    Catheter ablation is gaining increasing interest for the therapy of symptomatic, sustained arrhythmias of various origins. The scope of this review is to give an overview of the biophysical aspects and major characteristics of some of the most widely used energy sources in catheter ablation, e.g., the discharge of conventional defibrillators, modified defibrillators, laser light, and radiofrequency current application. Results from animal studies are considered to explain the basic mechanisms of catheter ablation. The recent achievements with the use of radiofrequency current to modify or ablate cardiac conduction properties are outlined in more detail.

  13. Design procedures for flutter-free surface panels

    NASA Technical Reports Server (NTRS)

    Laurenson, R. M.; Mcpherson, J. I.

    1977-01-01

    An approach for the design of lightweight external surface panel configurations to preclude panel flutter was developed. Design procedures were developed for flat orthotropic panels under the interacting influence of parameters such as support flexibility, inplane loads, pressure differential, and flow angularity. The basic relationships required to define these design procedures were based on theoretical panel flutter analyses. Where possible, the design procedures were verified through comparison with available experimental panel flutter data.

  14. Atrial fibrillation: review of current treatment strategies.

    PubMed

    Xu, Joshua; Luc, Jessica G Y; Phan, Kevin

    2016-09-01

    Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in modern clinical practice, with an estimated prevalence of 1.5-2%. The prevalence of AF is expected to double in the next decades, progressing with age and increasingly becoming a global medical challenge. The first-line treatment for AF is often medical treatment with either rate control or anti-arrhythmic agents for rhythm control, in addition to anti-coagulants such as warfarin for stroke prevention in patient at risk. Catheter ablation has emerged as an alternative for AF treatment, which involves myocardial tissue lesions to disrupt the underlying triggers and substrates for AF. Surgical approaches have also been developed for treatment of AF, particularly for patients requiring concomitant cardiac surgery or those refractory to medical and catheter ablation treatments. Since the introduction of the Cox-Maze III, this procedure has evolved into several modern variations, including the use of alternative energy sources (Cox-Maze IV) such as radiofrequency, cryo-energy and microwave, as well as minimally invasive thoracoscopic epicardial approaches. Another recently introduced technique is the hybrid ablation approach, where in a single setting both epicardial thoracoscopic ablation lesions and endocardial catheter ablation lesions are performed by the cardiothoracic surgeon and cardiologist. There remains controversy surrounding the optimal approach for AF ablation, energy sources, and lesion sets employed. The goal of this article is review the history, classifications, pathophysiology and current treatment options for AF.

  15. Atrial fibrillation: review of current treatment strategies

    PubMed Central

    Xu, Joshua; Luc, Jessica G. Y.

    2016-01-01

    Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in modern clinical practice, with an estimated prevalence of 1.5–2%. The prevalence of AF is expected to double in the next decades, progressing with age and increasingly becoming a global medical challenge. The first-line treatment for AF is often medical treatment with either rate control or anti-arrhythmic agents for rhythm control, in addition to anti-coagulants such as warfarin for stroke prevention in patient at risk. Catheter ablation has emerged as an alternative for AF treatment, which involves myocardial tissue lesions to disrupt the underlying triggers and substrates for AF. Surgical approaches have also been developed for treatment of AF, particularly for patients requiring concomitant cardiac surgery or those refractory to medical and catheter ablation treatments. Since the introduction of the Cox-Maze III, this procedure has evolved into several modern variations, including the use of alternative energy sources (Cox-Maze IV) such as radiofrequency, cryo-energy and microwave, as well as minimally invasive thoracoscopic epicardial approaches. Another recently introduced technique is the hybrid ablation approach, where in a single setting both epicardial thoracoscopic ablation lesions and endocardial catheter ablation lesions are performed by the cardiothoracic surgeon and cardiologist. There remains controversy surrounding the optimal approach for AF ablation, energy sources, and lesion sets employed. The goal of this article is review the history, classifications, pathophysiology and current treatment options for AF. PMID:27747025

  16. Flutter Analysis of a Transonic Fan

    NASA Technical Reports Server (NTRS)

    Srivastava, R.; Bakhle, M. A.; Keith, T. G., Jr.; Stefko, G. L.

    2002-01-01

    This paper describes the calculation of flutter stability characteristics for a transonic forward swept fan configuration using a viscous aeroelastic analysis program. Unsteady Navier-Stokes equations are solved on a dynamically deforming, body fitted, grid to obtain the aeroelastic characteristics using the energy exchange method. The non-zero inter-blade phase angle is modeled using phase-lagged boundary conditions. Results obtained show good correlation with measurements. It is found that the location of shock and variation of shock strength strongly influenced stability. Also, outboard stations primarily contributed to stability characteristics. Results demonstrate that changes in blade shape impact the calculated aerodynamic damping, indicating importance of using accurate blade operating shape under centrifugal and steady aerodynamic loading for flutter prediction. It was found that the calculated aerodynamic damping was relatively insensitive to variation in natural frequency.

  17. Eigenspace techniques for active flutter suppression

    NASA Technical Reports Server (NTRS)

    Garrard, William L.; Liebst, Bradley S.; Farm, Jerome A.

    1987-01-01

    The use of eigenspace techniques for the design of an active flutter suppression system for a hypothetical research drone is discussed. One leading edge and two trailing edge aerodynamic control surfaces and four sensors (accelerometers) are available for each wing. Full state control laws are designed by selecting feedback gains which place closed loop eigenvalues and shape closed loop eigenvectors so as to stabilize wing flutter and reduce gust loads at the wing root while yielding accepatable robustness and satisfying constrains on rms control surface activity. These controllers are realized by state estimators designed using an eigenvalue placement/eigenvector shaping technique which results in recovery of the full state loop transfer characteristics. The resulting feedback compensators are shown to perform almost as well as the full state designs. They also exhibit acceptable performance in situations in which the failure of an actuator is simulated.

  18. A Presentation on Robust Flutter Margin Analysis and a Flutterometer

    NASA Technical Reports Server (NTRS)

    Lind, Rick C.

    1997-01-01

    This paper documents an invited presentation given to The Boeing Company, Seattle, Washington, on September 9, 1997. The audience consisted of structural dynamic and flight test engineers from the Boeing Commercial Airplane Group who were interested in discussing research which may be applied to future flight flutter test programs. A method to compute robust flutter margins is described which is a significant departure from traditional methods. This method uses the structured singular value, mu, to compute a flutter margin which directly accounts for modeling errors such that a worst-case flutter margin is computed with respect to those errors. This method may be applied in several ways. A post-flight application uses data sets from multiple test points to compute worst-case flutter margins and a worst-case flight envelope. An on-line implementation computes flutter margins at each test point to track the flutter margins during a flight test. This on-line implementation is the basis for a flutterometer flight test tool that displays the distance to flutter at a given test point. Such a tool was not previously possible using traditional flutter flight test analysis methods. The F/A-18 System Research Aircraft was used to demonstrate these applications using flight data recorded from test points throughout the flight envelope.

  19. SCAR arrow-wing active flutter suppression system

    NASA Technical Reports Server (NTRS)

    Gordon, C. K.; Visor, O. E.

    1977-01-01

    The potential performance and direct operating cost benefits of an active flutter suppression system (FSS) for the NASA arrow-wing supersonic cruise configuration were determined. A FSS designed to increase the flutter speed of the baseline airplane 20 percent. A comparison was made of the performance and direct operating cost between the FSS equipped aircraft and a previously defined configuration with structural modifications to provide the same flutter speed. Control system synthesis and evaluation indicated that a FSS could provide the increase in flutter speed without degrading airplane reliability, safety, handling qualities, or ride quality, and without increasing repeated loads or hydraulic and electrical power capacity requirements.

  20. Flutter Analysis of Annular Cascades in Counter Rotation

    NASA Astrophysics Data System (ADS)

    Nishino, Ryohei; Namba, Masanobu

    The paper studies the effect of neighboring blade rows on flutter characteristics of cascading blades. For this purpose the computation program to calculate the unsteady blade loading based on the unsteady lifting surface theory for contra-rotating annular cascades was formulated and coded. Then a computation program to solve the coupled bending-torsion flutter equation for the contra-rotating annular cascades was also developed. Some results of the flutter analysis are presented. The presence of the neighboring blade row gives rise to significant change in the critical flutter condition when the main acoustic duct mode is of cut-on state.

  1. Structural resonance and mode of flutter of hummingbird tail feathers.

    PubMed

    Clark, Christopher J; Elias, Damian O; Girard, Madeline B; Prum, Richard O

    2013-09-15

    Feathers can produce sound by fluttering in airflow. This flutter is hypothesized to be aeroelastic, arising from the coupling of aerodynamic forces to one or more of the feather's intrinsic structural resonance frequencies. We investigated how mode of flutter varied among a sample of hummingbird tail feathers tested in a wind tunnel. Feather vibration was measured directly at ~100 points across the surface of the feather with a scanning laser Doppler vibrometer (SLDV), as a function of airspeed, Uair. Most feathers exhibited multiple discrete modes of flutter, which we classified into types including tip, trailing vane and torsional modes. Vibratory behavior within a given mode was usually stable, but changes in independent variables such as airspeed or orientation sometimes caused feathers to abruptly 'jump' from one mode to another. We measured structural resonance frequencies and mode shapes directly by measuring the free response of 64 feathers stimulated with a shaker and recorded with the SLDV. As predicted by the aeroelastic flutter hypothesis, the mode shape (spatial distribution) of flutter corresponded to a bending or torsional structural resonance frequency of the feather. However, the match between structural resonance mode and flutter mode was better for tip or torsional mode shapes, and poorer for trailing vane modes. Often, the 3rd bending structural harmonic matched the expressed mode of flutter, rather than the fundamental. We conclude that flutter occurs when airflow excites one or more structural resonance frequencies of a feather, most akin to a vibrating violin string.

  2. Real-time flutter analysis of an active flutter-suppression system on a remotely piloted research aircraft

    NASA Technical Reports Server (NTRS)

    Gilyard, G. B.; Edwards, J. W.

    1983-01-01

    Flight-test results of the first three flights of an aeroelastic research wing are described. The flight flutter-test technique used to obtain real-time damping estimates from fast-frequency sweep data was obtained and the open-loop flutter boundary determined. Nyquist analyses of sweep maneuvers appear to provide additional valuable information about flutter suppression system operation, both in terms of phase-margin estimates and as a means of evaluating maneuver quality. An error in implementing the flutter-suppression system required in a one-half nominal gain configuration, which caused the wing to be unstable at lower Mach numbers than anticipated, and the vehicle experienced closed-loop flutter on its third flight. Real-time flutter-testing procedures were improved.

  3. Flutter spectral measurements using stationary pressure transducers

    NASA Technical Reports Server (NTRS)

    Kurkov, A. P.

    1980-01-01

    Engine-order sampling was used to eliminate the integral harmonics from the flutter spectra corresponding to a case-mounted static pressure transducer. Using the optical displacement data, it was demonstrated that the blade-order sampling of pressure data may yield erroneous results due to the interference caused by blade vibration. Two methods are presented which effectively eliminate this interference yielding the blade-pressure-difference spectra. The phase difference between the differential-pressure and the displacement spectra was evaluated.

  4. Model mount system for testing flutter

    NASA Technical Reports Server (NTRS)

    Farmer, M. G. (Inventor)

    1984-01-01

    A wind tunnel model mount system is disclosed for effectively and accurately determining the effects of attack and airstream velocity on a model airfoil or aircraft. The model mount system includes a rigid model attached to a splitter plate which is supported away from the wind tunnel wall several of flexible rods. Conventional instrumentation is employed to effect model rotation through a turntable and to record model flutter data as a function of the angle of attack versus dynamic pressure.

  5. A historical overview of flight flutter testing

    NASA Technical Reports Server (NTRS)

    Kehoe, Michael W.

    1995-01-01

    This paper reviews the test techniques developed over the last several decades for flight flutter testing of aircraft. Structural excitation systems, instrumentation systems, digital data preprocessing, and parameter identification algorithms (for frequency and damping estimates from the response data) are described. Practical experiences and example test programs illustrate the combined, integrated effectiveness of the various approaches used. Finally, comments regarding the direction of future developments and needs are presented.

  6. Supersonic Chordwise Bending Flutter in Cascades

    DTIC Science & Technology

    1975-05-31

    such a flutter boundary can be made by utilizing the trend lines predicted from a supersonic analysis based on supersonic cascade theory (Appendix I...bonding agent was injected via hypodermic needles after the blade tabs were properly inserted, The integrity and repeatability of the mounting of the indi...in conjunction with NASTRAN predictions and supersonic cascade aerodynamic computa- tions. Comparisons between theory and experiment are discussed. DD

  7. YF-16 flight flutter test procedures

    NASA Technical Reports Server (NTRS)

    Brignac, W. J.; Ness, H. B.; Johnson, M. K.; Smith, L. M.

    1976-01-01

    The Random Decrement technique (Randomdec) was incorporated in procedures for flight testing of the YF-16 lightweight fighter prototype. Damping values obtained substantiate the adequacy of the flutter margin of safety. To confirm the structural modes which were being excited, a spectral analysis of each channel was performed using the AFFTC time/data 1923/50 time series analyzer. Inflight test procedure included the careful monitoring of strip charts, three axis pulses, rolls, and pullups.

  8. Mechanism of Flutter A Theoretical and Experimental Investigation of the Flutter Problem

    NASA Technical Reports Server (NTRS)

    Theodorsen, Theodore; Garrick, I E

    1940-01-01

    The results of the basic flutter theory originally devised in 1934 and published as NACA Technical Report no. 496 are presented in a simpler and more complete form convenient for further studies. The paper attempts to facilitate the judgement of flutter problems by a systematic survey of the theoretical effects of the various parameters. A large number of experiments were conducted on cantilever wings, with and without ailerons, in the NACA high-speed wind tunnel for the purpose of verifying the theory and to study its adaptability to three-dimensional problems. The experiments included studies on wing taper ratios, nacelles, attached floats, and external bracings. The essential effects in the transition to the three-dimensional problem have been established. Of particular interest is the existence of specific flutter modes as distinguished from ordinary vibration modes. It is shown that there exists a remarkable agreement between theoretical and experimental results.

  9. Management of atrial fibrillation.

    PubMed

    Moukabary, Talal; Gonzalez, Mario D

    2015-07-01

    Atrial fibrillation is a very common clinical problem with a high prevalence that is expected to rise over time because of increasing risk factors (eg, age, obesity, hypertension). This high prevalence is also associated with high cost, because atrial fibrillation represents about 1% of overall health care spending. The management of atrial fibrillation involves multiple facets: (1) management of underlying disease if present and the management of atrial fibrillation risk factors, (2) prevention of thromboembolism, (3) control of the ventricular rate during atrial fibrillation, and (4) restoration and maintenance of normal sinus rhythm.

  10. Flutter Analysis for Turbomachinery Using Volterra Series

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing; Yao, Weigang

    2014-01-01

    The objective of this paper is to describe an accurate and efficient reduced order modeling method for aeroelastic (AE) analysis and for determining the flutter boundary. Without losing accuracy, we develop a reduced order model based on the Volterra series to achieve significant savings in computational cost. The aerodynamic force is provided by a high-fidelity solution from the Reynolds-averaged Navier-Stokes (RANS) equations; the structural mode shapes are determined from the finite element analysis. The fluid-structure coupling is then modeled by the state-space formulation with the structural displacement as input and the aerodynamic force as output, which in turn acts as an external force to the aeroelastic displacement equation for providing the structural deformation. NASA's rotor 67 blade is used to study its aeroelastic characteristics under the designated operating condition. First, the CFD results are validated against measured data available for the steady state condition. Then, the accuracy of the developed reduced order model is compared with the full-order solutions. Finally the aeroelastic solutions of the blade are computed and a flutter boundary is identified, suggesting that the rotor, with the material property chosen for the study, is structurally stable at the operating condition, free of encountering flutter.

  11. [Current state of treatment strategies for atrial fibrillation].

    PubMed

    Rogge, C; Hilbert, S; Dagres, N; Hindricks, G

    2016-05-01

    Atrial fibrillation is the most common form of persistent cardiac arrhythmia with a greatly increasing prevalence due to an aging population and increasing cardiovascular risk factors. Apart from impairment of the quality of life atrial fibrillation is associated with a high morbidity, most importantly stroke and heart failure. The therapy is complex and aims at improving symptoms as well as the prevention of thromboembolic complications, heart failure and aggravating comorbidities. Based on individual patient characteristics and symptoms therapy is mainly based on heart rate control by pharmacological means or therapy for maintaining sinus rhythm. This treatment includes antiarrhythmic drugs and catheter ablation. Current research is aimed at the investigation of the electrophysiological mechanisms of recurrent therapy refractive atrial fibrillation and the question whether the maintenance of sinus rhythm can improve the prognosis of atrial fibrillation.

  12. Atrial fibrillation management: evaluating rate vs rhythm control.

    PubMed

    Nguyen, Tuan; Jolly, Umjeet; Sidhu, Kiran; Yee, Raymond; Leong-Sit, Peter

    2016-06-01

    Atrial fibrillation (AF) is an increasing global issue leading to increased hospitalizations, adverse health related events and mortality. This review focuses on the management of atrial fibrillation, in particular in the past decade, comparing two major strategies, rate or rhythm control. We evaluate the evidence for each strategy, pharmacological options and the increasing utilization of invasive techniques, in particular catheter ablation and use of implantable cardiac pacing devices. Pharmacological comparative trials evaluating both strategies have shown rate control being non-inferior to rhythm control for clinical outcomes of mortality and other cardiovascular events (including stroke). Catheter ablation techniques, involving radiofrequency ablation and recently cryoablation, have shown promising results in particular with paroxysmal AF. However, persistent AF provides ongoing challenges and will be a particular focus of continued research.

  13. Relation of porphyria to atrial fibrillation.

    PubMed

    Dhoble, Abhijeet; Patel, Mehul B; Abdelmoneim, Sahar S; Puttarajappa, Chethan; Abela, George S; Bhatt, Deepak L; Thakur, Ranjan K

    2009-08-01

    Porphyrias are a group of inherited disorders affecting enzymes in the heme biosynthesis pathway, leading to overproduction and/or accumulation of porphyrin or its precursors. Porphyrias have been associated with autonomic dysfunction, which in turn can develop atrial fibrillation (AF). The purpose of this study was to characterize the prevalence of AF and atrial flutter (AFl) in patients with porphyrias. A single-center retrospective cohort study was designed using data from chart reviews of patients who were admitted to the hospital from January 2000 to June 2008. Fifty-six distinct cases were found with a discharge diagnosis of porphyria including all its subtypes. From the same database, age- and gender-matched controls were identified using computer-generated random numbers. We selected 1 age- and gender-matched control for each case. Electrocardiograms and echocardiograms were reviewed by 2 independent reviewers. Only patients with available 12-lead electrocardiograms that showed AF/AFl were labeled with that diagnosis. All patients with a diagnosis of porphyria were included in the study irrespective of their age. Seven of 56 patients with porphyria met inclusion criteria, yielding a prevalence of AF/AFl of 12.5%. This association was significant (p = 0.028, relative risk 7.45, 95% confidence interval 1.01 to 66.14) compared with the age- and gender-matched control group (2%). In conclusion, our observations suggest that porphyria may be significantly associated with AF/AFl.

  14. Splanchnectopia Accompanied With Atrial Septal Defect: A Case Report

    PubMed Central

    Bao, Ning; Zhang, Yu

    2011-01-01

    Splanchnetopia accompanied with atrial septal defect is a rare congenital malformation clinically. Recent studies show that the patients are susceptible to lung disease. We present a case of a 62-year-old man who presented to our hospital with cough, palpitation and short of breath after activity. On physical examination, we found cyanosis of lips and face, swollen jugular vein, bubble sounds at the lung bottom, irregular heart rhythm, the large liver under the left rib and the lower limbs edema. Laboratory studies revealed white blood cell 18.6 × 109/L and neutrophils 73.9%. Electrocardiogram showed disappearance of P wave and substituted F wave with irregular R-R interval. Ultrasound cardiogram indicated that there was a 24 mm-long gap in the middle of the atrial septal. Dextrocardia, pulmonary artery extrudes and infection of lung were found by chest x-ray. The abdomen ultrasound indicated organ flip. Clinical diagnosis was congenital heart disease, splanchnectopia, atrial septal defect, Eisenmenger’s syndrome, atrial flutter, cardiac function class III and pneumonia. The patient left hospital after 2-week treatment. Its clinical significance is when the thoracic and celiac organs are ill, the position of the symptoms and physical signs are contrary to the normal place. Therefore, we should make a careful and systematic examination of the patients in order to avoid misdiagnosis and delay in treatment.

  15. Managing atrial fibrillation in the elderly: critical appraisal of dronedarone.

    PubMed

    Trigo, Paula; Fischer, Gregory W

    2012-01-01

    Atrial fibrillation is the most commonly seen arrhythmia in the geriatric population and is associated with increased cardiovascular morbidity and mortality. Treatment of the elderly with atrial fibrillation remains challenging for physicians, because this unique subpopulation is characterized by multiple comorbidities requiring chronic use of numerous medications, which can potentially lead to severe drug interactions. Furthermore, age-related changes in the cardiovascular system as well as other physiological changes result in altered drug pharmacokinetics. Dronedarone is a new drug recently approved for the treatment of arrhythmias, such as atrial fibrillation and/or atrial flutter. Dronedarone is a benzofuran amiodarone analog which lacks the iodine moiety and contains a methane sulfonyl group that decreases its lipophilicity. These differences in chemical structure are responsible for making dronedarone less toxic than amiodarone which, in turn, results in fewer side effects. Adverse events for dronedarone include gastrointestinal side effects and rash. No dosage adjustments are required for patients with renal impairment. However, the use of dronedarone is contraindicated in the presence of severe hepatic dysfunction.

  16. Staged transthoracic approach to persistent atrial fibrillation (TOP-AF): study protocol for a randomized trial

    PubMed Central

    2014-01-01

    Background Persistent atrial fibrillation frequently shows multiple different electrophysiological mechanisms of induction. This heterogeneity causes a low success rate of single procedures of ablation and a high incidence of recurrence. Surgical ablation through bilateral thoracotomy demonstrates better results after a single procedure. Prospective observational studies in inhomogeneous populations without control groups report a remarkable 90% of success with hybrid or staged procedures of surgical ablation coupled with catheter ablation. In this trial, we will examine the hypothesis that a staged approach involving initial minimally invasive surgical ablation of persistent atrial fibrillation, followed by a second percutaneous procedure in case of recurrence, has a higher success rate than repeated percutaneous procedures. Methods/Design This is a controlled (2:1) randomized trial comparing use of a percutaneous catheter with minimally invasive transthoracic surgical ablation of persistent atrial fibrillation. The inclusion and exclusion criteria, definitions, and treatment protocols are those reported by the 2012 Expert Consensus Statement on catheter and surgical ablation of atrial fibrillation. Patients will be randomized to either percutaneous catheter (n = 100) or surgical (n = 50) ablation as the first procedure. After 3 months, they are re-evaluated, according to the same guidelines, and receive a second procedure if necessary. Crossover will be allowed and data analyzed on an “intention-to-treat” basis. Primary outcomes are the incidence of sinus rhythm at 6 and 12 months and the proportions of patients requiring a second procedure. Discussion The use of a staged strategy combining surgical and percutaneous approaches might be more favorable in treatment of persistent atrial fibrillation than the controversial single percutaneous ablation. Trial registration ISRCTN08035058 Reg 06.20.2013 PMID:24885377

  17. Prediction of early-onset atrial tachyarrhythmia after successful trans-catheter device closure of atrial septal defect

    PubMed Central

    Park, Kyoung-Min; Hwang, Jin Kyung; Chun, Kwang Jin; Park, Seung-Jung; On, Young Keun; Kim, June Soo; Park, Seung Woo; Kang, I-Seok; Song, Jinyoung; Huh, June

    2016-01-01

    Abstract Atrial tachyarrhythmia is a well-known long-term complication of atrial septal defect (ASD) in adults, even after successful trans-catheter closure. However, the risk factors for early-onset atrial tachyarrhythmia after trans-catheter closure remain unclear. This retrospective study enrolled adults with secundum ASD undergoing trans-catheter closure from January 2000 to March 2014. We analyzed the clinical characteristics of patients and assessed risk factors for new-onset atrial tachyarrhythmia defined as a composite of atrial fibrillation or flutter (AF/AFL) after ASD closure. We enrolled a total of 427 patients; 123 were male (28.8%) and the median age was 37.0 (interquartile range [IQR]: 18.3–49.0). Nineteen (4.4%) patients had documented atrial tachyarrhythmia during the follow-up period (median: 11.4 months [IQR: 5.4–24]). Patients with transient AF/AFL during closure showed a greater incidence of new-onset atrial tachyarrhythmia during the follow-up period than patients with consistent sinus rhythm during closure (27.3% vs 3.8%; P = 0.01). Most new-onset atrial tachyarrhythmias were documented within 6 months (median: 2.6 [IQR: 1.2–4.1] months) of closure. In the multivariate analysis, the risk for new-onset atrial tachyarrhythmia was significant in patients with AF/AFL during closure (hazard ratio [HR]: 9.90, 95% confidence interval [CI]: 2.86–34.20; P < 0.001), deficient posteroinferior rim (HR: 5.48, 95% CI: 1.15–25.72; P = 0.04), and age of closure over 48 years (HR: 3.30, 95% CI: 1.30–8.38; P = 0.01). In conclusion, transient AF/AFL during trans-catheter closure of ASD as well as deficient posteroinferior rim and age of closure over 48 years may be useful for predicting early new-onset atrial tachyarrhythmia after device closure. PMID:27583905

  18. Low energy transvenous cardioversion of short duration atrial tachyarrhythmias in humans using a single lead system.

    PubMed

    Heisel, A; Jung, J; Fries, R; Stopp, M; Sen, S; Schieffer, H; Ozbek, C

    1997-01-01

    The purpose of this study was to investigate the efficacy and safety of atrial cardioversion using an endocardial single lead system presently used for ventricular defibrillation. The study population consisted of 26 recipients of an ICD in combination with a conventional endocardial single lead system with the proximal spring electrode as anode in the SVC and the distal as cathode in the apex of the RV. Atrial tachyarrhythmias were induced by right atrial burst pacing. If the arrhythmia sustained > 1 minute, biphasic shocks synchronized with the R wave were delivered using the implanted device, beginning with an energy of 4 J. If 4 J failed to terminate the arrhythmia, energy was increased stepwise, if the first shock was successful, a step-down testing was performed after reinduction of atrial tachyarrhythmias. The mean atrial defibrillation threshold was 2.3 +/- 1.2 J (range, 0.5-5 J). A total of 154 shocks were delivered and no adverse effects were observed. The mean defibrillation threshold for atrial flutter was somewhat lower than that for AF (1.8 +/- 1 J vs 2.7 +/- 1.4 J, P = 0.08). There was no correlation between the atrial defibrillation threshold and a history of previously occurring atrial tachyarrhythmias, the kind of the underlying heart disease, a prescription of antiarrhythmic drugs, the dimension of the LA, the LVEF, or the ventricular DFT. Internal atrial cardioversion of short duration atrial tachyarrhythmias using a transvenous single lead system designed for ventricular defibrillation is feasible and safe at low energies, and may have important clinical applications.

  19. Thermal ablation.

    PubMed

    Webb, Heather; Lubner, Meghan G; Hinshaw, J Louis

    2011-04-01

    Image-guided tumor ablation refers to a group of treatment modalities that have emerged during the past 2 decades as important tools in the treatment of a wide range of tumors throughout the body. Although most widely recognized in the treatment of hepatic and renal malignancies, the role of thermal ablation has expanded to include lesions of the lung, breast, prostate, bone, as well as other organs and its clinical applications continue to increase. In the following article, we discuss the major thermal ablation modalities, their respective strengths and weaknesses, potential complications and how to avoid them, as well as possible future applications.

  20. Distinct contractile and molecular differences between two goat models of atrial dysfunction: AV block-induced atrial dilatation and atrial fibrillation.

    PubMed

    Greiser, Maura; Neuberger, Hans-Ruprecht; Harks, Erik; El-Armouche, Ali; Boknik, Peter; de Haan, Sunniva; Verheyen, Fons; Verheule, Sander; Schmitz, Wilhelm; Ravens, Ursula; Nattel, Stanley; Allessie, Maurits A; Dobrev, Dobromir; Schotten, Ulrich

    2009-03-01

    Atrial dilatation is an independent risk factor for thromboembolism in patients with and without atrial fibrillation (AF). In many patients, atrial dilatation goes along with depressed contractile function of the dilated atria. While some mechanisms causing atrial contractile dysfunction in fibrillating atria have been addressed previously, the cellular and molecular mechanisms of atrial contractile remodeling in dilated atria are unknown. This study characterized in vivo atrial contractile function in a goat model of atrial dilatation and compared it to a goat model of AF. Differences in the underlying mechanisms were elucidated by studying contractile function, electrophysiology and sarcoplasmic reticulum (SR) Ca2+ load in atrial muscle bundles and by analyzing expression and phosphorylation levels of key Ca2+-handling proteins, myofilaments and the expression and activity of their upstream regulators. In 7 chronically instrumented, awake goats atrial contractile dysfunction was monitored during 3 weeks of progressive atrial dilatation after AV-node ablation (AV block goats (AVB)). In open chest experiments atrial work index (AWI) and refractoriness were measured (10 goats with AVB, 5 goats with ten days of AF induced by repetitive atrial burst pacing (AF), 10 controls). Isometric force of contraction (FC), transmembrane action potentials (APs) and rapid cooling contractures (RCC, a measure of SR Ca2+ load) were studied in right atrial muscle bundles. Total and phosphorylated Ca2+-handling and myofilament protein levels were quantified by Western blot. In AVB goats, atrial size increased by 18% (from 26.6+/-4.4 to 31.6+/-5.5 mm, n=7 p<0.01) while atrial fractional shortening (AFS) decreased (from 18.4+/-1.7 to 12.8+/-4.0% at 400 ms, n=7, p<0.01). In open chest experiments, AWI was reduced in AVB and in AF goats compared to controls (at 400 ms: 8.4+/-0.9, n=7, and 3.2+/-1.8, n=5, vs 18.9+/-5.3 mmxmmHg, n=7, respectively, p<0.05 vs control). FC of isolated right

  1. Patient-induced complications of a Heimlich flutter valve.

    PubMed

    Crocker, H L; Ruffin, R E

    1998-03-01

    Heimlich flutter valves have gained widespread acceptance in the treatment of pneumothorax. However, some features of their design may predispose them to inadvertent misuse. A case of tension pneumothorax is described which resulted from the insertion of a drinking straw into the Heimlich flutter valve assembly.

  2. NASTRAN documentation for flutter analysis of advanced turbopropellers

    NASA Technical Reports Server (NTRS)

    Elchuri, V.; Gallo, A. M.; Skalski, S. C.

    1982-01-01

    An existing capability developed to conduct modal flutter analysis of tuned bladed-shrouded discs was modified to facilitate investigation of the subsonic unstalled flutter characteristics of advanced turbopropellers. The modifications pertain to the inclusion of oscillatory modal aerodynamic loads of blades with large (backward and forward) varying sweep.

  3. Active controls for flutter suppression and gust alleviation in supersonic aircraft. [YF-17 flutter model

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1980-01-01

    Results of work done on active controls on the modified YF-17 flutter model are summarized. The basic derivation of a suitable control law is discussed. It is shown that discrepencies found between analysis and wind tunnel tests originate from the lack of proper implementation of the desired control law. Program capabilities are described.

  4. How Is Atrial Fibrillation Treated?

    MedlinePlus

    ... from the NHLBI on Twitter. How Is Atrial Fibrillation Treated? Treatment for atrial fibrillation (AF) depends on ... much thyroid hormone). Who Needs Treatment for Atrial Fibrillation? People who have AF but don't have ...

  5. Preliminary study of effects of winglets on wing flutter

    NASA Technical Reports Server (NTRS)

    Doggett, R. V., Jr.; Farmer, M. G.

    1976-01-01

    Some experimental flutter results are presented over a Mach number range from about 0.70 to 0.95 for a simple, swept, tapered, flat-plate wing model having a planform representative of subsonic transport airplanes and for the same wing model equipped with two different upper surface winglets. Both winglets had the same planform and area (about 2 percent of the basic-wing area); however, one weighed about 0.3 percent of the basic-wing weight, and the other weighed about 1.8 percent of the wing weight. The addition of the lighter winglet reduced the wing-flutter dynamic pressure by about 3 percent; the heavier winglet reduced the wing-flutter dynamic pressure by about 12 percent. The experimental flutter results are compared at a Mach number of 0.80 with analytical flutter results obtained by using doublet-lattice and lifting-surface (kernel-function) unsteady aerodynamic theories.

  6. Optical detection of blade flutter. [in YF-100 turbofan engine

    NASA Technical Reports Server (NTRS)

    Nieberding, W. C.; Pollack, J. L.

    1977-01-01

    The paper examines the capabilities of photoelectric scanning (PES) and stroboscopic imagery (SI) as optical monitoring tools for detection of the onset of flutter in the fan blades of an aircraft gas turbine engine. Both optical techniques give visual data in real time as well as video-tape records. PES is shown to be an ideal flutter monitor, since a single cathode ray tube displays the behavior of all the blades in a stage simultaneously. Operation of the SI system continuously while searching for a flutter condition imposes severe demands on the flash tube and affects its reliability, thus limiting its use as a flutter monitor. A better method of operation is to search for flutter with the PES and limit the use of SI to those times when the PES indicates interesting blade activity.

  7. Experimental transonic flutter characteristics of supersonic cruise configurations

    NASA Technical Reports Server (NTRS)

    Durham, Michael H.; Cole, Stanley R.; Cazier, F. W., Jr.; Keller, Donald F.; Parker, Ellen C.; Wilkie, W. Keats

    1990-01-01

    The flutter characteristics of a generic arrow-wing supersonic transport configuration are studied. The wing configuration has a 3 percent biconvex airfoil and a leading-edge sweep of 73 deg out to a cranked tip with a 60 deg leading-edge sweep. The ground vibration tests and flutter test procedure are described. The effects of flutter on engine nacelles, fuel loading, wing-mounted vertical fin, wing angle-of-attack, and wing tip mass and stiffness distributions are analyzed. The data reveal that engine nacelles reduce the transonic flutter dynamic pressure by 25-30 percent; fuel loadings decrease dynamic pressures by 25 percent; 4-6 deg wing angles-of-attack cause steep transonic boundaries; and 5-10 percent changes in flutter dynamic pressures are the result of the wing-mounted vertical fin and wing-tip mass and stiffness distributions.

  8. Panel Flutter and Sonic Fatigue Analysis for RLV

    NASA Technical Reports Server (NTRS)

    Mei, Chuh; Cheng, Guangfeng

    2001-01-01

    A methodology is presented for the flutter analysis of the seal of thermal protection system (TPS) panel of X-33 Advanced Technology Demonstrator test vehicle. The seal is simulated as a two-dimensional cantilevered panel with an elastic stopper, which is modeled as an equivalent spring. This cantilever beam-spring model under the aerodynamic pressure at supersonic speeds turns out to be an impact nonlinear dynamic system. The flutter analysis of the seal is thus carried out using, time domain numerical simulation with a displacement stability criterion. The flutter boundary of the seal is further verified with a family of three traditional and one nontraditional panel flutter models. The frequency domain method that applies eigenanalysis on the traditional panel flutter problem was used. The results showed that the critical dynamic pressure could be more than doubled with properly chosen material for the base stopper. The proposed methodology can be easily extended to three-dimensional panel seals with flow angularity.

  9. Catheter Ablation

    MedlinePlus

    ... you during the procedure. Machines will measure your heart’s activity. All types of ablation require cardiac catheterization to place flexible tubes, or catheters, inside your heart to make the scars. Your doctor will clean ...

  10. Real-time flutter analysis of an active flutter-suppression system on a remotely piloted research aircraft

    NASA Technical Reports Server (NTRS)

    Gilyard, G. B.; Edwards, J. W.

    1983-01-01

    Flight flutter-test results of the first aeroelastic research wing (ARW-1) of NASA's drones for aerodynamic and structural testing program are presented. The flight-test operation and the implementation of the active flutter-suppression system are described as well as the software techniques used to obtain real-time damping estimates and the actual flutter testing procedure. Real-time analysis of fast-frequency aileron excitation sweeps provided reliable damping estimates. The open-loop flutter boundary was well defined at two altitudes; a maximum Mach number of 0.91 was obtained. Both open-loop and closed-loop data were of exceptionally high quality. Although the flutter-suppression system provided augmented damping at speeds below the flutter boundary, an error in the implementation of the system resulted in the system being less stable than predicted. The vehicle encountered system-on flutter shortly after crossing the open-loop flutter boundary on the third flight and was lost. The aircraft was rebuilt. Changes made in real-time test techniques are included.

  11. Treatment of Chronic Atrial Fibrillation During Surgery for Rheumatic Mitral Valve Disease

    PubMed Central

    Gonçalves, Flavio Donizete; Leite, Valdir Gonçalves; Leite, Vanusa Gonçalves; Maia, Marcelo Alves; Gomes, Otoni Moreira; Lima, Melchior Luiz; Osterne, Evandro César Vidal; Kallás, Elias

    2016-01-01

    Introduction The result of surgical ablation of atrial fibrillation remains controversial, although prospective and randomized studies have shown significant differences in the return to sinus rhythm in patients treated with ablation versus control group. Surgery of the Labyrinth, proposed by Cox and colleagues, is complex and increases the morbidity rate. Therefore, studies are needed to confirm the impact on clinical outcomes and quality of life of these patients. Objective To analyze the results obtained in the treatment of atrial fibrillation by surgical approach, by Gomes procedure, for mitral valve surgery in patients with rheumatic heart disease associated with chronic atrial fibrillation. Methods We studied 20 patients with mitral valve dysfunction of rheumatic etiology, evolving with chronic atrial fibrillation, submitted to surgical treatment of valvular dysfunction and atrial fibrillation by Gomes procedure. Results The mean duration of infusion ranged from 65.8±11.22 and aortic clamping of 40.8±7.87 minutes. Of 20 patients operated, 19 (95%) patients were discharged with normal atrial heart rhythm. One (5%) patient required permanent endocardial pacing. In the postoperative follow-up of six months, 18 (90%) patients continued with regular atrial rhythm, one (5%) patient returned to atrial fibrillation and one (5%) patient continued to require endocardial pacemaker to maintain regular rhythm. Conclusion Gomes procedure associated with surgical correction of mitral dysfunction simplified the surgical ablation of atrial fibrillation in patients with rheumatic mitral valve disease and persistent atrial fibrillation. The results showed that it is a safe and effective procedure. PMID:27849305

  12. Unsteady aerodynamics of fluttering and tumbling plates

    NASA Astrophysics Data System (ADS)

    Andersen, A.; Pesavento, U.; Wang, Z. Jane

    2005-10-01

    We investigate the aerodynamics of freely falling plates in a quasi-two-dimensional flow at Reynolds number of 10(3) , which is typical for a leaf or business card falling in air. We quantify the trajectories experimentally using high-speed digital video at sufficient resolution to determine the instantaneous plate accelerations and thus to deduce the instantaneous fluid forces. We compare the measurements with direct numerical solutions of the two-dimensional Navier Stokes equation. Using inviscid theory as a guide, we decompose the fluid forces into contributions due to acceleration, translation, and rotation of the plate. For both fluttering and tumbling we find that the fluid circulation is dominated by a rotational term proportional to the angular velocity of the plate, as opposed to the translational velocity for a glider with fixed angle of attack. We find that the torque on a freely falling plate is small, i.e. the torque is one to two orders of magnitude smaller than the torque on a glider with fixed angle of attack. Based on these results we revise the existing ODE models of freely falling plates. We get access to different kinds of dynamics by exploring the phase diagram spanned by the Reynolds number, the dimensionless moment of inertia, and the thickness-to-width ratio. In agreement with previous experiments, we find fluttering, tumbling, and apparently chaotic motion. We further investigate the dependence on initial conditions and find brief transients followed by periodic fluttering described by simple harmonics and tumbling with a pronounced period-two structure. Near the cusp-like turning points, the plates elevate, a feature which would be absent if the lift depended on the translational velocity alone.

  13. Reduced prevalence of atrial fibrillation in black patients compared with white patients attending an urban hospital: an electrocardiographic study.

    PubMed Central

    Upshaw, Charles B.

    2002-01-01

    Electrocardiographic differences occur between African-American and white persons. The cardiac rhythms of 2123 African-American and white hospital patients from 20 through 99 years of age were studied in a consecutive manner. The prevalence of atrial fibrillation increases dramatically with advancing age in both African-American and white patients. The prevalence of atrial fibrillation begins to increase at age 60 years and continues to increase through the 10th decade of life, although the rate of rise of the prevalence of atrial fibrillation is less in African-American patients compared with white patients. The cause of the reduced prevalence of atrial fibrillation in African-American patients remains unexplained. Atrial fibrillation occurs in 2.5% of African-American patients compared with 7.8% of white patients attending an urban hospital. There is little difference in the prevalence of atrial fibrillation between men and women. Atrial fibrillation occurs nearly seven times more often than does atrial flutter. PMID:11995632

  14. Flutter analysis of low aspect ratio wings

    NASA Technical Reports Server (NTRS)

    Parnell, L. A.

    1986-01-01

    Several very low aspect ratio flat plate wing configurations are analyzed for their aerodynamic instability (flutter) characteristics. All of the wings investigated are delta planforms with clipped tips, made of aluminum alloy plate and cantilevered from the supporting vehicle body. Results of both subsonic and supersonic NASTRAN aeroelastic analyses as well as those from another version of the program implementing the supersonic linearized aerodynamic theory are presented. Results are selectively compared with the experimental data; however, supersonic predictions of the Mach Box method in NASTRAN are found to be erratic and erroneous, requiring the use of a separate program.

  15. Wavelet Applications for Flight Flutter Testing

    NASA Technical Reports Server (NTRS)

    Lind, Rick; Brenner, Marty; Freudinger, Lawrence C.

    1999-01-01

    Wavelets present a method for signal processing that may be useful for analyzing responses of dynamical systems. This paper describes several wavelet-based tools that have been developed to improve the efficiency of flight flutter testing. One of the tools uses correlation filtering to identify properties of several modes throughout a flight test for envelope expansion. Another tool uses features in time-frequency representations of responses to characterize nonlinearities in the system dynamics. A third tool uses modulus and phase information from a wavelet transform to estimate modal parameters that can be used to update a linear model and reduce conservatism in robust stability margins.

  16. Hypersonic panel flutter in a rarefied atmosphere

    NASA Technical Reports Server (NTRS)

    Resende, Hugo B.

    1993-01-01

    Panel flutter is a form of dynamic aeroelastic instability resulting from the interaction between motion of an aircraft structural panel and the aerodynamic loads exerted on that panel by air flowing past one of the faces. It differs from lifting surface flutter in the sense that it is not usually catastrophic, the panel's motion being limited by nonlinear membrane stresses produced by the transverse displacement. Above some critical airflow condition, the linear instability grows to a limit cycle . The present investigation studies panel flutter in an aerodynamic regime known as 'free molecule flow', wherein intermolecular collisions can be neglected and loads are caused by interactions between individual molecules and the bounding surface. After collision with the panel, molecules may be reflected specularly or reemitted in diffuse fashion. Two parameters characterize this process: the 'momentum accommodation coefficient', which is the fraction of the specularly reflected molecules; and the ratio between the panel temperature and that of the free airstream. This model is relevant to the case of hypersonic flight vehicles traveling at very high altitudes and especially for panels oriented parallel to the airstream or in the vehicle's lee. Under these conditions the aerodynamic shear stress turns out to be considerably larger than the surface pressures, and shear effects must be included in the model. This is accomplished by means of distributed longitudinal and bending loads. The former can cause the panel to buckle. In the example of a simply-supported panel, it turns out that the second mode of free vibration tends to dominate the flutter solution, which is carried out by a Galerkin analysis. Several parametric studies are presented. They include the effects of (1) temperature ratio; (2) momentum accommodation coefficient; (3) spring parameters, which are associated with how the panel is connected to adjacent structures; (4) a parameter which relates compressive

  17. Prevalence of left atrial abnormalities in atrial fibrillation versus normal sinus patients

    PubMed Central

    Ketai, Loren H; Teague, Shawn D; Rissing, Stacy M

    2016-01-01

    Background Atrial fibrillation (AF) may be the cause or sequela of left atrial abnormalities and variants. Purpose To determine the prevalence of left atrial (LA) abnormalities in AF patients compared to normal sinus rhythm (NSR) patients. Material and Methods We retrospectively reviewed 281 cardiac CT examinations from 2010 to 2012, excluding patients with prior pulmonary vein ablation, known coronary artery disease, prior coronary stent placement, or coronary artery bypass grafts. The first group consisted of 159 AF patients undergoing cardiac CT prior to pulmonary vein ablation and the second group consisted of 122 NSR patients evaluated with coronary CT angiography. Demographic data were collected. LA abnormalities were analyzed. Left atrial diameter was measured on an axial view. Results A total of 281 patients were included. The male gender has significantly higher prevalence of AF than female gender, P value <0.001. Patients with AF were significantly older (mean age, 57.4 years; standard deviation [SD], 11.8 years) than NSR patients (mean age, 53.4 years; SD, 13.6 years), P value, 0.01. The left atrial diameter was greater in the AF patients (mean diameter, 4.3 cm; SD, 0.82 cm) versus the NSR patients (3.4 cm; SD, 0.58 cm), P value, <0.0001. LA diverticulum was the most prevalent variant, occurring in 28.4% of the entire patient population followed by LA pouch, occurring in 24%. There was no significant between group differences in the prevalence of these or the remainder of the LA variants. Conclusion AF patients differed significantly from NSR patients in LA size, gender, and mean age. There was no statistical significance between the two groups with regard to the LA morphologic abnormalities other than size. PMID:27358747

  18. Atrial fibrillation - discharge

    MedlinePlus

    Auricular fibrillation - discharge; A-fib - discharge; AF - discharge; Afib - discharge ... been in the hospital because you have atrial fibrillation . This condition occurs when your heart beats faster ...

  19. First Case of Automatic His Potential Detection With a Novel Ultra High-density Electroanatomical Mapping System for AV Nodal Ablation

    PubMed Central

    Hilbert, Sebastian; Kosiuk, Jedrzej; John, Silke; Hindricks, Gerhard; Bollmann, Andreas

    2016-01-01

    A 74-year old was considered for atrioventricular (AV) nodal ablation in view of atrial fibrillation (AF) with poorly controlled ventricular rate despite being on amiodarone. Targeted AV nodal ablation was successfully performed after identifying the target site for ablation by reviewing an ultra high-density map of the His region produced by automatic electrogram annotation. PMID:25852249

  20. Non-invasive cardiac mapping in clinical practice: Application to the ablation of cardiac arrhythmias.

    PubMed

    Dubois, Rémi; Shah, Ashok J; Hocini, Mélèze; Denis, Arnaud; Derval, Nicolas; Cochet, Hubert; Sacher, Frédéric; Bear, Laura; Duchateau, Josselin; Jais, Pierre; Haissaguerre, Michel

    2015-01-01

    Ten years ago, electrocardiographic imaging (ECGI) started to demonstrate its efficiency in clinical settings. The initial application to localize focal ventricular arrhythmias such as ventricular premature beats was probably the easiest to challenge and validates the concept. Our clinical experience in using this non-invasive mapping technique to identify the sources of electrical disorders and guide catheter ablation of atrial arrhythmias (premature atrial beat, atrial tachycardia, atrial fibrillation), ventricular arrhythmias (premature ventricular beats) and ventricular pre-excitation (Wolff-Parkinson-White syndrome) is described here.

  1. Direct Pulmonary Vein Ablation with Stenosis Prevention Therapy

    PubMed Central

    DeSimone, Christopher V.; Holmes, David R.; Ebrille, Elisa; Syed, Faisal F.; Ladewig, Dorothy J.; Mikell, Susan B.; Powers, Joanne; Suddendorf, Scott H.; Gilles, Emily J.; Danielsen, Andrew J.; Hodge, David O.; Kapa, Suraj; Asirvatham, Samuel J.

    2015-01-01

    Introduction The dominant location of electrical triggers for initiating atrial fibrillation (AF) originates from the muscle sleeves inside pulmonary veins (PVs). Currently, radiofrequency ablation (RFA) is performed outside of the PVs to isolate, rather than directly ablate these tissues, due to the risk of intraluminal PV stenosis. Methods In 4 chronic canine experiments, we performed direct PV muscle sleeve RFA ± post-ablation drug-coated balloon (DCB) treatment with paclitaxel/everolimus. Of the 4 PVs, 2 PVs were ablated and treated with DCB, 1 PV was ablated without DCB treatment (positive control), and 1 PV was left as a negative control. Local electrograms were assessed in PVs for near-field signals and were targeted for ablation. After 12-14 weeks survival, PVs were interrogated for absence of near-field PV potentials, and each PV was assessed for stenosis. Results All canines survived the study period without cardiorespiratory complications, and remained ambulatory. In all canines, PVs that were ablated and treated with DCB remained without any significant intraluminal stenosis. In contrast, PVs that were ablated and not treated with DCB showed near or complete intraluminal stenosis. At terminal study, PV potentials remained undetectable. A blinded, histologic analysis demonstrated that ablated PVs without DCB treatment had extensive thrombus, fibrin, mineralization, and elastin disruption. Conclusion Our chronic canine data suggest that direct PV tissue ablation without subsequent stenosis is feasible with the use of post-ablation DCBs. PMID:26075706

  2. Cascade flutter analysis with transient response aerodynamics

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Mahajan, Aparajit J.; Keith, Theo G., Jr.; Stefko, George L.

    1991-01-01

    Two methods for calculating linear frequency domain aerodynamic coefficients from a time marching Full Potential cascade solver are developed and verified. In the first method, the Influence Coefficient, solutions to elemental problems are superposed to obtain the solutions for a cascade in which all blades are vibrating with a constant interblade phase angle. The elemental problem consists of a single blade in the cascade oscillating while the other blades remain stationary. In the second method, the Pulse Response, the response to the transient motion of a blade is used to calculate influence coefficients. This is done by calculating the Fourier Transforms of the blade motion and the response. Both methods are validated by comparison with the Harmonic Oscillation method and give accurate results. The aerodynamic coefficients obtained from these methods are used for frequency domain flutter calculations involving a typical section blade structural model. An eigenvalue problem is solved for each interblade phase angle mode and the eigenvalues are used to determine aeroelastic stability. Flutter calculations are performed for two examples over a range of subsonic Mach numbers.

  3. Unsteady Aerodynamic Model Tuning for Precise Flutter Prediction

    NASA Technical Reports Server (NTRS)

    Pak, Chan-Gi

    2011-01-01

    A simple method for an unsteady aerodynamic model tuning is proposed in this study. This method is based on the direct modification of the aerodynamic influence coefficient matrices. The aerostructures test wing 2 flight-test data is used to demonstrate the proposed model tuning method. The flutter speed margin computed using only the test validated structural dynamic model can be improved using the additional unsteady aerodynamic model tuning, and then the flutter speed margin requirement of 15 % in military specifications can apply towards the test validated aeroelastic model. In this study, unsteady aerodynamic model tunings are performed at two time invariant flight conditions, at Mach numbers of 0.390 and 0.456. When the Mach number for the unsteady model tuning approaches to the measured fluttering Mach number, 0.502, at the flight altitude of 9,837 ft, the estimated flutter speed is approached to the measured flutter speed at this altitude. The minimum flutter speed difference between the estimated and measured flutter speed is -.14 %.

  4. Experimental Classical Flutter Reesults of a Composite Advanced Turboprop Model

    NASA Technical Reports Server (NTRS)

    Mehmed, O.; Kaza, K. R. V.

    1986-01-01

    Experimental results are presented that show the effects of blade pitch angle and number of blades on classical flutter of a composite advanced turboprop (propfan) model. An increase in the number of blades on the rotor or the blade pitch angle is destablizing which shows an aerodynamic coupling or cascade effect between blades. The flutter came in suddenly and all blades vibrated at the same frequency but at different amplitudes and with a common predominant phase angle between consecutive blades. This further indicates aerodynamic coupling between blades. The flutter frequency was between the first two blade normal modes, signifying an aerodynamic coupling between the normal modes. Flutter was observed at all blade pitch angles from small to large angles-of-attack of the blades. A strong blade response occurred, for four blades at the two-per-revolution (2P) frequency, when the rotor speed was near the crossing of the flutter mode frequency and the 2P order line. This is because the damping is low near the flutter condition and the interblade phase angle of the flutter mode and the 2P response are the same.

  5. Interactive flutter analysis and parametric study for conceptual wing design

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek

    1995-01-01

    An interactive computer program was developed for wing flutter analysis in the conceptual design stage. The objective was to estimate the flutter instability boundary of a flexible cantilever wing, when well defined structural and aerodynamic data are not available, and then study the effect of change in Mach number, dynamic pressure, torsional frequency, sweep, mass ratio, aspect ratio, taper ratio, center of gravity, and pitch inertia, to guide the development of the concept. The software was developed on MathCad (trademark) platform for Macintosh, with integrated documentation, graphics, database and symbolic mathematics. The analysis method was based on nondimensional parametric plots of two primary flutter parameters, namely Regier number and Flutter number, with normalization factors based on torsional stiffness, sweep, mass ratio, aspect ratio, center of gravity location and pitch inertia radius of gyration. The plots were compiled in a Vaught Corporation report from a vast database of past experiments and wind tunnel tests. The computer program was utilized for flutter analysis of the outer wing of a Blended Wing Body concept, proposed by McDonnell Douglas Corporation. Using a set of assumed data, preliminary flutter boundary and flutter dynamic pressure variation with altitude, Mach number and torsional stiffness were determined.

  6. Left atrial strain: a new predictor of thrombotic risk and successful electrical cardioversion

    PubMed Central

    González-Alujas, Teresa; Valente, Filipa; Aranda, Carlos; Rodríguez-Palomares, José; Gutierrez, Laura; Maldonado, Giuliana; Galian, Laura; Teixidó, Gisela; Evangelista, Artur

    2016-01-01

    Background Left atrial deformation (LAD) parameters are new markers of atrial structural remodelling that seem to be affected in atrial fibrillation (AF) and atrial flutter (AFL). This study aimed to determine whether LAD can identify patients with a higher risk of thrombosis and unsuccessful electrical cardioversion (ECV). Methods Retrospective study including 56 patients with AF or AFL undergoing ECV, with previous transthoracic (TTE) and transoesophageal echocardiography (TEE) studies. Echocardiographic parameters analysed were as follows: left ventricle function, left atrium (LA) dimensions, LAD parameters (positive and negative strain peaks), left atrial appendage (LAA) filling and emptying velocities and the presence of thrombi. Strain values were analysed according to thrombotic risk and success of ECV. Results Lower mean values of peak-positive strain (PPS) in patients with prothrombotic velocities (<25 cm/s) and a higher incidence of thrombi in LAA were observed compared with those with normal velocities. Multivariate analysis revealed PPS normalised by LA maximum volume indexed by body surface area (BSA) to be associated with prothrombotic risk (odds ratio 0.000 (95% CI: 0.000–0.243), P 0.017), regardless of CHADs2VASC score. Peak-negative strain normalised by LA volumes indexed by BSA were associated with unsuccessful ECV. Conclusions Atrial deformation parameters identify AF and AFL patients with a high risk of thrombosis and unsuccessful ECV. Therefore, these new parameters should be included in anticoagulation management and rhythm vs rate control strategies. PMID:27249551

  7. Nodal recovery, dual pathway physiology, and concealed conduction determine complex AV dynamics in human atrial tachyarrhythmias.

    PubMed

    Masè, Michela; Glass, Leon; Disertori, Marcello; Ravelli, Flavia

    2012-11-15

    The genesis of complex ventricular rhythms during atrial tachyarrhythmias in humans is not fully understood. To clarify the dynamics of atrioventricular (AV) conduction in response to a regular high-rate atrial activation, 29 episodes of spontaneous or pacing-induced atrial flutter (AFL), covering a wide range of atrial rates (cycle lengths from 145 to 270 ms), were analyzed in 10 patients. AV patterns were identified by applying firing sequence and surrogate data analysis to atrial and ventricular activation series, whereas modular simulation with a difference-equation AV node model was used to correlate the patterns with specific nodal properties. AV node response at high atrial rate was characterized by 1) AV patterns of decreasing conduction ratios at the shortening of atrial cycle length (from 236.3 ± 32.4 to 172.6 ± 17.8 ms) according to a Farey sequence ordering (conduction ratio from 0.34 ± 0.12 to 0.23 ± 0.06; P < 0.01); 2) the appearance of high-order alternating Wenckebach rhythms, such as 6:2, 10:2, and 12:2, associated with ventricular interval oscillations of large amplitude (407.7 ± 150.4 ms); and 3) the deterioration of pattern stability at advanced levels of block, with the percentage of stable patterns decreasing from 64.3 ± 35.2% to 28.3 ± 34.5% (P < 0.01). Simulations suggested these patterns to originate from the combined effect of nodal recovery, dual pathway physiology, and concealed conduction. These results indicate that intrinsic nodal properties may account for the wide spectrum of AV block patterns occurring during regular atrial tachyarrhythmias. The characterization of AV nodal function during different AFL forms constitutes an intermediate step toward the understanding of complex ventricular rhythms during atrial fibrillation.

  8. A multiple ion channel blocker, NIP-142, for the treatment of atrial fibrillation.

    PubMed

    Tanaka, Hikaru; Hashimoto, Norio

    2007-01-01

    Atrial fibrillation (AF) is one of the most frequent cardiac arrhythmia and is associated with increased cardiovascular morbidity and mortality, and the risk of stroke. Although currently available antiarrhythmic drugs are moderately effective in restoring normal sinus rhythm in patients with AF, excessive delay of ventricular repolarization by these agents may be associated with increased risk of proarrhythmia. Therefore, selective blockers of cardiac ion channel(s) that are exclusively present in the atria are highly desirable. NIP-142 is a novel benzopyrane derivative, which blocks potassium, calcium, and sodium channels and shows atrial specific action potential duration prolongation. NIP-142 preferentially blocks the ultrarapid delayed rectifier potassium current (I Kur) and the acetylcholine-activated potassium current (I KACh). Since I Kur and I KACh have been shown to be expressed more abundantly in the atrial than in the ventricular myocardium, the atrial-specific repolarization prolonging effect of NIP-142 is considered to be due to the blockade of these potassium currents. In canine models, NIP-142 was shown to terminate the microreentry type AF induced by vagal nerve stimulation and the macroreentry type atrial flutter induced by an intercaval crush. These effects of NIP-142 have been attributed to the prolongation of atrial effective refractory period (ERP), because this compound prolonged atrial ERP without affecting intraatrial and interatrial conduction times in these models. The ERP prolongation by NIP-142 was greater in the atrium than in the ventricle. NIP-142 also terminated the focal activity type AF induced by aconitine. In addition, NIP-142 reversed the atrial ERP shortening and the loss of rate adaptation induced by short-term rapid atrial pacing in anesthetized dogs. Thus, although clinical trials are required to provide evidence for its efficacy and safety, the novel multiple ion channel blocker, NIP-142, appears to be a useful agent for

  9. Flutter estimation of S-520 sounding rocket fins

    NASA Astrophysics Data System (ADS)

    Honda, Masahisa; Onoda, Junjiro; Onojima, Noboru; Nakada, Atsushi; Isogai, Koji

    The flutter margin of the fins, which has been improved for S-520 sounding rocket of ISAS, is estimated by wind tunnel tests and numerical flutter analysis. Both methods require stiffness distribution of the fin. In this paper, a new approach of fitting of FEM model to the measured matrix of influence coefficient is applied in order to eliminate the errors in the measured stiffness data, which may otherwise make the mathematical model nonpositive definite. The results of the wind tunnel tests and numerical flutter analysis using the above fitted FEM model stiffness distribution are compared and discussed.

  10. Stochastic Characterization of Flutter using Historical Wind Tunnel Data

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer

    2007-01-01

    Methods for predicting the onset of flutter during an experiment are traditionally applied treating the data as deterministic values. Uncertainty and variation in the data is often glossed over by using best-fit curves to represent the information. This paper applies stochastic treatments to wind tunnel data obtained for the Piezoelectric Aeroelastic Response Tailoring Investigation model. These methods include modal amplitude tracking, modal frequency tracking and several applications of the flutter margin method. The flutter margin method was developed by Zimmerman and Weissenburger, and extended by Poirel, Dunn and Porter to incorporate uncertainty. Much of the current work follows the future work recommendations of Poirel, Dunn and Porter.

  11. Distinct pharmacologic substrate in lidocaine-sensitive, repetitive atrial tachycardia.

    PubMed

    Chiale, Pablo A; Faivelis, Luciano; Garro, Hugo A; Fernández, Pablo A; Herrera Paz, Juan J; Elizari, Marcelo V

    2012-06-01

    Lidocaine-sensitive, repetitive atrial tachycardia is an uncommon arrhythmia. The electrophysiologic substrate is still unknown, and the pharmacologic responses have not been fully explored. The aim of this study was to investigate the effects of intravenous adenosine and verapamil in patients with lidocaine-sensitive atrial tachycardia. In 9 patients with repetitive uniform atrial tachycardia, the response to intravenous adenosine (12 mg), lidocaine (1 mg/kg body weight), and verapamil (10 mg) were sequentially investigated. Simultaneous 12-lead electrocardiogram (ECG) was recorded at baseline and continuously monitored thereafter. Tracings were obtained at regularly timed intervals right after the administration of each drug to evaluate changes in the arrhythmia characteristics. Repetitive atrial tachycardia was abolished by intravenous lidocaine in the 9 patients within the first 2 minutes after the end of injection. Adenosine suppressed the arrhythmia in 2 patients and shortened the runs of atrial ectopic activity in 1 patient, while verapamil was effective in 2 patients, 1 of them insensitive to adenosine and the other 1 sensitive to this agent. In 5 patients, the arrhythmia was abolished by radiofrequency ablation at different sites of the right atrium. Lidocaine-sensitive atrial tachycardia may eventually be also suppressed by adenosine and/or verapamil. This suggests that this enigmatic arrhythmia may be caused by different underlying electrophysiologic substrates and that at least in some cases, delayed afterdepolarizations seem to play a determining role.

  12. Focal para-hisian atrial tachycardia with dual exits

    PubMed Central

    Lawrance Jesuraj, M.; Sharada, K.; Sridevi, C.; Narasimhan, C.

    2013-01-01

    Focal atrial tachycardias (AT) in the right atrium (RA) tend to cluster around the crista terminalis, coronary sinus (CS) region, tricuspid annulus, and para-hisian region. In most cases, the AT focus can be identified by careful activation mapping, and completely eliminated by radiofrequency (RF) catheter ablation. However, RF ablation near the His bundle (HB) carries a risk of inadvertent damage to the atrioventricular (AV) conduction system. Here we describe a patient with an AT originating in the vicinity of the AV node, which was successfully ablated earlier from non-coronary aortic cusp (NCC), and recurred with an exit from para-hisian location. Respiratory excursions of the catheter were associated with migration to the area of HIs. This was successfully ablated during controlled apnoea, using 3D electroanatomic mapping. PMID:23993015

  13. Left Atrial Appendage Exclusion for Atrial Fibrillation

    PubMed Central

    Syed, Faisal F.; DeSimone, Christopher V.; Friedman, Paul A.; Asirvatham, Samuel J.

    2015-01-01

    SYNOPSIS Percutaneous left atrial appendage (LAA) closure is increasingly being used as a treatment strategy to prevent stroke in patients with atrial fibrillation (AF) who have contraindications to anticoagulants. A number of approaches and devices have been developed in the last few years, each with their own unique set of advantages and disadvantages. We review the published studies on surgical and percutaneous approaches to LAA closure; focusing on stroke mechanisms in AF, LAA structure and function relevant to stroke prevention, practical differences in procedural approach, and clinical considerations surrounding management. PMID:25443240

  14. Design and experimental validation of a flutter suppression controller for the active flexible wing

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.; Srinathkumar, S.

    1992-01-01

    The synthesis and experimental validation of an active flutter suppression controller for the Active Flexible Wing wind tunnel model is presented. The design is accomplished with traditional root locus and Nyquist methods using interactive computer graphics tools and extensive simulation based analysis. The design approach uses a fundamental understanding of the flutter mechanism to formulate a simple controller structure to meet stringent design specifications. Experimentally, the flutter suppression controller succeeded in simultaneous suppression of two flutter modes, significantly increasing the flutter dynamic pressure despite modeling errors in predicted flutter dynamic pressure and flutter frequency. The flutter suppression controller was also successfully operated in combination with another controller to perform flutter suppression during rapid rolling maneuvers.

  15. Ethanol Infusion in the Vein of Marshall in a Patient with Persistent Atrial Fibrillation

    PubMed Central

    Choi, Jah Yeon; Park, Eun Jin; Kim, Hee Dong; Park, Sung Hun; Song, Ji Young; Lee, Dae In; Shim, Jaemin

    2015-01-01

    We report the case of a 64-year-old male with persistent atrial fibrillation (AF) terminated by ethanol infusion into vein of Marshall as add-on therapy. Three-dimensional automated complex fractionated atrial electrogram (CFAE) during AF revealed clustering of CFAE at perimitral isthmus (PMI) and its unipolar mapping showed rotor-like activation, which was suggested to be critical in the perpetuation of AF. AF was organized to atrial tachycardia (AT) by 100% ethanol infusion in the vein of Marshall. Adjunctive radiofrequency ablation at PMI successfully terminated AT and led to bidirectional block of PMI. PMID:26413111

  16. Flutter Analysis of the Shuttle Tile Overlay Repair Concept

    NASA Technical Reports Server (NTRS)

    Bey, Kim S.; Scott, Robert C.; Bartels, Robert E.; Waters, William A.; Chen, Roger

    2007-01-01

    The Space Shuttle tile overlay repair concept, developed at the NASA Johnson Space Center, is designed for on-orbit installation over an area of damaged tile to permit safe re-entry. The thin flexible plate is placed over the damaged area and secured to tile at discreet points around its perimeter. A series of flutter analyses were performed to determine if the onset of flutter met the required safety margins. Normal vibration modes of the panel, obtained from a simplified structural analysis of the installed concept, were combined with a series of aerodynamic analyses of increasing levels of fidelity in terms of modeling the flow physics to determine the onset of flutter. Results from these analyses indicate that it is unlikely that the overlay installed at body point 1800 will flutter during re-entry.

  17. Wing/store flutter with nonlinear pylon stiffness

    NASA Technical Reports Server (NTRS)

    Desmarais, R. N.; Reed, W. H., III

    1980-01-01

    Recent wind tunnel tests and analytical studies show that a store mounted on a pylon with 'soft' pitch stiffness provides substantial increase in flutter speed of fighter aircraft and reduces dependency of flutter on mass and inertia of the store. This concept, termed the decoupler pylon, utilizes a low-frequency control system to maintain pitch alignment of the store during maneuvers and changing flight conditions. Under rapidly changing transient loads, however, the alignment control system may allow the store to momentarily bottom against a relatively stiff backup structure in which case the pylon stiffness acts as a hardening nonlinear spring. Such structural nonlinearities are known to affect not only the flutter speed but also the basic behavior of the instability. This paper examines the influence of pylon stiffness nonlinearities on the flutter characteristics of wing-mounted external stores.

  18. Wing/store flutter with nonlinear pylon stiffness

    NASA Technical Reports Server (NTRS)

    Desmarais, R. N.; Reed, W. H., III

    1980-01-01

    Recent wind tunnel tests and analytical studies show that a store mounted on a pylon with soft pitch stiffness provides substantial increase in flutter speed of fighter aircraft and reduces dependency of flutter on mass and inertia of the store. This concept, termed the decoupler pylon, utilizes a low frequency control system to maintain pitch alignment of the store during maneuvers and changing flight conditions. Under rapidly changing transient loads, however, the alignment control system may allow the store to momentarily bottom against a relatively stiff backup structure in which case the pylon stiffness acts as a hardening nonlinear spring. Such structural nonlinearities are known to affect not only the flutter speed but also the basic behavior of the instability. The influence of pylon stiffness nonlinearities or the flutter characteristics of wing mounted external stores is examined.

  19. Robust Flutter Margin Analysis that Incorporates Flight Data

    NASA Technical Reports Server (NTRS)

    Lind, Rick; Brenner, Martin J.

    1998-01-01

    An approach for computing worst-case flutter margins has been formulated in a robust stability framework. Uncertainty operators are included with a linear model to describe modeling errors and flight variations. The structured singular value, mu, computes a stability margin that directly accounts for these uncertainties. This approach introduces a new method of computing flutter margins and an associated new parameter for describing these margins. The mu margins are robust margins that indicate worst-case stability estimates with respect to the defined uncertainty. Worst-case flutter margins are computed for the F/A-18 Systems Research Aircraft using uncertainty sets generated by flight data analysis. The robust margins demonstrate flight conditions for flutter may lie closer to the flight envelope than previously estimated by p-k analysis.

  20. Shock-boundary layer interaction and transonic flutter

    NASA Astrophysics Data System (ADS)

    Tumkur Karnick, Pradeepa; Venkatraman, Kartik

    2012-11-01

    The transonic flutter dip of an aeroelastic system is primarily caused by compressibility of the flowing fluid. Viscous effects are not dominant in the pre-transonic dip region. In fact, an Euler solver can predict this flutter boundary with considerable accuracy. However with an increase in Mach number the shock moves towards the trailing edge causing shock induced separation. This shock-boundary layer interaction changes the flutter boundary in the transonic and post-transonic dip region significantly. We discuss the effect of viscosity in changing the flutter boundary in the post-transonic dip region using a RANS solver coupled to a two-degree of freedom model of the structural dynamics of a wing.

  1. Modern wing flutter analysis by computational fluid dynamics methods

    NASA Technical Reports Server (NTRS)

    Cunningham, Herbert J.; Batina, John T.; Bennett, Robert M.

    1988-01-01

    The application and assessment of the recently developed CAP-TSD transonic small-disturbance code for flutter prediction is described. The CAP-TSD code has been developed for aeroelastic analysis of complete aircraft configurations and was previously applied to the calculation of steady and unsteady pressures with favorable results. Generalized aerodynamic forces and flutter characteristics are calculated and compared with linear theory results and with experimental data for a 45 deg sweptback wing. These results are in good agreement with the experimental flutter data which is the first step toward validating CAP-TSD for general transonic aeroelastic applications. The paper presents these results and comparisons along with general remarks regarding modern wing flutter analysis by computational fluid dynamics methods.

  2. Effects of endocardial microwave energy ablation

    PubMed Central

    Climent, Vicente; Hurlé, Aquilino; Ho, Siew Yen; Sánchez-Quintana, Damián

    2005-01-01

    Until recently the treatment of atrial fibrillation (AF) consisted primarily of palliation, mostly in the form of pharmacological intervention. However because of recent advances in nonpharmacologic therapies, the current expectation of patients and referring physicians is that AF will be cured, rather than palliated. In recent years there has been a rapid expansion in the availability and variety of energy sources and devices for ablation. One of these energies, microwave, has been applied clinically only in the last few years, and may be a promising technique that is potentially capable of treating a wide range of ventricular and supraventricular arrhythmias. The purpose of this study was to review microwave energy ablation in surgical treatment of AF with special interest in histology and ultrastructure of lesions produced by this endocardial ablation procedure. PMID:16943871

  3. A thermal model for nonlinear panel flutter

    NASA Astrophysics Data System (ADS)

    Gee, David John

    The subject of this research is the nonlinear panel flutter behavior for high Mach number, viscous compressible flow over one side of an isotropic, elastic panel. The fluid/structure interaction is treated as an aerothermoelastic problem in the sense that in addition to aeroelastic coupling, we consider thermal coupling between the fluid and structure. Specifically, at least two distinct heat transfer mechanisms for thermal interaction between the fluid and structure may be important in the panel flutter problem considered here. The primary contribution to thermal stress in the panel is aerodynamic heating. The temperature rise is obtained from a known solution of the compressible Navier-Stokes equations for flow over a flat plate. A secondary source of thermal heating may be due to the panel profile shape and/or any fluttering motion. An unsteady temperature component is obtained by assuming that the unsteady pressure and temperature above the panel are related through an isentropic flow relation. The equation of motion for the panel transverse deflection is based on von Karman large deflection plate theory. The unsteady pressure is computed using aerodynamic piston theory. The PDE is reduced to a system of nonlinear, coupled ordinary differential equations via Galerkin's method and is solved numerically using the 4th-order Runge-Kutta method. However, due to large variation in magnitude of the thermal compressive stress, the stepsize requirement for the numerical integrations is critical and, in fact, limits the usefulness of this procedure. Therefore, bifurcation diagrams are traced out using the pseudo-arclength continuation method (AUTO94). Representative results are given for several combinations of cruise Mach number and altitude. Several stable attractors are found as functions of the in-plane load and dynamic pressure parameters. These two parameters are coupled to the flight conditions and are, therefore, not wholly independent. A direct consequence of

  4. Robust control design techniques for active flutter suppression

    NASA Technical Reports Server (NTRS)

    Ozbay, Hitay; Bachmann, Glen R.

    1994-01-01

    In this paper, an active flutter suppression problem is studied for a thin airfoil in unsteady aerodynamics. The mathematical model of this system is infinite dimensional because of Theodorsen's function which is irrational. Several second order approximations of Theodorsen's function are compared. A finite dimensional model is obtained from such an approximation. We use H infinity control techniques to find a robustly stabilizing controller for active flutter suppression.

  5. Asymptomatic Pulmonary Vein Stenosis: Hemodynamic Adaptation and Successful Ablation

    PubMed Central

    Weinberg, Denis

    2016-01-01

    Pulmonary vein stenosis is a well-established possible complication following an atrial fibrillation ablation of pulmonary veins. Symptoms of pulmonary vein stenosis range from asymptomatic to severe exertional dyspnea. The number of asymptomatic patients with pulmonary vein stenosis is greater than originally estimated; moreover, only about 22% of severe pulmonary vein stenosis requires intervention. We present a patient with severe postatrial fibrillation (AF) ablation pulmonary vein (PV) stenosis, which was seen on multiple imaging modalities including cardiac computed tomography (CT) angiogram, lung perfusion scan, and pulmonary angiogram. This patient did not have any pulmonary symptoms. Hemodynamic changes within a stenosed pulmonary vein might not reflect the clinical severity of the obstruction if redistribution of pulmonary artery flow occurs. Our patient had an abnormal lung perfusion and ventilation (V/Q) scan, suggesting pulmonary artery blood flow redistribution. The patient ultimately underwent safe repeat atrial fibrillation ablation with successful elimination of arrhythmia. PMID:28105376

  6. Atrial fibrillation in obstructive sleep apnea

    PubMed Central

    Goyal, Sandeep K; Sharma, Abhishek

    2013-01-01

    Atrial fibrillation (AF) is a common arrhythmia with rising incidence. Obstructive sleep apnea (OSA) is prevalent among patients with AF. This observation has prompted significant research in understanding the relationship between OSA and AF. Multiple studies support a role of OSA in the initiation and progression of AF. This association has been independent of obesity, body mass index and hypertension. Instability of autonomic tone and wide swings in intrathoracic pressure are seen in OSA. These have been mechanistically linked to initiation of AF in OSA patients by lowering atrial effective refractory period, promoting pulmonary vein discharges and atrial dilation. OSA not only promotes initiation of AF but also makes management of AF difficult. Drug therapy and electrical cardioversion for AF are less successful in presence of OSA. There has been higher rate of early and overall recurrence after catheter ablation of AF in patients with OSA. Treatment of OSA with continuous positive airway pressure has been shown to improve control of AF. However, additional studies are needed to establish a stronger relationship between OSA treatment and success of AF therapies. There should be heightened suspicion of OSA in patients with AF. There is a need for guidelines to screen for OSA as a part of AF management. PMID:23802045

  7. Atrial Fibrillation: The Science behind Its Defiance

    PubMed Central

    Czick, Maureen E.; Shapter, Christine L.; Silverman, David I.

    2016-01-01

    Atrial fibrillation (AF) is the most prevalent arrhythmia in the world, due both to its tenacious treatment resistance, and to the tremendous number of risk factors that set the stage for the atria to fibrillate. Cardiopulmonary, behavioral, and psychological risk factors generate electrical and structural alterations of the atria that promote reentry and wavebreak. These culminate in fibrillation once atrial ectopic beats set the arrhythmia process in motion. There is growing evidence that chronic stress can physically alter the emotion centers of the limbic system, changing their input to the hypothalamic-limbic-autonomic network that regulates autonomic outflow. This leads to imbalance of the parasympathetic and sympathetic nervous systems, most often in favor of sympathetic overactivation. Autonomic imbalance acts as a driving force behind the atrial ectopy and reentry that promote AF. Careful study of AF pathophysiology can illuminate the means that enable AF to elude both pharmacological control and surgical cure, by revealing ways in which antiarrhythmic drugs and surgical and ablation procedures may paradoxically promote fibrillation. Understanding AF pathophysiology can also help clarify the mechanisms by which emerging modalities aiming to correct autonomic imbalance, such as renal sympathetic denervation, may offer potential to better control this arrhythmia. Finally, growing evidence supports lifestyle modification approaches as adjuncts to improve AF control. PMID:27699086

  8. Flutter suppression of plates using passive constrained viscoelastic layers

    NASA Astrophysics Data System (ADS)

    Cunha-Filho, A. G.; de Lima, A. M. G.; Donadon, M. V.; Leão, L. S.

    2016-10-01

    Flutter in aeronautical panels is a self-excited aeroelastic phenomenon which occurs during supersonic flights due to dynamic instability of inertia, elastic and aerodynamic forces of the system. In the flutter condition, when the critical aerodynamic pressure is reached, the vibration amplitudes of the panel become dynamically unstable and increase exponentially with time, significantly affecting the fatigue life of the existing aeronautical components. Thus, in this paper, the interest is to investigate the possibility reducing the effects of the supersonic aeroelastic instability of rectangular plates by applying passive constrained viscoelastic layers. The rationale for such study is the fact that as the addition of viscoelastic materials provides decreased vibration amplitudes it becomes important to quantify the suppression of plate flutter coalescence modes that can be obtained. Moreover, despite the fact that much research on the suppression of panel flutter has been carried out by using passive, semi-active and active control techniques, few works have been proposed to deal with the problem of predicting the flutter boundary of aeroviscoelastic systems, since they must conveniently account for the frequency- and temperature-dependent behavior of the viscoelastic material. After the presentation of the theoretical foundations of the methodology, the description of a numerical study on the flutter analysis of a three-layer sandwich plate is addressed.

  9. Bayesian analysis of the flutter margin method in aeroelasticity

    NASA Astrophysics Data System (ADS)

    Khalil, Mohammad; Poirel, Dominique; Sarkar, Abhijit

    2016-12-01

    A Bayesian statistical framework is presented for Zimmerman and Weissenburger flutter margin method which considers the uncertainties in aeroelastic modal parameters. The proposed methodology overcomes the limitations of the previously developed least-square based estimation technique which relies on the Gaussian approximation of the flutter margin probability density function (pdf). Using the measured free-decay responses at subcritical (preflutter) airspeeds, the joint non-Gaussain posterior pdf of the modal parameters is sampled using the Metropolis-Hastings (MH) Markov chain Monte Carlo (MCMC) algorithm. The posterior MCMC samples of the modal parameters are then used to obtain the flutter margin pdfs and finally the flutter speed pdf. The usefulness of the Bayesian flutter margin method is demonstrated using synthetic data generated from a two-degree-of-freedom pitch-plunge aeroelastic model. The robustness of the statistical framework is demonstrated using different sets of measurement data. It will be shown that the probabilistic (Bayesian) approach reduces the number of test points required in providing a flutter speed estimate for a given accuracy and precision.

  10. Wing flutter boundary prediction using unsteady Euler aerodynamic method

    NASA Technical Reports Server (NTRS)

    Lee-Rausch, Elizabeth M.; Batina, John T.

    1993-01-01

    Modifications to an existing 3D implicit upwind Euler/Navier-Stokes code for the aeroelastic analysis of wings are described. These modifications include the incorporation of a deforming mesh algorithm and the addition of the structural equations of motion for their simultaneous time-integration with the governing flow equations. The paper gives a brief description of these modifications and presents unsteady calculations which check the modifications to the code. Euler flutter results for an isolated 45 deg swept-back wing are compared with experimental data for seven freestream Mach numbers which define the flutter boundary over a range of Mach number from 0.499 to 1.14. These comparisons show good agreement in flutter characteristics for freestream Mach numbers below unity. For freestream Mach numbers above unity, the computed aeroelastic results predict a premature rise in the flutter boundary as compared with the experimental boundary. Steady and unsteady contours of surface Mach number and pressure are included to illustrate the basic flow characteristics of the time-marching flutter calculations and to aid in identifying possible causes for the premature rise in the computational flutter boundary.

  11. Wing flutter boundary prediction using an unsteady Euler aerodynamic method

    NASA Technical Reports Server (NTRS)

    Lee-Rausch, Elizabeth M.; Batina, John T.

    1993-01-01

    Modifications to an existing three-dimensional, implicit, upwind Euler/Navier-Stokes code (CFL3D Version 2.1) for the aeroelastic analysis of wings are described. These modifications, which were previously added to CFL3D Version 1.0, include the incorporation of a deforming mesh algorithm and the addition of the structural equations of motion for their simultaneous time-integration with the government flow equations. The paper gives a brief description of these modifications and presents unsteady calculations which check the modifications to the code. Euler flutter results for an isolated 45 degree swept-back wing are compared with experimental data for seven freestream Mach numbers which define the flutter boundary over a range of Mach number from 0.499 to 1.14. These comparisons show good agreement in flutter characteristics for freestream Mach numbers below unity. For freestream Mach numbers above unity, the computed aeroelastic results predict a premature rise in the flutter boundary as compared with the experimental boundary. Steady and unsteady contours of surface Mach number and pressure are included to illustrate the basic flow characteristics of the time-marching flutter calculations and to aid in identifying possible causes for the premature rise in the computational flutter boundary.

  12. Bayesian analysis of the flutter margin method in aeroelasticity

    SciTech Connect

    Khalil, Mohammad; Poirel, Dominique; Sarkar, Abhijit

    2016-08-27

    A Bayesian statistical framework is presented for Zimmerman and Weissenburger flutter margin method which considers the uncertainties in aeroelastic modal parameters. The proposed methodology overcomes the limitations of the previously developed least-square based estimation technique which relies on the Gaussian approximation of the flutter margin probability density function (pdf). Using the measured free-decay responses at subcritical (preflutter) airspeeds, the joint non-Gaussain posterior pdf of the modal parameters is sampled using the Metropolis–Hastings (MH) Markov chain Monte Carlo (MCMC) algorithm. The posterior MCMC samples of the modal parameters are then used to obtain the flutter margin pdfs and finally the flutter speed pdf. The usefulness of the Bayesian flutter margin method is demonstrated using synthetic data generated from a two-degree-of-freedom pitch-plunge aeroelastic model. The robustness of the statistical framework is demonstrated using different sets of measurement data. In conclusion, it will be shown that the probabilistic (Bayesian) approach reduces the number of test points required in providing a flutter speed estimate for a given accuracy and precision.

  13. Exploratory flutter test in a cryogenic wind tunnel

    NASA Technical Reports Server (NTRS)

    Cole, S. R.

    1985-01-01

    A model consisting of a rigid wing with an integral, flexible beam support that was cantilever mounted from the wall in the NASA LaRC 0.3-m transonic cryogenic tunnel was used in a flutter analysis study. The wing had a rectangular planform of aspect ratio 1.5 and a 64A010 airfoil. Various considerations and procedures for conducting flutter tests in a cryogenic wind tunnel were evaluated. Flutter onset conditions were established from extrapolated subcritical response measurements. A flutter boundary was determined at cryogenic temperatures over a Mach number M range from 0.5 to 0.9. Flutter was obtained at two different Reynolds numbers R at M = 0.5 (R = 4.4 and 18.4 x 10 to the 6th power) and at M = 0.8 (R = 5.0 and 10.4 x 10 to the 6th power). Flutter analyses using subsonic lifting surface (kernel function) aerodynamics were made over the range of test conditions. To evaluate the Reynolds number effects at M = 0.5 and 0.8, the experimental results were adjusted using analytical trends to account for differences in the model test temperatures and mass ratios. The adjusted experimental results indicate that increasing Reynolds number from 5.0 to 20.0 x 10 to the 6th power decreased the dynamic pressure by 4.0 to 6.5 percent at M = 0.5 and 0.8.

  14. Surgery for Atrial Fibrillation.

    PubMed

    Lawrance, Christopher P; Henn, Matthew C; Damiano, Ralph J

    2016-04-01

    Atrial fibrillation is the most common cardiac arrhythmia, and its treatment options include drug therapy or catheter-based or surgical interventions. The surgical treatment of atrial fibrillation has undergone multiple evolutions over the last several decades. The Cox-Maze procedure went on to become the gold standard for the surgical treatment of atrial fibrillation and is currently in its fourth iteration (Cox-Maze IV). This article reviews the indications and preoperative planning for performing a Cox-Maze IV procedure. This article also reviews the literature describing the surgical results for both approaches including comparisons of the Cox-Maze IV to the previous cut-and-sew method.

  15. Surgery for atrial fibrillation.

    PubMed

    Lawrance, Christopher P; Henn, Matthew C; Damiano, Ralph J

    2014-11-01

    Atrial fibrillation is the most common cardiac arrhythmia, and its treatment options include drug therapy or catheter-based or surgical interventions. The surgical treatment of atrial fibrillation has undergone multiple evolutions over the last several decades. The Cox-Maze procedure went on to become the gold standard for the surgical treatment of atrial fibrillation and is currently in its fourth iteration (Cox-Maze IV). This article reviews the indications and preoperative planning for performing a Cox-Maze IV procedure. This article also reviews the literature describing the surgical results for both approaches including comparisons of the Cox-Maze IV to the previous cut-and-sew method.

  16. Maze Procedures for Atrial Fibrillation, From History to Practice

    PubMed Central

    Kik, Charles; Bogers, Ad J.J.C.

    2011-01-01

    Atrial fibrillation may result in significant symptoms, (systemic) thrombo-embolism, as well as tachycardia-induced cardiomyopathy with cardiac failure, and consequently be associated with significant morbidity and mortality. Nowadays symptomatic atrial fibrillation can be treated with catheter-based ablation, surgical ablation or hybrid approaches. In this setting a fairly large number of surgical approaches and procedures are described and being practised. It should be clear that the Cox-maze procedure resulted from building up evidence and experience in different steps, while some of the present surgical approaches and techniques are being based only on technical feasibility with limited experience, rather than on a process of consequent methodology. Some of the issues still under debate are whether or not the maze procedure can be limited to the left atrium or even to isolation of the pulmonary veins or that bi-atrial procedures are indicated, whether or not cardiopulmonary bypass is to be applied and which route of exposure facilitates an optimal result. In addition, maze procedures are not procedures guide by electrophysiological mapping. At least in theory not in all patients all lesions of the maze procedures are necessary. A history and aspects of current practise in surgical treatment of atrial fibrillation is presented.

  17. Atrial Fibrillation Medications

    MedlinePlus

    ... think you are pregnant If you notice red, dark brown or black urine or stools If you ... Fibrillation • Introduction • What is Atrial Fibrillation? • Why AFib Matters • Understand your Risk for AFib Children • Symptoms of ...

  18. Long term results of fast pathway ablation in atrioventricular nodal reentry tachycardia using a modified technique.

    PubMed Central

    Mehta, D.; Gomes, J. A.

    1995-01-01

    OBJECTIVE--To assess immediate and long term success of "fast" pathway catheter ablation with graded use of radiofrequency energy in patients with classic atrioventricular nodal reentrant tachycardia (AVNRT) and evaluate clinical, procedure related, and electrophysiological features affecting long term results. DESIGN--31 consecutive patients with classic AVNRT at electrophysiological study, who were candidates for radiofrequency ablation. Patients were followed for an average of 24 months after ablation. SETTING--All studies and ablations were performed in an electrophysiological laboratory under fluoroscopic guidance using standard electrophysiological techniques. INTERVENTION--Radiofrequency application was performed at the site of proximal His bundle electrogram with A:V ratio of > 1. It was started at 10 W with increment of 5 W to a maximum of 25 W at 60 s. With the onset of junctional rhythm, atrial pacing was begun in order to monitor the PR interval. Application was terminated prematurely with a non-conducted P wave, continued prolongation of the PR interval beyond 50% of the baseline, or a threefold rise in impedance. RESULTS--Successful ablation was possible in 30/31 patients (97%) with an average of seven applications (range 1-10). It was associated with significant prolongation of PR interval (P < 0.001) and AV Wenckebach cycle length (P = 0.01). Ventriculo-atrial conduction was abolished in 24/30 patients (82%) with successful ablation. Two patients developed transient complete heart block (3 and 12 min) and one persistent right branch block. Four patients had late recurrence. Presence of ventriculo-atrial block was the only electrophysiological index predictive of long term success (P = 0.01). CONCLUSIONS--Graded use of radiofrequency energy and atrial pacing to monitor PR interval decreases the risk of atrioventricular block in patients undergoing fast pathway ablation for AVNRT. Ventriculo-atrial block is predictive of long term success and should

  19. Flutter suppression for the Active Flexible Wing - Control system design and experimental validation

    NASA Technical Reports Server (NTRS)

    Waszak, M. R.; Srinathkumar, S.

    1992-01-01

    The synthesis and experimental validation of a control law for an active flutter suppression system for the Active Flexible Wing wind-tunnel model is presented. The design was accomplished with traditional root locus and Nyquist methods using interactive computer graphics tools and with extensive use of simulation-based analysis. The design approach relied on a fundamental understanding of the flutter mechanism to formulate understanding of the flutter mechanism to formulate a simple control law structure. Experimentally, the flutter suppression controller succeeded in simultaneous suppression of two flutter modes, significantly increasing the flutter dynamic pressure despite errors in the design model. The flutter suppression controller was also successfully operated in combination with a rolling maneuver controller to perform flutter suppression during rapid rolling maneuvers.

  20. Cardiovascular Disease Update: Atrial Fibrillation.

    PubMed

    McDivitt, Johnathan D; Barstow, Craig

    2017-03-01

    Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. The prevalence increases with age, especially in the seventh and eighth decades of life. AF also is associated with multiple risk factors and conditions that are managed commonly in family medicine settings, such as hypertension and diabetes. Rhythm control and rate control are primarily equivalent for mortality rate, but patients treated for rhythm control have more hospitalizations; however, rhythm control may be a viable option for select patients. Beta blockers and nondihydropyridine calcium channel blockers can be used to achieve rate control. Pharmacotherapy or electrical cardioversion can be used to achieve rhythm control, and antiarrhythmic drugs are used to maintain sinus rhythm. Catheter ablation is an option for symptomatic patients whose AF is refractory to standard treatment. The CHA2DS2-VASc score should be used to predict the risk of stroke for patients with AF. Patients with nonvalvular AF and a history of stroke or transient ischemic attack or CHA2DS2-VASc scores of 2 or greater should be treated with warfarin or novel oral anticoagulants. Patients with valvular AF should be treated with warfarin.

  1. Flutter clearance of the horizontal tail of the Bellanca Skyrocket II airplane

    NASA Technical Reports Server (NTRS)

    Ricketts, R. H.; Cazier, F. W., Jr.; Farmer, M. G.

    1982-01-01

    The Skyrocket II is an all composite constructed experimental prototype airplane. A flutter clearance program was conducted on the horizontal tail so that the airplane could be safely flown to acquire natural laminar flow aerodynamic data. Ground vibration test data were used in a lifting surface flutter analysis to predict symmetric and antisymmetric flutter boundaries. Subcritical response data which were acquired during flight tests are compared with the analytical results. The final flutter clearance placard speed was based on flight test data.

  2. Atrial fibrillation (acute onset)

    PubMed Central

    2014-01-01

    Introduction Acute atrial fibrillation is rapid, irregular, and chaotic atrial activity of recent onset. Various definitions of acute atrial fibrillation have been used in the literature, but for the purposes of this review we have included studies where atrial fibrillation may have occurred up to 7 days previously. Risk factors for acute atrial fibrillation include increasing age, cardiovascular disease, alcohol, diabetes, and lung disease. Acute atrial fibrillation increases the risk of stroke and heart failure. The condition resolves spontaneously within 24 to 48 hours in more than 50% of people; however, many people will require interventions to control heart rate or restore sinus rhythm. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent embolism, for conversion to sinus rhythm, and to control heart rate in people with recent-onset atrial fibrillation (within 7 days) who are haemodynamically stable? We searched: Medline, Embase, The Cochrane Library, and other important databases up to April 2014 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 26 studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: amiodarone, antithrombotic treatment before cardioversion, atenolol, bisoprolol, carvedilol, digoxin, diltiazem, direct current cardioversion, flecainide, metoprolol, nebivolol, propafenone, sotalol, timolol, and verapamil. PMID:25430048

  3. Atrial Septal Defect (For Kids)

    MedlinePlus

    ... Dictionary of Medical Words En Español What Other Kids Are Reading Taking Care of Your Ears Taking ... an X-ray Atrial Septal Defect KidsHealth > For Kids > Atrial Septal Defect Print A A A What's ...

  4. Can Atrial Fibrillation Be Prevented?

    MedlinePlus

    ... from the NHLBI on Twitter. How Can Atrial Fibrillation Be Prevented? Following a healthy lifestyle and taking ... for heart disease may help you prevent atrial fibrillation (AF). These steps include: Following a heart healthy ...

  5. Stroke Prevention in Atrial Fibrillation

    MedlinePlus

    ... Association Cardiology Patient Page Stroke Prevention in Atrial Fibrillation Christian T. Ruff Download PDF https://doi.org/ ... an irregular and fast heartbeat. What Causes Atrial Fibrillation? Several factors and medical conditions make it more ...

  6. Loss of atrial contractility is primary cause of atrial dilatation during first days of atrial fibrillation.

    PubMed

    Schotten, Ulrich; de Haan, Sunniva; Neuberger, Hans-Ruprecht; Eijsbouts, Sabine; Blaauw, Yuri; Tieleman, Robert; Allessie, Maurits

    2004-11-01

    Atrial fibrillation (AF) induces a progressive dilatation of the atria which in turn might promote the arrhythmia. The mechanism of atrial dilatation during AF is not known. To test the hypothesis that loss of atrial contractile function is a primary cause of atrial dilatation during the first days of AF, eight goats were chronically instrumented with epicardial electrodes, a pressure transducer in the right atrium, and piezoelectric crystals to measure right atrial diameter. AF was induced with the use of repetitive burst pacing. Atrial contractility was assessed during sinus rhythm, atrial pacing (160-, 300-, and 400-ms cycle length), and electrically induced AF. The compliance of the fibrillating right atrium was measured during unloading the atria with diuretics and loading with 1 liter of saline. All measurements were repeated after 6, 12, and 24 h of AF and then once a day during the first 5 days of AF. Recovery of the observed changes after spontaneous cardioversion was also studied. After 5 days of AF, atrial contractility during sinus rhythm or slow atrial pacing was greatly reduced. During rapid pacing (160 ms) or AF, the amplitude of the atrial pressure waves had declined to 20% of control. The compliance of the fibrillating atria increased twofold, whereas the right atrial pressure was unchanged. As a result, the mean right atrial diameter increased by approximately 12%. All changes were reversible within 3 days of sinus rhythm. We conclude that atrial dilatation during the first days of AF is due to an increase in atrial compliance caused by loss of atrial contractility during AF. Atrial compliance and size are restored when atrial contractility recovers after cardioversion of AF.

  7. Analytical and experimental investigation of flutter suppression by piezoelectric actuation

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer

    1993-01-01

    The objective of this research was to analytically and experimentally study the capabilities of piezoelectric plate actuators for suppressing flutter. Piezoelectric materials are characterized by their ability to produce voltage when subjected to a mechanical strain. The converse piezoelectric effect can be utilized to actuate a structure by applying a voltage. For this investigation, a two-degree-of-freedom wind tunnel model was designed, analyzed, and tested. The model consisted of a rigid wing and a flexible mount system that permitted a translational and a rotational degree of freedom. The model was designed such that flutter was encountered within the testing envelope of the wind tunnel. Actuators made of piezoelectric material were affixed to leaf springs of the mount system. Command signals, applied to the piezoelectric actuators, exerted control over the damping and stiffness properties. A mathematical aeroservoelastic model was constructed by using finite element methods, laminated plate theory, and aeroelastic analysis tools. Plant characteristics were determined from this model and verified by open loop experimental tests. A flutter suppression control law was designed and implemented on a digital control computer. Closed loop flutter testing was conducted. The experimental results represent the first time that adaptive materials have been used to actively suppress flutter. They demonstrate that small, carefully placed actuating plates can be used effectively to control aeroelastic response.

  8. Aeroelastic flutter in axial flow-The continuum theory

    NASA Astrophysics Data System (ADS)

    Balakrishnan, A. V.; Tuffaha, A. M.

    2012-11-01

    We present a mathematical continuum model for aeroelastic flutter of a Goland type structure subject to axial airflow. The model consists of a linearized Euler full potential equation for the airflow and a second order linear structure equation in two degrees of freedom plunge and pitch (bending and torsion). These are coupled through velocity matching type conditions and Kutta type condition describing the pressure jump. The approach mimics the approach used to study aeroelastic flutter in the normal flow case [?], which deals with aircraft applications. We layout the theoretical framework for determining the aeroelastic modes and the flutter point of the structure at any given mode. We will focus on the torsion aeroelastic modes and consider bending modes in future work. The importance of studying aeroelastic flutter in the axial flow case has come to attention in the recent years in light of non aircraft applications of which we mention two: the problem of snoring or apnea, which can be characterized as palattal flutter and secondly power generation from structures placed in axial flow.

  9. Bayesian analysis of the flutter margin method in aeroelasticity

    DOE PAGES

    Khalil, Mohammad; Poirel, Dominique; Sarkar, Abhijit

    2016-08-27

    A Bayesian statistical framework is presented for Zimmerman and Weissenburger flutter margin method which considers the uncertainties in aeroelastic modal parameters. The proposed methodology overcomes the limitations of the previously developed least-square based estimation technique which relies on the Gaussian approximation of the flutter margin probability density function (pdf). Using the measured free-decay responses at subcritical (preflutter) airspeeds, the joint non-Gaussain posterior pdf of the modal parameters is sampled using the Metropolis–Hastings (MH) Markov chain Monte Carlo (MCMC) algorithm. The posterior MCMC samples of the modal parameters are then used to obtain the flutter margin pdfs and finally the fluttermore » speed pdf. The usefulness of the Bayesian flutter margin method is demonstrated using synthetic data generated from a two-degree-of-freedom pitch-plunge aeroelastic model. The robustness of the statistical framework is demonstrated using different sets of measurement data. In conclusion, it will be shown that the probabilistic (Bayesian) approach reduces the number of test points required in providing a flutter speed estimate for a given accuracy and precision.« less

  10. Predicting Flutter and Forced Response in Turbomachinery

    NASA Technical Reports Server (NTRS)

    VanZante, Dale E.; Adamczyk, John J.; Srivastava, Rakesh; Bakhle, Milind A.; Shabbir, Aamir; Chen, Jen-Ping; Janus, J. Mark; To, Wai-Ming; Barter, John

    2005-01-01

    TURBO-AE is a computer code that enables detailed, high-fidelity modeling of aeroelastic and unsteady aerodynamic characteristics for prediction of flutter, forced response, and blade-row interaction effects in turbomachinery. Flow regimes that can be modeled include subsonic, transonic, and supersonic, with attached and/or separated flow fields. The three-dimensional Reynolds-averaged Navier-Stokes equations are solved numerically to obtain extremely accurate descriptions of unsteady flow fields in multistage turbomachinery configurations. Blade vibration is simulated by use of a dynamic-grid-deformation technique to calculate the energy exchange for determining the aerodynamic damping of vibrations of blades. The aerodynamic damping can be used to assess the stability of a blade row. TURBO-AE also calculates the unsteady blade loading attributable to such external sources of excitation as incoming gusts and blade-row interactions. These blade loadings, along with aerodynamic damping, are used to calculate the forced responses of blades to predict their fatigue lives. Phase-lagged boundary conditions based on the direct-store method are used to calculate nonzero interblade phase-angle oscillations; this practice eliminates the need to model multiple blade passages, and, hence, enables large savings in computational resources.

  11. Treatment strategy for treating atrial-esophageal fistula: esophageal stenting or surgical repair?

    PubMed Central

    Zhou, Bing; Cen, Xue-Jiang; Qian, Lin-Yan; Pang, Jie; Zou, Hai; Ding, Ya-Hui

    2016-01-01

    Abstract Introduction: Atrial-esophageal fistula (AEF) is a rare severe disease, which may be associated with radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) or intraoperative radiofrequency ablation of atrial fibrillation (IRAAF). Clinical Findings: We reported a case of a 67-year-old man with AEF following RFCA of AF, who treated with esophageal stenting and surgical repair. Outcomes: He was attacked by out-of-control sepsis and infectious shock after surgery and died. Literature review: We analyzed 57 relevant articles about AEF from 2003 to 2015 by searching PubMed database. According literatures, the most common symptoms were fever, rigor, sepsis, and neurologic symptoms. Chest computer tomography (CT) and contrast enhanced CT may be the reliable noninvasive diagnosis methods because of high sensitive for AEF. Conclusion: Make a definition diagnosis in time with early primary surgical repair may save their lives. Conservative treatment or esophageal stenting alone may not be a better choice for AEF patients. PMID:27787367

  12. Overview of Recent Flight Flutter Testing Research at NASA Dryden

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J.; Lind, Richard C.; Voracek, David F.

    1997-01-01

    In response to the concerns of the aeroelastic community, NASA Dryden Flight Research Center, Edwards, California, is conducting research into improving the flight flutter (including aeroservoelasticity) test process with more accurate and automated techniques for stability boundary prediction. The important elements of this effort so far include the following: (1) excitation mechanisms for enhanced vibration data to reduce uncertainty levels in stability estimates; (2) investigation of a variety of frequency, time, and wavelet analysis techniques for signal processing, stability estimation, and nonlinear identification; and (3) robust flutter boundary prediction to substantially reduce the test matrix for flutter clearance. These are critical research topics addressing the concerns of a recent AGARD Specialists' Meeting on Advanced Aeroservoelastic Testing and Data Analysis. This paper addresses these items using flight test data from the F/A-18 Systems Research Aircraft and the F/A-18 High Alpha Research Vehicle.

  13. Nonlinear flutter analysis of stiffened composite panels in supersonic flow

    NASA Astrophysics Data System (ADS)

    Yuan, Kaihua; Qiu, Zhiping

    2010-02-01

    The flutter instability of stiffened composite panels subjected to aerodynamic forces in the supersonic flow is investigated. Based on Hamilton’s principle, the aeroelastic model of the composite panel is established by using the von Karman large deflection plate theory, piston theory aerodynamics and the quasi-steady thermal stress theory. Then, using the finite element method along with Bogner-Fox-Schmit elements and three-dimensional beam elements, the nonlinear equations of motion are derived. The effect of stiffening scheme on the flutter critical dynamic pressure is demonstrated through the numerical example, and the nonlinear flutter characteristics of stiffened composite panels are also analyzed in the time domain. This will lay the foundation for design of panel structures employed in aerospace vehicles.

  14. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    NASA Technical Reports Server (NTRS)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  15. Resonance Effects in the NASA Transonic Flutter Cascade Facility

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; Capece, V. R.; Ford, C. T.

    2003-01-01

    Investigations of unsteady pressure loadings on the blades of fans operating near the stall flutter boundary are carried out under simulated conditions in the NASA Transonic Flutter Cascade facility (TFC). It has been observed that for inlet Mach numbers of about 0.8, the cascade flowfield exhibits intense low-frequency pressure oscillations. The origins of these oscillations were not clear. It was speculated that this behavior was either caused by instabilities in the blade separated flow zone or that it was a tunnel resonance phenomenon. It has now been determined that the strong low-frequency oscillations, observed in the TFC facility, are not a cascade phenomenon contributing to blade flutter, but that they are solely caused by the tunnel resonance characteristics. Most likely, the self-induced oscillations originate in the system of exit duct resonators. For sure, the self-induced oscillations can be significantly suppressed for a narrow range of inlet Mach numbers by tuning one of the resonators. A considerable amount of flutter simulation data has been acquired in this facility to date, and therefore it is of interest to know how much this tunnel self-induced flow oscillation influences the experimental data at high subsonic Mach numbers since this facility is being used to simulate flutter in transonic fans. In short, can this body of experimental data still be used reliably to verify computer codes for blade flutter and blade life predictions? To answer this question a study on resonance effects in the NASA TFC facility was carried out. The results, based on spectral and ensemble averaging analysis of the cascade data, showed that the interaction between self-induced oscillations and forced blade motion oscillations is very weak and can generally be neglected. The forced motion data acquired with the mistuned tunnel, when strong self-induced oscillations were present, can be used as reliable forced pressure fluctuations provided that they are extracted

  16. Fan Flutter Computations Using the Harmonic Balance Method

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Thomas, Jeffrey P.; Reddy, T.S.R.

    2009-01-01

    An experimental forward-swept fan encountered flutter at part-speed conditions during wind tunnel testing. A new propulsion aeroelasticity code, based on a computational fluid dynamics (CFD) approach, was used to model the aeroelastic behavior of this fan. This threedimensional code models the unsteady flowfield due to blade vibrations using a harmonic balance method to solve the Navier-Stokes equations. This paper describes the flutter calculations and compares the results to experimental measurements and previous results from a time-accurate propulsion aeroelasticity code.

  17. Vector plotting as an indication of the approach to flutter

    NASA Technical Reports Server (NTRS)

    Broadbent, E. G.

    1975-01-01

    A binary flexure-torsion analysis was made to check theoretically a method for predicting flutter which depends on plotting vectorially the amplitudes of response relative to the exciting force and extracting the relevant damping rate. The results of this calculation are given in graphs both of the vector plots themselves and of the estimated damping rate against forward speed. The estimated damping rates are compared with calculated values. The method has the advantage that in a flight flutter test damping can be estimated from continuous excitation records: the method is an extension of the Kennedy and Pancu technique used in ground resonance testing.

  18. Flight testing air-to-air missiles for flutter

    NASA Technical Reports Server (NTRS)

    Kutschinski, C. R.

    1975-01-01

    The philosophy of the design of air-to-air missiles and hence of flight testing them for flutter differs from that of manned aircraft. Primary emphasis is put on analytical and laboratory evaluation of missile susceptibility to aeroelastic and aero-servo-elastic instabilities and uses flight testing for confirmation of the absence of such instabilities. Flight testing for flutter is accomplished by using specially instrumented programmed missiles, air or ground launched with a booster to reach the extreme flight conditions of tactical use, or by using guided missiles with telemetered performance data. The instrumentation and testing techniques are discussed along with the success of recent flight tests.

  19. Ambient wind energy harvesting using cross-flow fluttering

    NASA Astrophysics Data System (ADS)

    Li, Shuguang; Yuan, Jianping; Lipson, Hod

    2011-01-01

    In this experimental study, we propose and test a bioinspired piezo-leaf architecture which converts wind energy into electrical energy by wind-induced fluttering motion. While conventional fluttering devices are arranged in parallel with the flow direction, here we explore a dangling cross-flow stalk arrangement. This architecture amplifies the vibration by an order of magnitude, making it appropriate for low-cost organic piezomaterials. We fabricated prototypes using flexible piezoelectric materials as stalks and polymer film as leaves. A series of experiments demonstrated a peak output power of approximately 600 μ W and maximum power density of approximately 2 mW/cm3 from a single leaf.

  20. Control surface spanwise placement in active flutter suppression systems

    NASA Technical Reports Server (NTRS)

    Nissim, E.; Burken, John J.

    1988-01-01

    A method is developed that determines the placement of an active control surface for maximum effectiveness in suppressing flutter. No specific control law is required by this method which is based on the aerodynamic energy concept. It is argued that the spanwise placement of the active controls should coincide with the locations where maximum energy per unit span is fed into the system. The method enables one to determine the distribution, over the different surfaces of the aircraft, of the energy input into the system as a result of the unstable fluttering mode. The method is illustrated using three numerical examples.

  1. Perturbation and harmonic balance methods for nonlinear panel flutter.

    NASA Technical Reports Server (NTRS)

    Kuo, C.-C.; Morino, L.; Dugundji, J.

    1972-01-01

    A systematic way of applying both perturbation methods and harmonic balance methods to nonlinear panel flutter problems is developed here. Results obtained by both these methods for two-dimensional simply supported and three-dimensional clamped-clamped plates with six modes agree well with those obtained by the straightforward direct integration method, yet require less computer time and provide better insight into the solutions. Effects of viscoelastic structural damping on the flutter stability boundary are generally found to be destabilizing and the postflutter behavior becomes more explosive. The methods developed here may be of interest in related vibration problems.

  2. Comparisons of Flutter Analyses for an Experimental Fan

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Reddy, T. S. R.; Stefko, George L.

    2010-01-01

    Two propulsion aeroelasticity codes were used to model the aeroelastic characteristics of an experimental forward-swept fan that encountered flutter during wind tunnel testing. Both of these three-dimensional codes model the unsteady flowfield due to blade vibrations using the Navier-Stokes equations. In the first approach, the unsteady flow equations are solved using an implicit time-marching approach. In the second approach, the unsteady flow equations are converted to a harmonic balance form and solved using a pseudo-time marching method. This paper describes the flutter calculations and compares the results to experimental measurements.

  3. Application of NASTRAN to large deflection supersonic flutter of panels

    NASA Technical Reports Server (NTRS)

    Mei, C.; Rogers, J. L., Jr.

    1976-01-01

    Flat panel flutter at high supersonic Mach number is analyzed using NASTRAN Level 16.0 by means of modifications to the code. Two-dimensional plate theory and quasi-steady aerodynamic theory are employed. The finite element formulation and solution procedure are presented. Modifications to the NASTRAN code are discussed. Convergence characteristics of the iteration processes are also briefly discussed. Effects of aerodynamic damping, boundary support condition and applied in-plane loading are included. Comparison of nonlinear vibration and linear flutter results with analytical solutions demonstrate that excellent accuracy is obtained with NASTRAN.

  4. Comparison of supercritical and conventional wing flutter characteristics

    NASA Technical Reports Server (NTRS)

    Farmer, M. G.; Hanson, P. W.; Wynne, E. C.

    1976-01-01

    A wind-tunnel study was undertaken to directly compare the measured flutter boundaries of two dynamically similar aeroelastic models which had the same planform, maximum thickness-to-chord ratio, and as nearly identical stiffness and mass distributions as possible, with one wing having a supercritical airfoil and the other a conventional airfoil. The considerations and problems associated with flutter testing supercritical wing models at or near design lift coefficients are discussed, and the measured transonic boundaries of the two wings are compared with boundaries calculated with a subsonic lifting surface theory.

  5. Large Scale Flutter Data for Design of Rotating Blades Using Navier-Stokes Equations

    NASA Technical Reports Server (NTRS)

    Guruswamy, Guru P.

    2012-01-01

    A procedure to compute flutter boundaries of rotating blades is presented; a) Navier-Stokes equations. b) Frequency domain method compatible with industry practice. Procedure is initially validated: a) Unsteady loads with flapping wing experiment. b) Flutter boundary with fixed wing experiment. Large scale flutter computation is demonstrated for rotating blade: a) Single job submission script. b) Flutter boundary in 24 hour wall clock time with 100 cores. c) Linearly scalable with number of cores. Tested with 1000 cores that produced data in 25 hrs for 10 flutter boundaries. Further wall-clock speed-up is possible by performing parallel computations within each case.

  6. Flutter analysis and testing of pairs of aerodynamically interfering delta wings

    NASA Technical Reports Server (NTRS)

    Chipman, R. R.; Rauch, F. J.

    1973-01-01

    To examine the effect on flutter of the aerodynamic interference between pairs of closely spaced delta wings, several structurally uncoupled 1/80th-scale models were studied by experiment and analysis. Flutter test boundaries run in a 26-in transonic blowdown wind tunnel were compared with subsonic analytical results generated using the doublet lattice method. Trends for several combinations of vertical and longitudinal wing separation showed that flutter speeds can be significantly lowered in closely spaced configurations. For some configurations, a new flutter mechanism, characterized by coupling of the flexible modes from both surfaces at a distinctive flutter frequency, was predicted and observed.

  7. Winglet effects on the flutter of twin-engine-transport type wing

    NASA Technical Reports Server (NTRS)

    Bhatia, K. G.; Nagaraja, K. S.; Ruhlin, C. L.

    1984-01-01

    Flutter characteristics of a cantilevered high aspect ratio wing with winglet were investigated. The configuration represented a current technology, twin-engine airplane. A low-speed and a high-speed model were used to evaluate compressibility effects through transonic Mach numbers and a wide range of mass-density ratios. Four flutter mechanisms were obtained in test, as well as analysis from various combinations of configuration parameters. The coupling between wing tip vertical and chordwise motions was shown to have significant effect under some conditions. It is concluded that, for the flutter model configurations studied, the winglet related flutter was amenable to the conventional flutter analysis techniques.

  8. Pellet ablation and ablation model development

    SciTech Connect

    Houlberg, W.A.

    1989-01-01

    A broad survey of pellet ablation is given, based primarily on information presented at this meeting. The implications of various experimental observations for ablation theory are derived from qualitative arguments of the physics involved. The major elements of a more complete ablation theory are then outlined in terms of these observations. This is followed by a few suggestions on improving the connections between theory and experimental results through examination of ablation data. Although this is a rather aggressive undertaking for such a brief (and undoubtedly incomplete) assessment, some of the discussion may help us advance the understanding of pellet ablation. 17 refs.

  9. Tailored management of atrial fibrillation using a LGE-MRI based model: from the clinic to the electrophysiology laboratory.

    PubMed

    Vergara, Gaston R; Marrouche, Nassir F

    2011-04-01

    Ablation provides a good therapeutic alternative for atrial fibrillation (AF) management; however, its effectiveness relies in adequate patient selection. Late gadolinium enhancement-magnetic resonance imaging (LGE-MRI) allows for atrial arrhythmic substrate, as well as postablation scarring visualization. In this article, we describe a new staging system for AF based on the amount of left atrial enhancement on LGE-MRI (Utah I ≤ 5%, Utah II >5-20%, Utah III > 20-35%, and Utah IV > 35%). On the basis of patient stage, a more tailored approach to AF management can be taken. This includes triaging appropriate candidates for ablation (Utah stages I-III), as well as anticoagulation management based on an increase on the predictive statistics of the CHADS(2). LGE-MRI also allows for ablation lesion characterization. Acute edema, defined as enhancement on T2-weighted MRI images immediately post-AF ablation correlates with low voltage areas but not with LGE-MRI-defined scar. Post-AF ablation LGE-MRI scans show significant heterogeneity in the atrial wall on portions subject to radiofrequency (RF). We have postulated that some of these areas correspond to no-reflow type phenomenon. Postablation LGE-MRI can also help identify breaks in lesion sets and its correlation with conduction recovery has been used successfully to guide redo procedures. Real-time MRI-based ablation system has the potential advantage of tissue lesion visualization during RF delivery. To that end, we have developed a 3-Tesla-based real-time MRI ablation system. We demonstrated the feasibility to safely navigate, pace, and record intracardiac EGMs in the atrial chambers, as well as applying RF energy while directly visualizing lesion formation in real time. 

  10. Stall Flutter Control of a Smart Blade Section Undergoing Asymmetric Limit Oscillations

    DOE PAGES

    Li, Nailu; Balas, Mark J.; Nikoueeyan, Pourya; ...

    2016-01-01

    Stall flutter is an aeroelastic phenomenon resulting in unwanted oscillatory loads on the blade, such as wind turbine blade, helicopter rotor blade, and other flexible wing blades. Although the stall flutter and related aeroelastic control have been studied theoretically and experimentally, microtab control of asymmetric limit cycle oscillations (LCOs) in stall flutter cases has not been generally investigated. This paper presents an aeroservoelastic model to study the microtab control of the blade section undergoing moderate stall flutter and deep stall flutter separately. The effects of different dynamic stall conditions and the consequent asymmetric LCOs for both stall cases are simulatedmore » and analyzed. Then, for the design of the stall flutter controller, the potential sensor signal for the stall flutter, the microtab control capability of the stall flutter, and the control algorithm for the stall flutter are studied. The improvement and the superiority of the proposed adaptive stall flutter controller are shown by comparison with a simple stall flutter controller.« less

  11. Study of flutter related computational procedures for minimum weight structural sizing of advanced aircraft, supplemental data

    NASA Technical Reports Server (NTRS)

    Oconnell, R. F.; Hassig, H. J.; Radovcich, N. A.

    1975-01-01

    Computational aspects of (1) flutter optimization (minimization of structural mass subject to specified flutter requirements), (2) methods for solving the flutter equation, and (3) efficient methods for computing generalized aerodynamic force coefficients in the repetitive analysis environment of computer-aided structural design are discussed. Specific areas included: a two-dimensional Regula Falsi approach to solving the generalized flutter equation; method of incremented flutter analysis and its applications; the use of velocity potential influence coefficients in a five-matrix product formulation of the generalized aerodynamic force coefficients; options for computational operations required to generate generalized aerodynamic force coefficients; theoretical considerations related to optimization with one or more flutter constraints; and expressions for derivatives of flutter-related quantities with respect to design variables.

  12. Exploiting periodicity to extract the atrial activity in atrial arrhythmias

    NASA Astrophysics Data System (ADS)

    Llinares, Raul; Igual, Jorge

    2011-12-01

    Atrial fibrillation disorders are one of the main arrhythmias of the elderly. The atrial and ventricular activities are decoupled during an atrial fibrillation episode, and very rapid and irregular waves replace the usual atrial P-wave in a normal sinus rhythm electrocardiogram (ECG). The estimation of these wavelets is a must for clinical analysis. We propose a new approach to this problem focused on the quasiperiodicity of these wavelets. Atrial activity is characterized by a main atrial rhythm in the interval 3-12 Hz. It enables us to establish the problem as the separation of the original sources from the instantaneous linear combination of them recorded in the ECG or the extraction of only the atrial component exploiting the quasiperiodic feature of the atrial signal. This methodology implies the previous estimation of such main atrial period. We present two algorithms that separate and extract the atrial rhythm starting from a prior estimation of the main atrial frequency. The first one is an algebraic method based on the maximization of a cost function that measures the periodicity. The other one is an adaptive algorithm that exploits the decorrelation of the atrial and other signals diagonalizing the correlation matrices at multiple lags of the period of atrial activity. The algorithms are applied successfully to synthetic and real data. In simulated ECGs, the average correlation index obtained was 0.811 and 0.847, respectively. In real ECGs, the accuracy of the results was validated using spectral and temporal parameters. The average peak frequency and spectral concentration obtained were 5.550 and 5.554 Hz and 56.3 and 54.4%, respectively, and the kurtosis was 0.266 and 0.695. For validation purposes, we compared the proposed algorithms with established methods, obtaining better results for simulated and real registers.

  13. Body surface localization of left and right atrial high-frequency rotors in atrial fibrillation patients: A clinical-computational study

    PubMed Central

    Rodrigo, Miguel; Guillem, María S.; Climent, Andreu M.; Pedrón-Torrecilla, Jorge; Liberos, Alejandro; Millet, José; Fernández-Avilés, Francisco; Atienza, Felipe; Berenfeld, Omer

    2014-01-01

    BACKGROUND Ablation is an effective therapy in patients with atrial fibrillation (AF) in which an electrical driver can be identified. OBJECTIVE The aim of this study was to present and discuss a novel and strictly noninvasive approach to map and identify atrial regions responsible for AF perpetuation. METHODS Surface potential recordings of 14 patients with AF were recorded using a 67-lead recording system. Singularity points (SPs) were identified in surface phase maps after band-pass filtering at the highest dominant frequency (HDF). Mathematical models of combined atria and torso were constructed and used to investigate the ability of surface phase maps to estimate rotor activity in the atrial wall. RESULTS The simulations show that surface SPs originate at atrial SPs, but not all atrial SPs are reflected at the surface. Stable SPs were found in AF signals during 8.3% ± 5.7% vs 73.1% ± 16.8% of the time in unfiltered vs HDF-filtered patient data, respectively (P < .01). The average duration of each rotational pattern was also lower in unfiltered than in HDF-filtered AF signals (160 ± 43 ms vs 342 ± 138 ms; P < .01), resulting in 2.8 ± 0.7 rotations per rotor. Band-pass filtering reduced the apparent meandering of surface HDF rotors by reducing the effect of the atrial electrical activity occurring at different frequencies. Torso surface SPs representing HDF rotors during AF were reflected at specific areas corresponding to the fastest atrial location. CONCLUSION Phase analysis of surface potential signals after HDF filtering during AF shows reentrant drivers localized to either the left atrium or the right atrium, helping in localizing ablation targets. PMID:24846374

  14. Clinical AV nodal reentrant tachycardia in a patient with left sided accessory pathway and immediate occurrence of antidromic AV reentrant tachycardia after slow pathway ablation.

    PubMed

    Surber, Ralf; Kühnert, Helmut; Heinke, Matthias; Malur, Frank-Michael; Sigusch, Holger H; Figulla, Hans R

    2002-06-01

    The only inducible arrhythmia in a patient with exclusive antegrade conducting left anterolateral accessory pathway, consists of slow/fast atrioventricular nodal reentrant tachycardia. After radiofrequency catheter ablation of the slow pathway, true antidromic AV reentrant tachycardia was easily induced by atrial pacing. Following ablation of the accessory pathway no arrhythmia could be induced.

  15. Aeroservoelastic Modeling of Body Freedom Flutter for Control System Design

    NASA Technical Reports Server (NTRS)

    Ouellette, Jeffrey

    2017-01-01

    The communication of this method is being used by NASA in the ongoing collaborations with groups interested in the X-56A flight test program. Model generation for body freedom flutter Addressing issues in: State Consistency, Low frequency dynamics, Unsteady aerodynamics. Applied approach to X-56A MUTT: Comparing to flight test data.

  16. Flutter of buckled shape memory alloy reinforced laminates

    NASA Astrophysics Data System (ADS)

    Kuo, Shih-Yao; Shiau, Le-Chung; Lai, Chin-Hsin

    2012-03-01

    The effect of shape memory alloys (SMA) on the linear and nonlinear flutter behaviors of buckled cross-ply and angle-ply laminates was investigated in the frequency and time domains using the finite element method. In particular, this study takes the first move toward examining the effect of varying the SMA fiber spacing. Von Karman large deformation assumptions and quasi-steady aerodynamic theory were employed. The flutter boundary, stability boundary, time history response, and phase plane plots of SMA reinforced cross-ply and angle-ply laminates are presented. The numerical results show that increase in the SMA fiber volume fraction and prestrain may generate more recovery stress, and increase the stiffness of the SMA reinforced laminates. Therefore, the flutter boundary and critical load of the plate may be increased significantly. All five types of panel behavior, namely flat, buckled, limit-cycle, periodic, and chaotic motion, are clearly displayed and successively identified. This study sheds light on improving the flutter boundary efficiently by increasing the SMA fiber volume fraction to reinforce the center of the plate.

  17. Selective reinforcement of wing structure for flutter prevention.

    NASA Technical Reports Server (NTRS)

    Cooper, P. A.; Stroud, W. J.

    1972-01-01

    The results of an analytical study are presented on the use of boron polyimide filamentary composite material for the purpose of increasing the flutter speed of a simple titanium full depth sandwich wing structure designed for strength. The results clearly demonstrate that selective reinforcement of wing surfaces, using judiciously placed filamentary composites, promises sizable mass savings in the design of advanced aircraft structures.

  18. Aeroservoelastic Modeling of Body Freedom Flutter for Control System Design

    NASA Technical Reports Server (NTRS)

    Ouellette, Jeffrey

    2017-01-01

    One of the most severe forms of coupling between aeroelasticity and flight dynamics is an instability called freedom flutter. The existing tools often assume relatively weak coupling, and are therefore unable to accurately model body freedom flutter. Because the existing tools were developed from traditional flutter analysis models, inconsistencies in the final models are not compatible with control system design tools. To resolve these issues, a number of small, but significant changes have been made to the existing approaches. A frequency domain transformation is used with the unsteady aerodynamics to ensure a more physically consistent stability axis rational function approximation of the unsteady aerodynamic model. The aerodynamic model is augmented with additional terms to account for limitations of the baseline unsteady aerodynamic model and to account for the gravity forces. An assumed modes method is used for the structural model to ensure a consistent definition of the aircraft states across the flight envelope. The X-56A stiff wing flight-test data were used to validate the current modeling approach. The flight-test data does not show body-freedom flutter, but does show coupling between the flight dynamics and the aeroelastic dynamics and the effects of the fuel weight.

  19. Eulerian-Lagrangian Simulations of Transonic Flutter Instabilities

    NASA Technical Reports Server (NTRS)

    Bendiksen, Oddvar O.

    1994-01-01

    This paper presents an overview of recent applications of Eulerian-Lagrangian computational schemes in simulating transonic flutter instabilities. This approach, the fluid-structure system is treated as a single continuum dynamics problem, by switching from an Eulerian to a Lagrangian formulation at the fluid-structure boundary. This computational approach effectively eliminates the phase integration errors associated with previous methods, where the fluid and structure are integrated sequentially using different schemes. The formulation is based on Hamilton's Principle in mixed coordinates, and both finite volume and finite element discretization schemes are considered. Results from numerical simulations of transonic flutter instabilities are presented for isolated wings, thin panels, and turbomachinery blades. The results suggest that the method is capable of reproducing the energy exchange between the fluid and the structure with significantly less error than existing methods. Localized flutter modes and panel flutter modes involving traveling waves can also be simulated effectively with no a priori knowledge of the type of instability involved.

  20. Flutter-driven triboelectrification for harvesting wind energy.

    PubMed

    Bae, Jihyun; Lee, Jeongsu; Kim, SeongMin; Ha, Jaewook; Lee, Byoung-Sun; Park, YoungJun; Choong, Chweelin; Kim, Jin-Baek; Wang, Zhong Lin; Kim, Ho-Young; Park, Jong-Jin; Chung, U-In

    2014-09-23

    Technologies to harvest electrical energy from wind have vast potentials because wind is one of the cleanest and most sustainable energy sources that nature provides. Here we propose a flutter-driven triboelectric generator that uses contact electrification caused by the self-sustained oscillation of flags. We study the coupled interaction between a fluttering flexible flag and a rigid plate. In doing so, we find three distinct contact modes: single, double and chaotic. The flutter-driven triboelectric generator having small dimensions of 7.5 × 5 cm at wind speed of 15 ms(-1) exhibits high-electrical performances: an instantaneous output voltage of 200 V and a current of 60 μA with a high frequency of 158 Hz, giving an average power density of approximately 0.86 mW. The flutter-driven triboelectric generation is a promising technology to drive electric devices in the outdoor environments in a sustainable manner.

  1. Flight test of passive wing/store flutter suppression

    NASA Technical Reports Server (NTRS)

    Cazier, F. W., Jr.; Kehoe, M. W.

    1986-01-01

    Flight tests were performed on an F-16 airplane carrying on each wing an AIM-9J wingtip missile, a GBU-8 bomb near midspan, and an external fuel tank. Baseline flights with the GBU-8 mounted on a standard pylon established that this configuration is characterized by an antisymmetric limited amplitude flutter oscillation within the operational envelope. The airplane was then flown with GBU-8 mounted on the decoupler pylon. The decoupler pylon is a NASA concept of passive wing-store flutter suppression achieved by providing a low store-pylon pitch frequency. The decoupler pylon successfully suppressed wing-store flutter throughout the flight envelope. A 37 percent increase in flutter velocity over the standard pylon was demonstrated. Maneuvers with load factors to 4g were performed. Although the static store displacements during maneuvers were not sufficiently large to be of concern, a store pitch alignment system was tested and performed successfully. One GBU-8 was ejected demonstrating that weapon separation from the decoupler pylon is normal.

  2. Flutter analysis of highly swept delta wings by conventional methods

    NASA Technical Reports Server (NTRS)

    Gibbons, M. D.; Soistmann, D. L.; Bennett, R. M.

    1988-01-01

    The flutter boundaries of six thin highly-swept delta-platform wings have been calculated. Comparisons are made between experimental data and results using several aerodynamic methods. The aerodynamic methods used include a subsonic and supersonic kernel function, second order piston theory, and a transonic small disturbance code. The dynamic equations of motion are solved using analytically calculated mode shapes and frequencies.

  3. Posterior left atrial wall hematoma mimicking cystic intracavitary atrial mass.

    PubMed

    Bahnacy, Yasser; Suresh, Cheriyil; Dawoud, Hamed; Zubaid, Mohammad

    2010-10-01

    Atrial myxoma is the most common benign primary tumor of the heart most commonly in the left atrium (LA). Cystic or cavitated intracardiac masses are rare. We report the case of a 43-year-old male patient admitted with chest infection, hemoptysis, and severe respiratory distress, who had to be ventilated. Chest computed tomography showed bilateral lung consolidation with large mass occupying the region of the LA. Transthoracic echocardiography and transesophageal echocardiography showed a large intracavitary left atrial cystic mobile mass. Open-heart surgical exploration did not show any mass inside the LA. A posterior left atrial wall hematoma was found and evacuated. Biopsies confirmed the presence of blood clots. Posterior left atrial wall hematoma may appear as left atrial intracavitary cystic mass and should be included in the differential diagnosis of cystic left atrial mass.

  4. Genetics Home Reference: familial atrial fibrillation

    MedlinePlus

    ... Home Health Conditions familial atrial fibrillation familial atrial fibrillation Enable Javascript to view the expand/collapse boxes. ... PDF Open All Close All Description Familial atrial fibrillation is an inherited condition that disrupts the heart's ...

  5. About the Effect of Control on Flutter and Post-Flutter of a Supersonic/Hypersonic Cross-Sectional Wing

    NASA Technical Reports Server (NTRS)

    Silva, Walter A.; Librescu, Liviu; Marzocca, Piergiovanni

    2001-01-01

    The control of the flutter instability and the conversion of the dangerous character of the flutter instability boundary into the undangerous one of a cross-sectional wing in a supersonic/hypersonic flow field is presented. The objective of this paper is twofold: i) to analyze the implications of nonlinear unsteady aerodynamics and physical nonlinearities on the character of the instability boundary in the presence of a control capability, and ii) to outline the effects played in the same respect by some important parameters of the aeroelastic system. As a by-product of this analysis, the implications of the active control on the linearized flutter behavior of the system are captured and emphasized. The bifurcation behavior of the open/closed loop aeroelastic system in the vicinity of the flutter boundary is studied via the use of a new methodology based on the Liapunov First Quantity. The expected outcome of this study is: a) to greatly enhance the scope and reliability of the aeroelastic analysis and design criteria of advanced supersonic/hypersonic flight vehicles and, b) provide a theoretical basis for the analysis of more complex nonlinear aeroelastic systems.

  6. About the Effect of Control on Flutter and Post-Flutter of a Supersonic/Hypersonic Cross-Sectional Wing

    NASA Technical Reports Server (NTRS)

    Marzocca, Piergiovanni; Librescu, Liviu; Silva, Walter A.

    2000-01-01

    The control of the flutter instability and the conversion of the dangerous character of the flutter instability boundary into the undangerous one of a cross-sectional wing in a supersonic/hypersonic flow field is presented. The objective of this paper is twofold: i) to analyze the implications of nonlinear unsteady aerodynamics and physical nonlinearities on the character of the instability boundary in the presence of a control capability, and ii) to outline the effects played in the same respect by some important parameters of the aeroelastic system. As a by-product of this analysis, the implications of the active control on the linearized flutter behavior of the system are captured and emphasized. The bifurcation behavior of the open/closed loop aeroelastic system in the vicinity of the flutter boundary is studied via the use of a new methodology based on the Liapunov First Quantity. The expected outcome of this study is: a) to greatly enhance the scope and reliability of the aeroelastic analysis and design criteria of advanced supersonic/hypersonic flight vehicles and, b) provide a theoretical basis for the analysis of more complex nonlinear aeroelastic systems.

  7. Study of flutter related computational procedures for minimum weight structural sizing of advanced aircraft

    NASA Technical Reports Server (NTRS)

    Oconnell, R. F.; Hassig, H. J.; Radovcich, N. A.

    1976-01-01

    Results of a study of the development of flutter modules applicable to automated structural design of advanced aircraft configurations, such as a supersonic transport, are presented. Automated structural design is restricted to automated sizing of the elements of a given structural model. It includes a flutter optimization procedure; i.e., a procedure for arriving at a structure with minimum mass for satisfying flutter constraints. Methods of solving the flutter equation and computing the generalized aerodynamic force coefficients in the repetitive analysis environment of a flutter optimization procedure are studied, and recommended approaches are presented. Five approaches to flutter optimization are explained in detail and compared. An approach to flutter optimization incorporating some of the methods discussed is presented. Problems related to flutter optimization in a realistic design environment are discussed and an integrated approach to the entire flutter task is presented. Recommendations for further investigations are made. Results of numerical evaluations, applying the five methods of flutter optimization to the same design task, are presented.

  8. A new atrial septostomy technique.

    PubMed

    Park, S C; Zuberbuhler, J R; Neches, W H; Lenox, C C; Zoltun, R A

    1975-01-01

    Balloon atrial septostomy is usually ineffective if the atrial septum is thickened. A technique for incising the atrial septum is described. A no. 6 French catheter was modified to enclose a tiny surgical blade. The distal end of the blade was pivoted to the catheter tip, and the proximal end was attached to a guide wire in the catheter lumen. Advancing the guide wire protruded the blade through a slit in the long axis of the tip of the catheter. Atrial septostomy was performed in five newborn lambs in vivo and in adult dog hearts and human hearts in vitro by advancing the catheter tip across the atrial septum with the blade retracted and withdrawing it to the right atrium with the blade extended. Eight to 12 mm lacerations of the atrial septum were produced and could be extended by subsequent balloon septostomy. The technique may be useful when balloon septostomy has been ineffective.

  9. Slow Conduction in the Border Zones of Patchy Fibrosis Stabilizes the Drivers for Atrial Fibrillation: Insights from Multi-Scale Human Atrial Modeling

    PubMed Central

    Morgan, Ross; Colman, Michael A.; Chubb, Henry; Seemann, Gunnar; Aslanidi, Oleg V.

    2016-01-01

    Introduction: The genesis of atrial fibrillation (AF) and success of AF ablation therapy have been strongly linked with atrial fibrosis. Increasing evidence suggests that patient-specific distributions of fibrosis may determine the locations of electrical drivers (rotors) sustaining AF, but the underlying mechanisms are incompletely understood. This study aims to elucidate a missing mechanistic link between patient-specific fibrosis distributions and AF drivers. Methods: 3D atrial models integrated human atrial geometry, rule-based fiber orientation, region-specific electrophysiology, and AF-induced ionic remodeling. A novel detailed model for an atrial fibroblast was developed, and effects of myocyte-fibroblast (M-F) coupling were explored at single-cell, 1D tissue and 3D atria levels. Left atrial LGE MRI datasets from 3 chronic AF patients were segmented to provide the patient-specific distributions of fibrosis. The data was non-linearly registered and mapped to the 3D atria model. Six distinctive fibrosis levels (0–healthy tissue, 5–dense fibrosis) were identified based on LGE MRI intensity and modeled as progressively increasing M-F coupling and decreasing atrial tissue coupling. Uniform 3D atrial model with diffuse (level 2) fibrosis was considered for comparison. Results: In single cells and tissue, the largest effect of atrial M-F coupling was on the myocyte resting membrane potential, leading to partial inactivation of sodium current and reduction of conduction velocity (CV). In the 3D atria, further to the M-F coupling, effects of fibrosis on tissue coupling greatly reduce atrial CV. AF was initiated by fast pacing in each 3D model with either uniform or patient-specific fibrosis. High variation in fibrosis distributions between the models resulted in varying complexity of AF, with several drivers emerging. In the diffuse fibrosis models, waves randomly meandered through the atria, whereas in each the patient-specific models, rotors stabilized in

  10. Development and Flight Test of an Active Flutter Suppression System for the F-4F with Stores. Part I. Design of the Active Flutter Suppression System.

    DTIC Science & Technology

    1982-09-01

    extensive research programs accompanied by wind tunnel tests in the field of active flutter and elastic mode suppression. In 1975, MBB conducted a successful...Pro- gram," Paper presented at the 51th SMP of AGARD, Athens 13-18 April 1980. 6. 0. Sensburg, J. Becker, H. Honlinger, "Active Control of Flutter and

  11. Radiofrequency Ablation of Liver Tumors

    MedlinePlus

    ... Site Index A-Z Radiofrequency Ablation (RFA) of Liver Tumors Radiofrequency ablation (RFA) is a treatment that ... of Liver Tumors? What is Radiofrequency Ablation of Liver Tumors? Radiofrequency ablation, sometimes referred to as RFA, ...

  12. The atrial natriuretic factor.

    PubMed Central

    Genest, J

    1986-01-01

    In less than three years since the rapid and potent natriuretic response to intravenous injection of atrial myocardial extract in rats was reported the factor responsible for the diuretic, natriuretic, and vasodilating activity of the atrial homogenates was isolated, its chemical structure elucidated, and its total synthesis achieved. Also the cDNA and the gene encoding for the atrial natriuretic factor in mice, rats, and man have been cloned and the chromosomal site identified. The major effects of this hormone are vasodilatation, prevention and inhibition of the contraction induced by noradrenaline and angiotensin II, diuresis, and natriuresis associated in most instances with a pronounced increase in glomerular filtration rate and filtration fraction, inhibition of aldosterone secretion, and considerable stimulation of particulate guanylate cyclase activity. High density specific binding sites have been demonstrated in the zona glomerulosa of the adrenal cortex, in the renal glomeruli, and in the collecting ducts, and in the brain areas involved in the regulation of blood pressure and of sodium and water (AV3V region, subfornical organ, nucleus tractus solitarius, area postrema). Images Fig 1 Fig 5 PMID:2945572

  13. Development of rapid preexcited ventricular response to atrial fibrillation in a patient with intermittent preexcitation.

    PubMed

    Gemma, Lee W; Steinberg, Leonard A; Prystowsky, Eric N; Padanilam, Benzy J

    2013-03-01

    Intermittent preexcitation during sinus rhythm is indicative of an accessory pathway at a very low risk for sudden death. We present the case of a 49-year-old man with intermittent preexcitation who subsequently developed rapid atrial fibrillation with a shortest preexcited R-R interval of 230 milliseconds. Electrophysiology study showed intermittent preexcitation at baseline and 1:1 anterograde accessory pathway conduction to 220 milliseconds in the presence of 1 mcg/min isoproterenol infusion. The pathway was successfully ablated at the lateral mitral annulus. Accessory pathways highly sensitive to catecholamines may show intermittent preexcitation at baseline with potential for rapid conduction during atrial fibrillation and sudden death.

  14. Managing atrial fibrillation in the very elderly patient: challenges and solutions

    PubMed Central

    Karamichalakis, Nikolaos; Letsas, Konstantinos P; Vlachos, Konstantinos; Georgopoulos, Stamatis; Bakalakos, Athanasios; Efremidis, Michael; Sideris, Antonios

    2015-01-01

    Atrial fibrillation (AF) is the most common arrhythmia affecting elderly patients. Management and treatment of AF in this rapidly growing population of older patients involve a comprehensive assessment that includes comorbidities, functional, and social status. The cornerstone in therapy of AF is thromboembolic protection. Anticoagulation therapy has evolved, using conventional or newer medications. Percutaneous left atrial appendage closure is a new invasive procedure evolving as an alternative to systematic anticoagulation therapy. Rate or rhythm control leads to relief in symptoms, fewer hospitalizations, and an improvement in quality of life. Invasive methods, such as catheter ablation, are the new frontier of treatment in maintaining an even sinus rhythm in this particular population. PMID:26604772

  15. Ablative skin resurfacing.

    PubMed

    Chwalek, Jennifer; Goldberg, David J

    2011-01-01

    Ablative skin resurfacing has remained the gold standard for treating photodamage and acne scars since the development of the first CO(2) lasers. CO(2) and Er:YAG lasers emit infrared light, which targets water resulting in tissue contraction and collagen formation. The first ablative laser systems created significant thermal damage resulting in unacceptably high rates of scarring and prolonged healing. Newer devices, such as high-energy pulsed lasers and fractional ablative lasers, are capable of achieving significant improvements with fewer side effects and shorter recovery times. While ablative resurfacing has become safer, careful patient selection is still important to avoid post-treatment scarring, dyspigmentation, and infections. Clinicians utilizing ablative devices need to be aware of possible side effects in order to maximize results and patient satisfaction. This chapter reviews the background of ablative lasers including the types of ablative lasers, mechanism of action, indications for ablative resurfacing, and possible side effects.

  16. A computational transonic flutter boundary tracking procedure. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Gallman, J. W.; Batina, J. T.; Yang, T. Y.

    1986-01-01

    An automated flutter boundary tracking procedure for the efficient calculation of transonic flutter boundaries is presented. The procedure uses aeroelastic responses to march along the boundary by taking steps in speed and Mach number, thereby reducing the number of response calculations previously required to determine a transonic flutter boundary. Flutter boundary results are presented for a typical airfoil section oscillating with pitch and plunge degrees of freedom. These transonic flutter boundaries are in good agreement with exact boundaries calculated using the conventional time-marching method. The tracking procedure is extended to include static aeroelastic twist as a simulation of the static deformation of a wing and contains all of the essential features that are required to apply it to practical three-dimensional cases. The procedure is also applied to flutter boundaries as a function of structural parameters.

  17. Coupled-Mode Flutter of Bending-Bending Type in Highly-Flexible Uniform Airfoils

    NASA Astrophysics Data System (ADS)

    Pourazarm, Pariya; Modarres-Sadeghi, Yahya

    2016-11-01

    We study the behavior of a highly flexible uniform airfoil placed in wind both numerically and experimentally. It is shown that for a non-rotating highly-flexible cantilevered airfoil, placed at very small angles of attack (less than 1 degree), the airfoil loses its stability by buckling. For slightly higher angles of attack (more than 1 degree) a coupled-mode flutter in which the first and the second flapwise modes coalesce toward a flutter mode is observed, and thus the observed flutter has a bending-bending nature. The flutter onset and frequency found experimentally matched the numerical predictions. If the same airfoil is forced to rotate about its fixed end, the static deflection decreases and the observed couple-mode flutter becomes of flapwise-torsional type, same as what has already been observed for flutter of rotating wind turbine blades. The support provided by the National Science Foundation, CBET-1437988, is greatly acknowledged.

  18. Supersonic Panel Flutter Test Results for Flat Fiber-Glass Sandwich Panels with Foamed Cores

    NASA Technical Reports Server (NTRS)

    Tuovila, W. J.; Presnell, John G., Jr.

    1961-01-01

    Flutter tests have been made on flat panels having a 1/4 inch-thick plastic-foam core covered with thin fiber-glass laminates. The testing was done in the Langley Unitary Plan wind tunnel at Mach numbers from 1.76 t o 2.87. The flutter boundary for these panels was found to be near the flutter boundary of thin metal panels when compared on the basis of an equivalent panel stiffness. The results also demonstrated that the depth of the cavity behind the panel has a pronounced influence on flutter. Changing the cavity depth from 1 1/2 inches to 1/2 inch reduced the dynamic pressure at start of flutter by 40 percent. No flutter was obtained when the spacers on the back of the panel were against the bottom of the cavity.

  19. A Genetic Algorithm Optimization Method for Mapping Non-Conducting Atrial Regions: A Theoretical Feasibility Study.

    PubMed

    Shiff, Shai; Swissa, Moshe; Zlochiver, Sharon

    2016-03-01

    Atrial ablation has been recently utilized for curing atrial fibrillation. The success rate of empirical ablation is relatively low as often the exact locations of the arrhythmogenic sources remain elusive. Guided ablation has been proposed to improve ablation technique by providing guidance regarding the potential localization of the sources; yet to date no main technological solution has been widely adopted as an integral part of the ablation process. Here we propose a genetic algorithm optimization technique to map a major arrhythmogenic substance-non-conducting regions (NCRs). Excitation delays in a set of electrodes of known locations are measured following external tissue stimulation, and the spatial distribution of obstacles that is most likely to yield the measured delays is reconstructed. A forward problem module was solved to provide synthetic time delay measurements using a 2D human atrial model with known NCR distribution. An inverse genetic algorithm module was implemented to optimally reconstruct the locations of the now unknown obstacle distribution using the synthetic measurements. The performance of the algorithm was demonstrated for several distributions varying in NCR number and shape. The proposed algorithm was found robust to measurements with a signal-to-noise ratio of at least -20 dB, and for measuring electrodes separated by up to 3.2 mm. Our results support the feasibility of the proposed algorithm in mapping NCRs; nevertheless, further research is required prior to clinical implementation for incorporating more complex atrial tissue geometrical configurations as well as for testing the algorithm with experimental data.

  20. Surgical perspectives in the management of atrial fibrillation

    PubMed Central

    Kyprianou, Katerina; Pericleous, Agamemnon; Stavrou, Antonio; Dimitrakaki, Inetzi A; Challoumas, Dimitrios; Dimitrakakis, Georgios

    2016-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia and a huge public health burden associated with significant morbidity and mortality. For decades an increasing number of patients have undergone surgical treatment of AF, mainly during concomitant cardiac surgery. This has sparked a drive for conducting further studies and researching this field. With the cornerstone Cox-Maze III “cut and sew” procedure being technically challenging, the focus in current literature has turned towards less invasive techniques. The introduction of ablative devices has revolutionised the surgical management of AF, moving away from the traditional surgical lesions. The hybrid procedure, a combination of catheter and surgical ablation is another promising new technique aiming to improve outcomes. Despite the increasing number of studies looking at various aspects of the surgical management of AF, the literature would benefit from more uniformly conducted randomised control trials. PMID:26839656

  1. Survey of aircraft subcritical flight flutter testing methods

    NASA Technical Reports Server (NTRS)

    Rosenbaum, R.

    1974-01-01

    The results of a survey of U. S., British and French subcritical aircraft flight flutter testing methods are presented and evaluation of the applicability of these methods to the testing of the space shuttle are discussed. Ten U. S. aircraft programs covering the large civil transport aircraft and a variety of military aircraft are reviewed. In addition, three major French and British programs are covered by the survey. The significant differences between the U. S., French and British practices in the areas of methods of excitation, data acquisition, transmission and analysis are reviewed. The effect of integrating the digital computer into the flight flutter test program is discussed. Significant saving in analysis and flight test time are shown to result from the use of special digital computer routines and digital filters.

  2. Flutter, Postflutter, and Control of a Supersonic Wing Section

    NASA Technical Reports Server (NTRS)

    Marzocca, Piergiovanni; Librescu, Liviu; Silva, Walter A.

    2002-01-01

    A number of issues related to the flutter and postflutter of two-dimensional supersonic lifting surfaces are addressed. Among them there are the 1) investigation of the implications of the nonlinear unsteady aerodynamics and structural nonlinearities on the stable/unstable character of the limit cycle and 2) study of the implications of the incorporation of a control capability on both the flutter boundary and the postflutter behavior. To this end, a powerful methodology based on the Lyapunov first quantity is implemented. Such a treatment of the problem enables one to get a better understanding of the various factors involved in the nonlinear aeroelastic problem, including the stable and unstable limit cycle. In addition, it constitutes a first step toward a more general investigation of nonlinear aeroelastic phenomena of three-dimensional lifting surfaces.

  3. Active flutter suppression using optical output feedback digital controllers

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A method for synthesizing digital active flutter suppression controllers using the concept of optimal output feedback is presented. A convergent algorithm is employed to determine constrained control law parameters that minimize an infinite time discrete quadratic performance index. Low order compensator dynamics are included in the control law and the compensator parameters are computed along with the output feedback gain as part of the optimization process. An input noise adjustment procedure is used to improve the stability margins of the digital active flutter controller. Sample rate variation, prefilter pole variation, control structure variation and gain scheduling are discussed. A digital control law which accommodates computation delay can stabilize the wing with reasonable rms performance and adequate stability margins.

  4. On curve veering and flutter of rotating blades

    NASA Technical Reports Server (NTRS)

    Afolabi, Dare; Mehmed, Oral

    1993-01-01

    The eigenvalues of rotating blades usually change with rotation speed according to the Stodola-Southwell criterion. Under certain circumstances, the loci of eigenvalues belonging to two distinct modes of vibration approach each other very closely, and it may appear as if the loci cross each other. However, our study indicates that the observable frequency loci of an undamped rotating blade do not cross, but must either repel each other (leading to 'curve veering'), or attract each other (leading to 'frequency coalescence'). Our results are reached by using standard arguments from algebraic geometry--the theory of algebraic curves and catastrophe theory. We conclude that it is important to resolve an apparent crossing of eigenvalue loci into either a frequency coalescence or a curve veering, because frequency coalescence is dangerous since it leads to flutter, whereas curve veering does not precipitate flutter and is, therefore, harmless with respect to elastic stability.

  5. Investigating the Transonic Flutter Boundary of the Benchmark Supercritical Wing

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer; Chwalowski, Pawel

    2017-01-01

    This paper builds on the computational aeroelastic results published previously and generated in support of the second Aeroelastic Prediction Workshop for the NASA Benchmark Supercritical Wing configuration. The computational results are obtained using FUN3D, an unstructured grid Reynolds-Averaged Navier-Stokes solver developed at the NASA Langley Research Center. The analysis results focus on understanding the dip in the transonic flutter boundary at a single Mach number (0.74), exploring an angle of attack range of ??1 to 8 and dynamic pressures from wind off to beyond flutter onset. The rigid analysis results are examined for insights into the behavior of the aeroelastic system. Both static and dynamic aeroelastic simulation results are also examined.

  6. Comparative study between two different active flutter suppression systems

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1978-01-01

    An activated leading-edge (LE)-tailing-edge (TE) control system is applied to a drone aircraft with the objective of enabling the drone to fly subsonically at dynamic pressures which are 44% above the open-loop flutter dynamic pressure. The control synthesis approach is based on the aerodynamic energy concept and it incorporates recent developments in this area. A comparison is made between the performance of the activated LE-TE control system and the performance of a TE control system, analyzed in a previous work. The results obtained indicate that although all the control systems achieve the flutter suppression objectives, the TE control system appears to be somewhat superior to the LE-TE control system, in this specific application. This superiority is manifested through reduced values of control surface activity over a wide range of flight conditions.

  7. Application of a flight test and data analysis technique to flutter of a drone aircraft

    NASA Technical Reports Server (NTRS)

    Bennett, R. M.

    1981-01-01

    Modal identification results presented were obtained from recent flight flutter tests of a drone vehicle with a research wing (DAST ARW-1 for Drones for Aerodynamic and Structural Testing, Aeroelastic Research Wing-1). This vehicle is equipped with an active flutter suppression system (FSS). Frequency and damping of several modes are determined by a time domain modal analysis of the impulse response function obtained by Fourier transformations of data from fast swept sine wave excitation by the FSS control surface on the wing. Flutter points are determined for two different altitudes with the FSS off. Data are given for near the flutter boundary with the FSS on.

  8. Application of a flight test and data analysis technique to flutter of a drone aircraft

    NASA Technical Reports Server (NTRS)

    Bennett, R. M.; Abel, I.

    1981-01-01

    Modal identification results are presented that were obtained from recent flight flutter tests of a drone vehicle with a research wing equipped with an active flutter suppression system (FSS). Frequency and damping of several modes are determined by a time domain modal analysis of the impulse response function obtained by Fourier transformations of data from fast swept sine wave excitation by the FSS control surfaces on the wing. Flutter points are determined for two different altitudes with the FSS off. Data are given for near the flutter boundary with the FSS on.

  9. A wind-tunnel investigation of a B-52 model flutter suppression system

    NASA Technical Reports Server (NTRS)

    Redd, L. T.; Gilman, J., Jr.; Cooley, D. E.; Sevart, F. D.

    1974-01-01

    Flutter modeling techniques have been successfully extended to the difficult case of the active suppression of flutter. The demonstration was conducted in a transonic dynamics tunnel using a 1/30 scale, elastic, dynamic model of a Boeing B-52 control configured vehicle. The results from the study show that with the flutter suppression system operating there is a substantial increase in the damping associated with the critical flutter mode. The results also show good correlation between the damping characteristics of the model and the aircraft.

  10. Flutter suppression digital control law design and testing for the AFW wind-tunnel model

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek

    1992-01-01

    Design of a control law for simultaneously suppressing the symmetric and antisymmetric flutter modes of a string mounted fixed-in-roll aeroelastic wind tunnel model is described. The flutter suppression control law was designed using linear quadratic Gaussian theory and involved control law order reduction, a gain root-locus study, and the use of previous experimental results. A 23 percent increase in open-loop flutter dynamic pressure was demonstrated during the wind tunnel test. Rapid roll maneuvers at 11 percent above the symmetric flutter boundary were also performed when the model was in a free-to-roll configuration.

  11. Hummingbird feather sounds are produced by aeroelastic flutter, not vortex-induced vibration.

    PubMed

    Clark, Christopher J; Elias, Damian O; Prum, Richard O

    2013-09-15

    Males in the 'bee' hummingbird clade produce distinctive, species-specific sounds with fluttering tail feathers during courtship displays. Flutter may be the result of vortex shedding or aeroelastic interactions. We investigated the underlying mechanics of flutter and sound production of a series of different feathers in a wind tunnel. All feathers tested were capable of fluttering at frequencies varying from 0.3 to 10 kHz. At low airspeeds (Uair) feather flutter was highly damped, but at a threshold airspeed (U*) the feathers abruptly entered a limit-cycle vibration and produced sound. Loudness increased with airspeed in most but not all feathers. Reduced frequency of flutter varied by an order of magnitude, and declined with increasing Uair in all feathers. This, along with the presence of strong harmonics, multiple modes of flutter and several other non-linear effects indicates that flutter is not simply a vortex-induced vibration, and that the accompanying sounds are not vortex whistles. Flutter is instead aeroelastic, in which structural (inertial/elastic) properties of the feather interact variably with aerodynamic forces, producing diverse acoustic results.

  12. Development, simulation validation, and wind tunnel testing of a digital controller system for flutter suppression

    NASA Technical Reports Server (NTRS)

    Hoadley, Sherwood Tiffany; Buttrill, Carey S.; Mcgraw, Sandra M.; Houck, Jacob A.

    1991-01-01

    Flutter suppression (FS) is one of the active control concepts being investigated by the AFW program. The design goal for FS control laws was to increase the passive flutter dynamic pressure by 30 percent. In order to meet this goal, the FS control laws had to be capable of suppressing both symmetric and antisymmetric flutter instabilities simultaneously. In addition, the FS control laws had to be practical and low-order, robust and capable of real time execution within the 200 hz. sampling time. The purpose here is to present an overview of the development, simulation validation, and wind tunnel testing of a digital controller system for flutter suppression.

  13. Flutter suppression digital control law design and testing for the AFW wind tunnel model

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek

    1994-01-01

    The design of a control law for simultaneously suppressing the symmetric and antisymmetric flutter modes of a sting mounted fixed-in-roll aeroelastic wind-tunnel model is described. The flutter suppression control law was designed using linear quadratic Gaussian theory, and it also involved control law order reduction, a gain root-locus study, and use of previous experimental results. A 23 percent increase in the open-loop flutter dynamic pressure was demonstrated during the wind-tunnel test. Rapid roll maneuvers at 11 percent above the symmetric flutter boundary were also performed when the model was in a free-to-roll configuration.

  14. a Time-Domain Method for Transonic Flutter Analysis with Multidirectional Coupled Vibrations

    NASA Astrophysics Data System (ADS)

    Guo, Tongqing; Lu, Zhiliang; Wu, Yongjian

    Gridgen is employed for static multi-block grid generation. A rapid deforming technique is employed for dynamic grids. Flutters are numerically analyzed in the time domain with a coupled solution of unsteady Euler equations and structural equations of motion. Based on variable stiffness method of transonic flutter analysis, a time-domain method of transonic flutter analysis with multi-directional coupled vibrations is develpoed. For completeness, flutter characteristics of a wing model with winglets and an aircraft model with external stores are numerically analyzed.

  15. Report on a Cooperative Programme on Active Flutter Suppression,

    DTIC Science & Technology

    1980-08-01

    assistance to member nations for the purpose of increasing their scientific and technical potential ; - Recommending effective ways for the member nations to ...experience gained in the above-mentioned wind tunnel tests pointed the way to further improve- ments that could be made in the flutter suppression system...console at Northrop’s Hawthorne facility prior to test entry. The wind tunnel tests were performed in September-October 1979 at the NASA Langley Center

  16. Aerothermoelastic Topology Optimization with Flutter and Buckling Metrics (Postprint)

    DTIC Science & Technology

    2013-07-01

    magnitude of the thermal load. Furthermore, the off-design performance of the topologies will be examined. 2 Problem description The geometry of a metallic...elastic Fig. 1 Panel geometry and design domain surface embedded in an otherwise rigid plane (the outer sur- face of a high-speed aircraft wing, or the...unsteady finite element solutions are used to ascer- tain the thermal buckling and flutter boundaries of the panel topologies. The geometry seen in Fig. 1

  17. Flutter prediction for a wing with active aileron control

    NASA Technical Reports Server (NTRS)

    Penning, K.; Sandlin, D. R.

    1983-01-01

    A method for predicting the vibrational stability of an aircraft with an analog active aileron flutter suppression system (FSS) is expained. Active aileron refers to the use of an active control system connected to the aileron to damp vibrations. Wing vibrations are sensed by accelerometers and the information is used to deflect the aileron. Aerodynamic force caused by the aileron deflection oppose wing vibrations and effectively add additional damping to the system.

  18. The influence of trailed vorticity on flutter speed estimations

    NASA Astrophysics Data System (ADS)

    Pirrung, Georg R.; Madsen, Helge Aa; Kim, Taeseong

    2014-06-01

    This paper briefly describes the implementation of a coupled near and far wake model for wind turbine rotor induction in the aeroelastic code HAWC2 and its application for flutter analysis of the NREL 5 MW wind turbine. The model consists of a far wake part based on Blade Element Momentum (BEM) theory, which is coupled with Beddoes' near wake model for trailed vorticity. The first part of this work outlines the implementation in HAWC2, with a focus on the interaction of the induction from the blade based near wake model with the induction from the polar grid based BEM model in HAWC2. The influence of the near wake model on the aeroelastic stability of the blades of the NREL 5 MW turbine in overspeed conditions is investigated in the second part of the paper. The analysis is based on a runaway case in which the turbine is free to speed up without generator torque and vibrations start building up at a critical rotor speed. Blades with modified torsional and flapwise stiffness are also investigated. A flutter analysis is often part of the stability investigations for new blades but is normally carried out with engineering models that do not include the influence of unsteady trailed vorticity. Including this influence results in a slightly increased safety margin against classical flutter in all simulated cases.

  19. Whirl Flutter Studies for a SSTOL Transport Demonstrator

    NASA Technical Reports Server (NTRS)

    Acree, C. W., Jr.; Hoffman, Krishna

    2004-01-01

    A proposed new class of aircraft - the Advanced Theater Transport (ATT) will combine strategic range and high payload with 'Super-STOL' (short take-off and landing) capability. It is also proposed to modify a YC-15 into a technology demonstrator with a 20-deg tilt wing; four, eight-bladed propellers; cross-shafted gearboxes and V-22 engines. These constitute a unique combination of design features that potentially affect performance, loads and whirl-mode stability (whirl flutter). NASA Ames Research Center is working with Boeing and Hamilton Sundstrand on technology challenges presented by the concept; the purpose of NASA involvement is to establish requirements for the demonstrator and for early design guidance, with emphasis on whirl flutter. CAMRAD II is being used to study the effects of various design features on whirl flutter, with special attention to areas where such features differ from existing aircraft, notably tiltrotors. Although the stability margins appear to be more than adequate, the concept requires significantly different analytical methods, principally including far more blade modes, than typically used for tiltrotors.

  20. Design, test, and evaluation of three active flutter suppression controllers

    NASA Technical Reports Server (NTRS)

    Adams, William M., Jr.; Christhilf, David M.; Waszak, Martin R.; Mukhopadhyay, Vivek; Srinathkumar, S.

    1992-01-01

    Three control law design techniques for flutter suppression are presented. Each technique uses multiple control surfaces and/or sensors. The first method uses traditional tools (such as pole/zero loci and Nyquist diagrams) for producing a controller that has minimal complexity and which is sufficiently robust to handle plant uncertainty. The second procedure uses linear combinations of several accelerometer signals and dynamic compensation to synthesize the model rate of the critical mode for feedback to the distributed control surfaces. The third technique starts with a minimum-energy linear quadratic Gaussian controller, iteratively modifies intensity matrices corresponding to input and output noise, and applies controller order reduction to achieve a low-order, robust controller. The resulting designs were implemented digitally and tested subsonically on the active flexible wing wind-tunnel model in the Langley Transonic Dynamics Tunnel. Only the traditional pole/zero loci design was sufficiently robust to errors in the nominal plant to successfully suppress flutter during the test. The traditional pole/zero loci design provided simultaneous suppression of symmetric and antisymmetric flutter with a 24-percent increase in attainable dynamic pressure. Posttest analyses are shown which illustrate the problems encountered with the other laws.

  1. Application of Approximate Unsteady Aerodynamics for Flutter Analysis

    NASA Technical Reports Server (NTRS)

    Pak, Chan-gi; Li, Wesley W.

    2010-01-01

    A technique for approximating the modal aerodynamic influence coefficient (AIC) matrices by using basis functions has been developed. A process for using the resulting approximated modal AIC matrix in aeroelastic analysis has also been developed. The method requires the unsteady aerodynamics in frequency domain, and this methodology can be applied to the unsteady subsonic, transonic, and supersonic aerodynamics. The flutter solution can be found by the classic methods, such as rational function approximation, k, p-k, p, root locus et cetera. The unsteady aeroelastic analysis using unsteady subsonic aerodynamic approximation is demonstrated herein. The technique presented is shown to offer consistent flutter speed prediction on an aerostructures test wing (ATW) 2 and a hybrid wing body (HWB) type of vehicle configuration with negligible loss in precision. This method computes AICs that are functions of the changing parameters being studied and are generated within minutes of CPU time instead of hours. These results may have practical application in parametric flutter analyses as well as more efficient multidisciplinary design and optimization studies.

  2. Shape sensitivity analysis of flutter response of a laminated wing

    NASA Technical Reports Server (NTRS)

    Bergen, Fred D.; Kapania, Rakesh K.

    1988-01-01

    A method is presented for calculating the shape sensitivity of a wing aeroelastic response with respect to changes in geometric shape. Yates' modified strip method is used in conjunction with Giles' equivalent plate analysis to predict the flutter speed, frequency, and reduced frequency of the wing. Three methods are used to calculate the sensitivity of the eigenvalue. The first method is purely a finite difference calculation of the eigenvalue derivative directly from the solution of the flutter problem corresponding to the two different values of the shape parameters. The second method uses an analytic expression for the eigenvalue sensitivities of a general complex matrix, where the derivatives of the aerodynamic, mass, and stiffness matrices are computed using a finite difference approximation. The third method also uses an analytic expression for the eigenvalue sensitivities, but the aerodynamic matrix is computed analytically. All three methods are found to be in good agreement with each other. The sensitivities of the eigenvalues were used to predict the flutter speed, frequency, and reduced frequency. These approximations were found to be in good agreement with those obtained using a complete reanalysis.

  3. Flutter suppression and gust alleviation using active controls

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1974-01-01

    The effects of active controls on the suppression of flutter and gust alleviation of two different types of subsonic aircraft (the Arava, twin turboprop STOL transport, and the Westwind twin-jet business transport) are investigated. The active controls are introduced in pairs which include, in any chosen wing strip, a leading-edge (LE) control and a trailing-edge (TE) control. Each control surface is allowed to be driven by a combined linear-rotational sensor system, located on the activated strip. The control law, which translates the sensor signals into control surface rotations, is based on the concept of aerodynamic energy. The results indicate the extreme effectiveness of the active systems in controlling flutter. A single system spanning 10% of the wing semispan made the Arava flutter-free, and a similar active system, for the Westwind aircraft, yielded a reduction of 75% in the maximum bending moment of the wing and a reduction of 90% in the acceleration of the cg of the aircraft. Results for simultaneous activation of several LE - TE systems are presented. Further work needed to bring the investigation to completion is also discussed.

  4. Localization of the origin of the atrioventricular junctional rhythm induced during selective ablation of slow-pathway conduction in patients with atrioventricular node reentrant tachycardia.

    PubMed

    Yu, J C; Lauer, M R; Young, C; Liem, L B; Hou, C; Sung, R J

    1996-05-01

    During radiofrequency catheter ablation of slow atrioventricular node pathway conduction in patients with atrioventricular node reentrant tachycardia, an atrioventricular junction rhythm is frequently observed. The origin and relation to ablation success of this junctional rhythm was examined in this study. By using standard intracardiac electrophysiology techniques, we studied the radiofrequency energy-induced atrioventricular junctional rhythm in 43 consecutive patients with atrioventricular node reentrant tachycardia undergoing selective ablation of slow-pathway conduction. The frequency of atrioventricular junctional activity was correlated with successful and unsuccessful attempts at ablation of slow-pathway conduction. Also, we compared the sequence of retrograde atrial activation of radiofrequency energy-induced atrioventricular junctional beats in a subgroup of 22 patients with the retrograde activation sequence observed during pacing from the right ventricular apex and the site of successful ablation of slow-pathway conduction. A total of 201 radiofrequency-energy applications was delivered in 43 patients with > or = 5 atrioventricular junctional beat(s) induced during 110 (55%) of 201 ablation attempts. Atrioventricular junctional activity was noted during 98% of successful ablations but only 43% of the unsuccessful attempts (sensitivity, 98%; specificity, 57%; negative predictive value, 99%). The mean time to appearance of atrioventricular junctional beats was 8.8 +/- 4.1 sec (mean +/- SD) after the onset of radiofrequency-energy application. In 22 (100%) of 22 patients in whom detailed atrial mapping was performed, the retrograde atrial activation sequence of the radiofrequency-induced atrioventricular junctional beats was earliest in the anterior atrial septum, identical to that seen during pacing from the right ventricular apex. Earliest retrograde atrial activation was at the posterior septum in all patients during pacing from the successful ablation

  5. Atrial Cardiopathy: A Broadened Concept of Left Atrial Thromboembolism Beyond Atrial Fibrillation

    PubMed Central

    Kamel, Hooman; Okin, Peter M.; Longstreth, W. T.; Elkind, Mitchell S.V.; Soliman, Elsayed Z.

    2016-01-01

    Atrial fibrillation (AF) has long been associated with a heightened risk of ischemic stroke and systemic thromboembolism, but recent data require a re-evaluation of our understanding of the nature of this relationship. New findings about the temporal connection between AF and stroke, alongside evidence linking markers of left atrial abnormalities with stroke in the absence of apparent AF, suggest that left atrial thromboembolism may occur even without AF. These observations undermine the hypothesis that the dysrhythmia that defines AF is necessary and sufficient to cause thromboembolism. In this commentary, we instead suggest that the substrate for thromboembolism may often be the anatomic and physiological atrial derangements associated with AF. Therefore, our understanding of cardioembolic stroke may be more complete if we shift our representation of its origin from AF to the concept of atrial cardiopathy. PMID:26021638

  6. Labyrinth Seal Flutter Analysis and Test Validation in Support of Robust Rocket Engine Design

    NASA Technical Reports Server (NTRS)

    El-Aini, Yehia; Park, John; Frady, Greg; Nesman, Tom

    2010-01-01

    High energy-density turbomachines, like the SSME turbopumps, utilize labyrinth seals, also referred to as knife-edge seals, to control leakage flow. The pressure drop for such seals is order of magnitude higher than comparable jet engine seals. This is aggravated by the requirement of tight clearances resulting in possible unfavorable fluid-structure interaction of the seal system (seal flutter). To demonstrate these characteristics, a benchmark case of a High Pressure Oxygen Turbopump (HPOTP) outlet Labyrinth seal was studied in detail. First, an analytical assessment of the seal stability was conducted using a Pratt & Whitney legacy seal flutter code. Sensitivity parameters including pressure drop, rotor-to-stator running clearances and cavity volumes were examined and modeling strategies established. Second, a concurrent experimental investigation was undertaken to validate the stability of the seal at the equivalent operating conditions of the pump. Actual pump hardware was used to construct the test rig, also referred to as the (Flutter Rig). The flutter rig did not include rotational effects or temperature. However, the use of Hydrogen gas at high inlet pressure provided good representation of the critical parameters affecting flutter especially the speed of sound. The flutter code predictions showed consistent trends in good agreement with the experimental data. The rig test program produced a stability threshold empirical parameter that separated operation with and without flutter. This empirical parameter was used to establish the seal build clearances to avoid flutter while providing the required cooling flow metering. The calibrated flutter code along with the empirical flutter parameter was used to redesign the baseline seal resulting in a flutter-free robust configuration. Provisions for incorporation of mechanical damping devices were introduced in the redesigned seal to ensure added robustness

  7. Left Atrial Epicardial Adiposity and Atrial Fibrillation

    PubMed Central

    Batal, Omar; Schoenhagen, Paul; Shao, Mingyuan; Ayyad, Ala Eddin; Van Wagoner, David R.; Halliburton, Sandra S.; Tchou, Patrick J.; Chung, Mina K.

    2010-01-01

    Background Atrial fibrillation (AF) has been linked to inflammatory factors and obesity. Epicardial fat is a source of several inflammatory mediators related to the development of coronary artery disease. We hypothesized that periatrial fat may have a similar role in the development of AF. Methods and Results Left atrium (LA) epicardial fat pad thickness was measured in consecutive cardiac CT angiograms performed for coronary artery disease or AF. Patients were grouped by AF burden: no (n=73), paroxysmal (n=60), or persistent (n=36) AF. In a short-axis view at the mid LA, periatrial epicardial fat thickness was measured at the esophagus (LA-ESO), main pulmonary artery, and thoracic aorta; retrosternal fat was measured in axial view (right coronary ostium level). LA area was determined in the 4-chamber view. LA-ESO fat was thicker in patients with persistent AF versus paroxysmal AF (P=0.011) or no AF (P=0.003). LA area was larger in patients with persistent AF than paroxysmal AF (P=0.004) or without AF (P<0.001). LA-ESO was a significant predictor of AF burden even after adjusting for age, body mass index, and LA area (odds ratio, 5.30; 95% confidence interval, 1.39 to 20.24; P=0.015). A propensity score–adjusted multivariable logistic regression that included age, body mass index, LA area, and comorbidities was also performed and the relationship remained statistically significant (P=0.008). Conclusions Increased posterior LA fat thickness appears to be associated with AF burden independent of age, body mass index, or LA area. Further studies are necessary to examine cause and effect, and if inflammatory, paracrine mediators explain this association. PMID:20504944

  8. The cost of illness of atrial fibrillation: a systematic review of the recent literature.

    PubMed

    Wolowacz, S E; Samuel, M; Brennan, V K; Jasso-Mosqueda, J-G; Van Gelder, I C

    2011-10-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia, its prevalence increasing markedly with age. Atrial fibrillation is strongly associated with increased risk of morbidity, including stroke and thromboembolism. There is growing awareness of the economic burden of AF due to ageing populations and constrained public finances. A systematic review was performed (1990-2009). Cost studies for AF or atrial flutter were included; acute-onset and post-operative AF were excluded. Total, direct, and indirect costs were extracted. Of 875 records retrieved, 37 studies were included. The cost of managing individual AF patients is high. Direct-cost estimates ranged from $2000 to 14,200 per patient-year in the USA and from €450 to 3000 in Europe. This is comparable with other chronic conditions such as diabetes. The direct cost of AF represented 0.9-2.4% of the UK health-care budget in 2000 and had almost doubled over the previous 5 years. Inpatient care accounted for 50-70% of annual direct costs. In the USA, AF hospitalizations alone cost ∼$6.65 billion in 2005. In this first systematic review of the economic burden of AF, hospitalizations consistently represented the major cost driver. Costs and hospitalizations attributable to AF have increased markedly over recent decades and are expected to increase in future due to ageing populations.

  9. Nonequilibrium Ablation of Phenolic Impregnated Carbon Ablator

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih K.; Gokcen, Tahir

    2012-01-01

    In previous work, an equilibrium ablation and thermal response model for Phenolic Impregnated Carbon Ablator was developed. In general, over a wide range of test conditions, model predictions compared well with arcjet data for surface recession, surface temperature, in-depth temperature at multiple thermocouples, and char depth. In this work, additional arcjet tests were conducted at stagnation conditions down to 40 W/sq cm and 1.6 kPa. The new data suggest that nonequilibrium effects become important for ablation predictions at heat flux or pressure below about 80 W/sq cm or 10 kPa, respectively. Modifications to the ablation model to account for nonequilibrium effects are investigated. Predictions of the equilibrium and nonequilibrium models are compared with the arcjet data.

  10. Trends in hospitalization for atrial fibrillation: epidemiology, cost, and implications for the future.

    PubMed

    Sheikh, Azfar; Patel, Nileshkumar J; Nalluri, Nikhil; Agnihotri, Kanishk; Spagnola, Jonathan; Patel, Aashay; Asti, Deepak; Kanotra, Ritesh; Khan, Hafiz; Savani, Chirag; Arora, Shilpkumar; Patel, Nilay; Thakkar, Badal; Patel, Neil; Pau, Dhaval; Badheka, Apurva O; Deshmukh, Abhishek; Kowalski, Marcin; Viles-Gonzalez, Juan; Paydak, Hakan

    2015-01-01

    Atrial fibrillation (AF) is the most prevalent arrhythmia worldwide and the most common arrhythmia leading to hospitalization. Due to a substantial increase in incidence and prevalence of AF over the past few decades, it attributes to an extensive economic and public health burden. The increasing number of hospitalizations, aging population, anticoagulation management, and increasing trend for disposition to a skilled facility are drivers of the increasing cost associated with AF. There has been significant progress in AF management with the release of new oral anticoagulants, use of left atrial catheter ablation, and novel techniques for left atrial appendage closure. In this article, we aim to review the trends in epidemiology, hospitalization, and cost of AF along with its future implications on public health.

  11. Increased atrial arrhythmia susceptibility induced by intense endurance exercise in mice requires TNFα

    PubMed Central

    Aschar-Sobbi, Roozbeh; Izaddoustdar, Farzad; Korogyi, Adam S.; Wang, Qiongling; Farman, Gerrie P.; Yang, FengHua; Yang, Wallace; Dorian, David; Simpson, Jeremy A.; Tuomi, Jari M.; Jones, Douglas L.; Nanthakumar, Kumaraswamy; Cox, Brian; Wehrens, Xander H.T.; Dorian, Paul; Backx, Peter H.

    2015-01-01

    Atrial fibrillation (AF) is the most common supraventricular arrhythmia that, for unknown reasons, is linked to intense endurance exercise. Our studies reveal that 6 weeks of swimming or treadmill exercise improves heart pump function and reduces heart-rates. Exercise also increases vulnerability to AF in association with inflammation, fibrosis, increased vagal tone, slowed conduction velocity, prolonged cardiomyocyte action potentials and RyR2 phosphorylation (CamKII-dependent S2814) in the atria, without corresponding alterations in the ventricles. Microarray results suggest the involvement of the inflammatory cytokine, TNFα, in exercised-induced atrial remodelling. Accordingly, exercise induces TNFα-dependent activation of both NFκB and p38MAPK, while TNFα inhibition (with etanercept), TNFα gene ablation, or p38 inhibition, prevents atrial structural remodelling and AF vulnerability in response to exercise, without affecting the beneficial physiological changes. Our results identify TNFα as a key factor in the pathology of intense exercise-induced AF. PMID:25598495

  12. Multifractal analysis for grading complex fractionated electrograms in atrial fibrillation.

    PubMed

    Orozco-Duque, A; Novak, D; Kremen, V; Bustamante, J

    2015-11-01

    Complex fractionated atrial electrograms provide an important tool for identifying arrhythmogenic substrates that can be used to guide catheter ablation for atrial fibrillation (AF). However, fractionation is a phenomenon that remains unclear. This paper aims to evaluate the multifractal properties of electrograms in AF in order to propose a method based on multifractal analysis able to discriminate between different levels of fractionation. We introduce a new method, the h-fluctuation index (hFI), where h is the generalised Hurst exponent, to extract information from the shape of the multifractal spectrum. Two multifractal frameworks are evaluated: multifractal detrended fluctuation analysis and wavelet transform modulus maxima. hFI is exemplified through its application in synthetic signals, and it is evaluated in a database of electrograms labeled on the basis of four degrees of fractionation. We compare the performance of hFI with other indexes, and find that hFI outperforms them. The results of the study provide evidence that multifractal analysis is useful for studying fractionation phenomena in AF electrograms, and indicate that hFI can be proposed as a tool for grade fractionation associated with the detection of target sites for ablation in AF.

  13. New technologies in treatment of atrial fibrillation in cardiosurgical patients

    NASA Astrophysics Data System (ADS)

    Evtushenko, A. V.; Evtushenko, V. V.; Bykov, A. N.; Sergeev, V. S.; Syryamkin, V. I.; Kistenev, Yu. V.; Anfinogenova, Ya. D.; Smyshlyaev, K. A.; Kurlov, I. O.

    2015-11-01

    The article is devoted to the evaluation of the results of clinical application of penetrating radiofrequency ablation techniques on atrial myocardium. Total operated on 241 patients with valvular heart disease and coronary heart disease complicated with atrial fibrillation. All operations were performed under cardiopulmonary bypass and cardioplegia. The main group consists of 141 patients which were operated using penetrating technique radiofrequency exposure. The control group consisted of 100 patients who underwent surgery with the use of "classical" monopolar RF-ablation technique. Both groups were not significantly different on all counts before surgery. Patients with previous heart surgery were excluded during the selection of candidates for the procedure, due to the presence of adhesions in the pericardium, that do not allow good visualization of left atrium, sufficient to perform this procedure. Penetrating technique has significantly higher efficiency compared to the "classic" technique in the early and long-term postoperative periods. In the early postoperative period, its efficiency is 93%, and in the long term is 88%. The efficacy of "classical" monopolar procedure is below: 86% and 68% respectively.

  14. [Perioperative management of atrial fibrillation].

    PubMed

    Arguis, M J; Navarro, R; Regueiro, A; Arbelo, E; Sierra, P; Sabaté, S; Galán, J; Ruiz, A; Matute, P; Roux, C; Gomar, C; Rovira, I; Mont, L; Fita, G

    2014-05-01

    Atrial fibrillation is a frequent complication in the perioperative period. When it appears there is an increased risk of perioperative morbidity due to stroke, thromboembolism, cardiac arrest, myocardial infarction, anticoagulation haemorrhage, and hospital readmissions. The current article focuses on the recommendations for the management of perioperative atrial fibrillation based on the latest Clinical Practice Guidelines on atrial fibrillation by the European Society of Cardiology and the Spanish Society of Cardiology. This article pays special attention to the preoperative management, as well as to the acute perioperative episode. For this reason, the latest recommendations for the control of cardiac frequency, antiarrhythmic treatment and anticoagulation are included.

  15. An iterative transformation procedure for numerical solution of flutter and similar characteristics-value problems

    NASA Technical Reports Server (NTRS)

    Gossard, Myron L

    1952-01-01

    An iterative transformation procedure suggested by H. Wielandt for numerical solution of flutter and similar characteristic-value problems is presented. Application of this procedure to ordinary natural-vibration problems and to flutter problems is shown by numerical examples. Comparisons of computed results with experimental values and with results obtained by other methods of analysis are made.

  16. Wind Tunnel Measurements for Flutter of a Long-Afterbody Bridge Deck.

    PubMed

    Chen, Zeng-Shun; Zhang, Cheng; Wang, Xu; Ma, Cun-Ming

    2017-02-09

    Bridges are an important component of transportation. Flutter is a self-excited, large amplitude vibration, which may lead to collapse of bridges. It must be understood and avoided. This paper takes the Jianghai Channel Bridge, which is a significant part of the Hong Kong-Zhuhai-Macao Bridge, as an example to investigate the flutter of the bridge deck. Firstly, aerodynamic force models for flutter of bridges were introduced. Then, wind tunnel tests of the bridge deck during the construction and the operation stages, under different wind attack angles and wind velocities, were carried out using a high frequency base balance (HFBB) system and laser displacement sensors. From the tests, the static aerodynamic forces and flutter derivatives of the bridge deck were observed. Correspondingly, the critical flutter wind speeds of the bridge deck were determined based on the derivatives, and they are compared with the directly measured flutter speeds. Results show that the observed derivatives are reasonable and applicable. Furthermore, the critical wind speeds in the operation stage is smaller than those in the construction stage. Besides, the flutter instabilities of the bridge in the construction and the operation stages are good. This study helps guarantee the design and the construction of the Jianghai Channel Bridge, and advances the understanding of flutter of long afterbody bridge decks.

  17. Wind Tunnel Measurements for Flutter of a Long-Afterbody Bridge Deck

    PubMed Central

    Chen, Zeng-Shun; Zhang, Cheng; Wang, Xu; Ma, Cun-Ming

    2017-01-01

    Bridges are an important component of transportation. Flutter is a self-excited, large amplitude vibration, which may lead to collapse of bridges. It must be understood and avoided. This paper takes the Jianghai Channel Bridge, which is a significant part of the Hong Kong-Zhuhai-Macao Bridge, as an example to investigate the flutter of the bridge deck. Firstly, aerodynamic force models for flutter of bridges were introduced. Then, wind tunnel tests of the bridge deck during the construction and the operation stages, under different wind attack angles and wind velocities, were carried out using a high frequency base balance (HFBB) system and laser displacement sensors. From the tests, the static aerodynamic forces and flutter derivatives of the bridge deck were observed. Correspondingly, the critical flutter wind speeds of the bridge deck were determined based on the derivatives, and they are compared with the directly measured flutter speeds. Results show that the observed derivatives are reasonable and applicable. Furthermore, the critical wind speeds in the operation stage is smaller than those in the construction stage. Besides, the flutter instabilities of the bridge in the construction and the operation stages are good. This study helps guarantee the design and the construction of the Jianghai Channel Bridge, and advances the understanding of flutter of long afterbody bridge decks. PMID:28208773

  18. Influence of Shock Wave on the Flutter Behavior of Fan Blades Investigated

    NASA Technical Reports Server (NTRS)

    Srivastava, Rakesh; Bakhle, Milind A.; Stefko, George L.

    2003-01-01

    Modern fan designs have blades with forward sweep; a lean, thin cross section; and a wide chord to improve performance and reduce noise. These geometric features coupled with the presence of a shock wave can lead to flutter instability. Flutter is a self-excited dynamic instability arising because of fluid-structure interaction, which causes the energy from the surrounding fluid to be extracted by the vibrating structure. An in-flight occurrence of flutter could be catastrophic and is a significant design issue for rotor blades in gas turbines. Understanding the flutter behavior and the influence of flow features on flutter will lead to a better and safer design. An aeroelastic analysis code, TURBO, has been developed and validated for flutter calculations at the NASA Glenn Research Center. The code has been used to understand the occurrence of flutter in a forward-swept fan design. The forward-swept fan, which consists of 22 inserted blades, encountered flutter during wind tunnel tests at part speed conditions.

  19. Pulmonary ablation: a primer.

    PubMed

    Roberton, Benjamin J; Liu, David; Power, Mark; Wan, John M C; Stuart, Sam; Klass, Darren; Yee, John

    2014-05-01

    Percutaneous image-guided thermal ablation is safe and efficacious in achieving local control and improving outcome in the treatment of both early stage non-small-cell lung cancer and pulmonary metastatic disease, in which surgical treatment is precluded by comorbidity, poor cardiorespiratory reserve, or unfavorable disease distribution. Radiofrequency ablation is the most established technology, but new thermal ablation technologies such as microwave ablation and cryoablation may offer some advantages. The use of advanced techniques, such as induced pneumothorax and the popsicle stick technique, or combining thermal ablation with radiotherapy, widens the treatment options available to the multidisciplinary team. The intent of this article is to provide the reader with a practical knowledge base of pulmonary ablation by concentrating on indications, techniques, and follow-up.

  20. Renal Ablation Update

    PubMed Central

    Khiatani, Vishal; Dixon, Robert G.

    2014-01-01

    Thermal ablative technologies have evolved considerably in the recent past and are now an important component of current clinical guidelines for the treatment of small renal masses. Both radiofrequency ablation and cryoablation have intermediate-term oncologic control that rivals surgical options, with favorable complication profiles. Studies comparing cryoablation and radiofrequency ablation show no significant difference in oncologic control or complication profile between the two modalities. Early data from small series with microwave ablation have shown similar promising results. Newer technologies including irreversible electroporation and high-intensity–focused ultrasound have theoretical advantages, but will require further research before becoming a routine part of the ablation armamentarium. The purpose of this review article is to discuss the current ablative technologies available, briefly review their mechanisms of action, discuss technical aspects of each, and provide current data supporting their use. PMID:25049445

  1. Parametric Flutter Analysis of the TCA Configuration and Recommendation for FFM Design and Scaling

    NASA Technical Reports Server (NTRS)

    Baker, Myles; Lenkey, Peter

    1997-01-01

    The current HSR Aeroelasticity plan to design, build, and test a full span, free flying transonic flutter model in the TDT has many technical obstacles that must be overcome for a successful program. One technical obstacle is the determination of a suitable configuration and point in the sky to use in setting the scaling point for the ASE models program. Determining this configuration and point in the sky requires balancing several conflicting requirements, including model buildability, tunnel test safety, and the ability of the model to represent the flutter mechanisms of interest. As will be discussed in detail in subsequent sections, the current TCA design exhibits several flutter mechanisms of interest. It has been decided that the ASE models program will focus on the low frequency symmetric flutter mechanism, and will make no attempt to investigate high frequency flutter mechanisms. There are several reasons for this choice. First, it is believed that the high frequency flutter mechanisms are similar in nature to classical wing bending/torsion flutter, and therefore there is more confidence that this mechanism can be predicted using current techniques. The low frequency mode, on the other hand, is a highly coupled mechanism involving wing, body, tail, and engine motion which may be very difficult to predict. Second, the high frequency flutter modes result in very small weight penalties (several hundred pounds), while suppression of the low frequency mechanism inside the flight envelope causes thousands of pounds to be added to the structure. In order to successfully test the low frequency flutter mode of interest, a suitable starting configuration and point in the sky must be identified. The configuration and point in the sky must result in a wind tunnel model that (1) represents the low-frequency wing/body/engine/empennage flutter mechanisms that are unique to HSCT configurations, (2) flutters at an acceptably low frequency in the tunnel, (3) flutters at an

  2. A preliminary study of the effects of vortex diffusers (winglets) on wing flutter

    NASA Technical Reports Server (NTRS)

    Doggett, R. V., Jr.; Farmer, M. G.

    1975-01-01

    Some experimental flutter results are presented for a simple, flat-plate wing model and for the same wing model equipped with two different upper surface vortex diffusers over the Mach number range from about 0.70 to 0.95. Both vortex diffusers had the same planform, but one weighed about 0.3 percent of the basic wing weight, whereas the other weighed about 1.8 percent of the wing weight. The addition of the lighter vortex diffuser reduced the flutter dynamic pressure by about 3 percent; the heavier vortex diffuser reduced the flutter dynamic pressure by about 12 percent. The experimental flutter results are compared at a Mach number of 0.80 with analytical flutter results obtained by using doublet lattice and lifting surface (Kernel function) unsteady aerodynamic theories.

  3. Evaluation of somatosensory cortical differences between flutter and vibration tactile stimuli.

    PubMed

    Han, Sang Woo; Chung, Yoon Gi; Kim, Hyung-Sik; Chung, Soon-Cheol; Park, Jang-Yeon; Kim, Sung-Phil

    2013-01-01

    In parallel with advances in haptic-based mobile computing systems, understanding of the neural processing of vibrotactile information becomes of great importance. In the human nervous system, two types of vibrotactile information, flutter and vibration, are delivered from mechanoreceptors to the somatosensory cortex through segregated neural afferents. To investigate how the somatosensory cortex differentiates flutter and vibration, we analyzed the cortical responses to vibrotactile stimuli with a wide range of frequencies. Specifically, we examined whether cortical activity changed most around 50 Hz, which is known as a boundary between flutter and vibration. We explored various measures to evaluate separability of cortical activity across frequency and found that the hypothesis margin method resulted in the greatest separability between flutter and vibration. This result suggests that flutter and vibration information may be processed by different neural processes in the somatosensory cortex.

  4. Flutter of Winged Space Reentry Vehicles Affected by an Elastic Attachment in Launching Configuration

    NASA Astrophysics Data System (ADS)

    Kanda, Atsushi; Ueda, Tetsuhiko

    This paper reports a flutter investigation of a re-entry space vehicle having an elastic rotational mode caused by its launching rocket. The elastic rotational mode is taken into consideration as an elastic roll mode or an elastic yaw mode. Flutter experiments were conducted in NAL Transonic Wind Tunnel. The DPM (Doublet-Point Method) is used to calculate flutter boundaries. It is shown that the elastic roll mode may lower critical flutter speed, because its existence alters the natural frequency of an anti-symmetric bending mode with which flutter occurs. A coupling between the elastic yaw mode and an anti-symmetric bending mode of a tip-fin wing is also shown to be critical.

  5. Flutter of Winged Reentry Space Vehicles Affected by an Elastic Attachment in Launching Configuration

    NASA Astrophysics Data System (ADS)

    Kanda, Atsushi; Ueda, Tetsuhiko

    This paper reports the flutter investigation of a winged reentry space vehicle having rotational modes in dynamic deflection due to an elastic attachment between a vehicle and a booster rocket. The elastic rotational mode is taken into consideration as an elastic rolling mode or an elastic yawing mode. Flutter experiments have been conducted in a transonic wind tunnel. The doublet-point method (DPM) is used to calculate flutter boundaries for this model. It is shown that an elastic rolling mode may lower the critical speed of anti-symmetric mode flutter because its existence alters the natural vibration mode of anti-symmetric bending which causes flutter. On the other hand, a coupling between an elastic yawing mode and an anti-symmetric bending one becomes critical in the different model.

  6. Developing Uncertainty Models for Robust Flutter Analysis Using Ground Vibration Test Data

    NASA Technical Reports Server (NTRS)

    Potter, Starr; Lind, Rick; Kehoe, Michael W. (Technical Monitor)

    2001-01-01

    A ground vibration test can be used to obtain information about structural dynamics that is important for flutter analysis. Traditionally, this information#such as natural frequencies of modes#is used to update analytical models used to predict flutter speeds. The ground vibration test can also be used to obtain uncertainty models, such as natural frequencies and their associated variations, that can update analytical models for the purpose of predicting robust flutter speeds. Analyzing test data using the -norm, rather than the traditional 2-norm, is shown to lead to a minimum-size uncertainty description and, consequently, a least-conservative robust flutter speed. This approach is demonstrated using ground vibration test data for the Aerostructures Test Wing. Different norms are used to formulate uncertainty models and their associated robust flutter speeds to evaluate which norm is least conservative.

  7. Some considerations on the effects of the P-derivatives on bridge deck flutter

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Brownjohn, James Mark William

    2005-05-01

    Using two degrees of freedom (dof) experimental flutter derivatives to perform three-dimensional flutter analysis for a cable-supported bridge is a widely practiced method. It is important to consider the P-derivatives effect to have more accurate analysis for a long-span bridge. Through a case example, this paper studied some of the issues relating to the P-derivatives effects on flutter. The operational condition in two-dof experiments was discussed. It was suggested that due to the strong aeroelastic coupling effect of the sectional model studied in this research, there was an inherent weakness of two-dof experiments. The effect of the P-derivatives was studied for an example bridge by comparing the flutter analysis results using two-dof and three-dof experimental flutter derivatives.

  8. A computer program for automated flutter solution and matched point determination

    NASA Technical Reports Server (NTRS)

    Bhatia, K. G.

    1973-01-01

    The use of a digital computer program (MATCH) for automated determination of the flutter velocity and the matched-point flutter density is described. The program is based on the use of the modified Laguerre iteration formula to converge to a flutter crossing or a matched-point density. A general description of the computer program is included and the purpose of all subroutines used is stated. The input required by the program and various input options are detailed, and the output description is presented. The program can solve flutter equations formulated with up to 12 vibration modes and obtain flutter solutions for up to 10 air densities. The program usage is illustrated by a sample run, and the FORTRAN program listing is included.

  9. Radiofrequency Ablation of Cancer

    SciTech Connect

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2004-09-15

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized.

  10. Atrial fibrillation and heart failure: is atrial fibrillation a disease?

    PubMed

    Tilman, V

    2014-09-01

    Atrial fibrillation in heart failure often occur together. The relationship between atrial fibrillation and heart failure has remained a subject of research. The main manifestation of the violation of hydrodynamics in heart failure is the increased end-diastolic pressure, which is transmitted through the intercommunicated system (left ventricle-left atrium-pulmonary veins-alveolar capillaries) causing increased pulmonary wedge pressure with the danger for pulmonary edema. End-diastolic pressure is the sum of left ventricle diastolic pressure and left atrial systolic pressure. Stopping the mechanical systole of the left atrium can reduce the pressure in the system in heart failure. Atrial fibrillation stops the mechanical systole of the left atrium and decreases the intercommunicating pressure and pulmonary wedge pressure. It is possible that atrial fibrillation is a mechanism for protection from increasing end-diastolic pressure and pulmonary wedge pressure, and prevents the danger of pulmonary edema. This hypothesis may explain the relationship between heart failure and atrial fibrillation and their frequent association.

  11. Lung Ablation: Whats New?

    PubMed

    Xiong, Lillian; Dupuy, Damian E

    2016-07-01

    Lung cancer had an estimated incidence of 221,200 in 2015, making up 13% of all cancer diagnoses. Tumor ablation is an important treatment option for nonsurgical lung cancer and pulmonary metastatic patients. Radiofrequency ablation has been used for over a decade with newer modalities, microwave ablation, cryoablation, and irreversible electroporation presenting as additional and possibly improved treatment options for patients. This minimally invasive therapy is best for small primary lesions or favorably located metastatic tumors. These technologies can offer palliation and sometimes cure of thoracic malignancies. This article discusses the current available technologies and techniques available for tumor ablation.

  12. Atrial Septal Defect (For Kids)

    MedlinePlus

    ... wall called the septum that normally separates the blue and red blood. In a person with an atrial septal defect, there's an opening in that wall. This hole in the wall lets oxygen-rich blood from ...

  13. Delayed cardiac tamponade: A rare but life-threatening complication of catheter ablation.

    PubMed

    Yetter, Elizabeth; Brazg, Jared; Del Valle, Diane; Mulvey, Laura; Dickman, Eitan

    2016-11-17

    Delayed cardiac tamponade (DCT) is a rare and life-threatening complication of catheter ablation performed as a treatment of atrial fibrillation, with few cases described in the medical literature. We present the case of a 57year-old man presenting with DCT 61days following a catheter ablation procedure. To the best of our knowledge, this is the most delayed case of cardiac tamponade (CT) following catheter ablation described in the literature. We also discuss the importance of point of care ultrasound (POCUS) in the diagnosis and treatment of CT. Emergency physicians must maintain a high index of suspicion in making the diagnosis of CT as patients may present with vague symptoms such as neck or back pain, shortness of breath, fatigue, dizziness, or altered mental status, often without chest pain. Common risk factors for CT include cancer, renal failure, pericarditis, cardiac surgery, myocardial rupture, trauma, and retrograde aortic dissection. In addition, although rare, both catheter ablation and use of anticoagulation carry risks of developing CT. A worldwide survey of medical centers performing catheter ablation found CT as a complication in less than 2% of cases [1]. Some proposed mechanisms of DCT include small pericardial hemorrhages following post-procedural anticoagulation or rupture of the sealed ablation-induced left atrial wall [2]. Clinical examination and electrocardiography may be helpful. However, the criterion standard for diagnosing CT is echocardiography [3].

  14. Ablative Thermal Protection System Fundamentals

    NASA Technical Reports Server (NTRS)

    Beck, Robin A. S.

    2013-01-01

    This is the presentation for a short course on the fundamentals of ablative thermal protection systems. It covers the definition of ablation, description of ablative materials, how they work, how to analyze them and how to model them.

  15. Atrial fibrillation and anabolic steroids.

    PubMed

    Sullivan, M L; Martinez, C M; Gallagher, E J

    1999-01-01

    A young male bodybuilder, consuming large doses of anabolic steroids (AS), presented to the Emergency Department (ED) with symptomatic rapid atrial fibrillation (AF). Echocardiogram revealed significant septal hypokinesis, and posterior and septal wall thickness at the upper limit of normal for highly trained athletes. The atrial fibrillation had not recurred at 10 weeks after discontinuation of AS use. Consumption of these agents in athletes has been associated with hypertension, ischemic heart disease, hypertrophic cardiomyopathy, and sudden death.

  16. Feasibility of in vivo transesophageal cardiac ablation using a phased ultrasound array.

    PubMed

    Werner, Jacob; Park, Eun-Joo; Lee, Hotaik; Francischelli, David; Smith, Nadine Barrie

    2010-05-01

    Over 2.2 million Americans suffer from atrial fibrillation making it one of the most common arrhythmias. Cardiac ablation has shown a high rate of success in treating paroxysmal atrial fibrillation. Prevailing modalities for this treatment are catheter based radio-frequency ablation or surgery. However, there is measurable morbidity and significant costs and time associated with these invasive procedures. Due to these issues, developing a method that is less invasive to treat atrial fibrillation is needed. In the development of such a device, a transesophageal ultrasound applicator for cardiac ablation was designed, constructed and evaluated. A goal of this research was to create lesions in myocardial tissue using a phased array. Based on multiple factors from array simulations, transesophageal imaging devices and throat anatomy, a phased ultrasound transducer that can be inserted into the esophagus was designed and tested. In this research, a two-dimensional sparse phased array with the aperture size of 20.7 mm x 10.2 mm with flat tapered elements as a transesophageal ultrasound applicator was fabricated and evaluated with in vivo experiments. Five pigs were anesthetized; the array was passed through the esophagus and positioned over the heart. The array was operated for 8-15 min at 1.6 MHz with the acoustic intensity of 150-300 W/cm(2) resulting in both single and multiple lesions on atrial and ventricular myocardium. The average size of lesions was 5.1 +/- 2.1 mm in diameter and 7.8 +/- 2.5 mm in length. Based on the experimental results, the array delivered sufficient power to the focal point to produce ablation while not grossly damaging nearby tissue outside the target area. These results demonstrate a potential application of the ultrasound applicator to transesophageal cardiac surgery in atrial fibrillation treatment.

  17. In Vivo Evaluations of a Phased Ultrasound Array for Transesophageal Cardiac Ablation

    NASA Astrophysics Data System (ADS)

    Jaiswal, Devina; Werner, Jacob; Park, Eun-Joo; Francischelli, David; Smith, Nadine Barrie

    2010-03-01

    Atrial fibrillation is one of the most common arrhythmias that affects over 2.2 million Americans each year. Catheter ablation, one of the effective treatments, has shown high rate of success in treating paroxysmal atrial fibrillation. Currently, radiofrequency which is being used for catheter ablation is an invasive procedure. Measurable morbidity and significant costs and time are associated with this modality of treatment of permanent or persistent atrial fibrillation. In order to address these issues, a transesophageal ultrasound applicator for noninvasive cardiac ablation was designed, developed and evaluated. The ultrasound energy delivered by the phased array was used to create a lesion in the myocardial tissue. Various factors, simulation results of transducer arrays, current transesophageal medical devices, and throat anatomy, were considered while designing a phased ultrasound transducer that can be inserted into the esophagus. For this research, a two-dimensional sparse phased array with flat tapered elements was fabricated and evaluated in in vivo experiments. Five pigs were anesthetized; the array was passed transesophagealy and positioned over the heart. An operating frequency of 1.6 MHz and 8˜15 minutes of array operation resulted in both single and multiple lesions on atrial and ventricular myocardium. The average size of lesions was 5.1±2.1 mm in diameter and 7.8±2.5 mm in length. Experimental results indicate that the array delivered sufficient power to produce ablation at the focal point while not grossly damaging the tissue surrounding the area of interest. These results demonstrate a potential application of the ultrasound applicator for noninvasive transesophageal cardiac surgery in atrial fibrillation treatment.

  18. Structural testing for static failure, flutter and other scary things

    NASA Technical Reports Server (NTRS)

    Ricketts, R. H.

    1983-01-01

    Ground test and flight test methods are described that may be used to highlight potential structural problems that occur on aircraft. Primary interest is focused on light-weight general aviation airplanes. The structural problems described include static strength failure, aileron reversal, static divergence, and flutter. An example of each of the problems is discussed to illustrate how the data acquired during the tests may be used to predict the occurrence of the structural problem. While some rules of thumb for the prediction of structural problems are given the report is not intended to be used explicitly as a structural analysis handbook.

  19. Flutter suppression and gust alleviation using active controls

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1975-01-01

    Application of the aerodynamic energy approach to some problems of flutter suppression and gust alleviation were considered. A simple modification of the control-law is suggested for achieving the required pitch control in the use of a leading edge - trailing edge activated strip. The possible replacement of the leading edge - trailing edge activated strip by a trailing edge - tab strip is also considered as an alternate solution. Parameters affecting the performance of the activated leading edge - trailing edge strip were tested on the Arava STOL Transport and the Westwind Executive Jet Transport and include strip location, control-law gains and a variation in the control-law itself.

  20. Contributions of Transonic Dynamics Tunnel Testing to Airplane Flutter Clearance

    NASA Technical Reports Server (NTRS)

    Rivera, Jose A.; Florance, James R.

    2000-01-01

    The Transonic Dynamics Tunnel (TDT) became in operational in 1960, and since that time has achieved the status of the world's premier wind tunnel for testing large in aeroelastically scaled models at transonic speeds. The facility has many features that contribute to its uniqueness for aeroelastic testing. This paper will briefly describe these capabilities and features, and their relevance to aeroelastic testing. Contributions to specific airplane configurations and highlights from the flutter tests performed in the TDT aimed at investigating the aeroelastic characteristics of these configurations are presented.

  1. Real-time flutter identification with close mode resolution

    NASA Technical Reports Server (NTRS)

    Roy, R. H.; Walker, R. A.; Gilyard, G. B.

    1986-01-01

    Real-time flutter prediction including close modes can be effectively estimated from turbulence or on-board excitation with an Extended Kalman Filter (EKF) approach. A physically based model form enables prediction of the damping rate as well as damping, giving a time to instability estimate with its variance. The approach is recursive and can operate asynchronously to drop data outliers and hence is quite robust. Its speed is reasonable for on-line application but can also be used effectively as an off-line analysis tool for application to any modal testing situation.

  2. Aeroelastic Tailoring of Transport Wings Including Transonic Flutter Constraints

    NASA Technical Reports Server (NTRS)

    Stanford, Bret K.; Wieseman, Carol D.; Jutte, Christine V.

    2015-01-01

    Several minimum-mass optimization problems are solved to evaluate the effectiveness of a variety of novel tailoring schemes for subsonic transport wings. Aeroelastic stress and panel buckling constraints are imposed across several trimmed static maneuver loads, in addition to a transonic flutter margin constraint, captured with aerodynamic influence coefficient-based tools. Tailoring with metallic thickness variations, functionally graded materials, balanced or unbalanced composite laminates, curvilinear tow steering, and distributed trailing edge control effectors are all found to provide reductions in structural wing mass with varying degrees of success. The question as to whether this wing mass reduction will offset the increased manufacturing cost is left unresolved for each case.

  3. Semi-actuator disk theory for compressor choke flutter

    NASA Technical Reports Server (NTRS)

    Micklow, J.; Jeffers, J.

    1981-01-01

    A mathematical anaysis predict the unsteady aerodynamic utilizing semi actuator theory environment for a cascade of airfoils harmonically oscillating in choked flow was developed. A normal shock is located in the blade passage, its position depending on the time dependent geometry, and pressure perturbations of the system. In addition to shock dynamics, the model includes the effect of compressibility, interblade phase lag, and an unsteady flow field upstream and downstream of the cascade. Calculated unsteady aerodynamics were compared with isolated airfoil wind tunnel data, and choke flutter onset boundaries were compared with data from testing of an F100 high pressure compressor stage.

  4. New Flutter Analysis Technique for Time-Domain Computational Aeroelasticity

    NASA Technical Reports Server (NTRS)

    Pak, Chan-Gi; Lung, Shun-Fat

    2017-01-01

    A new time-domain approach for computing flutter speed is presented. Based on the time-history result of aeroelastic simulation, the unknown unsteady aerodynamics model is estimated using a system identification technique. The full aeroelastic model is generated via coupling the estimated unsteady aerodynamic model with the known linear structure model. The critical dynamic pressure is computed and used in the subsequent simulation until the convergence of the critical dynamic pressure is achieved. The proposed method is applied to a benchmark cantilevered rectangular wing.

  5. A brief overview of surgery for atrial fibrillation

    PubMed Central

    2014-01-01

    The Maze procedure was the first surgical technique developed to ablate, rather than isolate, atrial fibrillation and was first performed clinically in 1987. The experimental and clinical electrophysiological maps on which the Maze procedure was based demonstrated the presence of two or more large (5-6 cm diameter) macro-reentrant circuits during established atrial fibrillation (AF). Eleven years later, focal triggers were identified, primarily in and around the pulmonary veins, and were shown to be responsible for the induction of individual episodes of AF. Thus, it became clear that episodes of paroxysmal AF could be treated in most patients by isolating or ablating the region of the pulmonary veins, but that once AF became non-paroxysmal and thus dependent upon the macro-reentrant circuits for its maintenance, it would still be necessary to perform some type of additional procedure to interrupt those circuits. Approximately 100,000 patients who undergo coronary artery bypass grafting (CABG), aortic valve replacement (AVR) or mitral valve surgery in the US also have associated AF, but only 20% of them undergo a concomitant procedure to ablate the AF. However, multiple studies have demonstrated that treating the AF at the time of these other primary operations results in an improved quality of life, fewer long-term strokes and improved long-term survival while adding no risk to the overall surgical procedure. Moreover, the major cardiology and surgery societies recommend that concomitant AF surgery be performed in all cases when feasible. Patients undergoing CABG and AVR who have paroxysmal AF should undergo pulmonary vein isolation, while those with non-paroxysmal AF (persistent or long-standing persistent AF) should have a Maze procedure. Patients undergoing mitral valve surgery who have either paroxysmal AF or non-paroxysmal AF should undergo a Maze procedure. PMID:24516803

  6. Robotic magnetic navigation for ablation of human arrhythmias

    PubMed Central

    Da Costa, Antoine; Guichard, Jean Baptiste; Roméyer-Bouchard, Cécile; Gerbay, Antoine; Isaaz, Karl

    2016-01-01

    Radiofrequency treatment represents the first choice of treatment for arrhythmias, in particular complex arrhythmias and especially atrial fibrillation, due to the greater benefit/risk ratio compared to antiarrhythmic drugs. However, complex arrhythmias such as atrial fibrillation require long procedures with additional risks such as X-ray exposure or serious complications such as tamponade. Given this context, the treatment of arrhythmias using robotic magnetic navigation entails a technique well suited to complex arrhythmias on account of its efficacy, reliability, significant reduction in X-ray exposure for both patient and operator, as well as a very low risk of perforation. As ongoing developments will likely improve results and procedure times, this technology will become one of the most modern technologies for treating arrhythmias. Based on the literature, this review summarizes the advantages and limitations of robotic magnetic navigation for ablation of human arrhythmias. PMID:27698569

  7. Sprayable lightweight ablative coating

    NASA Technical Reports Server (NTRS)

    Simpson, William G. (Inventor); Sharpe, Max H. (Inventor); Hill, William E. (Inventor)

    1991-01-01

    An improved lightweight, ablative coating is disclosed that may be spray applied and cured without the development of appreciable shrinkage cracks. The ablative mixture consists essentially of phenolic microballoons, hollow glass spheres, glass fibers, ground cork, a flexibilized resin binder, and an activated colloidal clay.

  8. The impact of 6 weeks of atrial fibrillation on left atrial and ventricular structure and function

    PubMed Central

    Kazui, Toshinobu; Henn, Mathew C.; Watanabe, Yoshiyuki; Kovács, Sándor J.; Lawrance, Christopher P.; Greenberg, Jason W.; Moon, Marc; Schuessler, Richard B.; Damiano, Ralph J.

    2015-01-01

    Objective The impact of prolonged episodes of atrial fibrillation on atrial and ventricular function has been incompletely characterized. The purpose of this study was to investigate the influence of atrial fibrillation on left atrial and ventricular function in a rapid paced porcine model of atrial fibrillation. Methods A control group of pigs (group 1, n = 8) underwent left atrial and left ventricular conductance catheter studies and fibrosis analysis. A second group (group 2, n = 8) received a baseline cardiac magnetic resonance imaging to characterize left atrial and left ventricular function. The atria were rapidly paced into atrial fibrillation for 6 weeks followed by cardioversion and cardiac magnetic resonance imaging. Results After 6 weeks of atrial fibrillation, left atrial contractility defined by atrial end-systolic pressure-volume relationship slope was significantly lower in group 2 than in group 1 (1.1 ± 0.5 vs 1.7 ± 1.0; P = .041), whereas compliance from the end-diastolic pressure-volume relationship was unchanged (1.5 ± 0.9 vs 1.6 ± 1.3; P = .733). Compared with baseline, atrial fibrillation resulted in a significantly higher contribution of left atrial reservoir volume to stroke volume (32% vs 17%; P = .005) and lower left atrial booster pump volume contribution to stroke volume (19% vs 28%; P = .029). Atrial fibrillation also significantly increased maximum left atrial volume (206 ± 41 mL vs 90 ± 21 mL; P < .001). Left atrial fibrosis in group 2 was significantly higher than in group 1. Atrial fibrillation decreased left ventricular ejection fraction (29% ± 9% vs 58 ± 8%; P < .001), but left ventricular stroke volume was unchanged. Conclusions In a chronic model of atrial fibrillation, the left atrium demonstrated significant structural remodeling and decreased contractility. These data suggest that early intervention in patients with persistent atrial fibrillation might mitigate against adverse atrial and ventricular structural

  9. Right atrial tunnel to the left atrial appendage: a danger during balloon septostomy.

    PubMed

    Waldman, J D; McFeeley, P; Bornikova, L

    2001-01-01

    Right atrial tunnel to the left atrial appendage is a very rare anomaly not previously described. Per se, it has no physiological significance but is a source of potential disaster during balloon atrial septostomy. The precise anatomy is demonstrated and ways are proposed to avoid tearing the atrial wall during therapeutic cardiac catheterization.

  10. Insights into energy delivery to myocardial tissue during radiofrequency ablation through application of the first law of thermodynamics.

    PubMed

    Bunch, T Jared; Day, John D; Packer, Douglas L

    2009-04-01

    The approach to catheter-based radiofrequency ablation of atrial fibrillation has evolved, and as a consequence, more energy is delivered in the posterior left atrium, exposing neighboring tissue to untoward thermal injury. Simultaneously, catheter technology has advanced to allow more efficient energy delivery into the myocardium, which compounds the likelihood of collateral injury. This review focuses on the basic principles of thermodynamics as they apply to energy delivery during radiofrequency ablation. These principles can be used to titrate energy delivery and plan ablative approaches in an effort to minimize complications during the procedure.

  11. Left atrial volume assessment in atrial fibrillation using multimodality imaging: a comparison of echocardiography, invasive three-dimensional CARTO and cardiac magnetic resonance imaging.

    PubMed

    Rabbat, Mark G; Wilber, David; Thomas, Kevin; Malick, Owais; Bashir, Atif; Agrawal, Anoop; Biswas, Santanu; Sanagala, Thriveni; Syed, Mushabbar A

    2015-06-01

    Left atrial size in atrial fibrillation is a strong predictor of successful ablation and cardiovascular events. Cardiac magnetic resonance multislice method (CMR-MSM) is the current gold standard for left atrial volume (LAV) assessment but is time consuming. We investigated whether LAV with more rapid area-length method by echocardiography (Echo-AL) or cardiac magnetic resonance (CMR-AL) and invasive measurement by 3D-CARTO mapping during ablation correlate with the CMR-MSM. We studied 250 consecutive patients prior to atrial fibrillation ablation. CMR images were acquired on 3T scanner to measure LAV by MSM and biplane area-length method. Standard echocardiography views were used to calculate LAV by biplane area-length method. LAV during ablation was measured by 3D-CARTO mapping. LAV was compared using intra-class correlation (ICC), Pearson's correlation and Bland-Altman plots. CMR-MSM was used as the reference standard. Mean LAV using CMR-MSM was 112.7 ± 36.7 ml. CMR-AL method overestimated LAV by 13.3 ± 21.8 ml (11.2%, p < 0.005) whereas 3D-CARTO and Echo-AL underestimated LAV by 8.3 ± 22.6 and 24.0 ± 27.6 ml respectively (8.7% and 20.0% respectively, p < 0.005). There was no significant difference between paroxysmal and persistent atrial fibrillation. CMR-AL and 3D-CARTO correlated and agreed well with CMR-MSM (r = 0.87 and 0.74, ICC = 0.80 and 0.77 respectively). However, Echo-AL had poor correlation and agreement with CMR-MSM (r = 0.66 and ICC = 0.48). Bland-Altman plots confirmed these findings. CMR-AL method may be used as an alternative to CMR-MSM, as it is non-invasive, rapid, and correlates well with CMR-MSM. LAV by different modalities should not be used interchangeably.

  12. Dynamic approximate entropy electroanatomic maps detect rotors in a simulated atrial fibrillation model.

    PubMed

    Ugarte, Juan P; Orozco-Duque, Andrés; Tobón, Catalina; Kremen, Vaclav; Novak, Daniel; Saiz, Javier; Oesterlein, Tobias; Schmitt, Clauss; Luik, Armin; Bustamante, John

    2014-01-01

    There is evidence that rotors could be drivers that maintain atrial fibrillation. Complex fractionated atrial electrograms have been located in rotor tip areas. However, the concept of electrogram fractionation, defined using time intervals, is still controversial as a tool for locating target sites for ablation. We hypothesize that the fractionation phenomenon is better described using non-linear dynamic measures, such as approximate entropy, and that this tool could be used for locating the rotor tip. The aim of this work has been to determine the relationship between approximate entropy and fractionated electrograms, and to develop a new tool for rotor mapping based on fractionation levels. Two episodes of chronic atrial fibrillation were simulated in a 3D human atrial model, in which rotors were observed. Dynamic approximate entropy maps were calculated using unipolar electrogram signals generated over the whole surface of the 3D atrial model. In addition, we optimized the approximate entropy calculation using two real multi-center databases of fractionated electrogram signals, labeled in 4 levels of fractionation. We found that the values of approximate entropy and the levels of fractionation are positively correlated. This allows the dynamic approximate entropy maps to localize the tips from stable and meandering rotors. Furthermore, we assessed the optimized approximate entropy using bipolar electrograms generated over a vicinity enclosing a rotor, achieving rotor detection. Our results suggest that high approximate entropy values are able to detect a high level of fractionation and to locate rotor tips in simulated atrial fibrillation episodes. We suggest that dynamic approximate entropy maps could become a tool for atrial fibrillation rotor mapping.

  13. MAVRIC Flutter Model Transonic Limit Cycle Oscillation Test

    NASA Technical Reports Server (NTRS)

    Edwards, John W.; Schuster, David M.; Spain, Charles V.; Keller, Donald F.; Moses, Robert W.

    2001-01-01

    The Models for Aeroelastic Validation Research Involving Computation semi-span wind-tunnel model (MAVRIC-I), a business jet wing-fuselage flutter model, was tested in NASA Langley's Transonic Dynamics Tunnel with the goal of obtaining experimental data suitable for Computational Aeroelasticity code validation at transonic separation onset conditions. This research model is notable for its inexpensive construction and instrumentation installation procedures. Unsteady pressures and wing responses were obtained for three wingtip configurations of clean, tipstore, and winglet. Traditional flutter boundaries were measured over the range of M = 0.6 to 0.9 and maps of Limit Cycle Oscillation (LCO) behavior were made in the range of M = 0.85 to 0.95. Effects of dynamic pressure and angle-of-attack were measured. Testing in both R134a heavy gas and air provided unique data on Reynolds number, transition effects, and the effect of speed of sound on LCO behavior. The data set provides excellent code validation test cases for the important class of flow conditions involving shock-induced transonic flow separation onset at low wing angles, including LCO behavior.

  14. Rapid Aeroelastic Analysis of Blade Flutter in Turbomachines

    NASA Technical Reports Server (NTRS)

    Trudell, J. J.; Mehmed, O.; Stefko, G. L.; Bakhle, M. A.; Reddy, T. S. R.; Montgomery, M.; Verdon, J.

    2006-01-01

    The LINFLUX-AE computer code predicts flutter and forced responses of blades and vanes in turbomachines under subsonic, transonic, and supersonic flow conditions. The code solves the Euler equations of unsteady flow in a blade passage under the assumption that the blades vibrate harmonically at small amplitudes. The steady-state nonlinear Euler equations are solved by a separate program, then equations for unsteady flow components are obtained through linearization around the steady-state solution. A structural-dynamics analysis (see figure) is performed to determine the frequencies and mode shapes of blade vibrations, a preprocessor interpolates mode shapes from the structural-dynamics mesh onto the LINFLUX computational-fluid-dynamics mesh, and an interface code is used to convert the steady-state flow solution to a form required by LINFLUX. Then LINFLUX solves the linearized equations in the frequency domain to calculate the unsteady aerodynamic pressure distribution for a given vibration mode, frequency, and interblade phase angle. A post-processor uses the unsteady pressures to calculate generalized aerodynamic forces, response amplitudes, and eigenvalues (which determine the flutter frequency and damping). In comparison with the TURBO-AE aeroelastic-analysis code, which solves the equations in the time domain, LINFLUX-AE is 6 to 7 times faster.

  15. Fluttering energy harvesters in the wind: A review

    NASA Astrophysics Data System (ADS)

    McCarthy, J. M.; Watkins, S.; Deivasigamani, A.; John, S. J.

    2016-01-01

    The growing area of harvesting energy by aerodynamically induced flutter in a fluid stream is reviewed. Numerous approaches were found to understand, demonstrate and [sometimes] optimise harvester performance based on Movement-Induced or Extraneously Induced Excitation. Almost all research was conducted in smooth, unidirectional flow domains; either experimental or computational. The power outputs were found to be very low when compared to conventional wind turbines, but potential advantages could be lower noise levels. A consideration of the likely outdoor environment for fluttering harvesters revealed that the flow would be highly turbulent and having a mean flow angle in the horizontal plane that could approach a harvester from any direction. Whilst some multiple harvester systems in smooth, well-aligned flow found enhanced efficiency (due to beneficial wake interaction) this would require an invariant flow approach angle. It was concluded that further work needs to be performed to find a universally accepted metric for efficiency and to understand the effects of the realities of the outdoors, including the highly variable and turbulent flow conditions likely to be experienced.

  16. Chirality-dependent flutter of Typha blades in wind

    PubMed Central

    Zhao, Zi-Long; Liu, Zong-Yuan; Feng, Xi-Qiao

    2016-01-01

    Cattail or Typha, an emergent aquatic macrophyte widely distributed in lakes and other shallow water areas, has slender blades with a chiral morphology. The wind-resilient Typha blades can produce distinct hydraulic resistance for ecosystem functions. However, their stem may rupture and dislodge in excessive wind drag. In this paper, we combine fluid dynamics simulations and experimental measurements to investigate the aeroelastic behavior of Typha blades in wind. It is found that the chirality-dependent flutter, including wind-induced rotation and torsion, is a crucial strategy for Typha blades to accommodate wind forces. Flow visualization demonstrates that the twisting morphology of blades provides advantages over the flat one in the context of two integrated functions: improving wind resistance and mitigating vortex-induced vibration. The unusual dynamic responses and superior mechanical properties of Typha blades are closely related to their biological/ecosystem functions and macro/micro structures. This work decodes the physical mechanisms of chirality-dependent flutter in Typha blades and holds potential applications in vortex-induced vibration suppression and the design of, e.g., bioinspired flight vehicles. PMID:27432079

  17. Blade row interaction effects on flutter and forced response

    NASA Technical Reports Server (NTRS)

    Buffum, Daniel H.

    1993-01-01

    In the flutter or forced response analysis of a turbomachine blade row, the blade row in question is commonly treated as if it is isolated from the neigboring blade rows. Disturbances created by vibrating blades are then free to propagate away from this blade row without being disturbed. In reality, neighboring blade rows will reflect some portion of this wave energy back toward the vibrating blades, causing additional unsteady forces on them. It is of fundamental importance to determine whether or not these reflected waves can have a significant effect on the aeroelastic stability or forced response of a blade row. Therefore, a procedure to calculate intra-blade-row unsteady aerodynamic interactions was developed which relies upon results available from isolated blade row unsteady aerodynamic analyses. In addition, an unsteady aerodynamic influence coefficient technique is used to obtain a model for the vibratory response in which the neighboring blade rows are also flexible. The flutter analysis shows that interaction effects can be destabilizing, and the forced response analysis shows that interaction effects can result in a significant increase in the resonant response of a blade row.

  18. Effects of leading-edge tubercles on wing flutter speeds.

    PubMed

    Ng, B F; New, T H; Palacios, R

    2016-04-12

    The dynamic aeroelastic effects on wings modified with bio-inspired leading-edge (LE) tubercles are examined in this study. We adopt a state-space aeroelastic model via the coupling of unsteady vortex-lattice method and a composite beam to evaluate stability margins as a result of LE tubercles on a generic wing. The unsteady aerodynamics and spanwise mass variations due to LE tubercles have counteracting effects on stability margins with the former having dominant influence. When coupled, flutter speed is observed to be 5% higher, and this is accompanied by close to 6% decrease in reduced frequencies as an indication of lower structural stiffness requirements for wings with LE tubercles. Both tubercle amplitude and wavelength have similar influences over the change in flutter speeds, and such modifications to the LE would have minimal effect on stability margins when concentrated inboard of the wing. Lastly, when used in sweptback wings, LE tubercles are observed to have smaller impacts on stability margins as the sweep angle is increased.

  19. Panel flutter in a low-density atmosphere

    NASA Technical Reports Server (NTRS)

    Resende, Hugo B.

    1991-01-01

    The problem of panel flutter is considered in the case of a free-molecule flow, the effect of the aerodynamic shear stress being incorporated into the structural model through distributed longitudinal and bending moment loads. This kind of analysis is relevant in the case of hypersonic flight vehicles, like the NASP, especially because in these conditions the shear stress can be expected to be considerably larger that the pressure at a given point. The aerodynamic loading is derived assuming a quasi-steady approximation. Two important parameters are given by alpha-m, the 'momentum accommodation coefficient', and Theta, the temperature ratio between the panel temperature and the temperature of the undisturbed flow. For high enough values of Theta the variation of the linear flutter parameter with alpha-m is close to linear. Comparison with continuum theory, given by linear piston theory, depends on the values of Theta and alpha-m considered. Finally, it is shown that buckling with respect to a uniform distributed longitudinal load is stabilizing.