Automatic generation of endocardial surface meshes with 1-to-1 correspondence from cine-MR images

NASA Astrophysics Data System (ADS)

Su, Yi; Teo, S.-K.; Lim, C. W.; Zhong, L.; Tan, R. S.

2015-03-01

In this work, we develop an automatic method to generate a set of 4D 1-to-1 corresponding surface meshes of the left ventricle (LV) endocardial surface which are motion registered over the whole cardiac cycle. These 4D meshes have 1- to-1 point correspondence over the entire set, and is suitable for advanced computational processing, such as shape analysis, motion analysis and finite element modelling. The inputs to the method are the set of 3D LV endocardial surface meshes of the different frames/phases of the cardiac cycle. Each of these meshes is reconstructed independently from border-delineated MR images and they have no correspondence in terms of number of vertices/points and mesh connectivity. To generate point correspondence, the first frame of the LV mesh model is used as a template to be matched to the shape of the meshes in the subsequent phases. There are two stages in the mesh correspondence process: (1) a coarse matching phase, and (2) a fine matching phase. In the coarse matching phase, an initial rough matching between the template and the target is achieved using a radial basis function (RBF) morphing process. The feature points on the template and target meshes are automatically identified using a 16-segment nomenclature of the LV. In the fine matching phase, a progressive mesh projection process is used to conform the rough estimate to fit the exact shape of the target. In addition, an optimization-based smoothing process is used to achieve superior mesh quality and continuous point motion.

Evaluating the roles of detailed endocardial structures on right ventricular haemodynamics by means of CFD simulations.

PubMed

Sacco, Federica; Paun, Bruno; Lehmkuhl, Oriol; Iles, Tinen L; Iaizzo, Paul A; Houzeaux, Guillaume; Vázquez, Mariano; Butakoff, Constantine; Aguado-Sierra, Jazmin

2018-06-11

Computational modelling plays an important role in right ventricular (RV) haemodynamic analysis. However, current approaches employ smoothed ventricular anatomies. The aim of this study is to characterise RV haemodynamics including detailed endocardial structures like trabeculae, moderator band and papillary muscles (PMs). Four paired detailed and smoothed RV endocardium models (two male and two female) were reconstructed from ex-vivo human hearts high-resolution magnetic resonance images (MRI). Detailed models include structures with ≥1 mm 2 cross-sectional area. Haemodynamic characterisation was done by computational fluid dynamics (CFD) simulations with steady and transient inflows, using high performance computing (HPC). The differences between the flows in smoothed and detailed models were assessed using Q-criterion for vorticity quantification, the pressure drop between inlet and outlet, and the wall shear stress (WSS). Results demonstrated that detailed endocardial structures increase the degree of intra-ventricular pressure drop, decrease the WSS and disrupt the dominant vortex creating secondary small vortices. Increasingly turbulent blood flow was observed in the detailed RVs. Female RVs were less trabeculated and presented lower pressure drops than the males. In conclusion, neglecting endocardial structures in RV haemodynamic models may lead to inaccurate conclusions about the pressures, stresses, and blood flow behaviour in the cavity. This article is protected by copyright. All rights reserved.

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

PubMed

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

2013-04-01

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

In vivo evaluation of virtual electrode mapping and ablation utilizing a direct endocardial visualization ablation catheter.

PubMed

Chik, William W B; Barry, M A; Malchano, Zach; Wylie, Bryan; Pouliopoulos, Jim; Huang, Kaimin; Lu, Juntang; Thavapalachandran, Sujitha; Robinson, David; Saadat, Vahid; Thomas, Stuart P; Ross, David L; Kovoor, Pramesh; Thiagalingam, Aravinda

2012-01-01

Radiofrequency (RF) ablation utilizing direct endocardial visualization (DEV) requires a "virtual electrode" to deliver RF energy while preserving visualization. This study aimed to: (1) examine the virtual electrode RF ablation efficacy; (2) determine the optimal power and duration settings; and (3) evaluate the utility of virtual electrode unipolar electrograms. The DEV catheter lesions were compared to lesions formed using a 3.5 mm open irrigated tip catheter within the right atria of 12 sheep. Generator power settings for DEV were titrated from 12W, 14W and 16W for 20, 30 and 40 seconds duration with 25 mL/min saline irrigation. Standard irrigated tip catheter settings of 30W, 50°C for 30 seconds and 30 mL/min were used. The DEV lesions were significantly greater in surface area and both major and minor axes compared to irrigated tip lesions (surface area 19.43 ± 9.09 vs 10.88 ± 4.72 mm, P<0.01) with no difference in transmurality (93/94 vs 46/47) or depth (1.86 ± 0.75 vs 1.85 ± 0.57 mm). Absolute electrogram amplitude reduction was greater for DEV lesions (1.89 ± 1.31 vs 1.49 ± 0.78 mV, P = 0.04), but no difference in percentage reduction. Pre-ablation pacing thresholds were not different between DEV (0.79 ± 0.36 mA) and irrigated tip (0.73 ± 0.25 mA) lesions. There were no complications noted during ablation with either catheter. Virtual electrode ablation consistently created wider lesions at lower power compared to irrigated tip ablation. Virtual electrode electrograms showed a comparable pacing and sensing efficacy in detecting local myocardial electrophysiological changes. © 2011 Wiley Periodicals, Inc.

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

PubMed

Osadchii, O E

2012-08-01

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

Highly trabeculated structure of the human endocardium underlies asymmetrical response to low-energy monophasic shocks

NASA Astrophysics Data System (ADS)

Connolly, Adam; Robson, Matthew D.; Schneider, Jürgen; Burton, Rebecca; Plank, Gernot; Bishop, Martin J.

2017-09-01

Novel low-energy defibrillation therapies are thought to be driven by virtual-electrodes (VEs), due to the interaction of applied monophasic electric shocks with fine-scale anatomical structures within the heart. Significant inter-species differences in the cardiac (micro)-anatomy exist, however, particularly with respect to the degree of endocardial trabeculations, which may underlie important differences in response to low-energy defibrillation protocols. Understanding the interaction of monophasic electric fields with the specific human micro-anatomy is therefore imperative in facilitating the translation and optimisation of these promising experimental therapies to the clinic. In this study, we sought to investigate how electric fields from implanted devices interact with the highly trabeculated human endocardial surface to better understand shock success in order to help optimise future clinical protocols. A bi-ventricular human computational model was constructed from high resolution (350 μm) ex-vivo MR data, including anatomically accurate endocardial structures. Monophasic shocks were applied between a basal right ventricular catheter and an exterior ground. Shocks of varying strengths were applied with both anodal [positive right ventricle (RV) electrode] and cathodal (negative RV electrode) polarities at different states of tissue refractoriness and during induced arrhythmias. Anodal shocks induced isolated positive VEs at the distal side of "detached" trabeculations, which rapidly spread into hyperpolarised tissue on the surrounding endocardial surfaces following the shock. Anodal shocks thus depolarised more tissue 10 ms after the shock than cathodal shocks where the propagation of activation from VEs induced on the proximal side of "detached" trabeculations was prevented due to refractory endocardium. Anodal shocks increased arrhythmia complexity more than cathodal shocks during failed anti-arrhythmia shocks. In conclusion, multiple detached trabeculations in the human ventricle interact with anodal stimuli to induce multiple secondary sources from VEs, facilitating more rapid shock-induced ventricular excitation compared to cathodal shocks. Such a mechanism may help explain inter-species differences in response to shocks and help to develop novel defibrillation strategies.

Epicardial-endocardial breakthrough during stable atrial macroreentry: Evidence from ultra-high-resolution 3-dimensional mapping.

PubMed

Pathik, Bhupesh; Lee, Geoffrey; Sacher, Frédéric; Haïssaguerre, Michel; Jaïs, Pierre; Massoullié, Grégoire; Derval, Nicolas; Sanders, Prashanthan; Kistler, Peter; Kalman, Jonathan M

2017-08-01

Evidence for epicardial-endocardial breakthrough (EEB) is derived from mapping inferences in patients with atrial fibrillation who may also have focal activations. The purpose of this study was to investigate whether EEB could be discerned during stable right atrial (RA) macroreentry using high-density high-spatial resolution 3-dimensional mapping. Macroreentry was diagnosed using 3-dimensional mapping and entrainment. Bipolar maps were reviewed for EEB defined as (1) presence of focal endocardial activation with radial spread unaccounted for by an endocardial wavefront and (2) present with the same timing on every tachycardia cycle. The EEB site was always in proximity to a line of endocardial conduction slowing or block. Distance and conduction velocity from the line of block to the EEB site was calculated. Electrograms at EEB sites were individually analyzed for morphology and to confirm direction of activation. Entrainment was performed at EEB sites. Twenty-six patients were studied. Fourteen examples of EEB were seen: 11 at the posterior RA (4 at the superior portion of the posterior wall and 7 at the inferior section) and 1 each at the cavotricuspid isthmus postablation, RA septum, and inferolateral RA. The mean area of the EEB site was 0.6 ± 0.2 cm 2 . A mean of 79.5% ± 18.6% of unipolar electrograms at the EEB site demonstrated an rS morphology. The mean distance and conduction velocity from the line of endocardial block to the EEB site at the posterior RA was 13.6 ± 2.3 mm and 59.3 ± 12.3 cm/s, respectively. In 4 patients, entrainment demonstrated that EEB sites were within the circuit and in 1 of these patients critical to arrhythmia maintenance. Activation maps during tachycardia and coronary sinus pacing demonstrated EEB at the same anatomic site. EEB sites were demonstrated in stable atrial macroreentry supported by systematic entrainment confirmation and demonstration of the same phenomenon during pacing. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Reduction in Left Ventricular Wall Stress and Improvement in Function in Failing Hearts using Algisyl-LVR

PubMed Central

Lee, Lik Chuan; Zhihong, Zhang; Hinson, Andrew; Guccione, Julius M.

2013-01-01

Injection of Algisyl-LVR, a treatment under clinical development, is intended to treat patients with dilated cardiomyopathy. This treatment was recently used for the first time in patients who had symptomatic heart failure. In all patients, cardiac function of the left ventricle (LV) improved significantly, as manifested by consistent reduction of the LV volume and wall stress. Here we describe this novel treatment procedure and the methods used to quantify its effects on LV wall stress and function. Algisyl-LVR is a biopolymer gel consisting of Na+-Alginate and Ca2+-Alginate. The treatment procedure was carried out by mixing these two components and then combining them into one syringe for intramyocardial injections. This mixture was injected at 10 to 19 locations mid-way between the base and apex of the LV free wall in patients. Magnetic resonance imaging (MRI), together with mathematical modeling, was used to quantify the effects of this treatment in patients before treatment and at various time points during recovery. The epicardial and endocardial surfaces were first digitized from the MR images to reconstruct the LV geometry at end-systole and at end-diastole. Left ventricular cavity volumes were then measured from these reconstructed surfaces. Mathematical models of the LV were created from these MRI-reconstructed surfaces to calculate regional myofiber stress. Each LV model was constructed so that 1) it deforms according to a previously validated stress-strain relationship of the myocardium, and 2) the predicted LV cavity volume from these models matches the corresponding MRI-measured volume at end-diastole and end-systole. Diastolic filling was simulated by loading the LV endocardial surface with a prescribed end-diastolic pressure. Systolic contraction was simulated by concurrently loading the endocardial surface with a prescribed end-systolic pressure and adding active contraction in the myofiber direction. Regional myofiber stress at end-diastole and end-systole was computed from the deformed LV based on the stress-strain relationship. PMID:23608998

Accessory atrioventricular pathways refractory to catheter ablation: role of percutaneous epicardial approach.

PubMed

Scanavacca, Maurício Ibrahim; Sternick, Eduardo Back; Pisani, Cristiano; Lara, Sissy; Hardy, Carina; d'Ávila, André; Correa, Frederico Soares; Darrieux, Francisco; Hachul, Denise; Marcial, Miguel Barbero; Sosa, Eduardo A

2015-02-01

Epicardial mapping and ablation of accessory pathways through a subxiphoid approach can be an alternative when endocardial or epicardial transvenous mapping has failed. We reviewed acute and long-term follow-up of 21 patients (14 males) referred for percutaneous epicardial accessory pathway ablation. There was a median of 2 previous failed procedures. All patients were highly symptomatic, 8 had atrial fibrillation (3 with cardiac arrest) and 13 had frequent symptomatic episodes of atrioventricular reentrant tachycardia. Six patients (28.5%) had a successful epicardial ablation. Five patients (23.8%) underwent a successful repeated endocardial mapping, and ablation after epicardial mapping yielded no early activation site. Epicardial mapping was helpful in guiding endocardial ablation in 2 patients (9.5%), showing that the earliest activation was simultaneous at the epicardium and endocardium. Four patients (19%) underwent successful open-chest surgery after failing epicardial/endocardial ablation. Two patients (9.5%) remained controlled under antiarrhythmic drugs after unsuccessful endocardial/epicardial ablation. Two patients had a coronary sinus diverticulum and one a right atrium to right ventricle diverticulum. Three patients acquired postablation coronary sinus stenosis. There was no major complication related to pericardial access. Percutaneous epicardial approach is an alternative when conventional endocardial or transvenous epicardial ablation fails in the elimination of the accessory pathway. A new attempt by endocardial approach was successful in a significant number of patients. Open-chest surgery may be required in symptomatic cases refractory to endocardial-epicardial approach. © 2014 American Heart Association, Inc.

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

PubMed

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

2018-04-01

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

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

PubMed

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

2018-06-01

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

Tissue Motion and Assembly During Early Cardiovascular Morphogenesis

NASA Astrophysics Data System (ADS)

Rongish, Brenda

2010-03-01

Conventional dogma in the field of cardiovascular developmental biology suggests that cardiac precursor cells migrate to the embryonic midline to form a tubular heart. These progenitors are believed to move relative to their extracellular matrix (ECM); responding to stimulatory and inhibitory cues in their environment. The tubular heart that is formed by 30 hours post fertilization is comprised of two concentric layers: the muscular myocardium and the endothelial-like endocardium, which are separated by a thick layer of ECM believed to be secreted predominantly by the myocardial cells. Here we describe the origin and motility of fluorescently tagged endocardial precursors in transgenic (Tie1-YFP) quail embryos (R. Lansford, Caltech) using epifluorescence time-lapse imaging. To visualize the environment of migrating endocardial progenitors, we labeled two ECM components, fibronectin and fibrillin-2, via in vivo microinjection of fluorochrome-conjugated monoclonal antibodies. Dynamic imaging was performed at stages encompassing tubular heart assembly and early looping. We established the motion of endocardial precursor cells and presumptive cardiac ECM fibrils using both object tracking and particle image velocimetry (image cross correlation). We determined the relative importance of directed cell autonomous motility versus passive tissue movements in endocardial morphogenesis. The data show presumptive endocardial cells and cardiac ECM fibrils are swept passively into the anterior and posterior poles of the elongating tubular heart. These quantitative data indicate the contribution of cell autonomous motility displayed by endocardial precursors is limited. Thus, tissue motion drives most of the cell displacements during endocardial morphogenesis.

Factors affecting basket catheter detection of real and phantom rotors in the atria: A computational study.

PubMed

Martinez-Mateu, Laura; Romero, Lucia; Ferrer-Albero, Ana; Sebastian, Rafael; Rodríguez Matas, José F; Jalife, José; Berenfeld, Omer; Saiz, Javier

2018-03-01

Anatomically based procedures to ablate atrial fibrillation (AF) are often successful in terminating paroxysmal AF. However, the ability to terminate persistent AF remains disappointing. New mechanistic approaches use multiple-electrode basket catheter mapping to localize and target AF drivers in the form of rotors but significant concerns remain about their accuracy. We aimed to evaluate how electrode-endocardium distance, far-field sources and inter-electrode distance affect the accuracy of localizing rotors. Sustained rotor activation of the atria was simulated numerically and mapped using a virtual basket catheter with varying electrode densities placed at different positions within the atrial cavity. Unipolar electrograms were calculated on the entire endocardial surface and at each of the electrodes. Rotors were tracked on the interpolated basket phase maps and compared with the respective atrial voltage and endocardial phase maps, which served as references. Rotor detection by the basket maps varied between 35-94% of the simulation time, depending on the basket's position and the electrode-to-endocardial wall distance. However, two different types of phantom rotors appeared also on the basket maps. The first type was due to the far-field sources and the second type was due to interpolation between the electrodes; increasing electrode density decreased the incidence of the second but not the first type of phantom rotors. In the simulations study, basket catheter-based phase mapping detected rotors even when the basket was not in full contact with the endocardial wall, but always generated a number of phantom rotors in the presence of only a single real rotor, which would be the desired ablation target. Phantom rotors may mislead and contribute to failure in AF ablation procedures.

Factors affecting basket catheter detection of real and phantom rotors in the atria: A computational study

PubMed Central

Romero, Lucia; Rodríguez Matas, José F.; Berenfeld, Omer; Saiz, Javier

2018-01-01

Anatomically based procedures to ablate atrial fibrillation (AF) are often successful in terminating paroxysmal AF. However, the ability to terminate persistent AF remains disappointing. New mechanistic approaches use multiple-electrode basket catheter mapping to localize and target AF drivers in the form of rotors but significant concerns remain about their accuracy. We aimed to evaluate how electrode-endocardium distance, far-field sources and inter-electrode distance affect the accuracy of localizing rotors. Sustained rotor activation of the atria was simulated numerically and mapped using a virtual basket catheter with varying electrode densities placed at different positions within the atrial cavity. Unipolar electrograms were calculated on the entire endocardial surface and at each of the electrodes. Rotors were tracked on the interpolated basket phase maps and compared with the respective atrial voltage and endocardial phase maps, which served as references. Rotor detection by the basket maps varied between 35–94% of the simulation time, depending on the basket’s position and the electrode-to-endocardial wall distance. However, two different types of phantom rotors appeared also on the basket maps. The first type was due to the far-field sources and the second type was due to interpolation between the electrodes; increasing electrode density decreased the incidence of the second but not the first type of phantom rotors. In the simulations study, basket catheter-based phase mapping detected rotors even when the basket was not in full contact with the endocardial wall, but always generated a number of phantom rotors in the presence of only a single real rotor, which would be the desired ablation target. Phantom rotors may mislead and contribute to failure in AF ablation procedures. PMID:29505583

On estimating intraventricular hemodynamic forces from endocardial dynamics: A comparative study with 4D flow MRI.

PubMed

Pedrizzetti, Gianni; Arvidsson, Per M; Töger, Johannes; Borgquist, Rasmus; Domenichini, Federico; Arheden, Håkan; Heiberg, Einar

2017-07-26

Intraventricular pressure gradients or hemodynamic forces, which are their global measure integrated over the left ventricular volume, have a fundamental importance in ventricular function. They may help revealing a sub-optimal cardiac function that is not evident in terms of tissue motion, which is naturally heterogeneous and variable, and can influence cardiac adaptation. However, hemodynamic forces are not utilized in clinical cardiology due to the unavailability of simple non-invasive measurement tools. Hemodynamic forces depend on the intraventricular flow; nevertheless, most of them are imputable to the dynamics of the endocardial flow boundary and to the exchange of momentum across the mitral and aortic orifices. In this study, we introduce a simplified model based on first principles of fluid dynamics that allows estimating hemodynamic forces without knowing the velocity field inside the LV. The model is validated with 3D phase-contrast MRI (known as 4D flow MRI) in 15 subjects, (5 healthy and 10 patients) using the endocardial surface reconstructed from the three standard long-axis projections. Results demonstrate that the model provides consistent estimates for the base-apex component (mean correlation coefficient r=0.77 for instantaneous values and r=0.88 for root mean square) and good estimates of the inferolateral-anteroseptal component (r=0.50 and 0.84, respectively). The present method represents a potential integration to the existing ones quantifying endocardial deformation in MRI and echocardiography to add a physics-based estimation of the corresponding hemodynamic forces. These could help the clinician to early detect sub-clinical diseases and differentiate between different cardiac dysfunctional states. Copyright © 2017 Elsevier Ltd. All rights reserved.

Successful Nd:Yag Laser Photocoagulation Of Arrhythmogenic Myocardium: Potential Limitations Of Current Optical Delivery Systems.

NASA Astrophysics Data System (ADS)

Svenson, Robert H.; Marroum, Marie-Claire; Frank, Frank; Selle, Jay G.; Gallagher, John J.; Bou-Saba, George; Seifert, Kathleen T.; Linder, Kathy; Tatsis, George P.

1987-04-01

Canine myocardial lesions of predictable dimensions can be achieved with Nd:YAG laser photocoagulation. These lesions are well demarcated from surrounding normal tissue and heal with homogeneous scar formation. Intraoperative Nd:YAG laser photocoagulation successfully ablated 52 of 55 ventricular tachycardias in 17 patients. Histologic examination of tissues from these arrhythmogenic areas showed differences from lesions produced on canine epicardium. Lesions from the human cases were less predictable and not well circumscribed. These differences are felt to be due to optical inhomogeneities present in diseased, scarred human myocardium, geometric irregularities of the endocardial surface, anatomical constraints on tissue-fiber distance, and the angle of incidence of the beam with the tissue. Modifications of current delivery systems may overcome some of these limitations. Ablation of ventricular tachycardia arising deeper than 4.0 to 6.0 mm. from the irradiated surface may require interstitial probes coupled to the fiberoptic.

The mechanism of endocardial lead-induced tricuspid regurgitation.

PubMed

Khoshbin, Espeed; Abdelbar, Abdelrahman; Allen, Stuart; Hasan, Ragheb

2013-04-09

Using this case report we attempt to define the mechanism of endocardial lead-induced tricuspid regurgitation (TR) in particular the direct effect of endocardial pacing leads on the competence of the tricuspid valve. We recommend a high index of suspicion and an early diagnostic strategy in order to reduce long-term morbidity which is associated with this condition and the need for a potentially avoidable surgery.

The mechanism of endocardial lead-induced tricuspid regurgitation

PubMed Central

Khoshbin, Espeed; Abdelbar, Abdelrahman; Allen, Stuart; Hasan, Ragheb

2013-01-01

Using this case report we attempt to define the mechanism of endocardial lead-induced tricuspid regurgitation (TR) in particular the direct effect of endocardial pacing leads on the competence of the tricuspid valve. We recommend a high index of suspicion and an early diagnostic strategy in order to reduce long-term morbidity which is associated with this condition and the need for a potentially avoidable surgery. PMID:23576646

A critical role for the EphA3 receptor tyrosine kinase in heart development.

PubMed

Stephen, Lesley J; Fawkes, Amy L; Verhoeve, Adam; Lemke, Greg; Brown, Arthur

2007-02-01

Eph proteins are receptor tyrosine kinases that control changes in cell shape and migration during development. We now describe a critical role for EphA3 receptor signaling in heart development as revealed by the phenotype of EphA3 null mice. During heart development mesenchymal outgrowths, the atrioventricular endocardial cushions, form in the atrioventricular canal. This morphogenetic event requires endocardial cushion cells to undergo an epithelial to mesenchymal transformation (EMT), and results in the formation of the atrioventricular valves and membranous portions of the atrial and ventricular septa. We show that EphA3 knockouts have significant defects in the development of their atrial septa and atrioventricular endocardial cushions, and that these cardiac abnormalities lead to the death of approximately 75% of homozygous EphA3(-/-) mutants. We demonstrate that EphA3 and its ligand, ephrin-A1, are expressed in adjacent cells in the developing endocardial cushions. We further demonstrate that EphA3(-/-) atrioventricular endocardial cushions are hypoplastic compared to wildtype and that EphA3(-/-) endocardial cushion explants give rise to fewer migrating mesenchymal cells than wildtype explants. Thus our results indicate that EphA3 plays a crucial role in the development and morphogenesis of the cells that give rise to the atrioventricular valves and septa.

Ethical considerations of transparency, informed consent, and nudging in a patient with paediatric aortic stenosis and symptomatic left ventricular endocardial fibroelastosis.

PubMed

Mavroudis, Constantine D; Cook, Thomas; Jacobs, Jeffrey P; Mavroudis, Constantine

2016-12-01

A 9-year-old boy who was born with bicuspid aortic stenosis underwent two unsuccessful aortic valvuloplasty interventions, and by 2 years of age he developed restrictive cardiomyopathy caused by left ventricular endocardial fibroelastosis and diastolic dysfunction. The attending cardiologist referred the patient to a high-volume, high-profile congenital cardiac surgical programme 1000 miles away that has a team with considerable experience with left ventricular endocardial fibroelastosis resection and a reputation of achieving good results. Owing to problems with insurance coverage, the parents sought other options for the care of their child in their home state. Dr George Miller is a well-respected local congenital and paediatric cardiac surgeon with considerable experience with the Ross operation as well as with right ventricular endocardial fibroelastosis resection. When talking with Dr Miller, he implied that there is little difference between right ventricular endocardial fibroelastosis and left ventricular endocardial fibroelastosis resection, and stated that he would perform the operation with low mortality based on his overall experience. Dr Miller stated that the local institution could provide an equivalent surgical procedure with comparable outcomes, without the patient and family having to travel out of state. A fundamental dilemma that often arises in clinical surgical practice concerns the conduct of assessing and performing new procedures, especially in rare cases, for which the collective global experience is scant. Although Dr Miller has performed right ventricular endocardial fibroelastosis resection, this procedure differs from left ventricular endocardial fibroelastosis resection, and he cannot be sure that he will indeed be able to perform the procedure better than the high-volume surgeon. This ethical situation is best understood in terms of the principles of respect for patient autonomy, beneficence, non-maleficence, and justice. The tension between the imperatives of beneficence and the obligation to respect the autonomy of the patient by acting only with the patient's best interest in mind is discussed.

Comparison of magnetic resonance imaging with cross-sectional echocardiography in the assessment of left ventricular mass in children without heart disease and in aortic isthmic coarctation.

PubMed

Vogel, M; Stern, H; Bauer, R; Bühlmeyer, K

1992-04-01

Although left ventricular (LV) mass may be important to judge effects of left-sided cardiac obstruction or hypertension, reproducible noninvasively determined normal data in the pediatric age group are scarce. To validate cross-sectional echocardiographic LV mass determination, our data were compared with LV mass assessed by magnetic resonance imaging (MRI). MRI was considered to be a good reference method because there is usually no problem in defining endo- and epicardial borders with MRI. LV mass was assessed in 14 children aged 5.3 years (10 days to 14.7 years) with a mean body surface area of 0.78 m2 (range 0.25 to 1.61). With cross-sectional echocardiography the epicardial and endocardial volumes were calculated using a Simpsons rule algorithm in the apical 2- and 4-chamber view. The difference between epi- and endocardial volumes was multiplied by 1.05 to yield the mass. Mass was assessed with MRI using a multislice technique; the area of each myocardial slice was calculated and multiplied with the slice thickness, and the resultant slice volumes were added to obtain the myocardial volume. On cross-sectional echocardiography, the mass was 55 g (range 12 to 126) or 64 g/m2 (range 46 to 79); on MRI it was 60 g (range 33 to 87) or 69 g/m2 (range 46 to 89). Regression analysis yielded an r value of 0.98 with a standard error of the estimate of 5.7 g or a 10% difference. In older children, LV mass determined by MRI was bigger than the one derived by echocardiography. It is concluded that cross-sectional echocardiography can reliably assess LV myocardial mass in pediatric patients.

Unipolar atrial electrogram morphology from an epicardial and endocardial perspective.

PubMed

van der Does, Lisette J M E; Knops, Paul; Teuwen, Christophe P; Serban, Corina; Starreveld, Roeliene; Lanters, Eva A H; Mouws, Elisabeth M J P; Kik, Charles; Bogers, Ad J J C; de Groot, Natasja M S

2018-02-22

Endo-epicardial asynchrony (EEA) and the interplay between the endocardial and epicardial layers could be important in the pathophysiology of atrial arrhythmias. The morphologic differences between epicardial and endocardial atrial electrograms have not yet been described, and electrogram morphology may hold information about the presence of EEA. The purpose of this study was to directly compare epicardial to endocardial unipolar electrogram morphology during sinus rhythm (SR) and to evaluate whether EEA contributes to electrogram fractionation by correlating fractionation to spatial activation patterns. In 26 patients undergoing cardiac surgery, unipolar electrograms were simultaneously recorded from the epicardium and endocardium at the inferior, middle, and superior right atrial (RA) free wall during SR. Potentials were analyzed for epi-endocardial differences in local activation time, voltage, RS ratio, and fractionation. The surrounding and opposite electrograms of fractionated deflections were evaluated for corresponding local activation times in order to determine whether fractionation originated from EEA. The superior RA was predisposed to delayed activation, EEA, and fractionation. Both epicardial and endocardial electrograms demonstrated an S-predominance. Fractionation was mostly similar between the 2 sides; however, incidentally deflections up to 4 mV on 1 side could be absent on the other side. Remote activation was responsible for most fractionated deflections (95%) in SR, of which 4% could be attributed to EEA. Local epi-endocardial differences in electrogram fractionation occur occasionally during SR but will likely increase during arrhythmias due to increasing EEA and (functional) conduction disorders. Electrogram fractionation can originate from EEA, and this study demonstrated that unipolar electrogram fractionation can potentially identify EEA. Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

An abdominal active can defibrillator may facilitate a successful generator change when a lead failure is present.

PubMed

Solomon, A J; Moubarak, J B; Drood, J M; Tracy, C M; Karasik, P E

1999-10-01

Defibrillator generator changes are frequently performed on patients with an implantable cardioverter defibrillator in an abdominal pocket. These patients usually have epicardial patches or older endocardial lead systems. At the time of a defibrillator generator change defibrillation may be unsuccessful as a result of lead failure. We tested the hypothesis that an active can defibrillator implanted in the abdominal pocket could replace a non-functioning endocardial lead or epicardial patch. An abdominal defibrillator generator change was performed in 10 patients, (mean age = 67 +/- 13 years, nine men). Initially, a defibrillation threshold (DFT) was obtained using a passive defibrillator and the chronic endocardial or epicardial lead system. DFTs were then performed using an active can emulator and one chronic lead to simulate endocardial or epicardial lead failure. We tested 30 lead configurations (nine endocardial and 21 epicardial). Although a DFT of 7.3 +/- 4.2 joules was obtained with the intact chronic lead system, the active can emulator and one endocardial or epicardial lead still yielded an acceptable DFT of 19.9 +/- 6.1 joules. In addition, a successful implant (DFT < or = 24 joules) could have been accomplished in 28 of 30 (93%) lead configurations. An active can defibrillator in an abdominal pocket may allow for a successful generator change in patients with defibrillator lead malfunction. This would be simpler than abandoning the abdominal implant and moving to a new pectoral device and lead or tunnelling a new endocardial electrode. However, loss of defibrillation capability with a particular complex lead may be a warning of impending loss of other functions (eg. sensing and/or pacing).

Linear lesions in heart tissue using diffused laser radiation

NASA Astrophysics Data System (ADS)

Fried, Nathaniel M.; Lardo, Albert C.; Berger, Ronald D.; Calkins, Hugh; Halperin, Henry R.

2000-05-01

Transmural, continuous, and linear lesions may be necessary for successful catheter ablation of cardiac arrythmias such as atrial fibrillation. Laser ablation was studied as an alternative to radiofrequency ablation, which is noted to produce superficial and discontinuous lesions as well as tissue charring and vaporization. Samples of canine myocardium were placed in a saline bath and irradiated with an 1.06- micrometer Nd:YAG laser operated in either pulsed or continuous mode. For pulsed mode, the laser pulse duration was 10 s with 10 s cooling between pulses. Laser radiation was delivered radially through diffusing optical fiber tips oriented parallel to the endocardial surface. In CW mode, transmural (6-mm-deep), linear (16-mm-long), and continuous lesions were produced using a laser power of 30 W and an irradiation time of 180 s. Peak tissue temperatures measured 51 plus or minus 1 degree Celsius at the endocardial surface, 61 plus or minus 6 degrees Celsius in the mid-myocardium, and 55 plus or minus 6 degree Celsius at the epicardial surface. There was no evidence of tissue charring or vaporization. Pulsed laser irradiation produced comparable lesion depths to CW irradiation with more uniform heating of the subsurface myocardium, but at the expense of longer operation times. Further in vivo study of laser ablation is warranted for possible clinical applications.

The Pathogenesis of Atrial and Atrioventricular Septal Defects with Special Emphasis on the Role of the Dorsal Mesenchymal Protrusion

PubMed Central

Briggs, Laura E.; Kakarla, Jayant; Wessels, Andy

2012-01-01

Partitioning of the four-chambered heart requires the proper formation, interaction and fusion of several mesenchymal tissues derived from different precursor populations that together form the atrioventricular mesenchymal complex. This includes the major endocardial cushions and the mesenchymal cap of the septum primum, which are of endocardial origin, and the dorsal mesenchymal protrusion (DMP), which is derived from the Second Heart Field. Failure of these structures to develop and/or fully mature results in atrial septal defects (ASDs) and atrioventricular septal defects (AVSD). AVSDs are congenital malformations in which the atria are permitted to communicate due to defective septation between the inferior margin of the septum primum and the atrial surface of the common atrioventricular valve. The clinical presentation of AVSDs is variable and depends on both the size and/or type of defect; less severe defects may be asymptomatic while the most severe defect, if untreated, results in infantile heart failure. For many years, maldevelopment of the endocardial cushions was thought to be the sole etiology of AVSDs. More recent work, however, has demonstrated that perturbation of DMP development also results in AVSD. Here, we discuss in detail the formation of the DMP, its contribution to cardiac septation and describe the morphological features as well as potential etiologies of ASDs and AVSDs. PMID:22709652

Acquired tricuspid valve stenosis associated with two ventricular endocardial pacing leads in a dog.

PubMed

Tompkins, Emily; Dulake, Michelle I; Ghaffari, Shadie; Nakamura, Reid K

2015-01-01

Acquired tricuspid valve stenosis (TVS) is a rare complication of endocardial pacing lead implantation in humans that has only been described once previously in the veterinary literature in a dog with excessive lead redundancy. A 12 yr old terrier presented with right-sided congestive heart failure 6 mo after implantation of a second ventricular endocardial pacing lead. The second lead was placed due to malfunction of the first lead, which demonstrated abnormally low impedance. Transthoracic echocardiography identified hyperechoic tissue associated with the pacing leads as they crossed the tricuspid valve annulus as well as a stenotic tricuspid inflow pattern via spectral Doppler interrogation. Medical management was ultimately unsuccessful and the dog was euthanized 6 wk after TVS was diagnosed. The authors report the first canine case of acquired TVS associated with two ventricular endocardial pacing leads.

A mathematical model of action potential heterogeneity in adult rat left ventricular myocytes.

PubMed Central

Pandit, S V; Clark, R B; Giles, W R; Demir, S S

2001-01-01

Mathematical models were developed to reconstruct the action potentials (AP) recorded in epicardial and endocardial myocytes isolated from the adult rat left ventricle. The main goal was to obtain additional insight into the ionic mechanisms responsible for the transmural AP heterogeneity. The simulation results support the hypothesis that the smaller density and the slower reactivation kinetics of the Ca(2+)-independent transient outward K(+) current (I(t)) in the endocardial myocytes can account for the longer action potential duration (APD), and more prominent rate dependence in that cell type. The larger density of the Na(+) current (I(Na)) in the endocardial myocytes results in a faster upstroke (dV/dt(max)). This, in addition to the smaller magnitude of I(t), is responsible for the larger peak overshoot of the simulated endocardial AP. The prolonged APD in the endocardial cell also leads to an enhanced amplitude of the sustained K(+) current (I(ss)), and a larger influx of Ca(2+) ions via the L-type Ca(2+) current (I(CaL)). The latter results in an increased sarcoplasmic reticulum (SR) load, which is mainly responsible for the higher peak systolic value of the Ca(2+) transient [Ca(2+)](i), and the resultant increase in the Na(+)-Ca(2+) exchanger (I(NaCa)) activity, associated with the simulated endocardial AP. In combination, these calculations provide novel, quantitative insights into the repolarization process and its naturally occurring transmural variations in the rat left ventricle. PMID:11720973

Loss of muscleblind-like 1 promotes invasive mesenchyme formation in endocardial cushions by stimulating autocrine TGFβ3

PubMed Central

2012-01-01

Background Valvulogenesis and septation in the developing heart depend on the formation and remodeling of endocardial cushions in the atrioventricular canal (AVC) and outflow tract (OFT). These cushions are invaded by a subpopulation of endocardial cells that undergo an epithelial-mesenchymal transition in response to paracrine and autocrine transforming growth factor β (TGFβ) signals. We previously demonstrated that the RNA binding protein muscleblind-like 1 (MBNL1) is expressed specifically in the cushion endocardium, and knockdown of MBNL1 in stage 14 embryonic chicken AVC explants enhances TGFβ-dependent endocardial cell invasion. Results In this study, we demonstrate that the effect of MBNL1 knockdown on invasion remains dependent on TGFβ3 after it is no longer required to induce basal levels of invasion. TGFβ3, but not TGFβ2, levels are elevated in medium conditioned by MBNL1-depleted AVC explants. TGFβ3 is elevated even when the myocardium is removed, indicating that MBNL1 modulates autocrine TGFβ3 production in the endocardium. More TGFβ3-positive cells are observed in the endocardial monolayer following MBNL1 knockdown. Addition of exogenous TGFβ3 to AVC explants recapitulates the effects of MBNL1 knockdown. Time course experiments demonstrate that knockdown of MBNL1 induces precocious TGFβ3 secretion, and early exposure to excess TGFβ3 induces precocious invasion. MBNL1 expression precedes TGFβ3 in the AVC endocardium, consistent with a role in preventing precocious autocrine TGFβ3 signaling. The stimulatory effects of MBNL1 knockdown on invasion are lost in stage 16 AVC explants. Knockdown of MBNL1 in OFT explants similarly enhances cell invasion, but not activation. TGFβ is necessary and sufficient to mediate this effect. Conclusions Taken together, these data support a model in which MBNL1 negatively regulates cell invasion in the endocardial cushions by restricting the magnitude and timing of endocardial-derived TGFβ3 production. PMID:22866814

Spatial resolution of pace mapping of idiopathic ventricular tachycardia/ectopy originating in the right ventricular outflow tract.

PubMed

Bogun, Frank; Taj, Majid; Ting, Michael; Kim, Hyungjin Myra; Reich, Stephen; Good, Eric; Jongnarangsin, Krit; Chugh, Aman; Pelosi, Frank; Oral, Hakan; Morady, Fred

2008-03-01

Pace mapping has been used to identify the site of origin of focal ventricular arrhythmias. The spatial resolution of pace mapping has not been adequately quantified using currently available three-dimensional mapping systems. The purpose of this study was to determine the spatial resolution of pace mapping in patients with idiopathic ventricular tachycardia or premature ventricular contractions originating in the right ventricular outflow tract. In 16 patients with idiopathic ventricular tachycardia/ectopy from the right ventricular outflow tract, comparisons and classifications of pace maps were performed by two observers (good pace map: match >10/12 leads; inadequate pace map: match < or =10/12 leads) and a customized MATLAB 6.0 program (assessing correlation coefficient and normalized root mean square of the difference (nRMSd) between test and template signals). With an electroanatomic mapping system, the correlation coefficient of each pace map was correlated with the distance between the pacing site and the effective ablation site. The endocardial area within the 10-ms activation isochrone was measured. The ablation procedure was effective in all patients. Sites with good pace maps had a higher correlation coefficient and lower nRMSd than sites with inadequate pace maps (correlation coefficient: 0.96 +/- 0.03 vs 0.76 +/- 0.18, P <.0001; nRMSd: 0.41 +/- 0.16 vs 0.89 +/- 0.39, P <.0001). Using receiver operating characteristic curves, appropriate cutoff values were >0.94 for correlation coefficient (sensitivity 81%, specificity 89%) and < or =0.54 for nRMSd (sensitivity 76%, specificity 80%). Good pace maps were located a mean of 7.3 +/- 5.0 mm from the effective ablation site and had a mean activation time of -24 +/- 7 ms. However, in 3 (18%) of 16 patients, the best pace map was inadequate at the effective ablation site, with an endocardial activation time at these sites of -25 +/- 12 ms. Pace maps with correlation coefficient > or =0.94 were confined to an area of 1.8 +/- 0.6 cm2. The 10-ms isochrone measured 1.2 +/- 0.7 cm2. The spatial resolution of a good pace map for targeting ventricular tachycardia/ectopy is 1.8 cm2 in the right ventricular outflow tract and therefore is inferior to the spatial resolution of activation mapping as assessed by isochronal activation. In approximately 20% of patients, pace mapping is unreliable in identifying the site of origin, possibly due a deeper site of origin and preferential conduction via fibers connecting the focus to the endocardial surface.

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

PubMed

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

1987-01-01

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

Ultrastructure of myocardial widened Z bands and endocardial cells in two teleostean species.

PubMed

Leknes, I L

1981-01-01

Widened myocardial Z bands and endocardial cells are described in two teleostean species Cichlasoma meeki and Corydoras aeneus. Widened Z bands containing mainly amorphous and electron-dense material were seen in a number of myocardial cells. Further, similar material may occur in large amounts beneath the sarcolemma and at intercellular junctions. Occasionally, we observed continuity between the latter material and that in expanded Z bands. In C. meeki the ventricular endocardial layer consists of two structurally different cell types, whereas in C. aeneus only one cell type was seen. The functional aspects of widened Z bands are discussed.

Spiral-wave dynamics in a mathematical model of human ventricular tissue with myocytes and Purkinje fibers.

PubMed

Nayak, Alok Ranjan; Panfilov, A V; Pandit, Rahul

2017-02-01

We present systematic numerical studies of the possible effects of the coupling of human endocardial and Purkinje cells at cellular and two-dimensional tissue levels. We find that the autorhythmic-activity frequency of the Purkinje cell in a composite decreases with an increase in the coupling strength; this can even eliminate the autorhythmicity. We observe a delay between the beginning of the action potentials of endocardial and Purkinje cells in a composite; such a delay increases as we decrease the diffusive coupling, and eventually a failure of transmission occurs. An increase in the diffusive coupling decreases the slope of the action-potential-duration-restitution curve of an endocardial cell in a composite. By using a minimal model for the Purkinje network, in which we have a two-dimensional, bilayer tissue, with a layer of Purkinje cells on top of a layer of endocardial cells, we can stabilize spiral-wave turbulence; however, for a sparse distribution of Purkinje-ventricular junctions, at which these two layers are coupled, we can also obtain additional focal activity and many complex transient regimes. We also present additional effects resulting from the coupling of Purkinje and endocardial layers and discuss the relation of our results to the studies performed in anatomically accurate models of the Purkinje network.

A Hybrid Method for Endocardial Contour Extraction of Right Ventricle in 4-Slices from 3D Echocardiography Dataset.

PubMed

Dawood, Faten A; Rahmat, Rahmita W; Kadiman, Suhaini B; Abdullah, Lili N; Zamrin, Mohd D

2014-01-01

This paper presents a hybrid method to extract endocardial contour of the right ventricular (RV) in 4-slices from 3D echocardiography dataset. The overall framework comprises four processing phases. In Phase I, the region of interest (ROI) is identified by estimating the cavity boundary. Speckle noise reduction and contrast enhancement were implemented in Phase II as preprocessing tasks. In Phase III, the RV cavity region was segmented by generating intensity threshold which was used for once for all frames. Finally, Phase IV is proposed to extract the RV endocardial contour in a complete cardiac cycle using a combination of shape-based contour detection and improved radial search algorithm. The proposed method was applied to 16 datasets of 3D echocardiography encompassing the RV in long-axis view. The accuracy of experimental results obtained by the proposed method was evaluated qualitatively and quantitatively. It has been done by comparing the segmentation results of RV cavity based on endocardial contour extraction with the ground truth. The comparative analysis results show that the proposed method performs efficiently in all datasets with overall performance of 95% and the root mean square distances (RMSD) measure in terms of mean ± SD was found to be 2.21 ± 0.35 mm for RV endocardial contours.

Complex cardiac defects after ethanol exposure during discrete cardiogenic events in zebrafish: Prevention with folic acid

PubMed Central

Sarmah, Swapnalee; Marrs, James A.

2014-01-01

BACKGROUND Fetal alcohol spectrum disorder (FASD) describes a range of birth defects including various congenital heart defects (CHDs). Mechanisms of FASD-associated CHDs are not understood. Whether alcohol interferes with a single critical event or with multiple events in heart formation is not known. RESULTS Our zebrafish embryo experiments showed that ethanol interrupts different cardiac regulatory networks and perturbed multiple steps of cardiogenesis (specification, myocardial migration, looping, chamber morphogenesis and endocardial cushion formation). Ethanol exposure during gastrulation until cardiac specification or during myocardial midline migration did not produce severe or persistent heart development defects. However, exposure comprising gastrulation until myocardial precursor midline fusion or during heart patterning stages produced aberrant heart looping and defective endocardial cushions. Continuous exposure during entire cardiogenesis produced complex cardiac defects leading to severely defective myocardium, endocardium, and endocardial cushions. Supplementation of retinoic acid with ethanol partially rescued early heart developmental defects, but the endocardial cushions did not form correctly. In contrast, supplementation of folic acid rescued normal heart development, including the endocardial cushions. CONCLUSIONS Our results indicate that ethanol exposure interrupted divergent cardiac morphogenesis events causing heart defects. Folic acid supplementation was effective in preventing a wide spectrum of ethanol-induced heart developmental defects. PMID:23832875

Spiral-wave dynamics in a mathematical model of human ventricular tissue with myocytes and Purkinje fibers

NASA Astrophysics Data System (ADS)

Nayak, Alok Ranjan; Panfilov, A. V.; Pandit, Rahul

2017-02-01

We present systematic numerical studies of the possible effects of the coupling of human endocardial and Purkinje cells at cellular and two-dimensional tissue levels. We find that the autorhythmic-activity frequency of the Purkinje cell in a composite decreases with an increase in the coupling strength; this can even eliminate the autorhythmicity. We observe a delay between the beginning of the action potentials of endocardial and Purkinje cells in a composite; such a delay increases as we decrease the diffusive coupling, and eventually a failure of transmission occurs. An increase in the diffusive coupling decreases the slope of the action-potential-duration-restitution curve of an endocardial cell in a composite. By using a minimal model for the Purkinje network, in which we have a two-dimensional, bilayer tissue, with a layer of Purkinje cells on top of a layer of endocardial cells, we can stabilize spiral-wave turbulence; however, for a sparse distribution of Purkinje-ventricular junctions, at which these two layers are coupled, we can also obtain additional focal activity and many complex transient regimes. We also present additional effects resulting from the coupling of Purkinje and endocardial layers and discuss the relation of our results to the studies performed in anatomically accurate models of the Purkinje network.

The Role of Transmural Repolarization Gradient in the Inversion of Cardiac Electric Field: Model Study of ECG in Hypothermia.

PubMed

Arteyeva, Natalia V; Azarov, Jan E

2017-01-01

The changes in ventricular repolarization gradients lead to significant alterations of the electrocardiographic body surface T waves up to the T wave inversion. However, the contribution of a specific gradient remains to be elucidated. The objective of the present investigation was to study the role of the transmural repolarization gradient in the inversion of the body surface T wave with a mathematical model of the hypothermia-induced changes of ventricular repolarization. By means of mathematical simulation, we set the hypothermic action potential duration (APD) distribution on the rabbit ventricular epicardium as it was previously experimentally documented. Then the parameters of the body surface potential distribution were tested with the introduction of different scenarios of the endocardial and epicardial APD behavior in hypothermia resulting in the unchanged, reversed or enlarged transmural repolarization gradient. The reversal of epicardial repolarization gradients (apicobasal, anterior-posterior and interventricular) caused the inversion of the T waves regardless of the direction of the transmural repolarization gradient. However, the most realistic body surface potentials were obtained when the endocardial APDs were not changed under hypothermia while the epicardial APDs prolonged. This produced the reversed and increased transmural repolarization gradient in absolute magnitude. The body surface potentials simulated under the unchanged transmural gradient were reduced in comparison to those simulated under the reversed transmural gradient. The simulations demonstrated that the transmural repolarization gradient did not play a crucial role in the cardiac electric field inversion under hypothermia, but its magnitude and direction contribute to the T wave amplitude. © 2016 Wiley Periodicals, Inc.

Left Ventricular Trabeculations Decrease the Wall Shear Stress and Increase the Intra-Ventricular Pressure Drop in CFD Simulations

PubMed Central

Sacco, Federica; Paun, Bruno; Lehmkuhl, Oriol; Iles, Tinen L.; Iaizzo, Paul A.; Houzeaux, Guillaume; Vázquez, Mariano; Butakoff, Constantine; Aguado-Sierra, Jazmin

2018-01-01

The aim of the present study is to characterize the hemodynamics of left ventricular (LV) geometries to examine the impact of trabeculae and papillary muscles (PMs) on blood flow using high performance computing (HPC). Five pairs of detailed and smoothed LV endocardium models were reconstructed from high-resolution magnetic resonance images (MRI) of ex-vivo human hearts. The detailed model of one LV pair is characterized only by the PMs and few big trabeculae, to represent state of art level of endocardial detail. The other four detailed models obtained include instead endocardial structures measuring ≥1 mm2 in cross-sectional area. The geometrical characterizations were done using computational fluid dynamics (CFD) simulations with rigid walls and both constant and transient flow inputs on the detailed and smoothed models for comparison. These simulations do not represent a clinical or physiological scenario, but a characterization of the interaction of endocardial structures with blood flow. Steady flow simulations were employed to quantify the pressure drop between the inlet and the outlet of the LVs and the wall shear stress (WSS). Coherent structures were analyzed using the Q-criterion for both constant and transient flow inputs. Our results show that trabeculae and PMs increase the intra-ventricular pressure drop, reduce the WSS and disrupt the dominant single vortex, usually present in the smoothed-endocardium models, generating secondary small vortices. Given that obtaining high resolution anatomical detail is challenging in-vivo, we propose that the effect of trabeculations can be incorporated into smoothed ventricular geometries by adding a porous layer along the LV endocardial wall. Results show that a porous layer of a thickness of 1.2·10−2 m with a porosity of 20 kg/m2 on the smoothed-endocardium ventricle models approximates the pressure drops, vorticities and WSS observed in the detailed models. PMID:29760665

Electrical latency predicts the optimal left ventricular endocardial pacing site: results from a multicentre international registry.

PubMed

Sieniewicz, Benjamin J; Behar, Jonathan M; Sohal, Manav; Gould, Justin; Claridge, Simon; Porter, Bradley; Niederer, Steve; Gamble, James H P; Betts, Tim R; Jais, Pierre; Derval, Nicolas; Spragg, David D; Steendijk, Paul; van Gelder, Berry M; Bracke, Frank A; Rinaldi, Christopher A

2018-04-23

The optimal site for biventricular endocardial (BIVENDO) pacing remains undefined. Acute haemodynamic response (AHR) is reproducible marker of left ventricular (LV) contractility, best expressed as the change in the maximum rate of LV pressure (LV-dp/dtmax), from a baseline state. We examined the relationship between factors known to impact LV contractility, whilst delivering BIVENDO pacing at a variety of LV endocardial (LVENDO) locations. We compiled a registry of acute LVENDO pacing studies from five international centres: Johns Hopkins-USA, Bordeaux-France, Eindhoven-The Netherlands, Oxford-United Kingdom, and Guys and St Thomas' NHS Foundation Trust, London-UK. In all, 104 patients incorporating 687 endocardial and 93 epicardial pacing locations were studied. Mean age was 66 ± 11 years, mean left ventricular ejection fraction 24.6 ± 7.7% and mean QRS duration of 163 ± 30 ms. In all, 50% were ischaemic [ischaemic cardiomyopathy (ICM)]. Scarred segments were associated with worse haemodynamics (dp/dtmax; 890 mmHg/s vs. 982 mmHg/s, P < 0.01). Delivering BiVENDO pacing in areas of electrical latency was associated with greater improvements in AHR (P < 0.01). Stimulating late activating tissue (LVLED >50%) achieved greater increases in AHR than non-late activating tissue (LVLED < 50%) (8.6 ± 9.6% vs. 16.1 ± 16.2%, P = 0.002). However, the LVENDO pacing location with the latest Q-LV, was associated with the optimal AHR in just 62% of cases. Identifying viable LVENDO tissue which displays late electrical activation is crucial to identifying the optimal BiVENDO pacing site. Stimulating late activating tissue (LVLED >50%) yields greater improvements in AHR however, the optimal location is frequently not the site of latest activation.

[Pathomorphologic and ultrastructural characteristics of endocardial Cysticercus cellulosae].

PubMed

Grozdev, L J; Kaftandziev, D; Roganovic, D; Colanceski, V

1980-01-01

A case is presented of a solitary endocardial cysticercus of cellulose discovered at a biopsy in the left auricula of the heart, got by a 36-year old patient at the operation who had a mitral and aortal defect caused by a reumatic endocarditis. The cisticercus is implanted on the surface of an intact endothelium and the fibroelastic structure of the superficial part of the endocardium is preserved. Inflammation of the endocardium and the myocardium is presented by a perivascular infiltrates eosinophile granulocytes, plasms cells and lymphocytes, suggesting an allergic nature of inflammation. In histological preparates stained by selective methods of fungus according to Gridley and Crocott on the wall of the membrane of the cyst polymorphal Yeast-like elements are discovered at a size of 2-12 mil. mic. which ultrastructurally show degenerative forms of membranous structures suspected as immature primitive proglotids. In this paper, the objective difficulties are pointed out at the microscopic diagnosis of the cisticercus in the pathological material.

Overlapping and differential localization of Bmp-2, Bmp-4, Msx-2 and apoptosis in the endocardial cushion and adjacent tissues of the developing mouse heart.

PubMed

Abdelwahid, E; Rice, D; Pelliniemi, L J; Jokinen, E

2001-07-01

The bone morphogenetic proteins BMP-2 and BMP-4 and the homeobox gene MSX-2 are required for normal development of many embryonic tissues. To elucidate their possible roles during the remodeling of the tubular heart into a fully septated four-chambered heart, we have localized the mRNA of Bmp-2, Bmp-4, Msx-2 and apoptotic cells in the developing mouse heart from embryonic day (E)11 to E17. mRNA was localized by in situ hybridization, and apoptotic cells by TUNEL (TDT-mediated dUTP-biotin nick end-labeling) as well as by transmission electron microscopy. By analyzing adjacent serial sections, we demonstrated that the expression of Msx-2 and Bmp-2 strikingly overlapped in the atrioventricular canal myocardium, in the atrioventricular junctional myocardium, and in the maturing myocardium of the atrioventricular valves. Bmp-4 was expressed in the outflow tract myocardium and in the endocardial cushion of the outflow tract ridges from E12 to E14. Msx-2 appeared in the mesenchyme of the atrioventricular endocardial cushion from E11 to E14, while Bmp-2 and Bmp-4 were detected between E11 and E14. Apoptotic cells were also detected in the mesenchyme of the endocardial cushion between E12 and E14. Our results suggest that BMP-2 and MSX-2 are tightly linked to the formation of the atrioventricular junction and valves and that BMP-4 is involved in the development of the outflow tract myocardium and of the endocardial cushion. In addition, BMP-2, BMP-4 and MSX-2 and apoptosis seem to be associated with differentiation of the endocardial cushion.

klf2a couples mechanotransduction and zebrafish valve morphogenesis through fibronectin synthesis

PubMed Central

Steed, Emily; Faggianelli, Nathalie; Roth, Stéphane; Ramspacher, Caroline; Concordet, Jean-Paul; Vermot, Julien

2016-01-01

The heartbeat and blood flow signal to endocardial cell progenitors through mechanosensitive proteins that modulate the genetic program controlling heart valve morphogenesis. To date, the mechanism by which mechanical forces coordinate tissue morphogenesis is poorly understood. Here we use high-resolution imaging to uncover the coordinated cell behaviours leading to heart valve formation. We find that heart valves originate from progenitors located in the ventricle and atrium that generate the valve leaflets through a coordinated set of endocardial tissue movements. Gene profiling analyses and live imaging reveal that this reorganization is dependent on extracellular matrix proteins, in particular on the expression of fibronectin1b. We show that blood flow and klf2a, a major endocardial flow-responsive gene, control these cell behaviours and fibronectin1b synthesis. Our results uncover a unique multicellular layering process leading to leaflet formation and demonstrate that endocardial mechanotransduction and valve morphogenesis are coupled via cellular rearrangements mediated by fibronectin synthesis. PMID:27221222

The role of surgery in the treatment of post-infarction ventricular tachycardia. A 5 year experience.

PubMed

Martinelli, L; Goggi, C; Graffigna, A; Salerno, J A; Chimienti, M; Klersy, C; Viganò, M

1987-01-01

The purpose of this report is to present a 5 year experience in electrophysiologically guided surgical treatment of post-infarction ventricular tachycardia (VT) in a consecutive series of 39 patients. In every case the arrhythmia was not responsive to pluripharmacological therapy. The diagnostic steps included preoperative endocardial, intraoperative epi- and endocardial mapping, automatically carried out when possible. Surgical techniques were: classic Guiraudon's encircling endocardial ventriculotomy (EEV), partial EEV, endocardial resection (ER), cryoablation or combined procedures. The hospital mortality was of 4 patients (10%). During the follow-up period (1-68 mo), 4 patients (11%) died of cardiac non-VT related causes. Among the survivors, 90% are in sinus rhythm. The authors consider electrophysiologically guided surgery a safe and reliable method for the treatment of post-infarction VT and suggest more extensive indications. They stress the importance of automatic mapping in pleomorphic and non-sustained VT, and the necessity of tailoring the surgical technique to the characteristics of each case.

Ventricular tachycardia in post-myocardial infarction patients. Results of surgical therapy.

PubMed

Viganò, M; Martinelli, L; Salerno, J A; Minzioni, G; Chimienti, M; Graffigna, A; Goggi, C; Klersy, C; Montemartini, C

1986-05-01

This report addresses the problems related to surgical treatment of post-infarction ventricular tachycardia (VT) and is based on a 5 year experience of 36 consecutive patients. In every case the arrhythmia was unresponsive to pharmacological therapy. All patients were operated on after the completion of a diagnostic protocol including preoperative endocardial, intra-operative epi-endocardial mapping, the latter performed automatically when possible. Surgical techniques were: classical Guiraudon's encircling endocardial ventriculotomy (EEV); partial EEV, endocardial resection (ER); cryoablation or a combination of these procedures. The in-hospital mortality (30 days) was 8.3% (3 patients). During the follow-up period (1-68 months), 3 patients (9%) died of cardiac but not VT related causes. Of the survivors, 92% are VT-free. We consider electrophysiologically guided surgery a safe and reliable method for the treatment of post-infarction VT and suggest its more extensive use. We stress the importance of automatic mapping in pleomorphic and non-sustained VT, and the necessity of tailoring the surgical technique to the characteristics of each case.

Qualitative and quantitative effects of harmonic echocardiographic imaging on endocardial edge definition and side-lobe artifacts

NASA Technical Reports Server (NTRS)

Rubin, D. N.; Yazbek, N.; Garcia, M. J.; Stewart, W. J.; Thomas, J. D.

2000-01-01

Harmonic imaging is a new ultrasonographic technique that is designed to improve image quality by exploiting the spontaneous generation of higher frequencies as ultrasound propagates through tissue. We studied 51 difficult-to-image patients with blinded side-by-side cineloop evaluation of endocardial border definition by harmonic versus fundamental imaging. In addition, quantitative intensities from cavity versus wall were compared for harmonic versus fundamental imaging. Harmonic imaging improved left ventricular endocardial border delineation over fundamental imaging (superior: harmonic = 71.1%, fundamental = 18.7%; similar: 10.2%; P <.001). Quantitative analysis of 100 wall/cavity combinations demonstrated brighter wall segments and more strikingly darker cavities during harmonic imaging (cavity intensity on a 0 to 255 scale: fundamental = 15.6 +/- 8.6; harmonic = 6.0 +/- 5.3; P <.0001), which led to enhanced contrast between the wall and cavity (1.89 versus 1.19, P <.0001). Harmonic imaging reduces side-lobe artifacts, resulting in a darker cavity and brighter walls, thereby improving image contrast and endocardial delineation.

A left ventricular epicardial to right ventricular endocardial dominant frequency gradient exists in human ventricular fibrillation.

PubMed

Torres, Jose Luis; Shah, Bindi K; Greenberg, Richard M; Deger, Florin Titus; Gerstenfeld, Edward P

2010-10-01

We hypothesized that in patients with left ventricular dysfunction undergoing implant of a biventricular ICD, the local dominant frequency during early induced ventricular fibrillation would be higher at an epicardial left ventricular position compared to an endocardial right ventricular position. Patients undergoing implant of a biventricular ICD were studied. During ventricular fibrillation induction, bipolar electrograms were recorded from leads at an epicardial left ventricular position and an endocardial right ventricular position. Overlapping 2-s fast Fourier transforms were obtained for 6 s of ventricular fibrillation. The dominant frequency and organizational index were compared. Thirty-four patients (20 men, age 64 ± 11 years) underwent 57 inductions of ventricular fibrillation. Eighteen patients had non-ischemic dilated cardiomyopathy and 16 had ischemic dilated cardiomyopathy. The dominant frequency was higher at a lateral epicardial left ventricular position than an apical endocardial right ventricular position in 18 patients with non-ischemic dilated cardiomyopathy (LV epicardial 5.34 ± 0.37 Hz, RV endocardial 5.09 ± 0.41 Hz, p < 0.001), but not in 16 patients with ischemic dilated cardiomyopathy (LV epicardial 4.99 ± 0.57 Hz, RV epicardial 4.87 ± 0.65 Hz, p = 0.094). In patients with non-ischemic dilated cardiomyopathy, there is a dominant frequency gradient during early ventricular fibrillation induced at ICD testing from the lateral left ventricular epicardium to the apical right ventricular endocardium.

Successful treatment of mitral valve endocarditis in a dog associated with 'Actinomyces canis-like' infection.

PubMed

Balakrishnan, N; Alexander, K; Keene, B; Kolluru, S; Fauls, M L; Rawdon, I; Breitschwerdt, E B

2016-09-01

Infective endocarditis, an inflammation of the endocardial surface due to invasion by an infectious agent, is more common in middle sized to large breed dogs. We herein report a case of mitral valve endocarditis in a 9-year-old male-castrated Weimaraner caused by an Actinomyces canis-like bacterium, not previously reported in association with infection in dogs. Copyright © 2016 Elsevier B.V. All rights reserved.

Parasitic meningoencephalitis in nurse sharks (Ginglymostoma cirratum).

PubMed

Credille, K M; Johnson, L K; Reimschuessel, R

1993-07-01

Based on microscopic examination of the brains of seven wild-caught nurse sharks (Ginglymostoma cirratum), we observed a severe meningoencephalitis associated with numerous parasitic granulomas. The parasites were larval nematodes with morphological characteristics of the Superfamily Dracunculoidea. Although meningeal larval aggregates were associated with chronic inflammation, additional parasitic nodules found on the endocardial surface and perimandibular region did not provoke an inflammatory response. Neither the route of infection nor life cycle were determined.

Increased Regurgitant Flow Causes Endocardial Cushion Defects in an Avian Embryonic Model of Congenital Heart Disease

PubMed Central

Ford, Stephanie M; McPheeters, Matthew T; Wang, Yves T; Ma, Pei; Gu, Shi; Strainic, James; Snyder, Christopher; Rollins, Andrew M; Watanabe, Michiko; Jenkins, Michael W

2017-01-01

Background The relationship between changes in endocardial cushion and resultant congenital heart diseases (CHD) has yet to be established. It has been shown that increased regurgitant flow early in embryonic heart development leads to endocardial cushion defects, but it remains unclear how abnormal endocardial cushions during the looping stages might affect the fully septated heart. The goal of this study was to reproducibly alter blood flow in vivo and then quantify the resultant effects on morphology of endocardial cushions in the looping heart and on CHDs in the septated heart. Methods Optical pacing was applied to create regurgitant flow in embryonic hearts, and optical coherence tomography (OCT) was utilized to quantify regurgitation and morphology. Embryonic quail hearts were optically paced at 3 Hz (180bpm, well above intrinsic rate 60–110bpm) at stage 13 of development (3–4 wks human) for 5 min. Pacing fatigued the heart and led to at least 1 hr of increased regurgitant flow. Resultant morphological changes were quantified with OCT imaging at stage 19 (cardiac looping – 4–5 wks human) or stage 35 (4 chambered heart – 8 wks human). Results All paced embryos imaged at stage 19 displayed structural changes in cardiac cushions. The amount of regurgitant flow immediately after pacing was inversely correlated with cardiac cushion size 24-hrs post pacing (p-value < 0.01). The embryos with the most regurgitant flow and smallest cushions after pacing had a decreased survival rate at 8 days (p<0.05), indicating that those most severe endocardial cushion defects were lethal. Of the embryos that survived to stage 35, 17/18 exhibited CHDs including valve defects, ventricular septal defects, hypoplastic ventricles, and common AV canal. Conclusion The data illustrate a strong inverse relationship in which regurgitant flow precedes abnormal and smaller cardiac cushions, resulting in the development of CHDs. PMID:28211263

Metal Ir coatings on endocardial electrode tips, obtained by MOCVD

NASA Astrophysics Data System (ADS)

Vikulova, Evgeniia S.; Kal'nyi, Danila B.; Shubin, Yury V.; Kokovkin, Vasily V.; Morozova, Natalya B.; Hassan, Aseel; Basova, Tamara V.

2017-12-01

The present work demonstrates the application of the Metal-Organic Chemical Vapor Deposition technique to fabricate metal iridium coatings onto the pole tips of endocardial electrodes. Using iridium (III) acetylacetonate as a volatile precursor, the target coatings were successfully applied to the working surface of cathodes and anodes of pacemaker electrodes in the flow type reactor in hydrogen atmosphere at deposition temperature of 550 °C. The coating samples were characterized by means of XRD, SEM, Raman- and XPS-spectroscopies. The formation of non-textured coatings with fractal-like morphology and 7-24 nm crystallite size has been realized. The electrochemical properties of the coatings were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The charge storage capacity values of the electrochemically activated samples were 17.0-115 mC cm-2 and 14.4-76.5 mC cm-2 for measurements carried out in 0.1 M sulfuric acid and in phosphate buffer saline solutions, respectively. A comparison of some characteristics of the samples obtained with commercially available cathode of pacemaker electrodes is also presented.

Quantitative Differentiation of LV Myocardium with and without Layer-Specific Fibrosis Using MRI in Hypertrophic Cardiomyopathy and Layer-Specific Strain TTE Analysis.

PubMed

Funabashi, Nobusada; Takaoka, Hiroyuki; Ozawa, Koya; Kamata, Tomoko; Uehara, Masae; Komuro, Issei; Kobayashi, Yoshio

2018-05-30

To achieve further risk stratification in hypertrophic cardiomyopathy (HCM) patients, we localized and quantified layer-specific LVM fibrosis on MRI in HCM patients using regional layer-specific peak longitudinal strain (PLS) and peak circumferential strain (PCS) in LV myocardium (LVM) on speckle tracking transthoracic echocardiography (TTE). A total of 18 HCM patients (14 males; 58 ± 17 years) underwent 1.5T-MRI and TTE. PLS and PCS in each layer of the LVM (endocardium, epicardium, and whole-layer myocardium) were calculated for 17 AHA-defined lesions. MRI assessment showed that fibrosis was classified as endocardial, epicardial, or whole-layer (= either or both of these). Regional PLS was smaller in fibrotic endocardial lesions than in non-fibrotic endocardial lesions (P = 0.004). To detect LV endocardial lesions with fibrosis, ROC curves of regional PLS revealed an area under the curve (AUC) of 0.609 and a best cut-off point of 13.5%, with sensitivity of 65.3% and specificity of 54.3%. Regional PLS was also smaller in fibrotic epicardial lesions than in non-fibrotic epicardial lesions (P < 0.001). To detect LV epicardial lesions with fibrosis, ROC curves of PLS revealed an AUC of 0.684 and a best cut-off point of 9.5%, with sensitivity of 73.5% and specificity of 55.5%. Using whole-layer myocardium analysis, PLS was smaller in fibrotic lesions than in non-fibrotic lesions (P < 0.001). To detect whole-layer LV lesions with fibrosis, ROC curves of regional PLS revealed an AUC of 0.674 and a best cut-off point of 12.5%, with sensitivity of 79.0% and specificity of 50.7%. There were no significant differences in PCS of LV myocardium (endocardium, epicardium, and whole-layer) between fibrotic and non-fibrotic lesions. Quantitative regional PLS but not PCS in LV endocardium, epicardium, and whole-layer myocardium provides useful non-invasive information for layer-specific localization of fibrosis in HCM patients.

In vivo validation of cardiac output assessment in non-standard 3D echocardiographic images

NASA Astrophysics Data System (ADS)

Nillesen, M. M.; Lopata, R. G. P.; de Boode, W. P.; Gerrits, I. H.; Huisman, H. J.; Thijssen, J. M.; Kapusta, L.; de Korte, C. L.

2009-04-01

Automatic segmentation of the endocardial surface in three-dimensional (3D) echocardiographic images is an important tool to assess left ventricular (LV) geometry and cardiac output (CO). The presence of speckle noise as well as the nonisotropic characteristics of the myocardium impose strong demands on the segmentation algorithm. In the analysis of normal heart geometries of standardized (apical) views, it is advantageous to incorporate a priori knowledge about the shape and appearance of the heart. In contrast, when analyzing abnormal heart geometries, for example in children with congenital malformations, this a priori knowledge about the shape and anatomy of the LV might induce erroneous segmentation results. This study describes a fully automated segmentation method for the analysis of non-standard echocardiographic images, without making strong assumptions on the shape and appearance of the heart. The method was validated in vivo in a piglet model. Real-time 3D echocardiographic image sequences of five piglets were acquired in radiofrequency (rf) format. These ECG-gated full volume images were acquired intra-operatively in a non-standard view. Cardiac blood flow was measured simultaneously by an ultrasound transit time flow probe positioned around the common pulmonary artery. Three-dimensional adaptive filtering using the characteristics of speckle was performed on the demodulated rf data to reduce the influence of speckle noise and to optimize the distinction between blood and myocardium. A gradient-based 3D deformable simplex mesh was then used to segment the endocardial surface. A gradient and a speed force were included as external forces of the model. To balance data fitting and mesh regularity, one fixed set of weighting parameters of internal, gradient and speed forces was used for all data sets. End-diastolic and end-systolic volumes were computed from the segmented endocardial surface. The cardiac output derived from this automatic segmentation was validated quantitatively by comparing it with the CO values measured from the volume flow in the pulmonary artery. Relative bias varied between 0 and -17%, where the nominal accuracy of the flow meter is in the order of 10%. Assuming the CO measurements from the flow probe as a gold standard, excellent correlation (r = 0.99) was observed with the CO estimates obtained from image segmentation.

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

PubMed

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

2014-11-01

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

Automatic left-atrial segmentation from cardiac 3D ultrasound: a dual-chamber model-based approach

NASA Astrophysics Data System (ADS)

Almeida, Nuno; Sarvari, Sebastian I.; Orderud, Fredrik; Gérard, Olivier; D'hooge, Jan; Samset, Eigil

2016-04-01

In this paper, we present an automatic solution for segmentation and quantification of the left atrium (LA) from 3D cardiac ultrasound. A model-based framework is applied, making use of (deformable) active surfaces to model the endocardial surfaces of cardiac chambers, allowing incorporation of a priori anatomical information in a simple fashion. A dual-chamber model (LA and left ventricle) is used to detect and track the atrio-ventricular (AV) plane, without any user input. Both chambers are represented by parametric surfaces and a Kalman filter is used to fit the model to the position of the endocardial walls detected in the image, providing accurate detection and tracking during the whole cardiac cycle. This framework was tested in 20 transthoracic cardiac ultrasound volumetric recordings of healthy volunteers, and evaluated using manual traces of a clinical expert as a reference. The 3D meshes obtained with the automatic method were close to the reference contours at all cardiac phases (mean distance of 0.03+/-0.6 mm). The AV plane was detected with an accuracy of -0.6+/-1.0 mm. The LA volumes assessed automatically were also in agreement with the reference (mean +/-1.96 SD): 0.4+/-5.3 ml, 2.1+/-12.6 ml, and 1.5+/-7.8 ml at end-diastolic, end-systolic and pre-atrial-contraction frames, respectively. This study shows that the proposed method can be used for automatic volumetric assessment of the LA, considerably reducing the analysis time and effort when compared to manual analysis.

Infectious endocarditis in pacemaker endocardial leads: report of three cases.

PubMed

Cruz-Cruz, F; Espinola-Zavaleta, N; Hernández Lara, J; Iturralde-Torres, P; González-Hermosillo, J A; Romero-Cárdenas, A; Keirns, C; Vargas-Barrón, J

1999-01-01

Three cases of endocarditis affecting endocardial leads of permanent pacemakers are presented with a review of the literature. Vegetations were identified using transesophageal echocardiography. Infection of pacemaker leads is far less common than infection at the site of the pulse generator with greater morbidity and mortality and generally requiring surgical removal of both electrodes and power source. The most frequent infective agents are stahylococcus varieties.

[Contrast agent improves diagnostic value of dobutamine stress echocardiography].

PubMed

Uehara, H; Yamamoto, T; Hirano, Y; Ozasa, Y; Yamada, S; Ikawa, H; Ishikawa, K

2001-03-01

Suboptimal endocardial definition reduces the diagnostic value of stress echocardiography for coronary artery disease, but intravenous infusion of a left ventricular contrast agent (Albunex) may enhance endocardial border delineation and improve the diagnostic value of dobutamine stress echocardiography. Fifty-six patients, 38 with myocardial infarction, 16 with angina pectoris and two normal subjects, were enrolled in this study. Dobutamine was infused in scalar doses of 5 to 40 micrograms/kg/min. Intravenous infusion of Albunex (0.15 ml/kg) was administered at rest and during peak dobutamine stress during monitoring of the apical four-chamber view. The left ventricle in the apical four-chamber view was divided into six segments and an endocardial delineation score of 0 to 3 (none to excellent visualization) was given to each segment. Endocardial delineation score was increased after Albunex infusion from 2.0 to 2.3 in the basal-septal, 2.0 to 2.4 in the mid-septal, 1.1 to 1.8 in the apical-septal, 0.7 to 1.2 in the apical-lateral, 0.9 to 1.6 in the mid-lateral, and 1.2 to 1.9 in the basal-lateral segments during peak dobutamine administration. Endocardial border resolution in the lateral wall showed greater improvement than in the septal wall after Albunex infusion. Diagnostic values in the left anterior descending artery territory failed to improve with Albunex infusion (sensitivity 82% to 89%, specificity 94% to 89%, and accuracy 86% to 89%), whereas a higher diagnostic accuracy was noted in the left circumflex artery territory with Albunex compared to without Albunex (sensitivity 63% to 81%, specificity 88% to 98%, and accuracy 80% to 93%, p < 0.05). Contrast agent improves the diagnostic accuracy of dobutamine stress echocardiography in the left circumflex artery territory.

Sequential Ligand-Dependent Notch Signaling Activation Regulates Valve Primordium Formation and Morphogenesis.

PubMed

MacGrogan, Donal; D'Amato, Gaetano; Travisano, Stanislao; Martinez-Poveda, Beatriz; Luxán, Guillermo; Del Monte-Nieto, Gonzalo; Papoutsi, Tania; Sbroggio, Mauro; Bou, Vanesa; Gomez-Del Arco, Pablo; Gómez, Manuel Jose; Zhou, Bin; Redondo, Juan Miguel; Jiménez-Borreguero, Luis J; de la Pompa, José Luis

2016-05-13

The Notch signaling pathway is crucial for primitive cardiac valve formation by epithelial-mesenchymal transition, and NOTCH1 mutations cause bicuspid aortic valve; however, the temporal requirement for the various Notch ligands and receptors during valve ontogeny is poorly understood. The aim of this study is to determine the functional specificity of Notch in valve development. Using cardiac-specific conditional targeted mutant mice, we find that endothelial/endocardial deletion of Mib1-Dll4-Notch1 signaling, possibly favored by Manic-Fringe, is specifically required for cardiac epithelial-mesenchymal transition. Mice lacking endocardial Jag1, Notch1, or RBPJ displayed enlarged valve cusps, bicuspid aortic valve, and septal defects, indicating that endocardial Jag1 to Notch1 signaling is required for post-epithelial-mesenchymal transition valvulogenesis. Valve dysmorphology was associated with increased mesenchyme proliferation, indicating that Jag1-Notch1 signaling restricts mesenchyme cell proliferation non-cell autonomously. Gene profiling revealed upregulated Bmp signaling in Jag1-mutant valves, providing a molecular basis for the hyperproliferative phenotype. Significantly, the negative regulator of mesenchyme proliferation, Hbegf, was markedly reduced in Jag1-mutant valves. Hbegf expression in embryonic endocardial cells could be readily activated through a RBPJ-binding site, identifying Hbegf as an endocardial Notch target. Accordingly, addition of soluble heparin-binding EGF-like growth factor to Jag1-mutant outflow tract explant cultures rescued the hyperproliferative phenotype. During cardiac valve formation, Dll4-Notch1 signaling leads to epithelial-mesenchymal transition and cushion formation. Jag1-Notch1 signaling subsequently restrains Bmp-mediated valve mesenchyme proliferation by sustaining Hbegf-EGF receptor signaling. Our studies identify a mechanism of signaling cross talk during valve morphogenesis involved in the origin of congenital heart defects associated with reduced NOTCH function. © 2016 American Heart Association, Inc.

Anisotropic shear stress patterns predict the orientation of convergent tissue movements in the embryonic heart

PubMed Central

2017-01-01

Myocardial contractility and blood flow provide essential mechanical cues for the morphogenesis of the heart. In general, endothelial cells change their migratory behavior in response to shear stress patterns, according to flow directionality. Here, we assessed the impact of shear stress patterns and flow directionality on the behavior of endocardial cells, the specialized endothelial cells of the heart. At the early stages of zebrafish heart valve formation, we show that endocardial cells are converging to the valve-forming area and that this behavior depends upon mechanical forces. Quantitative live imaging and mathematical modeling allow us to correlate this tissue convergence with the underlying flow forces. We predict that tissue convergence is associated with the direction of the mean wall shear stress and of the gradient of harmonic phase-averaged shear stresses, which surprisingly do not match the overall direction of the flow. This contrasts with the usual role of flow directionality in vascular development and suggests that the full spatial and temporal complexity of the wall shear stress should be taken into account when studying endothelial cell responses to flow in vivo. PMID:29183943

An optically coupled system for quantitative monitoring of MRI gradient currents induced into endocardial leads.

PubMed

Mattei, E; Calcagnini, G; Triventi, M; Delogu, A; Del Guercio, M; Angeloni, A; Bartolini, P

2013-01-01

The time-varying gradient fields generated during Magnetic Resonance Imaging (MRI) procedures have the potential to induce electrical current on implanted endocardial leads. Whether this current can result in undesired cardiac stimulation is unknown. This paper presents an optically coupled system with the potential to quantitatively measure the currents induced by the gradient fields into endocardial leads during MRI procedures. Our system is based on a microcontroller that works as analog-to-digital (A/D) converter and sends the current signal acquired from the lead to an optical high-speed light-emitting-diode transmitter. Plastic fiber guides the light outside the MRI chamber, to a photodiode receiver and then to an acquisition board connected to a PC. The preliminary characterization of the performances of the system is also presented.

Newborn infant with maternal anti-SSA antibody-induced complete heart block accompanying cardiomyopathy.

PubMed

Iida, Midori; Inamura, Noboru; Takeuchi, Makoto

2006-01-01

Newborn case of maternal anti-SSA antibody-induced congenital complete heart block (CCHB) accompanying cardiomyopathy is presented. Unexpectedly, she died of ventricular tachycardia, not bradycardia, 6 days after birth. Autopsy revealed left ventricular cardiomyopathy with endocardial fibroelastosis. Thus, when evaluating fetal cardiac performance in cases of maternal anti-SSA antibody-induced CCHB, it is necessary to pay attention to myocardial attributes such as endocardial hyperplasia.

Right Ventricular Outflow Tract Tachycardia with Structural Abnormalities of the Right Ventricle and Left Ventricular Diverticulum.

PubMed

Martini, Bortolo; Trevisi, Nicola; Martini, Nicolò; Zhang, Li

2015-01-01

A 43-year-old woman presented to the emergency room with a sustained ventricular tachycardia (VT). ECG showed a QRS in left bundle branch block morphology with inferior axis. Echocardiography, ventricular angiography, and cardiac magnetic resonance imaging (CMRI) revealed a normal right ventricle and a left ventricular diverticulum. Electrophysiology studies with epicardial voltage mapping identified a large fibrotic area in the inferolateral layer of the right ventricular wall and a small area of fibrotic tissue at the anterior right ventricular outflow tract. VT ablation was successfully performed with combined epicardial and endocardial approaches.

Right Ventricular Outflow Tract Tachycardia with Structural Abnormalities of the Right Ventricle and Left Ventricular Diverticulum

PubMed Central

Martini, Bortolo; Trevisi, Nicola; Martini, Nicolò; Zhang, Li

2015-01-01

A 43-year-old woman presented to the emergency room with a sustained ventricular tachycardia (VT). ECG showed a QRS in left bundle branch block morphology with inferior axis. Echocardiography, ventricular angiography, and cardiac magnetic resonance imaging (CMRI) revealed a normal right ventricle and a left ventricular diverticulum. Electrophysiology studies with epicardial voltage mapping identified a large fibrotic area in the inferolateral layer of the right ventricular wall and a small area of fibrotic tissue at the anterior right ventricular outflow tract. VT ablation was successfully performed with combined epicardial and endocardial approaches. PMID:26509086

Evaluation of left ventricular scar identification from contrast enhanced magnetic resonance imaging for guidance of ventricular catheter ablation therapy

NASA Astrophysics Data System (ADS)

Rettmann, M. E.; Lehmann, H. I.; Johnson, S. B.; Packer, D. L.

2016-03-01

Patients with ventricular arrhythmias typically exhibit myocardial scarring, which is believed to be an important anatomic substrate for reentrant circuits, thereby making these regions a key target in catheter ablation therapy. In ablation therapy, a catheter is guided into the left ventricle and radiofrequency energy is delivered into the tissue to interrupt arrhythmic electrical pathways. Low bipolar voltage regions are typically localized during the procedure through point-by-point construction of an electroanatomic map by sampling the endocardial surface with the ablation catheter and are used as a surrogate for myocardial scar. This process is time consuming, requires significant skill, and has the potential to miss low voltage sites. This has led to efforts to quantify myocardial scar preoperatively using delayed, contrast-enhanced MRI. In this paper, we evaluate the utility of left ventricular scar identification from delayed contrast enhanced magnetic resonance imaging for guidance of catheter ablation of ventricular arrhythmias. Myocardial infarcts were created in three canines followed by a delayed, contrast enhanced MRI scan and electroanatomic mapping. The left ventricle and myocardial scar is segmented from preoperative MRI images and sampled points from the procedural electroanatomical map are registered to the segmented endocardial surface. Sampled points with low bipolar voltage points visually align with the segmented scar regions. This work demonstrates the potential utility of using preoperative delayed, enhanced MRI to identify myocardial scarring for guidance of ventricular catheter ablation therapy.

EVALUATION OF RIGHT AND LEFT VENTRICULAR DIASTOLIC FILLING

PubMed Central

Pasipoularides, Ares

2013-01-01

A conceptual fluid-dynamics framework for diastolic filling is developed. The convective deceleration load (CDL) is identified as an important determinant of ventricular inflow during the E-wave (A-wave) upstroke. Convective deceleration occurs as blood moves from the inflow anulus through larger-area cross-sections toward the expanding walls. Chamber dilatation underlies previously unrecognized alterations in intraventricular flow dynamics. The larger the chamber, the larger become the endocardial surface and the CDL. CDL magnitude affects strongly the attainable E-wave (A-wave) peak. This underlies the concept of diastolic ventriculoannular disproportion. Large vortices, whose strength decreases with chamber dilatation, ensue after the E-wave peak and impound inflow kinetic energy, averting an inflow-impeding, convective Bernoulli pressure-rise. This reduces the CDL by a variable extent depending on vortical intensity. Accordingly, the filling vortex facilitates filling to varying degrees, depending on chamber volume. The new framework provides stimulus for functional genomics research, aimed at new insights into ventricular remodeling. PMID:23585308

Snare coupling of the pre-pectoral pacing lead delivery catheter to the femoral transseptal apparatus for endocardial cardiac resynchronization therapy : mid-term results.

PubMed

Patel, Mehul B; Worley, Seth J

2013-04-01

Limitations imposed by the coronary sinus venous anatomy triggered the transseptal approach for endocardial LV lead placement. The alignment of the interatrial septum (IAS) and its neighborhood anatomy does not favor transseptal puncture from the pre-pectoral area. Locating and advancing a pre-pectoral LV lead delivery catheter (PDC) through an opening created in the IAS via femoral transseptal puncture (FTP) is time consuming and technically difficult. We describe a method where the PDC is snare coupled to the femoral transseptal apparatus (FTA). When the FTA is advanced into the left atrium (LA) the coupled PDC follows. The catheter of a 25-mm loop snare kit is replaced with the PDC (SelectSite®). The snare loop is positioned in the right common iliac vein from the pre-pectoral access. The PDC is coupled to the FTA by advancing the transseptal apparatus through the open snare loop. After conventional FTP, the FTA is withdrawn back into the right atrium (RA) over an extra support wire positioned in the LA. The PDC with open snare loop is pulled over the FTA up to the RA. The PDC is advanced to close the snare loop on the extra support wire immediately distal to the tip of the dilator close to the puncture site. The PDC is deflected to align with the FTA. The snare coupled catheters are gently advanced across the IAS into the LA. The PDC is released from the FTA by advancing the snare and opening the loop; the snare is then removed from the PDC. The PDC is deflected and advanced into the left ventricle (LV). After positioning the 4.1 Fr lumen less LV lead, the PDC is sliced and removed. The PDC snare coupled to the FTA was advanced into the LA in all five patients, however, access was lost during catheter manipulation in the one right-sided case. Endocardial LV lead was successfully positioned in all five patients. Snare coupling the pre-pectoral SelectSite® catheter to the FTA is technically simple, reliable and a safe method for transseptal endocardial LV lead placement for left pre-pectoral implantation.

Effects of coordinate system choice on measured regional myocardial function in short-axis cine electron-beam tomography

NASA Astrophysics Data System (ADS)

Reed, Judd E.; Rumberger, John A.; Buithieu, Jean; Behrenbeck, Thomas; Breen, Jerome F.; Sheedy, Patrick F., II

1995-05-01

Following myocardial infarction, the size of the infarcted region and the systolic functioning of the noninfarcted region are commonly assessed by various cross- sectional imaging techniques. A series of images representing successive phases of the cardiac cycle can be acquired by several imaging modalities including electron beam computed tomography, magnetic resonance imaging, and echocardiography. For the assessment of patterns of ventricular contraction, images are commonly acquired of ventricular cross-sections normal to the 'long' axis of the heart and parallel to the mitral valve plane. The endocardial and epicardial surfaces of the myocardium are identified. Then the ventricle is divided into sectors and the volumes of blood and myocardium within each sector at multiple phases of the cardiac cycle are measured. Regional function parameters are derived from these measurements. This generally mandates the use of a polar or cylindrical coordinate system. Various algorithms have been used to select the origin of this coordinate system. These include the centroid of the endocardial surface, the epicardial surface, or of a polygon whose vertices lie midway between the epicardial and endocardial surfaces of the myocardium (centerline method). Another algorithm has been developed in our laboratory. This uses the centroid (or center of mass) of the myocardium exclusive of the ventricular cavity. Each of these choices for origin of coordinate system can be derived from the end- diastolic image or from the end-systolic image. Alternately, new coordinate systems can be selected for each phase of the cardiac cycle. These are referred to as 'floating' coordinate systems. A series of computer models have been developed in our laboratory to study the effects of each of these choices on the regional function parameters of normal ventricles and how these choices effect the quantification of regional abnormalities after myocardial infarction. The most sophisticated of these is an interactive program with a graphical user interface which facilitates the simulation of a wide variety of dynamic ventricular cross sections. Analysis of these simulations has led to a better understanding of how polar coordinate system placement influences the results of quantitative regional ventricular function assessment. It has also created new insight into how the appropriateness of the placement of such a polar coordinate systems can be objectively assessed. The validity of the conclusions drawn from the analysis of simulated ventricular shapes was validated through the analysis of outlines extracted from cine electron beam computed tomographic images. This was done using another interactive software tool developed specifically for this purpose. With this tool, the effects on regional function parameters of various choices for origin placement can be directly observed. This has proven to reinforce the conclusions drawn from the simulations and has led to the modification of the procedures used in our laboratory. Conclusions: The so-called floating coordinate systems are superior to fixed ones for quantification of regional left ventricular contraction in almost every respect. The use of regional ejection fractions with a coordinate system origin located at the centroid of the endocardial surface can lead to 180 degree errors in identifying the location of a myocardial infarction. This problem is less pronounced with midline and epicardium- based centroids and does not occur when the centroid of the myocardium is used. The quantified migration of myocardial mass across sector boundaries is a useful indicator of an inappropriate choice of coordinate system origin. When the centroid of the myocardium falls well within the ventricular cavity, as it usually does, it is a better location for the origin for regional analysis than any of the other centroids analyzed.

Conformal phased surfaces for wireless powering of bioelectronic microdevices

PubMed Central

Agrawal, Devansh R.; Tanabe, Yuji; Weng, Desen; Ma, Andrew; Hsu, Stephanie; Liao, Song-Yan; Zhen, Zhe; Zhu, Zi-Yi; Sun, Chuanbowen; Dong, Zhenya; Yang, Fengyuan; Tse, Hung Fat; Poon, Ada S. Y.; Ho, John S.

2017-01-01

Wireless powering could enable the long-term operation of advanced bioelectronic devices within the human body. Although both enhanced powering depth and device miniaturization can be achieved by shaping the field pattern within the body, existing electromagnetic structures do not provide the spatial phase control required to synthesize such patterns. Here, we describe the design and operation of conformal electromagnetic structures, termed phased surfaces, that interface with non-planar body surfaces and optimally modulate the phase response to enhance the performance of wireless powering. We demonstrate that the phased surfaces can wirelessly transfer energy across anatomically heterogeneous tissues in large animal models, powering miniaturized semiconductor devices (<12 mm3) deep within the body (>4 cm). As an illustration of in vivo operation, we wirelessly regulated cardiac rhythm by powering miniaturized stimulators at multiple endocardial sites in a porcine animal model. PMID:29226018

Regional cardiac wall motion from gated myocardial perfusion SPECT studies

NASA Astrophysics Data System (ADS)

Smith, M. F.; Brigger, P.; Ferrand, S. K.; Dilsizian, V.; Bacharach, S. L.

1999-06-01

A method for estimating regional epicardial and endocardial wall motion from gated myocardial perfusion SPECT studies has been developed. The method uses epicardial and endocardial boundaries determined from four long-axis slices at each gate of the cardiac cycle. The epicardial and endocardial wall position at each time gate is computed with respect to stationary reference ellipsoids, and wall motion is measured along lines normal to these ellipsoids. An initial quantitative evaluation of the method was made using the beating heart from the dynamic mathematical cardiac torso (MCAT) phantom, with and without a 1.5-cm FWHM Gaussian blurring filter. Epicardial wall motion was generally well-estimated within a fraction of a 3.56-mm voxel, although apical motion was overestimated with the Gaussian filter. Endocardial wall motion was underestimated by about two voxels with and without the Gaussian filter. The MCAT heart phantom was modified to model hypokinetic and dyskinetic wall motion. The wall motion analysis method enabled this abnormal motion to be differentiated from normal motion. Regional cardiac wall motion also was analyzed for /sup 201/Tl patient studies. Estimated wall motion was consistent with a nuclear medicine physician's visual assessment of motion from gated long-axis slices for male and female study examples. Additional research is required for a comprehensive evaluation of the applicability of the method to patient studies with normal and abnormal wall motion.

Novel MRI-derived quantitative biomarker for cardiac function applied to classifying ischemic cardiomyopathy within a Bayesian rule learning framework

NASA Astrophysics Data System (ADS)

Menon, Prahlad G.; Morris, Lailonny; Staines, Mara; Lima, Joao; Lee, Daniel C.; Gopalakrishnan, Vanathi

2014-03-01

Characterization of regional left ventricular (LV) function may have application in prognosticating timely response and informing choice therapy in patients with ischemic cardiomyopathy. The purpose of this study is to characterize LV function through a systematic analysis of 4D (3D + time) endocardial motion over the cardiac cycle in an effort to define objective, clinically useful metrics of pathological remodeling and declining cardiac performance, using standard cardiac MRI data for two distinct patient cohorts accessed from CardiacAtlas.org: a) MESA - a cohort of asymptomatic patients; and b) DETERMINE - a cohort of symptomatic patients with a history of ischemic heart disease (IHD) or myocardial infarction. The LV endocardium was segmented and a signed phase-to-phase Hausdorff distance (HD) was computed at 3D uniformly spaced points tracked on segmented endocardial surface contours, over the cardiac cycle. An LV-averaged index of phase-to-phase endocardial displacement (P2PD) time-histories was computed at each tracked point, using the HD computed between consecutive cardiac phases. Average and standard deviation in P2PD over the cardiac cycle was used to prepare characteristic curves for the asymptomatic and IHD cohort. A novel biomarker of RMS error between mean patient-specific characteristic P2PD over the cardiac cycle for each individual patient and the cumulative P2PD characteristic of a cohort of asymptomatic patients was established as the RMS-P2PD marker. The novel RMS-P2PD marker was tested as a cardiac function based feature for automatic patient classification using a Bayesian Rule Learning (BRL) framework. The RMS-P2PD biomarker indices were significantly different for the symptomatic patient and asymptomatic control cohorts (p<0.001). BRL accurately classified 83.8% of patients correctly from the patient and control populations, with leave-one-out cross validation, using standard indices of LV ejection fraction (LV-EF) and LV end-systolic volume index (LV-ESVI). This improved to 91.9% with inclusion of the RMS-P2PD biomarker and was congruent with improvements in both sensitivity for classifying patients and specificity for identifying asymptomatic controls from 82.6% up to 95.7%. RMS-P2PD, when contrasted against a collective normal reference, is a promising biomarker to investigate further in its utility for identifying quantitative signs of pathological endocardial function which may boost standard image makers as precursors of declining cardiac performance.

Endocardial Energy Harvesting by Electromagnetic Induction.

PubMed

Zurbuchen, Adrian; Haeberlin, Andreas; Bereuter, Lukas; Pfenniger, Alois; Bosshard, Simon; Kernen, Micha; Philipp Heinisch, Paul; Fuhrer, Juerg; Vogel, Rolf

2018-02-01

cardiac pacemakers require regular medical follow-ups to ensure proper functioning. However, device replacements due to battery depletion are common and account for ∼25% of all implantation procedures. Furthermore, conventional pacemakers require pacemaker leads which are prone to fractures, dislocations or isolation defects. The ensuing surgical interventions increase risks for the patients and costs that need to be avoided. in this study, we present a method to harvest energy from endocardial heart motions. We developed a novel generator, which converts the heart's mechanical into electrical energy by electromagnetic induction. A mathematical model has been introduced to identify design parameters strongly related to the energy conversion efficiency of heart motions and fit the geometrical constraints for a miniaturized transcatheter deployable device. The implemented final design was tested on the bench and in vivo. the mathematical model proved an accurate method to estimate the harvested energy. For three previously recorded heart motions, the model predicted a mean output power of 14.5, 41.9, and 16.9 μW. During an animal experiment, the implanted device harvested a mean output power of 0.78 and 1.7 μW at a heart rate of 84 and 160 bpm, respectively. harvesting kinetic energy from endocardial motions seems feasible. Implanted at an energetically favorable location, such systems might become a welcome alternative to extend the lifetime of cardiac implantable electronic device. the presented endocardial energy harvesting concept has the potential to turn pacemakers into battery- and leadless systems and thereby eliminate two major drawbacks of contemporary systems.

Endocardial fibrosarcoma in a reticulated python (Python reticularis).

PubMed

Gumber, Sanjeev; Nevarez, Javier G; Cho, Doo-Youn

2010-11-01

A female, reticulated python (Python reticularis) of unknown age was presented with a history of lethargy, weakness, and distended coelom. Physical examination revealed severe dystocia and stomatitis. The reticulated python was euthanized due to a poor clinical prognosis. Postmortem examination revealed marked distention of the reproductive tract with 26 eggs (10-12 cm in diameter), pericardial effusion, and a slightly firm, pale tan mass (3-4 cm in diameter) adhered to the endocardium at the base of aorta. Based on histopathologic and transmission electron microscopic findings, the diagnosis of endocardial fibrosarcoma was made.

Left Atrial Appendage Closure for Stroke Prevention: Devices, Techniques, and Efficacy.

PubMed

Iskandar, Sandia; Vacek, James; Lavu, Madhav; Lakkireddy, Dhanunjaya

2016-05-01

Left atrial appendage closure can be performed either surgically or percutaneously. Surgical approaches include direct suture, excision and suture, stapling, and clipping. Percutaneous approaches include endocardial, epicardial, and hybrid endocardial-epicardial techniques. Left atrial appendage anatomy is highly variable and complex; therefore, preprocedural imaging is crucial to determine device selection and sizing, which contribute to procedural success and reduction of complications. Currently, the WATCHMAN is the only device that is approved for left atrial appendage closure in the United States. Copyright © 2016 Elsevier Inc. All rights reserved.

Echocardiographic measurements of left ventricular mass by a non-geometric method

NASA Technical Reports Server (NTRS)

Parra, Beatriz; Buckey, Jay; Degraff, David; Gaffney, F. Andrew; Blomqvist, C. Gunnar

1987-01-01

The accuracy of a new nongeometric method for calculating left ventricular myocardial volumes from two-dimensional echocardiographic images was assessed in vitro using 20 formalin-fixed normal human hearts. Serial oblique short-axis images were acquired from one point at 5-deg intervals, for a total of 10-12 cross sections. Echocardiographic myocardial volumes were calculated as the difference between the volumes defined by the epi- and endocardial surfaces. Actual myocardial volumes were determined by water displacement. Volumes ranged from 80 to 174 ml (mean 130.8 ml). Linear regression analysis demonstrated excellent agreement between the echocardiographic and direct measurements.

Endocardial left ventricle feature tracking and reconstruction from tri-plane trans-esophageal echocardiography data

NASA Astrophysics Data System (ADS)

Dangi, Shusil; Ben-Zikri, Yehuda K.; Cahill, Nathan; Schwarz, Karl Q.; Linte, Cristian A.

2015-03-01

Two-dimensional (2D) ultrasound (US) has been the clinical standard for over two decades for monitoring and assessing cardiac function and providing support via intra-operative visualization and guidance for minimally invasive cardiac interventions. Developments in three-dimensional (3D) image acquisition and transducer design and technology have revolutionized echocardiography imaging enabling both real-time 3D trans-esophageal and intra-cardiac image acquisition. However, in most cases the clinicians do not access the entire 3D image volume when analyzing the data, rather they focus on several key views that render the cardiac anatomy of interest during the US imaging exam. This approach enables image acquisition at a much higher spatial and temporal resolution. Two such common approaches are the bi-plane and tri-plane data acquisition protocols; as their name states, the former comprises two orthogonal image views, while the latter depicts the cardiac anatomy based on three co-axially intersecting views spaced at 600 to one another. Since cardiac anatomy is continuously changing, the intra-operative anatomy depicted using real-time US imaging also needs to be updated by tracking the key features of interest and endocardial left ventricle (LV) boundaries. Therefore, rapid automatic feature tracking in US images is critical for three reasons: 1) to perform cardiac function assessment; 2) to identify location of surgical targets for accurate tool to target navigation and on-target instrument positioning; and 3) to enable pre- to intra-op image registration as a means to fuse pre-op CT or MR images used during planning with intra-operative images for enhanced guidance. In this paper we utilize monogenic filtering, graph-cut based segmentation and robust spline smoothing in a combined work flow to process the acquired tri-plane TEE time series US images and demonstrate robust and accurate tracking of the LV endocardial features. We reconstruct the endocardial LV geometry using the tri-plane contours and spline interpolation, and assess the accuracy of the proposed work flow against gold-standard results from the GE Echopac PC clinical software according to quantitative clinical LV characterization parameters, such as the length, circumference, area and volume. Our proposed combined work flow leads to consistent, rapid and automated identification of the LV endocardium, suitable for intra-operative applications and "on-the-fly" computer-assisted assessment of ejection fraction for cardiac function monitoring.Two-dimensional (2D) ultrasound (US) has been the clinical standard for over two decades for monitoring and assessing cardiac function and providing support via intra-operative visualization and guidance for minimally invasive cardiac interventions. Developments in three-dimensional (3D) image acquisition and transducer design and technology have revolutionized echocardiography imaging enabling both real-time 3D trans-esophageal and intra-cardiac image acquisition. However, in most cases the clinicians do not access the entire 3D image volume when analyzing the data, rather they focus on several key views that render the cardiac anatomy of interest during the US imaging exam. This approach enables image acquisition at a much higher spatial and temporal resolution. Two such common approaches are the bi-plane and tri-plane data acquisition protocols; as their name states, the former comprises two orthogonal image views, while the latter depicts the cardiac anatomy based on three co-axially intersecting views spaced at 600 to one another. Since cardiac anatomy is continuously changing, the intra-operative anatomy depicted using real-time US imaging also needs to be updated by tracking the key features of interest and endocardial left ventricle (LV) boundaries. Therefore, rapid automatic feature tracking in US images is critical for three reasons: 1) to perform cardiac function assessment; 2) to identify location of surgical targets for accurate tool to target navigation and on-target instrument positioning; and 3) to enable pre- to intra-op image registration as a means to fuse pre-op CT or MR images used during planning with intra-operative images for enhanced guidance. In this paper we utilize monogenic filtering, graph-cut based segmentation and robust spline smoothing in a combined work flow to process the acquired tri-plane TEE time series US images and demonstrate robust and accurate tracking of the LV endocardial features. We reconstruct the endocardial LV geometry using the tri-plane contours and spline interpolation, and assess the accuracy of the proposed work flow against gold-standard results from the GE Echopac PC clinical software according to quantitative clinical LV characterization parameters, such as the length, circumference, area and volume. Our proposed combined work flow leads to consistent, rapid and automated identification of the LV endocardium, suitable for intra-operative applications and on-the- y" computer-assisted assessment of ejection fraction for cardiac function monitoring.

Absence of Rapid Propagation through the Purkinje Network as a Potential Cause of Line Block in the Human Heart with Left Bundle Branch Block.

PubMed

Okada, Jun-Ichi; Washio, Takumi; Nakagawa, Machiko; Watanabe, Masahiro; Kadooka, Yoshimasa; Kariya, Taro; Yamashita, Hiroshi; Yamada, Yoko; Momomura, Shin-Ichi; Nagai, Ryozo; Hisada, Toshiaki; Sugiura, Seiryo

2018-01-01

Background: Cardiac resynchronization therapy is an effective device therapy for heart failure patients with conduction block. However, a problem with this invasive technique is the nearly 30% of non-responders. A number of studies have reported a functional line of block of cardiac excitation propagation in responders. However, this can only be detected using non-contact endocardial mapping. Further, although the line of block is considered a sign of responders to therapy, the mechanism remains unclear. Methods: Herein, we created two patient-specific heart models with conduction block and simulated the propagation of excitation based on a cellmodel of electrophysiology. In one model with a relatively narrow QRS width (176 ms), we modeled the Purkinje network using a thin endocardial layer with rapid conduction. To reproduce a wider QRS complex (200 ms) in the second model, we eliminated the Purkinje network, and we simulated the endocardial mapping by solving the inverse problem according to the actual mapping system. Results: We successfully observed the line of block using non-contact mapping in the model without the rapid propagation of excitation through the Purkinje network, although the excitation in the wall propagated smoothly. This model of slow conduction also reproduced the characteristic properties of the line of block, including dense isochronal lines and fractionated local electrocardiograms. Further, simulation of ventricular pacing from the lateral wall shifted the location of the line of block. By contrast, in the model with the Purkinje network, propagation of excitation in the endocardial map faithfully followed the actual propagation in the wall, without showing the line of block. Finally, switching the mode of propagation between the two models completely reversed these findings. Conclusions: Our simulation data suggest that the absence of rapid propagation of excitation through the Purkinje network is the major cause of the functional line of block recorded by non-contact endocardial mapping. The line of block can be used to identify responders as these patients loose rapid propagation through the Purkinje network.

Ellis-van Creveld syndrome: prenatal diagnosis, molecular analysis and genetic counseling.

PubMed

Chen, Chih-Ping; Su, Yi-Ning; Hsu, Chin-Yuan; Chern, Schu-Rern; Tsai, Fuu-Jen; Wu, Pei-Chen; Chen, Po-Tsang; Wang, Wayseen

2010-12-01

To present the perinatal findings and molecular genetic analysis of two siblings with Ellis-van Creveld (EvC) syndrome. A 33-year-old woman, gravida 3, para 1, was referred for genetic counseling at 18 gestational weeks because of recurrent fetal skeletal dysplasia. Two years previously, she had delivered a 1,316-g dead male baby at 28 gestational weeks with a karyotype of 46,XY, postaxial polydactyly of the hands, thoracic narrowness, endocardial cushion defects, transposition of the great arteries, shortening of the long bones, malposition of the toes, and hypoplastic nails. During this pregnancy, prenatal ultrasound at 18 gestational weeks revealed shortening of the long bones (equivalent to 15 weeks), postaxial polydactyly of both hands, thoracic narrowness, and endocardial cushion defects. The pregnancy was subsequently terminated, and a 236-g female fetus was delivered with a karyotype of 46,XX, postaxial polydactyly of the hands, thoracic dysplasia, endocardial cushion defects, shortening of the long bones, and malposition of the toes and hypoplastic nails. The phenotype of each of the two siblings was consistent with EVC syndrome. Molecular analysis of the EVC and EVC2 genes revealed heterozygous mutations in the EVC2 gene. A heterozygous deletion mutation of a 26-bp deletion of c.871-2_894del26 encompassing the junction between intron 7 and exon 8 of the EVC2 gene was found in the mother and two siblings, and a heterozygous nonsense mutation of c.1195C >T, p.R399X in exon 10 of the EVC2 gene was found in the father and two siblings. Prenatal sonographic identification of endocardial cushion defects in association with shortening of the long bones should alert clinicians to the possibility of EvC syndrome and prompt a careful search of hexadactyly of the hands. Molecular analysis of the EVC and EVC2 genes is helpful in genetic counseling in cases with prenatally detected postaxial polydactyly, thoracic narrowness, short limbs and endocardial cushion defects. Copyright © 2010 Taiwan Association of Obstetric & Gynecology. Published by Elsevier B.V. All rights reserved.

Results of endocardial radiofrequency ablation of atrial fibrillation during mitral valve surgery.

PubMed

Demirkilic, U; Bolcal, C; Gunay, C; Doganci, S; Temizkan, V; Kuralay, E; Tatar, H

2006-08-01

The aim of the study is to evaluate the efficacy of thermocontrolled endocardial radiofrequency (RF) ablation for the patients with mitral valve disorder and associated chronic atrial fibrillation during mitral valve replacement operation. Between February 2002 and January 2004, 43 patients with mitral valve disease and associated chronic atrial fibrillation underwent mitral valve replacement and thermocontrolled endocardial RF ablation with Cobra RF system flexible probe at Gulhane Military Academy of Medicine, Department of Cardiovascular Surgery. Eighteen of the patients (41.8%) were males, while the remaining 25 (58.2%) were females. The average age of the patients was 44+/-14.21 (18-66) years. Functional capacity of the patients was class II in 15 (34. 9%), class III in 24 (55.8%), class IV in 4 (9.3%) according to the NYHA classification. At the preoperative period all of the patients were evaluated routinely by twelve-lead ECG, chest film and transthoracic echocardiography (TTE). For the patients over 40 years of age, we performed additional coronary angiography to delineate any coronary lesions. The patients were evaluated at months 1, 3, 6 and annually by twelve-lead ECG, TTE and holter monitoring after discharge. There were not any complications related to the performed technique. No operative and hospital mortality were recorded. At the follow-up period for 35 of 43 patients (81.4%) sinus rhythm was restored. The mean follow-up time was 24.3+/-11.2 (12-35) months. Endocardial RF ablation especially during mitral valve surgery is a simple technique to be performed. Early and midterm results of the cohort are satisfying.

Canine left ventricle electromechanical behavior under different pacing modes.

PubMed

Vo Thang, Thanh-Thuy; Thibault, Bernard; Finnerty, Vincent; Pelletier-Galarneau, Matthieu; Khairy, Paul; Grégoire, Jean; Harel, François

2012-10-01

Cardiac resynchronization therapy may improve survival and quality of life in patients suffering from heart failure with left ventricular (LV) contraction dyssynchrony. While several studies have investigated electrical or mechanical determinants of synchronous contraction, few have focused on activation contraction coupling at a macroscopic level. The objective of the study was to characterize LV electromechanical behavior and response to pacing in a heart failure model. We analyzed data from 3D electroanatomic non-contact mapping and blood pool SPECT for 12 dogs with right ventricular (RV) tachycardia pacing-induced dilated cardiomyopathy. Surfaces generated by the two modalities were registered. Electrical signals were analyzed, and endocardial wall displacement curves were portrayed. Rapid pacing decreased the mean LV ejection fraction (LVEF) to 20.9 % and prolonged the QRS duration to 79 ± 10 ms (normal range: 40-50 ms). QRS duration remained unchanged with biventricular pacing (88.5 ms), while single site pacing further prolonged the QRS duration (113.3 ms for RV pacing and 111.6 ms for LV pacing). No trend was observed in LV systolic function. Activation duration time was significantly increased with all pacing modes compared to baseline. Finally, electromechanical delay, as defined by the delay between electrical activation and mechanical response, was increased by single site pacing (172.9 ms for RV pacing and 174.6 ms for LV pacing) but not by biventricular pacing (162.4 ms). Combined temporal and spatial coregistration electroanatomic maps and baseline gated blood pool SPECT imaging allowed us to quantify activation duration time, electromechanical delay, and LVEF for different pacing modes. Even if pacing modes did not significantly modify LVEF or activation duration, they produced alterations in electromechanical delay, with biventricular pacing significantly decreasing the electromechanical delay as measured by surface tracings and endocardial non-contact mapping.

Retinoic Acid Signaling Is Essential for Valvulogenesis by Affecting Endocardial Cushions Formation in Zebrafish Embryos.

PubMed

Li, Junbo; Yue, Yunyun; Zhao, Qingshun

2016-02-01

Retinoic acid (RA) plays important roles in many stages of heart morphogenesis. Zebrafish embryos treated with exogenous RA display defective atrio-ventricular canal (AVC) specification. However, whether endogenous RA signaling takes part in cardiac valve formation remains unknown. Herein, we investigated the role of RA signaling in cardiac valve development by knocking down aldh1a2, the gene encoding an enzyme that is mainly responsible for RA synthesis during early development, in zebrafish embryos. The results showed that partially knocking down aldh1a2 caused defective formation of primitive cardiac valve leaflets at 108 hpf (hour post-fertilization). Inhibiting endogenous RA signaling by 4-diethylaminobenzal-dehyde revealed that 16-26 hpf was a key time window when RA signaling affects the valvulogenesis. The aldh1a2 morphants had defective formation of endocardial cushion (EC) at 76 hpf though they had almost normal hemodynamics and cardiac chamber specification at early development. Examining the expression patterns of AVC marker genes including bmp4, bmp2b, nppa, notch1b, and has2, we found the morphants displayed abnormal development of endocardial AVC but almost normal development of myocardial AVC at 50 hpf. Being consistent with the reduced expression of notch1b in endocardial AVC, the VE-cadherin gene cdh5, the downstream gene of Notch signaling, was ectopically expressed in AVC of aldh1a2 morphants at 50 hpf, and overexpression of cdh5 greatly affected the formation of EC in the embryos at 76 hpf. Taken together, our results suggest that RA signaling plays essential roles in zebrafish cardiac valvulogenesis.

A Novel Feature-Tracking Echocardiographic Method for the Quantitation of Regional Myocardial Function

PubMed Central

Pirat, Bahar; Khoury, Dirar S.; Hartley, Craig J.; Tiller, Les; Rao, Liyun; Schulz, Daryl G.; Nagueh, Sherif F.; Zoghbi, William A.

2012-01-01

Objectives The aim of this study was to validate a novel, angle-independent, feature-tracking method for the echocardiographic quantitation of regional function. Background A new echocardiographic method, Velocity Vector Imaging (VVI) (syngo Velocity Vector Imaging technology, Siemens Medical Solutions, Ultrasound Division, Mountain View, California), has been introduced, based on feature tracking—incorporating speckle and endocardial border tracking, that allows the quantitation of endocardial strain, strain rate (SR), and velocity. Methods Seven dogs were studied during baseline, and various interventions causing alterations in regional function: dobutamine, 5-min coronary occlusion with reperfusion up to 1 h, followed by dobutamine and esmolol infusions. Echocardiographic images were acquired from short- and long-axis views of the left ventricle. Segment-length sonomicrometry crystals were used as the reference method. Results Changes in systolic strain in ischemic segments were tracked well with VVI during the different states of regional function. There was a good correlation between circumferential and longitudinal systolic strain by VVI and sonomicrometry (r = 0.88 and r = 0.83, respectively, p < 0.001). Strain measurements in the nonischemic basal segments also demonstrated a significant correlation between the 2 methods (r = 0.65, p < 0.001). Similarly, a significant relation was observed for circumferential and longitudinal SR between the 2 methods (r = 0.94, p < 0.001 and r = 0.90, p < 0.001, respectively). The endocardial velocity relation to changes in strain by sonomicrometry was weaker owing to significant cardiac translation. Conclusions Velocity Vector Imaging, a new feature-tracking method, can accurately assess regional myocardial function at the endocardial level and is a promising clinical tool for the simultaneous quantification of regional and global myocardial function. PMID:18261685

A novel feature-tracking echocardiographic method for the quantitation of regional myocardial function: validation in an animal model of ischemia-reperfusion.

PubMed

Pirat, Bahar; Khoury, Dirar S; Hartley, Craig J; Tiller, Les; Rao, Liyun; Schulz, Daryl G; Nagueh, Sherif F; Zoghbi, William A

2008-02-12

The aim of this study was to validate a novel, angle-independent, feature-tracking method for the echocardiographic quantitation of regional function. A new echocardiographic method, Velocity Vector Imaging (VVI) (syngo Velocity Vector Imaging technology, Siemens Medical Solutions, Ultrasound Division, Mountain View, California), has been introduced, based on feature tracking-incorporating speckle and endocardial border tracking, that allows the quantitation of endocardial strain, strain rate (SR), and velocity. Seven dogs were studied during baseline, and various interventions causing alterations in regional function: dobutamine, 5-min coronary occlusion with reperfusion up to 1 h, followed by dobutamine and esmolol infusions. Echocardiographic images were acquired from short- and long-axis views of the left ventricle. Segment-length sonomicrometry crystals were used as the reference method. Changes in systolic strain in ischemic segments were tracked well with VVI during the different states of regional function. There was a good correlation between circumferential and longitudinal systolic strain by VVI and sonomicrometry (r = 0.88 and r = 0.83, respectively, p < 0.001). Strain measurements in the nonischemic basal segments also demonstrated a significant correlation between the 2 methods (r = 0.65, p < 0.001). Similarly, a significant relation was observed for circumferential and longitudinal SR between the 2 methods (r = 0.94, p < 0.001 and r = 0.90, p < 0.001, respectively). The endocardial velocity relation to changes in strain by sonomicrometry was weaker owing to significant cardiac translation. Velocity Vector Imaging, a new feature-tracking method, can accurately assess regional myocardial function at the endocardial level and is a promising clinical tool for the simultaneous quantification of regional and global myocardial function.

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

PubMed

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

2012-01-01

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

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

PubMed Central

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

2012-01-01

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

Incremental value of contrast echocardiography in the evaluation of a cardiac thrombus.

PubMed

Po, Jose Ricardo F; Tong, Matthew S; Grove, Erica L; Biederman, Robert W W

2017-02-01

A 52-year-old man presented with altered mental status and report of prior complaint of chest pain. On electrocardiography, anterolateral ST-segment elevations with Q-waves in the septal leads were seen. Initial echocardiography images demonstrated a thickened anteroseptum. Further imaging showed the presence of a well-attached laminated apical thrombus. Contrast echocardiography images showed that the thrombus had minimal attachment to the endocardial surface. CT head subsequently showed the presence of acute stroke. The case demonstrates the additional value of contrast echocardiography in the evaluation of cardiac masses despite the certainty in the diagnosis of a thrombus. © 2017, Wiley Periodicals, Inc.

Real-time 3D visualization of cellular rearrangements during cardiac valve formation

PubMed Central

Pestel, Jenny; Ramadass, Radhan; Gauvrit, Sebastien; Helker, Christian; Herzog, Wiebke

2016-01-01

During cardiac valve development, the single-layered endocardial sheet at the atrioventricular canal (AVC) is remodeled into multilayered immature valve leaflets. Most of our knowledge about this process comes from examining fixed samples that do not allow a real-time appreciation of the intricacies of valve formation. Here, we exploit non-invasive in vivo imaging techniques to identify the dynamic cell behaviors that lead to the formation of the immature valve leaflets. We find that in zebrafish, the valve leaflets consist of two sets of endocardial cells at the luminal and abluminal side, which we refer to as luminal cells (LCs) and abluminal cells (ALCs), respectively. By analyzing cellular rearrangements during valve formation, we observed that the LCs and ALCs originate from the atrium and ventricle, respectively. Furthermore, we utilized Wnt/β-catenin and Notch signaling reporter lines to distinguish between the LCs and ALCs, and also found that cardiac contractility and/or blood flow is necessary for the endocardial expression of these signaling reporters. Thus, our 3D analyses of cardiac valve formation in zebrafish provide fundamental insights into the cellular rearrangements underlying this process. PMID:27302398

A 3D Hermite-based multiscale local active contour method with elliptical shape constraints for segmentation of cardiac MR and CT volumes.

PubMed

Barba-J, Leiner; Escalante-Ramírez, Boris; Vallejo Venegas, Enrique; Arámbula Cosío, Fernando

2018-05-01

Analysis of cardiac images is a fundamental task to diagnose heart problems. Left ventricle (LV) is one of the most important heart structures used for cardiac evaluation. In this work, we propose a novel 3D hierarchical multiscale segmentation method based on a local active contour (AC) model and the Hermite transform (HT) for LV analysis in cardiac magnetic resonance (MR) and computed tomography (CT) volumes in short axis view. Features such as directional edges, texture, and intensities are analyzed using the multiscale HT space. A local AC model is configured using the HT coefficients and geometrical constraints. The endocardial and epicardial boundaries are used for evaluation. Segmentation of the endocardium is controlled using elliptical shape constraints. The final endocardial shape is used to define the geometrical constraints for segmentation of the epicardium. We follow the assumption that epicardial and endocardial shapes are similar in volumes with short axis view. An initialization scheme based on a fuzzy C-means algorithm and mathematical morphology was designed. The algorithm performance was evaluated using cardiac MR and CT volumes in short axis view demonstrating the feasibility of the proposed method.

Real-time 3D visualization of cellular rearrangements during cardiac valve formation.

PubMed

Pestel, Jenny; Ramadass, Radhan; Gauvrit, Sebastien; Helker, Christian; Herzog, Wiebke; Stainier, Didier Y R

2016-06-15

During cardiac valve development, the single-layered endocardial sheet at the atrioventricular canal (AVC) is remodeled into multilayered immature valve leaflets. Most of our knowledge about this process comes from examining fixed samples that do not allow a real-time appreciation of the intricacies of valve formation. Here, we exploit non-invasive in vivo imaging techniques to identify the dynamic cell behaviors that lead to the formation of the immature valve leaflets. We find that in zebrafish, the valve leaflets consist of two sets of endocardial cells at the luminal and abluminal side, which we refer to as luminal cells (LCs) and abluminal cells (ALCs), respectively. By analyzing cellular rearrangements during valve formation, we observed that the LCs and ALCs originate from the atrium and ventricle, respectively. Furthermore, we utilized Wnt/β-catenin and Notch signaling reporter lines to distinguish between the LCs and ALCs, and also found that cardiac contractility and/or blood flow is necessary for the endocardial expression of these signaling reporters. Thus, our 3D analyses of cardiac valve formation in zebrafish provide fundamental insights into the cellular rearrangements underlying this process. © 2016. Published by The Company of Biologists Ltd.

Speckle tracking echocardiography to assess regional ventricular function in patients with apical hypertrophic cardiomyopathy.

PubMed

Saccheri, María Cristina; Cianciulli, Tomás Francisco; Morita, Luis Alberto; Méndez, Ricardo José; Beck, Martín Alejandro; Guerra, Juan Enrique; Cozzarin, Alberto; Puente, Luciana Jimena; Balletti, Lorena Romina; Lax, Jorge Alberto

2017-04-26

To explore regional systolic strain of midwall and endocardial segments using speckle tracking echocardiography in patients with apical hypertrophic cardiomyopathy (HCM). We prospectively assessed 20 patients (mean age 53 ± 16 years, range: 18-81 years, 10 were male), with apical HCM. We measured global longitudinal peak systolic strain (GLPSS) in the midwall and endocardium of the left ventricle. The diastolic thickness of the 4 apical segments was 16.25 ± 2.75 mm. All patients had a normal global systolic function with a fractional shortening of 50% ± 8%. In spite of supernormal left ventricular (LV) systolic function, midwall GLPSS was decreased in all patients, more in the apical (-7.3% ± -8.8%) than in basal segments (-15.5% ± -6.93%), while endocardial GLPPS was significantly greater and reached normal values (apical: -22.8% ± -7.8%, basal: -17.9% ± -7.5%). This study shows that two-dimensional strain was decreased mainly confined to the mesocardium, while endocardium myocardial deformation was preserved in HCM and allowed to identify subclinical LV dysfunction. This transmural heterogeneity in systolic strain had not been previously described in HCM and could be explained by the distribution of myofibrillar disarray in deep myocardial areas. The clinical application of this novel finding may help further understanding of the pathophysiology of HCM.

A Case of Loeffler Endocarditis That Showed Endomyocardial Systolic Dysfunction Detected by Layer Specific Strain Analysis.

PubMed

Jin, Xuanyi; Ma, Chunyan; Wang, Yonghuai; Yang, Jun

2017-12-12

Loeffler endocarditis is a rare comprehensive cardiac manifestation caused by eosinophilic cell infiltrations and is present in 50%-60% of patients with hypereosinophilic syndrome (HES). Left ventricle (LV) endocardial systolic dysfunction is a major cause of morbidity and mortality in HES and Loeffler endocarditis. We present a case of Loeffler endocarditis, whose left ventricular (LV) systolic dysfunction and endocardial systolic dysfunction were first neglected by conventional transthoracic echocardiography (TTE), but were later pointed out by layer-specific longitudinal strain analysis. With timely initial therapeutic management, the patient's outcome was remarkable. Thus, we strongly recommend strain analysis as a necessary supplementary test of conventional TTE in all patients with Loeffler endocarditis.

[Impact of CHA2DS2 VASc score on substrate for persistent atrial fibrillation and outcome post catheter ablation of atrial fibrillation].

PubMed

Ribo, Tang; Jianzeng, Dong; Xiaohui, Liu; Meisheng, Shang; Ronghui, Yu; Deyong, Long; Xin, Du; Junping, Kang; Jiahui, Wu; Man, Ning; Caihua, Sang; Chenxi, Jiang; Rong, Bai; Songnan, Li; Yan, Yao; Songnan, Wen; Changsheng, Ma

2015-08-01

To explore if CHA2DS2 VASc score can predict substrate for persistent atrial fibrillation ( AF) and outcome post catheter ablation of AF. From January 2011 to December 2012,116 patients underwent catheter ablation of persistent AF in our department and were enrolled in this study. CHA2DS2VASc score was calculated as follows: two points were assigned for a history of stroke or transient ischemic attack and age ≥ 75 and 1 point each was assigned for age ≥ 65, a history of hypertension, diabetes,recent cardiac failure, vessel disease, female. Left atrial geometry ( LA) was reconstructed with a 3.5 mm tip ablation catheter with fill-in threshold 10 in CARTO system. The mapping catheter was stabled at each endocardial location for at least 3 seconds for recording. The electrogram recordings at each endocardial location were analyzed with a custom software embedded in the CARTO mapping system. Interval confidence level (ICL) was used to characterize complex fractionated atrial electrograms (CFAEs) . As the default setting of the software, ICL more than or equal to 7 was considered sites with a highly repetitive CFAEs complex. CFAEs index was defined as the fraction of area of ICL more than or equal to 7 to the left atrial surface. The CFAEs index and outcome of catheter ablation among different CHA2DS2VASc groups were compared. Of the 116 patients, CHA2DS2VASc was 0 in 33 patients, 1 in 31 patients and ≥ 2 in 52 patients. Left atrial surface ((121.2 ± 18.9) cm2, (133.6 ± 23.8) cm2, (133.9 ± 16.1) cm2, P = 0.008), left atrial volume ((103.6 ± 24.8) ml, (118.3 ± 27.8) ml, (120.9 ± 20.9) ml, P = 0.005) and CFAEs index (44.6% ± 22.4%, 54.2% ± 22.2%, 58.7% ± 23.1%, P = 0.023) increased in proportion with increasing CHA2DS2VASc. ICLmax, ICLmin and CFAEs spatial distribution were similar among the three groups. During the mean follow-up of (13 ± 8) months, the recurrence rate were 36.4%, 35.5%, 55.8% among the three groups (P = 0.025). A high CHA2DS2VASc score is associated with extensive AF substrate and higher recurrence rate post catheter ablation of persistent AF.

Mef2c Regulates Transcription of the Extracellular Matrix Protein Cartilage Link Protein 1 in the Developing Murine Heart

PubMed Central

Phelps, Aimee L.; Ghatnekar, Angela V.; Barth, Jeremy L.; Norris, Russell A.; Wessels, Andy

2013-01-01

Cartilage Link Protein 1 (Crtl1) is an extracellular matrix (ECM) protein that stabilizes the interaction between hyaluronan and versican and is expressed in endocardial and endocardially-derived cells in the developing heart, including cells in the atrioventricular (AV) and outflow tract (OFT) cushions. Previous investigations into the transcriptional regulation of the Crtl1 gene have shown that Sox9 regulates Crtl1 expression in both cartilage and the AV valves. The cardiac transcription factor Mef2c is involved in the regulation of gene expression in cardiac and skeletal muscle cell lineages. In this study we have investigated the potential role of Mef2c in the regulation of ECM production in the endocardial and mesenchymal cell lineages of the developing heart. We demonstrate that the Crtl1 5′ flanking region contains two highly conserved Mef2 binding sites and that Mef2c is able to bind to these sites in vivo during cardiovascular development. Additionally, we show that Crtl1 transcription is dependent on Mef2c expression in fetal mitral valve interstitial cells (VICs). Combined, these findings highlight a new role for Mef2c in cardiac development and the regulation of cardiac extracellular matrix protein expression. PMID:23468913

Automatic segmentation of right ventricle on ultrasound images using sparse matrix transform and level set

NASA Astrophysics Data System (ADS)

Qin, Xulei; Cong, Zhibin; Halig, Luma V.; Fei, Baowei

2013-03-01

An automatic framework is proposed to segment right ventricle on ultrasound images. This method can automatically segment both epicardial and endocardial boundaries from a continuous echocardiography series by combining sparse matrix transform (SMT), a training model, and a localized region based level set. First, the sparse matrix transform extracts main motion regions of myocardium as eigenimages by analyzing statistical information of these images. Second, a training model of right ventricle is registered to the extracted eigenimages in order to automatically detect the main location of the right ventricle and the corresponding transform relationship between the training model and the SMT-extracted results in the series. Third, the training model is then adjusted as an adapted initialization for the segmentation of each image in the series. Finally, based on the adapted initializations, a localized region based level set algorithm is applied to segment both epicardial and endocardial boundaries of the right ventricle from the whole series. Experimental results from real subject data validated the performance of the proposed framework in segmenting right ventricle from echocardiography. The mean Dice scores for both epicardial and endocardial boundaries are 89.1%+/-2.3% and 83.6+/-7.3%, respectively. The automatic segmentation method based on sparse matrix transform and level set can provide a useful tool for quantitative cardiac imaging.

Involvement of cyclooxygenase-2 in carbachol-induced positive inotropic response in mouse isolated left atrium.

PubMed

Hara, Yukio; Ike, Asako; Tanida, Riyo; Okada, Muneyoshi; Yamawaki, Hideyuki

2009-12-01

The mouse heart is expected to have characteristic contractile properties. However, basic information on the function of the mouse heart has not been accumulated sufficiently. In this study, the involvement of cyclooxygenase (COX)-2 in carbachol (CCh)-induced inotropic response was investigated in mouse isolated left atrium. Influences of CCh and their mechanisms of action on developed tension elicited by electrical stimulation were examined pharmacologically. The presence of COX-2 in atrium was examined by Western blotting and immunohistochemical analysis. CCh (3 microM for 15 min) produced a biphasic inotropic response: a transient decrease in contractile force followed by a late increase. Atropine suppressed the biphasic inotropic response to CCh. A muscarinic M(3) receptor antagonist, 4-diphenyl-acetoxy-N-methlpiperidine, inhibited the late positive inotropic action. Blockade of prostaglandin (PG) E(2) or F(2alpha) receptor by 6-isopropoxy-9-oxoxanthene-2-carboxylic acid (AH6809) or 9alpha, 15R-dihydroxy-11beta-fluoro-15-(2,3-dihydro-1H-inden-2-yl)-16,17,18,19,20-pentanor-prosta 5Z, 13E-dien-1-oic acid (AL8810), respectively, significantly suppressed the positive inotropic response to CCh. A nonselective COX inhibitor, indomethacin, and a selective COX-2 inhibitor, N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (NS-398) inhibited the positive response. A COX-1 inhibitor, valeroyl salicylate, did not affect the positive response. The positive response was almost completely abolished in the endocardial endothelium-deprived atria. Existence of COX-2 in endocardial endothelium was confirmed by Western blotting and immunohistochemical analysis. The present study indicated that the CCh-induced positive inotropic response was mediated by PGs, possibly PGE(2) and PGF(2alpha), released in part from endocardial endothelium. Furthermore, for the first time, we demonstrated that the production of PGs depended in part on COX-2 in endocardial endothelium through the muscarinic M(3) receptor stimulation.

Fatal Lyme carditis and endodermal heterotopia of the atrioventricular node.

PubMed Central

Cary, N. R.; Fox, B.; Wright, D. J.; Cutler, S. J.; Shapiro, L. M.; Grace, A. A.

1990-01-01

A fatal case of Lyme carditis occurring in a Suffolk farmworker is reported. Post-mortem examination of the heart showed pericarditis, focal myocarditis and prominent endocardial and interstitial fibrosis. The additional finding of endodermal heterotopia ('mesothelioma') of the atrioventricular node raises the possibility that this could also be related to Lyme infection and account for the relatively frequent occurrence of atrioventricular block in this condition. Lyme disease should always be considered in a case of atrioventricular block, particularly in a young patient from a rural area. The heart block tends to improve and therefore only temporary pacing may be required. Images Figure 1 Figure 2 Figure 3 PMID:2349186

Percutaneous fiber optic angioscopy of the left ventricle in patients with rheumatic valvular disease

NASA Astrophysics Data System (ADS)

Hirose, Junichi; Oshima, Tomomitsu; Fujimori, Yoshiharu; Uchida, Yasumi

1993-05-01

Recent advances in fiberoptic technology enabled us to observe percutaneously the cardiac chambers and valves. We examined left ventricular luminal and valvular changes by percutaneous fiberoptic angioscopy in patients with rheumatic valvular disease. Six patients with echocardiographic rheumatic changes in the mitral valves, underwent angioscopy during routine cardiac catheterization. The fiberscope 4.2 F in diameter, and the guiding catheter 9 F in external diameter with an inflatable balloon around the distal most tip were used for angioscopy. The left ventricular endocardial surface was diffusely white in color or white and brown in mosaic fashion. Echocardiography and angiography had low sensitivity for detecting the changes of the left ventricular luminal surface. Whitish changes which were observed by angioscopy were not related to the indices derived from echocardiography and angiography. The results indicate the possibility of percutaneous angioscopy in detecting left ventricular luminal changes in patients with rheumatic valvular disease.

Endocardial cushion defect

MedlinePlus

... Philadelphia, PA: Elsevier; 2016:chap 426. Kouchoukos NT, Blackstone EH, Hanley FL, Kirklin JK. Atrioventricular septal defect. In: Kouchoukos NT, Blackstone EH, Hanley FL, Kirklin JK, eds. Kirklin/Barratt- ...

Left ventricular approach for recording His bundle potential in man.

PubMed

Lee, Y S; Lien, W P

1975-06-01

The electrical potentials of the His bundle (HB) were recorded from the left ventricular endocardial surface in 28 patients ranging from 16 to 63 years of age. In 14 of the patients the left bundle branch (LB) potentials were also obtained. Placement of a bipolar electrode catheter tip toward the interventricular septum, right at and also 1 to 2 cm below the aortic valve, resulted in stable recordings of both potentials in successive cardiac cycles even at performing atrial or HB pacing from the right heart. The following intervals were measured in milliseconds (msec): P-A, A-H, H, H-V, LB, and LB-V. The average values in 12 patients (average age 26 plus or minus 7 years and average heart rate 90 plus or minus 16 beats per minute) with normal A-V conduction were as follows: P-A 28 plus or minus 7, A-H 76 plus or minus 16, H 19 plus or minus 3 and H-V 45 plus or minus 6 msec. The average values for LB and LB-V in 10 of these 12 patients were 15 plus or minus 3 and 25 plus or minus 3 msec respectively. Validation of the His bundle electrogram (HBE) from the left ventricular endocardial surface was based on simultaneous recordings of the intracardiac electrograms from both left and right sides of the heart in 18 patients. The individual average values for the intervals obtained from both sides of the heart in these patients were statistically not different, except that the H potential was slightly longer in duration fr m the left heart (P equals 0.05). Among these, 16 showed simultaneous onset of the H potentials, and the LB-V and RB-V conduction times from comparable points were almost the same. Indications for the left sided electro-physiologic studies include the following situations: (a) inability to record H from the right of the heart; (b) giant right atrium; and (c) possibly during atrial fibrillation.

Postmortem analysis of encapsulation around long-term ventricular endocardial pacing leads.

PubMed

Candinas, R; Duru, F; Schneider, J; Lüscher, T F; Stokes, K

1999-02-01

To analyze the site and thickness of encapsulation around ventricular endocardial pacing leads and the extent of tricuspid valve adhesion, from today's perspective, with implications for lead removal and sensor location. Gross cardiac postmortem analysis was performed in 11 cases (8 female and 3 male patients; mean age, 78+/-7 years). None of the patients had died because of pacemaker malfunction. The mean implant time was 61+/-60 months (range, 4 to 184). The observations ranged from encapsulation only at the tip of the pacing lead to complete encapsulation along the entire length of the pacing lead within the right ventricle. Substantial areas of adhesion at the tricuspid valve apparatus were noted in 7 of the 11 cases (64%). The firmly attached leads could be removed only by dissection, and in some cases, removal was possible only by damaging the associated structures. No specific optimal site for sensor placement could be identified along the ventricular portion of the pacing leads; however, the fibrotic response was relatively less prominent in the atrial chamber. Extensive encapsulation is present in most long-term pacemaker leads, which may complicate lead removal. The site and thickness of encapsulation seem to be highly variable. Tricuspid valve adhesion, which is usually underestimated, may be severe. In contrast to earlier reports, our study demonstrates that the extent of fibrotic encapsulation may not be related to the duration since lead implantation. Moreover, we noted no ideal encapsulation-free site for sensors on the ventricular portion of long-term pacing leads.

Electrophysiological determinants of hypokalaemia-induced arrhythmogenicity in the guinea-pig heart.

PubMed

Osadchii, O E; Olesen, S P

2009-12-01

Hypokalaemia is an independent risk factor contributing to arrhythmic death in cardiac patients. In the present study, we explored the mechanisms of hypokalaemia-induced tachyarrhythmias by measuring ventricular refractoriness, spatial repolarization gradients, and ventricular conduction time in isolated, perfused guinea-pig heart preparations. Epicardial and endocardial monophasic action potentials from distinct left ventricular (LV) and right ventricular (RV) recording sites were monitored simultaneously with volume-conducted electrocardiogram (ECG) during steady-state pacing and following a premature extrastimulus application at progressively reducing coupling stimulation intervals in normokalaemic and hypokalaemic conditions. Hypokalaemic perfusion (2.5 mm K(+) for 30 min) markedly increased the inducibility of tachyarrhythmias by programmed ventricular stimulation and rapid pacing, prolonged ventricular repolarization and shortened LV epicardial and endocardial effective refractory periods, thereby increasing the critical interval for LV re-excitation. Hypokalaemia increased the RV-to-LV transepicardial repolarization gradients but had no effect on transmural dispersion of APD(90) and refractoriness across the LV wall. As determined by local activation time recordings, the LV-to-RV transepicardial conduction and the LV transmural (epicardial-to-endocardial) conduction were slowed in hypokalaemic heart preparations. This change was attributed to depressed diastolic excitability as evidenced by increased ventricular pacing thresholds. These findings suggest that hypokalaemia-induced arrhythmogenicity is attributed to shortened LV refractoriness, increased critical intervals for LV re-excitation, amplified RV-to-LV transepicardial repolarization gradients and slowed ventricular conduction in the guinea-pig heart.

Histone deacetylase is required for the activation of Wnt/β-catenin signaling crucial for heart valve formation in zebrafish embryos.

PubMed

Kim, Young-Seop; Kim, Myoung-Jin; Koo, Tae-Hee; Kim, Jun-Dae; Koun, Soonil; Ham, Hyung Jin; Lee, You Mie; Rhee, Myungchull; Yeo, Sang-Yeob; Huh, Tae-Lin

2012-06-22

During vertebrate heart valve formation, Wnt/β-catenin signaling induces BMP signals in atrioventricular canal (AVC) myocardial cells and underlying AVC endocardial cells then undergo endothelial-mesenchymal transdifferentiation (EMT) by receiving this BMP signals. Histone deacetylases (HDACs) have been implicated in numerous developmental processes by regulating gene expression. However, their specific roles in controlling heart valve development are largely unexplored. To investigate the role of HDACs in vertebrate heart valve formation, we treated zebrafish embryos with trichostatin A (TSA), an inhibitor of class I and II HDACs, from 36 to 48 h post-fertilization (hpf) during which heart looping and valve formation occur. Following TSA treatment, abnormal linear heart tube development was observed. In these embryos, expression of AVC myocardial bmp4 and AVC endocardial notch1b genes was markedly reduced with subsequent failure of EMT in the AVC endocardial cells. However, LiCl-mediated activation of Wnt/β-catenin signaling was able to rescue defective heart tube formation, bmp4 and notch1b expression, and EMT in the AVC region. Taken together, our results demonstrated that HDAC activity plays a pivotal role in vertebrate heart tube formation by activating Wnt/β-catenin signaling which induces bmp4 expression in AVC myocardial cells. Copyright © 2012 Elsevier Inc. All rights reserved.

Current topics in surgery for multiple ventricular septal defects.

PubMed

Yoshimura, Naoki; Fukahara, Kazuaki; Yamashita, Akio; Doki, Yoshinori; Takeuchi, Katsunori; Higuma, Tomonori; Senda, Kazutaka; Toge, Masayoshi; Matsuo, Tatsuro; Nagura, Saori; Aoki, Masaya; Sakata, Kimimasa; Sakai, Mari

2016-04-01

In this review article, we describe several topics, including the sandwich technique, the transatrial re-endocardialization technique, the limited apical left ventriculotomy approach and device closure. The sandwich technique was introduced for the closure of muscular ventricular septal defects (VSD) by sandwiching the septum between two felt patches placed in the left and right ventricle. This technique requires neither the transection of muscular trabeculae nor ventriculotomy. Although the sandwich technique has resulted in the improvement of surgical outcomes, cases of postoperative cardiac dysfunction have been reported. Multiple smaller VSDs have been closed with transatrial re-endocardialization. Septal dysfunction may be avoided through this technique, in which the septal trabeculae are approximated in two layers of superficial, endocardial running sutures. Recently, a number of reports have recommended a limited apical left ventriculotomy approach. With this technique, a much shorter incision of around 1 cm at the apex of the left ventricle may be sufficient for achieving the complete closure of apical muscular VSDs. The transcatheter or perventricular device closure of muscular VSDs has increasingly been performed with good results. Although favorable early and mid-term results of device closure have been reported, this method is not always safer or less invasive than surgical closure. Long-term evaluations should be performed to determine whether the right and left ventricular functions are affected by treatment with relatively large devices in the heart.

A Novel Microwave Catheter Can Perform Noncontact Circumferential Endocardial Ablation in a Model of Pulmonary Vein Isolation.

PubMed

Qian, Pierre; Barry, Michael Anthony; Nguyen, Trang; Ross, David; Kovoor, Pramesh; McEwan, Alistair; Thomas, Stuart; Thiagalingam, Aravinda

2015-07-01

Pulmonary vein isolation is an effective treatment for atrial fibrillation. Current endocardial ablation techniques require catheter contact for lesion formation. Inadequate or inconsistent catheter contact results in difficulty with achieving acute and long-term isolation and consequent atrial arrhythmia recurrence. Microwave energy produces radiant heating and therefore can be used for noncontact catheter ablation. We hypothesized that it is possible to design a microwave catheter to produce a circumferential transmural thermal lesion in an in vitro model of a pulmonary vein antrum. A monopole microwave catheter with a sideways firing axially symmetrical heating pattern was designed. Noncontact ablations were performed in a perfused pulmonary vein model constructed from microwave myocardial phantom embedded with a sheet of thermochromic liquid crystal to permit visualization and measurement of thermal lesions from color changes. 1200 J ablations were performed at 150 W for 80 seconds and 120 W for 100 seconds at high (0.8 L/min) and low (0.06 L/min) flow through the modeled pulmonary vein. Myocardial tissue was substituted for the phantom material and ablations repeated at 150 W for 180 seconds and stained with nitro-blue tetrazolium. The catheter was able to induce deep circumferential antral lesions in myocardial phantom and myocardial tissue. Higher power and shorter ablations delivering the same amount of microwave energy resulted in larger lesions with less surface sparing. A microwave catheter can be designed to produce a circumferential thermal lesion on noncontact ablation and may have possible applications for pulmonary vein isolation. © 2015 Wiley Periodicals, Inc.

Regenerative responses after mild heart injuries for cardiomyocyte proliferation in zebrafish

PubMed Central

Itou, Junji; Akiyama, Ryutaro; Pehoski, Steve; Yu, Xiaodan; Kawakami, Hiroko; Kawakami, Yasuhiko

2014-01-01

Background The zebrafish heart regenerates after various severe injuries. Common processes of heart regeneration are cardiomyocyte proliferation, activation of epicardial tissue and neovascularization. In order to further characterize heart regeneration processes, we introduced milder injuries and compared responses to those induced by ventricular apex resection, a widely used injury method. We used scratching of the ventricular surface and puncturing of the ventricle with a fine tungsten needle as injury inducing techniques. Results Scratching the ventricular surface induced subtle cardiomyocyte proliferation and responses of the epicardium. Endothelial cell accumulation was limited to the surface of the heart. Ventricular puncture induced cardiomyocyte proliferation, endocardial and epicardial activation and neo-vascularization, similar to the resection method. However, the degree of the responses was milder, correlating with milder injury. Sham operation induced epicardial aldh1a2 expression but not tbx18 and WT1. Conclusions Puncturing the ventricle induces responses equivalent to resection at milder degrees in a shorter time frame and would be used as simple injury model. Scratching the ventricle did not induce heart regeneration and would be used for studying wound responses to epicardium. PMID:25074230

Transvenous right ventricular pacing in a patient with tricuspid mechanical prosthesis.

PubMed

Sierra, Juan; Rubio, José

2008-07-09

We report a patient in whom permanent endocardial pacing was accomplished by passage of the electrode through a mechanical tricuspid valve. Echocardiography study showed a minimal tricuspid regurgitation.

Evaluation of left ventricular function by bedside ultrasound in acute toxic myocarditis.

PubMed

Brown, Cara; Budhram, Gavin

2013-10-01

Myocarditis can be difficult to diagnose in the Emergency Department (ED) due to the lack of classic symptoms and the wide variation in presentations. Poor cardiac contractility is a common finding in myocarditis and can be evaluated by bedside ultrasound. To demonstrate the utility of fractional shortening measurements as an estimation of left ventricular function during bedside cardiac ultrasound evaluation in the ED. A 54-year-old man presented to the ED complaining of 3 days of chest tightness, palpitations, and dyspnea, as well as persistent abdominal pain and vomiting. An electrocardiogram (ECG) showed sinus tachycardia with presumably new ST-segment elevation and signs of an incomplete right bundle branch block. A bedside echocardiogram was performed by the emergency physician that showed poor left ventricular function by endocardial fractional shortening measurements. On further questioning, the patient revealed that for the past 2 weeks he had been regularly huffing a commercially available compressed air duster. Based on these history and examination findings, the patient was given a presumptive diagnosis of toxic myocarditis. A follow-up echocardiogram approximately 7 weeks later demonstrated resolution of the left ventricular systolic dysfunction and his ECG findings normalized. Cardiac ultrasound findings of severely reduced global function measured by endocardial fractional shortening were seen in this patient and supported the diagnosis of myocarditis. Endocardial fractional shortening is a useful means of easily evaluating and documenting left ventricular function and can be performed at the bedside in the ED. Copyright © 2013 Elsevier Inc. All rights reserved.

Comparison of treadmill exercise stress cardiac MRI to stress echocardiography in healthy volunteers for adequacy of left ventricular endocardial wall visualization: A pilot study

PubMed Central

Thavendiranathan, Paaladinesh; Dickerson, Jennifer A.; Scandling, Debbie; Balasubramanian, Vijay; Pennell, Michael L.; Hinton, Alice; Raman, Subha V.; Simonetti, Orlando P.

2013-01-01

Purpose To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in healthy volunteers with respect to adequacy of endocardial visualization and confidence of stress study interpretation. Materials and Methods 28 healthy volunteers (aged 28 ± 11 years, 15 males) underwent exercise stress echo and cardiac MR one week apart assigned randomly to one test first. Stress cardiac MR was performed using an MRI-compatible treadmill; stress echo was performed as per routine protocol. Cardiac MR and echo images were independently reviewed and scored for adequacy of endocardial visualization and confidence in interpretation of the stress study. Results Heart rate at the time of imaging was similar between the studies. Average time from cessation of exercise to start of imaging (21 vs. 31 seconds, p<0.001) and time to acquire stress images (20 vs. 51 seconds, p<0.001) was shorter for cardiac MR. The number of myocardial segments adequately visualized was significantly higher by cardiac MR at rest (99.8% versus 96.4%, p=0.002) and stress (99.8% versus 94.1%, p=0.001). The proportion of subjects in whom there was high confidence in the interpretation was higher for cardiac MR than echo (96% vs 60%, p=0.005). Conclusion Exercise stress cardiac MR to assess peak exercise wall motion is feasible and can be performed at least as rapidly as stress echo. PMID:24123562

Outcomes of cardiac pacing in adult patients after a Fontan operation.

PubMed

Egbe, Alexander C; Huntley, Geoffery D; Connolly, Heidi M; Ammash, Naser M; Deshmukh, Abhishek J; Khan, Arooj R; Said, Sameh M; Akintoye, Emmanuel; Warnes, Carole A; Kapa, Suraj

2017-12-01

Cardiac pacing can be challenging after a Fontan operation, and limited data exist regarding pacing in adult Fontan patients. The objectives of our study were to determine risk factors for pacing and occurrence of device-related complications (DRCs) and pacemaker reinterventions. We performed a retrospective review of Fontan patients from 1994 through 2014. We defined DRCs as lead failure, lead recall, cardiac perforation, lead thrombus/vegetation, or device-related infection, and cardiovascular adverse events (CAEs) as venous thrombosis, stroke, death, or heart transplant. Pacemaker reintervention was defined as lead failure or recall. Of 439 patients, 166 (38%) had pacemakers implanted (79 during childhood; 87, adulthood); 114 patients (69%) received epicardial leads initially, and 52 (31%), endocardial leads. Pacing was initially atrial in 52 patients (31%); ventricular, 30 (18%); or dual chamber, 84 (51%). There were 37 reinterventions (1.9% per year) and 48 DRCs (2.4% per year). Pacemaker implantation during childhood was a risk factor for DRCs (hazard ratio, 2.01 [CI, 1.22-5.63]; P = .03). There were 70 CAEs (venous thrombosis, 5; stroke, 11; transplant, 8; and death, 46), yielding a rate of 3.5% per year. DRCs, CAEs, and reintervention rates were comparable for patients with epicardial or endocardial leads. More than one-third of adult Fontan patients referred to Mayo Clinic had pacemaker implantation. Epicardial leads were associated with high rate of pacemaker reinterventions but similar DRC rates in comparison to endocardial leads. Copyright © 2017 Elsevier Inc. All rights reserved.

Myocardial multilayer strain does not provide additional value for detection of myocardial viability assessed by SPECT imaging over and beyond standard strain.

PubMed

Orloff, Elisabeth; Fournier, Pauline; Bouisset, Frédéric; Moine, Thomas; Cournot, Maxime; Elbaz, Meyer; Carrié, Didier; Galinier, Michel; Lairez, Olivier; Cognet, Thomas

2018-05-14

The aim of this study was to evaluate the value of multilayer strain analysis to the assessment of myocardial viability (MV) through the comparison of both speckle tracking echocardiography and single-photon emission computed tomography (SPECT) imaging. We also intended to determine which segmental longitudinal strain (LS) cutoff value would be optimal to discriminate viable myocardium. We included 47 patients (average age: 61 ± 11 years) referred to our cardiac imaging center for MV evaluation. All patients underwent transthoracic echocardiography with measures of LS, SPECT, and coronary angiography. In all, 799 segments were analyzed. We correlated myocardial tracer uptake by SPECT with sub-endocardial, sub-epicardial, and mid-segmental LS values with r = .514 P < .0001, r = .501 P < .0001, and r = .520 P < .0001, respectively. The measurements of each layer strain (sub-endocardial, sub-epicardial, and mid) had the same performance to predict MV viability as defined by SPECT with areas under curve of 0.819 [0.778-0.861, P < .0001], 0.809 [0.764-0.854, P < .0001], and 0.817 [0.773-0.860, P < .0001], respectively. The receiver-operating characteristic analysis yielded a cutoff value of -6.5% for mid-segmental LS with a sensitivity of 76% and specificity of 76% to predict segmental MV as defined by SPECT. Multilayer strain analysis does not evaluate MV with more accuracy than standard segmental LS analysis. © 2018 Wiley Periodicals, Inc.

Bmp2 and Notch cooperate to pattern the embryonic endocardium.

PubMed

Papoutsi, T; Luna-Zurita, L; Prados, B; Zaffran, S; de la Pompa, J L

2018-05-31

Signaling interactions between myocardium and endocardium pattern embryonic cardiac regions, instructing their development to fulfill specific functions in the mature heart. We show that ectopic Bmp2 expression in the mouse chamber myocardium changes the transcriptional signature of adjacent chamber endocardial cells into valve tissue, and enables them to undergo epithelial-mesenchyme transition. This induction is independent of valve myocardium specification and requires high levels of Notch1 activity. Biochemical experiments suggest that Bmp2-mediated Notch1 induction is achieved through transcriptional activation of the Notch ligand Jag1, and physical interaction of Smad1/5 with the intracellular domain of the Notch1 receptor. Thus, widespread myocardial Bmp2 and endocardial Notch signaling drive presumptive ventricular endocardium to differentiate into valve endocardium. Understanding the molecular basis of valve development is instrumental to designing therapeutic strategies for congenital heart valve defects. © 2018. Published by The Company of Biologists Ltd.

Evaluation of wireless stimulation of the endocardium, WiSE, technology for treatment heart failure.

PubMed

Seifert, M; Butter, C

2016-06-01

There are several unsolved limitations in delivering cardiac resynchronization therapy. 30-40% of patients fail to have any clinical benefit after 6 months caused by different reasons. Endocardial stimulation rather than conventional epicardial pacing has been shown to: be more physiologically, improve electrical stimulation of the left ventricular, give less dispersion of repolarisation and result in better resynchronization. The Wireless Cardiac Stimulation in Left Ventricle, WiCS-LV, system provides an option for wireless, left ventricular endocardial pacing triggered from a conventional right ventricular pacing spike from a co-implant. Expert commentary: The feasibility of the WiCS-LV system has been successfully demonstrated in a population of failed cardiac resynchronization patients, either failed implantation procedure of a conventional system, non-responder to conventional therapy or upgrade from pacemaker or defibrillator, where a conventional system was not an option. WiCS-LV is innovative technology with promising safety, performance and preliminary efficacy.

On the precision of automated activation time estimation

NASA Technical Reports Server (NTRS)

Kaplan, D. T.; Smith, J. M.; Rosenbaum, D. S.; Cohen, R. J.

1988-01-01

We examined how the assignment of local activation times in epicardial and endocardial electrograms is affected by sampling rate, ambient signal-to-noise ratio, and sinx/x waveform interpolation. Algorithms used for the estimation of fiducial point locations included dV/dtmax, and a matched filter detection algorithm. Test signals included epicardial and endocardial electrograms overlying both normal and infarcted regions of dog myocardium. Signal-to-noise levels were adjusted by combining known data sets with white noise "colored" to match the spectral characteristics of experimentally recorded noise. For typical signal-to-noise ratios and sampling rates, the template-matching algorithm provided the greatest precision in reproducibly estimating fiducial point location, and sinx/x interpolation allowed for an additional significant improvement. With few restrictions, combining these two techniques may allow for use of digitization rates below the Nyquist rate without significant loss of precision.

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

PubMed

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

2002-01-01

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

The ventricular intracardiac unipolar paced-evoked potential in an isolated animal heart.

PubMed

Economides, A P; Walton, C; Gergely, S

1988-02-01

The endocardial unipolar paced evoked response has excited a great deal of interest due to its possible use in the measurement of the metabolic state of the body and other pacer-related areas. Although rate-responsive pacing utilizing this signal has been clinically evaluated, little is known regarding the behavior of the components of this waveform under normal physiological conditions. We have developed an electronic circuit which allows the recording of the evoked response within a few milliseconds of a pacing stimulus of 5 V and 0.5 ms duration being applied using a single unipolar, smooth platinum electrode of 14 mm2 surface area. The paced evoked response was measured using a total of 20 isolated rabbit heart preparations. Five were run for 8 hours and the remaining fifteen were run for 5 hours. Our results indicate that the waveform components of the evoked response remain stable while the preparation is viable, but that two of the time-related measurements change with loss of viability. A significant lengthening of the stimulus-R interval was seen together with a dramatic shortening of the R-T period. The net result of these changes was an overall reduction of 17% in the complex duration. In addition, we found the R-T shortening to be a sensitive measure of myocardial integrity. We conclude that the combination of our interface charge elimination circuit and the isolated heart preparation has proved a useful system for the investigation of the paced evoked potential. Furthermore, the loss of myocardial viability has a complex action on this response.

Feasibility of high-resolution quantitative perfusion analysis in patients with heart failure.

PubMed

Sammut, Eva; Zarinabad, Niloufar; Wesolowski, Roman; Morton, Geraint; Chen, Zhong; Sohal, Manav; Carr-White, Gerry; Razavi, Reza; Chiribiri, Amedeo

2015-02-12

Cardiac magnetic resonance (CMR) is playing an expanding role in the assessment of patients with heart failure (HF). The assessment of myocardial perfusion status in HF can be challenging due to left ventricular (LV) remodelling and wall thinning, coexistent scar and respiratory artefacts. The aim of this study was to assess the feasibility of quantitative CMR myocardial perfusion analysis in patients with HF. A group of 58 patients with heart failure (HF; left ventricular ejection fraction, LVEF ≤ 50%) and 33 patients with normal LVEF (LVEF >50%), referred for suspected coronary artery disease, were studied. All subjects underwent quantitative first-pass stress perfusion imaging using adenosine according to standard acquisition protocols. The feasibility of quantitative perfusion analysis was then assessed using high-resolution, 3 T kt perfusion and voxel-wise Fermi deconvolution. 30/58 (52%) subjects in the HF group had underlying ischaemic aetiology. Perfusion abnormalities were seen amongst patients with ischaemic HF and patients with normal LV function. No regional perfusion defect was observed in the non-ischaemic HF group. Good agreement was found between visual and quantitative analysis across all groups. Absolute stress perfusion rate, myocardial perfusion reserve (MPR) and endocardial-epicardial MPR ratio identified areas with abnormal perfusion in the ischaemic HF group (p = 0.02; p = 0.04; p = 0.02, respectively). In the Normal LV group, MPR and endocardial-epicardial MPR ratio were able to distinguish between normal and abnormal segments (p = 0.04; p = 0.02 respectively). No significant differences of absolute stress perfusion rate or MPR were observed comparing visually normal segments amongst groups. Our results demonstrate the feasibility of high-resolution voxel-wise perfusion assessment in patients with HF.

Automatic segmentation of right ventricular ultrasound images using sparse matrix transform and a level set

NASA Astrophysics Data System (ADS)

Qin, Xulei; Cong, Zhibin; Fei, Baowei

2013-11-01

An automatic segmentation framework is proposed to segment the right ventricle (RV) in echocardiographic images. The method can automatically segment both epicardial and endocardial boundaries from a continuous echocardiography series by combining sparse matrix transform, a training model, and a localized region-based level set. First, the sparse matrix transform extracts main motion regions of the myocardium as eigen-images by analyzing the statistical information of the images. Second, an RV training model is registered to the eigen-images in order to locate the position of the RV. Third, the training model is adjusted and then serves as an optimized initialization for the segmentation of each image. Finally, based on the initializations, a localized, region-based level set algorithm is applied to segment both epicardial and endocardial boundaries in each echocardiograph. Three evaluation methods were used to validate the performance of the segmentation framework. The Dice coefficient measures the overall agreement between the manual and automatic segmentation. The absolute distance and the Hausdorff distance between the boundaries from manual and automatic segmentation were used to measure the accuracy of the segmentation. Ultrasound images of human subjects were used for validation. For the epicardial and endocardial boundaries, the Dice coefficients were 90.8 ± 1.7% and 87.3 ± 1.9%, the absolute distances were 2.0 ± 0.42 mm and 1.79 ± 0.45 mm, and the Hausdorff distances were 6.86 ± 1.71 mm and 7.02 ± 1.17 mm, respectively. The automatic segmentation method based on a sparse matrix transform and level set can provide a useful tool for quantitative cardiac imaging.

BIOPHYSICAL PARAMETERS DURING RADIOFREQUENCY CATHETER ABLATION OF SCAR-MEDIATED VENTRICULAR TACHYCARDIA: EPICARDIAL AND ENDOCARDIAL APPLICATIONS VIA MANUAL AND MAGNETIC NAVIGATION

PubMed Central

Bourke, Tara; Buch, Eric; Mathuria, Nilesh; Michowitz, Yoav; Yu, Ricky; Mandapati, Ravi; Shivkumar, Kalyanam; Tung, Roderick

2014-01-01

Background There is a paucity of data on biophysical parameters during radiofrequency ablation of scar-mediated ventricular tachycardia (VT). Methods and Results Data was collected from consecutive patients undergoing VT ablation with open-irrigation. Complete data was available for 372 lesions in 21 patients. The frequency of biophysical parameter changes were: >10Ω reduction (80%), bipolar EGM reduction (69%), while loss of capture was uncommon (32%). Unipolar injury current was seen in 72% of radiofrequency applications. Both EGM reduction and impedance drop were seen in 57% and a change in all 3 parameters was seen in only 20% of lesions. Late potentials were eliminated in 33%, reduced/modified in 56%, and remained after ablation in 11%. Epicardial lesions exhibited an impedance drop (90% vs 76%, p=0.002) and loss of capture (46% vs 27%, p<0.001) more frequently than endocardial lesions. Lesions delivered manually exhibited a >10Ω impedance drop (83% vs 71%, p=0.02) and an EGM reduction (71% vs 40%, p< 0.001) more frequently than lesions applied using magnetic navigation, although loss of capture, elimination of LPs, and a change in all 3 parameters were similarly observed. Conclusions VT ablation is inefficient as the majority of radiofrequency lesions do not achieve more than one targeted biophysical parameter. Only one-third of RF applications targeted at LPs result in complete elimination. Epicardial ablation within scar may be more effective than endocardial lesions and lesions applied manually may be more effective than lesions applied using magnetic navigation. New technologies directed at identifying and optimizing ablation effectiveness in scar are clinically warranted. PMID:24946895

Biophysical parameters during radiofrequency catheter ablation of scar-mediated ventricular tachycardia: epicardial and endocardial applications via manual and magnetic navigation.

PubMed

Bourke, Tara; Buch, Eric; Mathuria, Nilesh; Michowitz, Yoav; Yu, Ricky; Mandapati, Ravi; Shivkumar, Kalyanam; Tung, Roderick

2014-11-01

There is a paucity of data on biophysical parameters during radiofrequency ablation of scar-mediated ventricular tachycardia (VT). Data were collected from consecutive patients undergoing VT ablation with open-irrigation. Complete data were available for 372 lesions in 21 patients. The frequency of biophysical parameter changes were: >10Ω reduction (80%), bipolar EGM reduction (69%), while loss of capture was uncommon (32%). Unipolar injury current was seen in 72% of radiofrequency applications. Both EGM reduction and impedance drop were seen in 57% and a change in all 3 parameters was seen in only 20% of lesions. Late potentials were eliminated in 33%, reduced/modified in 56%, and remained after ablation in 11%. Epicardial lesions exhibited an impedance drop (90% vs. 76%, P = 0.002) and loss of capture (46% vs. 27%, P < 0.001) more frequently than endocardial lesions. Lesions delivered manually exhibited a >10Ω impedance drop (83% vs. 71%, P = 0.02) and an EGM reduction (71% vs. 40%, P < 0.001) more frequently than lesions applied using magnetic navigation, although loss of capture, elimination of LPs, and a change in all 3 parameters were similarly observed. VT ablation is inefficient as the majority of radiofrequency lesions do not achieve more than one targeted biophysical parameter. Only one-third of RF applications targeted at LPs result in complete elimination. Epicardial ablation within scar may be more effective than endocardial lesions, and lesions applied manually may be more effective than lesions applied using magnetic navigation. New technologies directed at identifying and optimizing ablation effectiveness in scar are clinically warranted. © 2014 Wiley Periodicals, Inc.

Left ventricular volume estimation in cardiac three-dimensional ultrasound: a semiautomatic border detection approach.

PubMed

van Stralen, Marijn; Bosch, Johan G; Voormolen, Marco M; van Burken, Gerard; Krenning, Boudewijn J; van Geuns, Robert-Jan M; Lancée, Charles T; de Jong, Nico; Reiber, Johan H C

2005-10-01

We propose a semiautomatic endocardial border detection method for three-dimensional (3D) time series of cardiac ultrasound (US) data based on pattern matching and dynamic programming, operating on two-dimensional (2D) slices of the 3D plus time data, for the estimation of full cycle left ventricular volume, with minimal user interaction. The presented method is generally applicable to 3D US data and evaluated on data acquired with the Fast Rotating Ultrasound (FRU-) Transducer, developed by Erasmus Medical Center (Rotterdam, the Netherlands), a conventional phased-array transducer, rotating at very high speed around its image axis. The detection is based on endocardial edge pattern matching using dynamic programming, which is constrained by a 3D plus time shape model. It is applied to an automatically selected subset of 2D images of the original data set, for typically 10 equidistant rotation angles and 16 cardiac phases (160 images). Initialization requires the drawing of four contours per patient manually. We evaluated this method on 14 patients against MRI end-diastole and end-systole volumes. Initialization requires the drawing of four contours per patient manually. We evaluated this method on 14 patients against MRI end-diastolic (ED) and end-systolic (ES) volumes. The semiautomatic border detection approach shows good correlations with MRI ED/ES volumes (r = 0.938) and low interobserver variability (y = 1.005x - 16.7, r = 0.943) over full-cycle volume estimations. It shows a high consistency in tracking the user-defined initial borders over space and time. We show that the ease of the acquisition using the FRU-transducer and the semiautomatic endocardial border detection method together can provide a way to quickly estimate the left ventricular volume over the full cardiac cycle using little user interaction.

Chemical ablation of the Purkinje system causes early termination and activation rate slowing of long-duration ventricular fibrillation in dogs.

PubMed

Dosdall, Derek J; Tabereaux, Paul B; Kim, Jong J; Walcott, Gregory P; Rogers, Jack M; Killingsworth, Cheryl R; Huang, Jian; Robertson, Peter G; Smith, William M; Ideker, Raymond E

2008-08-01

Endocardial mapping has suggested that Purkinje fibers may play a role in the maintenance of long-duration ventricular fibrillation (LDVF). To determine the influence of Purkinje fibers on LDVF, we chemically ablated the Purkinje system with Lugol solution and recorded endocardial and transmural activation during LDVF. Dog hearts were isolated and perfused, and the ventricular endocardium was exposed and treated with Lugol solution (n = 6) or normal Tyrode solution as a control (n = 6). The left anterior papillary muscle endocardium was mapped with a 504-electrode (21 x 24) plaque with electrodes spaced 1 mm apart. Transmural activation was recorded with a six-electrode plunge needle on each side of the plaque. Ventricular fibrillation (VF) was induced, and perfusion was halted. LDVF spontaneously terminated sooner in Lugol-ablated hearts than in control hearts (4.9 +/- 1.5 vs. 9.2 +/- 3.2 min, P = 0.01). After termination of VF, both the control and Lugol hearts were typically excitable, but only short episodes of VF could be reinduced. Endocardial activation rates were similar during the first 2 min of LDVF for Lugol-ablated and control hearts but were significantly slower in Lugol hearts by 3 min. In control hearts, the endocardium activated more rapidly than the epicardium after 4 min of LDVF with wave fronts propagating most often from the endocardium to epicardium. No difference in transmural activation rate or wave front direction was observed in Lugol hearts. Ablation of the subendocardium hastens VF spontaneous termination and alters VF activation sequences, suggesting that Purkinje fibers are important in the maintenance of LDVF.

Epicardially-derived Fibroblasts Preferentially Contribute to the Parietal Leaflets of the Atrioventricular Valves in the Murine Heart

PubMed Central

Wessels, Andy; van den Hoff, Maurice J. B.; Adamo, Richard F.; Phelps, Aimee L.; Lockhart, Marie M.; Sauls, Kimberly; Briggs, Laura E.; Norris, Russell A.; van Wijk, Bram; Perez-Pomares, Jose M.; Dettman, Robert W.; Burch, John B. E.

2012-01-01

The importance of the epicardium for myocardial and valvuloseptal development has been well established; perturbation of epicardial development results in cardiac abnormalities, including thinning of the ventricular myocardial wall and malformations of the atrioventricular valvuloseptal complex. To determine the spatiotemporal contribution of epicardially derived cells to the developing fibroblast population in the heart we have used a mWt1/IRES/GFP-Cre mouse to trace the fate of EPDCs from embryonic day (ED)10 until birth. EPDCs begin to populate the compact ventricular myocardium around ED12. The migration of epicardially-derived fibroblasts toward the interface between compact and trabecular myocardium is completed around ED14. Remarkably, epicardially-derived fibroblasts do not migrate into the trabecular myocardium until after ED17. Migration of EPDCs into the atrioventricular cushion mesenchyme commences around ED12. As development progresses, the number of EPDCs increases significantly, specifically in the leaflets which derive from the lateral atrioventricular cushions. In these developing leaflets the epicardially-derived fibroblasts eventually largely replace the endocardially-derived cells. Importantly, the contribution of EPDCs to the leaflets derived from the major AV cushions is very limited. The differential contribution of EPDCs to the various leaflets of the atrioventricular valves provides a new paradigm in valve development and could lead to new insights into the pathogenesis of abnormalities that preferentially affect individual components of this region of the heart. The notion that there is a significant difference in the contribution of epicardially and endocardially derived cells to the individual leaflets of the atrioventricular valves has also important pragmatic consequences for the use of endocardial and epicardial cre-mouse models in studies of heart development. PMID:22546693

Endocardial Hippo signaling regulates myocardial growth and cardiogenesis.

PubMed

Artap, Stanley; Manderfield, Lauren J; Smith, Cheryl L; Poleshko, Andrey; Aghajanian, Haig; See, Kelvin; Li, Li; Jain, Rajan; Epstein, Jonathan A

2018-08-01

The Hippo signaling pathway has been implicated in control of cell and organ size, proliferation, and endothelial-mesenchymal transformation. This pathway impacts upon two partially redundant transcription cofactors, Yap and Taz, that interact with other factors, including members of the Tead family, to affect expression of downstream genes. Yap and Taz have been shown to regulate, in a cell-autonomous manner, myocardial proliferation, myocardial hypertrophy, regenerative potential, and overall size of the heart. Here, we show that Yap and Taz also play an instructive, non-cell-autonomous role in the endocardium of the developing heart to regulate myocardial growth through release of the paracrine factor, neuregulin. Without endocardial Yap and Taz, myocardial growth is impaired causing early post-natal lethality. Thus, the Hippo signaling pathway regulates cell size via both cell-autonomous and non-cell-autonomous mechanisms. Furthermore, these data suggest that Hippo may regulate organ size via a sensing and paracrine function in endothelial cells. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Embryological origin of the endocardium and derived valve progenitor cells: from developmental biology to stem cell-based valve repair.

PubMed

Pucéat, Michel

2013-04-01

The cardiac valves are targets of both congenital and acquired diseases. The formation of valves during embryogenesis (i.e., valvulogenesis) originates from endocardial cells lining the myocardium. These cells undergo an endothelial-mesenchymal transition, proliferate and migrate within an extracellular matrix. This leads to the formation of bilateral cardiac cushions in both the atrioventricular canal and the outflow tract. The embryonic origin of both the endocardium and prospective valve cells is still elusive. Endocardial and myocardial lineages are segregated early during embryogenesis and such a cell fate decision can be recapitulated in vitro by embryonic stem cells (ESC). Besides genetically modified mice and ex vivo heart explants, ESCs provide a cellular model to study the early steps of valve development and might constitute a human therapeutic cell source for decellularized tissue-engineered valves. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction. Copyright © 2012 Elsevier B.V. All rights reserved.

Inadvertent positioning of pacemaker leads in the pericardium.

PubMed

Berenji, Kambeez; Nerheim, Pamela; Olshansky, Brian

2003-10-01

A patient had a dual chamber pacemaker with endocardial leads implanted chronically. The lead position on chest X ray and the ECG pattern indicated lead malposition, but a CT scan and transesophageal echocardiography were nondiagnostic. Venography indicated that both leads were in the mediastinal and pericardial space.

Redundant roles of Sox17 and Sox18 in early cardiovascular development of mouse embryos

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

Sakamoto, Youhei; Hara, Kenshiro; Kanai-Azuma, Masami

Sox7, -17 and -18 constitute the Sox subgroup F (SoxF) of HMG box transcription factor genes, which all are co-expressed in developing vascular endothelial cells in mice. Here we characterized cardiovascular phenotypes of Sox17/Sox18-double and Sox17-single null embryos during early-somite stages. Whole-mount PECAM staining demonstrated the aberrant heart looping, enlarged cardinal vein and mild defects in anterior dorsal aorta formation in Sox17 single-null embryos. The Sox17/Sox18 double-null embryos showed more severe defects in formation of anterior dorsal aorta and head/cervical microvasculature, and in some cases, aberrant differentiation of endocardial cells and defective fusion of the endocardial tube. However, the posteriormore » dorsal aorta and allantoic microvasculature was properly formed in all of the Sox17/Sox18 double-null embryos. The anomalies in both anterior dorsal aorta and head/cervical vasculature corresponded with the weak Sox7 expression sites. This suggests the region-specific redundant activities of three SoxF members along the anteroposterior axis of embryonic vascular network.« less

HB-EGF function in cardiac valve development requires interaction with heparan sulfate proteoglycans.

PubMed

Iwamoto, Ryo; Mine, Naoki; Kawaguchi, Taichiro; Minami, Seigo; Saeki, Kazuko; Mekada, Eisuke

2010-07-01

HB-EGF, a member of the EGF family of growth factors, plays an important role in cardiac valve development by suppressing mesenchymal cell proliferation. Here, we show that HB-EGF must interact with heparan sulfate proteoglycans (HSPGs) to properly function in this process. In developing valves, HB-EGF is synthesized in endocardial cells but accumulates in the mesenchyme by interacting with HSPGs. Disrupting the interaction between HB-EGF and HSPGs in an ex vivo model of endocardial cushion explants resulted in increased mesenchymal cell proliferation. Moreover, homozygous knock-in mice (HB(Delta)(hb/)(Delta)(hb)) expressing a mutant HB-EGF that cannot bind to HSPGs developed enlarged cardiac valves with hyperproliferation of mesenchymal cells; this resulted in a phenotype that resembled that of Hbegf-null mice. Interestingly, although Hbegf-null mice had abnormal heart chambers and lung alveoli, HB(Delta)(hb/)(Delta)(hb) mice did not exhibit these defects. These results indicate that interactions with HSPGs are essential for the function of HB-EGF, especially in cardiac valve development, in which HB-EGF suppresses mesenchymal cell proliferation.

Retrospective study of congenital heart defects in 151 dogs.

PubMed

Tidholm, A

1997-03-01

The case records of 151 dogs diagnosed with congenital heart disease were reviewed retrospectively. The most common defect was aortic stenosis, accounting for 35 per cent of all cases, followed by pulmonic stenosis (20 per cent), ventricular septal defect (12 per cent), patent ductus arteriosus (11 per cent), mitral valve dysplasia (8 per cent), tricuspid valve dysplasia (7 per cent), endocardial fibroelastosis (1.9 per cent) and tetralogy of Fallot (0.6 per cent). Fifty-one breeds were represented, with golden retrievers, German shepherd dogs and boxers predominating. No overall sex predilection was obvious. Seventy-five per cent of the dogs were asymptomatic at presentation. The defects most often associated with presenting symptoms, such as dyspnoea, syncope, ascites, failure to grow and depression, were mitral valve dysplasia, atrial septal defect, tricuspid valve dysplasia and endocardial fibroelastosis. The latter presented with the most severe signs of heart failure. In some cases of aortic stenosis and pulmonic stenosis, where the defect could not be accurately visualised with two-dimensional echocardiography, Doppler echocardiographic examination was needed for definitive diagnosis.

Right diaphragmatic paralysis following endocardial cryothermal ablation of inappropriate sinus tachycardia.

PubMed

Vatasescu, Radu; Shalganov, Tchavdar; Kardos, Attila; Jalabadze, Khatuna; Paprika, Dora; Gyorgy, Margit; Szili-Torok, Tamas

2006-10-01

Inappropriate sinus tachycardia (IST) is a rare disorder amenable to catheter ablation when refractory to medical therapy. Radiofrequency (RF) catheter modification/ablation of the sinus node (SN) is the usual approach, although it can be complicated by right phrenic nerve paralysis. We describe a patient with IST, who had symptomatic recurrences despite previous acutely successful RF SN modifications, including the use of electroanatomical mapping/navigation system. We decided to try transvenous cryothermal modification of the SN. We used 2 min applications at -85 degrees C at sites of the earliest atrial activation guided by activation mapping during isoprenaline infusion. Every application was preceded by high output stimulation to reveal phrenic nerve proximity. During the last application, heart rate slowly and persistently fell below 85 bpm despite isoprenaline infusion, but right diaphragmatic paralysis developed. At 6 months follow-up, the patient was asymptomatic and the diaphragmatic paralysis had partially resolved. This is the first report, we believe, of successful SN modification for IST by endocardial cryoablation, although this case also demonstrates the considerable risk of right phrenic nerve paralysis even with this ablation energy.

Feasibility of perflutren microsphere contrast transthoracic echocardiography in the visualization of ventricular endocardium during venovenous extracorporeal membrane oxygenation in a validated ovine model.

PubMed

Platts, David G; Diab, Sara; Dunster, Kimble R; Shekar, Kiran; Burstow, Darryl J; Sim, Beatrice; Tunbridge, Matthew; McDonald, Charles; Chemonges, Saul; Chan, Jonathan; Fraser, John F

2015-03-01

Transthoracic echocardiography (TTE) during extra corporeal membrane oxygenation (ECMO) is important but can be technically challenging. Contrast-specific TTE can improve imaging in suboptimal studies. These contrast microspheres are hydrodynamically labile structures. This study assessed the feasibility of contrast echocardiography (CE) during venovenous (VV) ECMO in a validated ovine model. Twenty-four sheep were commenced on VV ECMO. Parasternal long-axis (Plax) and short-axis (Psax) views were obtained pre- and postcontrast while on VV ECMO. Endocardial definition scores (EDS) per segment were graded: 1 = good, 2 = suboptimal 3 = not seen. Endocardial border definition score index (EBDSI) was calculated for each view. Endocardial length (EL) in the Plax view for the left ventricle (LV) and right ventricle (RV) was measured. Summation EDS data for the LV and RV for unenhanced TTE (UE) versus CE TTE imaging: EDS 1 = 289 versus 346, EDS 2 = 38 versus 10, EDS 3 = 33 versus 4, respectively. Wilcoxon matched-pairs rank-sign tests showed a significant ranking difference (improvement) pre- and postcontrast for the LV (P < 0.0001), RV (P < 0.0001) and combined ventricular data (P < 0.0001). EBDSI for CE TTE was significantly lower than UE TTE for the LV (1.05 ± 0.17 vs. 1.22 ± 0.38, P = 0.0004) and RV (1.06 ± 0.22 vs. 1.42 ± 0.47, P = 0.0.0006) respectively. Visualized EL was significantly longer in CE versus UE for both the LV (58.6 ± 11.0 mm vs. 47.4 ± 11.7 mm, P < 0.0001) and the RV (52.3 ± 8.6 mm vs. 36.0 ± 13.1 mm, P < 0.0001), respectively. Despite exposure to destructive hydrodynamic forces, CE is a feasible technique in an ovine ECMO model. CE results in significantly improved EDS and increased EL. © 2014, Wiley Periodicals, Inc.

Alterations in left ventricular curvature and principal strains in dilated cardiomyopathy with functional mitral regurgitation.

PubMed

Tibayan, Frederick A; Lai, David T M; Timek, Tomasz A; Dagum, Paul; Liang, David; Zasio, Mary K; Daughters, George T; Miller, D Craig; Ingels, Neil B

2003-05-01

Functional mitral regurgitation (FMR) is increasingly recognized as a left ventricular (LV) disease. Dilated cardiomyopathy (DCM) is commonly accompanied by FMR and reduction of LV torsion. Therapeutic targets for DCM include LV size reduction, altered LV shape, elimination of MR, and increasing LV torsion. It was hypothesized that, in addition to increasing LV size, DCM with FMR would alter normal LV shape and reduce and alter the direction of principal strains across the LV wall. This hypothesis was tested by measuring changes in epicardial and endocardial 2-D principal strains and regional radii of curvature accompanying tachycardia-induced cardiomyopathy in ovine hearts. Radio-opaque marker arrays were implanted into the left ventricle of eight sheep, including one subepicardial triangle and one subendocardial triangle in the anterior wall of the left ventricle. At one week postoperatively, biplane videofluoroscopy was used to determine marker dynamics. Rapid ventricular pacing was then instituted until FMR and signs of heart failure developed, and fluoroscopy was repeated. Circumferential LV radii of curvature were determined from marker triplets. DCM changed the normal epicardial oval LV cross-section to a more circular configuration. The endocardium maintained its normal circular shape as the left ventricle dilated. Deformations of the triangles from end-diastole to end-systole were determined, and the magnitude and direction of 2-D principal strains calculated. DCM was associated with decreased magnitude of both epicardial (-0.095 +/- 0.055 versus -0.040 +/- 0.032, p = 0.006) and endocardial (-0.117 +/- 0.047 versus -0.073 +/- 0.037, p = 0.023) principal strains. DCM reduced the angle of epicardial but not endocardial principal strain. DCM with FMR is associated with LV dilation, circularization of the normally oval equatorial circumferential LV epicardium, transmural reduction in principal strain, and decrease in angle of principal epicardial strain. These changes contribute to a reduction in the net torsional moment and may guide the development of reverse remodeling procedures for the dilated, failing ventricle with FMR.

Arrhythmogenic Mechanisms in a Mouse Model of Catecholaminergic Polymorphic Ventricular Tachycardia

PubMed Central

Cerrone, Marina; Noujaim, Sami F.; Tolkacheva, Elena G.; Talkachou, Arkadzi; O’Connell, Ryan; Berenfeld, Omer; Anumonwo, Justus; Pandit, Sandeep V.; Vikstrom, Karen; Napolitano, Carlo; Priori, Silvia G.; Jalife, José

2008-01-01

Catecholaminergic polymorphic ventricular tachycardia (VT) is a lethal familial disease characterized by bidirectional VT, polymorphic VT, and ventricular fibrillation. Catecholaminergic polymorphic VT is caused by enhanced Ca2+ release through defective ryanodine receptor (RyR2) channels. We used epicardial and endocardial optical mapping, chemical subendocardial ablation with Lugol’s solution, and patch clamping in a knockin (RyR2/RyR2R4496C) mouse model to investigate the arrhythmogenic mechanisms in catecholaminergic polymorphic VT. In isolated hearts, spontaneous ventricular arrhythmias occurred in 54% of 13 RyR2/RyR2R4496C and in 9% of 11 wild-type (P=0.03) littermates perfused with Ca2+ and isoproterenol; 66% of 12 RyR2/RyR2R4496C and 20% of 10 wild-type hearts perfused with caffeine and epinephrine showed arrhythmias (P=0.04). Epicardial mapping showed that monomorphic VT, bidirectional VT, and polymorphic VT manifested as concentric epicardial breakthrough patterns, suggesting a focal origin in the His–Purkinje networks of either or both ventricles. Monomorphic VT was clearly unifocal, whereas bidirectional VT was bifocal. Polymorphic VT was initially multifocal but eventually became reentrant and degenerated into ventricular fibrillation. Endocardial mapping confirmed the Purkinje fiber origin of the focal arrhythmias. Chemical ablation of the right ventricular endocardial cavity with Lugol’s solution induced complete right bundle branch block and converted the bidirectional VT into monomorphic VT in 4 anesthetized RyR2/RyR2R4496C mice. Under current clamp, single Purkinje cells from RyR2/RyR2R4496C mouse hearts generated delayed afterdepolarization–induced triggered activity at lower frequencies and level of adrenergic stimulation than wild-type. Overall, the data demonstrate that the His–Purkinje system is an important source of focal arrhythmias in catecholaminergic polymorphic VT. PMID:17872467

Stroke or transient ischemic attack in patients with transvenous pacemaker or defibrillator and echocardiographically detected patent foramen ovale.

PubMed

DeSimone, Christopher V; Friedman, Paul A; Noheria, Amit; Patel, Nikhil A; DeSimone, Daniel C; Bdeir, Sami; Aakre, Christopher A; Vaidya, Vaibhav R; Slusser, Joshua P; Hodge, David O; Ackerman, Michael J; Rabinstein, Alejandro A; Asirvatham, Samuel J

2013-09-24

A patent foramen ovale (PFO) may permit arterial embolization of thrombi that accumulate on the leads of cardiac implantable electronic devices in the right-sided cardiac chambers. We sought to determine whether a PFO increases the risk of stroke/transient ischemic attack (TIA) in patients with endocardial leads. We retrospectively evaluated all patients who had endocardial leads implanted between January 1, 2000, and October 25, 2010, at Mayo Clinic Rochester. Echocardiography was used to establish definite PFO and non-PFO cohorts. The primary end point of stroke/TIA consistent with a cardioembolic etiology and the secondary end point of mortality during postimplantation follow-up were compared in PFO versus non-PFO patients with the use of Cox proportional hazards models. We analyzed 6075 patients (364 with PFO) followed for a mean 4.7 ± 3.1 years. The primary end point of stroke/TIA was met in 30/364 (8.2%) PFO versus 117/5711 (2.0%) non-PFO patients (hazard ratio, 3.49; 95% confidence interval, 2.33-5.25; P<0.0001). The association of PFO with stroke/TIA remained significant after multivariable adjustment for age, sex, history of stroke/TIA, atrial fibrillation, and baseline aspirin/warfarin use (hazard ratio, 3.30; 95% confidence interval, 2.19-4.96; P<0.0001). There was no significant difference in all-cause mortality between PFO and non-PFO patients (hazard ratio, 0.91; 95% confidence interval, 0.77-1.07; P=0.25). In patients with endocardial leads, the presence of a PFO on routine echocardiography is associated with a substantially increased risk of embolic stroke/TIA. This finding suggests a role of screening for PFOs in patients who require cardiac implantable electronic devices; if a PFO is detected, PFO closure, anticoagulation, or nonvascular lead placement may be considered.

Left ventricular endocardial surface detection based on real-time 3D echocardiographic data

NASA Technical Reports Server (NTRS)

Corsi, C.; Borsari, M.; Consegnati, F.; Sarti, A.; Lamberti, C.; Travaglini, A.; Shiota, T.; Thomas, J. D.

2001-01-01

OBJECTIVE: A new computerized semi-automatic method for left ventricular (LV) chamber segmentation is presented. METHODS: The LV is imaged by real-time three-dimensional echocardiography (RT3DE). The surface detection model, based on level set techniques, is applied to RT3DE data for image analysis. The modified level set partial differential equation we use is solved by applying numerical methods for conservation laws. The initial conditions are manually established on some slices of the entire volume. The solution obtained for each slice is a contour line corresponding with the boundary between LV cavity and LV endocardium. RESULTS: The mathematical model has been applied to sequences of frames of human hearts (volume range: 34-109 ml) imaged by 2D and reconstructed off-line and RT3DE data. Volume estimation obtained by this new semi-automatic method shows an excellent correlation with those obtained by manual tracing (r = 0.992). Dynamic change of LV volume during the cardiac cycle is also obtained. CONCLUSION: The volume estimation method is accurate; edge based segmentation, image completion and volume reconstruction can be accomplished. The visualization technique also allows to navigate into the reconstructed volume and to display any section of the volume.

Computational Modeling of Open-Irrigated Electrodes for Radiofrequency Cardiac Ablation Including Blood Motion-Saline Flow Interaction

PubMed Central

González-Suárez, Ana; Berjano, Enrique; Guerra, Jose M.; Gerardo-Giorda, Luca

2016-01-01

Radiofrequency catheter ablation (RFCA) is a routine treatment for cardiac arrhythmias. During RFCA, the electrode-tissue interface temperature should be kept below 80°C to avoid thrombus formation. Open-irrigated electrodes facilitate power delivery while keeping low temperatures around the catheter. No computational model of an open-irrigated electrode in endocardial RFCA accounting for both the saline irrigation flow and the blood motion in the cardiac chamber has been proposed yet. We present the first computational model including both effects at once. The model has been validated against existing experimental results. Computational results showed that the surface lesion width and blood temperature are affected by both the electrode design and the irrigation flow rate. Smaller surface lesion widths and blood temperatures are obtained with higher irrigation flow rate, while the lesion depth is not affected by changing the irrigation flow rate. Larger lesions are obtained with increasing power and the electrode-tissue contact. Also, larger lesions are obtained when electrode is placed horizontally. Overall, the computational findings are in close agreement with previous experimental results providing an excellent tool for future catheter research. PMID:26938638

The value of the 12-lead electrocardiogram in localizing the scar in non-ischaemic cardiomyopathy.

PubMed

Oloriz, Teresa; Wellens, Hein J J; Santagostino, Giulia; Trevisi, Nicola; Silberbauer, John; Peretto, Giovanni; Maccabelli, Giuseppe; Della Bella, Paolo

2016-12-01

Patients with non-ischaemic cardiomyopathy (NICM) and ventricular tachycardia can be categorized as anteroseptal (AS) or inferolateral (IL) scar sub-types based on imaging and voltage mapping studies. The aim of this study was to correlate the baseline electrocardiogram (ECG) with endo-epicardial voltage maps created during ablation procedures and identify the ECG characteristics that may help to distinguish the scar as AS or IL. We assessed 108 baseline ECGs; 72 patients fulfilled criteria for dilated cardiomyopathy whereas 36 showed minimal structural abnormalities. Based on the unipolar low-voltage distribution, the scar pattern was classified as predominantly AS (n = 59) or IL (n = 49). Three ECG criteria (PR interval < 170 ms or QRS voltage in inferior leads <0.6 mV or a lateral q wave) resulted in 92% sensitivity and 90% specificity for predicting an IL pattern in patients with preserved ejection fraction (EF). The four-step algorithm for dilated cardiomyopathy included a paced ventricular rhythm or PR > 230 ms or QRS > 170 ms or an r ≤ 0.3 mV in V3 having 92 and 81% of sensitivity and specificity, respectively, in predicting AS scar pattern. A significant negative correlation was found between the extension of the endocardial unipolar low voltage area and left ventricular EF (r s = -0.719, P < 0.001). The extent of endocardial AS unipolar low voltage was correlated with PR interval and QRS duration (r s = 0.583 and r s = 0.680, P < 0.001, respectively) and the IL epicardial unipolar low voltage with the mean voltage of the limb leads (r s = -0.639, P < 0.001). Baseline ECG features are well correlated with the distribution of unipolar voltage abnormalities in NICM and may help to predict the location of scar in this population. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

A bronchogenic cyst of the right ventricular endocardium.

PubMed

Weinrich, Malte; Lausberg, Henning F; Pahl, Stefan; Schäfers, Hans-Joachim

2005-02-01

In a 73-year-old male patient with a history of prostate cancer, a right ventricular endoluminal tumor was diagnosed by echocardiography. An endocardial papillary fibroelastoma or myxoma appeared possible; a malignant tumor could not be ruled out. The tumor was resected using extracorporeal circulation and cardioplegic arrest. Histopathology study revealed a bronchogenic cyst with ciliated epithelium.

Permanent transvenous pacemaker implantation in an Ibizan hound cross with persistent atrial standstill

PubMed Central

MacAulay, Kevin

2002-01-01

An Ibizan hound cross was referred with a 1-year history of syncope and exercise intolerance. An electrocardiogram showed bradycardia and no P waves; atrial standstill was diagnosed. A permanent artificial endocardial pacemaker was implanted. The lead dislodged and was reimplanted into the right ventricular apex. Capture was once again achieved. PMID:12395764

New horizons for study of the cardiopulmonary and circulatory systems. [image reconstruction techniques

NASA Technical Reports Server (NTRS)

Wood, E. H.

1976-01-01

The paper discusses the development of computer-controlled three-dimensional reconstruction techniques designed to determine the dynamic changes in the true shape and dimensions of the epi- and endocardial surfaces of the heart, along with variable time base (stop-action to real-time) displays of the transmural distribution of the coronary microcirculation and the three-dimensional anatomy of the macrovasculature in all regions of the body throughout individual cardiac and/or respiratory cycles. A technique for reconstructing a cross section of the heart from multiplanar videoroentgenograms is outlined. The capability of high spatial and high temporal resolution scanning videodensitometry makes possible measurement of the appearance, mean transit and clearance of roentgen opaque substances in three-dimensional space through the myocardium with a degree of simultaneous anatomic and temporal resolution not obtainable by current isotope techniques. The distribution of a variety of selected chemical elements or biologic materials within a body portion can also be determined.

Prevalence and mechanism of tricuspid regurgitation following implantation of endocardial leads for pacemaker or cardioverter-defibrillator.

PubMed

Al-Mohaissen, Maha A; Chan, Kwan Leung

2012-03-01

Endocardial lead-induced tricuspid regurgitation has not been well recognized, either clinically or echocardiographically, and yet it is likely a preventable iatrogenic disease. In severe cases, it can lead to right ventricular failure and require tricuspid valve surgery. This complication will become increasingly important, because the numbers of permanent pacemakers and implantable cardioverter-defibrillators are expected to increase because of the aging population and the expanding capabilities of these devices. Published studies are largely retrospective, and serial studies to assess the time course of the development of tricuspid regurgitation are lacking. The mechanisms and severity of tricuspid regurgitation may not be well evaluated by two-dimensional echocardiography. Real-time three-dimensional echocardiography appears to be a promising technique to evaluate the mechanism of tricuspid regurgitation and may allow the early detection of patients who will develop severe lead-induced tricuspid regurgitation. A better understanding of the mechanism of lead-induced tricuspid regurgitation will be essential to the development of preventive strategies, which can then be tested in future clinical trials. Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

[Radioisotopic mapping of the arrhythmogenic focus in patients with chronic chagasic cardiomyopathy and sustained ventricular tachycardia].

PubMed

de Paola, A A; Balbão, C E; Castiglioni, M L; Barbieri, A; Mendonça, A; Netto, O S; Guiguer Júnior, N; Vattimo, A C; Souza, I A; Portugal, O P

1993-06-01

To localize the site of the origin of sustained ventricular tachycardia in chronic chagasic cardiomyopathy patients refractory to antiarrhythmic therapy by radionuclide angiography techniques. Five patients underwent radionuclide angiography by intravenous administration of 25mCi 99mTc. The images were obtained in sinus rhythm and during sustained ventricular tachycardia induced in the electrophysiologic laboratory for endocardial mapping. Amplitude and phase images were obtained resulting in a contraction wave synchronic to ventricular dispolarization. All patients had haemodynamic stability during the arrhythmia. One patient had incessant ventricular tachycardia. Mean ejection fraction was 0.38. In 4 patients the site of the origin of ventricular tachycardia was posterior and in one it was localized in the interventricular septum. There was identity in the site of the origin of ventricular tachycardia obtained by endocardial mapping or radionuclide angiography in all patients. The therapy was chemical ablation in 3 patients, surgical aneurysmectomy in one and pharmacologic therapy in the last patient. The site of the origin of ventricular tachycardia can be estimated by analyzing the contraction wave obtained by radionuclide angiography techniques in patients with hemodynamic stable sustained ventricular tachycardia.

Cell Migration During Heart Regeneration in Zebrafish

PubMed Central

Tahara, Naoyuki; Brush, Michael; Kawakami, Yasuhiko

2018-01-01

Zebrafish possess the remarkable ability to regenerate injured hearts as adults, which contrasts the very limited ability in mammals. Although very limited, mammalian hearts do in fact have measurable levels of cardiomyocyte regeneration. Therefore, elucidating mechanisms of zebrafish heart regeneration would provide information of naturally occurring regeneration to potentially apply to mammalian studies, in addition to addressing this biologically interesting phenomenon in itself. Studies over the past 13 years have identified processes and mechanisms of heart regeneration in zebrafish. After heart injury, preexisting cardiomyocytes dedifferentiate, enter the cell cycle, and repair the injured myocardium. This process requires interaction with epicardial cells, endocardial cells, and vascular endothelial cells. Epicardial cells envelope the heart, while endocardial cells make up the inner lining of the heart. They provide paracrine signals to cardiomyocytes to regenerate the injured myocardium, which is vascularized during heart regeneration. In addition, accumulating results suggest that local migration of these major cardiac cell types have roles in heart regeneration. In this review, we summarize the characteristics of various heart injury methods used in the research community and regeneration of the major cardiac cell types. Then, we discuss local migration of these cardiac cell types and immune cells during heart regeneration. PMID:27085002

Kingella kingae: Carriage, Transmission, and Disease

PubMed Central

2015-01-01

SUMMARY Kingella kingae is a common etiology of pediatric bacteremia and the leading agent of osteomyelitis and septic arthritis in children aged 6 to 36 months. This Gram-negative bacterium is carried asymptomatically in the oropharynx and disseminates by close interpersonal contact. The colonized epithelium is the source of bloodstream invasion and dissemination to distant sites, and certain clones show significant association with bacteremia, osteoarthritis, or endocarditis. Kingella kingae produces an RTX (repeat-in-toxin) toxin with broad-spectrum cytotoxicity that probably facilitates mucosal colonization and persistence of the organism in the bloodstream and deep body tissues. With the exception of patients with endocardial involvement, children with K. kingae diseases often show only mild symptoms and signs, necessitating clinical acumen. The isolation of K. kingae on routine solid media is suboptimal, and detection of the bacterium is significantly improved by inoculating exudates into blood culture bottles and the use of PCR-based assays. The organism is generally susceptible to antibiotics that are administered to young patients with joint and bone infections. β-Lactamase production is clonal, and the local prevalence of β-lactamase-producing strains is variable. If adequately and promptly treated, invasive K. kingae infections with no endocardial involvement usually run a benign clinical course. PMID:25567222

A comparison between Philips and Tomtec for left ventricular deformation and volume measurements in neonatal intensive care patients.

PubMed

de Waal, Koert; Phad, Nilkant

2018-03-01

Two-dimensional speckle tracking echocardiography is an emerging technique for analyzing cardiac function in newborns. Strain is a highly reliable and reproducible parameter, and reference values have been established for term and preterm newborns. Its implementation into clinical practice has been slow, partly due to lack of inter-vendor consistency. Our aim was to compare recent versions of Philips and Tomtec speckle tracking software for deformation and semiautomated volume and area measurements in neonatal intensive care patients. Longitudinal and circumferential deformation and cavity dimensions (volume, area) were determined off line from apical and short-axis images in 50 consecutive newborns with a median birthweight of 760 g (range 460-3200 g). Absolute mean endocardial global longitudinal strain measurements were similar between vendors, but with wide limits of agreement (Philips -18.9 [2.1]%, Tomtec -18.6 [2.5]%, bias -0.3 [1.7]%, and limits of agreement -3.6%-3.1%). Longitudinal strain rate and circumferential measurements showed poor correlation. All volume and area measurements correlated well between the vendors, but with significant bias. Global longitudinal strain measurements compared well between vendors but wide limits of agreement, suggesting that longitudinal measurements are preferred using similar hardware and software. © 2017, Wiley Periodicals, Inc.

Transmural ultrasound imaging of thermal lesion and action potential changes in perfused canine cardiac wedge preparations by high intensity focused ultrasound ablation.

PubMed

Wu, Ziqi; Gudur, Madhu S R; Deng, Cheri X

2013-01-01

Intra-procedural imaging is important for guiding cardiac arrhythmia ablation. It is difficult to obtain intra-procedural correlation of thermal lesion formation with action potential (AP) changes in the transmural plane during ablation. This study tested parametric ultrasound imaging for transmural imaging of lesion and AP changes in high intensity focused ultrasound (HIFU) ablation using coronary perfused canine ventricular wedge preparations (n = 13). The preparations were paced from epi/endocardial surfaces and subjected to HIFU application (3.5 MHz, 11 Hz pulse-repetition-frequency, 70% duty cycle, duration 4 s, 3500 W/cm(2)), during which simultaneous optical mapping (1 kframes/s) using di-4-ANEPPS and ultrasound imaging (30 MHz) of the same transmural surface of the wedge were performed. Spatiotemporally correlated AP measurements and ultrasound imaging allowed quantification of the reduction of AP amplitude (APA), shortening of AP duration at 50% repolarization, AP triangulation, decrease of optical AP rise, and change of conduction velocity along tissue depth direction within and surrounding HIFU lesions. The threshold of irreversible change in APA correlating to lesions was determined to be 43 ± 1% with a receiver operating characteristic (ROC) area under curve (AUC) of 0.96 ± 0.01 (n = 13). Ultrasound imaging parameters such as integrated backscatter, Rayleigh (α) and log-normal (σ) parameters, cumulative extrema of σ were tested, with the cumulative extrema of σ performing the best in detecting lesion (ROC AUC 0.89 ± 0.01, n = 13) and change of APA (ROC AUC 0.79 ± 0.03, n = 13). In conclusion, characteristic tissue and AP changes in HIFU ablation were identified and spatiotemporally correlated using optical mapping and ultrasound imaging. Parametric ultrasound imaging using cumulative extrema of σ can detect HIFU lesion and APA reduction.

Transmural Ultrasound Imaging of Thermal Lesion and Action Potential Changes in Perfused Canine Cardiac Wedge Preparations by High Intensity Focused Ultrasound Ablation

PubMed Central

Wu, Ziqi; Gudur, Madhu S. R.; Deng, Cheri X.

2013-01-01

Intra-procedural imaging is important for guiding cardiac arrhythmia ablation. It is difficult to obtain intra-procedural correlation of thermal lesion formation with action potential (AP) changes in the transmural plane during ablation. This study tested parametric ultrasound imaging for transmural imaging of lesion and AP changes in high intensity focused ultrasound (HIFU) ablation using coronary perfused canine ventricular wedge preparations (n = 13). The preparations were paced from epi/endocardial surfaces and subjected to HIFU application (3.5 MHz, 11 Hz pulse-repetition-frequency, 70% duty cycle, duration 4 s, 3500 W/cm2), during which simultaneous optical mapping (1 kframes/s) using di-4-ANEPPS and ultrasound imaging (30 MHz) of the same transmural surface of the wedge were performed. Spatiotemporally correlated AP measurements and ultrasound imaging allowed quantification of the reduction of AP amplitude (APA), shortening of AP duration at 50% repolarization, AP triangulation, decrease of optical AP rise, and change of conduction velocity along tissue depth direction within and surrounding HIFU lesions. The threshold of irreversible change in APA correlating to lesions was determined to be 43±1% with a receiver operating characteristic (ROC) area under curve (AUC) of 0.96±0.01 (n = 13). Ultrasound imaging parameters such as integrated backscatter, Rayleigh (α) and log-normal (σ) parameters, cumulative extrema of σ were tested, with the cumulative extrema of σ performing the best in detecting lesion (ROC AUC 0.89±0.01, n = 13) and change of APA (ROC AUC 0.79±0.03, n = 13). In conclusion, characteristic tissue and AP changes in HIFU ablation were identified and spatiotemporally correlated using optical mapping and ultrasound imaging. Parametric ultrasound imaging using cumulative extrema of σ can detect HIFU lesion and APA reduction. PMID:24349337

Simulating patient-specific heart shape and motion using SPECT perfusion images with the MCAT phantom

NASA Astrophysics Data System (ADS)

Faber, Tracy L.; Garcia, Ernest V.; Lalush, David S.; Segars, W. Paul; Tsui, Benjamin M.

2001-05-01

The spline-based Mathematical Cardiac Torso (MCAT) phantom is a realistic software simulation designed to simulate single photon emission computed tomographic (SPECT) data. It incorporates a heart model of known size and shape; thus, it is invaluable for measuring accuracy of acquisition, reconstruction, and post-processing routines. New functionality has been added by replacing the standard heart model with left ventricular (LV) epicaridal and endocardial surface points detected from actual patient SPECT perfusion studies. LV surfaces detected from standard post-processing quantitation programs are converted through interpolation in space and time into new B-spline models. Perfusion abnormalities are added to the model based on results of standard perfusion quantification. The new LV is translated and rotated to fit within existing atria and right ventricular models, which are scaled based on the size of the LV. Simulations were created for five different patients with myocardial infractions who had undergone SPECT perfusion imaging. Shape, size, and motion of the resulting activity map were compared visually to the original SPECT images. In all cases, size, shape and motion of simulated LVs matched well with the original images. Thus, realistic simulations with known physiologic and functional parameters can be created for evaluating efficacy of processing algorithms.

Left-ventricle segmentation in real-time 3D echocardiography using a hybrid active shape model and optimal graph search approach

NASA Astrophysics Data System (ADS)

Zhang, Honghai; Abiose, Ademola K.; Campbell, Dwayne N.; Sonka, Milan; Martins, James B.; Wahle, Andreas

2010-03-01

Quantitative analysis of the left ventricular shape and motion patterns associated with left ventricular mechanical dyssynchrony (LVMD) is essential for diagnosis and treatment planning in congestive heart failure. Real-time 3D echocardiography (RT3DE) used for LVMD analysis is frequently limited by heavy speckle noise or partially incomplete data, thus a segmentation method utilizing learned global shape knowledge is beneficial. In this study, the endocardial surface of the left ventricle (LV) is segmented using a hybrid approach combining active shape model (ASM) with optimal graph search. The latter is used to achieve landmark refinement in the ASM framework. Optimal graph search translates the 3D segmentation into the detection of a minimum-cost closed set in a graph and can produce a globally optimal result. Various information-gradient, intensity distributions, and regional-property terms-are used to define the costs for the graph search. The developed method was tested on 44 RT3DE datasets acquired from 26 LVMD patients. The segmentation accuracy was assessed by surface positioning error and volume overlap measured for the whole LV as well as 16 standard LV regions. The segmentation produced very good results that were not achievable using ASM or graph search alone.

Integrated multimodal-catheter imaging unveils principal relationships among ventricular electrical activity, anatomy, and function.

PubMed

Rao, Liyun; Ling, Yuesheng; He, Renjie; Gilbert, April L; Frangogiannis, Nikolaos G; Wang, Jianwen; Nagueh, Sherif F; Khoury, Dirar S

2008-02-01

Multiple imaging modalities are employed independent of one another while managing complex cardiac arrhythmias. To combine electrical, anatomical, and functional imaging in a single catheter system, we developed a balloon catheter that carried 64 electrodes on its surface and an intracardiac echocardiography (ICE) catheter through a central lumen. The catheter system was inserted, and the balloon was inflated inside the left ventricle (LV) of eight dogs with 6-wk-old infarction, created by occlusion in the left anterior descending coronary artery. Anatomy was constructed by ICE imaging (9 MHz) through the balloon. Single-beat noncontact mapping (NCM) was performed via the multielectrode array to reconstruct unipolar endocardial electrograms during sinus rhythm. Standard contact mapping (CM) of the endocardium was also carried out for reference. Myocardial infarction in anterior LV extending from the middle to apical regions was localized both by ICE and NCM and validated by CM and pathology. The overall difference in the activation times between NCM and CM was 3 +/- 1 ms. Unipolar voltage in infarcted middle anterior LV was smaller than the voltage in normal middle inferior LV both by NCM (11 +/- 4 vs. 16 +/- 3 mV; P = 0.002) and CM (11 +/- 3 vs. 20 +/- 4 mV; P < 0.001). Unipolar voltage was also inversely related to infarct transmurality, both by NCM (r = -0.87; P = 0.005) and CM (r = -0.94; P < 0.001). The infarct area by ICE (7.7 +/- 2.9 cm(2)) was in agreement with CM (bipolar voltage, <1 mV; and area, 7.6 +/- 3.3 cm(2); r = 0.80; P = 0.016). Meanwhile, the voltage threshold that depicted the infarct area by NCM was directly related to the smallest unipolar voltage reconstructed within the infarct (r = 0.96; P < 0.001). In conclusion, combining NCM and ICE imaging in a single catheter system is feasible. The preclinical development of such an integrated system and its evaluation in experimental myocardial infarction demonstrate capabilities for single-beat mapping at multiple sites as well as the online assessment of anatomy and myocardial function.

Heterogeneous memory in restitution of action potential duration in pig ventricles.

PubMed

Jing, Linyuan; Chourasia, Sonam; Patwardhan, Abhijit

2010-01-01

Restitution of action potential duration and memory importantly affect electrical stability in ventricles. Studies have reported heterogeneous restitution among different regions of the ventricles. However, existence of heterogeneity in memory is not as well investigated. Transmembrane potentials were recorded in endocardial and epicardial tissues from both ventricles of farm pigs. Pacing protocols with sinusoidally changing diastolic intervals were used to reveal hysteresis in restitution, from which quantitative measures of memory were calculated. Larger measures of hysteresis were observed in the endocardium than the epicardium (P < .05): loop thickness (in milliseconds), 26.9 vs 16.2; overall tilt, 0.376 vs 0.249; and loop area (in square milliseconds), 7288 vs 4146. Except for overall tilt, no significant differences in these measures were observed between ventricles. Heterogeneity in memory exists in pig ventricles. Because regions with the steepest restitution may also have the largest memory, our results suggest that heterogeneity in memory should also be factored in when predicting electrical stability. Copyright 2010 Elsevier Inc. All rights reserved.

Venous obstruction in permanent pacemaker patients: an isotopic study

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

Pauletti, M.; Di Ricco, G.; Solfanelli, S.

1981-01-01

Isotope venography was used to study the venous circulation proximal to the superior vena cava in two groups of pacemaker patients, one with a single endocavitary electrode and the other with multiple pacing catheters. A control group of patients without pacemakers was also studied. Numerous abnormalities were found, especially in the group with multiple electrodes. These findings suggest that venous obstruction is a common complication of endocardial pacing.

Cell migration during heart regeneration in zebrafish.

PubMed

Tahara, Naoyuki; Brush, Michael; Kawakami, Yasuhiko

2016-07-01

Zebrafish possess the remarkable ability to regenerate injured hearts as adults, which contrasts the very limited ability in mammals. Although very limited, mammalian hearts do in fact have measurable levels of cardiomyocyte regeneration. Therefore, elucidating mechanisms of zebrafish heart regeneration would provide information of naturally occurring regeneration to potentially apply to mammalian studies, in addition to addressing this biologically interesting phenomenon in itself. Studies over the past 13 years have identified processes and mechanisms of heart regeneration in zebrafish. After heart injury, pre-existing cardiomyocytes dedifferentiate, enter the cell cycle, and repair the injured myocardium. This process requires interaction with epicardial cells, endocardial cells, and vascular endothelial cells. Epicardial cells envelope the heart, while endocardial cells make up the inner lining of the heart. They provide paracrine signals to cardiomyocytes to regenerate the injured myocardium, which is vascularized during heart regeneration. In addition, accumulating results suggest that local migration of these major cardiac cell types have roles in heart regeneration. In this review, we summarize the characteristics of various heart injury methods used in the research community and regeneration of the major cardiac cell types. Then, we discuss local migration of these cardiac cell types and immune cells during heart regeneration. Developmental Dynamics 245:774-787, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Id4 functions downstream of Bmp signaling to restrict TCF function in endocardial cells during atrioventricular valve development.

PubMed

Ahuja, Suchit; Dogra, Deepika; Stainier, Didier Y R; Reischauer, Sven

2016-04-01

The atrioventricular canal (AVC) connects the atrial and ventricular chambers of the heart and its formation is critical for the development of the cardiac valves, chamber septation and formation of the cardiac conduction system. Consequently, problems in AVC formation can lead to congenital defects ranging from cardiac arrhythmia to incomplete cardiac septation. While our knowledge about early heart tube formation is relatively comprehensive, much remains to be investigated about the genes that regulate AVC formation. Here we identify a new role for the basic helix-loop-helix factor Id4 in zebrafish AVC valve development and function. id4 is first expressed in the AVC endocardium and later becomes more highly expressed in the atrial chamber. TALEN induced inactivation of id4 causes retrograde blood flow at the AV canal under heat induced stress conditions, indicating defects in AV valve function. At the molecular level, we found that id4 inactivation causes misexpression of several genes important for AVC and AV valve formation including bmp4 and spp1. We further show that id4 appears to control the number of endocardial cells that contribute to the AV valves by regulating Wnt signaling in the developing AVC endocardium. Copyright © 2016 Elsevier Inc. All rights reserved.

Wnt/β-catenin signaling enables developmental transitions during valvulogenesis

PubMed Central

Bosada, Fernanda M.; Devasthali, Vidusha; Jones, Kimberly A.; Stankunas, Kryn

2016-01-01

Heart valve development proceeds through coordinated steps by which endocardial cushions (ECs) form thin, elongated and stratified valves. Wnt signaling and its canonical effector β-catenin are proposed to contribute to endocardial-to-mesenchymal transformation (EMT) through postnatal steps of valvulogenesis. However, genetic redundancy and lethality have made it challenging to define specific roles of the canonical Wnt pathway at different stages of valve formation. We developed a transgenic mouse system that provides spatiotemporal inhibition of Wnt/β-catenin signaling by chemically inducible overexpression of Dkk1. Unexpectedly, this approach indicates canonical Wnt signaling is required for EMT in the proximal outflow tract (pOFT) but not atrioventricular canal (AVC) cushions. Furthermore, Wnt indirectly promotes pOFT EMT through its earlier activity in neighboring myocardial cells or their progenitors. Subsequently, Wnt/β-catenin signaling is activated in cushion mesenchymal cells where it supports FGF-driven expansion of ECs and then AVC valve extracellular matrix patterning. Mice lacking Axin2, a negative Wnt regulator, have larger valves, suggesting that accumulating Axin2 in maturing valves represents negative feedback that restrains tissue overgrowth rather than simply reporting Wnt activity. Disruption of these Wnt/β-catenin signaling roles that enable developmental transitions during valvulogenesis could account for common congenital valve defects. PMID:26893350

Automatic detection of left and right ventricles from CTA enables efficient alignment of anatomy with myocardial perfusion data.

PubMed

Piccinelli, Marina; Faber, Tracy L; Arepalli, Chesnal D; Appia, Vikram; Vinten-Johansen, Jakob; Schmarkey, Susan L; Folks, Russell D; Garcia, Ernest V; Yezzi, Anthony

2014-02-01

Accurate alignment between cardiac CT angiographic studies (CTA) and nuclear perfusion images is crucial for improved diagnosis of coronary artery disease. This study evaluated in an animal model the accuracy of a CTA fully automated biventricular segmentation algorithm, a necessary step for automatic and thus efficient PET/CT alignment. Twelve pigs with acute infarcts were imaged using Rb-82 PET and 64-slice CTA. Post-mortem myocardium mass measurements were obtained. Endocardial and epicardial myocardial boundaries were manually and automatically detected on the CTA and both segmentations used to perform PET/CT alignment. To assess the segmentation performance, image-based myocardial masses were compared to experimental data; the hand-traced profiles were used as a reference standard to assess the global and slice-by-slice robustness of the automated algorithm in extracting myocardium, LV, and RV. Mean distances between the automated and the manual 3D segmented surfaces were computed. Finally, differences in rotations and translations between the manual and automatic surfaces were estimated post-PET/CT alignment. The largest, smallest, and median distances between interactive and automatic surfaces averaged 1.2 ± 2.1, 0.2 ± 1.6, and 0.7 ± 1.9 mm. The average angular and translational differences in CT/PET alignments were 0.4°, -0.6°, and -2.3° about x, y, and z axes, and 1.8, -2.1, and 2.0 mm in x, y, and z directions. Our automatic myocardial boundary detection algorithm creates surfaces from CTA that are similar in accuracy and provide similar alignments with PET as those obtained from interactive tracing. Specific difficulties in a reliable segmentation of the apex and base regions will require further improvements in the automated technique.

Computational modeling and analysis for left ventricle motion using CT/Echo image fusion

NASA Astrophysics Data System (ADS)

Kim, Ji-Yeon; Kang, Nahyup; Lee, Hyoung-Euk; Kim, James D. K.

2014-03-01

In order to diagnose heart disease such as myocardial infarction, 2D strain through the speckle tracking echocardiography (STE) or the tagged MRI is often used. However out-of-plane strain measurement using STE or tagged MRI is inaccurate. Therefore, strain for whole organ which are analyzed by simulation of 3D cardiac model can be applied in clinical diagnosis. To simulate cardiac contraction in a cycle, cardiac physical properties should be reflected in cardiac model. The myocardial wall in left ventricle is represented as a transversely orthotropic hyperelastic material, with the fiber orientation varying sequentially from the epicardial surface, through about 0° at the midwall, to the endocardial surface. A time-varying elastance model is simulated to contract myocardial fiber, and physiological intraventricular systolic pressure curves are employed for the cardiac dynamics simulation in a cycle. And an exact description of the cardiac motion should be acquired in order that essential boundary conditions for cardiac simulation are obtained effectively. Real time cardiac motion can be acquired by using echocardiography and exact cardiac geometrical 3D model can be reconstructed using 3D CT data. In this research, image fusion technology from CT and echocardiography is employed in order to consider patient-specific left ventricle movement. Finally, longitudinal strain from speckle tracking echocardiography which is known to fit actual left ventricle deformation relatively well is used to verify these results.

Intractable Electrical Storm After Coronary Artery Bypass Grafting Originating in Abnormal Purkinje Fibers.

PubMed

Tokunaga, Chiho; Tsukada, Toru; Sakamoto, Hiroaki; Naruse, Yoshihisa; Yoshida, Kentaro; Sekiguchi, Yukio; Imai, Akito; Aonuma, Kazutaka; Hiramatsu, Yuji

2016-01-01

Electrical storm is a rare but critical complication following revascularization in patients with ischemic heart disease. We report the case of a 67-year-old man who developed drug refractory intractable electrical storm after emergent coronary artery bypass grafting for ischemic cardiomyopathy. The electrical storm was successfully eliminated by percutaneous endocardial radiofrequency catheter ablation targeting the abnormal Purkinje-related triggering ventricular premature contractions in a low-voltage zone. © 2015 Wiley Periodicals, Inc.

Transitions in early embryonic atrioventricular valvular function correspond with changes in cushion biomechanics that are predictable by tissue composition.

PubMed

Butcher, Jonathan T; McQuinn, Tim C; Sedmera, David; Turner, Debi; Markwald, Roger R

2007-05-25

Endocardial cushions are critical to maintain unidirectional blood flow under constantly increasing hemodynamic forces, but the interrelationship between endocardial cushion structure and the mechanics of atrioventricular junction function is poorly understood. Atrioventricular (AV) canal motions and blood velocities of embryonic chicks at Hamburger and Hamilton (HH) stages 17, 21, and 25 were quantified using ultrasonography. Similar to the embryonic zebrafish heart, the HH17 AV segment functions like a suction pump, with the cushions expanding in a wave during peak myocardial contraction and becoming undetectable during the relaxation phase. By HH25, the AV canal contributes almost nothing to the piston-like propulsion of blood, but the cushions function as stoppers apposing blood flow with near constant thickness. Using a custom built mesomechanical testing system, we quantified the nonlinear pseudoelastic biomechanics of developing AV cushions, and found that both AV cushions increased in effective modulus between HH17 and HH25. Enzymatic digestion of major structural constituent collagens or glycosaminoglycans resulted in distinctly different stress-strain curves suggestive of their individual contributions. Mixture theory using histologically determined volume fractions of cells, collagen, and glycosaminoglycans showed good prediction of cushion material properties regardless of stage and cushion position. These results have important implications in valvular development, as biomechanics may play a larger role in stimulating valvulogenic events than previously thought.

Protein kinase D2 controls cardiac valve formation in zebrafish by regulating histone deacetylase 5 activity.

PubMed

Just, Steffen; Berger, Ina M; Meder, Benjamin; Backs, Johannes; Keller, Andreas; Marquart, Sabine; Frese, Karen; Patzel, Eva; Rauch, Gerd-Jörg; Katus, Hugo A; Rottbauer, Wolfgang

2011-07-19

The molecular mechanisms that guide heart valve formation are not well understood. However, elucidation of the genetic basis of congenital heart disease is one of the prerequisites for the development of tissue-engineered heart valves. We isolated here a mutation in zebrafish, bungee (bng(jh177)), which selectively perturbs valve formation in the embryonic heart by abrogating endocardial Notch signaling in cardiac cushions. We found by positional cloning that the bng phenotype is caused by a missense mutation (Y849N) in zebrafish protein kinase D2 (pkd2). The bng mutation selectively impairs PKD2 kinase activity and hence Histone deacetylase 5 phosphorylation, nuclear export, and inactivation. As a result, the expression of Histone deacetylase 5 target genes Krüppel-like factor 2a and 4a, transcription factors known to be pivotal for heart valve formation and to act upstream of Notch signaling, is severely downregulated in bungee (bng) mutant embryos. Accordingly, the expression of Notch target genes, such as Hey1, Hey2, and HeyL, is severely decreased in bng mutant embryos. Remarkably, downregulation of Histone deacetylase 5 activity in homozygous bng mutant embryos can rescue the mutant phenotype and reconstitutes notch1b expression in atrioventricular endocardial cells. We demonstrate for the first time that proper heart valve formation critically depends on Protein kinase D2-Histone deacetylase 5-Krüppel-like factor signaling.

Myocardial expression of the vascular endothelial growth factor (VEGF) after endocardial laser revascularization (ELR)

NASA Astrophysics Data System (ADS)

Rommerscheid, Jan; Theisen, Dirk; Schmuecker, G.; Brinkmann, Ralf; Broll, R.

2001-10-01

Background. Endocardial laser revascularization (ELR) is a new technique to treat patients with severe coronary artery disease (CAD) in a percutaneous approach. The results show a significant improvement of symptoms, but the mechanism of action is still unknown. One main theory is the angiogenesis for which Vascular Endothelial Growth Factor (VEGF) is the keypromotor. We investigated immunohistochemically the VEGF-expression after ELR in porcine hearts over a timeperiod of four weeks. Methods. ELR was performed with a single-pulse Thulium:YAG laser. 15 pigs were treated with ELR and the hearts were harvested at five timeperiods: directly (group I), 3 days (group II), 1 week (group III), 2 weeks (group IV) and 4 weeks (group V) after ELR. Each group consisted of three pigs. Immunohistochemically the VEGF-expression was assessed by staining with a polyclonal antibody against VEGF and cellcounting using an expression index (VEGF-EI) Results. A maximum of VEGF-expression was found three days (group II) after ELR with a VEGF-EI of 97%. At 1 week (group III) the VEGF-EI was similar high with 93%. Along the timecourse the index decreased to 22% at 4 weeks (groupV). Conclusions. Our findings show that ELR leads to an local upregulation of VEGF around the channels. The resulting angiogenesis could be the mechanism for the relief of angina.

Sarcomere protein gene mutations and inherited heart disease: a beta-cardiac myosin heavy chain mutation causing endocardial fibroelastosis and heart failure.

PubMed

Kamisago, Mitsuhiro; Schmitt, Joachim P; McNamara, Dennis; Seidman, Christine; Seidman, J G

2006-01-01

Inherited human cardiomyopathies often lead to heart failure. A common feature of these conditions is that affected individuals can express the disease causing mutations for many years without showing clinical signs of the disease. Previous studies have demonstrated that sarcomere protein gene mutations can cause either dilated cardiomyopathy or hypertrophic cardiomyopathy. Here we demonstrate that the Arg442His missense mutation in beta-cardiac myosin heavy chain (betaMHC) causes dilated cardiomyopathy, endocardial fibroelastosis and heart failure at a very early age. Using standard genetic engineering tools we and others have made murine models by introducing human disease causing mutations into mice. The central hypothesis of these studies has been that by identifying the pathophysiological pathways activated by these mutations we can define enzymatic activities that are modified during the disease process and which may be involved in pathways that involve more common forms of cardiac disease. Murine models bearing different mutant myosins are being used to address whether each disease causing mutant betaMHC activates the same or different cellular pathways. Dissecting the molecular pathways modulated by mutations in sarcomere protein genes as well as other genes has already demonstrated that there are multiple pathways leading to cardiac remodelling and heart failure. Defining the mechanisms by which mutations in the same genes activate different cellular pathways remains an important question.

The use of echocardiography in Wolff-Parkinson-White syndrome.

PubMed

Cai, Qiangjun; Shuraih, Mossaab; Nagueh, Sherif F

2012-04-01

Endocardial mapping and radiofrequency catheter ablation are well established modalities for the diagnosis and treatment of patients with Wolff-Parkinson-White (WPW) syndrome associated with tachyarrhythmias. However, the electrophysiologic techniques are invasive, require radiation exposure, and lack spatial resolution of cardiac structures. A variety of echocardiographic techniques have been investigated as a non-invasive alternative for accessory pathway localization. Conventional M-mode echocardiography can detect the fine premature wall motion abnormalities associated with WPW syndrome. However, it is unable to identify the exact site of accessory pathway with sufficient accuracy. 2D, 2D-guided M-mode, and 2D phase analysis techniques are limited by image quality and endocardial border definition. Various modalities of tissue Doppler echocardiography significantly increase the accuracy of left-sided accessory pathway localization to 80-90% even in patients with poor acoustic window. However, right-sided pathways remain a diagnostic challenge. Strain echocardiography by speckle tracking has recently been evaluated and appears promising. Different cardiac abnormalities have been detected by echocardiography in WPW patients. Patients with WPW syndrome and tachyarrhythmias have impaired systolic and diastolic function which improves after radiofrequency ablation. Echocardiography is useful in identifying patient with accessory pathway-associated left ventricular dyssynchrony and dysfunction who may benefit from ablation therapy. Transesophageal and intracardiac echocardiography have been used to guide ablation procedure. Ablation-related complications detected by routine echocardiography are infrequent, rarely clinically relevant, and of limited value.

A Mutant Receptor Tyrosine Phosphatase, CD148, Causes Defects in Vascular Development

PubMed Central

Takahashi, Takamune; Takahashi, Keiko; St. John, Patricia L.; Fleming, Paul A.; Tomemori, Takuya; Watanabe, Toshio; Abrahamson, Dale R.; Drake, Christopher J.; Shirasawa, Takuji; Daniel, Thomas O.

2003-01-01

Vascularization defects in genetic recombinant mice have defined critical roles for a number of specific receptor tyrosine kinases. Here we evaluated whether an endothelium-expressed receptor tyrosine phosphatase, CD148 (DEP-1/PTPη), participates in developmental vascularization. A mutant allele, CD148ΔCyGFP, was constructed to eliminate CD148 phosphatase activity by in-frame replacement of cytoplasmic sequences with enhanced green fluorescent protein sequences. Homozygous mutant mice died at midgestation, before embryonic day 11.5 (E11.5), with vascularization failure marked by growth retardation and disorganized vascular structures. Structural abnormalities were observed as early as E8.25 in the yolk sac, prior to the appearance of intraembryonic defects. Homozygous mutant mice displayed enlarged vessels comprised of endothelial cells expressing markers of early differentiation, including VEGFR2 (Flk1), Tal1/SCL, CD31, ephrin-B2, and Tie2, with notable lack of endoglin expression. Increased endothelial cell numbers and mitotic activity indices were demonstrated. At E9.5, homozygous mutant embryos showed homogeneously enlarged primitive vessels defective in vascular remodeling and branching, with impaired pericyte investment adjacent to endothelial structures, in similarity to endoglin-deficient embryos. Developing cardiac tissues showed expanded endocardial projections accompanied by defective endocardial cushion formation. These findings implicate a member of the receptor tyrosine phosphatase family, CD148, in developmental vascular organization and provide evidence that it regulates endothelial proliferation and endothelium-pericyte interactions. PMID:12588999

Improved multimodality data fusion of late gadolinium enhancement MRI to left ventricular voltage maps in ventricular tachycardia ablation.

PubMed

Roujol, Sebastien; Basha, Tamer A; Tan, Alex; Khanna, Varun; Chan, Raymond H; Moghari, Mehdi H; Rayatzadeh, Hussein; Shaw, Jaime L; Josephson, Mark E; Nezafat, Reza

2013-05-01

Electroanatomical voltage mapping (EAVM) is commonly performed prior to catheter ablation of scar-related ventricular tachycardia (VT) to locate the arrhythmic substrate and to guide the ablation procedure. EAVM is used to locate the position of the ablation catheter and to provide a 3-D reconstruction of left-ventricular anatomy and scar. However, EAVM measurements only represent the endocardial scar with no transmural or epicardial information. Furthermore, EAVM is a time-consuming procedure, with a high operator dependence and has low sampling density, i.e., spatial resolution. Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) allows noninvasive assessment of scar morphology that can depict 3-D scar architecture. Despite the potential use of LGE as a roadmap for VT ablation for identification of arrhythmogenic substrate, its utility has been very limited. To allow for identification of VT substrate, a correlation is needed between the substrates identified by EAVM as the gold standard and LGE-MRI scar characteristics. To do so, a system must be developed to fuse the datasets from these modalities. In this study, a registration pipeline for the fusion of LGE-MRI and EAVM data is presented. A novel surface registration algorithm is proposed, integrating the matching of global scar areas as an additional constraint in the registration process. A preparatory landmark registration is initially performed to expedite the convergence of the algorithm. Numerical simulations were performed to evaluate the accuracy of the registration in the presence of errors in identifying landmarks in EAVM or LGE-MRI datasets as well as additional errors due to respiratory or cardiac motion. Subsequently, the accuracy of the proposed fusion system was evaluated in a cohort of ten patients undergoing VT ablation where both EAVM and LGE-MRI data were available. Compared to landmark registration and surface registration, the presented method achieved significant improvement in registration error. The proposed data fusion system allows the fusion of EAVM and LGE-MRI data in VT ablation with registration errors less than 3.5  mm.

Contrast-enhanced cardiac C-arm CT evaluation of radiofrequency ablation lesions in the left ventricle

PubMed Central

Girard, Erin E; Al-Ahmad, Amin A; Rosenberg, Jarrett; Luong, Richard; Moore, Teri; Lauritsch, Günter; Boese, Jan; Fahrig, Rebecca

2011-01-01

Objectives The purpose of this study was to evaluate use of cardiac C-arm computed tomography (CT) in the assessment of the dimensions and temporal characteristics of radiofrequency ablation (RFA) lesions. This imaging modality uses a standard C-arm fluoroscopy system rotating around the patient, providing CT-like images during the RFA procedure. Background Both magnetic resonance imaging (MRI) and CT can be used to assess myocardial necrotic tissue. Several studies have reported visualizing cardiac RF ablation lesions with MRI, however obtaining MR images during interventional procedures is not common practice. Direct visualization of RFA lesions using C-arm CT during the procedure may improve outcomes and circumvent complications associated with cardiac ablation procedures. Methods RFA lesions were created on the endocardial surface of the left ventricle of 9 swine using a 7-F RF ablation catheter. An ECG-gated C-arm CT imaging protocol was used to acquire projection images during iodine contrast injection and following the injection every 5 min for up to 30 min, with no additional contrast. Reconstructed images were analyzed offline. The mean and standard deviation of the signal intensity of the lesion and normal myocardium were measured in all images in each time series. Lesion dimensions and area were measured and compared in pathologic specimens and C-arm CT images. Results All ablation lesions (n=29) were visualized and lesion dimensions, as measured on C-arm CT, correlated well with postmortem tissue measurements (1D dimensions : concordance correlation = 0.87; area : concordance correlation = 0.90). Lesions were visualized as a perfusion defect on first-pass C-arm CT images with a signal intensity 95 HU lower than normal myocardium (95% confidence interval: -111 to -79 HU). Images acquired at 1 and 5 minutes exhibited an enhancing ring surrounding the perfusion defect in 24 (83%) lesions. Conclusions RFA lesion size, including transmurality, can be assessed using ECG-gated cardiac C-arm CT in the interventional suite. Visualization of RFA lesions using cardiac C-arm CT may facilitate the assessment of adequate lesion delivery and provide valuable feedback during cardiac ablation procedures. PMID:21414574

A New MRI-Based Model of Heart Function with Coupled Hemodynamics and Application to Normal and Diseased Canine Left Ventricles

PubMed Central

Choi, Young Joon; Constantino, Jason; Vedula, Vijay; Trayanova, Natalia; Mittal, Rajat

2015-01-01

A methodology for the simulation of heart function that combines an MRI-based model of cardiac electromechanics (CE) with a Navier–Stokes-based hemodynamics model is presented. The CE model consists of two coupled components that simulate the electrical and the mechanical functions of the heart. Accurate representations of ventricular geometry and fiber orientations are constructed from the structural magnetic resonance and the diffusion tensor MR images, respectively. The deformation of the ventricle obtained from the electromechanical model serves as input to the hemodynamics model in this one-way coupled approach via imposed kinematic wall velocity boundary conditions and at the same time, governs the blood flow into and out of the ventricular volume. The time-dependent endocardial surfaces are registered using a diffeomorphic mapping algorithm, while the intraventricular blood flow patterns are simulated using a sharp-interface immersed boundary method-based flow solver. The utility of the combined heart-function model is demonstrated by comparing the hemodynamic characteristics of a normal canine heart beating in sinus rhythm against that of the dyssynchronously beating failing heart. We also discuss the potential of coupled CE and hemodynamics models for various clinical applications. PMID:26442254

Spatial distributions of Kv4 channels and KChip2 isoforms in the murine heart based on laser capture microdissection.

PubMed

Teutsch, Christine; Kondo, Richard P; Dederko, Dorothy A; Chrast, Jacqueline; Chien, Kenneth R; Giles, Wayne R

2007-03-01

Regional differences in repolarizing K(+) current densities and expression levels of their molecular components are important for coordinating the pattern of electrical excitation and repolarization of the heart. The small size of hearts from mice may obscure these interventricular and/or transmural expression differences of K(+) channels. We have examined this possibility in adult mouse ventricle using a technology that provides very high spatial resolution of tissue collection. Conventional manual dissection and laser capture microdissection (LCM) were utilized to dissect tissue from distinct ventricular regions. RNA was isolated from epicardial, mid-myocardial and endocardial layers of both the right and left ventricles. Real-time RT-PCR was used to quantify the transcript expression in these different regions. LCM revealed significant interventricular and transmural gradients for both Kv4.2 and the alpha-subunit of KChIP2. The expression profile of a second K(+) channel transcript, Kir2.1, which is responsible for the inwardly rectifying K(+) current I(k1), showed no interventricular or transmural gradients and therefore served as a negative control. Our findings are in contrast to previous reports of a relatively uniform left ventricular transmural pattern of expression of Kv4.2, Kv4.3 and KChIP2 in adult mouse heart, which appear to be different than that in larger mammals. Specifically, our results demonstrate significant epi- to endocardial differences in the patterns of expression of both Kv4.2 and KChIP2.

Nuclear Membranes ETB Receptors Mediate ET-1-induced Increase of Nuclear Calcium in Human Left Ventricular Endocardial Endothelial Cells.

PubMed

Jules, Farah; Avedanian, Levon; Al-Khoury, Johny; Keita, Ramatoulaye; Normand, Alexandre; Bkaily, Ghassan; Jacques, Danielle

2015-07-01

In fetal human left ventricular endocardial endothelial cells (EECLs), both plasma membrane (PM) ET(A)R and ET(B)R were reported to mediate ET-1-induced increase of intracellular calcium [Ca](i); however, this effect was mediated by ET(A)R in right EECs (EECRs). In this study, we verified whether, as for the PM, nuclear membranes (NMs) ET-1 receptors activation in EECLs and EECRs induce an increase of nuclear calcium ([Ca](n)) and if this effect is mediated through the same receptor type as in PM. Using a plasmalemma-perforated technique and 3D confocal microscopy, our results showed that, as in PM intact cells, superfusion of nuclei of both cell types with cytosolic ET-1 induced a concentration-dependent sustained increase of [Ca](n). In EECRs, the ET(A)R antagonist prevented the effect of ET-1 on [Ca](n) without affecting EECLs. However, in both cell types, the effect of cytosolic ET-1 on [Ca](n) was prevented by the ETBR antagonist. In conclusion, both NMs' ET(A)R and ET(B)R mediated the effect of cytosolic ET-1 on [Ca](n) in EECRs. In contrast, only NMs' ET(B)R activation mediated the effect of cytosolic ET-1 in EECLs. Hence, the type of NMs' receptors mediating the effect of ET-1 on [Ca](n) are different from those of PM mediating the increase in [Ca](i).

Second Harmonic Imaging improves Echocardiograph Quality on board the International Space Station

NASA Technical Reports Server (NTRS)

Garcia, Kathleen; Sargsyan, Ashot; Hamilton, Douglas; Martin, David; Ebert, Douglas; Melton, Shannon; Dulchavsky, Scott

2008-01-01

Ultrasound (US) capabilities have been part of the Human Research Facility (HRF) on board the International Space Station (ISS) since 2001. The US equipment on board the ISS includes a first-generation Tissue Harmonic Imaging (THI) option. Harmonic imaging (HI) is the second harmonic response of the tissue to the ultrasound beam and produces robust tissue detail and signal. Since this is a first-generation THI, there are inherent limitations in tissue penetration. As a breakthrough technology, HI extensively advanced the field of ultrasound. In cardiac applications, it drastically improves endocardial border detection and has become a common imaging modality. U.S. images were captured and stored as JPEG stills from the ISS video downlink. US images with and without harmonic imaging option were randomized and provided to volunteers without medical education or US skills for identification of endocardial border. The results were processed and analyzed using applicable statistical calculations. The measurements in US images using HI improved measurement consistency and reproducibility among observers when compared to fundamental imaging. HI has been embraced by the imaging community at large as it improves the quality and data validity of US studies, especially in difficult-to-image cases. Even with the limitations of the first generation THI, HI improved the quality and measurability of many of the downlinked images from the ISS and should be an option utilized with cardiac imaging on board the ISS in all future space missions.

Single-site access robot-assisted epicardial mapping with a snake robot: preparation and first clinical experience.

PubMed

Neuzil, Petr; Cerny, Stepan; Kralovec, Stepan; Svanidze, Oleg; Bohuslavek, Jan; Plasil, Petr; Jehlicka, Pavel; Holy, Frantisek; Petru, Jan; Kuenzler, Richard; Sediva, Lucie

2013-06-01

CardioARM, a highly flexible "snakelike" medical robotic system (Medrobotics, Raynham, MA), has been developed to allow physicians to view, access, and perform complex procedures intrapericardially on the beating heart through a single-access port. Transthoracic epicardial catheter mapping and ablation has emerged as a strategy to treat arrhythmias, particularly ventricular arrhythmias, originating from the epicardial surface. The aim of our investigation was to determine whether the CardioARM could be used to diagnose and treat ventricular tachycardia (VT) of epicardial origin. Animal and clinical studies of the CardioARM flexible robot were performed in hybrid surgical-electrophysiology settings. In a porcine model study, single-port pericardial access, navigation, mapping, and ablation were performed in nine animals. The device was then used in a small, single-center feasibility clinical study. Three patients, all with drug-refractory VT and multiple failed endocardial ablation attempts, underwent epicardial mapping with the flexible robot. In all nine animals, navigation, mapping, and ablation were successful without hemodynamic compromise. In the human study, all three patients demonstrated a favorable safety profile, with no major adverse events through a 30-day follow-up. Two cases achieved technical success, in which an electroanatomic map of the epicardial ventricle surface was created; in the third case, blood obscured visualization. These results, although based on a limited number of experimental animals and patients, show promise and suggest that further clinical investigation on the use of the flexible robot in patients requiring epicardial mapping of VT is warranted.

Photoacoustic characterization of radiofrequency ablation lesions

NASA Astrophysics Data System (ADS)

Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav

2012-02-01

Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh (i.e., never frozen) porcine hearts was harvested within 24 hours of the animals' sacrifice. A THERMOCOOLR Ablation System (Biosense Webster, Inc.) operating at 40 W for 30-60 s was used to induce lesions through the endocardial and epicardial walls of the cardiac samples. Following lesion creation, the ablated tissue samples were placed in 25 °C saline to allow for multi-wavelength PA imaging. Samples were imaged with a VevoR 2100 ultrasound system (VisualSonics, Inc.) using a modified 20-MHz array that could provide laser irradiation to the sample from a pulsed tunable laser (Newport Corp.) to allow for co-registered photoacoustic-ultrasound (PAUS) imaging. PA imaging was conducted from 750-1064 nm, with a surface fluence of approximately 15 mJ/cm2 maintained during imaging. In this preliminary study with PA imaging, the ablated region could be well visualized on the surface of the sample, with contrasts of 6-10 dB achieved at 750 nm. Although imaging penetration depth is a concern, PA imaging shows promise in being able to reliably visualize RF ablation lesions.

HIS bundle electrogram in rheumatic mitral valve disease with special reference to Bachmann's bundle block in P mitrale.

PubMed

Lee, Y S; Lien, W P

1975-08-01

HBEs were recorded from either the right or left ventricle or simultaneously from both in 26 patients with chronic rheumatic mitral stenosis alone or in association with other mild valvular lesions during the diagnostic cardiac catheterization. Eleven of the patients had auricular fibrillation. Of the remaining 15 patients with sinus mechanism and P mitrale in the surface electrocardiogram, 12 were noted to have H potential preceded the termination of P wave and gave P2H interval of negative value- so-called "Bachmann's bundle block". Among these, double atrial activities (A and A' waves) could be identified on the HBE recorded from the left ventricular endocardial surface with catheter electrodes positioned at the subarotic region in 7 patients studied. Interatrial conduction time (P1A' interval) measured in these patients was prolonged in all and ranged from 47 to 82 with an average of 66 msec. Prolongation of intraatrial (or internodal) conduction time was noted in only one patient who also had first degree A-V block and prolonged A-H interval. There was no correlation of either P1P2 or P2H interval to the degree of left atrial enlargement. The P1P2 or P2H interval also had no correlation with hemodynamic parameters. In patients with auricular fibrillation, all impulses unable to conduct to the ventricle were blocked proximal to the His bundle and concealed conduction was not observed distal to it.

How the knowledge of genetic "makeup" and cellular data can affect the analysis of repolarization in surface electrocardiogram.

PubMed

Shimizu, Wataru

2010-01-01

This review article sought to describe patterns of repolarization on the surface electrocardiogram in inherited cardiac arrhythmias and to discuss how the knowledge of genetic makeup and cellular data can affect the analysis based on the data derived from the experimental studies using arterially perfused canine ventricular wedge preparations. Molecular genetic studies have established a link between a number of inherited cardiac arrhythmia syndromes and mutations in genes encoding cardiac ion channels or membrane components during the past 2 decades. Twelve forms of congenital long QT syndrome have been so far identified, and genotype-phenotype correlations have been investigated especially in the 3 major genotypes-LQT1, LQT2, and LQT3. Abnormal T waves are reported in the LQT1, LQT2, and LQT3, and the differences in the time course of repolarization of the epicardial, midmyocardial, and endocardial cells give rise to voltage gradients responsible for the manifestation of phenotypic appearance of abnormal T waves. Brugada syndrome is characterized by ST-segment elevation in leads V1 to V3 and an episode of ventricular fibrillation, in which 7 genotypes have been reported. An intrinsically prominent transient outward current (I(to))-mediated action potential notch and a subsequent loss of action potential dome in the epicardium, but not in the endocardium of the right ventricular outflow tract, give rise to a transmural voltage gradient, resulting in ST-segment elevation, and a subsequent phase 2 reentry-induced ventricular fibrillation. In conclusion, transmural electrical heterogeneity of repolarization across the ventricular wall profoundly affects the phenotypic manifestation of repolarization patterns on the surface electrocardiogram in inherited cardiac arrhythmias. Copyright © 2010 Elsevier Inc. All rights reserved.

Segmentation of the heart and major vascular structures in cardiovascular CT images

NASA Astrophysics Data System (ADS)

Peters, J.; Ecabert, O.; Lorenz, C.; von Berg, J.; Walker, M. J.; Ivanc, T. B.; Vembar, M.; Olszewski, M. E.; Weese, J.

2008-03-01

Segmentation of organs in medical images can be successfully performed with shape-constrained deformable models. A surface mesh is attracted to detected image boundaries by an external energy, while an internal energy keeps the mesh similar to expected shapes. Complex organs like the heart with its four chambers can be automatically segmented using a suitable shape variablility model based on piecewise affine degrees of freedom. In this paper, we extend the approach to also segment highly variable vascular structures. We introduce a dedicated framework to adapt an extended mesh model to freely bending vessels. This is achieved by subdividing each vessel into (short) tube-shaped segments ("tubelets"). These are assigned to individual similarity transformations for local orientation and scaling. Proper adaptation is achieved by progressively adapting distal vessel parts to the image only after proximal neighbor tubelets have already converged. In addition, each newly activated tubelet inherits the local orientation and scale of the preceeding one. To arrive at a joint segmentation of chambers and vasculature, we extended a previous model comprising endocardial surfaces of the four chambers, the left ventricular epicardium, and a pulmonary artery trunk. Newly added are the aorta (ascending and descending plus arch), superior and inferior vena cava, coronary sinus, and four pulmonary veins. These vessels are organized as stacks of triangulated rings. This mesh configuration is most suitable to define tubelet segments. On 36 CT data sets reconstructed at several cardiac phases from 17 patients, segmentation accuracies of 0.61-0.80mm are obtained for the cardiac chambers. For the visible parts of the newly added great vessels, surface accuracies of 0.47-1.17mm are obtained (larger errors are asscociated with faintly contrasted venous structures).

A STUDY OF CHANGES IN DEFORMATION AND METABOLISM IN LEFT VENTRICLE AS A FUNCTION OF HYPERTROPHY IN SPONTANEOUS HYPERTENSIVE RATS USING MICROPET TECHNOLOGY

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

Gullberg, Grant, T; Huesman, Ronald, H; Reutter, Bryan, W

Problem: In the case of hypertrophy caused by pressure overload (hypertension) there is an increase in cardiac mass and modification cardiac metabolism. Aim: This study was designed to study the changes in glucose metabolism, ejection fraction, and deformation in the left ventricle with the progression of hypertrophy in spontaneous hypertensive rats (SHR). Methods: Dynamic PET data were acquired using the microPET II at UC Davis. Two rats were imaged at 10-week intervals for 18 months. Each time a dose of approximately 1- 1.5 mCi of F-18-FDG was injected into a normotensive Wistar Kyoto (WKY) rat and the same dose wasmore » injected into a SHR rat. Each rat was imaged using a gated dynamic acquisition for 80 minutes acquiring list mode data with cardiac gating of approximately 600-900 million total counts. For the analysis of glucose of metabolism, the list mode data were histogrammed into a dynamic sequence (42 frames over 80 mins). For each time frame, projection data of 1203 140x210 sinograms of 0.582 mm bins were formed by summing the last three gates before and one after the R-wave trigger to correspond to the diastolic phase of the cardiac cycle. Dynamic sequences of 128x128x83 matrices of 0.4x0.4x0.582 mm3 voxels in x, y, and z were reconstructed using an iterative MAP reconstruction which used a prior that penalized the high frequency components of the reconstruction using appropriate weighting between 26 nearest neighboring voxels. Time activity curves were generated from the dynamic reconstructed sequence for the blood and left ventricular tissue regions of interest which were fit to a 2-compartment model to obtain a least squares fit for the kinetic parameters. For the analysis of deformation, the list mode data were histogrammed into 8 gates of the cardiac cycle, each gate was the total sum of the later 60 mins of the 80 min acquisition. Images of 128x128x83 matrices for each gate were reconstructed using the same iterative MAP reconstruction used to reconstruct the dynamic sequence. The in-plane image dimensions were doubled to 256x256x83 in order to increase the resolution for the Warping analyses. These image data sets were then cropped to 128x128x83. The end-systolic image data sets were designated as the template images and the end-diastole image data sets were designated as the target images, thus providing an analysis of the diastolic relaxation and filling phases of the cardiac cycle. The template images were manually segmented to create surface definitions representing the epi- and endocardial surfaces. Finite element models of the left ventricles were created using the segmented surfaces and defining a transversely isotropic material with fiber angles varying from the epicardial surface to the endocardial surface. A Warping analyses was performed to obtain the LV strain tensor and fiber stretch distributions. Results: In one study, the average first principal Green-Lagrange strain, fiber stretch, ejection fraction, and metabolic rate of F-18-FDG was 0.22, 1.08, 80%, 0.1 for the WKY rat and 0.16, 1.06, 50%, 0.25 for the SHR rat, respectively. These same rats studied a year later presented with a metabolic rate of F-18-FDG of 0.11 and 0.25 for the WKY and SHR, respectively. A follow-up study the average strain (n=10) and ejection fraction (n=18) was 0.21, 72.7% for WKY and 0.17, 69.8% for the SHR, respectively. Conclusion: In the case of pressure overload there is an increased reliance on carbohydrate oxidation in an attempt to maintain contractile function.« less

[Catheter ablation of ectopic incessant atrial tachycardia using radiofrequency. Reversion of tachycardiomyopathy].

PubMed

de Paola, A A; Mendonça, A; Balbão, C E; Tavora, M Z; da Silva, R M; Hara, V M; Guiguer Júnior, N; Vattimo, A C; Souza, I A; Portugal, O P

1993-10-01

A 8-year-old female patient with refractory incessant atrial tachycardia, very symptomatic and with left ventricular ejection fraction of 0.25. Electrophysiological study and endocardial mapping localized the site of the origin of atrial tachycardia in the superior right atrium. In this site 2 applications of radiofrequency current (25V, 20 and 50 seconds) resulted in termination of the atrial tachycardia. She was discharged off antiarrhythmic drugs and after 2 months ejection fraction was 0.52. She was completely asymptomatic 6 months after ablation procedure.

Primary Mural Endocarditis Without Valvular Involvement.

PubMed

Tahara, Mai; Nagai, Tomoo; Takase, Yoshiyuki; Takiguchi, Shunichi; Tanaka, Yoshiaki; Kunihara, Takashi; Arakawa, Junko; Nakaya, Kazuhiro; Hamabe, Akira; Gatate, Youdou; Kujiraoka, Takehiko; Tabata, Hirotsugu; Katsushika, Shuichi

2017-03-01

Primary mural endocarditis is an extremely rare infection in which nonvalvular endocardial involvement is seen without any cardiac structural abnormalities such as ventricular septal defects. The rapid and precise diagnosis of this disease remains challenging. We present 2 cases (67- and 47-year-old male patients) of pathologically confirmed primary mural endocarditis that could have been detected by initial transthoracic echocardiography in the emergency department. Transthoracic echocardiography and transesophageal echocardiography play critical roles in the early recognition and confirmation of primary mural endocarditis. © 2017 by the American Institute of Ultrasound in Medicine.

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.

Fully automated segmentation of left ventricle using dual dynamic programming in cardiac cine MR images

NASA Astrophysics Data System (ADS)

Jiang, Luan; Ling, Shan; Li, Qiang

2016-03-01

Cardiovascular diseases are becoming a leading cause of death all over the world. The cardiac function could be evaluated by global and regional parameters of left ventricle (LV) of the heart. The purpose of this study is to develop and evaluate a fully automated scheme for segmentation of LV in short axis cardiac cine MR images. Our fully automated method consists of three major steps, i.e., LV localization, LV segmentation at end-diastolic phase, and LV segmentation propagation to the other phases. First, the maximum intensity projection image along the time phases of the midventricular slice, located at the center of the image, was calculated to locate the region of interest of LV. Based on the mean intensity of the roughly segmented blood pool in the midventricular slice at each phase, end-diastolic (ED) and end-systolic (ES) phases were determined. Second, the endocardial and epicardial boundaries of LV of each slice at ED phase were synchronously delineated by use of a dual dynamic programming technique. The external costs of the endocardial and epicardial boundaries were defined with the gradient values obtained from the original and enhanced images, respectively. Finally, with the advantages of the continuity of the boundaries of LV across adjacent phases, we propagated the LV segmentation from the ED phase to the other phases by use of dual dynamic programming technique. The preliminary results on 9 clinical cardiac cine MR cases show that the proposed method can obtain accurate segmentation of LV based on subjective evaluation.

Origin and pharmacological response of atrial tachyarrhythmias induced by activation of mediastinal nerves in canines.

PubMed

Armour, J Andrew; Richer, Louis-Philippe; Pagé, Pierre; Vinet, Alain; Kus, Teresa; Vermeulen, Michel; Nadeau, Réginald; Cardinal, René

2005-03-31

We sought to determine the sites of origin of atrial tachyarrhythmias induced by activating mediastinal nerves, as well as the response of such arrhythmias to autonomic modulation. Under general anaesthesia, atrioventricular block was induced after thoracotomy in 19 canines. Brief trains of 5 electrical stimuli were delivered to right-sided mediastinal nerves during the atrial refractory period. Unipolar electrograms were recorded from 191 right and left atrial epicardial sites under several conditions, i.e. (i) with intact nervous systems and following (ii) acute decentralization of the intrathoracic nervous system or administration of (iii) atropine, (iv) timolol, (v) hexamethonium. Concomitant right atrial endocardial mapping was performed in 7 of these dogs. Mediastinal nerve stimulation consistently initiated bradycardia followed by atrial tachyarrhythmias. In the initial tachyarrhythmia beats, early epicardial breakthroughs were identified in the right atrial free wall (28/50 episodes) or Bachmann bundle region (22/50), which corresponded to endocardial sites of origin associated with the right atrial subsidiary pacemaker complex, i.e. the crista terminalis and dorsal locations including the right atrial aspect of the interatrial septum. Neuronally induced responses were eliminated by atropine, modified by timolol and unaffected by acute neuronal decentralization. After hexamethonium, responses to extra-pericardial but not intra-pericardial nerve stimulation were eliminated. It is concluded that concomitant activation of cholinergic and adrenergic efferent intrinsic cardiac neurons induced by right-sided efferent neuronal stimulation initiates atrial tachyarrhythmias that originate from foci anatomically related to the right atrial pacemaker complex and tissues underlying major atrial ganglionated plexuses.

Dofetilide promotes repolarization abnormalities in perfused Guinea-pig heart.

PubMed

Osadchii, Oleg E

2012-12-01

Dofetilide is class III antiarrhythmic agent which prolongs cardiac action potential duration because of selective inhibition of I (Kr), the rapid component of the delayed rectifier K(+) current. Although clinical studies reported on proarrhythmic risk associated with dofetilide treatment, the contributing electrophysiological mechanisms remain poorly understood. This study was designed to determine if dofetilide-induced proarrhythmia may be attributed to abnormalities in ventricular repolarization and refractoriness. The monophasic action potential duration and effective refractory periods (ERP) were assessed at distinct epicardial and endocardial sites along with volume-conducted ECG recordings in isolated, perfused guinea-pig heart preparations. Dofetilide was found to produce the reverse rate-dependent prolongation of ventricular repolarization, increased the steepness of action potential duration rate adaptation, and amplified transepicardial variability in electrical restitution kinetics. Dofetilide also prolonged the T peak-to-end interval on ECG, and elicited a greater prolongation of endocardial than epicardial ERP, thereby increasing transmural dispersion of refractoriness. At epicardium, dofetilide prolonged action potential duration to a greater extent than ERP, thus extending the critical interval for ventricular re-excitation. This change was associated with triangulation of epicardial action potential because of greater dofetilide-induced prolonging effect at 90 % than 30 % repolarization. Premature ectopic beats and spontaneous short-lasting episodes of monomorphic ventricular tachycardia were observed in 44 % of dofetilide-treated heart preparations. Proarrhythmic potential of dofetilide in guinea-pig heart is attributed to steepened electrical restitution, increased transepicardial variability in electrical restitution kinetics, amplified transmural dispersion of refractoriness, increased critical interval for ventricular re-excitation, and triangulation of epicardial action potential.

A Prospective Study of Ripple Mapping the Post-Infarct Ventricular Scar to Guide Substrate Ablation for Ventricular Tachycardia.

PubMed

Luther, Vishal; Linton, Nick W F; Jamil-Copley, Shahnaz; Koa-Wing, Michael; Lim, Phang Boon; Qureshi, Norman; Ng, Fu Siong; Hayat, Sajad; Whinnett, Zachary; Davies, D Wyn; Peters, Nicholas S; Kanagaratnam, Prapa

2016-06-01

Post-infarct ventricular tachycardia is associated with channels of surviving myocardium within scar characterized by fractionated and low-amplitude signals usually occurring late during sinus rhythm. Conventional automated algorithms for 3-dimensional electro-anatomic mapping cannot differentiate the delayed local signal of conduction within the scar from the initial far-field signal generated by surrounding healthy tissue. Ripple mapping displays every deflection of an electrogram, thereby providing fully informative activation sequences. We prospectively used CARTO-based ripple maps to identify conducting channels as a target for ablation. High-density bipolar left ventricular endocardial electrograms were collected using CARTO3v4 in sinus rhythm or ventricular pacing and reviewed for ripple mapping conducting channel identification. Fifteen consecutive patients (median age 68 years, left ventricular ejection fraction 30%) were studied (6 month preprocedural implantable cardioverter defibrillator therapies: median 19 ATP events [Q1-Q3=4-93] and 1 shock [Q1-Q3=0-3]). Scar (<1.5 mV) occupied a median 29% of the total surface area (median 540 points collected within scar). A median of 2 ripple mapping conducting channels were seen within each scar (length 60 mm; initial component 0.44 mV; delayed component 0.20 mV; conduction 55 cm/s). Ablation was performed along all identified ripple mapping conducting channels (median 18 lesions) and any presumed interconnected late-activating sites (median 6 lesions; Q1-Q3=2-12). The diastolic isthmus in ventricular tachycardia was mapped in 3 patients and colocated within the ripple mapping conducting channels identified. Ventricular tachycardia was noninducible in 85% of patients post ablation, and 71% remain free of ventricular tachycardia recurrence at 6-month median follow-up. Ripple mapping can be used to identify conduction channels within scar to guide functional substrate ablation. © 2016 American Heart Association, Inc.

Biomechanics of the Chick Embryonic Heart Outflow Tract at HH18 Using 4D Optical Coherence Tomography Imaging and Computational Modeling

PubMed Central

Liu, Aiping; Yin, Xin; Shi, Liang; Li, Peng; Thornburg, Kent L.; Wang, Ruikang; Rugonyi, Sandra

2012-01-01

During developmental stages, biomechanical stimuli on cardiac cells modulate genetic programs, and deviations from normal stimuli can lead to cardiac defects. Therefore, it is important to characterize normal cardiac biomechanical stimuli during early developmental stages. Using the chicken embryo model of cardiac development, we focused on characterizing biomechanical stimuli on the Hamburger–Hamilton (HH) 18 chick cardiac outflow tract (OFT), the distal portion of the heart from which a large portion of defects observed in humans originate. To characterize biomechanical stimuli in the OFT, we used a combination of in vivo optical coherence tomography (OCT) imaging, physiological measurements and computational fluid dynamics (CFD) modeling. We found that, at HH18, the proximal portion of the OFT wall undergoes larger circumferential strains than its distal portion, while the distal portion of the OFT wall undergoes larger wall stresses. Maximal wall shear stresses were generally found on the surface of endocardial cushions, which are protrusions of extracellular matrix onto the OFT lumen that later during development give rise to cardiac septa and valves. The non-uniform spatial and temporal distributions of stresses and strains in the OFT walls provide biomechanical cues to cardiac cells that likely aid in the extensive differential growth and remodeling patterns observed during normal development. PMID:22844414

Measurement of left ventricular mass in vivo using gated nuclear magnetic resonance imaging.

PubMed

Florentine, M S; Grosskreutz, C L; Chang, W; Hartnett, J A; Dunn, V D; Ehrhardt, J C; Fleagle, S R; Collins, S M; Marcus, M L; Skorton, D J

1986-07-01

Alterations of left ventricular mass occur in a variety of congenital and acquired heart diseases. In vivo determination of left ventricular mass, using several different techniques, has been previously reported. Problems inherent in some previous methods include the use of ionizing radiation, complicated geometric assumptions and invasive techniques. We tested the ability of gated nuclear magnetic resonance imaging to determine in vivo left ventricular mass in animals. By studying both dogs (n = 9) and cats (n = 2) of various sizes, a broad range of left ventricular mass (7 to 133 g) was examined. With a 0.5 tesla superconducting nuclear magnetic resonance imaging system the left ventricle was imaged in the transaxial plane and multiple adjacent 10 mm thick slices were obtained. Endocardial and epicardial edges were manually traced in each computer-displayed image. The wall area of each image was determined by computer and the areas were summed and multiplied by the slice thickness and the specific gravity of muscle, providing calculated left ventricular mass. Calculated left ventricular mass was compared with actual postmortem left ventricular mass using linear regression analysis. An excellent relation between calculated and actual mass was found (r = 0.95; SEE = 13.1 g; regression equation: magnetic resonance mass = 0.95 X actual mass + 14.8 g). Intraobserver and interobserver reproducibility were also excellent (r = 0.99). Thus, gated nuclear magnetic resonance imaging can accurately determine in vivo left ventricular mass in anesthetized animals.

[Reoperations in bradyarrhythmic forms of disorders of heart conductivity].

PubMed

Amanov, A A; Guliamov, D S; Umarov, V M; Khan, N I; Asanov, R V

1990-06-01

Under analysis were causes of reoperations in bradyarrhythmic forms of disturbances of conductivity of the heart. 565 operations connected with electrocardiostimulation were performed on 276 patients. Reoperations in patients with the myocardial stimulation were made on 63 patients, with the endocardial stimulation--in 226 patients. Causes of reoperations were as follows: depletion of the source of ECS--31.5%; dislocation of the electrode--8.2%; damage of the electrode--15%, suppuration of the bed, decubitus of the stimulator--28.8%; competing rate--7.4%; break of the contact in the connecting system of the electrode and cardiostimulator--9.4%.

Phrenic nerve injury: An underrecognized and potentially preventable complication of pulmonary vein isolation using a wide-area circumferential ablation approach.

PubMed

Yong Ji, Sang; Dewire, Jane; Barcelon, Bernadette; Philips, Binu; Catanzaro, John; Nazarian, Saman; Cheng, Alan; Spragg, David; Tandri, Harikrishna; Bansal, Sandeep; Ashikaga, Hiroshi; Rickard, Jack; Kolandaivelu, Aravindan; Sinha, Sunil; Marine, Joseph E; Calkins, Hugh; Berger, Ronald

2013-10-01

Phrenic nerve injury (PNI) is a well-known, although uncommon, complication of pulmonary vein isolation (PVI) using radiofrequency energy. Currently, there is no consensus about how to avoid or minimize this injury. The purpose of this study was to determine how often the phrenic nerve, as identified using a high-output pacing, lies along the ablation trajectory of a wide-area circumferential lesion set. We also sought to determine if PVI can be achieved without phrenic nerve injury by modifying the ablation lesion set so as to avoid those areas where phrenic nerve capture (PNC) is observed. We prospectively enrolled 100 consecutive patients (age 61.7 ± 9.2 years old, 75 men) who underwent RF PVI using a wide-area circumferential ablation approach. A high-output (20 mA at 2 milliseconds) endocardial pacing protocol was performed around the right pulmonary veins and the carina where a usual ablation lesion set would be made. A total of 30% of patients had PNC and required modification of ablation lines. In the group of patients with PNC, the carina was the most common site of capture (85%) followed by anterior right superior pulmonary vein (RSPV) (70%) and anterior right inferior pulmonary vein (RIPV) (30%). A total of 25% of PNC group had capture in all 3 (RSPV, RIPV, and carina) regions. There was no difference in the clinical characteristics between the groups with and without PNC. RF PVI caused no PNI in either group. High output pacing around the right pulmonary veins and the carina reveals that the phrenic nerve lies along a wide-area circumferential ablation trajectory in 30% of patients. Modification of ablation lines to avoid these sites may prevent phrenic nerve injury during RF PVI. © 2013 Wiley Periodicals, Inc.

A randomized pilot study of optimization of cardiac resynchronization therapy in sinus rhythm patients using a peak endocardial acceleration sensor vs. standard methods.

PubMed

Ritter, Philippe; Delnoy, Peter Paul H M; Padeletti, Luigi; Lunati, Maurizio; Naegele, Herbert; Borri-Brunetto, Alberto; Silvestre, Jorge

2012-09-01

Non-response rate to cardiac resynchronization therapy (CRT) might be decreased by optimizing device programming. The Clinical Evaluation on Advanced Resynchronization (CLEAR) study aimed to assess the effects of CRT with automatically optimized atrioventricular (AV) and interventricular (VV) delays, based on a Peak Endocardial Acceleration (PEA) signal system. This multicentre, single-blind study randomized patients in a 1 : 1 ratio to CRT optimized either automatically by the PEA-based system, or according to centres' usual practices, mostly by echocardiography. Patients had heart failure (HF) New York Heart Association (NYHA) functional class III/IV, left ventricular ejection fraction (LVEF) <35%, QRS duration >150 or >120 ms with mechanical dyssynchrony. Follow-up was 1 year. The primary endpoint was the proportion of patients who improved their condition at 1 year, based on a composite of all-cause death, HF hospitalizations, NYHA class, and quality of life. In all, 268 patients in sinus rhythm (63% men; mean age: 73.1 ± 9.9 years; mean NYHA: 3.0 ± 0.3; mean LVEF: 27.1 ± 8.1%; and mean QRS duration: 160.1 ± 22.0 ms) were included and 238 patients were randomized, 123 to PEA and 115 to the control group. At 1 year, 76% of patients assigned to PEA were classified as improved, vs. 62% in the control group (P= 0.0285). The percentage of patients with improved NYHA class was significantly (P= 0.0020) higher in the PEA group than in controls. Fatal and non-fatal adverse events were evenly distributed between the groups. PEA-based optimization of CRT in HF patients significantly increased the proportion of patients who improved with therapy, mainly through improved NYHA class, after 1 year of follow-up.

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

PubMed Central

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

2016-01-01

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

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

PubMed

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

2016-07-14

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

Noninvasive Localization of Accessory Pathways in Wolff-Parkinson-White Syndrome by Three-Dimensional Speckle Tracking Echocardiography.

PubMed

Ishizu, Tomoko; Seo, Yoshihiro; Igarashi, Miyako; Sekiguchi, Yukio; Machino-Ohtsuka, Tomoko; Ogawa, Kojiro; Kuroki, Kenji; Yamamoto, Masahiro; Nogami, Akihiko; Kawakami, Yasushi; Aonuma, Kazutaka

2016-06-01

We have developed a noninvasive isochrone activation imaging (AI) system with 3-dimensional (3D) speckle tracking echocardiography (STE), which allows visualization of the wavefront image of mechanical propagation of the accessory pathway (ACP) in Wolff-Parkinson-White syndrome. Patients with manifest Wolff-Parkinson-White syndrome were imaged in 3D-STE AI mode, which quantified the time from QRS onset to regional endocardial deformation. In 2 patients with left- and right-side ACP, we confirmed that intraoperative contact endocardial electric mapping and the 3D-STE AI system showed comparable images pre- and postablation. In normal heart assessment by 3D-echo AI, the earliest activation sites were found at the attachment of the papillary muscles in the left ventricle and midseptum in the right ventricle, and none showed earliest activation at the peri-atrioventricular valve annuli. An analyzer who was unaware of the clinical information assessed 39 ACP locations in 38 Wolff-Parkinson-White syndrome patients using 3D-STE. All showed abnormal perimitral or tricuspid annular activations, and the location of 34 ACP (87%) showed agreement with the successful ablation sites within a 2-o'clock range. Especially for left free wall ACP, 17/18 (94%) showed consistency with the ablation site within a 2 o'clock range. Among 15 ACP at the ventricular septum, 9 (60%) showed early local activation in both right and left sides of the septum. Isochrone AI with 3D-STE may be a promising noninvasive imaging tool to assess cardiac synchronized activation in normal hearts and detect abnormal breakthrough of mechanical activation from both atrioventricular annuli in Wolff-Parkinson-White syndrome. © 2016 American Heart Association, Inc.

The human ether-a-go-go-related gene (hERG) current inhibition selectively prolongs action potential of midmyocardial cells to augment transmural dispersion.

PubMed

Yasuda, C; Yasuda, S; Yamashita, H; Okada, J; Hisada, T; Sugiura, S

2015-08-01

The majority of drug induced arrhythmias are related to the prolongation of action potential duration following inhibition of rapidly activating delayed rectifier potassium current (I(Kr)) mediated by the hERG channel. However, for arrhythmias to develop and be sustained, not only the prolongation of action potential duration but also its transmural dispersion are required. Herein, we evaluated the effect of hERG inhibition on transmural dispersion of action potential duration using the action potential clamp technique that combined an in silico myocyte model with the actual I(Kr) measurement. Whole cell I(Kr) current was measured in Chinese hamster ovary cells stably expressing the hERG channel. The measured current was coupled with models of ventricular endocardial, M-, and epicardial cells to calculate the action potentials. Action potentials were evaluated under control condition and in the presence of 1, 10, or 100 μM disopyramide, an hERG inhibitor. Disopyramide dose-dependently increased the action potential durations of the three cell types. However, action potential duration of M-cells increased disproportionately at higher doses, and was significantly different from that of epicardial and endocardial cells (dispersion of repolarization). By contrast, the effects of disopyramide on peak I(Kr) and instantaneous current-voltage relation were similar in all cell types. Simulation study suggested that the reduced repolarization reserve of M-cell with smaller amount of slowly activating delayed rectifier potassium current levels off at longer action potential duration to make such differences. The action potential clamp technique is useful for studying the mechanism of arrhythmogenesis by hERG inhibition through the transmural dispersion of repolarization.

Long-term thresholds of nonsteroidal permanent pacing leads: a 5-year study.

PubMed

Gumbrielle, T P; Bourke, J P; Sinkovic, M; Tynan, M; Kittpawong, P; Gold, R G

1996-05-01

The present commercial market supports many nonsteroidal endocardial pacing leads of differing construction. In order to compare the performance of these configurations, we studied the long-term pacing properties of three representative lead types by randomized clinical trial in 99 patients undergoing a first elective VVI implant. Thirty-one patients received sintered platinum leads, 36 activated pyrolytic carbon leads, and 32 vitreous carbon leads. All received generators capable of noninvasive threshold testing. Acute sensing parameters were R wave amplitude and ST segment elevation measured from the endocardial electrogram. Noninvasive voltage thresholds were measured at implantation, 2 days, 1, 3, and 6 months, and yearly thereafter for 5 years. There were no significant differences between leads in pacing or sensing capabilities at implantation. All three demonstrated similar increases in thresholds, peaking at 1 month, then falling to a plateau by 6 months and did not vary significantly thereafter. There were no significant differences in thresholds between leads during 5 years of follow-up. The lowest mean threshold at 5 years was 0.93 V at 0.5 ms. This study suggests that: (1) although these lead types all perform well, none offers any particular clinical advantage over another; (2) the degree of early threshold peaking precludes immediate postimplant output reduction, but later thresholds are sufficiently low to enable reductions in pacing output; (3) safe low energy pacing requires greater attention to the lead-generator combinations; (4) data obtained at subsequent annual follow-up provided no additional useful clinical information to that obtained at 1 year; and (5) in the absence of other differences, cost can be the deciding factor in lead selection.

Beyond the Storm: Comparison of Clinical Factors, Arrhythmogenic Substrate, and Catheter Ablation Outcomes in Structural Heart Disease Patients With versus Those Without a History of Ventricular Tachycardia Storm.

PubMed

Kumar, Saurabh; Fujii, Akira; Kapur, Sunil; Romero, Jorge; Mehta, Nishaki K; Tanigawa, Shinichi; Epstein, Laurence M; Koplan, Bruce A; Michaud, Gregory F; John, Roy M; Stevenson, William G; Tedrow, Usha B

2017-01-01

Catheter ablation can be lifesaving in ventricular tachycardia (VT) storm, but the underlying substrate in patients with storm is not well characterized. We sought to compare the clinical factors, substrate, and outcomes differences in patients with sustained monomorphic VT who present for catheter ablation with VT storm versus those with a nonstorm presentation. Consecutive ischemic (ICM; n = 554) or nonischemic cardiomyopathy patients (NICM; n = 369) with a storm versus nonstorm presentation were studied (ICM storm 186; NICM storm 101). In ICM, storm compared with nonstorm patients had significantly lower left ventricular (LV) ejection fraction (EF), greater number of antiarrhythmic drug (AAD) failures, slower VTs, greater number of scarred LV segments, higher incidence of anterior, septal, and apical endocardial LV scar (all P < 0.05). However, outcomes in follow-up were similar (12-month ventricular arrhythmia [VA]-free survival: 51% vs. 52%, P = 0.6; survival free of death/transplant 75% vs. 87%, P = 0.7). In addition to the above differences, NICM storm patients were also older; however, the extent and distribution of scar was similar except for a higher incidence of lateral endocardial scar in storm patients (P = 0.05). VA-free survival (36% vs. 47%, P = 0.004) and survival free of death/transplant, however, were worse in NICM storm than nonstorm patients (72% vs. 88%, P = 0.001). NICM storm patients had worse VA-free survival than ICM storm patients. There are differences in clinical factors and scar patterns in patients undergoing VT ablation who present with VT storm versus those with a nonstorm presentation. Clinical outcomes are worse in NICM storm patients. © 2016 Wiley Periodicals, Inc.

Epicardial clip occlusion of the left atrial appendage during cardiac surgery provides optimal surgical results and long-term stability.

PubMed

Kurfirst, Vojtech; Mokrácek, Aleš; Canádyová, Júlia; Frána, Radim; Zeman, Petr

2017-07-01

Occlusion of the left atrial appendage (LAA) has become an integral and important part of the surgical treatment of atrial fibrillation. Different methods of surgical occlusion of the LAA have been associated with varying levels of short- and long-term success for closure. The purpose of this study was to evaluate long-term results of epicardial placement and endocardial occlusion in patients undergoing cardiac operative procedures. A total of 101 patients (average age 65.7 years) undergoing cardiac operative procedures with the epicardial AtriClip Exclusion System of the LAA were enrolled in the study. The AtriClip was placed via a sternotomy or a thoracotomy or from a thoracoscopic approach. Postoperative variables, such as thromboembolic events, clip stability and endocardial leakage around the device, were examined by transoesophageal echocardiography (TEE) and/or computed tomography. Perioperative clip implantation was achieved in 98% of patients. TEE and/or computed tomography conducted during the follow-up period, comprising 1873 patient-months with a mean duration of 18 ± 11 months, revealed no clip migration, no leakage around the device and no clot formation near the remnant cul-de-sac. During the follow-up period, 4 of the cardiac patients experienced transitory ischaemic attacks, whereas no patient experienced a cerebrovascular attack. The Epicardial AtriClip Exclusion System of the LAA appears to be a feasable and safe operative method with a high success rate. Long-term follow-up confirmed clip stability, complete occlussion of the LAA and absence of any atrial fibrilation-related thromboembolic events. These results need to be confirmed by a larger, multicentre study. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Myocardial Tbx20 regulates early atrioventricular canal formation and endocardial epithelial-mesenchymal transition via Bmp2

PubMed Central

Cai, Xiaoqiang; Nomura-Kitabayashi, Aya; Cai, Weibin; Yan, Jianyun; Christoffels, Vincent M.; Cai, Chen-Leng

2011-01-01

During early embryogenesis, the formation of the cardiac atrioventricular canal (AVC) facilitates the transition of the heart from a linear tube into a chambered organ. However, the genetic pathways underlying this developmental process are poorly understood. The T-box transcription factor Tbx20 is expressed predominantly in the AVC of early heart tube. It was shown that Tbx20 activates Nmyc1 and suppresses Tbx2 expression to promote proliferation and specification of the atrial and ventricular chambers, yet it is not known if Tbx20 is involved in early AVC development. Here, we report that mice lacking Tbx20 in the AVC myocardium fail to form the AVC constriction, and the endocardial epithelial-mesenchymal transition (EMT) is severely perturbed. Tbx20 maintains expression of a variety of genes, including Bmp2, Tbx3 and Hand1 in the AVC myocardium. Intriguingly, we found Bmp2 downstream genes involved in the EMT initiation are also downregulated. In addition, re-expression of Bmp2 in the AVC myocardium substantially rescues the EMT defects resulting from the lack of Tbx20, suggesting Bmp2 is one of the key downstream targets of Tbx20 in AVC development. Our data support a complex signaling network with Tbx20 suppressing Tbx2 in the AVC myocardium but also indirectly promoting Tbx2 expression through Bmp2. The spatiotemporal expression of Tbx2 in the AVC appears to be balanced between these two opposing signals. Overall, our study provides genetic evidence that Tbx20 has essential roles in regulating AVC development that coordinate early cardiac chamber formation. PMID:21983003

Myocardial Tbx20 regulates early atrioventricular canal formation and endocardial epithelial-mesenchymal transition via Bmp2.

PubMed

Cai, Xiaoqiang; Nomura-Kitabayashi, Aya; Cai, Weibin; Yan, Jianyun; Christoffels, Vincent M; Cai, Chen-Leng

2011-12-15

During early embryogenesis, the formation of the cardiac atrioventricular canal (AVC) facilitates the transition of the heart from a linear tube into a chambered organ. However, the genetic pathways underlying this developmental process are poorly understood. The T-box transcription factor Tbx20 is expressed predominantly in the AVC of early heart tube. It was shown that Tbx20 activates Nmyc1 and suppresses Tbx2 expression to promote proliferation and specification of the atrial and ventricular chambers, yet it is not known if Tbx20 is involved in early AVC development. Here, we report that mice lacking Tbx20 in the AVC myocardium fail to form the AVC constriction, and the endocardial epithelial-mesenchymal transition (EMT) is severely perturbed. Tbx20 maintains expression of a variety of genes, including Bmp2, Tbx3 and Hand1 in the AVC myocardium. Intriguingly, we found Bmp2 downstream genes involved in the EMT initiation are also downregulated. In addition, re-expression of Bmp2 in the AVC myocardium substantially rescues the EMT defects resulting from the lack of Tbx20, suggesting Bmp2 is one of the key downstream targets of Tbx20 in AVC development. Our data support a complex signaling network with Tbx20 suppressing Tbx2 in the AVC myocardium but also indirectly promoting Tbx2 expression through Bmp2. The spatiotemporal expression of Tbx2 in the AVC appears to be balanced between these two opposing signals. Overall, our study provides genetic evidence that Tbx20 has essential roles in regulating AVC development that coordinate early cardiac chamber formation. Copyright © 2011 Elsevier Inc. All rights reserved.

Accurate means of detecting and characterizing abnormal patterns of ventricular activation by phase image analysis

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

Botvinick, E.H.; Frais, M.A.; Shosa, D.W.

1982-08-01

The ability of scintigraphic phase image analysis to characterize patterns of abnormal ventricular activation was investigated. The pattern of phase distribution and sequential phase changes over both right and left ventricular regions of interest were evaluated in 16 patients with normal electrical activation and wall motion and compared with those in 8 patients with an artificial pacemaker and 4 patients with sinus rhythm with the Wolff-Parkinson-White syndrome and delta waves. Normally, the site of earliest phase angle was seen at the base of the interventricular septum, with sequential change affecting the body of the septum and the cardiac apex andmore » then spreading laterally to involve the body of both ventricles. The site of earliest phase angle was located at the apex of the right ventricle in seven patients with a right ventricular endocardial pacemaker and on the lateral left ventricular wall in one patient with a left ventricular epicardial pacemaker. In each case the site corresponded exactly to the position of the pacing electrode as seen on posteroanterior and left lateral chest X-ray films, and sequential phase changes spread from the initial focus to affect both ventricles. In each of the patients with the Wolff-Parkinson-White syndrome, the site of earliest ventricular phase angle was located, and it corresponded exactly to the site of the bypass tract as determined by endocardial mapping. In this way, four bypass pathways, two posterior left paraseptal, one left lateral and one right lateral, were correctly localized scintigraphically. On the basis of the sequence of mechanical contraction, phase image analysis provides an accurate noninvasive method of detecting abnormal foci of ventricular activation.« less

Long-Term Outcome With Catheter Ablation of Ventricular Tachycardia in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy.

PubMed

Santangeli, Pasquale; Zado, Erica S; Supple, Gregory E; Haqqani, Haris M; Garcia, Fermin C; Tschabrunn, Cory M; Callans, David J; Lin, David; Dixit, Sanjay; Hutchinson, Mathew D; Riley, Michael P; Marchlinski, Francis E

2015-12-01

Catheter ablation of ventricular tachycardia (VT) in arrhythmogenic right ventricular cardiomyopathy improves short-term VT-free survival. We sought to determine the long-term outcomes of VT control and need for antiarrhythmic drug therapy after endocardial (ENDO) and adjuvant epicardial (EPI) substrate modification in patients with arrhythmogenic right ventricular cardiomyopathy. We examined 62 consecutive patients with Task Force criteria for arrhythmogenic right ventricular cardiomyopathy referred for VT ablation with a minimum follow-up of 1 year. Catheter ablation was guided by activation/entrainment mapping for tolerated VT and pacemapping/targeting of abnormal substrate for unmappable VT. Adjuvant EPI ablation was performed when recurrent VT or persistent inducibility after ENDO-only ablation. Endocardial plus adjuvant EPI ablation was performed in 39 (63%) patients, including 13 who crossed over to ENDO-EPI after VT recurrence during follow-up, after ENDO-only ablation. Before ablation, 54 of 62 patients failed a mean of 2.4 antiarrhythmic drugs, including amiodarone in 29 (47%) patients. During follow-up of 56±44 months after the last ablation, VT-free survival was 71% with only a single VT episode in additional 9 patients (15%). At last follow-up, 39 (64%) patients were only on β-blockers or no treatment, 21 were on class 1 or 3 antiarrhythmic drugs (11 for atrial arrhythmias), and 2 were on amiodarone as a bridge to heart transplantation. The long-term outcome after ENDO and adjuvant EPI substrate ablation of VT in arrhythmogenic right ventricular cardiomyopathy is good. Most patients have complete VT control without amiodarone therapy and limited need for antiarrhythmic drugs. © 2015 American Heart Association, Inc.

Lagrangian displacement tracking using a polar grid between endocardial and epicardial contours for cardiac strain imaging.

PubMed

Ma, Chi; Varghese, Tomy

2012-04-01

Accurate cardiac deformation analysis for cardiac displacement and strain imaging over time requires Lagrangian description of deformation of myocardial tissue structures. Failure to couple the estimated displacement and strain information with the correct myocardial tissue structures will lead to erroneous result in the displacement and strain distribution over time. Lagrangian based tracking in this paper divides the tissue structure into a fixed number of pixels whose deformation is tracked over the cardiac cycle. An algorithm that utilizes a polar-grid generated between the estimated endocardial and epicardial contours for cardiac short axis images is proposed to ensure Lagrangian description of the pixels. Displacement estimates from consecutive radiofrequency frames were then mapped onto the polar grid to obtain a distribution of the actual displacement that is mapped to the polar grid over time. A finite element based canine heart model coupled with an ultrasound simulation program was used to verify this approach. Segmental analysis of the accumulated displacement and strain over a cardiac cycle demonstrate excellent agreement between the ideal result obtained directly from the finite element model and our Lagrangian approach to strain estimation. Traditional Eulerian based estimation results, on the other hand, show significant deviation from the ideal result. An in vivo comparison of the displacement and strain estimated using parasternal short axis views is also presented. Lagrangian displacement tracking using a polar grid provides accurate tracking of myocardial deformation demonstrated using both finite element and in vivo radiofrequency data acquired on a volunteer. In addition to the cardiac application, this approach can also be utilized for transverse scans of arteries, where a polar grid can be generated between the contours delineating the outer and inner wall of the vessels from the blood flowing though the vessel.

Additive Prognostic Value of Left Ventricular Systolic Dysfunction in a Population-Based Cohort.

PubMed

Kuznetsova, Tatiana; Cauwenberghs, Nicholas; Knez, Judita; Yang, Wen-Yi; Herbots, Lieven; D'hooge, Jan; Haddad, Francois; Thijs, Lutgarde; Voigt, Jens-Uwe; Staessen, Jan A

2016-07-01

Techniques of 2-dimensional speckle tracking enable the measurement of myocardial deformation (strain) during systole. Recent clinical studies explored the prognostic role of left ventricular global longitudinal strain (GLS). However, there are few data on the association between cardiovascular outcome and GLS in the community. Therefore, we hypothesized that GLS contains additive prognostic information over and beyond traditional cardiovascular risk factors in a large, population-based cohort. We measured GLS by 2-dimensional speckle tracking in the apical 4-chamber view in 791 participants (mean age 50.9 years). We calculated multivariable adjusted hazard ratios for midwall, endocardial, and epicardial GLS, while accounting for family cluster and cardiovascular risk factors. Median follow-up was 7.9 years (5th to 95th percentile, 3.7-9.6). In continuous analysis, with adjustments applied for covariables, midwall, endocardial, and epicardial GLS were significant predictors of fatal and nonfatal cardiovascular (n=96; P<0.0001) and cardiac events (n=68; P≤0.001). In the sex-specific low quartile of midwall GLS (<18.8% in women and <17.4% in men), the risk was significantly higher than the average population risk for cardiovascular (128%, P<0.0001) and cardiac (94%, P=0.0007) events. We also noticed that the risk for cardiovascular events increased with increasing number of left ventricular abnormalities, such as low GLS, diastolic dysfunction, and hypertrophy (log-rank P<0.0001). Low GLS measured by 2-dimensional speckle tracking predicts future cardiovascular events independent of conventional risk factors. Left ventricular midwall strain represents a simple echocardiographic measure, which might be used for assessing cardiovascular risk in a population-based cohort. © 2016 American Heart Association, Inc.

Contrast and harmonic imaging improves accuracy and efficiency of novice readers for dobutamine stress echocardiography

NASA Technical Reports Server (NTRS)

Vlassak, Irmien; Rubin, David N.; Odabashian, Jill A.; Garcia, Mario J.; King, Lisa M.; Lin, Steve S.; Drinko, Jeanne K.; Morehead, Annitta J.; Prior, David L.; Asher, Craig R.;

A null mutation of Hhex results in abnormal cardiac development, defective vasculogenesis and elevated Vegfa levels.

PubMed

Hallaq, Haifa; Pinter, Emese; Enciso, Josephine; McGrath, James; Zeiss, Caroline; Brueckner, Martina; Madri, Joseph; Jacobs, Harris C; Wilson, Christine M; Vasavada, Hemaxi; Jiang, Xiaobing; Bogue, Clifford W

2004-10-01

The homeobox gene Hhex has recently been shown to be essential for normal liver, thyroid and forebrain development. Hhex(-/-) mice die by mid-gestation (E14.5) and the cause of their early demise remains unclear. Because Hhex is expressed in the developing blood islands at E7.0 in the endothelium of the developing vasculature and heart at E9.0-9.5, and in the ventral foregut endoderm at E8.5-9.0, it has been postulated to play a critical role in heart and vascular development. We show here, for the first time, that a null mutation of Hhex results in striking abnormalities of cardiac and vascular development which include: (1) defective vasculogenesis, (2) hypoplasia of the right ventricle, (3) overabundant endocardial cushions accompanied by ventricular septal defects, outflow tract abnormalities and atrio-ventricular (AV) valve dysplasia and (4) aberrant development of the compact myocardium. The dramatic enlargement of the endocardial cushions in the absence of Hhex is due to decreased apoptosis and dysregulated epithelial-mesenchymal transformation (EMT). Interestingly, vascular endothelial growth factor A (Vegfa) levels in the hearts of Hhex(-/-) mice were elevated as much as three-fold between E9.5 and E11.5, and treatment of cultured Hhex(-/-) AV explants with truncated soluble Vegfa receptor 1, sFlt-1, an inhibitor of Vegf signaling, completely abolished the excessive epithelial-mesenchymal transformation seen in the absence of Hhex. Therefore, Hhex expression in the ventral foregut endoderm and/or the endothelium is necessary for normal cardiovascular development in vivo, and one function of Hhex is to repress Vegfa levels during development.

Malformation of the canine mitral valve complex.

PubMed

Litu, S K; Tilley, L P

1975-09-15

Twenty-nine dogs, including 13 Great Danes and 5 German Shepherd Dogs and averaging 7.3 months age, were diagnosed clinically and radiographically as having mitral regurgitation. Alterations of the mitral valve complex included enlarged anulus; short thick leaflets, with an occasional cleft; short and stout or long and thin chordae tendineae; upward malposition of atrophic or hypertrophic papillary muscles; insertion of one papillary muscle directly into one or both leaflets; and diffuse endocardial fibrosis, occasionally with jet lesions in te left atrium. Other cardiac anomalies included dysplasia of the tricuspid valve (5 dogs), patent ductus afteriosus (2 dogs), aortic stenosis (2 dogs), and ventricular septal defect (1 dog).

[Fetal atrioventricular septal defect associated with Patau and Edwards syndromes, as well as trisomy 22].

PubMed

Cesko, I; Hajdú, J; Marton, T; Tóth-Pál, E; Papp, C; Papp, Z

1998-05-03

The atrioventricular septal defect is usually associated with trisomy 21 and it may be observed in the heterotaxia syndromes. Atrioventricular septal defect may be associated with 8p deletion. There are reported cases of familial atrioventricular septal defect. Atrioventicular septal defect is rarely associated with other chromosomal abnormalities. We are reporting three unusual cases of atrioventricular septal defect that were associated with trisomy 13, 18 and 22. This association may be due to effect of genetic loci on the 13, 18 and 22 chromosome which could play the role in the development and fusion of endocardial cushion and atrioventricular septal defect.

Accelerated idioventricular rhythm requiring catheter ablation in a child: The dark side of a benign arrhythmia.

PubMed

Errahmouni, A; Bun, S-S; Latcu, D G; Tazi-Mezalek, A; Saoudi, N

2017-11-01

A 12 year-old boy, with no history of cardiac disease, was referred to our department for evaluation of an incessant accelerated idioventricular rhythm (AIVR) complicated with severe left ventricular (LV) dysfunction and cardiogenic shock. Extensive diagnostic work-up failed to reveal any structural heart disease. During electrophysiological study, AIVR originated from the right ventricular endocardial anterior wall and was successfully ablated using remote magnetic navigation. LV function showed complete recovery four weeks after the procedure. This case highlights a life-threatening evolution of an arrhythmia generally presented as a benign entity in children. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

An E/e' ratio on echocardiography predicts the existence of left atrial low-voltage areas and poor outcomes after catheter ablation for atrial fibrillation.

PubMed

Masuda, Masaharu; Fujita, Masashi; Iida, Osamu; Okamoto, Shin; Ishihara, Takayuki; Nanto, Kiyonori; Kanda, Takashi; Sunaga, Akihiro; Tsujimura, Takuya; Matsuda, Yasuhiro; Ohashi, Takuya; Uematsu, Masaaki

2018-05-01

An elevated left atrial pressure has been reported to play an important role in the development of atrial remodelling in atrial fibrillation (AF) patients. The study aimed at elucidating the association between the diastolic early transmitral flow velocity/mitral annular velocity (E/e', a non-invasive surrogate of left atrial pressure) and left atrial low-voltage-area existence, and the prognostic impact of the E/e' on procedural outcomes in patients undergoing AF ablation. Total of 215 consecutive patients were divided into 3 groups based on the estimated left atrial pressure: normal (E/e' < 8.0, n = 58), undetermined (E/e' = 8.0-14.0, n = 114), and elevated (E/e' > 14.0, n = 43). Left atrial endocardial voltage mapping was performed following pulmonary vein isolation. Patients with a high E/e' more frequently had low-voltage areas (E/e' < 8.0, 31%, E/e' = 8.0-14.0, 35%; E/e' > 14.0, 67%; P = 0.0001). After adjusting for other correlates, a high E/e' was an independent predictor of low-voltage-area existence (HR = 1.11, 95% CI = 1.02-1.21, P = 0.017). During a mean follow-up period of 12 ± 6 months, recurrent atrial tachyarrhythmias occurred in 22 (10%) patients after multiple (1.4 ± 0.5) procedures. Patients with an E/e' > 14 had more frequent recurrent atrial tachyarrhythmias after multiple ablation procedures than those with an E/e' ≤ 14 (23% vs. 7%, P = 0.001). A high E/e' obtained by pre-ablation echocardiography was associated with a left atrial arrhythmogenic substrate in patients undergoing AF ablation. Furthermore, a high E/e' predicted poor procedural outcomes after pulmonary vein isolation.

Chymase inhibition prevents fibronectin and myofibrillar loss and improves cardiomyocyte function and LV torsion angle in dogs with isolated mitral regurgitation.

PubMed

Pat, Betty; Chen, Yuanwen; Killingsworth, Cheryl; Gladden, James D; Shi, Ke; Zheng, Junying; Powell, Pamela C; Walcott, Greg; Ahmed, Mustafa I; Gupta, Himanshu; Desai, Ravi; Wei, Chih-Chang; Hase, Naoki; Kobayashi, Tsunefumi; Sabri, Abdelkarim; Granzier, Henk; Denney, Thomas; Tillson, Michael; Dillon, A Ray; Husain, Ahsan; Dell'italia, Louis J

2010-10-12

The left ventricular (LV) dilatation of isolated mitral regurgitation (MR) is associated with an increase in chymase and a decrease in interstitial collagen and extracellular matrix. In addition to profibrotic effects, chymase has significant antifibrotic actions because it activates matrix metalloproteinases and kallikrein and degrades fibronectin. Thus, we hypothesize that chymase inhibitor (CI) will attenuate extracellular matrix loss and LV remodeling in MR. We studied dogs with 4 months of untreated MR (MR; n=9) or MR treated with CI (MR+CI; n=8). Cine MRI demonstrated a >40% increase in LV end-diastolic volume in both groups, consistent with a failure of CI to improve a 25% decrease in interstitial collagen in MR. However, LV cardiomyocyte fractional shortening was decreased in MR versus normal dogs (3.71±0.24% versus 4.81±0.31%; P<0.05) and normalized in MR+CI dogs (4.85±0.44%). MRI with tissue tagging demonstrated an increase in LV torsion angle in MR+CI versus MR dogs. CI normalized the significant decrease in fibronectin and FAK phosphorylation and prevented cardiomyocyte myofibrillar degeneration in MR dogs. In addition, total titin and its stiffer isoform were increased in the LV epicardium and paralleled the changes in fibronectin and FAK phosphorylation in MR+CI dogs. These results suggest that chymase disrupts cell surface-fibronectin connections and FAK phosphorylation that can adversely affect cardiomyocyte myofibrillar structure and function. The greater effect of CI on epicardial versus endocardial titin and noncollagen cell surface proteins may be responsible for the increase in torsion angle in chronic MR.

The normal variants in the left bundle branch system.

PubMed

Elizari, M V

This article reviewed the main anatomic and physiopathological aspects of the left bundle branch from its origin in the His bundle and its intraventricular distribution on the left endocardial surface. The results are based on the relevant literature and on personal observations executed on 206 hearts distributed as follows: 67 dogs, 60 humans, 45 sheep, 22 pigs, 10 cows, 2 monkeys, 1 guanaco, and 1 sea lion. The main anatomical features of the His-Purkinje conducting system may be summarized as follows: The bundle of His is composed by two segments: the penetrating and branching portions. LBB originates in the branching portion located underneath the membranous septum. There is no true bifurcation of the bundle of His in a human heart. Short after its origin the LBB gives rise to its two main fascicles, anterior and posterior, both heading the anterior and posterior papillary muscles, respectively. The anterior division is thinner and longer than the posterior one. The RBB and the most anterior fibers of the LBB arise at the end of the branching portion. In some cases a well-defined left septal fascicle can be identified, usually arising from the posterior division. Each division gives off small fibers and false tendons crossing the left ventricular cavity connecting the papillary between them or the papillary muscles with the septal surface. From each division of the LBB, their corresponding Purkinje networks emerge covering the subendocardium of the septum and the free wall of the left ventricles. There are critical relationships of the proximal segments of the His-Purkinje system with the surrounding cardiac structures whose pathologic processes may damage the conducting tissue. Copyright © 2017 Elsevier Inc. All rights reserved.

Use of New Imaging CARTO® Segmentation Module Software to Facilitate Ablation of Ventricular Arrhythmias.

PubMed

Tovia-Brodie, Oholi; Belhassen, Bernard; Glick, Aharon; Shmilovich, Haim; Aviram, Galit; Rosso, Raphael; Michowitz, Yoav

2017-02-01

A new imaging software (CARTO® Segmentation Module, Biosense Webster) allows preprocedural 3-D reconstruction of all heart chambers based on cardiac CT. We describe our initial experience with the new module during ablation of ventricular arrhythmias. Eighteen consecutive patients with idiopathic ventricular arrhythmias or ischemic ventricular tachycardia (VT) were studied. In the latter group, a combined endocardial and epicardial ablation was performed. Of the 14 patients with idiopathic arrhythmias, 12 were ablated in the outflow tract (OT), 1 in the midseptal left ventricle, and 1 at the left posterior fascicular area; acute successful ablation was achieved in 11 (78.6%) patients. The procedure was discontinued due to close proximity of the arrhythmia origin to the coronary arteries (CA) in 2 patients. Acute successful uncomplicated ablation was achieved in all 4 patients with ischemic VT. During ablation in the coronary cusps commissures, the CARTO® Segmentation Module accurately defined the cusps anatomy. The precise anatomic location provided by the module assisted in successfully ablating when information from activation mapping was not optimal, by ablating at the opposite side of the cusps. In addition, by demonstrating the precise location of the CA, it allowed safe ablation of arrhythmias that originated in close proximity to the CA both in the OT area and the epicardium, eliminating the need for repeat angiography. The CARTO® Segmentation Module is useful for accurate definition of the exact anatomic location of ventricular arrhythmias and for safely ablating them especially in close proximity to the CA. © 2016 Wiley Periodicals, Inc.

Thermal distribution of microwave antenna for atrial fibrillation catheter ablation.

PubMed

Zhang, Huijuan; Nan, Qun; Liu, Youjun

2013-09-01

The aim of this study is to investigate the effects of ablation parameters on thermal distribution during microwave atrial fibrillation catheter ablation, such as ablation time, ablation power, blood condition and antenna placement, and give proper ablative parameters to realise transmural ablation. In this paper, simplified 3D antenna-myocardium-blood finite element method models were built to simulate the endocardial ablation operation. Thermal distribution was obtained based on the coupled electromagnetic-thermal analysis. Under different antenna placement conditions and different microwave power inputs within 60 s, the lesion dimensions (maximum depth, maximum width) of the ablation zones were analysed. The ablation width and depth increased with the ablation time. The increase rate significantly slowed down after 10 s. The maximum temperature was located in 1 mm under the antenna tip when perpendicular to the endocardium, while 1.5 mm away from the antenna axis and 26 mm along the antenna (with antenna length about 30 mm) in the myocardium when parallel to the endocardium. The maximum temperature in the ablated area decreased and the effective ablation area (with the temperature raised to 50°C) shifted deeper into the myocardium due to the blood cooling. The research validated that the microwave antenna can provide continuous long and linear lesions for the treatment of atrial fibrillation. The dimensions of the created lesion widths were all larger than those of the depths. It is easy for the microwave antenna to produce transmural lesions for an atrial wall thickness of 2-6 mm by adjusting the applied power and ablation time.

The roles of mid-myocardial and epicardial cells in T-wave alternans development: a simulation study.

PubMed

Janusek, D; Svehlikova, J; Zelinka, J; Weigl, W; Zaczek, R; Opolski, G; Tysler, M; Maniewski, R

2018-05-08

The occurrence of T-wave alternans in electrocardiographic signals was recently linked to susceptibility to ventricular arrhythmias and sudden cardiac death. Thus, by detecting and comprehending the origins of T-wave alternans, it might be possible to prevent such events. Here, we simulated T-wave alternans in a computer-generated human heart model by modulating the action potential duration and amplitude during the first part of the repolarization phase. We hypothesized that changes in the intracardiac alternans patterns of action potential properties would differentially influence T-wave alternans measurements at the body surface. Specifically, changes were simulated globally in the whole left and right ventricles to simulate concordant T-wave alternans, and locally in selected regions to simulate discordant and regional discordant, hereinafter referred to as "regional", T-wave alternans. Body surface potential maps and 12-lead electrocardiographic signals were then computed. In depth discrimination, the influence of epicardial layers on T-wave alternans development was significantly higher than that of mid-myocardial cells. Meanwhile, spatial discrimination revealed that discordant and regional action potential property changes had a higher influence on T-wave alternans amplitude than concordant changes. Notably, varying T-wave alternans sources yielded distinct body surface potential map patterns for T-wave alternans amplitude, which can be used for location of regions within hearts exhibiting impaired repolarization. The highest ability for T-wave alternans detection was achieved in lead V1. Ultimately, we proposed new parameters Vector Magnitude Alternans and Vector Angle Alternans, with higher ability for T-wave alternans detection when using multi-lead electrocardiographic signals processing than for single leads. Finally, QT alternans was found to be associated with the process of T-wave alternans generation. The distributions of the body surface T-wave alternans amplitude have been shown to have unique patterns depending on the type of alternans (concordant, discordant or regional) and the location of the disturbance in the heart. The influence of epicardial cells on T-wave alternans development is significantly higher than that of mid-myocardial cells, among which the sub-endocardial layer exerted the highest influence. QT interval alternans is identified as a phenomenon that correlate with T-wave alternans.

Characterisation of a monoclonal antibody detecting Atlantic salmon endothelial and red blood cells, and its association with the infectious salmon anaemia virus cell receptor.

PubMed

Aamelfot, Maria; Weli, Simon C; Dale, Ole B; Koppang, Erling O; Falk, Knut

2013-05-01

Endothelial cells (ECs) line the luminal surfaces of the cardiovascular system and play an important role in cardiovascular functions such as regulation of haemostasis and vasomotor tone. A number of fish and mammalian viruses target these cells in the course of their infection. Infectious salmon anaemia virus (ISAV) attacks ECs and red blood cells (RBCs) of farmed Atlantic salmon (Salmo salar L.), producing the severe disease of infectious salmon anaemia (ISA). The investigation of ISA has up to now been hampered by the lack of a functional marker for ECs in Atlantic salmon in situ. In this study, we report the characterisation and use of a novel monoclonal antibody (MAb) detecting Atlantic salmon ECs (e.g. vessel endothelium, endocardial cells and scavenger ECs) and RBCs. The antibody can be used with immunohistochemistry, IFAT and on Western blots. It appears that the epitope recognised by the antibody is associated with the ISAV cellular receptor. Besides being a tool to identify ECs in situ, it could be useful in further studies of the pathogenicity of ISA. Finally, the detection of an epitope shared by ECs and RBCs agrees with recent findings that these cells share a common origin, thus the MAb can potentially be used to study the ontogeny of these cells in Atlantic salmon. © 2013 Anatomical Society.

Denoising and 4D visualization of OCT images

PubMed Central

Gargesha, Madhusudhana; Jenkins, Michael W.; Rollins, Andrew M.; Wilson, David L.

2009-01-01

We are using Optical Coherence Tomography (OCT) to image structure and function of the developing embryonic heart in avian models. Fast OCT imaging produces very large 3D (2D + time) and 4D (3D volumes + time) data sets, which greatly challenge ones ability to visualize results. Noise in OCT images poses additional challenges. We created an algorithm with a quick, data set specific optimization for reduction of both shot and speckle noise and applied it to 3D visualization and image segmentation in OCT. When compared to baseline algorithms (median, Wiener, orthogonal wavelet, basic non-orthogonal wavelet), a panel of experts judged the new algorithm to give much improved volume renderings concerning both noise and 3D visualization. Specifically, the algorithm provided a better visualization of the myocardial and endocardial surfaces, and the interaction of the embryonic heart tube with surrounding tissue. Quantitative evaluation using an image quality figure of merit also indicated superiority of the new algorithm. Noise reduction aided semi-automatic 2D image segmentation, as quantitatively evaluated using a contour distance measure with respect to an expert segmented contour. In conclusion, the noise reduction algorithm should be quite useful for visualization and quantitative measurements (e.g., heart volume, stroke volume, contraction velocity, etc.) in OCT embryo images. With its semi-automatic, data set specific optimization, we believe that the algorithm can be applied to OCT images from other applications. PMID:18679509

Phrenic nerve protection via packing of gauze into the pericardial space during ablation of cristal atrial tachycardia in a child.

PubMed

Takahashi, Kazuhiro; Fuchigami, Tai; Nabeshima, Taisuke; Sashinami, Arata; Nakayashiro, Mami

2016-03-01

The success of catheter ablation of focal atrial tachycardia is limited by possible collateral damage to the phrenic nerve. Protection of the phrenic nerve is required. Here we present a case of a 9-year-old girl having a history of an unsuccessful catheter ablation of a focal atrial tachycardia near the crista terminalis (because of proximity of the phrenic nerve) who underwent a successful ablation by means of a novel technique for phrenic nerve protection: packing of gauze into the pericardial space. This method is a viable approach for patients with a failed endocardial ablation due to the proximity of the phrenic nerve.

Echocardiographic Changes in Eosinophilic Endocarditis Induced by Churg-Strauss Syndrome.

PubMed

Masaki, Nobuyuki; Issiki, Ami; Kirimura, Masato; Kamiyama, Tetsuo; Sasaki, Osamu; Ito, Hiroyuki; Maruyama, Yoshiaki; Nishioka, Toshihiko

Eosinophilic myocarditis may be accompanied by Churg-Strauss syndrome (CSS). We report a case of CSS that was accompanied by myocardial changes in the early stage. A 71-year-old woman complained of mild chest pain at rest, but routine echocardiography did not reveal any endocardial abnormalities. Four months later, the patient was hospitalized due to congestive heart failure with neuropathy of both upper extremities. A diagnosis of eosinophilic myocarditis was made based on the patient's laboratory results and the presence of mural thrombus. This case illustrates that, although early eosinophilic myocarditis is an important differential diagnosis in patients with chest pain, it may be difficult to identify in without an apparent mural thrombus.

Echocardiographic Changes in Eosinophilic Endocarditis Induced by Churg-Strauss Syndrome

PubMed Central

Masaki, Nobuyuki; Issiki, Ami; Kirimura, Masato; Kamiyama, Tetsuo; Sasaki, Osamu; Ito, Hiroyuki; Maruyama, Yoshiaki; Nishioka, Toshihiko

2016-01-01

Eosinophilic myocarditis may be accompanied by Churg-Strauss syndrome (CSS). We report a case of CSS that was accompanied by myocardial changes in the early stage. A 71-year-old woman complained of mild chest pain at rest, but routine echocardiography did not reveal any endocardial abnormalities. Four months later, the patient was hospitalized due to congestive heart failure with neuropathy of both upper extremities. A diagnosis of eosinophilic myocarditis was made based on the patient's laboratory results and the presence of mural thrombus. This case illustrates that, although early eosinophilic myocarditis is an important differential diagnosis in patients with chest pain, it may be difficult to identify in without an apparent mural thrombus. PMID:27725542

[Localization of substance P- and FMRFamide-like immunoreactivity in the atrium of the snail Achatina fulica].

PubMed

Shabel'nikov, S V; Bystrova, O A; Martynova, M G

2008-01-01

By immunohistochemical and immunocytochemical methods localization of Substanse P (SP) and FMRFamide in the atrium of the snail Achatina fulica was investigated. Nerve fibers innervating the snail atrium contact tightly with the granular cells (GC) situated between muscle and endocardial cells, forming neuroendocrine units. Both neuromediators were found in the cells of the neuroendocrine units. By immunohistochemistry SP- and FMRFamide-immunoreactive material was revealed in the granules of the atrial GC. Elecrtonmicroscopical immunocytochemistry has confirmed the presence of SP- and FMRFamide-immunoreactive material in the granules of the GC and shown their presence in the neurosecretory granules of the nerve endings contacting both the atrial GC and cardiomyocytes.

Contrast-enhanced sonography in pediatrics.

PubMed

McCarville, M Beth

2011-05-01

Microbubble US contrast agents are composed of an outer shell of protein, phospholipid or polymer that encase air or perfluorocarbon gas. These contrast agents have been widely used in adult cardiology patients to improve endocardial border delineation and have been proved safe and well tolerated in this patient population. There is also a growing body of literature elucidating the value of contrast-enhanced sonography to distinguish benign from malignant liver lesions in adults and to characterize non-hepatic adult malignancies. Because these agents have not been approved for pediatric use in many countries, less is known of the value of contrast-enhanced sonography in children. In this review I will discuss several proven and potential pediatric applications of contrast-enhanced sonography.

Global Bi-ventricular endocardial distribution of activation rate during long duration ventricular fibrillation in normal and heart failure canines.

PubMed

Luo, Qingzhi; Jin, Qi; Zhang, Ning; Han, Yanxin; Wang, Yilong; Huang, Shangwei; Lin, Changjian; Ling, Tianyou; Chen, Kang; Pan, Wenqi; Wu, Liqun

2017-04-13

The objective of this study was to detect differences in the distribution of the left and right ventricle (LV & RV) activation rate (AR) during short-duration ventricular fibrillation (SDVF, <1 min) and long-duration ventricular fibrillation VF (LDVF, >1 min) in normal and heart failure (HF) canine hearts. Ventricular fibrillation (VF) was electrically induced in six healthy dogs (control group) and six dogs with right ventricular pacing-induced congestive HF (HF group). Two 64-electrode basket catheters deployed in the LV and RV were used for global endocardium electrical mapping. The AR of VF was estimated by fast Fourier transform analysis from each electrode. In the control group, the LV was activated faster than the RV in the first 20 s, after which there was no detectable difference in the AR between them. When analyzing the distribution of the AR within the bi-ventricles at 3 min of LDVF, the posterior LV was activated fastest, while the anterior was slowest. In the HF group, a detectable AR gradient existed between the two ventricles within 3 min of VF, with the LV activating more quickly than the RV. When analyzing the distribution of the AR within the bi-ventricles at 3 min of LDVF, the septum of the LV was activated fastest, while the anterior was activated slowest. A global bi-ventricular endocardial AR gradient existed within the first 20 s of VF but disappeared in the LDVF in healthy hearts. However, the AR gradient was always observed in both SDVF and LDVF in HF hearts. The findings of this study suggest that LDVF in HF hearts can be maintained differently from normal hearts, which accordingly should lead to the development of different management strategies for LDVF resuscitation.

Development and evaluation of a semiautomatic segmentation method for the estimation of LV parameters on cine MR images

NASA Astrophysics Data System (ADS)

Mazonakis, Michalis; Grinias, Elias; Pagonidis, Konstantin; Tziritas, George; Damilakis, John

2010-02-01

The purpose of this study was to develop and evaluate a semiautomatic method for left ventricular (LV) segmentation on cine MR images and subsequent estimation of cardiac parameters. The study group comprised cardiac MR examinations of 18 consecutive patients with known or suspected coronary artery disease. The new method allowed the automatic detection of the LV endocardial and epicardial boundaries on each short-axis cine MR image using a Bayesian flooding segmentation algorithm and weighted least-squares B-splines minimization. Manual editing of the automatic contours could be performed for unsatisfactory segmentation results. The end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF) and LV mass estimated by the new method were compared with the reference values obtained by manually tracing the LV cavity borders. The reproducibility of the new method was determined using data from two independent observers. The mean number of endocardial and epicardial outlines not requiring any manual adjustment was more than 80% and 76% of the total contour number per study, respectively. The mean segmentation time including the required manual corrections was 2.3 ± 0.7 min per patient. LV volumes estimated by the semiautomatic method were significantly lower than those by manual tracing (P < 0.05), whereas no difference was found for EF and LV mass (P > 0.05). LV indices estimated by the two methods were well correlated (r >= 0.80). The mean difference between manual and semiautomatic method for estimating EDV, ESV, EF and LV mass was 6.1 ± 7.2 ml, 3.0 ± 5.2 ml, -0.6 ± 4.3% and -6.2 ± 12.2 g, respectively. The intraobserver and interobserver variability associated with the semiautomatic determination of LV indices was 0.5-1.2% and 0.8-3.9%, respectively. The estimation of LV parameters with the new semiautomatic segmentation method is technically feasible, highly reproducible and time effective.

Transmural heterogeneity of cellular level power output is reduced in human heart failure.

PubMed

Haynes, Premi; Nava, Kristofer E; Lawson, Benjamin A; Chung, Charles S; Mitov, Mihail I; Campbell, Stuart G; Stromberg, Arnold J; Sadayappan, Sakthivel; Bonnell, Mark R; Hoopes, Charles W; Campbell, Kenneth S

2014-07-01

Heart failure is associated with pump dysfunction and remodeling but it is not yet known if the condition affects different transmural regions of the heart in the same way. We tested the hypotheses that the left ventricles of non-failing human hearts exhibit transmural heterogeneity of cellular level contractile properties, and that heart failure produces transmural region-specific changes in contractile function. Permeabilized samples were prepared from the sub-epicardial, mid-myocardial, and sub-endocardial regions of the left ventricular free wall of non-failing (n=6) and failing (n=10) human hearts. Power, an in vitro index of systolic function, was higher in non-failing mid-myocardial samples (0.59±0.06μWmg(-1)) than in samples from the sub-epicardium (p=0.021) and the sub-endocardium (p=0.015). Non-failing mid-myocardial samples also produced more isometric force (14.3±1.33kNm(-2)) than samples from the sub-epicardium (p=0.008) and the sub-endocardium (p=0.026). Heart failure reduced power (p=0.009) and force (p=0.042) but affected the mid-myocardium more than the other transmural regions. Fibrosis increased with heart failure (p=0.021) and mid-myocardial tissue from failing hearts contained more collagen than matched sub-epicardial (p<0.001) and sub-endocardial (p=0.043) samples. Power output was correlated with the relative content of actin and troponin I, and was also statistically linked to the relative content and phosphorylation of desmin and myosin light chain-1. Non-failing human hearts exhibit transmural heterogeneity of contractile properties. In failing organs, region-specific fibrosis produces the greatest contractile deficits in the mid-myocardium. Targeting fibrosis and sarcomeric proteins in the mid-myocardium may be particularly effective therapies for heart failure. Copyright © 2014 Elsevier Ltd. All rights reserved.

In Silico QT and APD Prolongation Assay for Early Screening of Drug-Induced Proarrhythmic Risk.

PubMed

Romero, Lucia; Cano, Jordi; Gomis-Tena, Julio; Trenor, Beatriz; Sanz, Ferran; Pastor, Manuel; Saiz, Javier

2018-04-23

Drug-induced proarrhythmicity is a major concern for regulators and pharmaceutical companies. For novel drug candidates, the standard assessment involves the evaluation of the potassium hERG channels block and the in vivo prolongation of the QT interval. However, this method is known to be too restrictive and to stop the development of potentially valuable therapeutic drugs. The aim of this work is to create an in silico tool for early detection of drug-induced proarrhythmic risk. The system is based on simulations of how different compounds affect the action potential duration (APD) of isolated endocardial, midmyocardial, and epicardial cells as well as the QT prolongation in a virtual tissue. Multiple channel-drug interactions and state-of-the-art human ventricular action potential models ( O'Hara , T. , PLos Comput. Biol. 2011 , 7 , e1002061 ) were used in our simulations. Specifically, 206.766 cellular and 7072 tissue simulations were performed by blocking the slow and the fast components of the delayed rectifier current ( I Ks and I Kr , respectively) and the L-type calcium current ( I CaL ) at different levels. The performance of our system was validated by classifying the proarrhythmic risk of 84 compounds, 40 of which present torsadogenic properties. On the basis of these results, we propose the use of a new index (Tx) for discriminating torsadogenic compounds, defined as the ratio of the drug concentrations producing 10% prolongation of the cellular endocardial, midmyocardial, and epicardial APDs and the QT interval, over the maximum effective free therapeutic plasma concentration (EFTPC). Our results show that the Tx index outperforms standard methods for early identification of torsadogenic compounds. Indeed, for the analyzed compounds, the Tx tests accuracy was in the range of 87-88% compared with a 73% accuracy of the hERG IC 50 based test.

Left Ventricular Strain in Chemotherapy-Naive and Radiotherapy-Naive Patients With Cancer.

PubMed

Tadic, Marijana; Genger, Martin; Baudisch, Ana; Kelle, Sebastian; Cuspidi, Cesare; Belyavskiy, Evgeny; Burkhardt, Franziska; Venneri, Lucia; Attanasio, Philipp; Pieske, Burkert

2018-03-01

We sought to investigate left ventricular (LV) function and mechanics in patients with cancer before they received chemotherapy or radiotherapy, as well as the relationship between cancer and reduced LV multidirectional strain in the whole study population. The retrospective study involved 122 chemotherapy- and radiotherapy-naive patients with cancer and 45 age- and sex-matched controls with a cardiovascular risk profile similar to that of the patients with cancer. All the patients underwent echocardiographic examination before introduction of chemotherapy or radiotherapy. LV longitudinal (-19.1% ± 2.1% vs -17.8% ± 3.5%; P = 0.022), circumferential (-22.9% ± 3.5% vs -20.1% ± 4.1%; P < 0.001), and radial (40.5% ± 8.8% vs 35.2% ± 10.7%; P = 0.004) strain was significantly lower in the patients with cancer than in the control group. Endocardial and midmyocardial longitudinal LV strain was significantly reduced in the patients with cancer compared with the controls, whereas epicardial longitudinal strain was similar between these groups. Endocardial, midmyocardial, and epicardial circumferential strain was significantly lower in the chemotherapy- or radiotherapy-naive patients with cancer than in the controls. Cancer was associated with reduced longitudinal (odds ratio [OR], 9.0; 95% confidence interval [CI], 2.20-23.50; P < 0.001), reduced circumferential (OR, 7.1; 95% CI, 3.80-20.40; P < 0.001), and reduced radial strain (OR, 7.2; 95% CI, 3.41-25.10; P < 0.001) independent of age, sex, body mass index, diabetes, and hypertension. LV mechanics was impaired in the patients with cancer compared with the controls even before initiation of chemotherapy and radiotherapy. Cancer and hypertension were associated with reduced LV multidirectional strain independent of other clinical parameters. The present results indicate that cancer itself potentially induces cardiac remodelling independent of chemotherapy and radiotherapy. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Zero-fluoroscopy cryothermal ablation of atrioventricular nodal re-entry tachycardia guided by endovascular and endocardial catheter visualization using intracardiac echocardiography (Ice&ICE Trial).

PubMed

Luani, Blerim; Zrenner, Bernhard; Basho, Maksim; Genz, Conrad; Rauwolf, Thomas; Tanev, Ivan; Schmeisser, Alexander; Braun-Dullaeus, Rüdiger C

2018-01-01

Stochastic damage of the ionizing radiation to both patients and medical staff is a drawback of fluoroscopic guidance during catheter ablation of cardiac arrhythmias. Therefore, emerging zero-fluoroscopy catheter-guidance techniques are of great interest. We investigated, in a prospective pilot study, the feasibility and safety of the cryothermal (CA) slow-pathway ablation in patients with symptomatic atrioventricular-nodal-re-entry-tachycardia (AVNRT) using solely intracardiac echocardiography (ICE) for endovascular and endocardial catheter visualization. Twenty-five consecutive patients (mean age 55.6 ± 12.0 years, 17 female) with ECG-documentation or symptoms suggesting AVNRT underwent an electrophysiology study (EPS) in our laboratory utilizing ICE for catheter navigation. Supraventricular tachycardia was inducible in 23 (92%) patients; AVNRT was confirmed by appropriate stimulation maneuvers in 20 (80%) patients. All EPS in the AVNRT subgroup could be accomplished without need for fluoroscopy, relying solely on ICE-guidance. CA guided by anatomical location and slow-pathway potentials was successful in all patients, median cryo-mappings = 6 (IQR:3-10), median cryo-ablations = 2 (IQR:1-3). Fluoroscopy was used to facilitate the trans-septal puncture and localization of the ablation substrate in the remaining 3 patients (one focal atrial tachycardia and two atrioventricular-re-entry-tachycardias). Mean EPS duration in the AVNRT subgroup was 99.8 ± 39.6 minutes, ICE guided catheter placement 11.9 ± 5.8 minutes, time needed for diagnostic evaluation 27.1 ± 10.8 minutes, and cryo-application duration 26.3 ± 30.8 minutes. ICE-guided zero-fluoroscopy CA in AVNRT patients is feasible and safe. Real-time visualization of the true endovascular borders and cardiac structures allow for safe catheter navigation during the ICE-guided EPS and might be an alternative to visualization technologies using geometry reconstructions. © 2017 Wiley Periodicals, Inc.

Influence of contact force on voltage mapping: A combined magnetic resonance imaging and electroanatomic mapping study in patients with tetralogy of Fallot.

PubMed

Teijeira-Fernandez, Elvis; Cochet, Hubert; Bourier, Felix; Takigawa, Masateru; Cheniti, Ghassen; Thompson, Nathaniel; Frontera, Antonio; Camaioni, Claudia; Massouille, Gregoire; Jalal, Zakaria; Derval, Nicolas; Iriart, Xavier; Denis, Arnaud; Hocini, Meleze; Haissaguerre, Michel; Jais, Pierre; Thambo, Jean-Benoit; Sacher, Frederic

2018-03-20

Voltage criteria for ventricular mapping have been obtained from small series of patients and prioritizing high specificity. The purpose of this study was to analyse the potential influence of contact force (CF) on voltage mapping and to define voltage cutoff values for right ventricular (RV) scar using the tetralogy of Fallot as a model of transmural RV scar and magnetic resonance imaging (MRI) as reference. Fourteen patients (age 32.6 ± 14.3 years; 5 female) with repaired tetralogy of Fallot underwent high-resolution cardiac MRI (1.25 × 1.25 × 2.5 mm). Scar, defined as pixels with intensity >50% maximum, was mapped over the RV geometry and merged within the CARTO system to RV endocardial voltage maps acquired using a 3.5-mm ablation catheter with CF technology (SmartTouch, Biosense Webster). In total, 2446 points were analyzed, 915 within scars and 1531 in healthy tissue according to MRI. CF correlated to unipolar (ρ = 0.186; P <.001) and bipolar voltage in healthy tissue (ρ = 0.245; P <.001) and in scar tissue. Receiver operating characteristic curve analysis excluding points with very low CF (<5g) identified optimal voltage cutoffs of 5.19 mV for unipolar voltage and 1.76 mV for bipolar voltage, yielding sensitivity/specificity of 0.89/0.85 and 0.9/0.9, respectively. CF is an important factor to be taken into account for voltage mapping. If good CF is applied, unipolar and bipolar voltage cutoffs of 5.19 mV and 1.76 mV are optimal for identifying RV scar on endocardial mapping with the SmartTouch catheter. Data on the diagnostic accuracy of different voltage cutoff values are provided. Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Echocardiographic Image Quality Deteriorates with Age in Children and Young Adults with Duchenne Muscular Dystrophy.

PubMed

Power, Alyssa; Poonja, Sabrina; Disler, Dal; Myers, Kimberley; Patton, David J; Mah, Jean K; Fine, Nowell M; Greenway, Steven C

2017-01-01

Advances in medical care for patients with Duchenne muscular dystrophy (DMD) have resulted in improved survival and an increased prevalence of cardiomyopathy. Serial echocardiographic surveillance is recommended to detect early cardiac dysfunction and initiate medical therapy. Clinical anecdote suggests that echocardiographic quality diminishes over time, impeding accurate assessment of left ventricular systolic function. Furthermore, evidence-based guidelines for the use of cardiac imaging in DMD, including cardiac magnetic resonance imaging (CMR), are limited. The objective of our single-center, retrospective study was to quantify the deterioration in echocardiographic image quality with increasing patient age and identify an age at which CMR should be considered. We retrospectively reviewed and graded the image quality of serial echocardiograms obtained in young patients with DMD. The quality of 16 left ventricular segments in two echocardiographic views was visually graded using a binary scoring system. An endocardial border delineation percentage (EBDP) score was calculated by dividing the number of segments with adequate endocardial delineation in each imaging window by the total number of segments present in that window and multiplying by 100. Linear regression analysis was performed to model the relationship between the EBDP scores and patient age. Fifty-five echocardiograms from 13 patients (mean age 11.6 years, range 3.6-19.9) were systematically reviewed. By 13 years of age, 50% of the echocardiograms were classified as suboptimal with ≥30% of segments inadequately visualized, and by 15 years of age, 78% of studies were suboptimal. Linear regression analysis revealed a negative correlation between patient age and EBDP score ( r  = -2.49, 95% confidence intervals -4.73, -0.25; p  = 0.032), with the score decreasing by 2.5% for each 1 year increase in age. Echocardiographic image quality declines with increasing age in DMD. Alternate imaging modalities may play a role in cases of poor echocardiographic image quality.

Myocardialization of the cardiac outflow tract

NASA Technical Reports Server (NTRS)

van den Hoff, M. J.; Moorman, A. F.; Ruijter, J. M.; Lamers, W. H.; Bennington, R. W.; Markwald, R. R.; Wessels, A.

1999-01-01

During development, the single-circuited cardiac tube transforms into a double-circuited four-chambered heart by a complex process of remodeling, differential growth, and septation. In this process the endocardial cushion tissues of the atrioventricular junction and outflow tract (OFT) play a crucial role as they contribute to the mesenchymal components of the developing septa and valves in the developing heart. After fusion, the endocardial ridges in the proximal portion of the OFT initially form a mesenchymal outlet septum. In the adult heart, however, this outlet septum is basically a muscular structure. Hence, the mesenchyme of the proximal outlet septum has to be replaced by cardiomyocytes. We have dubbed this process "myocardialization." Our immunohistochemical analysis of staged chicken hearts demonstrates that myocardialization takes place by ingrowth of existing myocardium into the mesenchymal outlet septum. Compared to other events in cardiac septation, it is a relatively late process, being initialized around stage H/H28 and being basically completed around stage H/H38. To unravel the molecular mechanisms that are responsible for the induction and regulation of myocardialization, an in vitro culture system in which myocardialization could be mimicked and manipulated was developed. Using this in vitro myocardialization assay it was observed that under the standard culture conditions (i) whole OFT explants from stage H/H20 and younger did not spontaneously myocardialize the collagen matrix, (ii) explants from stage H/H21 and older spontaneously formed extensive myocardial networks, (iii) the myocardium of the OFT could be induced to myocardialize and was therefore "myocardialization-competent" at all stages tested (H/H16-30), (iv) myocardialization was induced by factors produced by, most likely, the nonmyocardial component of the outflow tract, (v) at none of the embryonic stages analyzed was ventricular myocardium myocardialization-competent, and finally, (vi) ventricular myocardium did not produce factors capable of supporting myocardialization. Copyright 1999 Academic Press.

Randomized Clinical Trials of Gene Transfer for Heart Failure with Reduced Ejection Fraction.

PubMed

Penny, William F; Hammond, H Kirk

2017-05-01

Despite improvements in drug and device therapy for heart failure, hospitalization rates and mortality have changed little in the past decade. Randomized clinical trials using gene transfer to improve function of the failing heart are the focus of this review. Four randomized clinical trials of gene transfer in heart failure with reduced ejection fraction (HFrEF) have been published. Each enrolled patients with stable symptomatic HFrEF and used either intracoronary delivery of a virus vector or endocardial injection of a plasmid. The initial CUPID trial randomized 14 subjects to placebo and 25 subjects to escalating doses of adeno-associated virus type 1 encoding sarcoplasmic reticulum calcium ATPase (AAV1.SERCA2a). AAV1.SERCA2a was well tolerated, and the high-dose group met a 6 month composite endpoint. In the subsequent CUPID-2 study, 243 subjects received either placebo or the high dose of AAV1.SERCA2a. AAV1.SERCA2a administration, while safe, failed to meet the primary or any secondary endpoints. STOP-HF used plasmid endocardial injection of stromal cell-derived factor-1 to promote stem-cell recruitment. In a 93-subject trial of patients with ischemic etiology heart failure, the primary endpoint (symptoms and 6 min walk distance) failed, but subgroup analyses showed improvements in subjects with the lowest ejection fractions. A fourth trial randomized 14 subjects to placebo and 42 subjects to escalating doses of adenovirus-5 encoding adenylyl cyclase 6 (Ad5.hAC6). There were no safety concerns, and patients in the two highest dose groups (combined) showed improvements in left ventricular function (left ventricular ejection fraction and -dP/dt). The safety data from four randomized clinical trials of gene transfer in patients with symptomatic HFrEF suggest that this approach can be conducted with acceptable risk, despite invasive delivery techniques in a high-risk population. Additional trials are necessary before the approach can be endorsed for clinical practice.

Effect of beam hardening on transmural myocardial perfusion quantification in myocardial CT imaging

NASA Astrophysics Data System (ADS)

Fahmi, Rachid; Eck, Brendan L.; Levi, Jacob; Fares, Anas; Wu, Hao; Vembar, Mani; Dhanantwari, Amar; Bezerra, Hiram G.; Wilson, David L.

2016-03-01

The detection of subendocardial ischemia exhibiting an abnormal transmural perfusion gradient (TPG) may help identify ischemic conditions due to micro-vascular dysfunction. We evaluated the effect of beam hardening (BH) artifacts on TPG quantification using myocardial CT perfusion (CTP). We used a prototype spectral detector CT scanner (Philips Healthcare) to acquire dynamic myocardial CTP scans in a porcine ischemia model with partial occlusion of the left anterior descending (LAD) coronary artery guided by pressure wire-derived fractional flow reserve (FFR) measurements. Conventional 120 kVp and 70 keV projection-based mono-energetic images were reconstructed from the same projection data and used to compute myocardial blood flow (MBF) using the Johnson-Wilson model. Under moderate LAD occlusion (FFR~0.7), we used three 5 mm short axis slices and divided the myocardium into three LAD segments and three remote segments. For each slice and each segment, we characterized TPG as the mean "endo-to-epi" transmural flow ratio (TFR). BH-induced hypoenhancement on the ischemic anterior wall at 120 kVp resulted in significantly lower mean TFR value as compared to the 70 keV TFR value (0.29+/-0.01 vs. 0.55+/-0.01 p<1e-05). No significant difference was measured between 120 kVp and 70 keV mean TFR values on segments moderately affected or unaffected by BH. In the entire ischemic LAD territory, 120 kVp mean endocardial flow was significantly reduced as compared to mean epicardial flow (15.80+/-10.98 vs. 40.85+/-23.44 ml/min/100g; p<1e-04). At 70 keV, BH was effectively minimized resulting in mean endocardial MBF of 40.85+/-15.3407 ml/min/100g vs. 74.09+/-5.07 ml/min/100g (p=0.0054) in the epicardium. We also found that BH artifact in the conventional 120 kVp images resulted in falsely reduced MBF measurements even under non-ischemic conditions.

Regional effects of streptozotocin-induced diabetes on shortening and calcium transport in epicardial and endocardial myocytes from rat left ventricle.

PubMed

Smail, Manal M A; Qureshi, Muhammad A; Shmygol, Anatoliy; Oz, Murat; Singh, Jaipaul; Sydorenko, Vadym; Arabi, Alya; Howarth, Frank C; Al Kury, Lina

2016-11-01

In the heart, the left ventricle pumps blood at higher pressure than the right ventricle. Within the left ventricle, the electromechanical properties of ventricular cardiac myocytes vary transmurally and this may be related to the gradients of stress and strain experienced in vivo across the ventricular wall. Diabetes is also associated with alterations in hemodynamic function. The aim of this study was to investigate shortening and Ca 2+ transport in epicardial (EPI) and endocardial (ENDO) left ventricular myocytes in the streptozotocin (STZ)-induced diabetic rat. Shortening, intracellular Ca 2+ and L-type Ca 2+ current (I Ca,L ) were measured by video detection, fura-2 microfluorimetry, and whole-cell patch clamp techniques, respectively. Time to peak (TPK) shortening was prolonged to similar extents in ENDO and EPI myocytes from STZ-treated rats compared to ENDO and EPI myocytes from controls. Time to half (THALF) relaxation of shortening was prolonged in ENDO myocytes from STZ-treated rats compared to ENDO controls. TPK Ca 2+ transient was prolonged in ENDO myocytes from STZ-treated rats compared to ENDO controls. THALF decay of the Ca 2+ transient was prolonged in ENDO myocytes from STZ-treated rats compared to ENDO controls. Sarcoplasmic reticulum (SR) fractional release of Ca 2+ was reduced in EPI myocytes from STZ-treated rats compared to EPI controls. I C a,L activation, inactivation, and recovery from inactivation were not significantly altered in EPI and ENDO myocytes from STZ-treated rats or controls. Regional differences in Ca 2+ transport may partly underlie differences in ventricular myocyte shortening across the wall of the healthy and the STZ-treated rat left ventricle. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Quantification of Left Ventricular Linear, Areal and Volumetric Dimensions: A Phantom and in Vivo Comparison of 2-D and Real-Time 3-D Echocardiography with Cardiovascular Magnetic Resonance.

PubMed

Polte, Christian L; Lagerstrand, Kerstin M; Gao, Sinsia A; Lamm, Carl R; Bech-Hanssen, Odd

2015-07-01

Two-dimensional echocardiography and real-time 3-D echocardiography have been reported to underestimate human left ventricular volumes significantly compared with cardiovascular magnetic resonance. We investigated the ability of 2-D echocardiography, real-time 3-D echocardiography and cardiovascular magnetic resonance to delineate dimensions of increasing complexity (diameter-area-volume) in a multimodality phantom model and in vivo, with the aim of elucidating the main cause of underestimation. All modalities were able to delineate phantom dimensions with high precision. In vivo, 2-D and real-time 3-D echocardiography underestimated short-axis end-diastolic linear and areal and all left ventricular volumetric dimensions significantly compared with cardiovascular magnetic resonance, but not short-axis end-systolic linear and areal dimensions. Underestimation increased successively from linear to volumetric left ventricular dimensions. When analyzed according to the same principles, 2-D and real-time 3-DE echocardiography provided similar left ventricular volumes. In conclusion, echocardiographic underestimation of left ventricular dimensions is due mainly to inherent technical differences in the ability to differentiate trabeculated from compact myocardium. Identical endocardial border definition criteria are needed to minimize differences between the modalities and to ensure better comparability in clinical practice. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

New concept of the contraction-extension property of the left ventricular myocardium.

PubMed

Tanaka, Motonao; Sakamoto, Tsuguya; Sugawara, Shigeo; Katahira, Yoshiaki; Tabuchi, Haruna; Nakajima, Hiroyuki; Kurokawa, Takafumi; Kanai, Hiroshi; Hasegawa, Hideyuki; Ohtsuki, Shigeo

2014-04-01

Using newly developed ultrasonic technology, we attempted to disclose the characteristics of the left ventricular (LV) contraction-extension (C-E) property, which has an important relationship to LV function. Strain rate (SR) distribution within the posterior wall and interventricular septum was microscopically measured with a high accuracy of 821μm in spatial resolution by using the phase difference tracking method. The subjects were 10 healthy men (aged 30-50 years). The time course of the SR distribution disclosed the characteristic C-E property, i.e. the contraction started from the apex and propagated toward the base on one hand, and from the epicardial side toward the endocardial side on the other hand. Therefore, the contraction of one area and the extension of another area simultaneously appeared through nearly the whole cardiac cycle, with the contracting part positively extending the latter part and vice versa. The time course of these propagations gave rise to the peristalsis and the bellows action of the LV wall, and both contributed to effective LV function. The LV contraction started coinciding in time with the P wave of the electrocardiogram, and the cardiac cycle was composed of 4 phases, including 2 types of transitional phase, as well as the ejection phase and slow filling phase. The sum of the measurement time duration of either the contraction or the extension process occupied nearly equal duration in normal conditions. The newly developed ultrasonic technology revealed that the SR distribution was important in evaluating the C-E property of the LV myocardium. The harmonious succession of the 4 cardiac phases newly identified seemed to be helpful in understanding the mechanism to keep long-lasting pump function of the LV. Copyright © 2013 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

[Technical options of electrotherapy in patients with vasovagal syncope].

PubMed

Bałczewska, Daria; Kaczmarek, Krzysztof; Ptaszyński, Paweł; Wranicz, Jerzy Krzysztof; Cygankiewicz, Iwona

2016-10-19

Syncope is a symptom of the disease with diverse etiology and can be evidence of both benign and very serious life-threatening conditions. Vasovagal syncope(VVS), with prevalence about 35% of the general population, is most frequent causes of transient loss of consciousness (T-LOC). Most cases of vasovagal syncope requires conservative treatment. Although cardioinhibitory type of VVS characterized by a significant bradycardia or pause of the heart rate and can be treated with continuous electrotherapy. This article discuss cardiac pacing and technical solutions for the treatment of VVS. Available cardiac pacing methods used to detect and break VVS such as Rate Drop Response (RDR), Closed Loop Stimulation (CLS) and rate response driven by variations of myocardial contractility like Peak Endocardial Acceleration (PEA), has been presented.

Loeffler Endocarditis: A Unique Presentation of Right-Sided Heart Failure Due to Eosinophil-Induced Endomyocardial Fibrosis.

PubMed

Alam, Amit; Thampi, Shankar; Saba, Shahryar G; Jermyn, Rita

2017-01-01

Loeffler endocarditis is a rare restrictive cardiomyopathy caused by abnormal endomyocardial infiltration of eosinophils, with subsequent tissue damage from degranulation, eventually leading to fibrosis. Although an uncommon entity, it is still a disease with significant morbidity and mortality. Often identified only at late stages, treatment options are limited once fibrosis occurs, usually requiring heart failure medications or surgical intervention. We present a unique case of a woman with remote history of hypereosinophilic syndrome, attributed to treatment of rheumatoid arthritis with infliximab, who presented with symptoms of heart failure refractory to medical management and was found to have Loeffler endocarditis. The severe progression of the disease required surgical intervention with endocardial stripping to treat the right-sided diastolic heart failure.

Lasers in the treatment of ischemic heart disease in China

NASA Astrophysics Data System (ADS)

Zhang, Yongzhen; Chen, Mingzhe

2000-10-01

Myocardial revascularization by laser is a new treatment modality for chronic, severe, refractory angina in the patients with coronary heart disease that is not amenable to angioplasty (PTCA) or bypass surgery (CABG). Transmyocardial revascularization (TMR), typically requiring open thoracotomy, uses laser to create channels that would directly carry blood from left ventricular cavity into the ischemic myocardium. Current data indicate that TMR may provide these patients with improvement in angina severity, quality of life, and myocardial perfusion. The greatest potential future use of TMR is as an adjunct to CABG in patients with disease that prevents bypass grafting due to lack of distal targets or a conduit. Recently, as percutaneous (catheter-based) myocardial revascularization (PMR) has been developed with laser technology that permits the creation of channels from the endocardial surface of the left ventricle. The early results with PMR seem encouraging. Randomized clinical trial has demonstrated symptomatic improvement and increased exercise capacity. The risk: benefit ratio for PMR appears to be much more favorable than that for TMR. The mechanisms of action of them have not yet been clearly elucidated, and several theories have been proposed, including channel patency, angiogenesis, denervation, and placebo effect. The challenge of TMR/PMR is related to improvement of perioperative outcomes and long-term survival without worsening of left ventricular function. In future, it may be feasible to combine TMR/PMR with intramyocardial delivery of angiogenic growth factors to induce further new blood vessel formation.

Echocardiographic evaluation of global left ventricular function during high thoracic epidural anesthesia.

PubMed

Niimi, Y; Ichinose, F; Saegusa, H; Nakata, Y; Morita, S

1997-03-01

To assess the effects of high thoracic epidural anesthesia on left ventricular (LV) diastolic filling and systolic function in patients without heart disease. Prospective study. University hospital. 24 ASA physical status I and II patients scheduled for elective noncardiac surgery. Patients received high thoracic (HTE; n = 12) or low thoracic (LTE; n = 12) epidural anesthesia. Left ventricular diastolic filling was noninvasively determined by precordial echocardiography using a pulsed Doppler technique and with a newly developed acoustic quantification (AQ) method that automatically detects endocardial borders and measures cavity area. All measurements were performed in awake premedicated patients. In the HTE group, the extent of sensory blockade of T1-T5, at the least, was induced with 2% lidocaine 5 ml. During HTE, systolic blood pressure (119 +/- 16 vs. 108 +/- 14 mmHg, p < 0.01), heart rate (73 +/- 9.8 vs. 63 +/- 6.8 beats/min, p < 0.01), cardiac output (CO; 4.5 +/- 1.1 vs. 3.8 +/- 1.2 L/min, p < 0.05), and fractional area change (50 +/- 11 vs. 37 +/- 11%, p < 0.01) decreased significantly, whereas end diastolic area (9.4 +/- 1.4 vs. 10.3 +/- 1.1 cm2, p < 0.01) and end systolic area (4.8 +/- 1.3 vs. 6.0 +/- 1.1 cm2, p < 0.05) showed a significant increase. As a result, stroke volume was kept constant (63 +/- 14 vs. 60 +/- 19 ml). Pulsed Doppler derived indices such as peak velocity during the early filling (E) and the atrial contraction (A) phases, peak early to atrial velocity ratio (E/A), and acceleration time remained unchanged. AQ derived peak dA/dt during the early diastolic (D1) and the atrial contraction phases (D2) and D1/D2 also remained unchanged. In contrast, in the LTE group, no significant differences were noted in all systolic and diastolic indices obtained by pulsed Doppler and AQ method. High thoracic epidural anesthesia causes a decrease in CO without changing LV ejection and diastolic filling performance in healthy subjects.

Progressive impairment of regional myocardial perfusion after initial restoration of postischemic blood flow.

PubMed

Ambrosio, G; Weisman, H F; Mannisi, J A; Becker, L C

1989-12-01

The "no-reflow" phenomenon, the occurrence of areas with very low flow in hearts reperfused after ischemia, is thought to be largely established at the time of reperfusion as a result of microvascular damage induced by ischemia. In the present study we sought to determine whether additional impairment of tissue perfusion might also occur during the course of reperfusion. Open-chest dogs were subjected to 90 minutes of left circumflex coronary artery occlusion and reperfused for 2 minutes (n = 7) or 3.5 hours (n = 8). Myocardial perfusion was visualized in left ventricular slices following in vivo injection of the fluorescent dye thioflavin-S just before killing. The area of impaired perfusion (absent thioflavin) averaged 9.5 +/- 3.0% of the risk region in dogs reperfused for 2 minutes, whereas it was nearly three times as large in dogs reperfused for 3.5 hours (25.9 +/- 8.2% of the risk region, p less than 0.05). Serial measurements of flow by microspheres during reperfusion demonstrated zones within the postischemic myocardium that were hyperemic 2 minutes after reperfusion, with adequate flow still present at 30 minutes, but with a subsequent marked fall in perfusion. After 3.5 hours these areas showed negligible flow (0.13 +/- 0.3 ml/min/g) and no thioflavin uptake. Tissue samples showing postischemic impairment in perfusion has received virtually no collateral flow during ischemia (less than 0.01 ml/min/g), whereas collateral flow was significantly higher in adjacent thioflavin-positive zones (0.04 +/- 0.01 ml/min/g in endocardial samples and 0.07 +/- 0.02 ml/min/g in samples from the midmyocardium, p less than 0.001 vs. thioflavin-negative areas). Areas that showed late impairment of flow invariably demonstrated contraction band necrosis, which contrasted with the pattern of coagulation necrosis observed in areas of "true" (i.e., immediate) no-reflow. Intracapillary erythrocyte stasis and marked intravascular neutrophil accumulation (to levels greater than 20-fold that found after 2 minutes reperfusion) were typically observed in areas of delayed impairment to flow. Obstruction to flow at the capillary level was confirmed in additional dogs in which the heart was injected postmortem with silicone rubber to delineate the microvascular filling pattern. Areas of absent capillary filling were much more extensive after 3.5 hours than after 2 minutes reperfusion. Thus, this study shows that the occurrence of areas of markedly impaired perfusion in postischemic myocardium is related only in part to an inability to reperfuse certain areas on reflow. A more important factor is represented by a delayed, progressive fall in flow to areas that initially received adequate reperfusion.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of nitroglycerin during cardiopulmonary resuscitation.

PubMed

Stefaniotou, Antonia; Varvarousi, Giolanda; Varvarousis, Dimitrios P; Xanthos, Theodoros

2014-07-05

The outcome for both in-hospital and out-of hospital cardiac arrest remains dismal. Vasopressors are used to increase coronary perfusion pressure and thus facilitate return of spontaneous circulation during cardiopulmonary resuscitation. However, they are associated with a number of potential adverse effects and may decrease endocardial and cerebral organ blood flow. Nitroglycerin has a favourable haemodynamic profile which promotes forward blood flow. Several studies suggest that combined use of nitroglycerin with vasopressors during resuscitation, is associated with increased rates of resuscitation and improved post-resuscitation outcome. This article reviews the effects of nitroglycerin during cardiopulmonary resuscitation and postresuscitation period, as well as the beneficial outcomes of a combination regimen consisting of a vasopressor and a vasodilator, such as nitroglycerin. Copyright © 2014 Elsevier B.V. All rights reserved.

The new era of cardiac surgery: hybrid therapy for cardiovascular disease.

PubMed

Solenkova, Natalia V; Umakanthan, Ramanan; Leacche, Marzia; Zhao, David X; Byrne, John G

2010-11-01

Surgical therapy for cardiovascular disease carries excellent long-term outcomes but it is relatively invasive. With the development of new devices and techniques, modern cardiovascular surgery is trending toward less invasive approaches, especially for patients at high risk for traditional open heart surgery. A hybrid strategy combines traditional surgical treatments performed in the operating room with treatments traditionally available only in the catheterization laboratory with the goal of offering patients the best available therapy for any set of cardiovascular diseases. Examples of hybrid procedures include hybrid coronary artery bypass grafting, hybrid valve surgery and percutaneous coronary intervention, hybrid endocardial and epicardial atrial fibrillation procedures, and hybrid coronary artery bypass grafting/carotid artery stenting. This multidisciplinary approach requires strong collaboration between cardiac surgeons, vascular surgeons, and interventional cardiologists to obtain optimal patient outcomes.

A Review of the Relevant Embryology, Pathohistology, and Anatomy of the Left Atrial Appendage for the Invasive Cardiac Electrophysiologist

PubMed Central

DeSimone, Christopher V.; Gaba, Prakriti; Tri, Jason; Syed, Faisal; Noheria, Amit; Asirvatham, Samuel J.

2016-01-01

The three-dimensional morphology of the left atrial appendage provides the substrate for thrombus generation, and is a harbinger for embolic material due to its direct connection to the left-sided circulation. Appreciating the development of the appendage from mesodermal layer to its adult form provides the basis to improve exclusion from the atrial circulation, and thereby can lead to a significant reduction in stroke risk. This process also provides insight into the role of the left atrial appendage as an endocrine organ, its involvement in fluid homeostasis, and its connection to the autonomic nervous system. Knowledge of the surrounding structural arrangement is critical to identify landmarks from both an endocardial and epicardial perspective to improve targeted device placement. Furthermore, correlation of the left atrial appendage body, neck, and ostium to the surrounding anatomy can also improve both procedural efficacy and safety. In addition, a working knowledge of the regional anatomy adds a prudent degree of awareness for procedural complications, and allows for early identification and timely intervention as these situations arise. A detailed understanding of the left atrial appendage embryology, histology, and gross anatomy is imperative to identify the correct device and approach for each individual patient. In addition, this increased awareness can identify areas that are in need of further innovation, and thus provide the ability to adapt and refine existing technologies to overcome pitfalls currently facing catheter-based approaches. PMID:27087889

"3D fusion" echocardiography improves 3D left ventricular assessment: comparison with 2D contrast echocardiography.

PubMed

Augustine, Daniel; Yaqub, Mohammad; Szmigielski, Cezary; Lima, Eduardo; Petersen, Steffen E; Becher, Harald; Noble, J Alison; Leeson, Paul

2015-02-01

Three-dimensional fusion echocardiography (3DFE) is a novel postprocessing approach that utilizes imaging data acquired from multiple 3D acquisitions. We assessed image quality, endocardial border definition, and cardiac wall motion in patients using 3DFE compared to standard 3D images (3D) and results obtained with contrast echocardiography (2DC). Twenty-four patients (mean age 66.9 ± 13 years, 17 males, 7 females) undergoing 2DC had three, noncontrast, 3D apical volumes acquired at rest. Images were fused using an automated image fusion approach. Quality of the 3DFE was compared to both 3D and 2DC based on contrast-to-noise ratio (CNR) and endocardial border definition. We then compared clinical wall-motion score index (WMSI) calculated from 3DFE and 3D to those obtained from 2DC images. Fused 3D volumes had significantly improved CNR (8.92 ± 1.35 vs. 6.59 ± 1.19, P < 0.0005) and segmental image quality (2.42 ± 0.99 vs. 1.93 ± 1.18, P < 0.005) compared to unfused 3D acquisitions. Levels achieved were closer to scores for 2D contrast images (CNR: 9.04 ± 2.21, P = 0.6; segmental image quality: 2.91 ± 0.37, P < 0.005). WMSI calculated from fused 3D volumes did not differ significantly from those obtained from 2D contrast echocardiography (1.06 ± 0.09 vs. 1.07 ± 0.15, P = 0.69), whereas unfused images produced significantly more variable results (1.19 ± 0.30). This was confirmed by a better intraclass correlation coefficient (ICC 0.72; 95% CI 0.32-0.88) relative to comparisons with unfused images (ICC 0.56; 95% CI 0.02-0.81). 3DFE significantly improves left ventricular image quality compared to unfused 3D in a patient population and allows noncontrast assessment of wall motion that approaches that achieved with 2D contrast echocardiography. © 2014, Wiley Periodicals, Inc.

Atrial fibrillation driven by micro-anatomic intramural re-entry revealed by simultaneous sub-epicardial and sub-endocardial optical mapping in explanted human hearts.

PubMed

Hansen, Brian J; Zhao, Jichao; Csepe, Thomas A; Moore, Brandon T; Li, Ning; Jayne, Laura A; Kalyanasundaram, Anuradha; Lim, Praise; Bratasz, Anna; Powell, Kimerly A; Simonetti, Orlando P; Higgins, Robert S D; Kilic, Ahmet; Mohler, Peter J; Janssen, Paul M L; Weiss, Raul; Hummel, John D; Fedorov, Vadim V

2015-09-14

The complex architecture of the human atria may create physical substrates for sustained re-entry to drive atrial fibrillation (AF). The existence of sustained, anatomically defined AF drivers in humans has been challenged partly due to the lack of simultaneous endocardial-epicardial (Endo-Epi) mapping coupled with high-resolution 3D structural imaging. Coronary-perfused human right atria from explanted diseased hearts (n = 8, 43-72 years old) were optically mapped simultaneously by three high-resolution CMOS cameras (two aligned Endo-Epi views (330 µm2 resolution) and one panoramic view). 3D gadolinium-enhanced magnetic resonance imaging (GE-MRI, 80 µm3 resolution) revealed the atrial wall structure varied in thickness (1.0 ± 0.7-6.8 ± 2.4 mm), transmural fiber angle differences, and interstitial fibrosis causing transmural activation delay from 23 ± 11 to 43 ± 22 ms at increased pacing rates. Sustained AF (>90 min) was induced by burst pacing during pinacidil (30-100 µM) perfusion. Dual-sided sub-Endo-sub-Epi optical mapping revealed that AF was driven by spatially and temporally stable intramural re-entry with 107 ± 50 ms cycle length and transmural activation delay of 67 ± 31 ms. Intramural re-entrant drivers were captured primarily by sub-Endo mapping, while sub-Epi mapping visualized re-entry or 'breakthrough' patterns. Re-entrant drivers were anchored on 3D micro-anatomic tracks (15.4 ± 2.2 × 6.0 ± 2.3 mm2, 2.9 ± 0.9 mm depth) formed by atrial musculature characterized by increased transmural fiber angle differences and interstitial fibrosis. Targeted radiofrequency ablation of the tracks verified these re-entries as drivers of AF. Integrated 3D structural-functional mapping of diseased human right atria ex vivo revealed that the complex atrial microstructure caused significant differences between Endo vs. Epi activation during pacing and sustained AF driven by intramural re-entry anchored to fibrosis-insulated atrial bundles. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Gene expression of stretch-activated channels and mechanoelectric feedback in the heart.

PubMed

Kelly, D; Mackenzie, L; Hunter, P; Smaill, B; Saint, D A

2006-07-01

1. Mechanoelectric feedback (MEF) in the heart is the process by which mechanical forces on the myocardium can change its electrical properties. Mechanoelectric feedback has been demonstrated in many animal models, ranging from isolated cells, through isolated hearts to whole animals. In humans, MEF has been demonstrated directly in both the atria and the ventricles. It seems likely that MEF provides either the trigger or the substrate for some types of clinically important arrhythmias. 2. Mechanoelectric feedback may arise because of the presence of stretch-sensitive (or mechano-sensitive) ion channels in the cell membrane of the cardiac myocytes. Two types have been demonstrated: (i) a non-specific cation channel (stretch-activated channel (SAC); conductance of approximately 25 pS); and (ii) a potassium channel with a conductance of approximately 100 pS. The gene coding for the SAC has not yet been identified. The gene for the potassium channel is likely to be TREK, a member of the tandem pore potassium channel gene family. We have recorded stretch-sensitive potassium channels in rat isolated myocytes that have the properties of TREK channels expressed in heterologous systems. 3. It has been shown that TREK mRNA is expressed heterogeneously in the rat ventricular wall, with 17-fold more expression in endocardial compared with epicardial cells. This difference is reflected in the TREK currents recorded from endocardial and epicardial cells using whole-cell patch-clamp techniques, although the difference in current density was less pronounced (approximately threefold). Consistent with this, we show here that when the ventricle is stretched by inflation of an intraventricular balloon in a Langendorff perfused rat isolated heart, action potential shortening was more pronounced in the endocardium (30% shortening at 40 mmHg) compared with that in the epicardium (10% shortening at the same pressure). 4. Computer models of the mechanics of the (pig) heart show pronounced spatial variations in strain in the myocardium with large transmural differences (in the left ventricle in particular) and also large differences between the base and apex of the ventricle. 5. The importance of MEF and the non-homogeneous gene expression and strain distribution for arrhythmias is discussed.

Dark blood late enhancement imaging.

PubMed

Kellman, Peter; Xue, Hui; Olivieri, Laura J; Cross, Russell R; Grant, Elena K; Fontana, Marianna; Ugander, Martin; Moon, James C; Hansen, Michael S

2016-11-07

Bright blood late gadolinium enhancement (LGE) imaging typically achieves excellent contrast between infarcted and normal myocardium. However, the contrast between the myocardial infarction (MI) and the blood pool is frequently suboptimal. A large fraction of infarctions caused by coronary artery disease are sub-endocardial and thus adjacent to the blood pool. It is not infrequent that sub-endocardial MIs are difficult to detect or clearly delineate. In this present work, an inversion recovery (IR) T2 preparation was combined with single shot steady state free precession imaging and respiratory motion corrected averaging to achieve dark blood LGE images with good signal to noise ratio while maintaining the desired spatial and temporal resolution. In this manner, imaging was conducted free-breathing, which has benefits for image quality, patient comfort, and clinical workflow in both adults and children. Furthermore, by using a phase sensitive inversion recovery reconstruction the blood signal may be made darker than the myocardium (i.e., negative signal values) thereby providing contrast between the blood and both the MI and remote myocardium. In the proposed approach, a single T1-map scout was used to measure the myocardial and blood T1 using a MOdified Look-Locker Inversion recovery (MOLLI) protocol and all protocol parameters were automatically calculated from these values within the sequence thereby simplifying the user interface. The contrast to noise ratio (CNR) between MI and remote myocardium was measured in n = 30 subjects with subendocardial MI using both bright blood and dark blood protocols. The CNR for the dark blood protocol had a 13 % loss compared to the bright blood protocol. The CNR between the MI and blood pool was positive for all dark blood cases, and was negative in 63 % of the bright blood cases. The conspicuity of subendocardial fibrosis and MI was greatly improved by dark blood (DB) PSIR as well as the delineation of the subendocardial border. Free-breathing, dark blood PSIR LGE imaging was demonstrated to improve the visualization of subendocardial MI and fibrosis in cases with low contrast with adjacent blood pool. The proposed method also improves visualization of thin walled fibrous structures such as atrial walls and valves, as well as papillary muscles.

Cardiac Ventricular HIFU: Convergence of Experiment and Theory in the Canine Model

NASA Astrophysics Data System (ADS)

Muratore, Robert; Abe, Yukio; Homma, Shunichi; Bernardi, Richard; Kalisz, Andrew; Feleppa, Ernest J.

2007-05-01

OBJECTIVE: HIFU is a promising technique for treating cardiac ventricular diseases such as sustained ventricular tachycardia. Ablations can potentially destroy arrhythmogenic foci and block reentrant circuits. Towards this end, we have learned to control HIFU lesions in the canine model in vivo. METHODS: Experiment — Thoracotomies were performed on anesthetized dogs, following IACUC guidelines. In this open-chest configuration, a polyethylene water-filled bag was coupled to the myocardium with degassed ultrasound gel. The transducer was lowered into the water. Ventricular locations were targeted and insonified with multiple 200-ms HIFU bursts of 60-W acoustic power; the bursts were triggered with the electrocardiogram QRS complex. The therapeutic transducer was a 35-mm focal length, 33-mm diameter PZT annular array, excited at 5.25 MHz. Its -3dB focal region dimensions were 2.5 mm axially and 0.3 mm transversely. A confocal diagnostic transducer was used for aiming and for recording backscattered radiofrequency ultrasound data. Theory — A comprehensive acoustic model has been developed. Individual modules numerically simulate physical processes such as ultrasound beam propagation, energy transfer, and heat flow within tissue. One set of modules simulates HIFU ablation in moving tissue. Tissue motion was obtained from digitized B-mode videos of transverse cross sections of a beating canine heart. Epicardial and endocardial surface positions were extracted from the video frames. Additional simulations of static tissue compared linear and nonlinear propagation models. RESULTS: Significant agreement between simulated and measured lesion sizes and between linear and nonlinear propagation models was demonstrated.

Passive Ventricular Mechanics Modelling Using MRI of Structure and Function

PubMed Central

Wang, V.Y.; Lam, H.I.; Ennis, D.B.; Young, A.A.; Nash, M.P.

2009-01-01

Patients suffering from dilated cardiomyopathy or myocardial infarction can develop left ventricular (LV) diastolic impairment. The LV remodels its structure and function to adapt to pathophysiological changes in geometry and loading conditions and this remodeling process can alter the passive ventricular mechanics. In order to better understand passive ventricular mechanics, a LV finite element model was developed to incorporate physiological and mechanical information derived from in vivo magnetic resonance imaging (MRI) tissue tagging, in vivo LV cavity pressure recording and ex vivo diffusion tensor MRI (DTMRI) of a canine heart. MRI tissue tagging enables quantitative evaluation of cardiac mechanical function with high spatial and temporal resolution, whilst the direction of maximum water diffusion (the primary eigenvector) in each voxel of a DTMRI directly correlates with the myocardial fibre orientation. This model was customized to the geometry of the canine LV during diastasis by fitting the segmented epicardial and endocardial surface data from tagged MRI using nonlinear finite element fitting techniques. Myofibre orientations, extracted from DTMRI of the same heart, were incorporated into this geometric model using a free form deformation methodology. Pressure recordings, temporally synchronized to the tissue tagging MRI data, were used to simulate the LV deformation during diastole. Simulation of the diastolic LV mechanics allowed us to estimate the stiffness of the passive LV myocardium based on kinematic data obtained from tagged MRI. This integrated physiological model will allow more insight into the regional passive diastolic mechanics of the LV on an individualized basis, thereby improving our understanding of the underlying structural basis of mechanical dysfunction in pathological conditions. PMID:18982680

Slow adaptation of ventricular repolarization as a cause of arrhythmia?

PubMed

Bueno-Orovio, A; Hanson, B M; Gill, J S; Taggart, P; Rodriguez, B

2014-01-01

This article is part of the Focus Theme of Methods of Information in Medicine on "Biosignal Interpretation: Advanced Methods for Studying Cardiovascular and Respiratory Systems". Adaptation of the QT-interval to changes in heart rate reflects on the body-surface electrocardiogram the adaptation of action potential duration (APD) at the cellular level. The initial fast phase of APD adaptation has been shown to modulate the arrhythmia substrate. Whether the slow phase is potentially proarrhythmic remains unclear. To analyze in-vivo human data and use computer simulations to examine effects of the slow APD adaptation phase on dispersion of repolarization and reentry in the human ventricle. Electrograms were acquired from 10 left and 10 right ventricle (LV/RV) endocardial sites in 15 patients with normal ventricles during RV pacing. Activation-recovery intervals, as a surrogate for APD, were measured during a sustained increase in heart rate. Observed dynamics were studied using computer simulations of human tissue electrophysiology. Spatial heterogeneity of rate adaptation was observed in all patients. Inhomogeneity in slow APD adaptation time constants (Δτ(s)) was greater in LV than RV (Δτ(s)(LV) = 31.8 ± 13.2, Δτ(s)(RV) = 19.0 ± 12.8 s , P< 0.01). Simulations showed that altering local slow time constants of adaptation was sufficient to convert partial wavefront block to block with successful reentry. Using electrophysiological data acquired in-vivo in human and computer simulations, we identify heterogeneity in the slow phase of APD adaptation as an important component of arrhythmogenesis.

Passive ventricular mechanics modelling using MRI of structure and function.

PubMed

Wang, V Y; Lam, H I; Ennis, D B; Young, A A; Nash, M P

2008-01-01

Patients suffering from dilated cardiomyopathy or myocardial infarction can develop left ventricular (LV) diastolic impairment. The LV remodels its structure and function to adapt to pathophysiological changes in geometry and loading conditions and this remodeling process can alter the passive ventricular mechanics. In order to better understand passive ventricular mechanics, a LV finite element model was developed to incorporate physiological and mechanical information derived from in vivo magnetic resonance imaging (MRI) tissue tagging, in vivo LV cavity pressure recording and ex vivo diffusion tensor MRI (DTMRI) of a canine heart. MRI tissue tagging enables quantitative evaluation of cardiac mechanical function with high spatial and temporal resolution, whilst the direction of maximum water diffusion (the primary eigenvector) in each voxel of a DTMRI directly correlates with the myocardial fibre orientation. This model was customized to the geometry of the canine LV during diastasis by fitting the segmented epicardial and endocardial surface data from tagged MRI using nonlinear finite element fitting techniques. Myofibre orientations, extracted from DTMRI of the same heart, were incorporated into this geometric model using a free form deformation methodology. Pressure recordings, temporally synchronized to the tissue tagging MRI data, were used to simulate the LV deformation during diastole. Simulation of the diastolic LV mechanics allowed us to estimate the stiffness of the passive LV myocardium based on kinematic data obtained from tagged MRI. This integrated physiological model will allow more insight into the regional passive diastolic mechanics of the LV on an individualized basis, thereby improving our understanding of the underlying structural basis of mechanical dysfunction in pathological conditions.

Estimating the surface area of birds: using the homing pigeon (Columba livia) as a model.

PubMed

Perez, Cristina R; Moye, John K; Pritsos, Chris A

2014-05-08

Estimation of the surface area of the avian body is valuable for thermoregulation and metabolism studies as well as for assessing exposure to oil and other surface-active organic pollutants from a spill. The use of frozen carcasses for surface area estimations prevents the ability to modify the posture of the bird. The surface area of six live homing pigeons in the fully extended flight position was estimated using a noninvasive method. An equation was derived to estimate the total surface area of a pigeon based on its body weight. A pigeon's surface area in the fully extended flight position is approximately 4 times larger than the surface area of a pigeon in the perching position. The surface area of a bird is dependent on its physical position, and, therefore, the fully extended flight position exhibits the maximum area of a bird and should be considered the true surface area of a bird. © 2014. Published by The Company of Biologists Ltd | Biology Open.

Using electrical impedance to predict catheter-endocardial contact during RF cardiac ablation.

PubMed

Cao, Hong; Tungjitkusolmun, Supan; Choy, Young Bin; Tsai, Jang-Zern; Vorperian, Vicken R; Webster, John G

2002-03-01

During radio-frequency (RF) cardiac catheter ablation, there is little information to estimate the contact between the catheter tip electrode and endocardium because only the metal electrode shows up under fluoroscopy. We present a method that utilizes the electrical impedance between the catheter electrode and the dispersive electrode to predict the catheter tip electrode insertion depth into the endocardium. Since the resistivity of blood differs from the resistivity of the endocardium, the impedance increases as the catheter tip lodges deeper in the endocardium. In vitro measurements yielded the impedance-depth relations at 1, 10, 100, and 500 kHz. We predict the depth by spline curve interpolation using the obtained calibration curve. This impedance method gives reasonably accurate predicted depth. We also evaluated alternative methods, such as impedance difference and impedance ratio.

Measuring the specific surface area of natural and manmade glasses: effects of formation process, morphology, and particle size

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

Papelis, Charalambos; Um, Wooyong; Russel, Charles E.

2003-03-28

The specific surface area of natural and manmade solid materials is a key parameter controlling important interfacial processes in natural environments and engineered systems, including dissolution reactions and sorption processes at solid-fluid interfaces. To improve our ability to quantify the release of trace elements trapped in natural glasses, the release of hazardous compounds trapped in manmade glasses, or the release of radionuclides from nuclear melt glass, we measured the specific surface area of natural and manmade glasses as a function of particle size, morphology, and composition. Volcanic ash, volcanic tuff, tektites, obsidian glass, and in situ vitrified rock were analyzed.more » Specific surface area estimates were obtained using krypton as gas adsorbent and the BET model. The range of surface areas measured exceeded three orders of magnitude. A tektite sample had the highest surface area (1.65 m2/g), while one of the samples of in situ vitrified rock had the lowest surf ace area (0.0016 m2/g). The specific surface area of the samples was a function of particle size, decreasing with increasing particle size. Different types of materials, however, showed variable dependence on particle size, and could be assigned to one of three distinct groups: (1) samples with low surface area dependence on particle size and surface areas approximately two orders of magnitude higher than the surface area of smooth spheres of equivalent size. The specific surface area of these materials was attributed mostly to internal porosity and surface roughness. (2) samples that showed a trend of decreasing surface area dependence on particle size as the particle size increased. The minimum specific surface area of these materials was between 0.1 and 0.01 m2/g and was also attributed to internal porosity and surface roughness. (3) samples whose surface area showed a monotonic decrease with increasing particle size, never reaching an ultimate surface area limit within the particle size range examined. The surface area results were consistent with particle morphology, examined by scanning electron microscopy, and have significant implications for the release of radionuclides and toxic metals in the environment.« less

Effects of increased left ventricular wall thickness on the myocardium in severe aortic stenosis with normal left ventricular ejection fraction: Two- and three-dimensional multilayer speckle tracking echocardiography.

PubMed

Cho, Eun Jeong; Park, Sung-Ji; Kim, Eun Kyoung; Lee, Ga Yeon; Chang, Sung-A; Choi, Jin-Oh; Lee, Sang-Chol; Park, Seung Woo

2017-04-01

The aim of this study was to determine the capability of real time three-dimensional echocardiography (RT3DE) and two-dimensional (2D) multilayer speckle tracking echocardiography (MSTE) for evaluation of early myocardial dysfunction triggered by increased left ventricular (LV) wall thickness in severe aortic stenosis (AS) with normal LV ejection fraction (EF≥55%). Conventional, RT3D STE and 2D MSTE were performed in 45 patients (mean 68.9±9.0 years) with severe AS (aortic valve area <1 cm 2 , aortic velocity Vmax >4 m/s or mean PG >40 mm Hg) and normal left ventricular ejection fraction (LVEF) without overt coronary artery disease and in 18 age-, sex-matched healthy controls. Global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS), and global radial strain (GRS) were calculated using RT3DE and MSTE. The severe AS group had lower 3D GLS, GRS, GAS and 2D epicardium, and mid-wall and endocardium GLS compared to healthy controls. In MSTE analysis, 2D LS and CS values decreased from the endocardial layer toward the epicardial layer. Severe AS patients with increased LV wall thickness had lower 3D GLS and 2D epicardium, and mid-wall and endocardium GLS compared with severe AS patients without LV wall thickening. GLS on RT3D STE was correlated with GLS on 2D MSTE, left ventricular mass index, LVEF, left atrial volume index, and lnNT-proBNP. RT3DE and 2D MSTE can be used to identify subtle contractile dysfunction triggered by increased LV wall thickness in severe AS with normal LVEF. Therefore, RT3D STE and 2D MSTE may provide additional information that can facilitate decision-making regarding severe AS patients with increased LV wall thickness and normal LV function. © 2017, Wiley Periodicals, Inc.

Lp-dual affine surface area

NASA Astrophysics Data System (ADS)

Wei, Wang; Binwu, He

2008-12-01

According to the notion of Lp-affine surface area by Lutwak, in this paper, we introduce the concept of Lp-dual affine surface area. Further, we establish the affine isoperimetric inequality and the Blaschke-Santaló inequality for Lp-dual affine surface area. Besides, the dual Brunn-Minkowski inequality for Lp-dual affine surface area is presented.

Mercury Underpotential Deposition to Determine Iridium and Iridium Oxide Electrochemical Surface Areas

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

Alia, Shaun M.; Hurst, Katherine E.; Kocha, Shyam S.

Determining the surface areas of electrocatalysts is critical for separating the key properties of area-specific activity and electrochemical surface area from mass activity. Hydrogen underpotential deposition and carbon monoxide oxidation are typically used to evaluate iridium (Ir) surface areas, but are ineffective on oxides and can be sensitive to surface oxides formed on Ir metals. Mercury underpotential deposition is presented in this study as an alternative, able to produce reasonable surface areas on Ir and Ir oxide nanoparticles, and able to produce similar surface areas prior to and following characterization in oxygen evolution. Reliable electrochemical surface areas allow for comparativemore » studies of different catalyst types and the characterization of advanced oxygen evolution catalysts. Lastly, they also enable the study of catalyst degradation in durability testing, both areas of increasing importance within electrolysis and electrocatalysis.« less

Mercury Underpotential Deposition to Determine Iridium and Iridium Oxide Electrochemical Surface Areas

DOE PAGES

Alia, Shaun M.; Hurst, Katherine E.; Kocha, Shyam S.; ...

2016-06-02

Determining the surface areas of electrocatalysts is critical for separating the key properties of area-specific activity and electrochemical surface area from mass activity. Hydrogen underpotential deposition and carbon monoxide oxidation are typically used to evaluate iridium (Ir) surface areas, but are ineffective on oxides and can be sensitive to surface oxides formed on Ir metals. Mercury underpotential deposition is presented in this study as an alternative, able to produce reasonable surface areas on Ir and Ir oxide nanoparticles, and able to produce similar surface areas prior to and following characterization in oxygen evolution. Reliable electrochemical surface areas allow for comparativemore » studies of different catalyst types and the characterization of advanced oxygen evolution catalysts. Lastly, they also enable the study of catalyst degradation in durability testing, both areas of increasing importance within electrolysis and electrocatalysis.« less

Calculating landscape surface area from digital elevation models

Treesearch

Jeff S. Jenness

2004-01-01

There are many reasons to want to know the true surface area of the landscape, especially in landscape analysis and studies of wildlife habitat. Surface area provides a better estimate of the land area available to an animal than planimetric area, and the ratio of this surface area to planimetric area provides a useful measure of topographic roughness of the landscape...

On the influence of substrate morphology and surface area on phytofauna

USGS Publications Warehouse

Becerra-Munoz, S.; Schramm, H.L.

2007-01-01

The independent effects and interactions between substrate morphology and substrate surface area on invertebrate density or biomass colonizing artificial plant beds were assessed in a clear-water and a turbid playa lake in Castro County, Texas, USA. Total invertebrate density and biomass were consistently greater on filiform substrates than on laminar substrates with equivalent substrate surface areas. The relationship among treatments (substrates with different morphologies and surface areas) and response (invertebrate density or biomass) was assessed with equally spaced surface areas. Few statistically significant interactions between substrate morphology and surface area were detected, indicating that these factors were mostly independent from each other in their effect on colonizing invertebrates. Although infrequently, when substrate morphology and surface area were not independent, the effects of equally spaced changes in substrate surface area on the rate of change of phytofauna density or biomass per unit of substrate surface area were dependent upon substrate morphology. The absence of three-way interactions indicated that effects of substrate morphology and substrate area on phytofauna density or biomass were independent of environmental conditions outside and inside exclosures. ?? 2006 Springer Science+Business Media B.V.

Evaluation of Advanced Reactive Surface Area Estimates for Improved Prediction of Mineral Reaction Rates in Porous Media

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Mitnick, E. H.; Zhang, S.; Voltolini, M.; Yang, L.; Steefel, C. I.; Swift, A.; Cole, D. R.; Sheets, J.; Kneafsey, T. J.; Landrot, G.; Anovitz, L. M.; Mito, S.; Xue, Z.; Ajo Franklin, J. B.; DePaolo, D.

2015-12-01

CO2 sequestration in deep sedimentary formations is a promising means of reducing atmospheric CO2 emissions but the rate and extent of mineral trapping remains difficult to predict. Reactive transport models provide predictions of mineral trapping based on laboratory mineral reaction rates, which have been shown to have large discrepancies with field rates. This, in part, may be due to poor quantification of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area are ad hoc and typically based on grain size, adjusted several orders of magnitude to account for surface roughness and reactivity. This results in orders of magnitude discrepancies in estimated surface areas that directly translate into orders of magnitude discrepancies in model predictions. Additionally, natural systems can be highly heterogeneous and contain abundant nano- and micro-porosity, which can limit connected porosity and access to mineral surfaces. In this study, mineral-specific accessible surface areas are computed for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan). Accessible mineral surface areas are determined from a multi-scale image analysis including X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB. Powder and flow-through column laboratory experiments are performed and the evolution of solutes in the aqueous phase is tracked. Continuum-scale reactive transport models are used to evaluate the impact of reactive surface area on predictions of experimental reaction rates. Evaluated reactive surface areas include geometric and specific surface areas (eg. BET) in addition to their reactive-site weighted counterparts. The most accurate predictions of observed powder mineral dissolution rates were obtained through use of grain-size specific surface areas computed from a BET-based correlation. Effectively, this surface area reflects the grain-fluid contact area, or accessible surface area, in the powder dissolution experiment. In the model of the flow-through column experiment, the accessible mineral surface area, computed from the multi-scale image analysis, is evaluated in addition to the traditional surface area estimates.

Mapping the articular contact area of the long head of the biceps tendon on the humeral head.

PubMed

Morris, Brent J; Byram, Ian R; Lathrop, Ray A; Dunn, Warren R; Kuhn, John E

2014-01-01

The purpose of this investigation was to calculate the contact surface area of the long head of the biceps (LHB) in neutral position and abduction. We sought to determine whether the LHB articulates with the humeral head in a consistent pattern comparing articular contact area in neutral position and abduction. Eleven fresh frozen matched cadaveric shoulders were analyzed. The path of the biceps tendon on the articular surface of the humeral head and the total articular surface were digitized using a MicronTracker 2 H3-60 three-dimensional optical tracker. Contact surface area was significantly less in abduction than in neutral position (P = 0.002) with a median ratio of 41% (36%, 47.5%). Ratios of contact area in neutral position to full articular surface area were consistent between left and right shoulders (rho = 1, P = 0.017) as were ratios of abduction area to full articular surface area (rho = 0.97, P = 0.005). The articular contact surface area is significantly greater in neutral position than abduction. The ratios of articular contact surface areas to total humeral articular surface areas have a narrow range and are consistent between left and right shoulders of the same cadaver.

Development of unbonded and bonded areas in relation to Populus species wood characteristics in grinding

Treesearch

L.K. Lehtonen; J.H. Lehto; A.W. Rudie

2004-01-01

In terms of fibre development in mechanical pulping, most of the energy is spent on the creation of specific surface area. The total surface area created can be divided into two categories: surface area that adds to the unbonded area (optical properties) and surface area that adds to the bonded area (strength properties) of mechanical papers. This paper considers these...

Quantification of myocardial infarction: a comparison of single photon-emission computed tomography with pyrophosphate to serial plasma MB-creatine kinase measurements

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

Jansen, D.E.; Corbett, J.R.; Wolfe, C.L.

1985-08-01

Single photon-emission computed tomography (SPECT) with /sup 99m/Tc-pyrophosphate (PPi) has been shown to estimate size of myocardial infarction accurately in animals. The authors tested the hypothesis that SPECT with /sup /sup 99m//Tc-PPi and blood pool subtraction can provide prompt and accurate estimates of size of myocardial infarction in patients. SPECT estimates are potentially available early after the onset of infarction and should correlate with estimates of infarct size calculated from serial measurements of plasma MB-creatine kinase (CK) activity. Thirty-three patients with acute myocardial infarction and 16 control patients without acute myocardial infarction were studied. Eleven of the patients had transmuralmore » anterior myocardial infarction, 16 had transmural inferior myocardial infarction, and six had nontransmural myocardial infarction. SPECT was performed with a commercially available rotating gamma camera. Identical projection images of the distribution of 99mTc-PPi and the ungated cardiac blood pool were acquired sequentially over 180 degrees. Reconstructed sections were color coded and superimposed for purposes of localization of infarct. Areas of increased PPi uptake within myocardial infarcts were thresholded at 65% of peak activity. The blood pool was thresholded at 50% and subtracted to determine the endocardial border for the left ventricle. Myocardial infarcts ranged in size from 1 to 126 gram equivalents (geq) MB-CK. The correlation of MB-CK estimates of size of infarct with size determined by SPECT (both in geq) was good (r = .89 with a regression line of y = 13.1 + 1.5x).« less

Effect of solution and leaf surface polarity on droplet spread area and contact angle.

PubMed

Nairn, Justin J; Forster, W Alison; van Leeuwen, Rebecca M

2016-03-01

How much an agrochemical spray droplet spreads on a leaf surface can significantly influence efficacy. This study investigates the effect solution polarity has on droplet spreading on leaf surfaces and whether the relative leaf surface polarity, as quantified using the wetting tension dielectric (WTD) technique, influences the final spread area. Contact angles and spread areas were measured using four probe solutions on 17 species. Probe solution polarity was found to affect the measured spread area and the contact angle of the droplets on non-hairy leaves. Leaf hairs skewed the spread area measurement, preventing investigation of the influence of surface polarity on hairy leaves. WTD-measured leaf surface polarity of non-hairy leaves was found to correlate strongly with the effect of solution polarity on spread area. For non-polar leaf surfaces the spread area decreases with increasing solution polarity, for neutral surfaces polarity has no effect on spread area and for polar leaf surfaces the spread area increases with increasing solution polarity. These results attest to the use of the WTD technique as a means to quantify leaf surface polarity. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Assessment of myocardial viability: comparison of echocardiography versus cardiac magnetic resonance imaging in the current era.

PubMed

Tomlinson, David R; Becher, Harald; Selvanayagam, Joseph B

2008-06-01

Detecting viable myocardium, whether hibernating or stunned, is of clinical significance in patients with coronary artery disease and left ventricular dysfunction. Echocardiographic assessments of myocardial thickening and endocardial excursion during dobutamine infusion provide a highly specific marker for myocardial viability, but with relatively less sensitivity. The additional modalities of myocardial contrast echocardiography and tissue Doppler have recently been proposed to provide further, quantitative measures of myocardial viability assessment. Cardiac magnetic resonance (CMR) has become popular for the assessment of myocardial viability as it can assess cardiac function, volumes, myocardial scar, and perfusion with high-spatial resolution. Both 'delayed enhancement' CMR and dobutamine stress CMR have important roles in the assessment of patients with ischaemic cardiomyopathy. This article reviews the recent advances in both echocardiography and CMR for the clinical assessment of myocardial viability. It attempts to provide a pragmatic approach toward the patient-specific assessment of this important clinical problem.

Prospective study of tricuspid valve regurgitation associated with permanent leads in patients undergoing cardiac rhythm device implantation: Background, rationale, and design

PubMed Central

Dokainish, Hisham; Elbarasi, Esam; Masiero, Simona; Van de Heyning, Caroline; Brambatti, Michela; Ghazal, Sami; AL-Maashani, Said; Capucci, Alessandro; Buikema, Lisanne; Leong, Darryl; Shivalkar, Bharati; Saenen, Johan; Miljoen, Hielko; Morillo, Carlos; Divarakarmenon, Syam; Amit, Guy; Ribas, Sebastian; Brautigam, Aaron; Baiocco, Erika; Maolo, Alessandro; Romandini, Andrea; Maffei, Simone; Connolly, Stuart; Healey, Jeff

2015-01-01

Given the increasing numbers of cardiac device implantations worldwide, it is important to determine whether permanent endocardial leads across the tricuspid valve can promote tricuspid regurgitation (TR). Virtually all current data is retrospective, and indicates a signal of TR being increased after permanent lead implantation. However, the precise incidence of moderate or greater TR post-procedure, the exact mechanisms (mechanical, traumatic, functional), and the hemodynamic burden and clinical effects of this putative increase in TR, remain uncertain. We have therefore designed a multicenter, international, prospective study of 300 consecutive patients (recruitment completed, baseline data presented) who will undergo echocardiography and clinical assessment prior to, and at 1-year post device insertion. This prospective study will help determine whether cardiac device-associated TR is real, what are its potential mechanisms, and whether it has an important clinical impact on cardiac device patients. PMID:26779517

Dysregulated endocardial TGFβ signaling and mesenchymal transformation result in heart outflow tract septation failure.

PubMed

Ma, Mancheong; Li, Peng; Shen, Hua; Estrada, Kristine D; Xu, Jian; Kumar, S Ram; Sucov, Henry M

2016-01-01

Heart outflow tract septation in mouse embryos carrying mutations in retinoic acid receptor genes fails with complete penetrance. In this mutant background, ectopic TGFβ signaling in the distal outflow tract is responsible for septation failure, but it was uncertain what tissue was responsive to ectopic TGFβ and why this response interfered with septation. By combining RAR gene mutation with tissue-specific Cre drivers and a conditional type II TGFβ receptor (Tgfbr2) allele, we determined that ectopic activation of TGFβ signaling in the endocardium is responsible for septation defects. Ectopic TGFβ signaling results in ectopic mesenchymal transformation of the endocardium and thereby in improperly constituted distal OFT cushions. Our analysis highlights the interactions between myocardium, endocardium, and neural crest cells in outflow tract morphogenesis, and demonstrates the requirement for proper TGFβ signaling in outflow tract cushion organization and septation. Copyright © 2015. Published by Elsevier Inc.

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

PubMed

Almomani, Ahmed; Siddiqui, Khadija; Ahmad, Masood

2014-03-01

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

[Medical computer-aided detection method based on deep learning].

PubMed

Tao, Pan; Fu, Zhongliang; Zhu, Kai; Wang, Lili

2018-03-01

This paper performs a comprehensive study on the computer-aided detection for the medical diagnosis with deep learning. Based on the region convolution neural network and the prior knowledge of target, this algorithm uses the region proposal network, the region of interest pooling strategy, introduces the multi-task loss function: classification loss, bounding box localization loss and object rotation loss, and optimizes it by end-to-end. For medical image it locates the target automatically, and provides the localization result for the next stage task of segmentation. For the detection of left ventricular in echocardiography, proposed additional landmarks such as mitral annulus, endocardial pad and apical position, were used to estimate the left ventricular posture effectively. In order to verify the robustness and effectiveness of the algorithm, the experimental data of ultrasonic and nuclear magnetic resonance images are selected. Experimental results show that the algorithm is fast, accurate and effective.

Contrast echocardiography: new agents.

PubMed

Miller, Andrew P; Nanda, Navin C

2004-04-01

In this report, we review the history, rationale, current status and future directions of contrast agents in echocardiography. First, we discuss the historic development of contrast agents through a review of important physical principles of microbubbles in ultrasonography. Second, we identify attributes of an ideal contrast agent and review those that are currently available or in the "pipeline" for clinical use. Third, we review indications for contrast echocardiography, including endocardial border detection, perfusion quantification and reperfusion assessment, and validate these observations by comparisons with other imaging modalities. Then, we briefly review different methodologies of performing a contrast study, including interrupted, real-time and a hybrid modality. Finally, we identify novel future applications of the newest contrast agents. These newer concepts in contrast echocardiography should form a foundation for nearly limitless application of echocardiography in improved anatomical assessment, perfusion imaging and even special applications, such as detection of vascular inflammation and site-specific drug delivery.

[The complex origin of ventricular tachycardia after the total correction of tetralogy of Fallot].

PubMed

Ressia, L; Graffigna, A; Salerno-Uriarte, J A; Viganò, M

1993-09-01

Two patients underwent surgical treatment of ventricular tachycardia after repair of tetralogy of Fallot. Both patients had right bundle branch block, moderate pulmonary valve incompetence and right ventricular dilatation, and were refractory to electrophysiologically guided drug therapy. Both patients underwent intraoperative epicardial mapping, which located the arrhythmogenic focus on the right ventricular outflow tract, on the border of the previous ventriculotomy. In one patient removal of the previous scar and endocardial cryoablation was successful in ablating the arrhythmia. In the other, the same procedure was only temporarily effective. VT recurred and was subsequently identified at the superior border of the closed ventricular septal defect. It was ablated by means of transcatheter radiofrequency. While VT from foci located on the right ventricular free wall can be easily detected and ablated, septal origin of VT requires extensive preoperative and intraoperative electrophysiological evaluation and may necessitate combined surgical and transcatheter procedures.

Sequential Notch activation regulates ventricular chamber development

PubMed Central

D'Amato, Gaetano; Luxán, Guillermo; del Monte-Nieto, Gonzalo; Martínez-Poveda, Beatriz; Torroja, Carlos; Walter, Wencke; Bochter, Matthew S.; Benedito, Rui; Cole, Susan; Martinez, Fernando; Hadjantonakis, Anna-Katerina; Uemura, Akiyoshi; Jiménez-Borreguero, Luis J.; de la Pompa, José Luis

2016-01-01

Ventricular chambers are essential for the rhythmic contraction and relaxation occurring in every heartbeat throughout life. Congenital abnormalities in ventricular chamber formation cause severe human heart defects. How the early trabecular meshwork of myocardial fibres forms and subsequently develops into mature chambers is poorly understood. We show that Notch signalling first connects chamber endocardium and myocardium to sustain trabeculation, and later coordinates ventricular patterning and compaction with coronary vessel development to generate the mature chamber, through a temporal sequence of ligand signalling determined by the glycosyltransferase manic fringe (MFng). Early endocardial expression of MFng promotes Dll4–Notch1 signalling, which induces trabeculation in the developing ventricle. Ventricular maturation and compaction require MFng and Dll4 downregulation in the endocardium, which allows myocardial Jag1 and Jag2 signalling to Notch1 in this tissue. Perturbation of this signalling equilibrium severely disrupts heart chamber formation. Our results open a new research avenue into the pathogenesis of cardiomyopathies. PMID:26641715

How to Make a Heart Valve: From Embryonic Development to Bioengineering of Living Valve Substitutes

PubMed Central

MacGrogan, Donal; Luxán, Guillermo; Driessen-Mol, Anita; Bouten, Carlijn; Baaijens, Frank; de la Pompa, José Luis

2014-01-01

Cardiac valve disease is a significant cause of ill health and death worldwide, and valve replacement remains one of the most common cardiac interventions in high-income economies. Despite major advances in surgical treatment, long-term therapy remains inadequate because none of the current valve substitutes have the potential for remodeling, regeneration, and growth of native structures. Valve development is coordinated by a complex interplay of signaling pathways and environmental cues that cause disease when perturbed. Cardiac valves develop from endocardial cushions that become populated by valve precursor mesenchyme formed by an epithelial–mesenchymal transition (EMT). The mesenchymal precursors, subsequently, undergo directed growth, characterized by cellular compartmentalization and layering of a structured extracellular matrix (ECM). Knowledge gained from research into the development of cardiac valves is driving exploration into valve biomechanics and tissue engineering directed at creating novel valve substitutes endowed with native form and function. PMID:25368013

Regional distribution of T-tubule density in left and right atria in dogs.

PubMed

Arora, Rishi; Aistrup, Gary L; Supple, Stephen; Frank, Caleb; Singh, Jasleen; Tai, Shannon; Zhao, Anne; Chicos, Laura; Marszalec, William; Guo, Ang; Song, Long-Sheng; Wasserstrom, J Andrew

2017-02-01

The peculiarities of transverse tubule (T-tubule) morphology and distribution in the atrium-and how they contribute to excitation-contraction coupling-are just beginning to be understood. The objectives of this study were to determine T-tubule density in the intact, live right and left atria in a large animal and to determine intraregional differences in T-tubule organization within each atrium. Using confocal microscopy, T-tubules were imaged in both atria in intact, Langendorf-perfused normal dog hearts loaded with di-4-ANEPPS. T-tubules were imaged in large populations of myocytes from the endocardial surface of each atrium. Computerized data analysis was performed using a new MatLab (Mathworks, Natick, MA) routine, AutoTT. There was a large percentage of myocytes that had no T-tubules in both atria with a higher percentage in the right atrium (25.1%) than in the left atrium (12.5%) (P < .02). The density of transverse and longitudinal T-tubule elements was low in cells that did contain T-tubules, but there were no significant differences in density between the left atrial appendage, the pulmonary vein-posterior left atrium, the right atrial appendage, and the right atrial free wall. In contrast, there were significant differences in sarcomere spacing and cell width between different regions of the atria. There is a sparse T-tubule network in atrial myocytes throughout both dog atria, with significant numbers of myocytes in both atria-the right atrium more so than the left atrium-having no T-tubules at all. These regional differences in T-tubule distribution, along with differences in cell width and sarcomere spacing, may have implications for the emergence of substrate for atrial fibrillation. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Multi-view 3D echocardiography compounding based on feature consistency

NASA Astrophysics Data System (ADS)

Yao, Cheng; Simpson, John M.; Schaeffter, Tobias; Penney, Graeme P.

2011-09-01

Echocardiography (echo) is a widely available method to obtain images of the heart; however, echo can suffer due to the presence of artefacts, high noise and a restricted field of view. One method to overcome these limitations is to use multiple images, using the 'best' parts from each image to produce a higher quality 'compounded' image. This paper describes our compounding algorithm which specifically aims to reduce the effect of echo artefacts as well as improving the signal-to-noise ratio, contrast and extending the field of view. Our method weights image information based on a local feature coherence/consistency between all the overlapping images. Validation has been carried out using phantom, volunteer and patient datasets consisting of up to ten multi-view 3D images. Multiple sets of phantom images were acquired, some directly from the phantom surface, and others by imaging through hard and soft tissue mimicking material to degrade the image quality. Our compounding method is compared to the original, uncompounded echocardiography images, and to two basic statistical compounding methods (mean and maximum). Results show that our method is able to take a set of ten images, degraded by soft and hard tissue artefacts, and produce a compounded image of equivalent quality to images acquired directly from the phantom. Our method on phantom, volunteer and patient data achieves almost the same signal-to-noise improvement as the mean method, while simultaneously almost achieving the same contrast improvement as the maximum method. We show a statistically significant improvement in image quality by using an increased number of images (ten compared to five), and visual inspection studies by three clinicians showed very strong preference for our compounded volumes in terms of overall high image quality, large field of view, high endocardial border definition and low cavity noise.

Left ventricular hypertrophy in ascending aortic stenosis mice: anoikis and the progression to early failure

NASA Technical Reports Server (NTRS)

Ding, B.; Price, R. L.; Goldsmith, E. C.; Borg, T. K.; Yan, X.; Douglas, P. S.; Weinberg, E. O.; Bartunek, J.; Thielen, T.; Didenko, V. V.;

Myocardial wall thickening from gated magnetic resonance images using Laplace's equation

NASA Astrophysics Data System (ADS)

Prasad, M.; Ramesh, A.; Kavanagh, P.; Gerlach, J.; Germano, G.; Berman, D. S.; Slomka, P. J.

2009-02-01

The aim of our work is to present a robust 3D automated method for measuring regional myocardial thickening using cardiac magnetic resonance imaging (MRI) based on Laplace's equation. Multiple slices of the myocardium in short-axis orientation at end-diastolic and end-systolic phases were considered for this analysis. Automatically assigned 3D epicardial and endocardial boundaries were fitted to short-axis and long axis slices corrected for breathold related misregistration, and final boundaries were edited by a cardiologist if required. Myocardial thickness was quantified at the two cardiac phases by computing the distances between the myocardial boundaries over the entire volume using Laplace's equation. The distance between the surfaces was found by computing normalized gradients that form a vector field. The vector fields represent tangent vectors along field lines connecting both boundaries. 3D thickening measurements were transformed into polar map representation and 17-segment model (American Heart Association) regional thickening values were derived. The thickening results were then compared with standard 17-segment 6-point visual scoring of wall motion/wall thickening (0=normal; 5=greatest abnormality) performed by a consensus of two experienced imaging cardiologists. Preliminary results on eight subjects indicated a strong negative correlation (r=-0.8, p<0.0001) between the average thickening obtained using Laplace and the summed segmental visual scores. Additionally, quantitative ejection fraction measurements also correlated well with average thickening scores (r=0.72, p<0.0001). For segmental analysis, we obtained an overall correlation of -0.55 (p<0.0001) with higher agreement along the mid and apical regions (r=-0.6). In conclusion 3D Laplace transform can be used to quantify myocardial thickening in 3D.

Histophilosis as a Natural Disease.

PubMed

O'Toole, D; Sondgeroth, K S

2016-01-01

Histophilus somni is responsible for sporadic disease worldwide in cattle and, to a lesser extent, in small ruminants, bighorn sheep (Ovis canadensis), and North American bison (Bison bison). The importance of H. somni diseases can be attributed to improved clinical and laboratory recognition, combined with the growth in intensive management practices for cattle. Although outbreaks of bovine histophilosis can occur year-round, in northern and southern hemispheres, it is most frequent in late fall and early winter. Weather, stress, dietary changes, and comingling of cattle are likely to be major triggers for outbreaks. The most frequent clinical expressions of histophilosis include undifferentiated fever, fibrinosuppurative pneumonia, encephalitis-leptomeningitis, necrotizing myocarditis, and diffuse pleuritis. Neurological disease occurs either as thrombotic meningoencephalitis (TME) or as suppurative meningitis with ventriculitis. Acute myocarditis is characteristically necrotizing and generally involves one or both papillary muscles in the left ventricular myocardium. Biofilm-like aggregates of bacteria occur in capillaries and veins in myocardium, in the central nervous system, and on endocardial surfaces. H. somni is a component of bovine respiratory disease (BRD) complex. In our experience, it is most commonly diagnosed in subacute-to-chronic polymicrobial pulmonary infections in combination with Mannheimia haemolytica, Trueperella pyogenes, Pasteurella multocida, or Mycoplasma bovis. Other, less common forms of H. somni disease present as polyarthritis/tenosynovitis, abortion with placentitis and fetal septicemia, epididymitis-orchitis, and ocular infections. It is likely that H. somni is under-recognized clinically and diagnostically. Most state and provincial laboratories in North America rely on bacterial isolation to confirm infection. The use of more sensitive detection methods on field cases of histophilosis will help resolve the pathogenesis of H. somni in natural outbreaks, and whether the disease is as common elsewhere as it is in Canada.

Localization of premature ventricular contractions from the papillary muscles using the standard 12-lead electrocardiogram: a feasibility study using a novel cardiac isochrone positioning system.

PubMed

van Dam, Peter M; Boyle, Noel G; Laks, Michael M; Tung, Roderick

2016-12-01

The precise localization of the site of origin of a premature ventricular contraction (PVC) prior to ablation can facilitate the planning and execution of the electrophysiological procedure. In clinical practice, the targeted ablation site is estimated from the standard 12-lead ECG. The accuracy of this qualitative estimation has limitations, particularly in the localization of PVCs originating from the papillary muscles. Clinical available electrocardiographic imaging (ECGi) techniques that incorporate patient-specific anatomy may improve the localization of these PVCs, but require body surface maps with greater specificity for the epicardium. The purpose of this report is to demonstrate that a novel cardiac isochrone positioning system (CIPS) program can accurately detect the specific location of the PVC on the papillary muscle using only a 12-lead ECG. Cardiac isochrone positioning system uses three components: (i) endocardial and epicardial cardiac anatomy and torso geometry derived from MRI, (ii) the patient-specific electrode positions derived from an MRI model registered 3D image, and (iii) the 12-lead ECG. CIPS localizes the PVC origin by matching the anatomical isochrone vector with the ECG vector. The predicted PVC origin was compared with the site of successful ablation or stimulation. Three patients who underwent electrophysiological mapping and ablation of PVCs originating from the papillary muscles were studied. CIPS localized the PVC origin for all three patients to the correct papillary muscle and specifically to the base, mid, or apical region. A simplified form of ECGi utilizing only 12 standard electrocardiographic leads may facilitate accurate localization of the origin of papillary muscle PVCs. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For Permissions, please email: journals.permissions@oup.com.

Towards optical spectroscopic anatomical mapping (OSAM) for lesion validation in cardiac tissue (Conference Presentation)

NASA Astrophysics Data System (ADS)

Singh-Moon, Rajinder P.; Zaryab, Mohammad; Hendon, Christine P.

2017-02-01

Electroanatomical mapping (EAM) is an invaluable tool for guiding cardiac radiofrequency ablation (RFA) therapy. The principle roles of EAM is the identification of candidate ablation sites by detecting regions of abnormal electrogram activity and lesion validation subsequent to RF energy delivery. However, incomplete lesions may present interim electrical inactivity similar to effective treatment in the acute setting, despite efforts to reveal them with pacing or drugs, such as adenosine. Studies report that the misidentification and recovery of such lesions is a leading cause of arrhythmia recurrence and repeat procedures. In previous work, we demonstrated spectroscopic characterization of cardiac tissues using a fiber optic-integrated RF ablation catheter. In this work, we introduce OSAM (optical spectroscopic anatomical mapping), the application of this spectroscopic technique to obtain 2-dimensional biodistribution maps. We demonstrate its diagnostic potential as an auxiliary method for lesion validation in treated swine preparations. Endocardial lesion sets were created on fresh swine cardiac samples using a commercial RFA system. An optically-integrated catheter console fabricated in-house was used for measurement of tissue optical spectra between 600-1000nm. Three dimensional, Spatio-spectral datasets were generated by raster scanning of the optical catheter across the treated sample surface in the presence of whole blood. Tissue optical parameters were recovered at each spatial position using an inverse Monte Carlo method. OSAM biodistribution maps showed stark correspondence with gross examination of tetrazolium chloride stained tissue specimens. Specifically, we demonstrate the ability of OSAM to readily distinguish between shallow and deeper lesions, a limitation faced by current EAM techniques. These results showcase the OSAMs potential for lesion validation strategies for the treatment of cardiac arrhythmias.

Right Ventricular Strain, Torsion, and Dyssynchrony in Healthy Subjects using 3D Spiral Cine DENSE Magnetic Resonance Imaging

PubMed Central

Suever, Jonathan D; Wehner, Gregory J; Jing, Linyuan; Powell, David K; Hamlet, Sean M; Grabau, Jonathan D; Mojsejenko, Dimitri; Andres, Kristin N; Haggerty, Christopher M; Fornwalt, Brandon K

2017-01-01

Mechanics of the left ventricle (LV) are important indicators of cardiac function. The role of right ventricular (RV) mechanics is largely unknown due to the technical limitations of imaging its thin wall and complex geometry and motion. By combining 3D Displacement Encoding with Stimulated Echoes (DENSE) with a post-processing pipeline that includes a local coordinate system, it is possible to quantify RV strain, torsion, and synchrony. In this study, we sought to characterize RV mechanics in 50 healthy individuals and compare these values to their LV counterparts. For each cardiac frame, 3D displacements were fit to continuous and differentiable radial basis functions, allowing for the computation of the 3D Cartesian Lagrangian strain tensor at any myocardial point. The geometry of the RV was extracted via a surface fit to manually delineated endocardial contours. Throughout the RV, a local coordinate system was used to transform from a Cartesian strain tensor to a polar strain tensor. It was then possible to compute peak RV torsion as well as peak longitudinal and circumferential strain. A comparable analysis was performed for the LV. Dyssynchrony was computed from the standard deviation of regional activation times. Global circumferential strain was comparable between the RV and LV (−18.0% for both) while longitudinal strain was greater in the RV (−18.1% vs. −15.7%). RV torsion was comparable to LV torsion (6.2 vs. 7.1 degrees, respectively). Regional activation times indicated that the RV contracted later but more synchronously than the LV. 3D spiral cine DENSE combined with a post–processing pipeline that includes a local coordinate system can resolve both the complex geometry and 3D motion of the RV. PMID:28055859

Properties that influence the specific surface areas of carbon nanotubes and nanofibers.

PubMed

Birch, M Eileen; Ruda-Eberenz, Toni A; Chai, Ming; Andrews, Ronnee; Hatfield, Randal L

2013-11-01

Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer-Emmett-Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed.

Specific surface area of a crushed welded tuff before and after aqueous dissolution

USGS Publications Warehouse

Reddy, M.M.; Claassen, H.C.

1994-01-01

Specific surface areas were measured for several reference minerals (anorthoclase, labradorite and augite), welded tuff and stream sediments from Snowshoe Mountain, near Creede, Colorado. Crushed and sieved tuff had an unexpectedly small variation in specific surface area over a range of size fractions. Replicate surface area measurements of the largest and smallest tuff particle size fractions examined (1-0.3 mm and <0.212 mm) were 2.3 ?? 0.2 m2/g for each size fraction. Reference minerals prepared in the same way as the tuff had smaller specific surface areas than that of the tuff of the same size fraction. Higher than expected tuff specific surface areas appear to be due to porous matrix. Tuff, reacted in solutions with pH values from 2 to 6, had little change in specific surface area in comparison with unreacted tuff. Tuff, reacted with solutions having high acid concentrations (0.1 M hydrochloric acid or sulfuric-hydrofluoric acid), exhibited a marked increase in specific surface area compared to unreacted tuff. ?? 1994.

Lp-mixed affine surface area

NASA Astrophysics Data System (ADS)

Wang, Weidong; Leng, Gangsong

2007-11-01

According to the three notions of mixed affine surface area, Lp-affine surface area and Lp-mixed affine surface area proposed by Lutwak, in this article, we give the concept of ith Lp-mixed affine surface area such that the first and second notions of Lutwak are its special cases. Further, some Lutwak's results are extended associated with this concept. Besides, applying this concept, we establish an inequality for the volumes and dual quermassintegrals of a class of star bodies.

Assessing the Increase in Specific Surface Area for Electrospun Fibrous Network due to Pore Induction.

PubMed

Katsogiannis, Konstantinos Alexandros G; Vladisavljević, Goran T; Georgiadou, Stella; Rahmani, Ramin

2016-10-26

The effect of pore induction on increasing electrospun fibrous network specific surface area was investigated in this study. Theoretical models based on the available surface area of the fibrous network and exclusion of the surface area lost due to fiber-to-fiber contacts were developed. The models for calculation of the excluded area are based on Hertzian, Derjaguin-Muller-Toporov (DMT), and Johnson-Kendall-Roberts (JKR) contact models. Overall, the theoretical models correlated the network specific surface area to the material properties including density, surface tension, Young's modulus, Poisson's ratio, as well as network physical properties, such as density and geometrical characteristics including fiber radius, fiber aspect ratio and network thickness. Pore induction proved to increase the network specific surface area up to 52%, compared to the maximum surface area that could be achieved by nonporous fiber network with the same physical properties and geometrical characteristics. The model based on Johnson-Kendall-Roberts contact model describes accurately the fiber-to-fiber contact area under the experimental conditions used for pore generation. The experimental results and the theoretical model based on Johnson-Kendall-Roberts contact model show that the increase in network surface area due to pore induction can reach to up to 58%.

Long-term studies on the effects of nonvolatile organic compounds on porous media surface areas.

PubMed

Khachikian, Crist S; Harmon, Thomas C

2002-01-01

This paper investigates the long-term behavior of porous media contaminated by nonvolatile organic compounds (NVOC) in terms of specific interfacial surface area. Specifically, a natural sand, Moffett sand (MS), was contaminated with naphthalene and the surface area was measured repeatedly over time using nitrogen adsorption-desorption techniques. A field-contaminated sand affected by lamp-black material (LB) from former manufactured gas plant operations was also studied. Lampblack is a carbonaceous skeleton containing polycyclic aromatic hydrocarbons (PAHs) and other hydrocarbons. It is hypothesized that soils contaminated by these types of chemicals will exhibit significantly less surface area than their clean counterparts. The surface areas for the contaminated MS samples increased toward their clean-MS values during the 700-h aging period, but achieved the clean values only after pentane extraction or heating at 60 degrees C. Heating at 50 degrees C failed to achieve a similar recovery of the clean-MS surface area value. Nonspecific mass loss tracked the increase in surface area as indirect evidence that naphthalene loss was the cause of the surface area increase. For the LB samples, aging at 100 degrees C produced a slight decrease in surface area and mass while aging at 250 degrees C caused the surface area to increase roughly threefold while the mass decreased by approximately 1%. These results suggest that, under moderate heating and over the time scale of this investigation, there is a redistribution of the complex contaminant mixture on the solid matrix. Greater temperatures remove mass more efficiently and therefore exhibited the surface area increase expected in this experiment.

The surface area of soil organic matter

USGS Publications Warehouse

Chiou, C.T.; Lee, J.-F.; Boyd, S.A.

1990-01-01

The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.

Endo-epicardial ablation of ventricular arrhythmias in the left ventricle with the Remote Magnetic Navigation System and the 3.5-mm open irrigated magnetic catheter: results from a large single-center case-control series.

PubMed

Di Biase, Luigi; Santangeli, Pasquale; Astudillo, Vladimir; Conti, Sergio; Mohanty, Prasant; Mohanty, Sanghamitra; Sanchez, Javier E; Horton, Rodney; Thomas, Barbara; Burkhardt, J David; Natale, Andrea

2010-08-01

Remote magnetic navigation (RMN) has been reported as a feasible and safe mapping and ablation system for treatment of ventricular arrhythmias (VAs). However, the reported success rates have been limited with the 4- and 8-mm catheter tips. This study sought to report the results in a large series of consecutive patients undergoing radiofrequency (RF) catheter ablation of VAs using the RMN with the 3.5-mm magnetic open-irrigated-tip catheter (OIC). A total of 110 consecutive patients with a clinical history of left VA were included in the study. In all cases, an OIC was utilized for mapping and ablation. When ablation with the RMN catheters failed, a manual OIC was used to eliminate the VA. Postablation pacing maneuvers and isoproterenol were used to verify the inducibility of the VAs. Outcomes were compared with those of a group of 92 consecutive patients undergoing manual ablation by the same operator. Mapping and ablation with the magnetic OIC were performed in all 110 patients with VA. Ischemic cardiomyopathy was present in 33 (30%), nonischemic in 14 (13%), and in 63 (57%) patients no structural heart disease was present. Endocardial mapping was performed in all patients, whereas both endocardial and epicardial mapping were performed in 36 (33%) patients. Compared with manual ablation, RMN was associated with a longer procedural time (2.9 +/- 1.2 hours vs. 3.3 +/- 1.1 hours, P = 0.004) and RF time (24 +/- 12 minutes vs. 33 +/- 18 minutes, P = 0.005), whereas fluoroscopic time was significantly shorter (35 +/- 22 minutes vs. 26 +/- 14 minutes, P = 0.033). During the procedures, crossover to manual ablation was required in 15 patients (14%). At 11.7 +/- 2.1 months of follow-up in the study group and 18.7 +/- 3.7 months in the manual ablation group, 85% and 86% (P = 0.817) of patients, respectively, were free of VA. This large series of consecutive patients demonstrates that OIC ablation using RMN is effective for the treatment of left VAs. Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Assessment of geometrical characteristics of dental endodontic micro-instruments utilizing X-ray micro computed tomography

PubMed Central

Al JABBARI, Youssef S.; TSAKIRIDIS, Peter; ELIADES, George; AL-HADLAQ, Solaiman M.; ZINELIS, Spiros

2012-01-01

Objective The aim of this study was to quantify the surface area, volume and specific surface area of endodontic files employing quantitative X-ray micro computed tomography (mXCT). Material and Methods Three sets (six files each) of the Flex-Master Ni-Ti system (Nº 20, 25 and 30, taper .04) were utilized in this study. The files were scanned by mXCT. The surface area and volume of all files were determined from the cutting tip up to 16 mm. The data from the surface area, volume and specific area were statistically evaluated using the one-way ANOVA and SNK multiple comparison tests at α=0.05, employing the file size as a discriminating variable. The correlation between the surface area and volume with nominal ISO sizes were tested employing linear regression analysis. Results The surface area and volume of Nº 30 files showed the highest value followed by Nº 25 and Nº 20 and the differences were statistically significant. The Nº 20 files showed a significantly higher specific surface area compared to Nº 25 and Nº 30. The increase in surface and volume towards higher file sizes follows a linear relationship with the nominal ISO sizes (r2=0.930 for surface area and r2=0.974 for volume respectively). Results indicated that the surface area and volume demonstrated an almost linear increase while the specific surface area exhibited an abrupt decrease towards higher sizes. Conclusions This study demonstrates that mXCT can be effectively applied to discriminate very small differences in the geometrical features of endodontic micro-instruments, while providing quantitative information for their geometrical properties. PMID:23329248

A Mathematical Method to Calculate Tumor Contact Surface Area: An Effective Parameter to Predict Renal Function after Partial Nephrectomy.

PubMed

Hsieh, Po-Fan; Wang, Yu-De; Huang, Chi-Ping; Wu, Hsi-Chin; Yang, Che-Rei; Chen, Guang-Heng; Chang, Chao-Hsiang

2016-07-01

We proposed a mathematical formula to calculate contact surface area between a tumor and renal parenchyma. We examined the applicability of using contact surface area to predict renal function after partial nephrectomy. We performed this retrospective study in patients who underwent partial nephrectomy between January 2012 and December 2014. Based on abdominopelvic computerized tomography or magnetic resonance imaging, we calculated the contact surface area using the formula (2*π*radius*depth) developed by integral calculus. We then evaluated the correlation between contact surface area and perioperative parameters, and compared contact surface area and R.E.N.A.L. (Radius/Exophytic/endophytic/Nearness to collecting system/Anterior/Location) score in predicting a reduction in renal function. Overall 35, 26 and 45 patients underwent partial nephrectomy with open, laparoscopic and robotic approaches, respectively. Mean ± SD contact surface area was 30.7±26.1 cm(2) and median (IQR) R.E.N.A.L. score was 7 (2.25). Spearman correlation analysis showed that contact surface area was significantly associated with estimated blood loss (p=0.04), operative time (p=0.04) and percent change in estimated glomerular filtration rate (p <0.001). On multivariate analysis contact surface area and R.E.N.A.L. score independently affected percent change in estimated glomerular filtration rate (p <0.001 and p=0.03, respectively). On ROC curve analysis contact surface area was a better independent predictor of a greater than 10% change in estimated glomerular filtration rate compared to R.E.N.A.L. score (AUC 0.86 vs 0.69). Using this simple mathematical method, contact surface area was associated with surgical outcomes. Compared to R.E.N.A.L. score, contact surface area was a better predictor of functional change after partial nephrectomy. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Influence of specific surface area on coal dust explosibility using the 20-L chamber.

PubMed

Zlochower, Isaac A; Sapko, Michael J; Perera, Inoka E; Brown, Connor B; Harris, Marcia L; Rayyan, Naseem S

2018-07-01

The relationship between the explosion inerting effectiveness of rock dusts on coal dusts, as a function of the specific surface area (cm 2 /g) of each component is examined through the use of 20-L explosion chamber testing. More specifically, a linear relationship is demonstrated for the rock dust to coal dust (or incombustible to combustible) content of such inerted mixtures with the specific surface area of the coal and the inverse of that area of the rock dust. Hence, the inerting effectiveness, defined as above, is more generally linearly dependent on the ratio of the two surface areas. The focus on specific surface areas, particularly of the rock dust, provide supporting data for minimum surface area requirements in addition to the 70% less than 200 mesh requirement specified in 30 CFR 75.2.

30 CFR 905.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface coal mining operations. 905.764 Section 905.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE CALIFORNIA § 905.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface Coal...

30 CFR 910.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface coal mining operations. 910.764 Section 910.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE GEORGIA § 910.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface Coal...

30 CFR 912.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface coal mining operations. 912.764 Section 912.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE IDAHO § 912.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface Coal...

30 CFR 903.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface coal mining operations. 903.764 Section 903.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE ARIZONA § 903.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface Coal...

The use of total lake-surface area as an indicator of climatic change: Examples from the Lahontan basin

USGS Publications Warehouse

Benson, L.V.; Paillet, Frederick L.

1989-01-01

Variation in the size of lakes in the Lahontan basin is topographically constrained. River diversion also has played a major role in regulating lake size in Lahontan subbasins. The proper gage of lake response to change in the hydrologic balance is neither lake depth (level) nor lake volume but instead lake-surface area. Normalization of surface area is necessary when comparing surface areas of lakes in basins having different topographies. To a first approximation, normalization can be accomplished by dividing the paleosurface area of a lake by its mean-historical, reconstructed surface area. ?? 1989.

Molar crown and root size relationship in anthropoid primates.

PubMed

Kupczik, Kornelius; Olejniczak, Anthony J; Skinner, Matthew M; Hublin, Jean-Jacques

2009-01-01

Mandibular corpus form is thought to reflect masticatory function and the size of the dentition, but there is no universal association between crown dimensions and corpus size across anthropoids. Previous research was based on the assumption that crown size is an appropriate proxy for overall tooth size, but this hypothesis remains largely untested. This study assesses the relationship between the volume and surface area of molar crowns and roots by examining two main hypotheses: (1) crown size correlates significantly with root size, and (2) the proportion of root-to-crown surface area is related to dietary proclivity. Permanent M2s (n=58) representing 19 anthropoid species were CT scanned and the volume and surface area of the crown and root were measured. Interspecific correlation and regression analyses reveal significant isometric relationships between crown and root volume and a positive allometric relationship between root and crown surface area (i.e. as crown surface area increases, root surface area becomes disproportionately greater). Intraspecifically, crown and root surface area correlate significantly in some species where such analyses were possible. In general, hard object feeders exhibit relatively larger root surface area per unit crown surface area compared to soft and tough object feeders. The results also show that despite differences in food specialization closely related species have similar root-to-crown surface area proportions, thus indicating a strong phylogenetic influence. Since it is possible that, at least in some species, crown and root size vary independently, future studies should elucidate the relationship between tooth root size and mandible form. Copyright (c) 2009 S. Karger AG, Basel.

Age Differences in Prefrontal Surface Area and Thickness in Middle Aged to Older Adults.

PubMed

Dotson, Vonetta M; Szymkowicz, Sarah M; Sozda, Christopher N; Kirton, Joshua W; Green, Mackenzie L; O'Shea, Andrew; McLaren, Molly E; Anton, Stephen D; Manini, Todd M; Woods, Adam J

2015-01-01

Age is associated with reductions in surface area and cortical thickness, particularly in prefrontal regions. There is also evidence of greater thickness in some regions at older ages. Non-linear age effects in some studies suggest that age may continue to impact brain structure in later decades of life, but relatively few studies have examined the impact of age on brain structure within middle-aged to older adults. We investigated age differences in prefrontal surface area and cortical thickness in healthy adults between the ages of 51 and 81 years. Participants received a structural 3-Tesla magnetic resonance imaging scan. Based on a priori hypotheses, primary analyses focused on surface area and cortical thickness in the dorsolateral prefrontal cortex, anterior cingulate cortex, and orbitofrontal cortex. We also performed exploratory vertex-wise analyses of surface area and cortical thickness across the entire cortex. We found that older age was associated with smaller surface area in the dorsolateral prefrontal and orbitofrontal cortices but greater cortical thickness in the dorsolateral prefrontal and anterior cingulate cortices. Vertex-wise analyses revealed smaller surface area in primarily frontal regions at older ages, but no age effects were found for cortical thickness. Results suggest age is associated with reduced surface area but greater cortical thickness in prefrontal regions during later decades of life, and highlight the differential effects age has on regional surface area and cortical thickness.

Surface Area, and Oxidation Effects on Nitridation Kinetics of Silicon Powder Compacts

NASA Technical Reports Server (NTRS)

Bhatt, R. T.; Palczer, A. R.

1998-01-01

Commercially available silicon powders were wet-attrition-milled from 2 to 48 hr to achieve surface areas (SA's) ranging from 1.3 to 70 sq m/g. The surface area effects on the nitridation kinetics of silicon powder compacts were determined at 1250 or 1350 C for 4 hr. In addition, the influence of nitridation environment, and preoxidation on nitridation kinetics of a silicon powder of high surface area (approximately equals 63 sq m/g) was investigated. As the surface area increased, so did the percentage nitridation after 4 hr in N2 at 1250 or 1350 C. Silicon powders of high surface area (greater than 40 sq m/g) can be nitrided to greater than 70% at 1250 C in 4 hr. The nitridation kinetics of the high-surface-area powder compacts were significantly delayed by preoxidation treatment. Conversely, the nitridation environment had no significant influence on the nitridation kinetics of the same powder. Impurities present in the starting powder, and those accumulated during attrition milling, appeared to react with the silica layer on the surface of silicon particles to form a molten silicate layer, which provided a path for rapid diffusion of nitrogen and enhanced the nitridation kinetics of high surface area silicon powder.

In Situ Aerosol Profile Measurements and Comparisons with SAGE 3 Aerosol Extinction and Surface Area Profiles at 68 deg North

NASA Technical Reports Server (NTRS)

2005-01-01

Under funding from this proposal three in situ profile measurements of stratospheric sulfate aerosol and ozone were completed from balloon-borne platforms. The measured quantities are aerosol size resolved number concentration and ozone. The one derived product is aerosol size distribution, from which aerosol moments, such as surface area, volume, and extinction can be calculated for comparison with SAGE III measurements and SAGE III derived products, such as surface area. The analysis of these profiles and comparison with SAGE III extinction measurements and SAGE III derived surface areas are provided in Yongxiao (2005), which comprised the research thesis component of Mr. Jian Yongxiao's M.S. degree in Atmospheric Science at the University of Wyoming. In addition analysis continues on using principal component analysis (PCA) to derive aerosol surface area from the 9 wavelength extinction measurements available from SAGE III. Ths paper will present PCA components to calculate surface area from SAGE III measurements and compare these derived surface areas with those available directly from in situ size distribution measurements, as well as surface areas which would be derived from PCA and Thomason's algorithm applied to the four wavelength SAGE II extinction measurements.

Urban Heat Island ın Ankara

NASA Astrophysics Data System (ADS)

Yılmaz, Erkan

2016-04-01

In this study, the seasonal variation of the surface temperature of Ankara urban area and its enviroment have been analyzed by using Landsat 7 image. The Landsat 7 images of each month from 2007 to 2011 have been used to analyze the annually changes of the surface temperature. The land cover of the research area was defined with supervised classification method on the basis of the satellite image belonging to 2008 July. After determining the surface temperatures from 6-1 bands of satellite images, the monthly mean surface temperatures were calculated for land cover classification for the period between 2007 and 2011. According to the results obtained, the surface temperatures are high in summer and low in winter from the airtemperatures. all satellite images were taken at 10:00 am, it is found that urban areas are cooler than rural areas at 10:00 am. Regarding the land cover classification, the water surfaces are the coolest surfaces during the whole year.The warmest areas are the grasslands and dry farming areas. While the parks are warmer than the urban areas during the winter, during the summer they are cooler than artificial land covers. The urban areas with higher building density are the cooler surfaces after water bodies.

Surface areas of fractally rough particles studied by scattering

NASA Astrophysics Data System (ADS)

Hurd, Alan J.; Schaefer, Dale W.; Smith, Douglas M.; Ross, Steven B.; Le Méhauté, Alain; Spooner, Steven

1989-05-01

The small-angle scattering from fractally rough surfaces has the potential to give information on the surface area at a given resolution. By use of quantitative neutron and x-ray scattering, a direct comparison of surface areas of fractally rough powders was made between scattering and adsorption techniques. This study supports a recently proposed correction to the theory for scattering from fractal surfaces. In addition, the scattering data provide an independent calibration of molecular adsorbate areas.

Morphological abnormalities in prefrontal surface area and thalamic volume in attention deficit/hyperactivity disorder.

PubMed

Batty, Martin J; Palaniyappan, Lena; Scerif, Gaia; Groom, Madeleine J; Liddle, Elizabeth B; Liddle, Peter F; Hollis, Chris

2015-08-30

Although previous morphological studies have demonstrated abnormalities in prefrontal cortical thickness in children with attention deficit/hyperactivity disorder (ADHD), studies investigating cortical surface area are lacking. As the development of cortical surface is closely linked to the establishment of thalam-ocortical connections, any abnormalities in the structure of the thalamus are likely to relate to altered cortical surface area. Using a clinically well-defined sample of children with ADHD (n = 25, 1 female) and typically developing controls (n = 24, 1 female), we studied surface area across the cortex to determine whether children with ADHD had reduced thalamic volume that related to prefrontal cortical surface area. Relative to controls, children with ADHD had a significant reduction in thalamic volume and dorsolateral prefrontal cortical area in both hemispheres. Furthermore, children with ADHD with smaller thalamic volumes were found to have greater reductions in surface area, a pattern not evident in the control children. Our results are further evidence of reduced lateral prefrontal cortical area in ADHD. Moreover, for the first time, we have also shown a direct association between thalamic anatomy and frontal anatomy in ADHD, suggesting the pathophysiological process that alters surface area maturation is likely to be linked to the development of the thalamus. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Space filling minimal surfaces and sphere packings

NASA Astrophysics Data System (ADS)

Elser, Veit

1994-05-01

A space filling minimal surface is defined to be any embedded minimal surface without boundary with the property that the area and genus enclosed by any large spherical region scales in proportion to the volume of the region. The triply periodic minimal surfaces are one realization, but not necessarily the only one. By using the genus per unit volume of the surface, a meaningful comparison of surface areas can be made even in cases where there is no unit cell. Of the known periodic minimal surfaces this measure of the surface area is smallest for Schoen's FRD surface. This surface is one of several that is closely related to packings of spheres. Its low area is largely due to the fact that the corresponding sphere packing (fcc) has the maximal kissing number.

Characterization of the Left-Sided Substrate in Arrhythmogenic Right Ventricular Cardiomyopathy.

PubMed

Berte, Benjamin; Denis, Arnaud; Amraoui, Sana; Yamashita, Seigo; Komatsu, Yuki; Pillois, Xavier; Sacher, Frédéric; Mahida, Saagar; Wielandts, Jean-Yves; Sellal, Jean-Marc; Frontera, Antonio; Al Jefairi, Nora; Derval, Nicolas; Montaudon, Michel; Laurent, François; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre; Cochet, Hubert

2015-12-01

The correlates of left ventricular (LV) substrate in arrhythmogenic right ventricular (RV) cardiomyopathy are largely unknown. Thirty-two patients with arrhythmogenic RV cardiomyopathy (47±14 years; 6 women) were included. RV and LV dysplasia were defined from multidetector computed tomography and cardiac magnetic resonance imaging. Arrhythmias were characterized as right-sided or left-sided on 12-lead ECG recordings at baseline and during isoproterenol testing. In 14 patients, the imaging substrate was compared with voltage mapping and local abnormal ventricular activity. Imaging abnormalities were found in 32 (100%) and 21 (66%) patients on the RV and LV, respectively, intramyocardial fat on multidetector computed tomography being the most sensitive feature. LV involvement related to none of the Task Force criteria. Right-sided arrhythmias were more frequent than left-sided arrhythmias (P=0.003) although the latter were more frequent in case of LV involvement (P=0.02). The agreement between low voltage and fat on multidetector computed tomography was high on the RV when using either endocardial unipolar or epicardial bipolar data (κ=0.82 and κ=0.78, respectively) but lower on the LV (κ=0.54 for epicardial bipolar). LV local abnormal ventricular activity was found in all patients with LV involvement, and none of the others. The density of local abnormal ventricular activity within fat areas was similar between the RV and LV (P=0.57). LV substrate is frequent in arrhythmogenic RV cardiomyopathy, but poorly identified by current diagnostic strategies. Left-sided arrhythmias are more frequent in case of LV involvement. LV fat hosts the same density of local abnormal ventricular activity as RV fat, but is less efficiently detected by voltage mapping. These results support the need for alternative diagnostic strategies to identify LV dysplasia. © 2015 American Heart Association, Inc.

Cellular mechanism underlying hypothermia-induced ventricular tachycardia/ventricular fibrillation in the setting of early repolarization and the protective effect of quinidine, cilostazol, and milrinone.

PubMed

Gurabi, Zsolt; Koncz, István; Patocskai, Bence; Nesterenko, Vladislav V; Antzelevitch, Charles

2014-02-01

Hypothermia has been reported to induce ventricular tachycardia and fibrillation (VT/VF) in patients with early repolarization (ER) pattern. This study examines the cellular mechanisms underlying VT/VF associated with hypothermia in an experimental model of ER syndrome and examines the effectiveness of quinidine, cilostazol, and milrinone to prevent hypothermia-induced arrhythmias. Transmembrane action potentials were simultaneously recorded from 2 epicardial and 1 endocardial site of coronary-perfused canine left ventricular wedge preparations, together with a pseudo-ECG. A combination of NS5806 (3-10 μmol/L) and verapamil (1 μmol/L) was used to pharmacologically model the genetic mutations responsible for ER syndrome. Acetylcholine (3 μmol/L) was used to simulate increased parasympathetic tone, which is known to promote ER. In controls, lowering the temperature of the coronary perfusate to induce mild hypothermia (32°C-34°C) resulted in increased J-wave area on the ECG and accentuated epicardial action potential notch but no arrhythmic activity. In the setting of ER, hypothermia caused further accentuation of the epicardial action potential notch, leading to loss of the action potential dome at some sites but not others, thus creating the substrate for development of phase 2 reentry and VT/VF. Addition of the transient outward current antagonist quinidine (5 μmol/L) or the phosphodiesterase III inhibitors cilostazol (10 μmol/L) or milrinone (5 μmol/L) diminished the ER manifestations and prevented the hypothermia-induced phase 2 reentry and VT/VF. Hypothermia leads to VT/VF in the setting of ER by exaggerating repolarization abnormalities, leading to development of phase 2 reentry. Quinidine, cilostazol, and milrinone suppress the hypothermia-induced VT/VF by reversing the repolarization abnormalities.

Cellular Mechanism Underlying Hypothermia-Induced VT/VF in the Setting of Early Repolarization and the Protective Effect of Quinidine, Cilostazol and Milrinone

PubMed Central

Gurabi, Zsolt; Koncz, István; Patocskai, Bence; Nesterenko, Vladislav V.; Antzelevitch, Charles

2014-01-01

Background Hypothermia has been reported to induce ventricular tachycardia and fibrillation (VT/VF) in patients with early repolarization (ER) pattern. This study examines the cellular mechanisms underlying VT/VF associated with hypothermia in an experimental model of ER syndrome (ERS) and examines the effectiveness of quinidine, cilostazol and milrinone to prevent hypothermia-induced arrhythmias. Method and Results Transmembrane action potentials (AP) were simultaneously recorded from 2 epicardial and 1 endocardial site of coronary-perfused canine left-ventricular wedge preparations, together with a pseudo-ECG. A combination of NS5806 (3–10 µM) and verapamil (1µM) was used to pharmacologically model the genetic mutations responsible for ERS. Acetylcholine (3µM) was used to simulate increased parasympathetic tone, which is known to promote ER. In control, lowering the temperature of the coronary perfusate to induce mild hypothermia (32°C-34°C) resulted in increased J wave area on the ECG and accentuated epicardial AP notch but no arrhythmic activity. In the setting of ER, hypothermia caused further accentuation of the epicardial AP notch, leading to loss of the AP dome at some sites but not others, thus creating the substrate for development of phase-2-reentry and VT/VF. Addition of the Ito antagonist quinidine (5 µM) or the phosphodiesterase III inhibitors cilostazol (10 µM) or milrinone (5 µM), diminished the ER manifestations and prevented the hypothermia-induced phase 2 reentry and VT/VF. Conclusions Hypothermia leads to VT/VF in the setting of ER by exaggerating repolarization abnormalities, leading to development of phase-2-reentry. Quinidine, cilostazol and milrinone suppress the hypothermia-induced VT/VF by reversing the repolarization abnormalities. PMID:24429494

Ultrasound contrast and real-time perfusion in conjunction with supine bicycle stress echocardiography for comprehensive evaluation of surgically corrected congenital heart disease.

PubMed

Kutty, Shelby; Olson, Joan; Danford, Christopher J; Sandene, Erin K; Xie, Feng; Fletcher, Scott E; Erickson, Christopher C; Kugler, John D; Danford, David A; Porter, Thomas R

2012-06-01

We sought to evaluate the efficacy of ultrasound contrast (UC) and low mechanical index real-time perfusion (RTP) in the haemodynamic and anatomic assessment of repaired congenital heart disease (CHD) at rest and during supine bicycle stress echocardiography (BSE). Patients with CHD (n = 51, median age 21.5 years) were prospectively studied. All had compromised image quality, 20 (39%) had arrhythmias, and 10 (20%) had pacemakers. RTP was performed at rest and during BSE using Definity and Contrast Pulse Sequencing, with assessment of Doppler pressure gradients. Diagnoses included tetralogy of Fallot (n = 27), transposition of the great arteries (TGA) atrial switch (n = 10), TGA arterial switch (n = 2), aortic valve disease (n = 4), Fontan (n = 4), and Kawasaki disease (n = 4). UC with RTP improved endocardial border definition, with increased number of left ventricular (LV) and right ventricular (RV) segments visualized at rest (P < 0.0001) and during stress. LV ejection fraction (EF) and RV fractional area change (FAC) were measurable at rest and peak stress, RV FAC correlating closely with same-day magnetic resonance EFs (r = 0.72; P < 0.001). UC enhanced Doppler signals, enabling subpulmonary ventricular systolic pressure measurements at rest and stress. In six patients, marked elevations of subpulmonary ventricular systolic pressure were detected with UC during BSE, and quantifiable ventricular dysfunction. No adverse events occurred, other than transient low back pain in one patient. UC at rest and with supine BSE enables safe and comprehensive assessment of anatomy, haemodynamics, and biventricular functional and perfusion reserve in adolescents and young adults with surgically modified CHD.

Importance of Pulmonary Vein Preferential Fibrosis for Atrial Fibrillation Promotion in Hypertensive Rat Hearts.

PubMed

Iwasaki, Yu-Ki; Yamashita, Takeshi; Sekiguchi, Akiko; Hayami, Noriyuki; Shimizu, Wataru

2016-06-01

Hypertension is one of the independent risk factors for atrial fibrillation (AF). Pulmonary veins (PVs) play an important role as the substrate for AF and triggers of AF. The purpose of this study was to determine the structural remodelling of the PVs and its effect on promoting AF in hypertensive (HT) rat hearts. Eighteen-week-old Dahl salt-sensitive HT rats and their controls were used for histological and immunohistological analyses, and electrophysiological studies were performed in Langendorff perfused hearts. Masson-trichrome staining revealed that hypertension significantly increased the fibrosis in the PVs, particularly in subendocardial and perivascular areas, compared with that in control rats, however, at this early stage of hypertension, left atrial fibrosis was not prominent. In the HT rat hearts with PVs, electrical stimulation significantly increased the number of repetitive atrial firing and atrial tachycardia inducibility, which significantly diminished after the excision of the PVs. An immunofluorescent analysis revealed that HT rats had PV specific endocardial smooth muscle actin (αSMA)-positive cells with remarkable proliferation of platelet-derived growth factor (PDGF)-C and vascular endothelial growth factor (VEGF), which was lacking in the left atrial structures of the control and the HT rats. Pretreatment with imatinib, a PDGF receptor activity blocker, in HT rats reduced the αSMA-positive cell proliferation and fibrosis in the PVs and also induced a significant reduction in VEGF expression. Also, the drug pretreatment effectively prevented repetitive atrial firing promotion without affecting the blood pressure. PV preferential fibrosis might play an important role in the arrhythmogenic substrate of AF in HT rat hearts. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

33 CFR 334.200 - Chesapeake Bay, Point Lookout to Cedar Point; aerial and surface firing range and target area, U...

Code of Federal Regulations, 2011 CFR

2011-07-01

... Cedar Point; aerial and surface firing range and target area, U.S. Naval Air Station, Patuxent River... Chesapeake Bay, Point Lookout to Cedar Point; aerial and surface firing range and target area, U.S. Naval Air...) The regulations. (i) Through navigation of surface craft outside the target areas will be permitted at...

Chemical weathering rates of a soil chronosequence on granitic alluvium: I. Quantification of mineralogical and surface area changes and calculation of primary silicate reaction rates

USGS Publications Warehouse

White, A.F.; Blum, A.E.; Schulz, M.S.; Bullen, T.D.; Harden, J.W.; Peterson, M.L.

1996-01-01

Mineral weathering rates are determined for a series of soils ranging in age from 0.2-3000 Ky developed on alluvial terraces near Merced in the Central Valley of California. Mineralogical and elemental abundances exhibit time-dependent trends documenting the chemical evolution of granitic sand to residual kaolinite and quartz. Mineral losses with time occur in the order: hornblende > plagioclase > K-feldspar. Maximum volume decreases of >50% occur in the older soils. BET surface areas of the bulk soils increase with age, as do specific surface areas of aluminosilicate mineral fractions such as plagioclase, which increases from 0.4-1.5 m2 g-1 over 600 Ky. Quartz surface areas are lower and change less with time (0.11-0.23 m2 g-1). BET surface areas correspond to increasing external surface roughness (?? = 10-600) and relatively constant internal surface area (??? 1.3 m2 g-1). SEM observations confirm both surface pitting and development of internal porosity. A numerical model describes aluminosilicate dissolution rates as a function of changes in residual mineral abundance, grain size distributions, and mineral surface areas with time. A simple geometric treatment, assuming spherical grains and no surface roughness, predicts average dissolution rates (plagioclase, 10-17.4; K-feldspar, 10-17.8; and hornblende, 10-17.5 mol cm-1 s-1) that are constant with time and comparable to previous estimates of soil weathering. Average rates, based on BET surface area measurements and variable surface roughnesses, are much slower (plagioclase, 10-19.9; K-feldspar, 10-20.5; and hornblende 10-20.1 mol cm-2 s-1). Rates for individual soil horizons decrease by a factor of 101.5 over 3000 Ky indicating that the surface reactivities of minerals decrease as the physical surface areas increase. Rate constants based on BET estimates for the Merced soils are factors of 103-104 slower than reported experimental dissolution rates determined from freshly prepared silicates with low surface roughness (?? <10). This study demonstrates that the utility of experimental rate constants to predict weathering in soils is limited without consideration of variable surface areas and processes that control the evolution of surface reactivity with time.

Integrated Assessment of Left Ventricular Electrical Activation and Myocardial Strain Mapping in Heart Failure Patients: A Holistic Diagnostic Approach for Endocardial Cardiac Resynchronization Therapy, Ablation of Ventricular Tachycardia, and Biological Therapy.

PubMed

Maffessanti, Francesco; Prinzen, Frits W; Conte, Giulio; Regoli, François; Caputo, Maria Luce; Suerder, Daniel; Moccetti, Tiziano; Faletra, Francesco; Krause, Rolf; Auricchio, Angelo

2018-01-01

This study sought to test the accuracy of strain measurements based on anatomo-electromechanical mapping (AEMM) measurements compared with magnetic resonance imaging (MRI) tagging, to evaluate the diagnostic value of AEMM-based strain measurements in the assessment of myocardial viability, and the additional value of AEMM over peak-to-peak local voltages. The in vivo identification of viable tissue, evaluation of mechanical contraction, and simultaneous left ventricular activation is currently achieved using multiple complementary techniques. In 33 patients, AEMM maps (NOGA XP, Biologic Delivery Systems, Division of Biosense Webster, a Johnson & Johnson Company, Irwindale, California) and MRI images (Siemens 3T, Siemens Healthcare, Erlangen, Germany) were obtained within 1 month. MRI tagging was used to determine circumferential strain (E cc ) and delayed enhancement to obtain local scar extent (%). Custom software was used to measure E cc and local area strain (LAS) from the motion field of the AEMM catheter tip. Intertechnique agreement for E cc was good (R 2  = 0.80), with nonsignificant bias (0.01 strain units) and narrow limits of agreement (-0.03 to 0.06). Scar segments showed lower absolute strain amplitudes compared with nonscar segments: E cc (median [first to third quartile]: nonscar -0.10 [-0.15 to -0.06] vs. scar -0.04 [-0.06 to -0.02]) and LAS (-0.20 [-0.27 to -0.14] vs. -0.09 [-0.14 to -0.06]). AEMM strains accurately discriminated between scar and nonscar segments, in particular LAS (area under the curve: 0.84, accuracy = 0.76), which was superior to peak-to-peak voltages (nonscar 9.5 [6.5 to 13.3] mV vs. scar 5.6 [3.4 to 8.3] mV; area under the curve: 0.75). Combination of LAS and peak-to-peak voltages resulted in 86% accuracy. An integrated AEMM approach can accurately determine local deformation and correlates with the scar extent. This approach has potential immediate application in the diagnosis, delivery of intracardiac therapies, and their intraprocedural evaluation. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

New model for estimating the relationship between surface area and volume in the human body using skeletal remains.

PubMed

Kasabova, Boryana E; Holliday, Trenton W

2015-04-01

A new model for estimating human body surface area and body volume/mass from standard skeletal metrics is presented. This model is then tested against both 1) "independently estimated" body surface areas and "independently estimated" body volume/mass (both derived from anthropometric data) and 2) the cylindrical model of Ruff. The model is found to be more accurate in estimating both body surface area and body volume/mass than the cylindrical model, but it is more accurate in estimating body surface area than it is for estimating body volume/mass (as reflected by the standard error of the estimate when "independently estimated" surface area or volume/mass is regressed on estimates derived from the present model). Two practical applications of the model are tested. In the first test, the relative contribution of the limbs versus the trunk to the body's volume and surface area is compared between "heat-adapted" and "cold-adapted" populations. As expected, the "cold-adapted" group has significantly more of its body surface area and volume in its trunk than does the "heat-adapted" group. In the second test, we evaluate the effect of variation in bi-iliac breadth, elongated or foreshortened limbs, and differences in crural index on the body's surface area to volume ratio (SA:V). Results indicate that the effects of bi-iliac breadth on SA:V are substantial, while those of limb lengths and (especially) the crural index are minor, which suggests that factors other than surface area relative to volume are driving morphological variation and ecogeographical patterning in limb prorportions. © 2014 Wiley Periodicals, Inc.

Analysis of the sorption properties of different soils using water vapour adsorption and potentiometric titration methods

NASA Astrophysics Data System (ADS)

Skic, Kamil; Boguta, Patrycja; Sokołowska, Zofia

2016-07-01

Parameters of specific surface area as well as surface charge were used to determine and compare sorption properties of soils with different physicochemical characteristics. The gravimetric method was used to obtain water vapour isotherms and then specific surface areas, whereas surface charge was estimated from potentiometric titration curves. The specific surface area varied from 12.55 to 132.69 m2 g-1 for Haplic Cambisol and Mollic Gleysol soil, respectively, and generally decreased with pH (R=0.835; α = 0.05) and when bulk density (R=-0.736; α = 0.05) as well as ash content (R=-0.751; α = 0.05) increased. In the case of surface charge, the values ranged from 63.00 to 844.67 μmol g-1 Haplic Fluvisol and Mollic Gleysol, respecively. Organic matter gave significant contributions to the specific surface area and cation exchange capacity due to the large surface area and numerous surface functional groups, containing adsorption sites for water vapour molecules and for ions. The values of cation exchange capacity and specific surface area correlated linearly at the level of R=0.985; α = 0.05.

Electrodeposition of Highly Porous Pt Nanoparticles Studied by Quantitative 3D Electron Tomography: Influence of Growth Mechanisms and Potential Cycling on the Active Surface Area.

PubMed

Ustarroz, Jon; Geboes, Bart; Vanrompay, Hans; Sentosun, Kadir; Bals, Sara; Breugelmans, Tom; Hubin, Annick

2017-05-17

Nanoporous Pt nanoparticles (NPs) are promising fuel cell catalysts due to their large surface area and increased electrocatalytic activity toward the oxygen reduction reaction (ORR). Herein, we report on the influence of the growth mechanisms on the surface properties of electrodeposited Pt dendritic NPs with large surface areas. The electrochemically active surface was studied by hydrogen underpotential deposition (H UPD) and compared for the first time to high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) quantitative 3D electron tomography of individual nanoparticles. Large nucleation overpotential leads to a large surface coverage of roughened spheroids, which provide a large roughness factor (R f ) but low mass-specific electrochemically active surface area (EASA). Lowering the nucleation overpotential leads to highly porous Pt NPs with pores stretching to the center of the structure. At the expense of smaller R f , the obtained EASA values of these structures are in the range of those of large surface area supported fuel cell catalysts. The active surface area of the Pt dendritic NPs was measured by electron tomography, and it was found that the potential cycling in the H adsorption/desorption and Pt oxidation/reduction region, which is generally performed to determine the EASA, leads to a significant reduction of that surface area due to a partial collapse of their dendritic and porous morphology. Interestingly, the extrapolation of the microscopic tomography results in macroscopic electrochemical parameters indicates that the surface properties measured by H UPD are comparable to the values measured on individual NPs by electron tomography after the degradation caused by the H UPD measurement. These results highlight that the combination of electrochemical and quantitative 3D surface analysis techniques is essential to provide insights into the surface properties, the electrochemical stability, and, hence, the applicability of these materials. Moreover, it indicates that care must be taken with widely used electrochemical methods of surface area determination, especially in the case of large surface area and possibly unstable nanostructures, since the measured surface can be strongly affected by the measurement itself.

Surface premelting/recrystallization governing the collapse of open-cell nanoporous Cu via thermal annealing.

PubMed

Wang, L; Zhang, X M; Deng, L; Tang, J F; Xiao, S F; Deng, H Q; Hu, W Y

2018-06-04

We systematically investigate the collapse of a set of open-cell nanoporous Cu (np-Cu) materials with the same porosity and shape but different specific surface areas, during thermal annealing, by performing large-scale molecular dynamics simulations. Two mechanisms govern the collapse of np-Cu. One is direct surface premelting, facilitating the collapse of np-Cu, when the specific surface area is less than a critical value (∼2.38 nm-1). The other is recrystallization followed by surface premelting, accelerating the sloughing of ligaments and the annihilation of voids, when the critical specific surface area is exceeded. Surface premelting results from surface reconstruction by prompting localized "disordering" and "chaos" on the surface, and the melting temperature reduces linearly with the increase of the specific surface area. Recrystallization is followed by surface premelting as the melting temperature is below the supercooling point, where a liquid is unstable and instantaneously recrystallizes.

Progressive alterations of the auditory association areas in young non-psychotic offspring of schizophrenia patients.

PubMed

Bhojraj, Tejas S; Sweeney, John A; Prasad, Konasale M; Eack, Shaun; Rajarethinam, Rajaprabhakaran; Francis, Alan N; Montrose, Debra M; Keshavan, Matcheri S

2011-02-01

Schizophrenia may involve progressive alterations of structure and hemispheric lateralization of auditory association areas (AAA) within the superior temporal gyrus. These alterations may be greater in male patients. It is unclear if these deficits are state-dependent or whether they predate illness onset and reflect familial diathesis. We sought to compare AAA cortical thickness, surface area and lateralization across adolescent and young adult non-psychotic offspring of schizophrenia patients (OS) and healthy controls at baseline and one year follow-up. We also assessed the moderating effect of gender on these measures. Fifty-six OS and thirty-six control subjects were assessed at baseline and at follow-up on AAA surface area and thickness using FreeSurfer to process T1-MRI-images. We used repeated measures ANCOVAs, controlling intra cranial volume and age with assessment-time and side as within-subject factors and gender and study group as between-subject factors. Surface area deficit in OS was greater on the left than on the right, as reflected in a lower surface area laterality-index (left-right/left + right × 100) in OS compared to controls. Left, but not right surface area and surface area laterality-index showed a longitudinal decline in OS compared to controls. Male OS declined more than controls on surface area and thickness. Left AAA surface area may progressively decline in young non-psychotic offspring at familial diathesis for schizophrenia causing a continuing reversal of the leftward AAA lateralization. Progressive surface area reduction and thinning of AAA may be more prominent in young non-psychotic male offspring at risk for schizophrenia. Copyright © 2010 Elsevier Ltd. All rights reserved.

Parallel, stochastic measurement of molecular surface area.

PubMed

Juba, Derek; Varshney, Amitabh

2008-08-01

Biochemists often wish to compute surface areas of proteins. A variety of algorithms have been developed for this task, but they are designed for traditional single-processor architectures. The current trend in computer hardware is towards increasingly parallel architectures for which these algorithms are not well suited. We describe a parallel, stochastic algorithm for molecular surface area computation that maps well to the emerging multi-core architectures. Our algorithm is also progressive, providing a rough estimate of surface area immediately and refining this estimate as time goes on. Furthermore, the algorithm generates points on the molecular surface which can be used for point-based rendering. We demonstrate a GPU implementation of our algorithm and show that it compares favorably with several existing molecular surface computation programs, giving fast estimates of the molecular surface area with good accuracy.

Surface-area-controlled synthesis of porous TiO2 thin films for gas-sensing applications

NASA Astrophysics Data System (ADS)

Park, Jae Young; Kim, Ho-hyoung; Rana, Dolly; Jamwal, Deepika; Katoch, Akash

2017-03-01

Surface-area-controlled porous TiO2 thin films were prepared via a simple sol-gel chemical route, and their gas-sensing properties were thoroughly investigated in the presence of typical oxidizing NO2 gas. The surface area of TiO2 thin films was controlled by developing porous TiO2 networked by means of controlling the TiO2-to-TTIP (titanium isopropoxide, C12H28O4Ti) molar ratio, where TiO2 nanoparticles of size ˜20 nm were used. The sensor’s response was found to depend on the surface area of the TiO2 thin films. The porous TiO2 thin-film sensor with greater surface area was more sensitive than those of TiO2 thin films with lesser surface area. The improved sensing ability was ascribed to the porous network formed within the thin films by TiO2 sol. Our results show that surface area is a key parameter for obtaining superior gas-sensing performance; this provides important guidelines for preparing and using porous thin films for gas-sensing applications.

The effects of green areas on air surface temperature of the Kuala Lumpur city using WRF-ARW modelling and Remote Sensing technique

NASA Astrophysics Data System (ADS)

Isa, N. A.; Mohd, W. M. N. Wan; Salleh, S. A.; Ooi, M. C. G.

2018-02-01

Matured trees contain high concentration of chlorophyll that encourages the process of photosynthesis. This process produces oxygen as a by-product and releases it into the atmosphere and helps in lowering the ambient temperature. This study attempts to analyse the effect of green area on air surface temperature of the Kuala Lumpur city. The air surface temperatures of two different dates which are, in March 2006 and March 2016 were simulated using the Weather Research and Forecasting (WRF) model. The green area in the city was extracted using the Normalized Difference Vegetation Index (NDVI) from two Landsat satellite images. The relationship between the air surface temperature and the green area were analysed using linear regression models. From the study, it was found that, the green area was significantly affecting the distribution of air temperature within the city. A strong negative correlation was identified through this study which indicated that higher NDVI values tend to have lower air surface temperature distribution within the focus study area. It was also found that, different urban setting in mixed built-up and vegetated areas resulted in different distributions of air surface temperature. Future studies should focus on analysing the air surface temperature within the area of mixed built-up and vegetated area.

30 CFR 761.11 - Areas where surface coal mining operations are prohibited or limited.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Areas where surface coal mining operations are....11 Areas where surface coal mining operations are prohibited or limited. You may not conduct surface coal mining operations on the following lands unless you either have valid existing rights, as...

30 CFR 761.11 - Areas where surface coal mining operations are prohibited or limited.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas where surface coal mining operations are....11 Areas where surface coal mining operations are prohibited or limited. You may not conduct surface coal mining operations on the following lands unless you either have valid existing rights, as...

30 CFR 761.11 - Areas where surface coal mining operations are prohibited or limited.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Areas where surface coal mining operations are....11 Areas where surface coal mining operations are prohibited or limited. You may not conduct surface coal mining operations on the following lands unless you either have valid existing rights, as...

Flush mounting of thin film sensors

NASA Technical Reports Server (NTRS)

Moore, Thomas C., Sr. (Inventor)

1992-01-01

Flush mounting of a sensor on a surface is provided by first forming a recessed area on the surface. Next, an adhesive bonding mixture is introduced into the recessed area. The adhesive bonding mixture is chosen to provide thermal expansion matching with the surface surrounding the recessed area. A strip of high performance polymeric tape is provided, with the sensor attached to the underside thereof, and the tape is positioned over the recessed area so that it acts as a carrier of the sensor. A shim having flexibility so that it will conform to the surface surrounding the recessed area is placed over the tape, and a vacuum pad is placed over the shim. The area above the surface is then evacuated while holding the sensor flush with the surface during curing of the adhesive bonding mixture. After such curing, the pad, shim, and tape are removed from the sensor, electrical connections for the sensor are provided, after which the remaining space in the recessed area is filled with a polymeric foam.

BET surface area distributions in polar stream sediments: Implications for silicate weathering in a cold-arid environment

USGS Publications Warehouse

Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L

2014-01-01

BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 μm) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.

30 CFR 717.14 - Backfilling and grading of road cuts, mine entry area cuts, and other surface work areas.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Backfilling and grading of road cuts, mine entry area cuts, and other surface work areas. 717.14 Section 717.14 Mineral Resources OFFICE OF SURFACE... MINING GENERAL PERFORMANCE STANDARDS § 717.14 Backfilling and grading of road cuts, mine entry area cuts...

Impact of Exposure to Pressure of 50 MPa on the Specific Surface Area of Clay

NASA Astrophysics Data System (ADS)

Koszela-Marek, Ewa

2017-12-01

The paper presents results of laboratory tests conducted to determine the impact of pressure of 50 MPa on specific surface area of clay. These tests were carried out in an original, high-pressure test stand. The specific surface area of clay extracted directly from an open pit mine was compared with the specific surface area of the same clay subjected to the pressure of 50 MPa in a high-pressure chamber. The study found that the specific surface area of the clay subjected to the pressure of 50 MPa increased distinctly by over 35 %. The increase in specific surface can be a result of changes in the microstructure of clay particles and microstructural alteration in the soil skeleton, caused by the pressure.

The Use of CASES-97 Observations to Assess and Parameterize the Impact of Land-Surface Heterogeneity on Area-Average Surface Heat Fluxes for Large-Scale Coupled Atmosphere-Hydrology Models

NASA Technical Reports Server (NTRS)

Chen, Fei; Yates, David; LeMone, Margaret

2001-01-01

To understand the effects of land-surface heterogeneity and the interactions between the land-surface and the planetary boundary layer at different scales, we develop a multiscale data set. This data set, based on the Cooperative Atmosphere-Surface Exchange Study (CASES97) observations, includes atmospheric, surface, and sub-surface observations obtained from a dense observation network covering a large region on the order of 100 km. We use this data set to drive three land-surface models (LSMs) to generate multi-scale (with three resolutions of 1, 5, and 10 kilometers) gridded surface heat flux maps for the CASES area. Upon validating these flux maps with measurements from surface station and aircraft, we utilize them to investigate several approaches for estimating the area-integrated surface heat flux for the CASES97 domain of 71x74 square kilometers, which is crucial for land surface model development/validation and area water and energy budget studies. This research is aimed at understanding the relative contribution of random turbulence versus organized mesoscale circulations to the area-integrated surface flux at the scale of 100 kilometers, and identifying the most important effective parameters for characterizing the subgrid-scale variability for large-scale atmosphere-hydrology models.

Diagnostic accuracy of stress perfusion CMR in comparison with quantitative coronary angiography: fully quantitative, semiquantitative, and qualitative assessment.

PubMed

Mordini, Federico E; Haddad, Tariq; Hsu, Li-Yueh; Kellman, Peter; Lowrey, Tracy B; Aletras, Anthony H; Bandettini, W Patricia; Arai, Andrew E

2014-01-01

This study's primary objective was to determine the sensitivity, specificity, and accuracy of fully quantitative stress perfusion cardiac magnetic resonance (CMR) versus a reference standard of quantitative coronary angiography. We hypothesized that fully quantitative analysis of stress perfusion CMR would have high diagnostic accuracy for identifying significant coronary artery stenosis and exceed the accuracy of semiquantitative measures of perfusion and qualitative interpretation. Relatively few studies apply fully quantitative CMR perfusion measures to patients with coronary disease and comparisons to semiquantitative and qualitative methods are limited. Dual bolus dipyridamole stress perfusion CMR exams were performed in 67 patients with clinical indications for assessment of myocardial ischemia. Stress perfusion images alone were analyzed with a fully quantitative perfusion (QP) method and 3 semiquantitative methods including contrast enhancement ratio, upslope index, and upslope integral. Comprehensive exams (cine imaging, stress/rest perfusion, late gadolinium enhancement) were analyzed qualitatively with 2 methods including the Duke algorithm and standard clinical interpretation. A 70% or greater stenosis by quantitative coronary angiography was considered abnormal. The optimum diagnostic threshold for QP determined by receiver-operating characteristic curve occurred when endocardial flow decreased to <50% of mean epicardial flow, which yielded a sensitivity of 87% and specificity of 93%. The area under the curve for QP was 92%, which was superior to semiquantitative methods: contrast enhancement ratio: 78%; upslope index: 82%; and upslope integral: 75% (p = 0.011, p = 0.019, p = 0.004 vs. QP, respectively). Area under the curve for QP was also superior to qualitative methods: Duke algorithm: 70%; and clinical interpretation: 78% (p < 0.001 and p < 0.001 vs. QP, respectively). Fully quantitative stress perfusion CMR has high diagnostic accuracy for detecting obstructive coronary artery disease. QP outperforms semiquantitative measures of perfusion and qualitative methods that incorporate a combination of cine, perfusion, and late gadolinium enhancement imaging. These findings suggest a potential clinical role for quantitative stress perfusion CMR. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Atrial Septopulmonary Bundle of the Posterior Left Atrium Provides a Substrate for Atrial Fibrillation Initiation in a Model of Vagally Mediated Pulmonary Vein Tachycardia of the Structurally Normal Heart

PubMed Central

Klos, Matthew; Calvo, David; Yamazaki, Masatoshi; Zlochiver, Sharon; Mironov, Sergey; Cabrera, José-Angel; Sanchez-Quintana, Damian; Jalife, José; Berenfeld, Omer; Kalifa, Jérôme

2009-01-01

Background The posterior left atrium (PLA) and pulmonary veins (PVs) have been shown to be critical for atrial fibrillation (AF) initiation. However, the detailed mechanisms of reentry and AF initiation by PV impulses are poorly understood. We hypothesized that PV impulses trigger reentry and AF by undergoing wavebreaks as a result of sink-to-source mismatch at specific PV-PLA transitions along the septopulmonary bundle, where there are changes in thickness and fiber direction. Methods and Results In 7 Langendorff-perfused sheep hearts AF was initiated by a burst of 6 pulses (CL 80 to 150ms) delivered to the left inferior or right superior PV ostium 100 to 150 ms after the sinus impulse in the presence of 0.5 μmol/L acetylcholine. The exposed septal-PLA endocardial area was mapped with high spatio-temporal resolution (DI-4-ANEPPS, 1000-fr/s) during AF initiation. Isochronal maps for each paced beat preceding AF onset were constructed to localize areas of conduction delay and block. Phase movies allowed the determination of the wavebreak sites at the onset of AF. Thereafter, the PLA myocardial wall thickness was quantified by echocardiography, and the fiber direction in the optical field of view was determined after peeling off the endocardium. Finally, isochrone, phase and conduction velocity maps were superimposed on the corresponding anatomic pictures for each of the 28 episodes of AF initiation. The longest delays of the paced PV impulses, as well as the first wavebreak, occurred at those boundaries along the septopulmonary bundle that showed sharp changes in fiber direction and the largest and most abrupt increase in myocardial thickness. Conclusion Waves propagating from the PVs into the PLA originating from a simulated PV tachycardia triggered reentry and vagally mediated AF by breaking at boundaries along the septopulmonary bundle where abrupt changes in thickness and fiber direction resulted in sink-to-source mismatch and low safety for propagation. PMID:19609369

An integrated coronary circulation teaching model.

PubMed

van Oostrom, Johannes H; Kentgens, S; Beneken, J E W; Gravenstein, J S

2006-08-01

We present in this paper a model of the coronary circulation. This model is integrated with a model of the systemic circulation, and contains models for oxygen supply and demand. Three compartments are created: one for the right ventricle, one for the epicardial segment of the left ventricle and one for the endo-cardial segment of the left ventricle. The model was implemented in the Java programming language and contains a visual representation of the left and right ventricles which beat in real time. Color shading is used to represent the partial pressure of oxygen in the segments. A multitude of model parameters can be changed to simulate different scenarios. The output of the model was characterized under different conditions and the results verified by clinicians. Educational models of human physiology can be very useful for a more in depth understanding of complete physiologic systems. The models must however have enough complexity, interaction with other systems, and realism to show the concepts being taught.

Investigating the Flow and Biomechanics of the Embryonic Zebrafish Heart

NASA Astrophysics Data System (ADS)

Johnson, Brennan; Garrity, Deborah; Dasi, Lakshmi

2010-11-01

Understanding flow and kinematic characteristics of the embryonic heart is a prerequisite to devise early intervention or detection methods in the context of congenital heart defects. In this study, the kinematics and fluid dynamics of the embryonic zebrafish heart were analyzed through the early stages of cardiac development (24-48 hours post-fertilization) in vivo using optical microscopy and high-speed video. Endocardial walls and individual blood cells were segmented from raw images and were tracked through the cardiac cycle. Particle tracking velocimetry analysis yielded quantitative blood cell velocity field, chamber volume, and flow rate information. It was seen that the pumping mechanism starts as a combined peristaltic and suction pump while the heart is in the tube configuration and transforms into a positive displacement pump after cardiac looping. Strong two-phase nature of the fluid is evident. This work provides us new understanding of the spatio-temporal characteristics of kinematics and blood cell velocity field inside the developing heart.

Surgical ablation of ventricular tachycardia secondary to congenital ventricular septal aneurysm.

PubMed

Graffigna, A; Minzioni, G; Ressia, L; Vigano, M

1994-04-01

Three patients underwent surgical ablation for ventricular tachycardia resulting from an aneurysm of the membranous portion of the ventricular septum. Two patients had a definite history of cardiac murmur during infancy, and one of them was found at the time of operation to have a left-to-right shunt through the apex of the aneurysm. The earliest ventricular activation sites were located around the neck of the aneurysm and were ablated in 1 patient by encircling the endocardial ventriculotomy and by cryoablation in the remaining 2. After focus resection had been completed, aneurysm resection and ventricular septal reconstruction were performed. All patients were alive and free of ventricular tachycardia and did not need medication as of 61, 66, and 88 months postoperatively. Spontaneous closure of a ventricular septal defect may lead to the formation of an aneurysm in the ventricular septum that may sustain ventricular tachycardias. Such arrhythmias can be effectively treated using electrically guided surgical techniques.

Vibration-synchronized magnetic resonance imaging for the detection of myocardial elasticity changes.

PubMed

Elgeti, Thomas; Tzschätzsch, Heiko; Hirsch, Sebastian; Krefting, Dagmar; Klatt, Dieter; Niendorf, Thoralf; Braun, Jürgen; Sack, Ingolf

2012-04-01

Vibration synchronized magnetic resonance imaging of harmonically oscillating tissue interfaces is proposed for cardiac magnetic resonance elastography. The new approach exploits cardiac triggered cine imaging synchronized with extrinsic harmonic stimulation (f = 22.83 Hz) to display oscillatory tissue deformations in magnitude images. Oscillations are analyzed by intensity threshold-based image processing to track wave amplitude variations over the cardiac cycle. In agreement to literature data, results in 10 volunteers showed that endocardial wave amplitudes during systole (0.13 ± 0.07 mm) were significantly lower than during diastole (0.34 ± 0.14 mm, P < 0.001). Wave amplitudes were found to decrease 117 ± 40 ms before myocardial contraction and to increase 75 ± 31 ms before myocardial relaxation. Vibration synchronized magnetic resonance imaging improves the temporal resolution of magnetic resonance elastography as it overcomes the use of extra motion encoding gradients, is less sensitive to susceptibility artifacts, and does not suffer from dynamic range constraints frequently encountered in phase-based magnetic resonance elastography. Copyright © 2012 Wiley Periodicals, Inc.

[Successful repair of total anomalous pulmonary venous connection and incomplete endocardial cushion defect associated with left isomerism].

PubMed

Mizuno, A; Nakamura, Y; Takayasu, H; Saitoh, H

1993-05-01

Successful repair of a 8-month-old girl with polysplenia was reported. The cardiovascular anomalies were TAPVC (II b), incomplete ECD, interruption of inferior vena cava with hemiazygos continuation, bilateral superior vena cava, and left superior vena cava draining into the coronary sinus. Cardiopulmonary bypass was established with ascending aortic perfusion and caval cannulation. A left superior vena cava was directly cannulated after establishing partial bypass. In this case the left pulmonary vein drained into the right atrium near the orifice of the coronary sinus, so the atrial septal flap was made and sutured between the orifice of the left pulmonary vein and the coronary sinus in order to avoid late pulmonary vein obstruction. Then, atrium was separated by an intraatrial baffle which was sutured to the atrial septal flap. Recently, it becomes possible to surgical repair of polysplenia syndrome according to the advancements of the diagnostic methods, cardiopulmonary bypass, and the technique of the open heart surgery.

Leadless cardiac pacemakers: present and the future.

PubMed

Chew, Derek S; Kuriachan, Vikas

2018-01-01

Pacing technology for many decades has been composed of a generator attached to leads that are usually transvenous. Recently, leadless pacemakers have been studied in clinical settings and now available for use in many countries. This includes the single-component Nanostim Leadless Cardiac Pacemaker and Micra Transcatheter Pacing System, as well as the multicomponent Wireless Stimulation Endocardial system. Clinical studies in single-component leadless pacing technology has shown that they can be successfully implanted with minimal complications. The follow-up studies also seem to confirm the findings from the initial clinical trials. These systems offer some advantages over a traditional pacing system comprised of a subcutaneous generator and transvenous leads. In many ways, these leadless systems are disruptive technologies that are changing the traditional pacemaker concept and preferred for some patients. Ongoing research is needed to better assess their long-term function, safety, and end-of-life strategies. In the future, multichamber leadless pacing is expected to be developed and perhaps obviating the need for transvenous leads and their associated complications.

Uncontrolled angiogenic precursor expansion causes coronary artery anomalies in mice lacking Pofut1.

PubMed

Wang, Yidong; Wu, Bingruo; Lu, Pengfei; Zhang, Donghong; Wu, Brian; Varshney, Shweta; Del Monte-Nieto, Gonzalo; Zhuang, Zhenwu; Charafeddine, Rabab; Kramer, Adam H; Sibinga, Nicolas E; Frangogiannis, Nikolaos G; Kitsis, Richard N; Adams, Ralf H; Alitalo, Kari; Sharp, David J; Harvey, Richard P; Stanley, Pamela; Zhou, Bin

2017-09-18

Coronary artery anomalies may cause life-threatening cardiac complications; however, developmental mechanisms underpinning coronary artery formation remain ill-defined. Here we identify an angiogenic cell population for coronary artery formation in mice. Regulated by a DLL4/NOTCH1/VEGFA/VEGFR2 signaling axis, these angiogenic cells generate mature coronary arteries. The NOTCH modulator POFUT1 critically regulates this signaling axis. POFUT1 inactivation disrupts signaling events and results in excessive angiogenic cell proliferation and plexus formation, leading to anomalous coronary arteries, myocardial infarction and heart failure. Simultaneous VEGFR2 inactivation fully rescues these defects. These findings show that dysregulated angiogenic precursors link coronary anomalies to ischemic heart disease.Though coronary arteries are crucial for heart function, the mechanisms guiding their formation are largely unknown. Here, Wang et al. identify a unique, endocardially-derived angiogenic precursor cell population for coronary artery formation in mice and show that a DLL4/NOTCH1/VEGFA/VEGFR2 signaling axis is key for coronary artery development.

Rationale of cerebral protection devices in left atrial appendage occlusion.

PubMed

Meincke, Felix; Spangenberg, Tobias; Kreidel, Felix; Frerker, Christian; Virmani, Renu; Ladich, Elena; Kuck, Karl-Heinz; Ghanem, Alexander

2017-01-01

Aims of this case-series were to assess the feasibility of cerebral protection devices in interventional left atrial appendage occlusion (iLAAO) procedures and to yield insight into the pathomorphological correlate of early, procedural cerebral embolization during iLAAO. Five consecutive patients underwent iLLO flanked by the Sentinel CPS® (Claret Medical, Inc., Santa Rosa, CA) cerebral protection system. Placement and recapture of the Sentinel ® device as well as the iLAAO were successful and safe in all cases. Histomorphometric analysis of the collected filters showed embolized debris in all patients. Acute thrombus was found in three patients, organizing thrombus in four. Interestingly, two patients had endocardial or myocardial tissue in their filters. Cerebral protection during iLAAO with the Sentinel CPS ® device is feasible. Furthermore, this dataset identifies the formation and embolization of thrombus and cardiac tissue as emboligeneic sources and potential future targets to reduce procedural complications. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Principal curvatures and area ratio of propagating surfaces in isotropic turbulence

NASA Astrophysics Data System (ADS)

Zheng, Tianhang; You, Jiaping; Yang, Yue

2017-10-01

We study the statistics of principal curvatures and the surface area ratio of propagating surfaces with a constant or nonconstant propagating velocity in isotropic turbulence using direct numerical simulation. Propagating surface elements initially constitute a plane to model a planar premixed flame front. When the statistics of evolving propagating surfaces reach the stationary stage, the statistical profiles of principal curvatures scaled by the Kolmogorov length scale versus the constant displacement speed scaled by the Kolmogorov velocity scale collapse at different Reynolds numbers. The magnitude of averaged principal curvatures and the number of surviving surface elements without cusp formation decrease with increasing displacement speed. In addition, the effect of surface stretch on the nonconstant displacement speed inhibits the cusp formation on surface elements at negative Markstein numbers. In order to characterize the wrinkling process of the global propagating surface, we develop a model to demonstrate that the increase of the surface area ratio is primarily due to positive Lagrangian time integrations of the area-weighted averaged tangential strain-rate term and propagation-curvature term. The difference between the negative averaged mean curvature and the positive area-weighted averaged mean curvature characterizes the cellular geometry of the global propagating surface.

30 CFR 717.15 - Disposal of excess rock and earth materials on surface areas.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Disposal of excess rock and earth materials on surface areas. 717.15 Section 717.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS § 717.15 Disposal of excess rock and earth materials on surface areas. Excess rock and earth...

30 CFR 717.15 - Disposal of excess rock and earth materials on surface areas.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Disposal of excess rock and earth materials on surface areas. 717.15 Section 717.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS § 717.15 Disposal of excess rock and earth materials on surface areas. Excess rock and earth...

30 CFR 717.15 - Disposal of excess rock and earth materials on surface areas.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Disposal of excess rock and earth materials on surface areas. 717.15 Section 717.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS § 717.15 Disposal of excess rock and earth materials on surface areas. Excess rock and earth...

30 CFR 717.15 - Disposal of excess rock and earth materials on surface areas.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Disposal of excess rock and earth materials on surface areas. 717.15 Section 717.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS § 717.15 Disposal of excess rock and earth materials on surface areas. Excess rock and earth...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2011 CFR

2011-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2014 CFR

2014-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2010 CFR

2010-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2012 CFR

2012-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

Quantitative X-ray computed tomography peritoneography in malignant peritoneal mesothelioma patients receiving intraperitoneal chemotherapy.

PubMed

Leinwand, Joshua C; Zhao, Binsheng; Guo, Xiaotao; Krishnamoorthy, Saravanan; Qi, Jing; Graziano, Joseph H; Slavkovic, Vesna N; Bates, Gleneara E; Lewin, Sharyn N; Allendorf, John D; Chabot, John A; Schwartz, Lawrence H; Taub, Robert N

2013-12-01

Intraperitoneal chemotherapy is used to treat peritoneal surface-spreading malignancies. We sought to determine whether volume and surface area of the intraperitoneal chemotherapy compartments are associated with overall survival and posttreatment glomerular filtration rate (GFR) in malignant peritoneal mesothelioma (MPM) patients. Thirty-eight MPM patients underwent X-ray computed tomography peritoneograms during outpatient intraperitoneal chemotherapy. We calculated volume and surface area of contrast-filled compartments by semiautomated computer algorithm. We tested whether these were associated with overall survival and posttreatment GFR. Decreased likelihood of mortality was associated with larger surface areas (p = 0.0201) and smaller contrast-filled compartment volumes (p = 0.0341), controlling for age, sex, histologic subtype, and presence of residual disease >0.5 cm postoperatively. Larger volumes were associated with higher posttreatment GFR, controlling for pretreatment GFR, body surface area, surface area, and the interaction between body surface area and volume (p = 0.0167). Computed tomography peritoneography is an appropriate modality to assess for maldistribution of intraperitoneal chemotherapy. In addition to identifying catheter failure and frank loculation, quantitative analysis of the contrast-filled compartment's surface area and volume may predict overall survival and cisplatin-induced nephrotoxicity. Prospective studies should be undertaken to confirm and extend these findings to other diseases, including advanced ovarian carcinoma.

Target surface area effects on hot electron dynamics from high intensity laser–plasma interactions

DOE PAGES

Zulick, C.; Raymond, A.; McKelvey, A.; ...

2016-06-15

Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron sheath field confinement on electron dynamics. X-ray emission due to energetic electrons was imaged using a K α imaging crystal. Electrons were observed to travel along the surface of wire targets, and were slowed mainly by the induced fields. Targets with reduced surface areas were correlated with increased hot electron densities and proton energies. Furthermore, Hybrid Vlasov–Fokker–Planck simulations demonstrated increased electric sheath field strength in reduced surface area targets.

Darkening effect on AZ31B magnesium alloy surface induced by nanosecond pulse Nd:YAG laser

NASA Astrophysics Data System (ADS)

Guan, Y. C.; Zhou, W.; Zheng, H. Y.; Li, Z. L.

2013-09-01

Permanent darkening effect was achieved on surface of AZ31B Mg alloy irradiated with nanosecond pulse Nd:YAG laser, and special attention was made to examine how surface structure as well as oxidation affect the darkening effect. Experiments were carried out to characterize morphological evolution and chemical composition of the irradiated areas by optical reflection spectrometer, Talysurf surface profiler, SEM, EDS, and XPS. The darkening effect was found to be occurred at the surface under high laser energy. Optical spectra showed that the induced darkening surface was uniform over the spectral range from 200 nm to 1100 nm. SEM and surface profiler showed that surface morphology of darkening areas consisted of large number of micron scale cauliflower-like clusters and protruding particles. EDS and XPS showed that compared to non-irradiated area, oxygen content at the darkening areas increased significantly. It was proposed a mechanism that involved trapping of light in the surface morphology and chemistry variation of irradiated areas to explain the laser-induced darkening effect on AZ31B Mg alloy.

Brain cortical characteristics of lifetime cognitive ageing.

PubMed

Cox, Simon R; Bastin, Mark E; Ritchie, Stuart J; Dickie, David Alexander; Liewald, Dave C; Muñoz Maniega, Susana; Redmond, Paul; Royle, Natalie A; Pattie, Alison; Valdés Hernández, Maria; Corley, Janie; Aribisala, Benjamin S; McIntosh, Andrew M; Wardlaw, Joanna M; Deary, Ian J

2018-01-01

Regional cortical brain volume is the product of surface area and thickness. These measures exhibit partially distinct trajectories of change across the brain's cortex in older age, but it is unclear which cortical characteristics at which loci are sensitive to cognitive ageing differences. We examine associations between change in intelligence from age 11 to 73 years and regional cortical volume, surface area, and thickness measured at age 73 years in 568 community-dwelling older adults, all born in 1936. A relative positive change in intelligence from 11 to 73 was associated with larger volume and surface area in selective frontal, temporal, parietal, and occipital regions (r < 0.180, FDR-corrected q < 0.05). There were no significant associations between cognitive ageing and a thinner cortex for any region. Interestingly, thickness and surface area were phenotypically independent across bilateral lateral temporal loci, whose surface area was significantly related to change in intelligence. These findings suggest that associations between regional cortical volume and cognitive ageing differences are predominantly driven by surface area rather than thickness among healthy older adults. Regional brain surface area has been relatively underexplored, and is a potentially informative biomarker for identifying determinants of cognitive ageing differences.

Pulmonary diffusional screening and the scaling laws of mammalian metabolic rates

NASA Astrophysics Data System (ADS)

Hou, Chen; Mayo, Michael

2011-12-01

Theoretical considerations suggest that the mammalian metabolic rate is linearly proportional to the surface areas of mitochondria, capillary, and alveolar membranes. However, the scaling exponents of these surface areas to the mammals' body mass (approximately 0.9-1) are higher than exponents of the resting metabolic rate (RMR) to body mass (approximately 0.75), although similar to the one of exercise metabolic rate (EMR); the underlying physiological cause of this mismatch remains unclear. The analysis presented here shows that discrepancies between the scaling exponents of RMR and the relevant surface areas may originate from, at least for the system of alveolar membranes in mammalian lungs, the facts that (i) not all of the surface area is involved in the gas exchange and (ii) that larger mammals host a smaller effective surface area that participates in the material exchange rate. A result of these facts is that lung surface areas unused at rest are activated under heavy breathing conditions (e.g., exercise), wherein larger mammals support larger activated surface areas that provide a higher capability to increase the gas-exchange rate, allowing for mammals to meet, for example, the high energetic demands of foraging and predation.

Determining eyeball surface area directly exposed to the effects of external factors.

PubMed

Juliszewski, Tadeusz; Kadłuczka, Filip; Kiełbasa, Paweł

2016-01-01

This article discusses determining the surface area of eyeballs of men and women exposed to the direct effects of external factors in the working environment. For one eye, the mean surface is 172-182 mm(2). The determined surface area can be used in formulas for calculating the exposure of eyeballs to harmful chemical substances in workplace air.

33 CFR 334.360 - Chesapeake Bay off Fort Monroe, Virginia; restricted area, U.S. Naval Base and Naval Surface...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., Virginia; restricted area, U.S. Naval Base and Naval Surface Weapon Center. 334.360 Section 334.360....S. Naval Base and Naval Surface Weapon Center. (a) The area. Beginning at latitude 37°01′03... Manager, Naval Surface Warfare Center, Dahlgren Division Coastal Systems Station Detachment, Fort Monroe...

33 CFR 334.360 - Chesapeake Bay off Fort Monroe, Virginia; restricted area, U.S. Naval Base and Naval Surface...

Code of Federal Regulations, 2011 CFR

2011-07-01

..., Virginia; restricted area, U.S. Naval Base and Naval Surface Weapon Center. 334.360 Section 334.360....S. Naval Base and Naval Surface Weapon Center. (a) The area. Beginning at latitude 37°01′03... Manager, Naval Surface Warfare Center, Dahlgren Division Coastal Systems Station Detachment, Fort Monroe...

In vitro effects of cisplatin-functionalized silica nanoparticles on chondrocytes

NASA Astrophysics Data System (ADS)

Bhowmick, Tridib Kumar; Yoon, Diana; Patel, Minal; Fisher, John; Ehrman, Sheryl

2010-10-01

In this study, we evaluated the combined effect of a known toxic molecule, cisplatin, in combination with relatively nontoxic nanoparticles, amorphous fumed silica, on chondrocyte cells. Cisplatin was attached to silica nanoparticles using aminopropyltriethoxy silane as a linker molecule, and characterized in terms of size, shape, specific surface area, as well as the dissolution of cisplatin from the silica surface. The primary particle diameter of the as-received silica nanoparticles ranged from 7.1 to 61 nm, estimated from measurements of specific surface area, and the primary particles were aggregated. The effects of cisplatin-functionalized silica particles with different specific surface areas (41, 85, 202, 237, and 297 m2/g) were compared in vitro on chondrocytes, the parenchymal cell of hyaline cartilage. The results show that adverse effects on cell function, as evidenced by reduced metabolic activity measured by the MTT assay and increased membrane permeability observed using the Live/Dead stain, can be correlated with specific surface area of the silica. Cisplatin-functionalized silica nanoparticles with the highest specific surface area incited the greatest response, which was almost equivalent to that induced by free cisplatin. This result suggests the importance of particle specific surface area in interactions between cells and surface-functionalized nanomaterials.

Hand burns surface area: A rule of thumb.

PubMed

Dargan, Dallan; Mandal, Anirban; Shokrollahi, Kayvan

2018-08-01

Rapid estimation of acute hand burns is important for communication, standardisation of assessment, rehabilitation and research. Use of an individual's own thumbprint area as a fraction of their total hand surface area was evaluated to assess potential utility in hand burn evaluation. Ten health professionals used an ink-covered dominant thumb pulp to cover the surfaces of their own non-dominant hand using the contralateral thumb. Thumbprints were assessed on the web spaces, sides of digits and dorsum and palm beyond the distal wrist crease. Hand surface area was estimated using the Banerjee and Sen method, and thumbprint ellipse area calculated to assess correlation. Mean estimated total hand surface area was 390.0cm 2 ±SD 51.5 (328.3-469.0), mean thumbprint ellipse area was 5.5cm 2 ±SD 1.3 (3.7-8.4), and mean estimated print number was 73.5±SD 11.0 (range 53.1-87.8, 95% CI 6.8). The mean observed number of thumbprints on one hand was 80.1±SD 5.9 (range 70.0-88.0, 95% CI 3.7), χ 2 =0.009. The combined mean of digital prints was 42, comprising a mean of two prints each on volar, dorsal, radial and ulnar digit surfaces, except volar middle and ring (3 prints each). Palmar prints were 15 (11-19), dorsal 15 (11-19), ulnar palm border 3, first web space 2, and second, third and fourth web spaces one each. Using the surface of the palm alone, excluding digits, as 0.5% of total body surface area, the area of one thumbprint was approximated as 1/30th of 1%. We have demonstrated how thumbprint area serves as a simple method for evaluating hand burn surface area. Copyright © 2018 Elsevier Ltd and ISBI. All rights reserved.

Relationships among particle number, surface area, and respirable mass concentrations in automotive engine manufacturing.

PubMed

Heitbrink, William A; Evans, Douglas E; Ku, Bon Ki; Maynard, Andrew D; Slavin, Thomas J; Peters, Thomas M

2009-01-01

This study investigated the relationships between particle number, surface area, and respirable mass concentration measured simultaneously in a foundry and an automotive engine machining and assembly center. Aerosol concentrations were measured throughout each plant with a condensation particle counter for number concentration, a diffusion charger for active surface area concentration, and an optical particle counter for respirable mass concentration. At selected locations, particle size distributions were characterized with the optical particle counter and an electrical low pressure impactor. Statistical analyses showed that active surface area concentration was correlated with ultrafine particle number concentration and weakly correlated with respirable mass concentration. Correlation between number and active surface area concentration was stronger during winter (R2 = 0.6 for both plants) than in the summer (R2 = 0.38 and 0.36 for the foundry and engine plant respectively). The stronger correlation in winter was attributed to use of direct-fire gas fired heaters that produced substantial numbers of ultrafine particles with a modal diameter between 0.007 and 0.023 mu m. These correlations support findings obtained through theoretical analysis. Such analysis predicts that active surface area increasingly underestimates geometric surface area with increasing particle size, particularly for particles larger than 100 nm. Thus, a stronger correlation between particle number concentration and active surface area concentration is expected in the presence of high concentrations of ultrafine particles. In general, active surface area concentration may be a concentration metric that is distinct from particle number concentration and respirable mass concentration. For future health effects or toxicological studies involving nano-materials or ultrafine aerosols, this finding needs to be considered, as exposure metrics may influence data interpretation.

Estimation of surface area concentration of workplace incidental nanoparticles based on number and mass concentrations

NASA Astrophysics Data System (ADS)

Park, J. Y.; Ramachandran, G.; Raynor, P. C.; Kim, S. W.

2011-10-01

Surface area was estimated by three different methods using number and/or mass concentrations obtained from either two or three instruments that are commonly used in the field. The estimated surface area concentrations were compared with reference surface area concentrations (SAREF) calculated from the particle size distributions obtained from a scanning mobility particle sizer and an optical particle counter (OPC). The first estimation method (SAPSD) used particle size distribution measured by a condensation particle counter (CPC) and an OPC. The second method (SAINV1) used an inversion routine based on PM1.0, PM2.5, and number concentrations to reconstruct assumed lognormal size distributions by minimizing the difference between measurements and calculated values. The third method (SAINV2) utilized a simpler inversion method that used PM1.0 and number concentrations to construct a lognormal size distribution with an assumed value of geometric standard deviation. All estimated surface area concentrations were calculated from the reconstructed size distributions. These methods were evaluated using particle measurements obtained in a restaurant, an aluminum die-casting factory, and a diesel engine laboratory. SAPSD was 0.7-1.8 times higher and SAINV1 and SAINV2 were 2.2-8 times higher than SAREF in the restaurant and diesel engine laboratory. In the die casting facility, all estimated surface area concentrations were lower than SAREF. However, the estimated surface area concentration using all three methods had qualitatively similar exposure trends and rankings to those using SAREF within a workplace. This study suggests that surface area concentration estimation based on particle size distribution (SAPSD) is a more accurate and convenient method to estimate surface area concentrations than estimation methods using inversion routines and may be feasible to use for classifying exposure groups and identifying exposure trends.

Influence of Laser Shock Texturing on W9 Steel Surface Friction Property

NASA Astrophysics Data System (ADS)

Fan, Yujie; Cui, Pengfei; Zhou, Jianzhong; Dai, Yibin; Guo, Erbin; Tang, Deye

2017-09-01

To improve surface friction property of high speed steel, micro-dent arrays on W9Mo3Cr4V surface were produced by laser shock processing. Friction test was conducted on smooth surface and texturing surface and effect of surface texturing density on friction property was studied. The results show that, under the same condition, friction coefficient of textured surface is lower than smooth surface with dent area density less than 6%, wear mass loss, width and depth of wear scar are smaller; Wear resistance of the surface is the best and the friction coefficient is the smallest when dent area density is 2.2%; Friction coefficient, wear mass loss, width and depth of wear scar increase correspondingly as density of dent area increases when dent area density is more than 2.2%. Abrasive wear and adhesive wear, oxidative wear appear in the wear process. Reasonable control of geometric parameters of surface texturing induced by laser shock processing is helpful to improve friction performance.

Location of Bare Soil Surface and Soil Line on the RED-NIR Spectral Plane

NASA Astrophysics Data System (ADS)

Koroleva, P. V.; Rukhovich, D. I.; Rukhovich, A. D.; Rukhovich, D. D.; Kulyanitsa, A. L.; Trubnikov, A. V.; Kalinina, N. V.; Simakova, M. S.

2017-12-01

Soil as a separate natural body occupies certain area with its own set of spectral characteristics within the RED-NIR spectral space. This is an ellipse-shaped area, and its semi-major axis is the soil line for a satellite image. The spectral area for a bare soil surface is neighboring to the areas of black carbon, straw, vegetating plants, and missing RED-NIR values. A reliable separation of the bare soil surface within the spectral space is possible with the technology of spectral neighborhood of soil line. The accuracy of this method is 90%. The determination of the bare soil surface using vegetation indices, both relative (NDVI), and perpendicular (PVI), is incorrect; the accuracy of these methods does not exceed 65%, and for most of the survey seasons it may be lower than 50%. The flat part of the "tasseled cap" described as the soil line, is not a synonym for the area of the bare soil surface. The bare soil surface on the RED-NIR plots occupies significantly smaller areas than the area of soil line according to Kauth and Thomas.

30 CFR 71.500 - Sanitary toilet facilities at surface work sites; installation requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... SURFACE WORK AREAS OF UNDERGROUND COAL MINES Sanitary Toilet Facilities at Surface Worksites of Surface...): Sanitary toilet facilities for surface work areas of underground mines are subject to the provisions of... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Sanitary toilet facilities at surface work...

30 CFR 71.500 - Sanitary toilet facilities at surface work sites; installation requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... SURFACE WORK AREAS OF UNDERGROUND COAL MINES Sanitary Toilet Facilities at Surface Worksites of Surface...): Sanitary toilet facilities for surface work areas of underground mines are subject to the provisions of... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Sanitary toilet facilities at surface work...

30 CFR 71.500 - Sanitary toilet facilities at surface work sites; installation requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... SURFACE WORK AREAS OF UNDERGROUND COAL MINES Sanitary Toilet Facilities at Surface Worksites of Surface...): Sanitary toilet facilities for surface work areas of underground mines are subject to the provisions of... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Sanitary toilet facilities at surface work...

30 CFR 71.500 - Sanitary toilet facilities at surface work sites; installation requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... SURFACE WORK AREAS OF UNDERGROUND COAL MINES Sanitary Toilet Facilities at Surface Worksites of Surface...): Sanitary toilet facilities for surface work areas of underground mines are subject to the provisions of... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Sanitary toilet facilities at surface work...

The effect of grain size and surface area on organic matter, lignin and carbohydrate concentration, and molecular compositions in Peru Margin sediments

USGS Publications Warehouse

Bergamaschi, B.A.; Tsamakis, E.; Keil, R.G.; Eglinton, T.I.; Montlucon, D.B.; Hedges, J.I.

1997-01-01

A C-rich sediment sample from the Peru Margin was sorted into nine hydrodynamically-determined grain size fractions to explore the effect of grain size distribution and sediment surface area on organic matter content and composition. The neutral monomeric carbohydrate composition, lignin oxidation product yields, total organic carbon, and total nitrogen contents were determined independently for each size fraction, in addition to sediment surface area and abundance of biogenic opal. The percent organic carbon and percent total nitrogen were strongly related to surface area in these sediments. In turn, the distribution of surface area closely followed mass distribution among the textural size classes, suggesting hydrodynamic controls on grain size also control organic carbon content. Nevertheless, organic compositional distinctions were observed between textural size classes. Total neutral carbohydrate yields in the Peru Margin sediments were found to closely parallel trends in total organic carbon, increasing in abundance among grain size fractions in proportion to sediment surface area. Coincident with the increases in absolute abundance, rhamnose and mannose increased as a fraction of the total carbohydrate yield in concert with surface area, indicating these monomers were preferentially represented in carbohydrates associated with surfaces. Lignin oxidation product yields varied with surface area when normalized to organic carbon, suggesting that the terrestrially-derived component may be diluted by sorption of marine derived material. Lignin-based parameters suggest a separate source for terrestrially derived material associated with sand-size material as opposed to that associated with silts and clays. Copyright ?? 1997 Elsevier Science Ltd.

The effect of grain size and surface area on organic matter, lignin and carbohydrate concentration, and molecular compositions in Peru Margin sediments

NASA Astrophysics Data System (ADS)

Bergamaschi, Brian A.; Tsamakis, Elizabeth; Keil, Richard G.; Eglinton, Timothy I.; Montluçon, Daniel B.; Hedges, John I.

1997-03-01

A C-rich sediment sample from the Peru Margin was sorted into nine hydrodynamically-determined grain size fractions to explore the effect of grain size distribution and sediment surface area on organic matter content and composition. The neutral monomeric carbohydrate composition, lignin oxidation product yields, total organic carbon, and total nitrogen contents were determined independently for each size fraction, in addition to sediment surface area and abundance of biogenic opal. The percent organic carbon and percent total nitrogen were strongly related to surface area in these sediments. In turn, the distribution of surface area closely followed mass distribution among the textural size classes, suggesting hydrodynamic controls on grain size also control organic carbon content. Nevertheless, organic compositional distinctions were observed between textural size classes. Total neutral carbohydrate yields in the Peru Margin sediments were found to closely parallel trends in total organic carbon, increasing in abundance among grain size fractions in proportion to sediment surface area. Coincident with the increases in absolute abundance, rhamnose and mannose increased as a fraction of the total carbohydrate yield in concert with surface area, indicating these monomers were preferentially represented in carbohydrates associated with surfaces. Lignin oxidation product yields varied with surface area when normalized to organic carbon, suggesting that the terrestrially-derived component may be diluted by sorption of marine derived material. Lignin-based parameters suggest a separate source for terrestrially derived material associated with sand-size material as opposed to that associated with silts and clays.

High surface area LaMnO3 nanoparticles enhancing electrochemical catalytic activity for rechargeable lithium-air batteries

NASA Astrophysics Data System (ADS)

Li, Chuanhua; Yu, Zhiyong; Liu, Hanxing; Chen, Kang

2018-02-01

To improve sluggish kinetics of ORR and OER (oxygen reduction and evolution reaction) on the air electrode, the high surface area LaMnO3 nanoparticle catalysts were synthesized by sol-gel method. The specific surface area of as-synthesized pure phase LaMnO3 nanoparticles is 21.21 m2 g-1. The onset potential of high surface area LaMnO3 in alkaline solution is -0.0202 V which is comparable to commercial Pt/C. When the assembled high surface area LaMnO3-based lithium-air batteries were measured at 100 mA g-1, the initial discharge specific capacity could reach 6851.9 mA h g-1(carbon). In addition, lithium-oxygen batteries including high surface area LaMnO3 catalysts could be cycled for 52 cycles at 200 mA g-1 under a limited discharge-charge depth of 500 mA h gcarbon-1.

Quantifying object and material surface areas in residences

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

Hodgson, Alfred T.; Ming, Katherine Y.; Singer, Brett C.

2005-01-05

The dynamic behavior of volatile organic compounds (VOCs) in indoor environments depends, in part, on sorptive interactions between VOCs in the gas phase and material surfaces. Since information on the types and quantities of interior material surfaces is not generally available, this pilot-scale study was conducted in occupied residences to develop and demonstrate a method for quantifying surface areas of objects and materials in rooms. Access to 33 rooms in nine residences consisting of bathrooms, bedroom/offices and common areas was solicited from among research group members living in the East San Francisco Bay Area. A systematic approach was implemented formore » measuring rooms and objects from 300 cm{sup 2} and larger. The ventilated air volumes of the rooms were estimated and surface area-to-volume ratios were calculated for objects and materials, each segregated into 20 or more categories. Total surface area-to-volume ratios also were determined for each room. The bathrooms had the highest total surface area-to-volume ratios. Bedrooms generally had higher ratios than common areas consisting of kitchens, living/dining rooms and transitional rooms. Total surface area-to-volume ratios for the 12 bedrooms ranged between 2.3 and 4.7 m{sup 2} m{sup -3}. The importance of individual objects and materials with respect to sorption will depend upon the sorption coefficients for the various VOC/materials combinations. When combined, the highly permeable material categories, which may contribute to significant interactions, had a median ratio of about 0.5 m{sup 2} m{sup -3} for all three types of rooms.« less

The role of advanced reactive surface area characterization in improving predictions of mineral reaction rates

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Zhang, S.; Mitnick, E.; Cole, D. R.; Yang, L.; Anovitz, L. M.; Sheets, J.; Swift, A.; Kneafsey, T. J.; Landrot, G.; Mito, S.; Xue, Z.; Steefel, C. I.; DePaolo, D. J.; Ajo Franklin, J. B.

2014-12-01

Geologic sequestration of CO2 in deep sedimentary formations is a promising means of mitigating carbon emissions from coal-fired power plants but the long-term fate of injected CO2 is challenging to predict. Reactive transport models are used to gain insight over long times but rely on laboratory determined mineral reaction rates that have been difficult to extrapolate to field systems. This, in part, is due to a lack of understanding of mineral reactive surface area. Many models use an arbitrary approximation of reactive surface area, applying orders of magnitude scaling factors to measured BET or geometric surface areas. Recently, a few more sophisticated approaches have used 2D and 3D image analyses to determine mineral-specific reactive surface areas that account for the accessibility of minerals. However, the ability of these advanced surface area estimates to improve predictions of mineral reaction rates has yet to be determined. In this study, we fuse X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB analysis to determine mineral-specific accessible reactive surface areas for a core sample from the Nagaoka pilot CO2 injection site (Japan). This sample is primarily quartz, plagioclase, smectite, K-feldspar, and pyroxene. SEM imaging shows abundant smectite cement and grain coatings that decrease the fluid accessibility of other minerals. However, analysis of FIB-SEM images reveals that smectite nano-pores are well connected such that access to underlying minerals is not occluded by smectite coatings. Mineral-specific accessible surfaces are determined, accounting for the connectivity of the pore space with and without connected smectite nano-pores. The large-scale impact of variations in accessibility and dissolution rates are then determined through continuum scale modeling using grid-cell specific information on accessible surface areas. This approach will be compared with a traditional continuum scale model using mineral abundances and common surface area estimates. Ultimately, the effectiveness of advanced surface area characterization to improve mineral dissolution rates will be evaluated by comparison of model results with dissolution rates measured from a flow-through column experiment.

Estimation of small reservoir storage capacities in the São Francisco, Limpopo, Bandama and Volta river basins using remotely sensed surface areas

NASA Astrophysics Data System (ADS)

Rodrigues, Lineu; Senzanje, Aidan; Cecchi, Philippe; Liebe, Jens

2010-05-01

People living in areas with highly variable rainfall, experience droughts and floods and often have insecure livelihoods. Small multi-purpose reservoirs (SR) are a widely used form of infrastructures to provide people in such areas with water during the dry season, e.g. in the basins of São Francisco, Brazil, Limpopo, Zimbabwe, Bandama, Ivory Coast and Volta, Ghana. In these areas, the available natural flow in the streams is sometimes less than the flow required for water supply or irrigation, however water can be stored in times of surplus, for example, from a wet season to a dry season. Efficient water management and sound reservoir planning are hindered by the lack of information about the functioning of these reservoirs. Reservoirs in these regions were constructed in a series of projects funded by different agencies, at different times, with little or no coordination among the implementing partners. Poor record keeping and the lack of appropriate institutional support result in deficiencies of information on the capacity, operation, and maintenance of these structures. Estimating the storage capacity of dams is essential to the responsible management of water diversion. Most of SR in these basins have never been evaluated, possibly because the tools currently used for such measurement are labor-intensive, costly and time-consuming. The objective of this research was to develop methodology to estimate small reservoir capacities as a function of their remotely sensed surface areas in the São Francisco, Limpopo, Bandama and Volta basins, as a way to contribute to improve the water resource management in those catchments. Remote sensing was used to identify, localize and characterize small reservoirs. The surface area of each was calculated from satellite images. A sub-set of reservoirs was selected. For each reservoir in the sub-set, the surface area was estimated from field surveys, and storage capacity was estimated using information on reservoir surface area, depth and shape. Depth was measured using a stadia rod or a manual echosounder. For reservoirs in the sub-set, estimated surface area was used as an input into the triangulated irregular network model. With the surface area and depth, measured volume was calculated. Comparisons were made between estimates of surface area from field surveys and estimates of surface area from remote sensing. A linear regression analysis was carried out to establish the relationship between surface area and storage capacities. Within geomorphologically homogenous regions, one may expect a good correlation between the surface area, which may be determined through satellite observations, and the stored volume. Such a relation depends on the general shape of the slopes (convex, through straight, to concave). The power relationships between remotely sensed surface areas (m^2) and storage capacities of reservoirs (m^3) obtained were - Limpopo basin (Lower Mzingwane sub-catchment): Volume = 0.023083 x Area^1.3272 (R2 = 95%); Bandama basin (North of the basin in Ivory Coast): Volume = 0.00405 x Area^1.4953 (R2 = 88.9%); Volta basin (Upper East region of the Volta Basin in Ghana): Volume = 0.00857 × Area^1.43 (R2 = 97.5%); São Francisco basin (Preto river sub-catchment): Volume = 0.2643 x Area^1.1632 (R2 = 92.1%). Remote sensing was found to be a suitable means to detect small reservoirs and accurately measure their surface areas. The general relationship between measured reservoir volumes and their remotely sensed surface areas showed good accuracy for all four basins. Combining such relationships with periodical satellite-based reservoir area measurements may allow hydrologists and planners to have clear picture of water resource system in the Basins, especially in ungauged sub-basins.

Sex determination using discriminant analysis of upper and lower extremity bones: New approach using the volume and surface area of digital model.

PubMed

Lee, U-Young; Kim, In-Beom; Kwak, Dai-Soon

2015-08-01

This study used 110 CT images taken from donated Korean cadavers to create 3-D models of the following upper and lower limb bones: the clavicle, scapula, humerus, radius, ulna, hip bone (os coxa), femur, patella (knee cap), tibia, talus, and calcaneus. In addition, the bone volume and surface area were calculated to determine sex differences using discriminant analysis. Significant sex differences were found in all bones with respect to volume and surface area (p<0.01). The order of volume was the same in females and males (femur>hip bone>tibia>humerus>scapula), although the order of surface area was different. The largest surface area in men was the femur and in women was the hip bone (p<0.01). An interesting finding of this study was that the ulna is the bone with the highest accuracy for sex determination (94%). When using the surface area of multiple bones, the maximum accuracy (99.4%) was achieved. The equation was as follows: (discriminant equation of surface area; female<0

Proton exchange membrane and electrode surface areas as factors that affect power generation in microbial fuel cells.

PubMed

Oh, Sang-Eun; Logan, Bruce E

2006-03-01

Power generation in microbial fuel cells (MFCs) is a function of the surface areas of the proton exchange membrane (PEM) and the cathode relative to that of the anode. To demonstrate this, the sizes of the anode and cathode were varied in two-chambered MFCs having PEMs with three different surface areas (A (PEM)=3.5, 6.2, or 30.6 cm(2)). For a fixed anode and cathode surface area (A (An)=A (Cat)=22.5 cm(2)), the power density normalized to the anode surface area increased with the PEM size in the order 45 mW/m(2) (A (PEM)=3.5 cm(2)), 68 mW/m(2) (A (PEM)=6.2 cm(2)), and 190 mW/m(2) (A (PEM)=30.6 cm(2)). PEM surface area was shown to limit power output when the surface area of the PEM was smaller than that of the electrodes due to an increase in internal resistance. When the relative cross sections of the PEM, anode, and cathode were scaled according to 2A (Cat)=A(PEM)=2A (An), the maximum power densities of the three different MFCs, based on the surface area of the PEM (A (PEM)=3.5, 6.2, or 30.6 cm(2)), were the same (168+/-4.53 mW/m(2)). Increasing the ionic strength and using ferricyanide at the cathode also increased power output.

Evaluation of airborne lidar elevation surfaces for propagation of coastal inundation: the importance of hydrologic connectivity

USGS Publications Warehouse

Poppenga, Sandra K.; Worstell, Bruce B.

2015-01-01

Detailed information about coastal inundation is vital to understanding dynamic and populated areas that are impacted by storm surge and flooding. To understand these natural hazard risks, lidar elevation surfaces are frequently used to model inundation in coastal areas. A single-value surface method is sometimes used to inundate areas in lidar elevation surfaces that are below a specified elevation value. However, such an approach does not take into consideration hydrologic connectivity between elevation grids cells resulting in inland areas that should be hydrologically connected to the ocean, but are not. Because inland areas that should drain to the ocean are hydrologically disconnected by raised features in a lidar elevation surface, simply raising the water level to propagate coastal inundation will lead to inundation uncertainties. We took advantage of this problem to identify hydrologically disconnected inland areas to point out that they should be considered for coastal inundation, and that a lidar-based hydrologic surface should be developed with hydrologic connectivity prior to inundation analysis. The process of achieving hydrologic connectivity with hydrologic-enforcement is not new, however, the application of hydrologically-enforced lidar elevation surfaces for improved coastal inundation mapping as approached in this research is innovative. In this article, we propagated a high-resolution lidar elevation surface in coastal Staten Island, New York to demonstrate that inland areas lacking hydrologic connectivity to the ocean could potentially be included in inundation delineations. For inland areas that were hydrologically disconnected, we evaluated if drainage to the ocean was evident, and calculated an area exceeding 11 ha (~0.11 km2) that could be considered in inundation delineations. We also assessed land cover for each inland area to determine the type of physical surfaces that would be potentially impacted if the inland areas were considered as part of a coastal inundation. A visual analysis indicated that developed, medium intensity and palustrine forested wetland land cover types would be impacted for those locations. This article demonstrates that hydrologic connectivity is an important factor to consider when inundating a lidar elevation surface. This information is needed for inundation monitoring and management in sensitive coastal regions.

Atrial development in the human heart: an immunohistochemical study with emphasis on the role of mesenchymal tissues

NASA Technical Reports Server (NTRS)

Wessels, A.; Anderson, R. H.; Markwald, R. R.; Webb, S.; Brown, N. A.; Viragh, S.; Moorman, A. F.; Lamers, W. H.

2000-01-01

The development of the atrial chambers in the human heart was investigated immunohistochemically using a set of previously described antibodies. This set included the monoclonal antibody 249-9G9, which enabled us to discriminate the endocardial cushion-derived mesenchymal tissues from those derived from extracardiac splanchnic mesoderm, and a monoclonal antibody recognizing the B isoform of creatine kinase, which allowed us to distinguish the right atrial myocardium from the left. The expression patterns obtained with these antibodies, combined with additional histological information derived from the serial sections, permitted us to describe in detail the morphogenetic events involved in the development of the primary atrial septum (septum primum) and the pulmonary vein in human embryos from Carnegie stage 14 onward. The level of expression of creatine kinase B (CK-B) was found to be consistently higher in the left atrial myocardium than in the right, with a sharp boundary between high and low expression located between the primary septum and the left venous valve indicating that the primary septum is part of the left atrial gene-expression domain. This expression pattern of CK-B is reminiscent of that of the homeobox gene Pitx2, which has recently been shown to be important for atrial septation in the mouse. This study also demonstrates a poorly appreciated role of the dorsal mesocardium in cardiac development. From the earliest stage investigated onward, the mesenchyme of the dorsal mesocardium protrudes into the dorsal wall of the primary atrial segment. This dorsal mesenchymal protrusion is continuous with a mesenchymal cap on the leading edge of the primary atrial septum. Neither the mesenchymal tissues of the dorsal protrusion nor the mesenchymal cap on the edge of the primary septum expressed the endocardial tissue antigen recognized by 249-9G9 at any of the stages investigated. The developing pulmonary vein uses the dorsal mesocardium as a conduit to reach the primary atrial segment. Initially, the pulmonary pit, which will becomes the portal of entry for the pulmonary vein, is located along the midline, flanked by two myocardial ridges. As development progresses, tissue remodeling results in the incorporation of the portal of entry of the pulmonary vein in left atrial myocardium, which is recognized because of its high level of creatine. Closure of the primary atrial foramen by the primary atrial septum occurs as a consequence of the fusion of these mesenchymal structures. Copyright 2000 Wiley-Liss, Inc.

Outflow tract septation and the aortic arch system in reptiles: lessons for understanding the mammalian heart.

PubMed

Poelmann, Robert E; Gittenberger-de Groot, Adriana C; Biermans, Marcel W M; Dolfing, Anne I; Jagessar, Armand; van Hattum, Sam; Hoogenboom, Amanda; Wisse, Lambertus J; Vicente-Steijn, Rebecca; de Bakker, Merijn A G; Vonk, Freek J; Hirasawa, Tatsuya; Kuratani, Shigeru; Richardson, Michael K

2017-01-01

Cardiac outflow tract patterning and cell contribution are studied using an evo-devo approach to reveal insight into the development of aorto-pulmonary septation. We studied embryonic stages of reptile hearts (lizard, turtle and crocodile) and compared these to avian and mammalian development. Immunohistochemistry allowed us to indicate where the essential cell components in the outflow tract and aortic sac were deployed, more specifically endocardial, neural crest and second heart field cells. The neural crest-derived aorto-pulmonary septum separates the pulmonary trunk from both aortae in reptiles, presenting with a left visceral and a right systemic aorta arising from the unseptated ventricle. Second heart field-derived cells function as flow dividers between both aortae and between the two pulmonary arteries. In birds, the left visceral aorta disappears early in development, while the right systemic aorta persists. This leads to a fusion of the aorto-pulmonary septum and the aortic flow divider (second heart field population) forming an avian aorto-pulmonary septal complex. In mammals, there is also a second heart field-derived aortic flow divider, albeit at a more distal site, while the aorto-pulmonary septum separates the aortic trunk from the pulmonary trunk. As in birds there is fusion with second heart field-derived cells albeit from the pulmonary flow divider as the right 6th pharyngeal arch artery disappears, resulting in a mammalian aorto-pulmonary septal complex. In crocodiles, birds and mammals, the main septal and parietal endocardial cushions receive neural crest cells that are functional in fusion and myocardialization of the outflow tract septum. Longer-lasting septation in crocodiles demonstrates a heterochrony in development. In other reptiles with no indication of incursion of neural crest cells, there is either no myocardialized outflow tract septum (lizard) or it is vestigial (turtle). Crocodiles are unique in bearing a central shunt, the foramen of Panizza, between the roots of both aortae. Finally, the soft-shell turtle investigated here exhibits a spongy histology of the developing carotid arteries supposedly related to regulation of blood flow during pharyngeal excretion in this species. This is the first time that is shown that an interplay of second heart field-derived flow dividers with a neural crest-derived cell population is a variable but common, denominator across all species studied for vascular patterning and outflow tract septation. The observed differences in normal development of reptiles may have impact on the understanding of development of human congenital outflow tract malformations.

Atomic force microscopy analysis of different surface treatments of Ti dental implant surfaces

NASA Astrophysics Data System (ADS)

Bathomarco, Ti R. V.; Solorzano, G.; Elias, C. N.; Prioli, R.

2004-06-01

The surface of commercial unalloyed titanium, used in dental implants, was analyzed by atomic force microscopy. The morphology, roughness, and surface area of the samples, submitted to mechanically-induced erosion, chemical etching and a combination of both, were compared. The results show that surface treatments strongly influence the dental implant physical and chemical properties. An analysis of the length dependence of the implant surface roughness shows that, for scan sizes larger than 50 μm, the average surface roughness is independent of the scanning length and that the surface treatments lead to average surface roughness in the range of 0.37 up to 0.48 μm. It is shown that the implant surface energy is sensitive to the titanium surface area. As the area increases there is a decrease in the surface contact angle.

Enhancement of surface area and wettability properties of boron doped diamond by femtosecond laser-induced periodic surface structuring

DOE PAGES

Granados, Eduardo; Calderon, Miguel Martinez; Krzywinski, Jacek; ...

2017-08-28

We demonstrate the formation of laser-induced periodic surface structures (LIPSS) in boron-doped diamond (BDD) by irradiation with femtosecond near-IR laser pulses. The results show that the obtained LIPSS are perpendicular to the laser polarization, and the ripple periodicity is on the order of half of the irradiation wavelength. The surface structures and their electrochemical properties were characterized using Raman micro-spectroscopy, in combination with scanning electron and atomic force microscopies. The textured BDD surface showed a dense and large surface area with no change in its structural characteristics. The effective surface area of the textured BDD electrode was approximately 50% largermore » than that of a planar substrate, while wetting tests showed that the irradiated area becomes highly hydrophilic. Lastly, our results indicate that LIPSS texturing of BDD is a straightforward and simple technique for enhancing the surface area and wettability properties of the BDD electrodes, which could enable higher current efficiency and lower energy consumption in the electrochemical oxidation of toxic organics.« less

Enhancement of surface area and wettability properties of boron doped diamond by femtosecond laser-induced periodic surface structuring

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

Granados, Eduardo; Calderon, Miguel Martinez; Krzywinski, Jacek

We demonstrate the formation of laser-induced periodic surface structures (LIPSS) in boron-doped diamond (BDD) by irradiation with femtosecond near-IR laser pulses. The results show that the obtained LIPSS are perpendicular to the laser polarization, and the ripple periodicity is on the order of half of the irradiation wavelength. The surface structures and their electrochemical properties were characterized using Raman micro-spectroscopy, in combination with scanning electron and atomic force microscopies. The textured BDD surface showed a dense and large surface area with no change in its structural characteristics. The effective surface area of the textured BDD electrode was approximately 50% largermore » than that of a planar substrate, while wetting tests showed that the irradiated area becomes highly hydrophilic. Lastly, our results indicate that LIPSS texturing of BDD is a straightforward and simple technique for enhancing the surface area and wettability properties of the BDD electrodes, which could enable higher current efficiency and lower energy consumption in the electrochemical oxidation of toxic organics.« less

Determination of the surface area of smectite in water by ethylene oxide chain adsorption.

PubMed

Yuang, Paul-Cheng; Shen, Yun-Hwei

2005-05-15

This study investigates the feasibility of using ethylene oxide (EO) chain adsorption to determine the surface area of smectite in water. Experimental results indicate that high-molecular-weight poly(ethylene oxide) (PEO) should be used to provide reasonable estimations for monolayer capacity of PEO on smectite. The surface areas of smectites in water are calculated from the monolayer capacity of PEO adsorbed on smectite by taking the area per EO unit as 8.05 A(2). The method measures the actual surface area of smectite exposed when dispersed in water, which is important to applications of smectite under aqueous conditions.

30 CFR 921.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... surface coal mining operations. 921.764 Section 921.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface...

30 CFR 933.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... surface coal mining operations. 933.764 Section 933.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... mining operations. Part 764 of this chapter, State Processes for Designatng Areas Unsuitable for Surface...

Solar collector having a solid transmission medium

DOEpatents

Schertz, William W.; Zwerdling, Solomon

1977-06-14

There is provided a radiant energy transmission device capable of operation in a concentrative mode in which energy incident on an entrance area is directed toward and concentrated on an exit area of smaller area than the entrance area. The device includes a solid radiant energy transmission medium having surfaces coincident with the entrance and exit areas and particularly contoured reflective side walls. The surface coinciding with the entrance area is coupled to a cover plate formed of a radiant energy transmissive material. An energy transducer is coupled to the surface of the medium coinciding with the exit area.

Determining surface areas of marine alga cells by acid-base titration method.

PubMed

Wang, X; Ma, Y; Su, Y

1997-09-01

A new method for determining the surface area of living marine alga cells was described. The method uses acid-base titration to measure the surface acid/base amount on the surface of alga cells and uses the BET (Brunauer, Emmett, and Teller) equation to estimate the maximum surface acid/base amount, assuming that hydrous cell walls have carbohydrates or other structural compounds which can behave like surface Brönsted acid-base sites due to coordination of environmental H2O molecules. The method was applied to 18 diverse alga species (including 7 diatoms, 2 flagellates, 8 green algae and 1 red alga) maintained in seawater cultures. For the species examined, the surface areas of individual cells ranged from 2.8 x 10(-8) m2 for Nannochloropsis oculata to 690 x 10(-8) m2 for Dunaliella viridis, specific surface areas from 1,030 m2.g-1 for Dunaliella salina to 28,900 m2.g-1 for Pyramidomonas sp. Measurement accuracy was 15.2%. Preliminary studies show that the method may be more promising and accurate than light/electron microscopic measurements for coarse estimation of the surface area of living algae.

Estimating Surface Area of Sponges and Marine Gorgonians as Indicators of Habitat Availability on Caribbean Coral Reefs

EPA Science Inventory

Surface area and topographical complexity are fundamental attributes of shallow tropical coral reefs and can be used to estimate habitat for fish and invertebrates. This study presents empirical methods for estimating surface area provided by sponges and gorgonians in the Central...

30 CFR 77.209 - Surge and storage piles.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Surface... a reclaiming area or in any other area at or near a surge or storage pile where the reclaiming...

Electrode holder useful in a corrosion testing device

DOEpatents

Murphy, R.J. Jr.; Jamison, D.E.

1986-08-19

The present invention is directed to an apparatus and method for holding one or more test electrodes of precisely known exposed surface area. The present invention is particularly useful in a device for determining the corrosion properties of the materials from which the test electrodes have been formed. The present invention relates to a device and method for holding the described electrodes wherein the exposed surface area of the electrodes is only infinitesimally decreased. Further, in the present invention the exposed, electrically conductive surface area of the contact devices is small relative to the test electrode surface area. The holder of the present invention conveniently comprises a device for contacting and engaging each test electrode at two point contacts infinitesimally small in relation to the exposed surface area of the electrodes. 4 figs.

Electrode holder useful in a corrosion testing device

DOEpatents

Murphy, Jr., Robert J.; Jamison, Dale E.

1986-01-01

The present invention is directed to an apparatus and method for holding one or more test electrodes of precisely known exposed surface area. The present invention is particularly useful in a device for determining the corrosion properties of the materials from which the test electrodes have been formed. The present invention relates to a device and method for holding the described electrodes wherein the exposed surface area of the electrodes is only infinitesimally decreased. Further, in the present invention the exposed, electrically conductive surface area of the contact devices is small relative to the test electrode surface area. The holder of the present invention conveniently comprises a device for contacting and engaging each test electrode at two point contacts infinitesimally small in relation to the exposed surface area of the electrodes.

Method for laser welding a fin and a tube

DOEpatents

Fuerschbach, Phillip W.; Mahoney, A. Roderick; Milewski, John O

2001-01-01

A method of laser welding a planar metal surface to a cylindrical metal surface is provided, first placing a planar metal surface into approximate contact with a cylindrical metal surface to form a juncture area to be welded, the planar metal surface and cylindrical metal surface thereby forming an acute angle of contact. A laser beam, produced, for example, by a Nd:YAG pulsed laser, is focused through the acute angle of contact at the juncture area to be welded, with the laser beam heating the juncture area to a welding temperature to cause welding to occur between the planar metal surface and the cylindrical metal surface. Both the planar metal surface and cylindrical metal surface are made from a reflective metal, including copper, copper alloys, stainless steel alloys, aluminum, and aluminum alloys.

Adsorption of water vapour and the specific surface area of arctic zone soils (Spitsbergen)

NASA Astrophysics Data System (ADS)

Cieśla, Jolanta; Sokołowska, Zofia; Witkowska-Walczak, Barbara; Skic, Kamil

2018-01-01

Water vapour/nitrogen adsorption were investigated and calculated the specific surface areas of arctic-zone soil samples (Turbic Cryosols) originating from different micro-relief forms (mud boils, cell forms and sorted circles) and from different depths. For the characterisation of the isotherms obtained for arctic soils, the Brunauer-Emmet-Teller model was then compared with the two other models (Aranovich-Donohue and Guggenheim-Anderson-de Boer) which were developed from Brunauer-Emmet-Teller. Specific surface area was calculated using the Brunauer-Emmet-Teller model at p p0-1 range of 0.05-0.35 for the water vapour desorption and nitrogen adsorption isotherms. The values of total specific surface area were the highest in Cryosols on mud boils, lower on cell forms, and the lowest on sorted circles. Such tendency was observed for the results obtained by both the water vapour and nitrogen adsorption. The differences in the values of specific surface area at two investigated layers were small. High determination coefficients were obtained for relationships between the specific surface areas and contents of clay and silt fraction in Cryosols. No statistically significant correlation between the total carbon amount and the values of specific surface area in Cryosols has been found.

Parcellations and Hemispheric Asymmetries of Human Cerebral Cortex Analyzed on Surface-Based Atlases

PubMed Central

Glasser, Matthew F.; Dierker, Donna L.; Harwell, John; Coalson, Timothy

2012-01-01

We report on surface-based analyses that enhance our understanding of human cortical organization, including its convolutions and its parcellation into many distinct areas. The surface area of human neocortex averages 973 cm2 per hemisphere, based on cortical midthickness surfaces of 2 cohorts of subjects. We implemented a method to register individual subjects to a hybrid version of the FreeSurfer “fsaverage” atlas whose left and right hemispheres are in precise geographic correspondence. Cortical folding patterns in the resultant population-average “fs_LR” midthickness surfaces are remarkably similar in the left and right hemispheres, even in regions showing significant asymmetry in 3D position. Both hemispheres are equal in average surface area, but hotspots of surface area asymmetry are present in the Sylvian Fissure and elsewhere, together with a broad pattern of asymmetries that are significant though small in magnitude. Multiple cortical parcellation schemes registered to the human atlas provide valuable reference data sets for comparisons with other studies. Identified cortical areas vary in size by more than 2 orders of magnitude. The total number of human neocortical areas is estimated to be ∼150 to 200 areas per hemisphere, which is modestly larger than a recent estimate for the macaque. PMID:22047963

The Genetic Association Between Neocortical Volume and General Cognitive Ability Is Driven by Global Surface Area Rather Than Thickness.

PubMed

Vuoksimaa, Eero; Panizzon, Matthew S; Chen, Chi-Hua; Fiecas, Mark; Eyler, Lisa T; Fennema-Notestine, Christine; Hagler, Donald J; Fischl, Bruce; Franz, Carol E; Jak, Amy; Lyons, Michael J; Neale, Michael C; Rinker, Daniel A; Thompson, Wesley K; Tsuang, Ming T; Dale, Anders M; Kremen, William S

2015-08-01

Total gray matter volume is associated with general cognitive ability (GCA), an association mediated by genetic factors. It is expectable that total neocortical volume should be similarly associated with GCA. Neocortical volume is the product of thickness and surface area, but global thickness and surface area are unrelated phenotypically and genetically in humans. The nature of the genetic association between GCA and either of these 2 cortical dimensions has not been examined. Humans possess greater cognitive capacity than other species, and surface area increases appear to be the primary driver of the increased size of the human cortex. Thus, we expected neocortical surface area to be more strongly associated with cognition than thickness. Using multivariate genetic analysis in 515 middle-aged twins, we demonstrated that both the phenotypic and genetic associations between neocortical volume and GCA are driven primarily by surface area rather than thickness. Results were generally similar for each of 4 specific cognitive abilities that comprised the GCA measure. Our results suggest that emphasis on neocortical surface area, rather than thickness, could be more fruitful for elucidating neocortical-GCA associations and identifying specific genes underlying those associations. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Applicability of non-destructive substitutes for leaf area in different stands of Norway spruce (Picea abies L. Karst.) focusing on traditional forest crown measures.

PubMed

Laubhann, Daniel; Eckmüllner, Otto; Sterba, Hubert

2010-09-30

Since individual tree leaf area is an important measure for productivity as well as for site occupancy, it is of high interest in many studies about forest growth. The exact determination of leaf area is nearly impossible. Thus, a common way to get information about leaf area is to use substitutes. These substitutes are often variables which are collected in a destructive way which is not feasible for long term studies. Therefore, this study aimed at testing the applicability of using substitutes for leaf area which could be collected in a non-destructive way, namely crown surface area and crown projection area. In 8 stands of Norway spruce (Picea abies L. Karst.), divided into three age classes and two thinning treatments, a total of 156 trees were felled in order to test the relationship between leaf area and crown surface area and crown projection area, respectively. Individual tree leaf area of the felled sample trees was estimated by 3P-branch sampling with an accuracy of ±10%. Crown projection area and crown surface area were compared with other, more commonly used, but destructive predictors of leaf area, namely sapwood area at different heights on the bole. Our investigations confirmed findings of several studies that sapwood area is the most precise measure for leaf area because of the high correlation between sapwood area and the leaf area. But behind sapwood area at crown base and sapwood area at three tenth of the tree height the predictive ability of crown surface area was ranked third and even better than that of sapwood area at breast height (R(2) = 0.656 compared with 0.600). Within the stands leaf area is proportional to crown surface area. Using the pooled data of all stands a mixed model approach showed that additionally to crown surface area dominant height and diameter at breast height (dbh) improved the leaf area estimates. Thus, taking dominant height and dbh into account, crown surface area can be recommended for estimating the leaf area of individual trees. The resulting model was in line with many other findings on the leaf area and leaf mass relationships with crown size. From the additional influence of dominant height and dbh in the leaf area model we conclude that the used crown model could be improved by estimating the position of the maximum crown width and the crown width at the base of the crown depending on these two variables.

Applicability of non-destructive substitutes for leaf area in different stands of Norway spruce (Picea abies L. Karst.) focusing on traditional forest crown measures

PubMed Central

Laubhann, Daniel; Eckmüllner, Otto; Sterba, Hubert

2010-01-01

Since individual tree leaf area is an important measure for productivity as well as for site occupancy, it is of high interest in many studies about forest growth. The exact determination of leaf area is nearly impossible. Thus, a common way to get information about leaf area is to use substitutes. These substitutes are often variables which are collected in a destructive way which is not feasible for long term studies. Therefore, this study aimed at testing the applicability of using substitutes for leaf area which could be collected in a non-destructive way, namely crown surface area and crown projection area. In 8 stands of Norway spruce (Picea abies L. Karst.), divided into three age classes and two thinning treatments, a total of 156 trees were felled in order to test the relationship between leaf area and crown surface area and crown projection area, respectively. Individual tree leaf area of the felled sample trees was estimated by 3P-branch sampling with an accuracy of ±10%. Crown projection area and crown surface area were compared with other, more commonly used, but destructive predictors of leaf area, namely sapwood area at different heights on the bole. Our investigations confirmed findings of several studies that sapwood area is the most precise measure for leaf area because of the high correlation between sapwood area and the leaf area. But behind sapwood area at crown base and sapwood area at three tenth of the tree height the predictive ability of crown surface area was ranked third and even better than that of sapwood area at breast height (R2 = 0.656 compared with 0.600). Within the stands leaf area is proportional to crown surface area. Using the pooled data of all stands a mixed model approach showed that additionally to crown surface area dominant height and diameter at breast height (dbh) improved the leaf area estimates. Thus, taking dominant height and dbh into account, crown surface area can be recommended for estimating the leaf area of individual trees. The resulting model was in line with many other findings on the leaf area and leaf mass relationships with crown size. From the additional influence of dominant height and dbh in the leaf area model we conclude that the used crown model could be improved by estimating the position of the maximum crown width and the crown width at the base of the crown depending on these two variables. PMID:21072126

Characterizing the fabric of the urban environment: A case study of Salt Lake City, Utah

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

Akbari, Hashem; Rose, L. Shea

2001-02-28

Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective implementation programs. In this report, we discuss the result of a semi-automatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital aerial photographs for Salt Lake City covered a total of about 34 km2 (13 mi2). At 0.50-m resolution, there were approximately 1.4 x 108 pixels of data. Four majormore » land-use types were examined: (1) commercial, (2) industrial, (3) educational, and (4) residential. On average, for the areas studied, vegetation covers about 46 percent of the area (ranging 44-51 percent), roofs cover about 21 percent (ranging 15-24 percent), and paved surfaces about 26 percent (ranging 21-28 percent). For the most part, trees shade streets, parking lots, grass, and sidewalks. In most non-residential areas, paved surfaces cover 46-66 percent of the area. In residential areas, on average, paved surfaces cover about 32 percent of the area. Land-use/land-cover (LU/LC) data from the United States Geological Survey were used to extrapolate these results from neighborhood scales to metropolitan Salt Lake City. In an area of roughly 560 km2, defining most of metropolitan Salt Lake City, over 60 percent is residential. The total roof area is about 110 km2, and the total paved surface area (roads, parking areas, sidewalks) covers about 170 km2. The total vegetated area covers about 230 km2.« less

Color Image of Death Valley, California from SIR-C

NASA Image and Video Library

1999-09-27

This radar image shows the area of Death Valley, California and the different surface types in the area. Radar is sensitive to surface roughness with rough areas showing up brighter than smooth areas, which appear dark.

Estimation of the specific surface area for a porous carrier.

PubMed

Levstek, Meta; Plazl, Igor; Rouse, Joseph D

2010-03-01

In biofilm systems, treatment performance is primarily dependent upon the available biofilm growth surface area in the reactor. Specific surface area is thus a parameter that allows for making comparisons between different carrier technologies used for wastewater treatment. In this study, we estimated the effective surface area for a spherical, porous polyvinyl alcohol (PVA) gel carrier (Kuraray) that has previously demonstrated effectiveness for retention of autotrophic and heterotrophic biomass. This was accomplished by applying the GPS-X modeling tool (Hydromantis) to a comparative analysis of two moving-bed biofilm reactor (MBBR) systems. One system consisted of a lab-scale reactor that was fed synthetic wastewater under autotrophic conditions where only the nitrification process was studied. The other was a pre-denitrification pilot-scale plant that was fed real, primary-settled wastewater. Calibration of an MBBR process model for both systems indicated an effective specific surface area for PVA gel of 2500 m2/m3, versus a specific surface area of 1000 m2/m3 when only the outer surface of the gel beads is considered. In addition, the maximum specific growth rates for autotrophs and heterotrophs were estimated to be 1.2/day and 6.0/day, respectively.

Euclidean Wilson loops and minimal area surfaces in lorentzian AdS 3

DOE PAGES

Irrgang, Andrew; Kruczenski, Martin

2015-12-14

The AdS/CFT correspondence relates Wilson loops in N=4 SYM theory to minimal area surfaces in AdS 5 × S 5 space. If the Wilson loop is Euclidean and confined to a plane (t, x) then the dual surface is Euclidean and lives in Lorentzian AdS 3 c AdS 5. In this paper we study such minimal area surfaces generalizing previous results obtained in the Euclidean case. Since the surfaces we consider have the topology of a disk, the holonomy of the flat current vanishes which is equivalent to the condition that a certain boundary Schrödinger equation has all its solutionsmore » anti-periodic. If the potential for that Schrödinger equation is found then reconstructing the surface and finding the area become simpler. In particular we write a formula for the Area in terms of the Schwarzian derivative of the contour. Finally an infinite parameter family of analytical solutions using Riemann Theta functions is described. In this case, both the area and the shape of the surface are given analytically and used to check the previous results.« less

External Validation of Contact Surface Area as a Predictor of Postoperative Renal Function in Patients Undergoing Partial Nephrectomy.

PubMed

Haifler, Miki; Ristau, Benjamin T; Higgins, Andrew M; Smaldone, Marc C; Kutikov, Alexander; Zisman, Amnon; Uzzo, Robert G

2017-09-20

We sought to externally validate a mathematical formula for tumor contact surface area as a predictor of postoperative renal function in patients undergoing partial nephrectomy for renal cell carcinoma. We queried a prospectively maintained kidney cancer database for patients who underwent partial nephrectomy between 2014 and 2016. Contact surface area was calculated using data obtained from preoperative cross-sectional imaging. The correlation between contact surface area and perioperative variables was examined. The correlation between postoperative renal functional outcomes, contact surface area and the R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, location relative to polar lines and tumor touches main renal artery or vein) nephrometry score was also assessed. A total of 257 patients who underwent partial nephrectomy had sufficient data to enter the study. Median contact surface area was 14.5 cm 2 (IQR 6.2-36) and the median nephrometry score was 9 (IQR 7-10). Spearman correlation analysis showed that contact surface area correlated with estimated blood loss (r s = 0.42, p <0.001), length of stay (r s = 0.18, p = 0.005), and percent and absolute change in the estimated glomerular filtration rate (r s = -0.77 and -0.78, respectively, each p <0.001). On multivariable analysis contact surface area and nephrometry score were independent predictors of the absolute change in the estimated glomerular filtration rate (each p <0.001). ROC curve analysis revealed that contact surface area was a better predictor of a greater than 20% postoperative decline in the estimated glomerular filtration rate compared with the nephrometry score (AUC 0.94 vs 0.80). Contact surface area correlated with the change in postoperative renal function after partial nephrectomy. It can be used in conjunction with the nephrometry score to counsel patients about the risk of renal functional decline after partial nephrectomy. Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Correlation of Superior Canal Dehiscence Surface Area With Vestibular Evoked Myogenic Potentials, Audiometric Thresholds, and Dizziness Handicap.

PubMed

Hunter, Jacob B; O'Connell, Brendan P; Wang, Jianing; Chakravorti, Srijata; Makowiec, Katie; Carlson, Matthew L; Dawant, Benoit; McCaslin, Devin L; Noble, Jack H; Wanna, George B

2016-09-01

To correlate objective measures of vestibular and audiometric function as well as subjective measures of dizziness handicap with the surface area of the superior canal dehiscence (SCD). Retrospective chart review and radiological analysis. Single tertiary academic referral center. Preoperative computed tomography imaging, patient survey, audiometric thresholds, and vestibular evoked myogenic potential (VEMP) testing in patients with confirmed SCD. Image analysis techniques were developed to measure the surface area of each SCD in computed tomography imaging. Preoperative ocular and cervical VEMPs, air and bone conduction thresholds, air-bone gap, dizziness handicap inventory scores, and surface area of the SCD. Fifty-three patients (mean age 52.7 yr) with 84 SCD were analyzed. The median surface area of dehiscence was 1.44 mm (0.068-8.23 mm). Ocular VEMP amplitudes (r = 0.61, p <0.0001), cervical VEMP amplitudes (r = 0.62, p <0.0001), air conduction thresholds at 250 Hz (r = 0.25, p = 0.043), and air-bone gap at 500 Hz (r = 0.27, p = 0.01) positively correlated with increasing size of dehiscence. An inverse relationship between cervical VEMP thresholds (r = -0.56, p < 0.0001) and surface area of the dehiscence was observed. No association between dizziness handicap and surface area was identified. Among patients with confirmed SCD, ocular and cervical VEMP amplitudes, cervical VEMP thresholds, and air conduction thresholds at 250 Hz are significantly correlated with the surface area of the dehiscence.

Synthesis and characterization of high-surface-area millimeter-sized silica beads with hierarchical multi-modal pore structure by the addition of agar

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

Han, Yosep; Choi, Junhyun; Tong, Meiping, E-mail: tongmeiping@iee.pku.edu.cn

2014-04-01

Millimeter-sized spherical silica foams (SSFs) with hierarchical multi-modal pore structure featuring high specific surface area and ordered mesoporous frameworks were successfully prepared using aqueous agar addition, foaming and drop-in-oil processes. The pore-related properties of the prepared spherical silica (SSs) and SSFs were systematically characterized by field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), small-angle X-ray diffraction (SAXRD), Hg intrusion porosimetry, and N{sub 2} adsorption–desorption isotherm measurements. Improvements in the BET surface area and total pore volume were observed at 504 m{sup 2} g{sup −1} and 5.45 cm{sup 3} g{sup −1}, respectively, after an agar addition and foaming process. Despitemore » the increase in the BET surface area, the mesopore wall thickness and the pore size of the mesopores generated from the block copolymer with agar addition were unchanged based on the SAXRD, TEM, and BJH methods. The SSFs prepared in the present study were confirmed to have improved BET surface area and micropore volume through the agar loading, and to exhibit interconnected 3-dimensional network macropore structure leading to the enhancement of total porosity and BET surface area via the foaming process. - Highlights: • Millimeter-sized spherical silica foams (SSFs) are successfully prepared. • SSFs exhibit high BET surface area and ordered hierarchical pore structure. • Agar addition improves BET surface area and micropore volume of SSFs. • Foaming process generates interconnected 3-D network macropore structure of SSFs.« less

Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

PubMed Central

Xue, Chao-Hua; Jia, Shun-Tian; Zhang, Jing; Ma, Jian-Zhong

2010-01-01

This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted. PMID:27877336

An experimental analysis of the real contact area between an electrical contact and a glass plane

NASA Astrophysics Data System (ADS)

Down, Michael; Jiang, Liudi; McBride, John W.

2013-06-01

The exact contact between two rough surfaces is usually estimated using statistical mathematics and surface analysis before and after contact has occurred. To date the majority of real contact and loaded surfaces has been theoretical or by numerical analyses. A method of analysing real contact area under various loads, by utilizing a con-contact laser surface profiler, allows direct measurement of contact area and deformation in terms of contact force and plane displacement between two surfaces. A laser performs a scan through a transparent flat side supported in a fixed position above the base. A test contact, mounted atop a spring and force sensor, and a screw support which moves into contact with the transparent surface. This paper presents the analysis of real contact area of various surfaces under various loads. The surfaces analysed are a pair of Au coated hemispherical contacts, one is a used Au to Au coated multi-walled carbon nanotubes surface, from a MEMS relay application, the other a new contact surface of the same configuration.

Optical method for measuring the surface area of a threaded fastener

Treesearch

Douglas Rammer; Samuel Zelinka

2010-01-01

This article highlights major aspects of a new optical technique to determine the surface area of a threaded fastener; the theoretical framework has been reported elsewhere. Specifically, this article describes general surface area expressions used in the analysis, details of image acquisition system, and major image processing steps contained within the measurement...

Polyvinyl pyridine microspheres

NASA Technical Reports Server (NTRS)

Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

1980-01-01

Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

Polyvinyl pyridine microspheres

NASA Technical Reports Server (NTRS)

Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

1979-01-01

Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

Application of Geographic Information System Methods to Identify Areas Yielding Water that will be Replaced by Water from the Colorado River in the Vidal and Chemehuevi Areas, California, and the Mohave Mesa Area, Arizona

USGS Publications Warehouse

Spangler, Lawrence E.; Angeroth, Cory E.; Walton, Sarah J.

2008-01-01

Relations between the elevation of the static water level in wells and the elevation of the accounting surface within the Colorado River aquifer in the vicinity of Vidal, California, the Chemehuevi Indian Reservation, California, and on Mohave Mesa, Arizona, were used to determine which wells outside the flood plain of the Colorado River are presumed to yield water that will be replaced by water from the Colorado River. Wells that have a static water-level elevation equal to or below the elevation of the accounting surface are presumed to yield water that will be replaced by water from the Colorado River. Geographic Information System (GIS) interpolation tools were used to produce maps of areas where water levels are above, below, and near (within ? 0.84 foot) the accounting surface. Calculated water-level elevations and interpolated accounting-surface elevations were determined for 33 wells in the vicinity of Vidal, 16 wells in the Chemehuevi area, and 35 wells on Mohave Mesa. Water-level measurements generally were taken in the last 10 years with steel and electrical tapes accurate to within hundredths of a foot. A Differential Global Positioning System (DGPS) was used to determine land-surface elevations to within an operational accuracy of ? 0.43 foot, resulting in calculated water-level elevations having a 95-percent confidence interval of ? 0.84 foot. In the Vidal area, differences in elevation between the accounting surface and measured water levels range from -2.7 feet below to as much as 17.6 feet above the accounting surface. Relative differences between the elevation of the water level and the elevation of the accounting surface decrease from west to east and from north to south. In the Chemehuevi area, differences in elevation range from -3.7 feet below to as much as 8.7 feet above the accounting surface, which is established at 449.6 feet in the vicinity of Lake Havasu. In all of the Mohave Mesa area, the water-level elevation is near or below the elevation of the accounting surface. Differences in elevation between water levels and the accounting surface range from -0.2 to -11.3 feet, with most values exceeding -7.0 feet. In general, the ArcGIS Triangulated Irregular Network (TIN) Contour and Natural Neighbor tools reasonably represent areas where the elevation of water levels in wells is above, below, and near (within ? 0.84 foot) the elevation of the accounting surface in the Vidal and Chemehuevi study areas and accurately delineate areas around outlying wells and where anomalies exist. The TIN Contour tool provides a strict linear interpolation while the Natural Neighbor tool provides a smoothed interpolation. Using the default options in ArcGIS, the Inverse Distance Weighted (IDW) and Spline tools also reasonably represent areas above, below, and near the accounting surface in the Vidal and Chemehuevi areas. However, spatial extent of and boundaries between areas above, below, and near the accounting surface vary among the GIS methods, which results largely from the fundamentally different mathematical approaches used by these tools. The limited number and spatial distribution of wells in comparison to the size of the areas, and the locations and relative differences in elevation between water levels and the accounting surface of wells with anomalous water levels also influence the contouring by each of these methods. Qualitatively, the Natural Neighbor tool appears to provide the best representation of the difference between water-level and accounting-surface elevations in the study areas, on the basis of available well data.

Thermal infrared imagery as a tool for analysing the variability of surface saturated areas at various temporal and spatial scales

NASA Astrophysics Data System (ADS)

Glaser, Barbara; Antonelli, Marta; Pfister, Laurent; Klaus, Julian

2017-04-01

Surface saturated areas are important for the on- and offset of hydrological connectivity within the hillslope-riparian-stream continuum. This is reflected in concepts such as variable contributing areas or critical source areas. However, we still lack a standardized method for areal mapping of surface saturation and for observing its spatiotemporal variability. Proof-of-concept studies in recent years have shown the potential of thermal infrared (TIR) imagery to record surface saturation dynamics at various temporal and spatial scales. Thermal infrared imagery is thus a promising alternative to conventional approaches, such as the squishy boot method or the mapping of vegetation. In this study we use TIR images to investigate the variability of surface saturated areas at different temporal and spatial scales in the forested Weierbach catchment (0.45 km2) in western Luxembourg. We took TIR images of the riparian zone with a hand-held FLIR infrared camera at fortnightly intervals over 18 months at nine different locations distributed over the catchment. Not all of the acquired images were suitable for a derivation of the surface saturated areas, as various factors influence the usability of the TIR images (e.g. temperature contrasts, shadows, fog). Nonetheless, we obtained a large number of usable images that provided a good insight into the dynamic behaviour of surface saturated areas at different scales. The images revealed how diverse the evolution of surface saturated areas can be throughout the hydrologic year. For some locations with similar morphology or topography we identified diverging saturation dynamics, while other locations with different morphology / topography showed more similar behaviour. Moreover, we were able to assess the variability of the dynamics of expansion / contraction of saturated areas within the single locations, which can help to better understand the mechanisms behind surface saturation development.

Ground-water and surface-water elevations in the Fairbanks International Airport area, Alaska, 1990-96, and selected geohydrologic report references

USGS Publications Warehouse

Claar, David V.; Lilly, Michael R.

1997-01-01

Ground-water and surface-water elevation data were collected at 61 sites from 1990 to 1996 by the U.S. Geological Survey in cooperation with the Alaska Department of Transportation and Public Facilities, Fairbanks International Airport. Water-surface elevations were measured in 41 ground-water observation wells and at 20 surface-water sites to help characterize the geohydrology of the Fairbanks International Airport area. From 1990 to 1993, data were collected in the vicinity of the former fire-training area at the airport. From 1993 to 1996, the data-collection area was expanded to include the entire airport area. The total number of data-collection sites varied each year because of changing project objectives and increased understanding of the geohydrology in the area.

A novel approach to segmentation and measurement of medical image using level set methods.

PubMed

Chen, Yao-Tien

2017-06-01

The study proposes a novel approach for segmentation and visualization plus value-added surface area and volume measurements for brain medical image analysis. The proposed method contains edge detection and Bayesian based level set segmentation, surface and volume rendering, and surface area and volume measurements for 3D objects of interest (i.e., brain tumor, brain tissue, or whole brain). Two extensions based on edge detection and Bayesian level set are first used to segment 3D objects. Ray casting and a modified marching cubes algorithm are then adopted to facilitate volume and surface visualization of medical-image dataset. To provide physicians with more useful information for diagnosis, the surface area and volume of an examined 3D object are calculated by the techniques of linear algebra and surface integration. Experiment results are finally reported in terms of 3D object extraction, surface and volume rendering, and surface area and volume measurements for medical image analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

a Research on Monitoring Surface Deformation and Relationships with Surface Parameters in Qinghai Tibetan Plateau Permafrost

NASA Astrophysics Data System (ADS)

Mi, S. J.; Li, Y. T.; Wang, F.; Li, L.; Ge, Y.; Luo, L.; Zhang, C. L.; Chen, J. B.

2017-09-01

The Qinghai Tibetan Plateau permafrost has been the largest permafrost region in middle-low latitude in the world for its high altitude. For the large area permafrost, especially surface deformation brought by it, have serious influence on the road engineering, road maintaining and regional economic development. Consequently, it is essential to monitor the surface deformation and study factors that influent it. We monitored an area named Wudaoliang from July 25, 2015 to June 1, 2016 and 15 Sentinel images were obtained during this time. The area we chose is about 35 kilometers long and 2 kilometers wide, and the national road 109 of China passes through the area. The traditional PS-INSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) method is not suitable because less historical images in the research area and leading to the number of PS (Persistent Scatterer) points is not enough to obtain accurate deformation results. Therefore, in this paper, we used another method which named QUASI-PSInSAR (QUASI Persistent Scatterer Interferometric Synthetic Aperture Radar) to acquire deformation for it has the advantage to weaken or eliminate the effects of spatial and temporal correlation, which has proved by other scholar. After processing 15 images in the SARproz software, we got the conclusions that, 1) the biggest deformation velocity in the whole area was about 127.9mm/year and about 109.3 mm/year in the road; 2) apparent deformation which have surface deformation more than 30mm/year was about 1.7Km in the road. Meanwhile, soil moisture(SM), Land surface temperature (LST) and surface water(SW), which are primary parameters of the land surface over the same time were reversed by using Sentinel data, Landsat data and ZY-3 data, respectively. After analyzing SM, LST , SW and deformation, we obtained that wet areas which had bigger SM, lower LST and more SW, had greater percentage of severe deformation than arid areas; besides, deformation pattern were different in arid areas and wet areas. During the research time, frost heaving firstly accounted for a large proportion both in the arid and wet areas with the decrease of downward radiation from July to December; after December, thaw settlement came into prominence with the increase downward radiation in the arid areas, while in the wet areas, surface put into diverse situations because of water transformation leading to severe deformation. In summary, soil moisture is an important factor that influences the surface deformation. This relationship between deformation process and soil moisture will be researched more in our further work.

Surface area-volume ratios in insects.

PubMed

Kühsel, Sara; Brückner, Adrian; Schmelzle, Sebastian; Heethoff, Michael; Blüthgen, Nico

2017-10-01

Body mass, volume and surface area are important for many aspects of the physiology and performance of species. Whereas body mass scaling received a lot of attention in the literature, surface areas of animals have not been measured explicitly in this context. We quantified surface area-volume (SA/V) ratios for the first time using 3D surface models based on a structured light scanning method for 126 species of pollinating insects from 4 orders (Diptera, Hymenoptera, Lepidoptera, and Coleoptera). Water loss of 67 species was measured gravimetrically at very dry conditions for 2 h at 15 and 30 °C to demonstrate the applicability of the new 3D surface measurements and relevance for predicting the performance of insects. Quantified SA/V ratios significantly explained the variation in water loss across species, both directly or after accounting for isometric scaling (residuals of the SA/V ∼ mass 2/3 relationship). Small insects with a proportionally larger surface area had the highest water loss rates. Surface scans of insects to quantify allometric SA/V ratios thus provide a promising method to predict physiological responses, improving the potential of body mass isometry alone that assume geometric similarity. © 2016 Institute of Zoology, Chinese Academy of Sciences.

A simultaneous multichannel monophasic action potential electrode array for in vivo epicardial repolarization mapping.

PubMed

Sahakian, A V; Peterson, M S; Shkurovich, S; Hamer, M; Votapka, T; Ji, T; Swiryn, S

2001-03-01

While the recording of extracellular monophasic action potentials (MAPs) from single epicardial or endocardial sites has been performed for over a century, we are unaware of any previous successful attempt to record MAPs simultaneously from a large number of sites in vivo. We report here the design and validation of an array of MAP electrodes which records both depolarization and repolarization simultaneously at up to 16 epicardial sites in a square array on the heart in vivo. The array consists of 16 sintered Ag-AgCl electrodes mounted in a common housing with individual suspensions allowing each electrode to exert a controlled pressure on the epicardial surface. The electrodes are arranged in a square array, with each quadrant of four having an additional recessed sintered Ag-AgCl reference electrode at its center. A saline-soaked sponge establishes ionic contact between the reference electrodes and the tissue. The array was tested on six anesthetized open-chested pigs. Simultaneous diagnostic-quality MAP recordings were obtained from up to 13 out of 16 ventricular sites. Ventricular MAPs had amplitudes of 10-40 mV with uniform morphologies and stable baselines for up to 30 min. MAP duration at 90% repolarization was measured and shown to vary as expected with cycle length during sustained pacing. The relationship between MAP duration and effective refractory period was also confirmed. The ability of the array to detect local differences in repolarization was tested in two ways. Placement of the array straddling the atrioventricular (AV) junction yielded simultaneous atrial or ventricular recordings at corresponding sites during 1:1 and 2:1 AV conduction. Localized ischemia via constriction of a coronary artery branch resulted in shortening of the repolarization phase at the ischemic, but not the nonischemic, sites. In conclusion, these results indicate that the simultaneous multichannel MAP electrode array is a viable method for in vivo epicardial repolarization mapping. The array has the potential to be expanded to increase the number of sites and spatial resolution.

Segmentation of real-time three-dimensional ultrasound for quantification of ventricular function: a clinical study on right and left ventricles.

PubMed

Angelini, Elsa D; Homma, Shunichi; Pearson, Gregory; Holmes, Jeffrey W; Laine, Andrew F

2005-09-01

Among screening modalities, echocardiography is the fastest, least expensive and least invasive method for imaging the heart. A new generation of three-dimensional (3-D) ultrasound (US) technology has been developed with real-time 3-D (RT3-D) matrix phased-array transducers. These transducers allow interactive 3-D visualization of cardiac anatomy and fast ventricular volume estimation without tomographic interpolation as required with earlier 3-D US acquisition systems. However, real-time acquisition speed is performed at the cost of decreasing spatial resolution, leading to echocardiographic data with poor definition of anatomical structures and high levels of speckle noise. The poor quality of the US signal has limited the acceptance of RT3-D US technology in clinical practice, despite the wealth of information acquired by this system, far greater than with any other existing echocardiography screening modality. We present, in this work, a clinical study for segmentation of right and left ventricular volumes using RT3-D US. A preprocessing of the volumetric data sets was performed using spatiotemporal brushlet denoising, as presented in previous articles Two deformable-model segmentation methods were implemented in 2-D using a parametric formulation and in 3-D using an implicit formulation with a level set implementation for extraction of endocardial surfaces on denoised RT3-D US data. A complete and rigorous validation of the segmentation methods was carried out for quantification of left and right ventricular volumes and ejection fraction, including comparison of measurements with cardiac magnetic resonance imaging as the reference. Results for volume and ejection fraction measurements report good performance of quantification of cardiac function on RT3-D data compared with magnetic resonance imaging with better performance of semiautomatic segmentation methods than with manual tracing on the US data.

Developmental expression of membrane type 4-matrix metalloproteinase (Mt4-mmp/Mmp17) in the mouse embryo

PubMed Central

Clemente, Cristina; Montalvo, María Gregoria; Seiki, Motoharu; Arroyo, Alicia G.

2017-01-01

Matrix metalloproteinases (MMPs) constitute a large group of endoproteases that play important functions during embryonic development, tumor metastasis and angiogenesis by degrading components of the extracellular matrix. Within this family, we focused our study on Mt4-mmp (also called Mmp17) that belongs to a distinct subset that is anchored to the cell surface via a glycosylphosphatidylinositol (GPI) moiety and with the catalytic site exposed to the extracellular space. Information about its function and substrates is very limited to date, and little has been reported on its role in the developing embryo. Here, we report a detailed expression analysis of Mt4-mmp during mouse embryonic development by using a LacZ reporter transgenic mouse line. We showed that Mt4-mmp is detected from early stages of development to postnatal stages following a dynamic and restricted pattern of expression. Mt4-mmp was first detected at E8.5 limited to the intersomitic vascularization, the endocardial endothelium and the dorsal aorta. Mt4-mmpLacZ/+ cells were also observed in the neural crest cells, somites, floor plate and notochord at early stages. From E10.5, expression localized in the limb buds and persists during limb development. A strong expression in the brain begins at E12.5 and continues to postnatal stages. Specifically, staining was observed in the olfactory bulb, cerebral cortex, hippocampus, striatum, septum, dorsal thalamus and the spinal cord. In addition, LacZ-positive cells were also detected during eye development, initially at the hyaloid artery and later on located in the lens and the neural retina. Mt4-mmp expression was confirmed by quantitative RT-PCR and western blot analysis in some embryonic tissues. Our data point to distinct functions for this metalloproteinase during embryonic development, particularly during brain formation, angiogenesis and limb development. PMID:28926609

Pneumatic Distension of Ventricular Mural Architecture Validated Histologically.

PubMed

Burg, M C; Lunkenheimer, P; Niederer, P; Brune, C; Redmann, K; Smerup, M; Spiegel, U; Becker, F; Maintz, D; Heindel, W; Anderson, R H

2016-11-01

Purpose: There are ongoing arguments as to how cardiomyocytes are aggregated together within the ventricular walls. We used pneumatic distension through the coronary arteries to exaggerate the gaps between the aggregated cardiomyocytes, analyzing the pattern revealed using computed tomography, and validating our findings by histology. Methods: We distended 10 porcine hearts, arresting 4 in diastole by infusion of cardioplegic solutions, and 4 in systole by injection of barium chloride. Mural architecture was revealed by computed tomography, measuring also the angulations of the long chains of cardiomyocytes. We prepared the remaining 2 hearts for histology by perfusion with formaldehyde. Results: Increasing pressures of pneumatic distension elongated the ventricular walls, but produced insignificant changes in mural thickness. The distension exaggerated the spaces between the aggregated cardiomyocytes, compartmenting the walls into epicardial, central, and endocardial regions, with a feathered arrangement of transitions between them. Marked variation was noted in the thicknesses of the parts in the different ventricular segments, with no visible anatomical boundaries between them. Measurements of angulations revealed intruding and extruding populations of cardiomyocytes that deviated from a surface-parallel alignment. Scrolling through the stacks of tomographic images revealed marked spiraling of the aggregated cardiomyocytes when traced from base to apex. Conclusion: Our findings call into question the current assumption that cardiomyocytes are uniformly aggregated together in a tangential fashion. There is marked heterogeneity in the architecture of the different ventricular segments, with the aggregated units never extending in a fully transmural fashion. Key Points: • Pneumographic computed tomography reveals an organized structure of the ventricular walls.• Aggregated cardiomyocytes form a structured continuum, with marked regional heterogeneity.• Global ventricular function results from antagonistic forces generated by aggregated cardiomyocytes. Citation Format: • Burg MC, Lunkenheimer P, Niederer P et al. Pneumatic Distension of Ventricular Mural Architecture Validated Histologically. Fortschr Röntgenstr 2016; 188: 1045 - 1053. © Georg Thieme Verlag KG Stuttgart · New York.

Comparison of Exposure in the Kaplan Versus the Kocher Approach in the Treatment of Radial Head Fractures.

PubMed

Barnes, Leslie Fink; Lombardi, Joseph; Gardner, Thomas R; Strauch, Robert J; Rosenwasser, Melvin P

2018-01-01

The aim of this study was to compare the complete visible surface area of the radial head, neck, and coronoid in the Kaplan and Kocher approaches to the lateral elbow. The hypothesis was that the Kaplan approach would afford greater visibility due to the differential anatomy of the intermuscular planes. Ten cadavers were dissected with the Kaplan and Kocher approaches, and the visible surface area was measured in situ using a 3-dimensional digitizer. Six measurements were taken for each approach by 2 surgeons, and the mean of these measurements were analyzed. The mean surface area visible with the lateral collateral ligament (LCL) preserved in the Kaplan approach was 616.6 mm 2 in comparison with the surface area of 136.2 mm 2 visible in the Kocher approach when the LCL was preserved. Using a 2-way analysis of variance, the difference between these 2 approaches was statistically significant. When the LCL complex was incised in the Kocher approach, the average visible surface area of the Kocher approach was 456.1 mm 2 and was statistically less than the Kaplan approach. The average surface area of the coronoid visible using a proximally extended Kaplan approach was 197.8 mm 2 . The Kaplan approach affords significantly greater visible surface area of the proximal radius than the Kocher approach.

High Surface Area Dendrite Nanoelectrodes for Electrochemistry

NASA Astrophysics Data System (ADS)

Nesbitt, Nathan; Glover, Jennifer; Goyal, Saurabh; Simidjiysky, Svetoslav; Naughton, Michael

2014-03-01

Solution-based electrodeposition of metal using a low ion concentration, surface passivation agents, and/or electrochemical crystal conditioning has allowed for the formation of high surface area metal electrodes, useful for Raman spectroscopy and electrochemical sensors. Additionally, high frequency electrical oscillations have been used to electrically connect co-planar electrodes, a process called directed electrochemical nanowire assembly (DENA). These approaches aim to control the crystal face that metal atoms in solution will nucleate onto, thus causing anisotropic growth of metal crystals. However, DENA has not been used to create high surface area electrodes, and no study has been conducted on the effect of micron-scale surface topography on the initial nucleation of metal crystals on the electrode surface. When DENA is used to create a high surface area electrode, such a texture has a strong impact on the subsequent topography of the three dimensional dendritic structures by limiting the areal density of crystals on the electrode surface. Such structures both demonstrate unique physics concerning the nucleation of metal dendrites, and offer a unique and highly facile fabrication method of high surface area electrodes, useful for chemical and biological sensing. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. (DGE-1258923).

Impact of land cover change on the environmental hydrology characteristics in Kelantan river basin, Malaysia

NASA Astrophysics Data System (ADS)

Saadatkhah, Nader; Mansor, Shattri; Khuzaimah, Zailani; Asmat, Arnis; Adnan, Noraizam; Adam, Siti Noradzah

2016-09-01

Changing the land cover/ land use has serious environmental impacts affecting the ecosystem in Malaysia. The impact of land cover changes on the environmental functions such as surface water, loss water, and soil moisture is considered in this paper on the Kelantan river basin. The study area at the east coast of the peninsular Malaysia has suffered significant land cover changes in the recent years. The current research tried to assess the impact of land cover changes in the study area focused on the surface water, loss water, and soil moisture from different land use classes and the potential impact of land cover changes on the ecosystem of Kelantan river basin. To simulate the impact of land cover changes on the environmental hydrology characteristics, a deterministic regional modeling were employed in this study based on five approaches, i.e. (1) Land cover classification based on Landsat images; (2) assessment of land cover changes during last three decades; (3) Calculation the rate of water Loss/ Infiltration; (4) Assessment of hydrological and mechanical effects of the land cover changes on the surface water; and (5) evaluation the impact of land cover changes on the ecosystem of the study area. Assessment of land cover impact on the environmental hydrology was computed with the improved transient rainfall infiltration and grid based regional model (Improved-TRIGRS) based on the transient infiltration, and subsequently changes in the surface water, due to precipitation events. The results showed the direct increased in surface water from development area, agricultural area, and grassland regions compared with surface water from other land covered areas in the study area. The urban areas or lower planting density areas tend to increase for surface water during the monsoon seasons, whereas the inter flow from forested and secondary jungle areas contributes to the normal surface water.

Evaluation of a technique for satellite-derived area estimation of forest fires

NASA Technical Reports Server (NTRS)

Cahoon, Donald R., Jr.; Stocks, Brian J.; Levine, Joel S.; Cofer, Wesley R., III; Chung, Charles C.

1992-01-01

The advanced very high resolution radiometer (AVHRR), has been found useful for the location and monitoring of both smoke and fires because of the daily observations, the large geographical coverage of the imagery, the spectral characteristics of the instrument, and the spatial resolution of the instrument. This paper will discuss the application of AVHRR data to assess the geographical extent of burning. Methods have been developed to estimate the surface area of burning by analyzing the surface area effected by fire with AVHRR imagery. Characteristics of the AVHRR instrument, its orbit, field of view, and archived data sets are discussed relative to the unique surface area of each pixel. The errors associated with this surface area estimation technique are determined using AVHRR-derived area estimates of target regions with known sizes. This technique is used to evaluate the area burned during the Yellowstone fires of 1988.

Area G Perimeter Surface-Soil Sampling Environmental Surveillance for Fiscal Year 1998 Hazardous and Solid Waste Group (ESH-19)

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

Marquis Childs

1999-09-01

Material Disposal Area G (Area G) is at Technical Area 54 at Los Alamos National Laboratory (LANL). Area G has been the principal facility for the disposal of low-level, solid-mixed, and transuranic waste since 1957. It is currently LANL's primary facility for radioactive solid waste burial and storage. As part of the annual environmental surveillance effort at Area G, surface soil samples are collected around the facility's perimeter to characterize possible radionuclide movement off the site through surface water runoff During 1998, 39 soil samples were collected and analyzed for percent moisture, tritium, plutonium-238 and 239, cesium-137 and americium-241. Tomore » assess radionuclide concentrations, the results from these samples are compared with baseline or background soil samples collected in an undisturbed area west of the active portion Area G. The 1998 results are also compared to the results from analogous samples collected during 1996 and 1997 to assess changes over this time in radionuclide activity concentrations in surface soils around the perimeter of Area G. The results indicate elevated levels of all the radionuclides assessed (except cesium-137) exist in Area G perimeter surface soils vs the baseline soils. The comparison of 1998 soil data to previous years (1996 and 1997) indicates no significant increase or decrease in radionuclide concentrations; an upward or downward trend in concentrations is not detectable at this time. These results are consistent with data comparisons done in previous years. Continued annual soil sampling will be necessary to realize a trend if one exists. The radionuclide levels found in the perimeter surface soils are above background but still considered relatively low. This perimeter surface soil data will be used for planning purposes at Area G, techniques to prevent sediment tm.nsport off-site are implemented in the areas where the highest radionuclide concentrations are indicated.« less

Why Do We Need the Derivative for the Surface Area?

ERIC Educational Resources Information Center

Hristova, Yulia; Zeytuncu, Yunus E.

2016-01-01

Surface area and volume computations are the most common applications of integration in calculus books. When computing the surface area of a solid of revolution, students are usually told to use the frustum method instead of the disc method; however, a rigorous explanation is rarely provided. In this note, we provide one by using geometric…

The Effects of 3D-Representation Instruction on Composite-Solid Surface-Area Learning for Elementary School Students

ERIC Educational Resources Information Center

Sung, Yao-Ting; Shih, Pao-Chen; Chang, Kuo-En

2015-01-01

Providing instruction on spatial geometry, specifically how to calculate the surface areas of composite solids, challenges many elementary school teachers. Determining the surface areas of composite solids involves complex calculations and advanced spatial concepts. The goals of this study were to build on students' learning processes for…

Thermionic gas switch

DOEpatents

Hatch, G.L.; Brummond, W.A.; Barrus, D.M.

1984-04-05

The present invention is directed to an improved temperature responsive thermionic gas switch utilizing a hollow cathode and a folded emitter surface area. The folded emitter surface area of the thermionic switch substantially increases the on/off ratio by changing the conduction surface area involved in the two modes thereof. The improved switch of this invention provides an on/off ratio of 450:1 compared to the 10:1 ratio of the prior known thermionic switch, while providing for adjusting the on current. In the improved switch of this invention the conduction area is made small in the off mode, while in the on mode the conduction area is made large. This is achieved by utilizing a folded hollow cathode configuration and utilizing a folded emitter surface area, and by making the dimensions of the folds small enough so that a space charge will develop in the convolutions of the folds and suppress unignited current, thus limiting the current carrying surface in the off mode.

The relationship between epicuticular long-chained hydrocarbons and surface area - volume ratios in insects (Diptera, Hymenoptera, Lepidoptera)

PubMed Central

Brückner, Adrian; Heethoff, Michael; Blüthgen, Nico

2017-01-01

Long-chain cuticular hydrocarbons (CHCs) are common components of the epicuticle of terrestrial arthropods. CHC serve as a protective barrier against environmental influences but also act as semiochemicals in animal communication. Regarding the latter aspect, species- or intra-functional group specific CHCs composition and variation are relatively well studied. However, comparative knowledge about the relationship of CHC quantity and their relation to surface area—volume ratios in the context of water loss and protection is fragmentary. Hence, we aim to study the taxon-specific relationship of the CHC amount and surface-area to volume ratio related to their functional role (e.g. in water loss). We focused on flower visiting insects and analyzed the CHC amounts of three insect orders (Hymenoptera, Lepidoptera and Diptera) using gas chromatography—mass spectrometry (GC-MS). We included 113 species from two grassland plots, quantified their CHCs, and measured their body mass and surface area. We found differences in the surface area, CHCs per body mass and the CHC density (= amount of CHCs per surface area) across the three insect taxa. Especially the Hymenoptera had a higher CHC density compared to Diptera and Lepidoptera. CHC density could be explained by surface area-volume ratios in Hymenoptera but not in Diptera and Lepidoptera. Unexpectedly, CHC density decreased with increasing surface area—volume ratios. PMID:28384308

The impact of surface area, volume, curvature, and Lennard-Jones potential to solvation modeling.

PubMed

Nguyen, Duc D; Wei, Guo-Wei

2017-01-05

This article explores the impact of surface area, volume, curvature, and Lennard-Jones (LJ) potential on solvation free energy predictions. Rigidity surfaces are utilized to generate robust analytical expressions for maximum, minimum, mean, and Gaussian curvatures of solvent-solute interfaces, and define a generalized Poisson-Boltzmann (GPB) equation with a smooth dielectric profile. Extensive correlation analysis is performed to examine the linear dependence of surface area, surface enclosed volume, maximum curvature, minimum curvature, mean curvature, and Gaussian curvature for solvation modeling. It is found that surface area and surfaces enclosed volumes are highly correlated to each other's, and poorly correlated to various curvatures for six test sets of molecules. Different curvatures are weakly correlated to each other for six test sets of molecules, but are strongly correlated to each other within each test set of molecules. Based on correlation analysis, we construct twenty six nontrivial nonpolar solvation models. Our numerical results reveal that the LJ potential plays a vital role in nonpolar solvation modeling, especially for molecules involving strong van der Waals interactions. It is found that curvatures are at least as important as surface area or surface enclosed volume in nonpolar solvation modeling. In conjugation with the GPB model, various curvature-based nonpolar solvation models are shown to offer some of the best solvation free energy predictions for a wide range of test sets. For example, root mean square errors from a model constituting surface area, volume, mean curvature, and LJ potential are less than 0.42 kcal/mol for all test sets. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Effects of surface tension and intraluminal fluid on mechanics of small airways.

PubMed

Hill, M J; Wilson, T A; Lambert, R K

1997-01-01

Airway constriction is accompanied by folding of the mucosa to form ridges that run axially along the inner surface of the airways. The mucosa has been modeled (R. K. Lambert. J. Appl. Physiol. 71:666-673, 1991) as a thin elastic layer with a finite bending stiffness, and the contribution of its bending stiffness to airway elastance has been computed. In this study, we extend that work by including surface tension and intraluminal fluid in the model. With surface tension, the pressure on the inner surface of the elastic mucosa is modified by the pressure difference across the air-liquid interface. As folds form in the mucosa, intraluminal fluid collects in pools in the depressions formed by the folds, and the curvature of the air-liquid interface becomes nonuniform. If the amount of intraluminal fluid is small, < 2% of luminal volume, the pools of intraluminal fluid are small, the air-liquid interface nearly coincides with the surface of the mucosa, and the area of the air-liquid interface remains constant as airway cross-sectional area decreases. In that case, surface energy is independent of airway area, and surface tension has no effect on airway mechanics. If the amount of intraluminal fluid is > 2%, the area of the air-liquid interface decreases as airway cross-sectional area decreases. and surface tension contributes to airway compression. The model predicts that surface tension plus intraluminal fluid can cause an instability in the area-pressure curve of small airways. This instability provides a mechanism for abrupt airway closure and abrupt reopening at a higher opening pressure.

On the accuracy of stratospheric aerosol extinction derived from in situ size distribution measurements and surface area density derived from remote SAGE II and HALOE extinction measurements

DOE PAGES

Kovilakam, Mahesh; Deshler, Terry

2015-08-26

In situ stratospheric aerosol measurements, from University of Wyoming optical particle counters (OPCs), are compared with Stratospheric Aerosol Gas Experiment (SAGE) II (versions 6.2 and 7.0) and Halogen Occultation Experiment (HALOE) satellite measurements to investigate differences between SAGE II/HALOE-measured extinction and derived surface area and OPC-derived extinction and surface area. Coincident OPC and SAGE II measurements are compared for a volcanic (1991-1996) and nonvolcanic (1997-2005) period. OPC calculated extinctions agree with SAGE II measurements, within instrumental uncertainty, during the volcanic period, but have been a factor of 2 low during the nonvolcanic period. Three systematic errors associated with the OPCmore » measurements, anisokineticity, inlet particle evaporation, and counting efficiency, were investigated. An overestimation of the OPC counting efficiency is found to be the major source of systematic error. With this correction OPC calculated extinction increases by 15-30% (30-50%) for the volcanic (nonvolcanic) measurements. These changes significantly improve the comparison with SAGE II and HALOE extinctions in the nonvolcanic cases but slightly degrade the agreement in the volcanic period. These corrections have impacts on OPC-derived surface area density, exacerbating the poor agreement between OPC and SAGE II (version 6.2) surface areas. Furthermore, this disparity is reconciled with SAGE II version 7.0 surface areas. For both the volcanic and nonvolcanic cases these changes in OPC counting efficiency and in the operational SAGE II surface area algorithm leave the derived surface areas from both platforms in significantly better agreement and within the ± 40% precision of the OPC moment calculations.« less

On the accuracy of stratospheric aerosol extinction derived from in situ size distribution measurements and surface area density derived from remote SAGE II and HALOE extinction measurements

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

Kovilakam, Mahesh; Deshler, Terry

In situ stratospheric aerosol measurements, from University of Wyoming optical particle counters (OPCs), are compared with Stratospheric Aerosol Gas Experiment (SAGE) II (versions 6.2 and 7.0) and Halogen Occultation Experiment (HALOE) satellite measurements to investigate differences between SAGE II/HALOE-measured extinction and derived surface area and OPC-derived extinction and surface area. Coincident OPC and SAGE II measurements are compared for a volcanic (1991-1996) and nonvolcanic (1997-2005) period. OPC calculated extinctions agree with SAGE II measurements, within instrumental uncertainty, during the volcanic period, but have been a factor of 2 low during the nonvolcanic period. Three systematic errors associated with the OPCmore » measurements, anisokineticity, inlet particle evaporation, and counting efficiency, were investigated. An overestimation of the OPC counting efficiency is found to be the major source of systematic error. With this correction OPC calculated extinction increases by 15-30% (30-50%) for the volcanic (nonvolcanic) measurements. These changes significantly improve the comparison with SAGE II and HALOE extinctions in the nonvolcanic cases but slightly degrade the agreement in the volcanic period. These corrections have impacts on OPC-derived surface area density, exacerbating the poor agreement between OPC and SAGE II (version 6.2) surface areas. Furthermore, this disparity is reconciled with SAGE II version 7.0 surface areas. For both the volcanic and nonvolcanic cases these changes in OPC counting efficiency and in the operational SAGE II surface area algorithm leave the derived surface areas from both platforms in significantly better agreement and within the ± 40% precision of the OPC moment calculations.« less

Volume to Surface Area Ratios of Foraminifera over the Phanerozoic

NASA Astrophysics Data System (ADS)

Cheung, K.; Gomez, D.; Guo, D.; Jost, A.; Payne, J.

2010-12-01

Although there have been numerous studies regarding the issue of the volume to surface area ratio, no study has been extensive enough to include over 35000 species of foraminifera. The Stanford Paleobiology lab undertook the enormous task of extracting from the Catalogue of Foraminifera, by Ellis and Messina, all relevant data of the foraminifera, such as the three dimensions of the organism, the magnification, and the time period in which the organism existed. For the purpose of calculating the volume and surface area, the foraminifera were generalized as ellipsoids. It is known that the surface area of foraminifera represents where the exchange between the interior body and exterior environment of the foraminifera occurs. The volume of the foraminifera indicates the physical needs of the foraminifera. With more volume in foraminifera, more body functions are occurring and more exterior resources are needed to sustain those bodily functions. Thus with a larger volume to surface area ratio, foraminifera are disadvantaged because they must use more effort in order to acquire adequate resources to fulfill their biological needs. So, the hypothesis is that when there is an increase in oxygen (a vital exterior resource of the foraminifera), the average volume to surface area ratio would be greater because the abundance of oxygen allows foraminifera to work with greater ease in maintaining an exterior resource that they cannot survive without. To prove or refute this assertion, graphs were generated in this study; the graphs indeed suggested that there is a correlation between the volume to surface area ratios and oxygen levels, illustrating that it is plausible that oxygen is a limiting factor of the volume to surface area ratio in foraminifera.

Aquatic adaptations in the nose of carnivorans: evidence from the turbinates

PubMed Central

Van Valkenburgh, Blaire; Curtis, Abigail; Samuels, Joshua X; Bird, Deborah; Fulkerson, Brian; Meachen-Samuels, Julie; Slater, Graham J

2011-01-01

Inside the mammalian nose lies a labyrinth of bony plates covered in epithelium collectively known as turbinates. Respiratory turbinates lie anteriorly and aid in heat and water conservation, while more posterior olfactory turbinates function in olfaction. Previous observations on a few carnivorans revealed that aquatic species have relatively large, complex respiratory turbinates and greatly reduced olfactory turbinates compared with terrestrial species. Body heat is lost more quickly in water than air and increased respiratory surface area likely evolved to minimize heat loss. At the same time, olfactory surface area probably diminished due to a decreased reliance on olfaction when foraging under water. To explore how widespread these adaptations are, we documented scaling of respiratory and olfactory turbinate surface area with body size in a variety of terrestrial, freshwater, and marine carnivorans, including pinnipeds, mustelids, ursids, and procyonids. Surface areas were estimated from high-resolution CT scans of dry skulls, a novel approach that enabled a greater sampling of taxa than is practical with fresh heads. Total turbinate, respiratory, and olfactory surface areas correlate well with body size (r2 ≥ 0.7), and are relatively smaller in larger species. Relative to body mass or skull length, aquatic species have significantly less olfactory surface area than terrestrial species. Furthermore, the ratio of olfactory to respiratory surface area is associated with habitat. Using phylogenetic comparative methods, we found strong support for convergence on 1 : 3 proportions in aquatic taxa and near the inverse in terrestrial taxa, indicating that aquatic mustelids and pinnipeds independently acquired similar proportions of olfactory to respiratory turbinates. Constraints on turbinate surface area in the nasal chamber may result in a trade-off between respiratory and olfactory function in aquatic mammals. PMID:21198587

An easy-to-use approach for determining the disintegration ability of disintegrants by analysis of available surface area.

PubMed

Iwao, Yasunori; Tanaka, Shoko; Uchimoto, Takeaki; Noguchi, Shuji; Itai, Shigeru

2013-05-01

With the aim of directly predicting the functionality and mechanism of disintegrants during the disintegration and dissolution of tablets, we investigated an analysis method based on available surface area, which is the surface area of a drug in a formulation in direct contact with the external solvent during dissolution. We evaluated the following disintegrants in this study: sodium starch glycolate (Glycolys), crospovidone (Kollidon CL), carboxymethylcellulose calcium (CMC-Ca), low-substituted hydroxypropylcellulose (L-HPC), and croscarmellose sodium (Ac-Di-Sol). When disintegrant was added to a 50% ethenzamide tablet formulation, an increase in the dissolution rate dependent on disintegrant concentration was observed, according to the type of disintegrant. In addition, the available surface area also differed between disintegrants. For Glycolys, CMC-Ca, and Ac-Di-Sol, a rapid increase in available surface area and a large increase in maximum available surface area (Smax) were observed due to high swellability and wicking, even when the disintegrant concentration was only 1.0%. In contrast, for Kollidon CL and LH-21, a gradual increase in available surface area was observed, depending on the disintegrant concentration. To evaluate the disintegrant ability, Δtmax and ΔSmax were calculated by subtracting peak time (tmax) at 5.0% from that at 1.0% and subtracting Smax at 1.0% from that at 5.0%, respectively, and it was found that the water absorption ratio had strong negative correlations with Δtmax and ΔSmax. Therefore, this study demonstrates that analysis of only available surface area and parameters thereby obtained can directly provide useful information, especially about the disintegration ability of disintegrants. Copyright © 2013 Elsevier B.V. All rights reserved.

Marginally trapped surfaces and AdS/CFT

NASA Astrophysics Data System (ADS)

Grado-White, Brianna; Marolf, Donald

2018-02-01

It has been proposed that the areas of marginally trapped or anti-trapped surfaces (also known as leaves of holographic screens) may encode some notion of entropy. To connect this to AdS/CFT, we study the case of marginally trapped surfaces anchored to an AdS boundary. We establish that such boundary-anchored leaves lie between the causal and extremal surfaces defined by the anchor and that they have area bounded below by that of the minimal extremal surface. This suggests that the area of any leaf represents a coarse-grained von Neumann entropy for the associated region of the dual CFT. We further demonstrate that the leading area-divergence of a boundary-anchored marginally trapped surface agrees with that for the associated extremal surface, though subleading divergences generally differ. Finally, we generalize an argument of Bousso and Engelhardt to show that holographic screens with all leaves anchored to the same boundary set have leaf-areas that increase monotonically along the screen, and we describe a construction through which this monotonicity can take the more standard form of requiring entropy to increase with boundary time. This construction is related to what one might call future causal holographic information, which in such cases also provides an upper bound on the area of the associated leaves.

A Quantitative Approach to Determining the Ideal Female Lip Aesthetic and Its Effect on Facial Attractiveness.

PubMed

Popenko, Natalie A; Tripathi, Prem B; Devcic, Zlatko; Karimi, Koohyar; Osann, Kathryn; Wong, Brian J F

2017-07-01

Aesthetic proportions of the lips and their effect on facial attractiveness are poorly defined. Established guidelines would aid practitioners in achieving optimal aesthetic outcomes during cosmetic augmentation. To assess the most attractive lip dimensions of white women based on attractiveness ranking of surface area, ratio of upper to lower lip, and dimensions of the lip surface area relative to the lower third of the face. In phase 1 of this study, synthetic morph frontal digital images of the faces of 20 white women ages 18 to 25 years old were used to generate 5 varied lip surface areas for each face. These 100 faces were cardinally ranked by attractiveness through our developed conventional and internet-based focus groups by 150 participants. A summed ranking score of each face was plotted to quantify the most attractive surface area. In phase 2 of the study, 4 variants for each face were created with 15 of the most attractive images manipulating upper to lower lip ratios while maintaining the most attractive surface area from phase 1. A total of 60 faces were created, and each ratio was ranked by attractiveness by 428 participants (internet-based focus groups). In phase 3, the surface area from the most attractive faces was used to determine the total lip surface area relative to the lower facial third. Data were collected from March 1 to November 31, 2010, and analyzed from June 1 to October 31, 2016. Most attractive lip surface area, ratio of upper to lower lip, and dimension of the lips relative to the lower facial third. In phase 1, all 100 faces were cardinally ranked by 150 individuals (internet-based focus groups [n = 130] and raters from conventional focus groups [conventional raters] [n = 20]). In phase 2, all 60 faces were cardinally ranked by 428 participants (internet-based focus groups [n = 408] and conventional raters [n = 20]). The surface area that corresponded to the range of 2.0 to 2.5 × 104 pixels represented the highest summed rank, generating a pool of 14 images. This surface area was determined to be the most attractive and corresponded to a 53.5% increase in surface area from the original image. With the highest mean and highest proportions of most attractive rankings, the 1:2 ratio was deemed most attractive. Conversely, the ratio of 2:1 was deemed least attractive, having the lowest mean at 1.61 and the highest proportion of ranks within 1 with 310 votes (72.3%). Using a robust sample size, this study found that the most attractive lip surface area represents a 53.5% increase from baseline, an upper to lower lip ratio of 1:2, and a surface area equal to 9.6% of the lower third of the face. Lip dimensions and ratios derived in this study may provide guidelines in improving overall facial aesthetics and have clinical relevance to the field of facial plastic surgery. NA.

Evaluation of accessible mineral surface areas for improved prediction of mineral reaction rates in porous media

NASA Astrophysics Data System (ADS)

Beckingham, Lauren E.; Steefel, Carl I.; Swift, Alexander M.; Voltolini, Marco; Yang, Li; Anovitz, Lawrence M.; Sheets, Julia M.; Cole, David R.; Kneafsey, Timothy J.; Mitnick, Elizabeth H.; Zhang, Shuo; Landrot, Gautier; Ajo-Franklin, Jonathan B.; DePaolo, Donald J.; Mito, Saeko; Xue, Ziqiu

2017-05-01

The rates of mineral dissolution reactions in porous media are difficult to predict, in part because of a lack of understanding of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area used in reactive transport models for porous media are typically ad hoc and often based on average grain size, increased to account for surface roughness or decreased by several orders of magnitude to account for reduced surface reactivity of field as opposed to laboratory samples. In this study, accessible mineral surface areas are determined for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan) using a multi-scale image analysis based on synchrotron X-ray microCT, SEM QEMSCAN, XRD, SANS, and FIB-SEM. This analysis not only accounts for accessibility of mineral surfaces to macro-pores, but also accessibility through connected micro-pores in smectite, the most abundant clay mineral in this sample. While the imaging analysis reveals that most of the micro- and macro-pores are well connected, some pore regions are unconnected and thus inaccessible to fluid flow and diffusion. To evaluate whether mineral accessible surface area accurately reflects reactive surface area a flow-through core experiment is performed and modeled at the continuum scale. The core experiment is performed under conditions replicating the pilot site and the evolution of effluent solutes in the aqueous phase is tracked. Various reactive surface area models are evaluated for their ability to capture the observed effluent chemistry, beginning with parameter values determined as a best fit to a disaggregated sediment experiment (Beckingham et al., 2016) described previously. Simulations that assume that all mineral surfaces are accessible (as in the disaggregated sediment experiment) over-predict the observed mineral reaction rates, suggesting that a reduction of RSA by a factor of 10-20 is required to match the core flood experimental data. While the fit of the effluent chemistry (and inferred mineral dissolution rates) greatly improve when the pore-accessible mineral surface areas are used, it was also necessary to include highly reactive glass phases to match the experimental observations, in agreement with conclusions from the disaggregated sediment experiment. It is hypothesized here that the 10-20 reduction in reactive surface areas based on the limited pore accessibility of reactive phases in core flood experiment may be reasonable for poorly sorted and cemented sediments like those at the Nagaoka site, although this reflects pore rather than larger scale heterogeneity.

Tribological properties of surfaces

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1978-01-01

The real area of contact between two solid surfaces is only a small portion of the apparent area. Deformation of these areas can result in solid state contact through surface films. For clean solid to solid contact strong adhesive bonding occurs across the interface. Under these conditions many properties of the solid such as the metallurgical and chemical nature of metals can influence adhesion, friction, and wear behavior. The presence of gases, liquids, and solid films on the surface of solids alter markedly tribological characteristics. These surface films can also considerably change the mechanical effects of solid state contact on bulk material behavior.

Effect of a Facial Muscle Exercise Device on Facial Rejuvenation

PubMed Central

Hwang, Ui-jae; Kwon, Oh-yun; Jung, Sung-hoon; Ahn, Sun-hee; Gwak, Gyeong-tae

2018-01-01

Abstract Background The efficacy of facial muscle exercises (FMEs) for facial rejuvenation is controversial. In the majority of previous studies, nonquantitative assessment tools were used to assess the benefits of FMEs. Objectives This study examined the effectiveness of FMEs using a Pao (MTG, Nagoya, Japan) device to quantify facial rejuvenation. Methods Fifty females were asked to perform FMEs using a Pao device for 30 seconds twice a day for 8 weeks. Facial muscle thickness and cross-sectional area were measured sonographically. Facial surface distance, surface area, and volumes were determined using a laser scanning system before and after FME. Facial muscle thickness, cross-sectional area, midfacial surface distances, jawline surface distance, and lower facial surface area and volume were compared bilaterally before and after FME using a paired Student t test. Results The cross-sectional areas of the zygomaticus major and digastric muscles increased significantly (right: P < 0.001, left: P = 0.015), while the midfacial surface distances in the middle (right: P = 0.005, left: P = 0.047) and lower (right: P = 0.028, left: P = 0.019) planes as well as the jawline surface distances (right: P = 0.004, left: P = 0.003) decreased significantly after FME using the Pao device. The lower facial surface areas (right: P = 0.005, left: P = 0.006) and volumes (right: P = 0.001, left: P = 0.002) were also significantly reduced after FME using the Pao device. Conclusions FME using the Pao device can increase facial muscle thickness and cross-sectional area, thus contributing to facial rejuvenation. Level of Evidence: 4 PMID:29365050

Automated mapping of impervious surfaces in urban and suburban areas: Linear spectral unmixing of high spatial resolution imagery

NASA Astrophysics Data System (ADS)

Yang, Jian; He, Yuhong

2017-02-01

Quantifying impervious surfaces in urban and suburban areas is a key step toward a sustainable urban planning and management strategy. With the availability of fine-scale remote sensing imagery, automated mapping of impervious surfaces has attracted growing attention. However, the vast majority of existing studies have selected pixel-based and object-based methods for impervious surface mapping, with few adopting sub-pixel analysis of high spatial resolution imagery. This research makes use of a vegetation-bright impervious-dark impervious linear spectral mixture model to characterize urban and suburban surface components. A WorldView-3 image acquired on May 9th, 2015 is analyzed for its potential in automated unmixing of meaningful surface materials for two urban subsets and one suburban subset in Toronto, ON, Canada. Given the wide distribution of shadows in urban areas, the linear spectral unmixing is implemented in non-shadowed and shadowed areas separately for the two urban subsets. The results indicate that the accuracy of impervious surface mapping in suburban areas reaches up to 86.99%, much higher than the accuracies in urban areas (80.03% and 79.67%). Despite its merits in mapping accuracy and automation, the application of our proposed vegetation-bright impervious-dark impervious model to map impervious surfaces is limited due to the absence of soil component. To further extend the operational transferability of our proposed method, especially for the areas where plenty of bare soils exist during urbanization or reclamation, it is still of great necessity to mask out bare soils by automated classification prior to the implementation of linear spectral unmixing.

Electrocatalytically Active Nickel-Based Electrode Coatings Formed by Atmospheric and Suspension Plasma Spraying

NASA Astrophysics Data System (ADS)

Aghasibeig, M.; Mousavi, M.; Ben Ettouill, F.; Moreau, C.; Wuthrich, R.; Dolatabadi, A.

2014-01-01

Ni-based electrode coatings with enhanced surface areas, for hydrogen production, were developed using atmospheric plasma spray (APS) and suspension plasma spray (SPS) processes. The results revealed a larger electrochemical active surface area for the coatings produced by SPS compared to those produced by APS process. SEM micrographs showed that the surface microstructure of the sample with the largest surface area was composed of a large number of small cauliflower-like aggregates with an average diameter of 10 μm.

Explosively activated egress area

NASA Technical Reports Server (NTRS)

Bement, L. J.; Bailey, J. W. (Inventor)

1983-01-01

A lightweight, add on structure which employs linear shaped pyrotechnic charges to smoothly cut an airframe along an egress area periphery is provided. It compromises reaction surfaces attached to the exterior surface of the airframe's skin and is designed to restrict the skin deflection. That portion of the airframe within the egress area periphery is jettisoned. Retention surfaces and sealing walls are attached to the interior surface of the airframe's skin and are designed to shield the interior of the aircraft during detonation of the pyrotechnic charges.

Shapes of embedded minimal surfaces

PubMed Central

Colding, Tobias H.; Minicozzi, William P.

2006-01-01

Surfaces that locally minimize area have been extensively used to model physical phenomena, including soap films, black holes, compound polymers, protein folding, etc. The mathematical field dates to the 1740s but has recently become an area of intense mathematical and scientific study, specifically in the areas of molecular engineering, materials science, and nanotechnology because of their many anticipated applications. In this work, we show that all minimal surfaces are built out of pieces of the surfaces in Figs. 1 and 2. PMID:16847265

The spatial-temporal dynamics of open surface water bodies in CONUS during 1984-2016

NASA Astrophysics Data System (ADS)

Zou, Z.; Xiao, X.; Dong, J.; Qin, Y.; Doughty, R.; Menarguez, M.; Wang, J.

2017-12-01

Open surface water bodies provided 80% of the total water withdrawals in the Contiguous United States (CONUS) in 1985-2010. The inter-annual variability and changing trends of surface water body areas have various impacts on the human society and ecosystems. This study made use of all Landsat 5, 7, and 8 surface reflectance archives ( 370,000 images) during 1984-2016 and a water index- and pixel-based approach to detect and map open surface water bodies in the cloud-based platform of Google Earth Engine. The year-long water body area and annual average water body area were calculated for each of the last 33 years and their inter-annual variations during 1984-2016 were analyzed through anomaly analysis while their changing trends were analyzed through linear regressions. The national annual average water body areas varied from 265,000 to 281,000 km2 during 1984-2016, which is 3% below to 3% above the mean value 274,000 km2. In state level, significant decreasing trends were found in both year-long and annual average water body areas in some states of dry climates in west and southwest U.S., including Oregon, Nevada, Utah, Arizona, New Mexico, and Oklahoma. In comparison, significant increasing trends were found in some states of wet climates in the southeast and north U.S., including Indiana, Ohio, New Jersey, Delaware, Virginia, Tennessee, North Carolina, South Carolina, Louisiana, Alabama, Georgia, North Dakota and South Dakota. Open surface water body areas in CONUS decreased in relatively dry areas but increased in relatively wet areas. The relationships between open surface water body area variability and climate factors (precipitation, temperature) and human impacts (water exploitation) were also analyzed.

Digital retrospective motion-mode display and processing of electron beam cine-computed tomography and other cross-sectional cardiac imaging techniques

NASA Astrophysics Data System (ADS)

Reed, Judd E.; Rumberger, John A.; Buithieu, Jean; Behrenbeck, Thomas; Breen, Jerome F.; Sheedy, Patrick F., II

1995-05-01

Electron beam computed tomography is unparalleled in its ability to consistently produce high quality dynamic images of the human heart. Its use in quantification of left ventricular dynamics is well established in both clinical and research applications. However, the image analysis tools supplied with the scanners offer a limited number of analysis options. They are based on embedded computer systems which have not been significantly upgraded since the scanner was introduced over a decade ago in spite of the explosive improvements in available computer power which have occured during this period. To address these shortcomings, a workstation-based ventricular analysis system has been developed at our institution. This system, which has been in use for over five years, is based on current workstation technology and therefore has benefited from the periodic upgrades in processor performance available to these systems. The dynamic image segmentation component of this system is an interactively supervised, semi-automatic surface identification and tracking system. It characterizes the endocardial and epicardial surfaces of the left ventricle as two concentric 4D hyper-space polyhedrons. Each of these polyhedrons have nearly ten thousand vertices which are deposited into a relational database. The right ventricle is also processed in a similar manner. This database is queried by other custom components which extract ventricular function parameters such as regional ejection fraction and wall stress. The interactive tool which supervises dynamic image segmentation has been enhanced with a temporal domain display. The operator interactively chooses the spatial location of the endpoints of a line segment while the corresponding space/time image is displayed. These images, with content resembling M-Mode echocardiography, benefit form electron beam computed tomography's high spatial and contrast resolution. The segmented surfaces are displayed along with the imagery. These displays give the operator valuable feedback pertaining to the contiguity of the extracted surfaces. As with M-Mode echocardiography, the velocity of moving structures can be easily visualized and measured. However, many views inaccessible to standard transthoracic echocardiography are easily generated. These features have augmented the interpretability of cine electron beam computed tomography and have prompted the recent cloning of this system into an 'omni-directional M-Mode display' system for use in digital post-processing of echocardiographic parasternal short axis tomograms. This enhances the functional assessment in orthogonal views of the left ventricle, accounting for shape changes particularly in the asymmetric post-infarction ventricle. Conclusions: A new tool has been developed for analysis and visualization of cine electron beam computed tomography. It has been found to be very useful in verifying the consistency of myocardial surface definition with a semi-automated segmentation tool. By drawing on M-Mode echocardiography experience, electron beam tomography's interpretability has been enhanced. Use of this feature, in conjunction with the existing image processing tools, will enhance the presentations of data on regional systolic and diastolic functions to clinicians in a format that is familiar to most cardiologists. Additionally, this tool reinforces the advantages of electron beam tomography as a single imaging modality for the assessment of left and right ventricular size, shape, and regional functions.

33 CFR 334.1180 - Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. 334.1180 Section 334.1180 Navigation and Navigable... REGULATIONS § 334.1180 Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. (a) The...

33 CFR 334.1180 - Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. 334.1180 Section 334.1180 Navigation and Navigable... REGULATIONS § 334.1180 Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. (a) The...

33 CFR 334.1180 - Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. 334.1180 Section 334.1180 Navigation and Navigable... REGULATIONS § 334.1180 Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. (a) The...

33 CFR 334.1180 - Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. 334.1180 Section 334.1180 Navigation and Navigable... REGULATIONS § 334.1180 Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. (a) The...

33 CFR 334.1180 - Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. 334.1180 Section 334.1180 Navigation and Navigable... REGULATIONS § 334.1180 Strait of Juan de Fuca, Wash.; air-to-surface weapon range, restricted area. (a) The...

Potentiometric surface of the upper Patapsco Aquifer in southern Maryland, September 1991

USGS Publications Warehouse

Curtin, Stephen E.; Andreasen, D.C.; Mack, Frederick K.

1993-01-01

A map showing the potentiometric surface of the upper Patapsco aquifer in the Patapsco Formation of Cretaceous age in southern Maryland during September 1991 was prepared from water levels measured in wells. The potentiometric surface was at least 70 feet above sea level near the northwestern boundary and outcrop area of the aquifer in a topographically high area of Anne Arundel County, and at least 56 feet above sea level in a similar setting in Prince Georges County. From these high areas, the potentiometric surface declined to the south and southeast toward large well fields in the Annapolis and Waldorf areas and at the Chalk Point powerplant.

Nanosilver particle formation on a high surface area titanate.

PubMed

Shi, Meng; Lin, Christopher C H; Wu, Lan; Holt, Christopher M B; Mitlin, David; Kuznicki, Steven M

2010-12-01

Titanium based molecular sieves, such as ETS-10, have the ability to exchange silver ions and subsequently support self assembly of stable silver nanoparticles when heated. We report that a high surface area sodium titanate (resembling ETS-2) displays a similar ability to self template silver nanoparticles on its surface. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show high concentrations of silver nanoparticles on the surface of this sodium titanate, formed by thermal reduction of exchanged silver cations. The nanoparticles range in size from 4 to 12 nm, centered at around 6 nm. In addition to SEM and TEM, XRD and surface area analysis were used to characterize the material. The results indicate that this sodium titanate has a high surface area (>263 m2/g), and high ion exchange capacity for silver (30+ wt%) making it an excellent substrate for the exchange and generation of uniform, high-density silver nanoparticles.

Porous silicon structures with high surface area/specific pore size

DOEpatents

Northrup, M.A.; Yu, C.M.; Raley, N.F.

1999-03-16

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gases in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters. 9 figs.

Porous silicon structures with high surface area/specific pore size

DOEpatents

Northrup, M. Allen; Yu, Conrad M.; Raley, Norman F.

1999-01-01

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.

LANDSAT Remote Sensing: Observations of an Appalachian mountaintop surface coal mining and reclamation operation. [kentucky

NASA Technical Reports Server (NTRS)

1979-01-01

The potential benefits of using LANDSAT remote sensing data by state agencies as an aide in monitoring surface coal mining operations are reviewed. A mountaintop surface mine in eastern Kentucky was surveyed over a 5 year period using satellite multispectral scanner data that were classified by computer analyses. The analyses were guided by aerial photography and by ground surveys of the surface mines procured in 1976. The application of the LANDSAT data indicates that: (1) computer classification of the various landcover categories provides information for monitoring the progress of surface mining and reclamation operations; (2) successive yearly changes in barren and revegetated areas can be qualitatively assessed for surface mines of 100 acres or more of disrupted area; (3) barren areas consisting of limestone and shale mixtures may be recognized, and revegetated areas in various stages of growth may be identified against the hilly forest background.

LANDSAT remote sensing: observations of an Appalachian mountaintop surface coal mining and reclamation operation

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

Not Available

1979-10-01

The potential benefits of using LANDSAT remote sensing data by state agencies as an aide in monitoring surface coal mining operations are reviewed. A mountaintop surface mine in eastern Kentucky was surveyed over a 5 year period using satellite multispectral scanner data that were classified by computer analyses. The analyses were guided by aerial photography and by ground surveys of the surface mines procured in 1976. The application of the LANDSAT data indicates that: (1) computer classification of the various landcover categories provides information for monitoring the progress of surface mining and reclamation operations, (2) successive yearly changes in barrenmore » and revegetated areas can be qualitatively assessed for surface mines of 100 acres or more of disrupted area, (3) barren areas consisting of limestone and shale mixtures may be recognized, and revegetated areas in various stages of growth may be identified against the hilly forest background.« less

Evaluation of the Biological Sampling Kit (BiSKit) for Large-Area Surface Sampling

PubMed Central

Buttner, Mark P.; Cruz, Patricia; Stetzenbach, Linda D.; Klima-Comba, Amy K.; Stevens, Vanessa L.; Emanuel, Peter A.

2004-01-01

Current surface sampling methods for microbial contaminants are designed to sample small areas and utilize culture analysis. The total number of microbes recovered is low because a small area is sampled, making detection of a potential pathogen more difficult. Furthermore, sampling of small areas requires a greater number of samples to be collected, which delays the reporting of results, taxes laboratory resources and staffing, and increases analysis costs. A new biological surface sampling method, the Biological Sampling Kit (BiSKit), designed to sample large areas and to be compatible with testing with a variety of technologies, including PCR and immunoassay, was evaluated and compared to other surface sampling strategies. In experimental room trials, wood laminate and metal surfaces were contaminated by aerosolization of Bacillus atrophaeus spores, a simulant for Bacillus anthracis, into the room, followed by settling of the spores onto the test surfaces. The surfaces were sampled with the BiSKit, a cotton-based swab, and a foam-based swab. Samples were analyzed by culturing, quantitative PCR, and immunological assays. The results showed that the large surface area (1 m2) sampled with the BiSKit resulted in concentrations of B. atrophaeus in samples that were up to 10-fold higher than the concentrations obtained with the other methods tested. A comparison of wet and dry sampling with the BiSKit indicated that dry sampling was more efficient (efficiency, 18.4%) than wet sampling (efficiency, 11.3%). The sensitivities of detection of B. atrophaeus on metal surfaces were 42 ± 5.8 CFU/m2 for wet sampling and 100.5 ± 10.2 CFU/m2 for dry sampling. These results demonstrate that the use of a sampling device capable of sampling larger areas results in higher sensitivity than that obtained with currently available methods and has the advantage of sampling larger areas, thus requiring collection of fewer samples per site. PMID:15574898

New Technology-Large-Area Three- Dimensional Surface Profiling Using Only Focused Air-Coupled Ultrasound-Given 1999 R&D 100 Award

NASA Technical Reports Server (NTRS)

Roth, Don J.; Kautz, Harold E.; Abel, Phillip B.; Whalen, Mike F.; Hendricks, J. Lynne; Bodis, James R.

2000-01-01

Surface topography, which significantly affects the performance of many industrial components, is normally measured with diamond-tip profilometry over small areas or with optical scattering methods over larger areas. To develop air-coupled surface profilometry, the NASA Glenn Research Center at Lewis Field initiated a Space Act Agreement with Sonix, Inc., through two Glenn programs, the Advanced High Temperature Engine Materials Program (HITEMP) and COMMTECH. The work resulted in quantitative surface topography profiles obtained using only high-frequency, focused ultrasonic pulses in air. The method is nondestructive, noninvasive, and noncontact, and it does not require light-reflective surfaces. Air surface profiling may be desirable when diamond-tip or laserbased methods are impractical, such as over large areas, when a significant depth range is required, or for curved surfaces. When the configuration is optimized, the method is reasonably rapid and all the quantitative analysis facilities are online, including two- and three-dimensional visualization, extreme value filtering (for faulty data), and leveling.

Geohydrology and susceptibility of major aquifers to surface contamination in Alabama, area 7

USGS Publications Warehouse

Mooty, W.S.

1987-01-01

The geohydrology and susceptibility of the seven major aquifers to surface contamination in Area 7 - Bibb, Dallas, Hale, Perry, and Wilcox Counties, are described. Aquifers in the northern part of the study area are in Paleozoic limestones and dolomite formations. Deposits in the central part of the study area are predominately of Cretaceous age and contain the Coker, Gordo, and Eutaw aquifers. Although the southern part of the study area has many deposits of Tertiary age, the Ripley Formation of Cretaceous age is the major aquifer. Contamination of any of the major aquifers is improbable because the majority of the recharge area for the primary aquifers is woodland, pasture, or farmland. Downdip from their outcrops, the major aquifers in the study area are protected from land surface contamination by relatively impermeable layers of clay and chalk. The aquifers that are highly susceptible to contamination are the ones in the limestone and dolomite formations in northern Bibb County. Sinkholes exist in the recharge area of these formations and could provide a direct link for contaminates from the land surface to the water table. An area northeast of the Selma well field is also highly susceptible to contamination. The Eutaw Formation in this area is overlain by alluvial deposits that could increase recharge to the aquifer by slowing the runoff rate of surface water. (USGS)

Effect of wrinkles on the surface area of graphene: toward the design of nanoelectronics.

PubMed

Qin, Zhao; Taylor, Michael; Hwang, Mary; Bertoldi, Katia; Buehler, Markus J

2014-11-12

Graphene has attracted intense attention to the use in extreme applications. However, its small thickness facilitates wrinkle formation, and it is not clear how such structural change affects its area-specific capacitance. Herein, we combine molecular dynamics and continuum mechanics-based simulations to study the changes in surface area induced by wrinkles. We find that the high specific surface area of graphene can only be affected up to 2% regardless of loading conditions, geometry, and defects.

Geologic Surface Effects of Underground Nuclear Testing, Buckboard Mesa, Climax Stock, Dome Mountain, Frenchman Flat, Rainier/Aqueduct Mesa, and Shoshone Mountain, Nevada Test Site, Nevada

USGS Publications Warehouse

Grasso, Dennis N.

2003-01-01

Surface effects maps were produced for 72 of 89 underground detonations conducted at the Frenchman Flat, Rainier Mesa and Aqueduct Mesa, Climax Stock, Shoshone Mountain, Buckboard Mesa, and Dome Mountain testing areas of the Nevada Test Site between August 10, 1957 (Saturn detonation, Area 12) and September 18, 1992 (Hunters Trophy detonation, Area 12). The ?Other Areas? Surface Effects Map Database, which was used to construct the maps shown in this report, contains digital reproductions of these original maps. The database is provided in both ArcGIS (v. 8.2) geodatabase format and ArcView (v. 3.2) shapefile format. This database contains sinks, cracks, faults, and other surface effects having a combined (cumulative) length of 136.38 km (84.74 mi). In GIS digital format, the user can view all surface effects maps simultaneously, select and view the surface effects of one or more sites of interest, or view specific surface effects by area or site. Three map layers comprise the database. They are: (1) the surface effects maps layer (oase_n27f), (2) the bar symbols layer (oase_bar_n27f), and (3) the ball symbols layer (oase_ball_n27f). Additionally, an annotation layer, named 'Ball_and_Bar_Labels,' and a polygon features layer, named 'Area12_features_poly_n27f,' are contained in the geodatabase version of the database. The annotation layer automatically labels all 295 ball-and-bar symbols shown on these maps. The polygon features layer displays areas of ground disturbances, such as rock spall and disturbed ground caused by the detonations. Shapefile versions of the polygon features layer in Nevada State Plane and Universal Transverse Mercator projections, named 'area12_features_poly_n27f.shp' and 'area12_features_poly_u83m.shp,' are also provided in the archive.

Adsorption and photocatalytic degradation of methylene blue using high surface area titanate nanotubes (TNT) synthesized via hydrothermal method

NASA Astrophysics Data System (ADS)

Subramaniam, M. N.; Goh, P. S.; Abdullah, N.; Lau, W. J.; Ng, B. C.; Ismail, A. F.

2017-06-01

Removal of methylene blue (MB) via adsorption and photocatalysis using titanate nanotubes (TNTs) with different surface areas were investigated and compared to commercial titanium dioxide (TiO2) P25 Degussa nanoparticles. The TNTs with surface area ranging from 20 m2/g to 200 m2/g were synthesized via hydrothermal method with different reaction times. TEM imaging confirmed the tubular structure of TNT while XRD spectra indicated all TNTs exhibited anatase crystallinity. Batch adsorption rate showed linearity with surface properties of TNTs, where materials with higher surface area showed higher adsorption rate. The highest MB adsorption (70%) was achieved by TNT24 in 60 min whereas commercial TiO2 exhibited the lowest adsorption of only 10% after 240 min. Adsorption isotherm studies indicated that adsorption using TNT is better fitted into Langmuir adsorption isotherm than Freundlich isotherm model. Furthermore, TNT24 was able to perform up to 90% removal of MB within 120 min, demonstrating performance that is 2-fold better compared to commercial TiO2. The high surface area and surface Bronsted acidity are the main reasons for the improvement in MB removal performance exhibited by TNT24. The improvement in surface acidity enhanced the adsorption properties of all the nanotubes prepared in this study.

Cooling effect of rivers on metropolitan Taipei using remote sensing.

PubMed

Chen, Yen-Chang; Tan, Chih-Hung; Wei, Chiang; Su, Zi-Wen

2014-01-23

This study applied remote sensing technology to analyze how rivers in the urban environment affect the surface temperature of their ambient areas. While surface meteorological stations can supply accurate data points in the city, remote sensing can provide such data in a two-dimensional (2-D) manner. The goal of this paper is to apply the remote sensing technique to further our understanding of the relationship between the surface temperature and rivers in urban areas. The 2-D surface temperature data was retrieved from Landsat-7 thermal infrared images, while data collected by Formosat-2 was used to categorize the land uses in the urban area. The land surface temperature distribution is simulated by a sigmoid function with nonlinear regression analysis. Combining the aforementioned data, the range of effect on the surface temperature from rivers can be derived. With the remote sensing data collected for the Taipei Metropolitan area, factors affecting the surface temperature were explored. It indicated that the effect on the developed area was less significant than on the ambient nature zone; moreover, the size of the buffer zone between the river and city, such as the wetlands or flood plain, was found to correlate with the affected distance of the river surface temperature.

Cooling Effect of Rivers on Metropolitan Taipei Using Remote Sensing

PubMed Central

Chen, Yen-Chang; Tan, Chih-Hung; Wei, Chiang; Su, Zi-Wen

2014-01-01

This study applied remote sensing technology to analyze how rivers in the urban environment affect the surface temperature of their ambient areas. While surface meteorological stations can supply accurate data points in the city, remote sensing can provide such data in a two-dimensional (2-D) manner. The goal of this paper is to apply the remote sensing technique to further our understanding of the relationship between the surface temperature and rivers in urban areas. The 2-D surface temperature data was retrieved from Landsat-7 thermal infrared images, while data collected by Formosat-2 was used to categorize the land uses in the urban area. The land surface temperature distribution is simulated by a sigmoid function with nonlinear regression analysis. Combining the aforementioned data, the range of effect on the surface temperature from rivers can be derived. With the remote sensing data collected for the Taipei Metropolitan area, factors affecting the surface temperature were explored. It indicated that the effect on the developed area was less significant than on the ambient nature zone; moreover, the size of the buffer zone between the river and city, such as the wetlands or flood plain, was found to correlate with the affected distance of the river surface temperature. PMID:24464232

Ability of barrier coat S-PRG coating to arrest artificial enamel lesions in primary teeth.

PubMed

Hosoya, Yumiko; Ando, Susumu; Otani, Hideji; Yukinari, Tetsuhiro; Miyazaki, Masashi; Garcia-Godoy, Franklin

2013-10-01

To evaluate the effects of a surface pre-reacted glass-ionomer (S-PRG) filled coating material to arrest artificial enamel lesions in primary teeth. Buccal and lingual enamel was demineralized in 0.1 M lactic acid buffer solution (pH 4.75) for 5 days and then divided in the PRG-applied and non-PRG areas. Proximal surfaces were used as a control area without demineralization and coating application. Teeth were divided into three groups (n = 4) according to the 1-week immersion in different solutions: Group 1 (distilled water), Group 2 (demineralizing solution) and Group 3 (artificial saliva). Hardness and Young's modulus by nano-indentation test, and elemental contents and ultrastructure by SEM/EDX analysis were obtained. Data were statistically analyzed using ANOVA and Fisher's PLSD at alpha = 0.05. Only for the non-PRG area in Group 1, the hardness and Young's modulus of the demineralized surface enamel were significantly lower than those of the enamel 30-60 microm beneath the surface. Demineralized enamel of non-PRG and PRG-applied areas showed similar SEM views. Only for the non-PRG area in Group 2 and control area in Group 3, the Ca/P of the surface enamel was significantly higher than that of the enamel 5-10 microm beneath the surface. There was no significant difference of the Ca/P among the measuring points from the surface to 10 microm depth of enamel for the PRG applied area in Group 2.

30 CFR 933.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., forest, recreation area, or places; (f)(1) Where the proposed surface coal mining operation may adversely... mining by Act of Congress. 933.761 Section 933.761 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS...

30 CFR 933.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., forest, recreation area, or places; (f)(1) Where the proposed surface coal mining operation may adversely... mining by Act of Congress. 933.761 Section 933.761 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS...

30 CFR 933.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., forest, recreation area, or places; (f)(1) Where the proposed surface coal mining operation may adversely... mining by Act of Congress. 933.761 Section 933.761 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS...

30 CFR 933.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., forest, recreation area, or places; (f)(1) Where the proposed surface coal mining operation may adversely... mining by Act of Congress. 933.761 Section 933.761 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS...

Biochar characteristics produced from food-processing products and their sorptive capacity for mercury and phenanthrene

NASA Astrophysics Data System (ADS)

Fotopoulou, Kalliopi N.; Karapanagioti, Hrissi K.; Manariotis, Ioannis D.

2015-04-01

Various organic-rich wastes including wood chips, animal manure, and crop residues have been used for biochar production. Biochar is used as an additive to soils to sequester carbon and improve soil fertility but its use as a sorbent for environmental remediation processes is gaining increased attention. Surface properties such as point of zero charge, surface area and pore volume, surface topography, surface functional groups and acid-base behavior are important factors, which affect sorption efficiency. Understanding the surface alteration of biochars increases our understanding of the pollutant-sorbent interaction. The scope of the present work was to evaluate the effect of key characteristics of biochars on their sorptive properties. Raw materials for biochar production were evaluated including byproducts from brewering, coffee, wine, and olive oil industry. The charring process was performed at different temperatures under limited-oxygen conditions using specialized containers. The surface area, the pore volume, and the average pore size of the biochars were determined. Open surface area and micropore volume were determined using t-plot method and Harkins & Jura equation. Raw food-processing waste demonstrates low surface area that increases by 1 order of magnitude by thermal treatment up to 750oC. At temperatures from 750 up to 900oC, pyrolysis results to biochars with surface areas 210-700 m2/g. For the same temperature range, a high percentage (46 to73%) of the pore volume of the biochars is due to micropores. Positive results were obtained when high surface area biochars were tested for their ability to remove organic (i.e. phenanthrene) and inorganic (i.e. mercury) compounds from aqueous solutions. All these properties point to new materials that can effectively be used for environmental remediation.

Roles of surface water areas for water and solute cycle in Hanoi city, Viet Nam

NASA Astrophysics Data System (ADS)

Hayashi, Takeshi; Kuroda, Keisuke; Do Thuan, An; Tran Thi Viet, Nga; Takizawa, Satoshi

2013-04-01

Hanoi city, the capital of Viet Nam, has developed beside the Red river. Recent rapid urbanization of this city has reduced a large number of natural water areas such as lakes, ponds and canals not only in the central area but the suburban area. Contrary, the urbanization has increased artificial water areas such as pond for fish cultivation and landscaping. On the other hand, the urbanization has induced the inflow of waste water from households and various kinds of factories to these water areas because of delay of sewerage system development. Inflow of the waste water has induced eutrophication and pollution of these water areas. Also, there is a possibility of groundwater pollution by infiltration of polluted surface water. However, the role of these water areas for water cycle and solute transport is not clarified. Therefore, this study focuses on the interaction between surface water areas and groundwater in Hanoi city to evaluate appropriate land development and groundwater resource management. We are carrying out three approaches: a) understanding of geochemical characteristics of surface water and groundwater, b) monitoring of water levels of pond and groundwater, c) sampling of soil and pond sediment. Correlation between d18O and dD of precipitation (after GNIP), the Red River (after GNIR) and the water samples of this study showed that the groundwater is composed of precipitation, the Red River and surface water that has evaporation process. Contribution of the surface water with evaporation process was widely found in the study area. As for groundwater monitoring, the Holocene aquifers at two sites were in unconfined condition in dry season and the groundwater levels in the aquifer continued to increase through rainy season. The results of isotopic analysis and groundwater level monitoring showed that the surface water areas are one of the major groundwater sources. On the other hand, concentrations of dissolved Arsenic (filtered by 0.45um) in the pore water of the pond sediments were much higher than the pond water and closed to that of groundwater. Also, other metal elements showed the same trend. This result suggested that Arsenic and other metal elements recharged to these ponds is probably adsorbed and removed by sediments (including organic matters). That is, pond sediment plays an important role for solute transport as a filter of Arsenic and metal elements. The results of this study strongly suggest that the natural and artificial surface water areas have important roles for water cycle and solute transport in Hanoi city. Although the number of the natural water areas is decreasing, dredging of artificial water areas increases the infiltration from the surface to aquifers. Therefore, qualitative and quantitative preservation of the surface water areas is important for conservation of groundwater environment and contribute to sustainable groundwater management in Hanoi city.

30 CFR 77.1700 - Communications in work areas.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Communications in work areas. 77.1700 Section... AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Miscellaneous § 77.1700 Communications in work areas. No employee shall be assigned, or allowed...

30 CFR 77.1700 - Communications in work areas.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Communications in work areas. 77.1700 Section... AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Miscellaneous § 77.1700 Communications in work areas. No employee shall be assigned, or allowed...

Biochar from Coffee Residues: A New Promising Sorbent

NASA Astrophysics Data System (ADS)

Fotopoulou, Kalliopi; Karapanagioti, Hrissi; Manariotis, Ioannis

2014-05-01

Biochar is a carbon-rich material produced by heating biomass in an oxygen-limited environment. Biochar is mainly used as an additive to soils to sequester carbon and improve soil fertility as well as a sorbent for environmental remediation processes. Surface properties such as point of zero charge, surface area and pore volume, surface topography, surface functional groups and acid-base behavior are important factors, which affect sorption efficiency. Understanding the surface alteration of biochars increases our understanding of the pollutant-sorbent interaction. The objective of the present study was to characterize the surface properties of biochar produced, and to investigate the effect of thermal treatment conditions on key characteristics that affect sorptive properties. The espresso coffee residue was obtained after the coffee was brewed through espresso machines in coffee shops. The coffee residue was dried and kept in an oven at 50oC until its pyrolysis at 850oC. Pyrolysis with different coffee mass and containers were tested in order to find optimum biochar characteristics. Detailed characterization techniques were carried out to determine the properties of the produced biochar. The surface area, the pore volume, and the average pore size of the biochars were determined using gas (N2) adsorption-desorption cycles using the Brunauer, Emmett, and Teller (BET) equation. Open surface area and micropore volume were determined using the t-plot method and the Harkins & Jura equation. Total organic carbon was also determined because it is an important factor that affects sorption. The results were compared with the corresponding properties of activated carbons. The biochar produced exhibited a wide range of surface area from 21 to 770 m2/g and open surface area from 21 to 65 m2/g. It is obvious that the surface area results from the formation of pores. Actually it was calculated that up to 90% of the porosity is due to the micropores. More specifically the average size of the pores for the high surface area biochars was 32 A. Finally, the organic carbon content of the produced biochar ranged from 45 to 75%.

Mapping Hydrophobicity on the Protein Molecular Surface at Atom-Level Resolution

PubMed Central

Nicolau Jr., Dan V.; Paszek, Ewa; Fulga, Florin; Nicolau, Dan V.

2014-01-01

A precise representation of the spatial distribution of hydrophobicity, hydrophilicity and charges on the molecular surface of proteins is critical for the understanding of the interaction with small molecules and larger systems. The representation of hydrophobicity is rarely done at atom-level, as this property is generally assigned to residues. A new methodology for the derivation of atomic hydrophobicity from any amino acid-based hydrophobicity scale was used to derive 8 sets of atomic hydrophobicities, one of which was used to generate the molecular surfaces for 35 proteins with convex structures, 5 of which, i.e., lysozyme, ribonuclease, hemoglobin, albumin and IgG, have been analyzed in more detail. Sets of the molecular surfaces of the model proteins have been constructed using spherical probes with increasingly large radii, from 1.4 to 20 Å, followed by the quantification of (i) the surface hydrophobicity; (ii) their respective molecular surface areas, i.e., total, hydrophilic and hydrophobic area; and (iii) their relative densities, i.e., divided by the total molecular area; or specific densities, i.e., divided by property-specific area. Compared with the amino acid-based formalism, the atom-level description reveals molecular surfaces which (i) present an approximately two times more hydrophilic areas; with (ii) less extended, but between 2 to 5 times more intense hydrophilic patches; and (iii) 3 to 20 times more extended hydrophobic areas. The hydrophobic areas are also approximately 2 times more hydrophobicity-intense. This, more pronounced “leopard skin”-like, design of the protein molecular surface has been confirmed by comparing the results for a restricted set of homologous proteins, i.e., hemoglobins diverging by only one residue (Trp37). These results suggest that the representation of hydrophobicity on the protein molecular surfaces at atom-level resolution, coupled with the probing of the molecular surface at different geometric resolutions, can capture processes that are otherwise obscured to the amino acid-based formalism. PMID:25462574

Relationship between surface area for adhesion and tensile bond strength--evaluation of a micro-tensile bond test.

PubMed

Sano, H; Shono, T; Sonoda, H; Takatsu, T; Ciucchi, B; Carvalho, R; Pashley, D H

1994-07-01

The purpose of this study was to test the null hypothesis that there is no relationship between the bonded surface area of dentin and the tensile strength of adhesive materials. The enamel was removed from the occlusal surface of extracted human third molars, and the entire flat surface was covered with resin composite bonded to the dentin to form a flat resin composite crown. Twenty-four hours later, the bonded specimens were sectioned parallel to the long axis of the tooth into 10-20 thin sections whose upper part was composed of resin composite with the lower half being dentin. These small sections were trimmed using a high speed diamond bur into an hourglass shape with the narrowest portion at the bonded interface. Surface area was varied by altering the specimen thickness and width. Tensile bond strength was measured using custom-made grips in a universal testing machine. Tensile bond strength was inversely related to bonded surface area. At surface areas below 0.4 mm2, the tensile bond strengths were about 55 MPa for Clearfil Liner Bond 2 (Kuraray Co., Ltd.), 38 MPa for Scotchbond MP (3M Dental Products), and 20 MPa for Vitremer (3M Dental Products). At these small surface areas all of the bond failures were adhesive in nature. This new method permits measurement of high bond strengths without cohesive failure of dentin. It also permits multiple measurements to be made within a single tooth.

Solar energy apparatus with apertured shield

NASA Technical Reports Server (NTRS)

Collings, Roger J. (Inventor); Bannon, David G. (Inventor)

1989-01-01

A protective apertured shield for use about an inlet to a solar apparatus which includesd a cavity receiver for absorbing concentrated solar energy. A rigid support truss assembly is fixed to the periphery of the inlet and projects radially inwardly therefrom to define a generally central aperture area through which solar radiation can pass into the cavity receiver. A non-structural, laminated blanket is spread over the rigid support truss in such a manner as to define an outer surface area and an inner surface area diverging radially outwardly from the central aperture area toward the periphery of the inlet. The outer surface area faces away from the inlet and the inner surface area faces toward the cavity receiver. The laminated blanket includes at least one layer of material, such as ceramic fiber fabric, having high infra-red emittance and low solar absorption properties, and another layer, such as metallic foil, of low infra-red emittance properties.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Chaffee County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Chaffee County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2o were considered ASTER modeled very warm surface exposures (thermal anomalies). Note: 'o' is used in this description to represent lowercase sigma.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Garfield County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Garfield County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1o and 2o were considered ASTER modeled warm surface exposures (thermal anomalies) Note: 'o' is used in this description to represent lowercase sigma.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Routt County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Routt County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1o and 2o were considered ASTER modeled warm surface exposures (thermal anomalies). Note: 'o' is used in this description to represent lowercase sigma.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Dolores County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Dolores County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2o were considered ASTER modeled very warm surface exposures (thermal anomalies) Note: 'o' is used in this description to represent lowercase sigma.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Archuleta County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Archuleta County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1o and 2o were considered ASTER modeled warm surface exposures (thermal anomalies). Note: 'o' is used in this description to represent lowercase sigma.

Influence of hydrophobic and superhydrophobic surfaces on reducing aerodynamic insect residues

NASA Astrophysics Data System (ADS)

Krishnan, K. Ghokulla; Milionis, Athanasios; Loth, Eric; Farrell, Thomas E.; Crouch, Jeffrey D.; Berry, Douglas H.

2017-01-01

Insect fouling during takeoff, climb and landing can result in increased drag and fuel consumption for aircrafts with laminar-flow surfaces. This study investigates the effectiveness of various hydrophobic and superhydrophobic surfaces in reducing residue of insects on an aerodynamic surface at relatively high impact speeds (about 45 m/s). An experimental setup consisting of a wind tunnel and a method to inject live flightless fruit flies was used to test the effectiveness of various surfaces against insect fouling. Insect fouling was analyzed based on residue area and height from multiple impacts. In general most of the residue area was due to the hemolymph spreading while most of the residue height was due to adhesion of exoskeleton parts. Hydrophobic and especially superhydrophobic surfaces performed better than a hydrophilic aluminum surface in terms of minimizing the residue area of various insect components (exoskeleton, hemolymph, and red fluid). Surfaces with reduced wettability and short lateral length scales tended to have the smallest residue area. Residue height was not as strongly influenced by surface wettability since even a single exoskeleton adhered to the surface upon impact was enough to produce a residue height of the order of one mm. In general, the results indicate that hemolymph spread needs to be avoided (e.g. by having reduced wettability and short lateral correlation lengths) in order to minimize the residue area, while exoskeleton adherence needs to be avoided (e.g. by having oleophobic properties and micro/nano roughness) in order to minimize the residue height. In particular, two of the superhydrophobic coatings produced substantial reduction in residue height and area, relative to the baseline surface of aluminum. However, the surfaces also showed poor mechanical durability on the high-speed insect impact location. This suggests that although low wettability materials show great insect anti-fouling behavior, their durability needs to be substantially improved in order to withstand harsh aerospace conditions.

33 CFR 334.200 - Chesapeake Bay, Point Lookout to Cedar Point; aerial and surface firing range and target area, U...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Cedar Point; aerial and surface firing range and target area, U.S. Naval Air Station, Patuxent River... Chesapeake Bay, Point Lookout to Cedar Point; aerial and surface firing range and target area, U.S. Naval Air Station, Patuxent River, Maryland, danger zones. (a) Aerial firing range—(1) The danger zone. The waters...

33 CFR 334.200 - Chesapeake Bay, Point Lookout to Cedar Point; aerial and surface firing range and target area, U...

Code of Federal Regulations, 2012 CFR

2012-07-01

... Cedar Point; aerial and surface firing range and target area, U.S. Naval Air Station, Patuxent River... Chesapeake Bay, Point Lookout to Cedar Point; aerial and surface firing range and target area, U.S. Naval Air Station, Patuxent River, Maryland, danger zones. (a) Aerial firing range—(1) The danger zone. The waters...

33 CFR 334.200 - Chesapeake Bay, Point Lookout to Cedar Point; aerial and surface firing range and target area, U...

Code of Federal Regulations, 2014 CFR

2014-07-01

... Cedar Point; aerial and surface firing range and target area, U.S. Naval Air Station, Patuxent River... Chesapeake Bay, Point Lookout to Cedar Point; aerial and surface firing range and target area, U.S. Naval Air Station, Patuxent River, Maryland, danger zones. (a) Aerial firing range—(1) The danger zone. The waters...