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David Schwartzman

Publications and source records attributed to David Schwartzman.

35 records · Page 2Linked to original sources
PubMed2003

Regional correlation by color-coded tissue Doppler to quantify improvements in mechanical left ventricular synchrony after biventricular pacing therapy.

Cardiac resynchronization therapy (CRT) can improve cardiac function in patients with heart failure and left bundle branch block. To test a new synchrony index derived from mitral annular velocity by color tissue Doppler, 19 subjects were studied: 9 patients with heart failure and left bundle branch block at baseline and at 1, 3 and 6 months after CRT and 10 normal controls. The synchrony index in patients with heart failure was less than that in controls at baseline (r = 0.60 +/- 0.13 vs 0.94 +/- 0.02; p <0.01), but improved at 6 months after CRT (r = 0.77 +/- 0.09; p <0.05 vs baseline).

Aged↗
PubMed2003

Characterization of left atrium and distal pulmonary vein morphology using multidimensional computed tomography.

OBJECTIVES: This study was designed to examine the dimensions and morphology of left atrial (LA) and distal pulmonary veins (PVs) using multidetector helical computed tomography (MDCT). BACKGROUND: Detailed knowledge of LA and PV anatomy will assist in the development of techniques for ablative intervention. Multidetector helical computed tomography is a method for multidimensional imaging of cardiac anatomy. METHODS: Multidetector helical computed tomography was used to image the LA and PVs in 70 subjects with and 47 subjects without atrial fibrillation (AF). Accuracy of the MDCT data was confirmed by correlation with echocardiography and endocardial electrogram recordings. RESULTS: Left atrial and PV dimensions were significantly larger in AF versus non-AF subjects, men versus women, and subjects with persistent versus paroxysmal AF. There were no differences between groups in morphologic detail. CONCLUSIONS: Multidetector helical computed tomography images of the LA and PVs are accurate and provide detailed anatomic information. Significant differences in dimensions but not morphologic detail were apparent between groups.

Adult↗
PubMed2003

Detecting instabilities of cardiac rhythm.

Diminished beat-to-beat variations in cardiac cycle lengths (CLs) are associated with poor prognosis after acute myocardial infarction and in patients with heart failure. Short-long-short sequences of cardiac cycles, or ultra-short rhythm instabilities, precede initiation of ventricular tachyarrhythmias in some patients. However, little is known about clinical or prognostic significance of abrupt short-term instabilities in CL (AICL) that occur minutes to hours before the event, in part because appropriate analytical methods are lacking. Although various techniques have been used to analyze CL changes, methods for analysis of AICL are limited. We compared performance of time domain, spectral, nonlinear, and pattern recognition techniques with respect to the detection and quantification of AICL. Because of high intra- and inter-subject variability of CL, pattern recognition techniques compared favorably to other studied methods. In continuous ambulatory ECG recordings, AICL occurred hours before spontaneous initiation of sustained atrial and ventricular arrhythmias in different patient populations. AICL were also found prior to the onset of spontaneous ventricular arrhythmias in a mouse model of congestive heart failure. To quantify AICL, we used the number of unstable orthogonal projection coefficients; this number gradually increased hours before the event. Removal of ectopic beats reduced but did not eliminate AICL. To illustrate potential physiological effects and temporal evolution of AICL, we used a simple, continuous, two-dimensional model of cardiac tissue governed by the Morris-Lecar equations. Computer simulations in this model showed that AICL may lead to gradual accumulation of spatial irregularities of the propagation wavefront giving rise to the initiation of reentry. Time-frequency analysis of the most significant eigenvectors of cardiac rhythm in subjects undergoing head-up tilt showed that AICL could indicate instabilities and unsuccessful adaptation of autonomic nervous system activity to physiological stimuli.

Animals↗
PubMed2003

A new device for beating heart bipolar radiofrequency atrial ablation.

OBJECTIVE: A technique for mimicking left atrial atriotomies using an ablation device that can be deployed without cardiopulmonary bypass has been developed. METHODS: In 12 healthy large (35-50 kg) adult pigs, maze-like ablation lesions were directly applied to the left atrial epicardium on the beating heart. The ablation device is irrigated, with a bipolar "hemostat" morphology, utilizing radiofrequency energy. Prior to and after ablation, left atrial electromechanical properties were measured during sinus rhythm in the latest 5 pigs using percutaneous endocardial catheter electromechanical mapping and intracardiac echocardiography. Pathologic analysis was performed acutely. RESULTS: All ablation lesions demonstrated conduction block along their entire course. Global left atrial conduction time (49.4 +/- 8.8 milliseconds before vs 58.8 +/- 9 milliseconds after) and pattern were not significantly altered. Although a significant amount (17.12% +/- 9%) of myocardium was either ablated or electrically isolated, ablation was not associated with significant alterations in global left atrial mechanics (left atrium ejection fraction 19% before vs 17% after; pulmonary vein peak flow velocity 1.22 m/s before vs 1.38 m/s after; peak mitral inflow velocity 2.34 m/s before vs 2.64 m/s after), mitral valve function, nor left ventricular function. There was no evidence of atrial thrombus formation. Transmurality was achieved in most lesions with no evidence of charring or barotrauma. CONCLUSIONS: Utilizing this ablation device, atrial lesions similar to the left component of the Maze procedure were deployed with uniform success in a beating heart without cardiopulmonary bypass or atriotomy and without adverse effects on left atrial electromechanics.

Animals↗
PubMed2003

Catheter ablation to suppress atrial fibrillation: evolution of technique at a single center.

BACKGROUND: Catheter ablation of atrial fibrillation is a rapidly evolving art. There is currently no consensus as to optimal methodology. We report a sequential experience, during which three distinct ablation techniques were utilized. METHODS: A cohort of 112 patients in whom atrial fibrillation onset was precipitated by ectopy arising solely from myocardium investing the pulmonary veins underwent catheter ablation using one of three techniques: focal (Group A); individual vein encircling (Group B); vestibule encircling (Group C). In each group, non-fluoroscopic guidance of the mapping and ablation process was provided by the tandem use of CARTO and intracardiac echocardiography. RESULTS: In all groups, endocardial topography was complex, and ablation electrode-endocardial contact was often unstable. Maximal electrode temperatures were low, despite frequent echocardiographic evidence of myocardial boiling. A significant progression in the number of radiofrequency energy applications between groups A and C was observed. Although acute suppression of atrial fibrillation inducibility was observed uniformly, chronic suppression rates were significantly different: Group A = 47%; Group B; 69%; Group C = 87%. CONCLUSIONS: In this non-concurrent cohort, the rate of chronic suppression of atrial fibrillation correlated with the amount of myocardium ablated or electrically isolated. Prospective data will be required to further evaluate whether "more is better."

Adult↗
PubMed2003

Site-selective atrial septal puncture.

Atrial transseptal puncture is a technique that provides pervenous access to the left heart. The aim of this technique is to provide catheter access to the left atrium and ventricle for mapping, as well as stable electrode-endocardial contact for ablation energy application. In the present report, "site-selective" atrial septal puncture is described and illustrated using case reports.

Adult↗
PubMed2003

Epicardium-based left atrial ablation: impact on electromechanical properties.

UNLABELLED: Epicardium-Based LA Ablation. INTRODUCTION: An important developmental task for surgical ablation of atrial fibrillation is simplification. A significant step would be the development of tools that create satisfactory ablation lesions without necessitating cardiopulmonary bypass or atriotomy. Optimally, these lesions would have no adverse impact on atrial electromechanical properties. METHODS AND RESULTS: We sought to characterize left atrial (LA) lesions created by a bipolar ablation device without cardiopulmonary bypass or atriotomy and to assess their impact on LA electromechanical properties. In each of five pigs, lesions were delivered to the epicardium of the beating heart, and encircled and connected right and left pulmonary vein vestibules and the atrial appendage. Before and after ablation, LA electromechanical properties were assessed using endocardial electromechanical mapping and intracardiac echocardiography. Postmortem histologic analysis also was performed. Each lesion was thrombus-free and barotrauma-free, histologically transmural, and a complete conduction barrier. Although a large aggregate area (24% +/- 6%) of LA myocardium was excluded, there was no significant change in global electromechanical properties. However, marked diminishment in appendage function was observed. CONCLUSION: Epicardium-based LA ablation in a beating heart could be achieved successfully without cardiopulmonary bypass or atriotomy. Although there was no adverse impact on global electromechanical properties, there was evidence of important regional diminishment.

Animals↗
PubMed2003

Left heart pacing lead implantation using subxiphoid videopericardioscopy.

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

Animals↗
PubMed2003

Multi-detector row CT of the left atrium and pulmonary veins before radio-frequency catheter ablation for atrial fibrillation.

Radio-frequency catheter ablation (RFCA) of the distal pulmonary veins and posterior left atrium is increasingly being used to treat recurrent or refractory atrial fibrillation that resists pharmacologic therapy or cardioversion. Successful RFCA of atrial fibrillation requires resolution of abnormal rhythms while minimizing complications and can be achieved with precise, preprocedural, three-dimensional (3D) anatomic delineation of the target, the atriopulmonary venous junction. Three-dimensional multi-detector row computed tomography (CT) of the pulmonary veins and left atrium provides the necessary anatomic information for successful RFCA, including (a) the number, location, and angulation of pulmonary veins and their ostial branches unobscured by adjacent cardiac and vascular anatomy, and (b) left atrial volume. The 3D multi-detector row CT scanning and postprocessing techniques used for pre-RFCA planning are straightforward. Radiologists must not only understand these techniques but must also be familiar with atrial fibrillation and the technical considerations and complications associated with RFCA of this condition. In addition, radiologists must be familiar with anatomic variants of the left atrium and distal pulmonary veins and understand the importance of these variants to the referring cardiac interventional electrophysiologist.

Atrial Fibrillation↗
PubMed2002

Early recurrence of atrial fibrillation after ambulatory shock conversion.

OBJECTIVES: We sought to gain insights into the early recurrence of atrial fibrillation (ERAF) after cardioversion shocks delivered by permanently implanted rhythm management systems. BACKGROUND: Several reports have characterized ERAF, but these reports used a limited definition and did not evaluate an association between clinical or device variables and ERAF. METHODS: A total of 144 patients with recurrent, drug-resistant, symptomatic atrial fibrillation (AF) underwent implantation of an atrial rhythm management system (Medtronic Jewel AF, Model 7250, Minneapolis, Minnesota). The device was programmed to deliver cardioversion shocks automatically and/or on patient command. The incidence of ERAF was evaluated after 1,092 successful shocks among 97 patients. Three different ERAF definitions were used: recurrence within 1 min, 1 h or 1 day. Multiple clinical and device variables were assessed for their relationship with ERAF. RESULTS: The per-patient incidences of ERAF were 44%, 61% and 70% for ERAF within 1 min, 1 h and 1 day, respectively. The per-episode incidences of ERAF were 17%, 30% and 43% for ERAF within 1 min, 1 h and 1 day, respectively. Variables that were independently associated with ERAF included AF duration <3 h before termination, more than one shock required to cardiovert and the absence of a previous myocardial infarction. The most potent variable was AF duration <3 h, associated with a threefold increase in the incidence of ERAF. CONCLUSIONS: Recurrence of AF early after ambulatory shock cardioversion is common. In this retrospective study, both clinical and device variables were predictive.

Atrial Fibrillation↗
PubMed2002

Determinants of first-shock success for atrial implantable cardioverter defibrillators.

INTRODUCTION: The aim of this study was to identify determinants of first-shock success for defibrillation of spontaneous atrial fibrillation (AF) in ambulatory patients with an atrial implantable cardioverter defibrillator (ICD). The determinants of first-shock success in ambulatory patients with atrial ICDs are unknown. METHODS AND RESULTS: We used the generalized estimating equation method to analyze determinants of first-shock success in 50 consecutive atrial ICD recipients in whom DFT+ (weakest shock that defibrillates on two consecutive trials) was determined at implant and spontaneous AF was shocked with shock strength > or = 2 x DFT+. DFT+ was 6.2 +/- 3.1 J. Of 470 first shocks, 407 were successful (generalized estimating equation 85%, confidence interval 79% to 90%). Determinants of first-shock success were use of coronary sinus electrode (univariate P = 0.02; multivariate P < 0.001, relative risk 5.0), absence of a Class III antiarrhythmic drug (univariate P = 0.06; multivariate P < 0.001, relative risk 3.2), absence of early recurrence of atrial fibrillation (ERAF; univariate P = 0.06; multivariate P = 0.02, relative risk 2.9), and longer duration of AF prior to shock > or = 3 hours (univariate: P = 0.02; multivariate P = NS). Sinus rhythm >1 minute persisted after 93% of first shocks in patients without documented ERAF but after only 58% of shocks in patients with documented ERAF (P < 0.001). CONCLUSION: Reducing ERAF is critical to achieving a clinically acceptable rate of persistent sinus rhythm after first shocks. For first shocks > or = 2 x DFT +, success is not increased by programming stronger shocks. Early cardioversion does not increase first-shock success.

Ambulatory Care↗
PubMed1998

Intracardiac Echocardiographic Imaging in Guiding and Monitoring Radiofrequency Catheter Ablation at the Tricuspid Annulus.

Intracardiac echocardiography (ICE) with lower frequency is a new imaging modality. We present the case of a patient with dilated cardiomyopathy and recurrent supraventricular tachycardia due to a right posterolateral accessory pathway. ICE imaging was performed using a 9-MHz (9-Fr) catheter positioned in the right atrium and guided precise catheter localization at the lateral tricuspid annulus where the bypass tract was located, which facilitated successful radiofrequency ablation. In addition, ICE imaging detected anatomic abnormalities, including localized pericardial effusion and torn tricuspid chordae tendineae, which were all identified at the onset of the procedure. The effusions remained stable during imaging monitoring throughout the procedure, which helped reassure us that these abnormalities were not procedure related. In summary, ICE imaging may significantly improve procedural efficacy in selected catheter ablation procedure and help detect anatomic abnormalities, procedural complications, or both.

Journal Article↗
PubMed1997

Multiplane Transesophageal and Intracardiac Echocardiography in Large Swine: Imaging Technique, Normal Values, and Research Applications.

Transthoracic echocardiographic imaging has been difficult to attain in the swine model. This study: (1) compares multiplane transesophageal echocardiography (TEE) with single plane TEE and intracardiac catheter echocardiography (ICE) for imaging of the swine cardiovascular system; and (2) defines normal values using these techniques in a closed chest large swine model (n = 24, body weight 50-114 kg). Multiplane TEE increased success rate over the single plane (the variable plane array only at 0 degrees ) TEE (P < 0.01) for imaging the left ventricular (LV) long-axis view (100% vs 50%), LV outflow tract (100% vs 33%), right atrium and its appendage (79% vs 33%), ascending aorta (100% vs 58%), and aortic arch (100% vs 17%). TEE-derived normal values at end-diastole (ED) and end-systole (ES) were: LV internal diameter (ID) = 49 +/- 3 mm (ED) and 33 +/- 4 mm (ES); LV wall thickness = 7 +/- 1 mm (ED); right ventricular (RV) ID = 24 +/- 4 mm (ED); RV wall thickness = 4 +/- 2 mm (ED); left atrial ID = 48 +/- 6 mm (ES); aortic root ID = 26 +/- 3 mm (ES); LV volume = 157 +/- 49 ml (ED) and 57 +/- 22 ml (ES). Baseline LV ejection fraction (64% +/- 6%), Doppler-derived stroke volume (86 +/- 14 ml), and cardiac index (107 ml/min per kg) were determined. Basal normal values, except for an elevated cardiac index in swine, are comparable to those reported for human adults. Multiplane TEE provided better overall cardiac imaging than did single plane TEE. ICE provided higher resolution imaging of individual cardiac chambers and structures when the ultrasound catheter was introduced into the right or left heart, but whole heart imaging was limited by ultrasound penetration at 12.5 MHz. Normal indices of chamber size and function provide a reference for the physiological significance of induced pathological states in this relevant animal model.

Journal Article↗