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David Schwartzman

Publications and source records attributed to David Schwartzman.

At least 19 recordsLinked to original sources
PubMed2006

Direct comparison of computed tomography and magnetic resonance imaging for characterization of posterior left atrial morphology.

OBJECTIVE: Accumulating evidence points to the central importance of the posterior left atrium (PLA) for atrial fibrillation (AF). Catheter ablation intended to cure AF is increasingly practiced; performance and assessment of this procedure is enhanced by accurate imaging of PLA anatomy. Prior reports have suggested that both computed tomographic (CT) and magnetic resonance (MR) imaging techniques provide accurate PLA images. These techniques have never been compared directly. MATERIALS AND METHODS: Twenty patients referred for catheter ablation underwent preoperative imaging using both CT and MR. Each technique was used to create a multidimensional image of the PLA. RESULTS: Within patients, morphologic and dimensional PLA indices, including number of individual pulmonary venoatrial junctions, presence of ostial branches, circumference of each venoatrial junction, venoatrial junction "non-circularity", and distance between ipsilateral superior and inferior venoatrial junctions, were well correlated. CONCLUSIONS: CT and MR-based images of the PLA appear comparable. Technique selection should involve considerations of toxicity, tolerance, and local resources.

Adult↗
PubMed2006

Velocity vector imaging to quantify ventricular dyssynchrony and predict response to cardiac resynchronization therapy.

Velocity vector imaging is a novel quantitative echocardiographic technique that was applied to routine grayscale echocardiographic images of 23 patients with heart failure who underwent cardiac resynchronization therapy. The hypothesis was tested that velocity vector imaging can quantify left ventricular mechanical dyssynchrony and predict response to resynchronization therapy. Tissue velocities were determined by the automated tracking of periodic B-mode image patterns on digital cine loops from standard apical 4-chamber, 2-chamber, and long-axis views, with the user tracing the mid left ventricular wall from a single frame. Dyssynchrony was determined as the greatest opposing wall peak longitudinal systolic velocity delay from the 3 views. Responders, defined as those with >or=15% increases in the ejection fraction, had greater baseline dyssynchrony than nonresponders (opposing wall velocity delays of 131 +/- 83 vs 52 +/- 60 ms, p <0.05), and >or=75 ms predicted response with 85% sensitivity and 80% specificity when followed 8 +/- 5 months after resynchronization therapy. Baseline electrocardiographic QRS duration was not predictive in the same patients. In conclusion, echocardiographic velocity vector imaging has potential for clinical utility.

Blood Flow Velocity↗
PubMed2006

Echocardiographically guided left atrial ablation: characterization of a new technique.

BACKGROUND: Several techniques for percutaneous catheter-based radiofrequency ablation of left atrial myocardium have been described. Each is potentially limited by anatomic inaccuracy, radiation requirement, cardiac/extracardiac collateral damage, proarrhythmia, lesion impermanence, or unclear procedural endpoint. OBJECTIVES: The purpose of this study was to describe a new technique that may address some of these limitations. METHODS: In 200 consecutive patients with atrial fibrillation (AF), complete ablative encircling of right and left pulmonary venous vestibules was performed using radiofrequency energy applied via a standard ablation electrode. Lesions were guided by a collaborative nonfluoroscopic imaging strategy involving intra-left atrial echocardiography and CARTO. A discrete procedural endpoint was sought: complete electrical isolation of all myocardium subtended by the encircling lesions. RESULTS: After a procedure in which the total fluoroscopy time averaged 6 minutes, isolation was achieved on the left and right sides in 198 and 199 patients, respectively. In addition to the vestibule-encircling lesions, isolation required one or more additional focal lesions within the subtended myocardial territory in the majority of left vestibules and in a minority of right vestibules. Significant procedural morbidity was observed, including cerebroembolism resulting in death and mesenteric embolism resulting in hemicolectomy. Procedural success, defined at 2 years after the initial procedure and requiring no interim procedure, antiarrhythmic drug therapy, or apparent arrhythmia burden, was observed in a significantly greater proportion of patients with a paroxysmal (87%) than persistent AF (60%) syndrome. Only a small proportion of patients with recurrent AF had recurrence of conduction in previously isolated zones. CONCLUSION: This technique may have advantages over those previously reported, including improved anatomic accuracy, improved lesion safety and efficacy, and diminished radiation exposure.

Adult↗
PubMed2006

Genetic susceptibility to atrial fibrillation in patients with congestive heart failure.

BACKGROUND: Previous reports demonstrate an association between atrial fibrillation (AF) and certain polymorphisms in genes controlling the production of angiotensin-converting enzyme (ACE) and endothelial nitric oxide synthase (eNOS). OBJECTIVES: The purpose of this study was to examine the association between polymorphisms of ACE and eNOS gene complexes and AF in an unselected series of patients with congestive heart failure (CHF). METHODS: In each of the 340 unselected, unrelated patients with CHF, common polymorphisms in ACE (I/D) and eNOS (T786C, G894T, and intron 4b/a) gene complexes were evaluated. Associations between individual genotypes and the presence of AF were assayed. RESULTS: AF was present in 51 patients (15%) and was significantly associated with the ACE D/D (odds ratio 1.5) and eNOS 894 T/T genotypes (odds ratio 3.2). There were no significant associations between AF and eNOS 786 or eNOS intron 4 genotypes. CONCLUSION: In patients with CHF, the presence of AF was significantly associated with certain ACE and eNOS genotypes.

Atrial Fibrillation↗
PubMed2006

Utility of adjunctive single oral bolus propafenone therapy in patients with atrial defibrillators.

AIMS: Previous studies have demonstrated that ambulatory atrial defibrillation shocks delivered by an implantable cardioverter-defibrillator (ICD) are safe and effective, but poorly tolerated. Separate studies have demonstrated the utility of single oral bolus propafenone for conversion of recent-onset atrial fibrillation (AF); however, most patients were hospitalized, had no structural heart disease, were taking no other antiarrhythmic drugs, and were not exposed to concomitant shock. We hypothesized that a single oral bolus dose of propafenone given early after onset would be a safe and effective adjunct to ICD-based AF therapy and improve overall therapy tolerance. METHODS AND RESULTS: A randomized three-way crossover study design was used to compare three strategies, deployed in the ambulatory setting early after AF episode onset in 35 ICD patients with advanced, drug refractory episodic/persistent syndromes, many of whom had structural heart disease and were taking other antiarrhythmic drugs: (i) single oral bolus propafenone (600 mg), followed by ICD shock if necessary; (ii) single oral bolus placebo, followed by ICD shock if necessary; and (iii) no oral bolus therapy and ICD shock if necessary (no bolus). Antiarrhythmic efficacy, defined by the restoration of sinus rhythm within 24 h, was similar during propafenone (81%) and no-bolus strategies (84%); both were significantly higher than during placebo strategy (62%). Propafenone was well tolerated and not associated with proarrhythmia. Shock use was significantly lower during propafenone strategy (19%) than during no-bolus strategy (55%); this was correlated with improved patient tolerance. CONCLUSION: Adjunctive use of single oral bolus propafenone is safe and effective in patients with an ICD and improves patient tolerance of device-based AF therapy.

Administration, Oral↗
PubMed2006

High-frequency jet ventilation: utility in posterior left atrial catheter ablation.

BACKGROUND: Percutaneous catheter ablation in the posterior left atrium (LA) is a technically demanding procedure that in our experience is best accomplished using general anesthesia, including endotracheal intubation and mechanical ventilation. However, using conventional intermittent positive-pressure ventilation (IPPV) technique, we were dissatisfied with motion of the posterior LA. This occurred during changes in lung volume, which destabilized ablation electrode-endocardial contact. We hypothesized that use of high-frequency jet ventilation (HFJV), a low-volume, fast-rate technique, would reduce posterior LA motion and thus facilitate the ablation procedure. OBJECTIVES: The purpose of this study was to demonstrate that, relative to IPPV, HFJV reduces posterior LA motion and facilitates catheter ablation in this region. METHODS: Patients who underwent posterior LA ablation using HFJV (n = 36) were retrospectively compared with those in whom IPPV (n = 36) was used. Indices examined included number of radiofrequency energy applications, electrode temperature, and procedure time. A prospective direct comparison of the impact of HFJV and IPPV on LA volume and mechanical function was performed in an additional 10 patients. RESULTS: Fewer ablation lesions were required in the HFJV group because of fewer incidences of ablation electrode dislodgment, resulting in significantly decreased procedure time. Although there was no significant difference in maximal electrode temperature achieved during radiofrequency application, temperature variation was diminished in the HFJV group. Direct comparison demonstrated that HFJV produced less variation in LA volume, pressure, pulmonary vein blood flow velocity, and posterior LA position than IPPV. CONCLUSION: Relative to IPPV, HFJV yields a more stable posterior LA environment, thus facilitating catheter ablation. Use of HFJV may be applicable to other interventional cardiovascular procedures.

Blood Flow Velocity↗
PubMed2006

Electrocardiographic events preceding onset of atrial fibrillation: insights gained using an implantable loop recorder.

INTRODUCTION: Previous reports demonstrate that individual patients may have distinctive electrocardiographic patterns preceding atrial fibrillation (AF) onset. However, these observations are based on single recordings, and are thus limited by their "snapshot" derivation; it is unclear whether patterns observed on these recordings are consistent over time. We hypothesized that the use of an implantable loop recorder (ILR) would be feasible for serial, long-term characterization of electrocardiographic events preceding AF onset. METHODS AND RESULTS: An ILR was implanted in 29 patients with AF. Patients were instructed to activate the device immediately upon experiencing AF symptoms. Analysis focused on the electrocardiographic segment immediately preceding AF; each segment was classified as one of six patterns: short/long, normal sinus rhythm, absolute sinus bradycardia, relative sinus bradycardia, absolute sinus tachycardia, or relative sinus tachycardia. From a total of 318 device activations, 105 AF onsets were suitable for analysis, acquired from 21 patients over a mean follow-up interval of 7 months. Although AF was frequently triggered by an atrial premature beat that emerged during normal sinus rhythm, most patients demonstrated a variety of onset patterns. Degeneration of uniform atrial tachycardia to AF was rare. Significant delay in device activation relative to AF onset was common, as was activation in the absence of AF. CONCLUSIONS: Using the ILR, serial, long-term characterization of electrocardiographic events preceding AF onset was feasible, and typically demonstrated a varied pattern within individuals. There was significant incongruity between symptomatic and electrocardiographic AF burden. As described here, ILR technology is inadequate for the purpose of accurate characterization of AF burden.

Atrial Fibrillation↗
PubMed2005

Utility of echocardiographic radial strain imaging to quantify left ventricular dyssynchrony and predict acute response to cardiac resynchronization therapy.

Echocardiographic strain imaging was used to quantify radial mechanical dyssynchrony in 38 patients who underwent cardiac resynchronization therapy. Dyssynchrony, defined as the time difference of peak radial strain in the septum versus the posterior wall, was significantly greater in patients with acute hemodynamic responses, and changes in radial dyssynchrony correlated with changes in stroke volume. A > or =130-ms difference in septal versus posterior wall peak strain when combined with a favorable left ventricular lead position was strongly predictive of immediate improvement in stroke volume with resynchronization therapy (95% sensitivity, 88% specificity), regardless of electrocardiographic QRS duration.

Aged↗
PubMed2005

Sensor guided ablation procedure of left atrial endocardium.

In this paper, we present a sensor guided ablation procedure of highly motile left atrium. It uses a system which automatically registers the 4D heart model with the position sensor on the catheter, and visualizes the heart model and the position of the catheter together in real time. With this system clinicians can easily map the motile left atrium shape and see where the catheter is inside it, therefore greatly improve the efficiency of the ablation operation.

Catheter Ablation↗
PubMed2005

Impact of atrial fibrillation duration on postcardioversion recurrence.

BACKGROUND: "Begetting," a mechanistic tenet of atrial fibrillation (AF), stipulates that the rate of recurrence of AF after cardioversion is proportional to the preceding arrhythmia duration. However, recent reports suggest that, for brief durations, the incidence of early recurrence of AF (ERAF) is inversely proportional to duration. These reports were based on potentially biased data. OBJECTIVES: We performed a prospective study to examine the impact of AF duration on postcardioversion recurrence. METHODS: Forty-four patients underwent placement of an implantable cardioverter-defibrillator (ICD) capable of delivering patient-elicited AF cardioversion shocks. Subsequently, in the ambulatory setting, the timing of shocks in relationship to perceived AF onset was randomly assigned within individuals to early (as soon as possible) or delayed (1 day later). RESULTS: During a follow-up averaging 199 days per patient, a total of 61 AF episodes among 17 patients occurred for which a patient-elicited cardioversion shock was delivered. Twenty-three shocks were delivered using early protocol (mean 6.8 hours after AF onset), and 38 shocks were delivered using delayed protocol (mean 34.7 hours after AF onset). The incidence of ERAF was significantly lower using the delayed protocol. CONCLUSION: A strategy of approximately 24-hour delay in cardioversion shock timing decreased the incidence of ERAF, relative to a shock delivered within a few hours of AF onset. This observation has important mechanistic and therapeutic implications.

Adult↗
PubMed2005

Serial evaluation of atrial tachyarrhythmia burden and frequency after implantation of a dual-chamber cardioverter-defibrillator.

UNLABELLED: Serial evaluation of AT burden and frequency after implantation of D-ICD. BACKGROUND: We sought to characterize atrial tachyarrhythmia (AT) burden and frequency after implantation of a dual-chamber implantable cardioverter-defibrillator (D-ICD). METHODS AND RESULTS: A total of 149 subjects underwent implantation of a D-ICD (Jewel AF model 7250, Medtronic, Inc.) for the primary indication of drug-resistant AT, and were followed for at least 12 months during which device programming was constant. The device employed atrial overdrive pacing as well as shocks to terminate episodes of AT. Arrhythmia burden and frequency were evaluated during the 0- to 6-month follow-up and and 6- to 12-month follow-up intervals. A majority of subjects (62%) received a type I/III antiarrhythmic drug during follow-up. The median arrhythmia burden decreased from 8.2 hours/month during 0-6 months to 3.3 hours/month during 6-12 months (P=0.004); this result was driven primarily by the subgroup with persistent AT prior to device implantation. There was no significant change in the median AT frequency (2.2 vs 1.0 episodes/month). There was a significant decrease in the median shock frequency (0.32 vs 0.00 shocks/month, P=0.003) and an increase in shock efficacy (85.5% vs 94.9%, P=0.01). CONCLUSIONS: Device-based treatment of AT, in association with antiarrhythmic drugs, yields a significant time-dependent decrease in AT burden but not frequency.

Aged↗
PubMed2004

A mechanism for immediate reduction in mitral regurgitation after cardiac resynchronization therapy: insights from mechanical activation strain mapping.

OBJECTIVES: We tested the hypothesis that an immediate reduction in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT) results from improved coordinated timing of the papillary muscle insertion sites, using the novel approach of mechanical activation strain mapping. BACKGROUND: Heart failure patients with left bundle branch block often benefit acutely from CRT; however, the role and mechanism of reduction of MR are unclear. METHODS: Twenty-six consecutive patients undergoing CRT with at least mild MR were studied (ejection fraction 24 +/- 6%; QRS duration 168 +/- 30 ms). Echocardiographic Doppler and strain imaging was performed immediately before and the day after CRT, as well as in 10 normal control subjects. Mechanical activation sequence maps were constructed using longitudinal strain from 12 basal and mid-LV sites, with color coding of time-to-peak strain. RESULTS: Mitral regurgitation by the volumetric method consistently decreased after CRT: regurgitant volume from 40 +/- 20 ml to 24 +/- 17 ml and regurgitant fraction from 40 +/- 12% to 25 +/- 14% (both: p < 0.001 vs. baseline). Normal controls had uniform segmental time-to-peak strain, with a difference of only 12 +/- 8 ms between all segments. In contrast, CRT patients at baseline had a 106 +/- 74 ms time delay between papillary muscle insertion sites (p < 0.001 vs. normal). This interpapillary muscle time delay shortened after CRT to 39 +/- 43 ms (p < 0.001 vs. baseline) and was significantly correlated with reductions in mitral regurgitant fraction (r = 0.77, p < 0.001). CONCLUSIONS: Cardiac resynchronization therapy significantly and immediately reduced MR. Improved coordinated timing of mechanical activation of papillary muscle insertion sites appears to be a mechanistic contributor to immediate MR reduction by CRT.

Aged↗
PubMed2004

Usefulness of echocardiographic tissue synchronization imaging to predict acute response to cardiac resynchronization therapy.

Echocardiographic tissue synchronization imaging (TSI) consists of color-coding time-to-peak tissue Doppler velocities. This study of 29 patients who underwent cardiac resynchronization therapy (CRT) demonstrated that differences in baseline time-to-speak velocities of opposing ventricular walls by TSI were greater in 15 patients, with an acute hemodynamic improvement. A >/=65 ms delay from the anterior septum to the posterior wall using the apical long-axis view had 87% sensitivity and 100% specificity for predicting an acute response. Although a subgroup without acute improvement had later decreases in end-systolic volume, suggesting that acute response underestimates long-term effects, TSI has potential to assist in guiding CRT.

Aged↗
PubMed2004

Common left pulmonary vein: a consistent source of arrhythmogenic atrial ectopy.

INTRODUCTION: The discovery of a consistent relationship between atrial anatomy and electrophysiology would have practical value and may provide insight into arrhythmia mechanism. We previously observed that anatomically common left pulmonary veins were a disproportionate source of atrial ectopy that was associated with the initiation of atrial fibrillation ("arrhythmogenic"). This report details our efforts to characterize and quantify this observation. METHODS AND RESULTS: One hundred subjects with paroxysmal atrial fibrillation underwent computed tomographic scanning to characterize left atrial anatomy and invasive electrophysiology study to characterize events associated with the initiation of atrial fibrillation. Some of these subjects also underwent radiofrequency catheter ablation. The left pulmonary vein was common in 14 subjects and was a consistent source of arrhythmogenic ectopy. This relationship was significantly stronger than for any other individual vein or ipsilateral vein combination. Myocardium located within the common vein trunk was the site of origin of the ectopy in most subjects. This myocardium did not have unique electrophysiologic properties. Catheter ablation to isolate myocardium proximal to junction between the common vein and the left atrial body cured all patients in whom the vein was the sole source of arrhythmogenic ectopy. CONCLUSION: In this cohort, a common left pulmonary vein was a consistent source of arrhythmogenic atrial ectopy.

Atrial Fibrillation↗
PubMed2004

Impact of catheter ablation on pulmonary vein morphology and mechanical function.

INTRODUCTION: Previous reports have documented that radiofrequency catheter ablation of pulmonary veins induces a significant increase in the peak velocity of transvenous blood flow. Although the magnitude of the increase infers a state of pulmonary vein stenosis, there have been no reports of direct visualization of the ablation zone. METHODS AND RESULTS: In each of 23 subjects, the myocardium investing one or more pulmonary veins (total of 42 veins) was electrically isolated by applying a confluent circumferential ablation lesion to the atrial side of the venoatrial junction. Doppler measurements of transvenous flow velocity were made before and after ablation using phased-array intracardiac echocardiography. Direct visualization of the ablation zone was performed using rotating intracardiac echocardiography, permitting assessment of shape, cross-sectional area, phasic variation in cross-sectional area, and wall thickness. In a subset of 5 subjects, a more detailed assessment of the ablation and contiguous regions was performed using three-dimensional echocardiography (rotating transducer). Prior to ablation, venoatrial junctions demonstrated noncircular shape and marked phasic variation in cross-sectional area. There was a trivial transvenous pressure gradient. After ablation, there was a significant increase in both anterograde and retrograde flow velocities and pressure gradient, the magnitudes of which were inversely proportional to the preablation and postablation areas. Direct visualization of the ablation zone revealed circumferential wall swelling, reduced cross-sectional area, and diminishment in phasic variation in cross-sectional area. Similar observations were made at contiguous nonablated sites, diminishing in magnitude as a function of distance. CONCLUSION: Pulmonary vein ablation induces significant acute changes in morphology and mechanical function that extend beyond the ablation zone.

Adult↗