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Biomedical subjects

C D Gottlieb

Publications and source records attributed to C D Gottlieb.

At least 19 recordsLinked to original sources
PubMed1999

Mechanisms of death in the CABG Patch trial: a randomized trial of implantable cardiac defibrillator prophylaxis in patients at high risk of death after coronary artery bypass graft surgery.

BACKGROUND: The CABG Patch trial compared prophylactic implantable cardiac-defibrillator (ICD) implantation with no antiarrhythmic therapy in coronary bypass surgery patients who had a left ventricular ejection fraction <0.36 and an abnormal signal-averaged ECG. There were 102 deaths among the 446 ICD group patients and 96 deaths among the 454 control group patients, a hazard ratio of 1.07 (P=0.63). The mechanisms of death were classified, and hypotheses were tested about the effects of ICD therapy on arrhythmic and nonarrhythmic cardiac deaths in the CABG Patch Trial and the Multicenter Automatic Defibrillator Implantation Trial (MADIT). METHODS AND RESULTS: The 198 deaths in the trial were reviewed by an independent Events Committee and classified by the method of Hinkle and Thaler. Only 54 deaths (27%) occurred out of hospital; 145 deaths (73%) were witnessed. Seventy-nine (82%) of the 96 deaths in the control group and 76 (75%) of the 102 deaths in the ICD group were due to cardiac causes. Cumulative arrhythmic mortality at 42 months was 6.9% in the control group and 4.0% in the ICD group (P=0. 057). Cumulative nonarrhythmic cardiac mortality at 42 months was 12. 4% in the control group and 13.0% in the ICD group (P=0.275). Death due to pump failure was significantly associated with death >1 hour from the onset of symptoms, dyspnea within 7 days of death, and overt heart failure within 7 days of death. CONCLUSIONS: In the CABG Patch Trial, ICD therapy reduced arrhythmic death 45% without significant effect on nonarrhythmic deaths. Because 71% of the deaths were nonarrhythmic, total mortality was not significantly reduced.

Anti-Arrhythmia Agents↗
PubMed1999

Antidromic reciprocating tachycardia in patients with paraseptal accessory pathways: importance of critical delay in the reentry circuit.

Previous studies in patients with antidromic reciprocating tachycardia (ART) have observed a critical anatomic requirement (> 4 cm) between an antegrade bypass tract limb and a retrograde AV nodal limb. We report two patients with ART utilizing a paraseptal accessory pathway. In both cases, a critical degree of slow conduction within the circuit provides unusual electrophysiologic substrate to overcome the expected anatomical constraints.

Adult↗
PubMed1998

Imaging technique and clinical utility for electrophysiologic procedures of lower frequency (9 MHz) intracardiac echocardiography.

Intracardiac echocardiography using a new 9-MHz ultrasound catheter was performed in 30 patients undergoing percutaneous catheter mapping and radiofrequency ablation of a tachyarrhythmia, because the imaging capabilities with this intracardiac echocardiographic catheter permit detailed identification of normal and abnormal cardiac anatomy with improved imaging depth. Intracardiac echocardiography is of significant clinical utility during ablation for guiding interatrial septal puncture, assessing placement and contact of mapping/ablation catheters, monitoring ablation lesion morphologic changes, and diagnosing procedure-related complications.

Adult↗
PubMed1998

Efficacy of radiofrequency catheter ablation for ventricular tachycardia in healed myocardial infarction.

Radiofrequency catheter ablation has been useful in the treatment of ventricular tachycardia (VT) in selected patients with healed myocardial infarction. Previous studies have demonstrated success rates of 60% to 96% for targeted VT morphologies; however, these studies included patients only after they have had successful mapping procedures and have received radiofrequency lesions. All patients referred for VT ablation from July 1992 to November 1996 were included in this analysis on an intention-to-treat basis. Ninety-five procedures were performed in 66 patients for 77 distinct presentations with tolerated, sustained VT. Fifty-five procedures were successful (58%) and 40 procedures failed. Reasons for procedural failure included failed radiofrequency application despite adequate VT mapping (21 procedures), no tolerated VT induced (12), and aborted procedures due to complications or technical difficulties (7). Fifty-five patients (71%) eventually had a successful VT ablation, although 10 required > 1 procedure. This analysis revealed factors that contribute to failure of VT ablation procedures in addition to inadequate mapping and lesion formation. Procedural difficulties, particularly the inability to induce tolerated VT, frequently prevent successful catheter ablation in patients who present with tolerated, sustained VT.

Aged↗
PubMed1998

Type I atrial flutter ablation guided by a basket catheter.

Bidirectional isthmus conduction block has been associated with a low recurrence rate after atrial flutter ablation. We present the case of a type I, typical or "counterclockwise" atrial flutter ablation guided by stimulation and recordings obtained from a basket catheter, which allowed for constant electrogram recording from splines positioned along the right lateral free wall and septum. After atrial flutter termination with radiofrequency application, the ability to record and stimulate from multiple sites in the atrium using the basket catheter was useful to detect residual bidirectional slow conduction through the isthmus. Complete isthmus block could be documented after additional radiofrequency energy applications.

Aged↗
PubMed1997

Prediction of outcome of patients with life-threatening ventricular arrhythmias treated with automatic implantable cardioverter-defibrillators using SPECT perfusion imaging.

BACKGROUND: In the present study, we examined the predictors of outcome of 103 patients with coronary artery disease and left ventricular dysfunction who had life-threatening ventricular arrhythmias and were treated with implantable cardioverter-defibrillators with the use of single-photon emission computed tomography (SPECT). METHODS AND RESULTS: During a mean follow-up of 29 months, there were 29 cardiac deaths. In comparison with patients who died, survivors had less diabetes mellitus (45% versus 19%, P < .007), higher left ventricular ejection fraction (23 +/- 9% versus 27 +/- 11%, P = .04), and fewer perfusion defects as determined with stress SPECT (15 +/- 5 versus 12 +/- 5, P < .004). Most of the perfusion defects were fixed, indicative of scarring; the extent of reversible defects did not differ (2 +/- 3 in survivors and 3 +/- 4 in nonsurvivors). Multivariate Cox survival analysis identified the number of fixed defects as the only independent predictor of death (chi 2 = 10, P = .002). There were six deaths among 42 patients (14%) with < 8 fixed defects compared with 23 deaths among 61 patients (38%) with > or = 8 defects (P = .005). The 4-year survival was better in patients with < 8 segmental fixed defects than in those with > or = 8 fixed defects (80% versus 36%) (chi 2 = 8, P = .005). CONCLUSIONS: The myocardial perfusion pattern is an important determinant of outcome in patients with life-threatening ventricular arrhythmias who are treated with a implantable cardioverter-defibrillator. The extent of scarring separates patients into high- and low-risk groups with a 2.7-fold difference in death rate.

Aged↗
PubMed1997

Repetitive monomorphic tachycardia from the left ventricular outflow tract: electrocardiographic patterns consistent with a left ventricular site of origin.

OBJECTIVES: This study sought to characterize the electrocardiographic patterns predictive of left ventricular sites of origin of repetitive monomorphic ventricular tachycardia (RMVT). BACKGROUND: RMVT typically arises from the right ventricular outflow tract (RVOT) in patients without structural heart disease. The incidence of left ventricular sites of origin in this syndrome is unknown. METHODS: Detailed endocardial mapping of the RVOT was performed in 33 consecutive patients with RMVT during attempted radiofrequency ablation. Left ventricular mapping was also performed if pace maps obtained from the RVOT did not reproduce the configuration of the induced tachycardia. RESULTS: Pace maps identical in configuration to the induced tachycardia were obtained from the RVOT in 29 of 33 patients. Application of radiofrequency energy at sites guided by pace mapping resulted in elimination of RMVT in 24 (83%) of 29 patients. In four patients (12%), pace maps obtained from the RVOT did not match the induced tachycardia. All four patients had a QRS configuration during RMVT with precordial R wave transitions at or before lead V2. In two patients, RMVT was mapped to the mediosuperior aspect of the mitral valve annulus, near the left fibrous trigone; catheter ablation at that site was successful in both. In two patients, RMVT was mapped to the basal aspect of the superior left ventricular septum. Catheter ablation was not attempted because His bundle deflections were recorded from this site during sinus rhythm. CONCLUSIONS: RMVT can arise from the outflow tract of both the right and left ventricles. RMVTs with a precordial R wave transition at or before lead V2 are consistent with a left ventricular origin.

Adult↗
PubMed1997

Characterization of the excitable gap in human type I atrial flutter.

OBJECTIVES: We sought to characterize the excitable gap of the reentrant circuit in atrial flutter. BACKGROUND: The electrophysiologic substrate of typical atrial flutter has not been well characterized. Specifically, it is not known whether the properties of the tricuspid valve isthmus differ from those of the remainder of the circuit. METHODS: Resetting was performed from two sites within the circuit: proximal (site A) and distal (site B) to the isthmus in 14 patients with type I atrial flutter. Resetting response patterns and the location where interval-dependent conduction slowing occurred were assessed. RESULTS: Some duration of a flat resetting response (mean +/- SD 40.1 +/- 20.9 ms, 16 +/- 8% of the cycle length) was observed in 13 of 14 patients; 1 patient had a purely increasing response. During the increasing portion of the resetting curve, interval-dependent conduction delay most commonly occurred in the isthmus. In most cases, the resetting response was similar at both sites. In three patients, the resetting response differed significantly between the two sites; this finding suggests that paced beats may transiently change conduction within the circuit or the circuit path, or both. CONCLUSIONS: Some duration of a flat resetting response was observed in most cases of type I atrial flutter, signifying a fully excitable gap in all portions of the circuit. The isthmus represents the portion of the circuit most vulnerable to interval-dependent conduction delay at short coupling intervals.

Action Potentials↗
PubMed1997

Right ventricular radiofrequency ablation of ventricular tachycardia after myocardial infarction.

Radiofrequency transcatheter ablation of ventricular tachycardia in the setting of a prior myocardial infarction is typically performed with application of energy to the left ventricular endocardium. In this article, two cases are described in which successful radiofrequency transcatheter ablation of ventricular tachycardia occurred with energy delivery to the right ventricular septum after failed ablation attempts from the left ventricle. Both patients had tachycardias with a left bundle branch block morphology and markedly presystolic activity recorded from the right ventricular septum. Right ventricular septal activation mapping during ventricular tachycardia should be performed in patients with left bundle branch block tachycardia morphology and coronary artery disease to maximize efficacy of the catheter ablation procedure.

Aged↗
PubMed1997

Does the initial presentation of patients with implantable defibrillator influence the outcome?

The influence of the clinical presentation on the long-term outcome in 213 consecutive patients with ICDs, ECG storage capability, and nonthoracotomy leads, was analyzed. Sixty-six patients presented with cardiac arrest (CA), 81 patients with hemodynamically stable VT, and 66 patients with syncope (SY). Patient characteristics were: mean age CA 62, VT 61, SY 61 years; mean ejection fraction CA 31%, VT 29%, SY 30%; coronary artery disease CA 71%, VT 71%, SY 64% (all P > 0.05 Fisher's exact test); female gender CA 40%, VT 14%, SY 19% (CA vs VT and SY, P < 0.005); inducibility by programmed stimulation CA 50%, VT 84%, SY 61% (VT vs CA and SY, P < 0.001, CA vs SY, P > 0.05). During a mean follow-up of 14.5 months, 29 patients died: CA 12%, VT 14%, SY 9% (P > 0.05). Comparing Kaplan-Meier curves, no difference in the time course of overall mortality was found (log-rank P > 0.05). In the CA, VT, and SY groups, 543, 1,630, and 189 ICD therapies (including antitachycardia pacing, low energy cardioversion, and defibrillation) were observed, respectively. Actuarial analysis showed a shorter interval between implantation and first ICD therapy for VT versus CA and SY (log-rank P < 0.005). Patients presenting with VT experienced earlier and more frequent ICD therapies than patients with CA or SY independent of age, ejection fraction, and heart disease. No difference in overall mortality and time course of fatal events was observed among the three groups.

Actuarial Analysis↗
PubMed1997

ICD-antiarrhythmic drug and ICD-pacemaker interactions.

Antiarrhythmic drugs and separate bradycardia pacing systems are prescribed commonly in patients with implantable cardioverter defibrillators (ICDs). Adverse effects of antiarrhythmic drugs on ICD function and adverse interactions between ICDs and pacemakers have been documented. The effect of antiarrhythmic drugs on the defibrillation threshold (DFT) in patients has not been well assessed. Most studies have been performed in animal models in which cardiac function was normal and drug doses were supraphysiologic. In addition, most studies have utilized monophasic defibrillation shock waveforms and epicardial lead systems. Despite the lack of clinical data applicable to current defibrillation systems, it appears that chronic amiodarone administration causes a significant DFT increase. In addition, antiarrhythmic drugs can influence antitachycardia pacing and tachycardia sensing. Defibrillation shocks can cause transient failure of pacemaker sensing and pacing, and cause spurious pacemaker reprogramming. Pacemaker function can result in ICD oversensing, leading to inappropriate therapy, or cause ICD undersensing, potentially resulting in failure to deliver therapy during ventricular fibrillation. The susceptibility of an ICD to undersensing appears related to the amplitude of the pacing stimulus artifact recorded by the ICD rate-sensing circuit and to the characteristics of the fibrillation electrogram. Preliminary data suggest that undersensing of ventricular fibrillation by current ICDs is an unlikely event.

Anti-Arrhythmia Agents↗
PubMed1996

Conduction block in the inferior vena caval-tricuspid valve isthmus: association with outcome of radiofrequency ablation of type I atrial flutter.

OBJECTIVES: We sought to 1) correlate conduction block in the isthmus of the right atrium between the inferior vena cava and the tricuspid annulus with the efficacy of catheter ablation of type I atrial flutter, and 2) characterize the effects of ablative lesions on the properties of isthmus conduction. BACKGROUND: There are few data on the mechanism of persistent suppression of recurrence of atrial flutter by catheter ablation. METHODS: Thirty-five patients with type I atrial flutter underwent catheter mapping and ablation. Radiofrequency lesions were applied in the isthmus. Transisthmus conduction before and after the lesions was assessed during atrial pacing in sinus rhythm from the medial and lateral margins of the isthmus at cycle lengths of 600, 400 and 300 ms and the native flutter cycle length. Isthmus conduction block was defined using multipolar recording techniques. There were three treatment groups: group 1 = radiofrequency energy applied during flutter, until termination (n = 14); group 2 = radiofrequency energy applied during atrial pacing in sinus rhythm from the proximal coronary sinus at a cycle length of 600 ms, until isthmus conduction block was observed (n = 14); and group 3 = radiofrequency energy applied until an initial flutter termination, after which further energy was applied during atrial pacing in sinus rhythm until isthmus conduction block was observed (n = 7). RESULTS: In group 1, after the initial flutter termination, isthmus conduction block was observed in 9 of the 14 patients. In each of these nine patients, flutter could not be reinitiated. In each of the remaining five patients, after the initial flutter termination, isthmus conduction was intact and atrial flutter could be reinitiated. Ultimately, successful ablation in each of these patients was also associated with isthmus conduction block. In groups 2 and 3, isthmus conduction block was achieved during radiofrequency energy application, and flutter could not subsequently be reinitiated. Before achieving conduction block, marked conduction slowing or intermittent block, or both, was observed in some patients. In some patients, isthmus conduction block was pacing rate dependent. In addition, recovery from conduction block was common in the laboratory and had a variable time course. At a mean follow-up interval of 10 months (range 1 to 21), the actuarial incidence of freedom from type I flutter was 80% (recurrence in three patients at 7 to 15 months). CONCLUSIONS: Isthmus conduction block is associated with flutter ablation success. Conduction slowing or intermittent block, or both, in the isthmus can occur before achieving persistent block. Recovery of conduction after achieving block is common. Follow-up has revealed a low rate of flutter recurrence after achieving isthmus conduction block, whether the block was achieved in conjunction with termination of flutter.

Adult↗
PubMed1996

The variable contribution of functional and anatomic barriers in human ventricular tachycardia: an analysis with resetting from two sites.

OBJECTIVES: This study sought to investigate the influence of stimulation site on the properties of the circuit in ventricular tachycardia. BACKGROUND: A fully excitable gap can be demonstrated in most human ventricular tachycardias. This requires the presence of an arc of block so that the entire circuit can recover from refractoriness within the period of the cycle length. Resetting characterizes the conduction properties of the tissue within the ventricular tachycardia circuit. Previous studies have not investigated the possibility of site-dependent differences in the resetting response. METHODS: Resetting was performed from the right ventricular apex and outflow tract in 23 patients. Two characteristics of the resetting response were analyzed: 1) the total duration of the flat portion, and 2) the slope of the increasing portion. RESULTS: A flat portion of the resetting response was observed in 18 tachycardias; in 8 of the 18, there was a significant site-dependent difference (> or = 40 ms) in the duration of the flat portion. A significant site-dependent difference in the slope of the increasing portion of the resetting curve was seen in 6 of 22 tachycardias. In all, a stimulation site-dependent change in at least one characteristic of the resetting response was seen in 12 (52%) of the 23 tachycardias. CONCLUSIONS: A stimulation site-dependent change in the flat portion of the resetting response is compatible with an arc of block that is at least partially functional in nature. A change in the slope of the increasing portion is compatible with either partially functional circuit barriers or variation in properties of conduction and refractoriness at different locations within the circuit, or both. These observations suggest that a spectrum of circuit properties may exist in humans, with a variable contribution of anatomic and functional characteristics.

Adult↗
PubMed1996

Factors associated with successful implantation of nonthoracotomy defibrillation lead systems.

Two hundred forty-three consecutive patients underwent attempted implantation of nonthoracotomy defibrillation lead (NTL) systems. The importance of clinical and lead-related factors were analyzed regarding their relation with implantation failure caused by an unacceptably high defibrillation threshold (DFT). Overall, 33 (14%) of 243 patients failed NTL implantation. Patients undergoing attempted implantation of NTL systems with monophasic shock waveforms (monophasic group, n = 145) had an incidence of failed implantation of 22% (n = 32) versus an incidence of 1% (n = 1) among patients undergoing attempted implantation by using biphasic shock waveforms (biphasic group, n = 98; odds ratio, 26.9; p < 0.001). The incidence of success and simplicity of implantation of NTL systems was markedly improved in patients undergoing NTL implantation by using biphasic shock waveforms. Clinical factors could be used to stratify patients in the monophasic group for their risk of implantation failure. In the biphasic group, no clinical factor could be correlated with a low DFT with a fully endovascular system.

Aged↗
PubMed1996

Idiopathic right ventricular outflow tract tachycardia: narrowing the anatomic location for successful ablation.

Pace mapping used to locate the site for ablation of idiopathic right ventricular outflow tract (RVOT) ventricular tachycardia remains difficult and time-consuming. A method to facilitate pace mapping and the most common site of ablation of this tachycardia are reported. In 18 consecutive patients with RVOT ventricular tachycardia, electrocardiographic criteria based on the QRS orientation in lead 1 and the R wave progression in the precordial leads were used to find pace maps matching the arrhythmia. Identical pace maps were obtained on the septum of the RVOT in 16 patients and resulted in successful ablations. These sites were concentrated in the anterior superior aspect of the RVOT determined by fluoroscopic imaging. In the remaining two cases identical pace maps could not be found in this area. The results of this study narrow the anatomic location for radiofrequency ablation of idiopathic RVOT ventricular tachycardia. This is the first description of an electrocardiography-guided approach to finding an identical pace map in the RVOT.

Adult↗