Douglas P Zipes

BACKGROUND: Fragmented QRS (fQRS) on a 12-lead electrocardiogram (ECG) is associated with myocardial scar in patients with coronary artery disease (CAD).

OBJECTIVE: We postulated that fQRS is a predictor of cardiac events and mortality in patients who have known CAD or who are being evaluated for CAD.

METHODS: The cardiac events (myocardial infarction, need for revascularization, or cardiac death) and all-cause mortality were retrospectively reviewed in 998 patients (mean age 65.5 +/- ...

OBJECTIVES: We compared the electrophysiologic effects on atrioventricular (AV) node physiology of selective "fast" versus selective "slow" pathway radiofrequency ablation in 42 patients with drug-resistant AV node reentrant tachycardia who underwent 51 ablation attempts to prevent tachycardia recurrence while preserving AV conduction.

BACKGROUND: The recent introduction of radiofrequency ablation to treat AV node reentrant tachycardia allows the opportunity to study the effects of ...

OBJECTIVES: The aim of this study was to determine whether patients with ventricular arrhythmias in the absence of coronary artery disease also have abnormalities in sympathetic innervation.

BACKGROUND: We have previously shown by cardiac sympathetic scintigraphy using iodine-123-metaiodobenzylguanidine (I-123-MIBG) that patients with ventricular tachycardia after myocardial infarction have regional cardiac sympathetic denervation. It is not known whether patients with ventricular ...

We examined the influence of ventricular tachycardia (VT) cycle length and antiarrhythmic drugs on the frequency of VT termination and acceleration by single and double extrastimuli and right ventricular burst pacing. In 57 patients, 89 episodes of sustained VT (32 control, 57 drug) were induced by programmed electrical stimulation. Overall, 60 of 89 (67%) episodes of ventricular tachycardia were terminated by means of programmed electrical stimulation. In patients with relatively slow ...

The vagal nerves modulate adrenergic effects on sinus cycle length, atrioventricular (AV) nodal conduction, and refractoriness of atria and ventricles. We tested whether varying levels of vagal-sympathetic input could yield the same spontaneous sinus cycle length but also alter effective refractory periods of the right atrium, right ventricle, and left ventricle and AV nodal conduction times. Dogs anesthetized by alpha-chloralose were studied in the open-chest, neurally decentralized ...

INTRODUCTION: We have shown previously that acute atrial dilation prolonged atrial refractoriness. We hypothesized that this increase in refractoriness might be heterogeneous and could create an electrophysiologic substrate leading to atrial fibrillation. The purpose of the present study was to test that hypothesis.

METHODS AND RESULTS: We studied 23 anesthetized open chest dogs. Bipolar plunge electrodes were placed in the medial free wall of the right atrium (thin region) and in the ...

BACKGROUND: The purpose of this study was to investigate the functional pathways of efferent vagal innervation to the atrial myocardium and sinus and atrioventricular (AV) nodes.

METHODS AND RESULTS: Using vagally induced atrial effective refractory period shortening, slowing of spontaneous sinus rate, and prolongation of AV nodal conduction time as end points of vagal effects, we determined the actions of phenol and epicardial radiofrequency catheter ablation (RFCA) applied to different ...

BACKGROUND: Conduction abnormalities serve as a substrate for ventricular fibrillation (VF) in patients with Brugada syndrome (BS). Signal-averaged electrograms can detect late potentials, but the significance of conduction abnormalities within the QRS complex is still unknown. The latter can present as multiple spikes within the QRS complex (fragmented QRS [f-QRS]). We hypothesized that f-QRS could indicate a substrate for VF and might predict a high risk of VF for patients with ...

BACKGROUND: Radiofrequency energy has been used safely and successfully to eliminate accessory pathways in patients with the Wolff-Parkinson-White syndrome and the substrate for atrioventricular nodal reentrant tachycardia. However, this form of ablation has had only limited success in eliminating ventricular tachycardia in patients with structural heart disease. In contrast, direct-current catheter ablation has been used successfully to eliminate ventricular tachycardia in patients with ...

This study examined the usefulness of programmed electrical stimulation in managing 83 patients who had ventricular tachycardia not due to coronary artery disease. Among 39 patients with a history of sustained ventricular tachycardia, programmed stimulation induced ventricular tachycardia in 14 of 14 patients with mitral valve prolapse or primary electrical disease (arrhythmias without evidence of structural heart disease) and in 13 of 25 with cardiomyopathy (total 27 of 39, 69 percent). ...

To examine the effects of ischemic preconditioning on efferent autonomic responses following acute transmural myocardial ischemia/infarction (MI), the time course and extent of efferent sympathetic and vagal denervation were compared between control dogs that received a one-stage sustained coronary occlusion and preconditioned dogs that received four 5-minute coronary occlusions separated by 5 minutes of reperfusion before sustained occlusion. Effective refractory periods (ERP) basal and ...

To determine the time course of efferent sympathetic denervation after transmural myocardial infarction (TMI) and of efferent vagal denervation after transmural or nontransmural myocardial infarction (NTMI), we measured effective refractory periods (ERP) basal and apical to TMI or NTMI in secobarbital-anesthetized, open-chest dogs. In eight dogs with latex-induced TMI, bilateral ansae subclaviae stimulation shortened ERP at all 45 apical and basal test sites before latex injection. After ...

Transmural myocardial infarction in dogs produces denervation of sympathetic nerves in viable myocardium apical to the infarct that may be arrhythmogenic. It is unknown whether sympathetic denervation occurs in humans. The purpose of this study was to use iodine-123-metaiodobenzylguanidine (MIBG), a radiolabeled guanethidine analog that is actively taken up by sympathetic nerve terminals, to image noninvasively the cardiac sympathetic nerves in patients with and without ventricular ...

OBJECTIVE: To assess the out-of-hospital cardiac arrest (OHCA) survival advantage after providing police with automated external defibrillators (AEDs) in rural and suburban Indiana.

METHODS: An observational evaluation was conducted in six Indiana counties (population: 464,741) before (retrospective) and after (prospective) training and equipping police with AEDs. The primary outcome evaluated was survival to hospital discharge for all cases of ventricular tachycardia/ventricular ...