Marc Wish

Importance of left atrial timing in the programming of dual-chamber pacemakers☆

To determine the hemodynamic effect of different programmed atrioventricular (AV) delays and the importance of the actual timing of left atrial (LA) depolarization, 16 patients with dual-chamber pacemakers were studied and all were found to have an optimal programmed AV delay for cardiac function. However, randomly chosen AV delays of 150, 200 or 250 ms actually provided worse stroke volume than VVI pacing in 7 patients. The optimal programmed AV delay was variable between patients and was related to the interatrial conduction delay, measured as the time from right atrial pacing artifact to LA depolarization (mean 144 +/- 82 ms, range 70 to 380.) Patients with short interatrial delays (less than or equal to 90 ms) were served better by shorter programmed AV delays (150 ms), and patients with longer interatrial delays (greater than or equal to 120 ms) were served better by longer programmed AV delays (greater than or equal to 200 ms) (p less than 0.05). Furthermore, as pacing mode changed from dual-chamber sequential pacing (DVI) to atrial synchronous ventricular pacing (VDD), the LA to ventricular sequence increased from 6 +/- 81 ms to 137 +/- 50 ms (p less than 0.001). This change in the LA to ventricular sequence with mode change produced a significant decrease in stroke volume (p less than 0.05). Thus, the optimal programmed AV delay in patients with dual-chamber pacemakers is predicted by the relation of LA and ventricular activation. Because interatrial conduction delays vary widely, optimal programming requires knowledge of the LA to ventricular sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

M-mode echocardiograms for determination of optimal left atrial timing in patients with dual chamber pacemakers

To determine if the A wave of the mitral valve echocardiogram can be used as a marker for left atrial (LA) activity and assist in the programming of dual chamber pacemakers, 156 echocardiograms with the mitral A wave present were obtained from 23 patients with dual chamber pacemakers, all of whom had bipolar esophageal recordings of LA depolarization. Twelve of these patients also underwent hemodynamic study with cardiac function determined at 5 different pacemaker settings: ventricular demand pacing and dual chamber sequential pacing at 0 or 25, 150, 200 and 250 ms programming atrioventricular (AV) delay. The time delay from right atrial pacing artifact to onset and peak of mitral A wave was linearly related to the time from atrial pacing artifact to LA depolarization on the esophageal lead (p less than 0.001). As pacing mode changed from dual chamber sequential pacing (DVI) mode to atrial synchronous-ventricular pacing (VDD), the A wave came earlier relative to the ventricular pacing spike, linearly related to the LA to ventricular extension with mode change determined with the esophageal lead (r = 0.94, p less than 0.001). The time from atrial pacing to peak of A wave was shorter in patients whose optimal programmed AV delay was 150 ms compared with those whose optimal AV delay was 200 or 250 ms (p less than 0.02). At the optimal programmed delay for cardiac output, the peak of the A wave was an average of 13 +/- 36 ms after the ventricular pacing spike.(ABSTRACT TRUNCATED AT 250 WORDS)

Steroid-Tipped Leads Versus Porous Platinum Permanent Pacemaker Leads: A Controlled Study

WISH, M., ET AL.: Steroid‐Tipped Leads Versus Porous Platinum Permanent Pacemaker Leads: A Controlled Study. There is little data directly comparing steroid‐tipped permanent pacemaker leads to otherwise state‐of‐the‐art porous platinum leads. Eighteen patients receiving unipolar generators capable of low voltage outputs were randomized at the time of implant to receive either steroid‐tipped leads or porous platinum leads. All leads were unipolar, tined, passive fixation, and placed in the right ventricular apex or atrial appendage. This study is single center. At implant, threshold pulse width was determined at 3 voltages (2.5, 1.5, and 0.8 V). Follow‐up thresholds were determined at weeks 1, 2, 3, and 4, and at 3 and 6 months. There was no difference in implant thresholds or amplitudes for sensing. By 2 weeks postimplant, lower thresholds were noted for the steroid leads, and this discrepancy grew more significant with time. There was no significant postimplant rise in threshold for steroid‐tipped leads. At 6 months, the average threshold pulse width for ventricular steroid leads at 0.8 V was 0.3 ± 0.1 msec. In contrast, five patients with standard leads did not capture at maximum pulse width at 0.8 V (p < 0.0001). There was no significant difference in the amplitude of the chronic atrial electrogram. This study shows steroid‐tipped leads to offer a significant advantage in reducing thresholds early postimplant and chronically.

Sotalol for refractory sustained ventricular tachycardia and nonfatal cardiac arrest

The efficacy and safety of sotalol were assessed by electrophysiologic testing and ambulatory recordings in 16 patients with recurrent sustained ventricular tachycardia (VT) or nonfatal cardiac arrest who were refractory to an average of 4.8 conventional antiarrhythmic agents. Twenty-four-hour ambulatory recordings were performed before and after sotalol therapy. Fourteen patients underwent baseline electrophysiologic study and sustained VT was inducible in 12. Oral sotalol (320 to 960 mg/day) completely suppressed inducible sustained VT in 7 patients (58%), with modification in 3 (25%). Ventricular premature complexes were suppressed from baseline (mean +/- standard deviation) 431 +/- 616 to 60 +/- 110/hr (p less than 0.03). After a mean follow-up of 19 +/- 7 months, 12 of 14 patients receiving sotalol treatment had successful suppression of ventricular premature complexes (60 +/- 85/hr) and remained clinically free of sustained VT, except 2 who needed additional antiarrhythmic drugs to suppress the recurrent sustained VT. One patient died suddenly after 25 months of sotalol treatment. No severe side effects were noted during sotalol therapy. This study demonstrates that sotalol is a well-tolerated, effective antiarrhythmic agent in patients at high-risk for sudden death. It appears to be beneficial in patients who did not benefit from multiple drug treatment.

Percutaneous Catheter Ablation Treatment of Recurring Atrial Arrhythmias After Surgical Ablation

BACKGROUND Surgical ablation for atrial fibrillation is associated with early and late recurrence of atrial arrhythmias. Although early arrhythmias may be controlled with conventional treatment, late arrhythmias are often highly symptomatic and relatively hard to manage with antiarrhythmic drugs and electrical cardioversion. This study explores a single-center experience with catheter ablation to treat late failures (>3 months) after surgery. METHODS This is a prospective longitudinally designed study assessing all patients who underwent surgical treatment for atrial fibrillation as a standalone or concomitant with other procedures by multiple surgeons. All patients were monitored according to the Heart Rhythm Society guidelines. RESULTS From January 2005 to present, 400 consecutive patients operated on by multiple surgeons were enrolled. The overall success rate per the Heart Rhythm Society guidelines was 87% and 84% (off antiarrhythmic drugs, 78% and 73%) at 12 and 24 months, respectively. Sixteen patients (4%) were referred for electrophysiology study after the surgical procedure (15 Cox-maze III or IV, 1 pulmonary vein isolation). The average age was 61.1+/-15.2 years; the mean left atrium size was 5.1+/-0.7 cm; and the mean time to ablation was 16.9+/-10 months. In 16 patients radiofrequency ablation was applied to treat the following atrial arrhythmias: 7 right atrial flutter or tachycardia, 3 left atrial flutter, 1 biatrial flutter, and 5 left atrial tachycardia. Six patients required a subsequent radiofrequency ablation intervention including 4 patients who required atrioventricular nodal ablations. The long-term success rate for the subsequent catheter ablation in these 16 patients (follow-up of 42.9+/-9.8 months) determined by the rate of sinus rhythm as captured by electrocardiography was 94%. Fifty-three percent of the patients (n=8) in sinus rhythm were still taking antiarrhythmic drugs; 8 patients remained on warfarin. There was 1 late noncardiac death and no late strokes. CONCLUSIONS In a certain subset of patients, unsuccessful surgical ablation of atrial fibrillation may result in symptomatic atrial arrhythmia. If indicated, catheter ablation is a safe and effective intervention with a relatively high success rate. The combination of the two treatment modalities, catheter and surgical ablation, can improve the outcome even in complex patients.

Minimally Invasive Stand-Alone Cox-Maze Procedure for Patients With Nonparoxysmal Atrial Fibrillation

BACKGROUND Catheter-based ablation for atrial fibrillation (AF) performed percutaneously is shown to be limited in patients with nonparoxysmal AF (non-PAF). The full Cox-Maze surgical procedure demonstrated good success with non-PAF, but concerns were raised regarding increased morbidity eliminating the effect of the success rate. This study assessed the safety and efficacy of a stand-alone on-pump Cox-Maze procedure for non-PAF. METHODS Since 2005, 104 stand-alone Cox-Maze procedures for non-PAF were performed through a right minithoracotomy (6 cm) with femoral cannulation. Patients were monitored prospectively through our AF registry. Rhythm was verified by electrocardiogram and 24-hour Holter monitoring. Health-related quality of life (SF-12 Health Survey, Quality Metric, Lincoln, RI) and AF symptoms were assessed. RESULTS Patients were a mean age of 55.9±9.0 years, and 78% had long-standing persistent AF. Patient outcomes included no operative (30 days) deaths or renal failure, 1 pacemaker, and 1 transient ischemic attack. The return to sinus rhythm at 6, 12, 24, 36 months was 94%, 94%, 92%, 92%, and off antiarrhythmic drugs was 87%, 87%, 79%, 80%, respectively. The success rate at 6 months after the initial 20 patients improved from 89% to 94%. Multivariate analysis found duration of AF predicted rhythm at 6 months (odds ratio, 1.15; 95% confidence interval, 1.01 to 1.31; p=0.04). Significant improvement was noted for health-related quality of life and decreased AF symptoms at 1 year. CONCLUSIONS The long-term success rate after the Cox-Maze III procedure in a challenging group of non-PAF patients is acceptable. Our experience suggests the development of educational strategies to overcome the initial learning curve and patient selection criteria for AF surgical ablation.

Transdiaphragmatic Implantation of the Automatic Implantable Cardioverter Defibrillator

A new surgical approach for implantation of the automatic implantable cardioverter defibrillator without thoracotomy was used in 12 patients, aged 46 to 72 years. Preimplantation arrhythmia was ventricular tachycardia in 7 patients and ventricular fibrillation in 5 patients. The mean ejection fraction was 19%. Six patients were at high risk for general anesthesia for a variety of medical problems, and 2 patients had had a previous cardiac operation. Epidural anesthesia was used in 8 patients without intubation. The surgical approach used a longitudinal epigastric extraperitoneal incision with access to the heart through an incision made in the central tendon of the diaphragm. Two patches and two epicardial sensing leads were placed in all patients. All patients but one could be defibrillated with 20 J or less. There was no operative mortality and minimal morbidity. There were two late deaths due to heart failure. Thus, the transdiaphragmatic approach provides an excellent exposure for automatic implantable cardioverter defibrillator implantation, avoids general anesthesia and thoracotomy, and can be used after a previous cardiac operation.

Reduced acetylation of procainamide by para-aminobenzoic acid

Acetylation is the major route of metabolism of many drugs including the antiarrhythmic agent procainamide. Coadministration of para-aminobenzoic acid was observed to decrease the biotransformation of procainamide to N-acetylprocainamide in a patient with rapid acetylation kinetics. In view of the distinct antiarrhythmic and toxic properties of procainamide and N-acetylprocainamide, the observed drug interference may have great clinical relevance in long-term oral antiarrhythmic therapy and in instances where other drugs converge for acetylation.

Noninvasive electrophysiologic study using standard permanent pacemakers in patients with spontaneous sustained ventricular tachycardia or ventricular fibrillation

Permanent pacemakers capable of noninvasive electrophysiologic testing were used to study and treat 26 patients with spontaneous sustained ventricular tachycardia (VT) or fibrillation (VF). One hundred nine episodes of sustained VT or VF were induced in these patients. In 8 patients spontaneous VT was reverted by noninvasive means. Drug changes based on noninvasive testing were made in 12 patients. In the 1- to 67-month follow-up period, drug therapy based on noninvasive electrophysiologic testing was predictive of outcome in patients with spontaneous arrhythmias. Thus, noninvasive electrophysiologic testing using permanent pacemakers is a useful method for studying and treating patients with recurrent sustained ventricular arrhythmias.

A New Advancement in Noninvasive Electrophysiology: A Standard Laboratory Stimulator Pulse Coupled with an Implanted Pacemaker

A new device for coupling the pulse from a standard laboratory stimulator to commercially available implanted pacemakers for use in noninvasive electrophysiology testing has been developed. When programmed to an electrophysiology mode, a 37 kHz carrier wave, generated by the programmer, maintains communication with the implanted pacemaker. Stimuli generated from a standard lab stimulator cause a break in the carrier wave and an output from the pacemaker. Cycle lengths as short as 127 msec can be attained. In addition to standard electrophysiology testing, this noninvasive electrophysiological technique can be used to fibrillate the heart to test the efficacy of automatic implantable cardioverter/defibrillators.