Nadim Nasir

Long-term Follow-up of Cardioverter-Defibrillator Implanted Under Conscious Sedation in Prepectoral Subfascial Position

BACKGROUND Implantable cardioverter-defibrillators (ICDs) with intravenous electrode systems and downsized generators can be implanted by use of operative techniques similar to those employed for the insertion of permanent pacemakers. However, the safety, efficacy, and long-term follow-up of simplified implantation procedures remain to be evaluated. This report is a prospective long-term evaluation of nonselected patients receiving ICDs in the prepectoral subfascial position under conscious sedation. METHODS AND RESULTS Clinical characteristics of the 231 consecutive patients included a mean age of 63 years, a male-to-female ratio of 6.4, a left ventricular ejection fraction of 0.34, a mild-to-moderate heart failure in 91%, coronary artery disease in 84%, and a history of aborted sudden cardiac death or refractory ventricular tachyarrhythmias. Insertion of transvenous leads and prepectoral subfascial ICD implantation were performed in electrophysiology laboratories under local anesthesia and conscious sedation with intravenous midazolam and propofol. Successful implantation in all patients (operation time, 80 +/- 32 minutes, mean +/- SD) irrespective of body size and skin thickness was free of major complications, including need for emergency intubation. After surgery, 1 pocket hematoma, 1 seroma, and 1 pneumothorax required treatment. There was no operative or first-month mortality. During long-term follow-up averaging 453 +/- 296 days, six leads required repositioning, but pocket erosions or infections did not occur. First-year total survival was 97%. CONCLUSIONS Implantation under conscious sedation of ICDs in the prepectoral subfascial position is a safe and effective procedure with low operative and postoperative morbidity and favorable long-term outcome.

Shocks as Predictors of Survival in Patients With Implantable Cardioverter-Defibrillators

OBJECTIVES The objective of the study was to determine whether the occurrence of shocks for ventricular tachyarrhythmias during therapy with implantable cardioverter-defibrillators (ICD) is predictive of shortened survival. BACKGROUND Ventricular tachyarrhythmias eliciting shocks are often associated with depressed ventricular function, making assessment of shocks as an independent risk factor difficult. METHODS Consecutive patients (n = 421) with a mean follow-up of 756+/-523 days were classified into those who had received no shock (n = 262) or either one of two shock types, defined as single (n = 111) or multiple shocks (n = 48) per arrhythmia episode. Endpoints were all-cause and cardiac deaths. A survival analysis using a stepwise proportional hazards model evaluated the influence of two primary variables, shock type and left ventricular ejection fraction (LVEF <35% or >35%). Covariates analyzed were age, gender, NYHA Class, coronary artery disease, myocardial infarction, coronary revascularization, defibrillation threshold and tachyarrhythmia inducibility. RESULTS The most complete model retained LVEF (p = 0.005) and age (p = 0.023) for the comparison of any shock versus no shock (p = 0.031). The occurrence of any versus no shock, or of multiple versus single shocks significantly decreased survival at four years, and these differences persisted after adjustment for LVEF. In the LVEF subgroups <35% and <25%, occurrence of multiple versus no shock more than doubled the risk of death. Compared with the most favorable group LVEF > or =35% and no shock, risk in the group multiple shocks and LVEF <35% was increased 16-fold. CONCLUSIONS In defibrillator recipients, shocks act as potent predictors of survival independent of several other risk factors, particularly ejection fraction.

Evaluation of intravenous lidocaine for the termination of sustained monomorphic ventricular tachycardia in patients with coronary artery disease with or without healed myocardial infarction

Prospective evaluations of intravenous lidocaine as therapy for sustained monomorphic ventricular tachycardia (VT) in the absence of acute myocardial infarction are lacking. Lidocaine has been promulgated as first-line therapy in patients with VT, but studies evaluating its efficacy in the electrophysiology laboratory suggest that it has poor effects in terminating or preventing induction of VT. Thus, this study sought to evaluate the clinical effectiveness of lidocaine in 3 cohorts with induced or spontaneous VT. One hundred twenty-eight patients with stable VT, occurring either spontaneously or induced at the time of electrophysiologic study either in the baseline state or at the time of pharmacologic testing, were evaluated. The response rate to lidocaine therapy as manifested by termination of VT was the primary goal of the study. Of these patients, 10 (8%) had termination of VT after lidocaine therapy. There were no significant differences in age, ejection fraction, VT cycle length, and mean dose of lidocaine between responders and 118 nonresponders. There were no serious side effects or adverse events (death, myocardial infarction, angina, or congestive heart failure). Lidocaine, although safe, is ineffective in terminating stable VT not associated with acute myocardial infarction.

Conscious Sedation With Combined Hypnotic Agents for Implantation of Implantable Cardioverter-Defibrillators

OBJECTIVES The objective of this study was to evaluate the feasibility, safety and efficacy of placing implantable cardioverter-defibrillators (ICDs) in the electrophysiology laboratory using conscious sedation with combined hypnotic agents and deep sedation with etomidate. BACKGROUND Implantable cardioverter-defibrillators with transvenous leads permit the use of simplified implantation techniques similar to those used for the insertion of permanent pacemakers. However, implantation of ICDs without general anesthesia has thus far gained limited acceptance. METHODS In 162 patients, conscious sedation during ICD placement was achieved with combined intravenous midazolam, morphine and promethazine (Phenergan). Intravenous etomidate was administered to induce deep sedation for defibrillation threshold testing. First-time implantations were in the prepectoral position (n = 142), but some patients with preexisting devices received abdominal implants (n = 20). The results were compared with those of concurrent patients (n = 56) who received prepectoral implants under propofol anesthesia administered by an attending anesthesiologist. RESULTS The anesthetic protocol was implemented without major intraoperative complications. During deep sedation with etomidate, episodes of apnea, hypoxia or arterial hypotension requiring therapeutic intervention did not occur. During a mean (+/-SD) follow-up period of 257 +/- 140 days (median 227, range 14 to 482), there were, among the 162 patients, a total of two nonsudden cardiac deaths-one 71 days and the other 157 days after the operation. There were two nonsudden deaths in the concurrent control subjects (n = 56)-one 13 days and the other 110 days after the operation. CONCLUSIONS Implantation of ICDs under conscious sedation with combined hypnotic agents and deep sedation with etomidate is a safe and effective procedure with low perioperative morbidity and low long-term complication rates.

Spontaneous Ventricular Tachycardia Treated by Antitachycardia Pacing

: The database of the registry for an implantable cardioverter defibrillator was analyzed to determine the efficacy and safety of antitachycardia pacing for the termination of ventricular tachycardia. In 22,339 episodes treated, termination occurred in 94% and acceleration in only 1.4%.

Cellular Evidence of Reverse Cardiac Remodeling Induced by Cardiac Resynchronization Therapy

Left ventricular assist devices (LVADs) induce reverse cardiac remodeling by reducing myocyte size and collagen deposition. On the other hand, cardiac resynchronization therapy (CRT) induces reverse cardiac remodeling by improving electromechanical synchronization. The clinical and structural changes produced by CRT in failing myocardium are known, but whether these changes are accompanied by reverse cellular remodeling is unknown. A total of 12 patients with chronic heart failure (CHF) who underwent CRT and 15 patients who had LVAD therapy as clinically indicated and 8 healthy controls were compared. Demographics, echocardiographic data, and histologic samples from myocardial biopsies were analyzed and compared among groups. The authors found significant increases in myocyte size, myocardial fibrosis, and inflammation in both CHF groups who underwent CRT or LVAD, compared with healthy controls. After CRT or LVAD therapy, a significant decrease in myocyte size and tumor necrosis factor α (TNF-α) expression compared with healthy controls (P < .05) was found. In the CRT group, 6 of 8 patients demonstrated reduction in myocyte size and interstitial fibrosis. In addition, there was a decrease in myocyte size by 13%, total collagen by 27% and TNF-α by 49% in the CRT group vs 28%, 45%, and 45% in the LVAD group. CRT produces cellular reverse remodeling in failing human hearts that are comparable with those produced by LVAD therapy.

Therapy of Sustained Ventricular Arrhythmias With Amiodarone: Prediction of Efficacy With Serial Electrophysiologic Studies.

Background: Programmed electrical stimulation early during amiodarone therapy has poor prognostic capabilities; and persistent inducibility has been associated with a favorable outcome in a majority of patients. These observations result from studies that differed significantly in methodology. Methods and Results: The authors prospectively enrolled 121 patients in a standardized amiodarone dosing protocol in which amiodarone was the only antiarrhythmic agent. Electrophysiologic testing was done after 2 and 6 weeks to determine noninducibility, predictive value, and the significance of drug-induced prolongation of tachycardia cycle length. The mean age of the patients in the study was 63.2 ± 11.5 years, and their ejection fraction was 32.8 ± 11.9%. Coronary artery disease was present in 103 (85%). At 2 weeks 17 patients (14%) were no longer inducible, whereas 101 patients (86%) remained inducible. Patients in these groups were similar in age and ejection fraction. During follow-up evaluation, recurrences (35% vs 24%; P =.44) and sudden death (12% vs 13.5%) were similar in the two groups. Thirty-five of 95 patients (32%) with sustained monomorphic ventricular tachycardia had more than 100 ms prolongation of their cycle length, which was hemodynamically well tolerated (partial response), but 60 did not (nonresponse). Patients with a partial response were older (66.5 vs 61.1 years; P =.02) and had longer QRS durations (143.2 vs 129.4 ms; P =.03). They also had increased recurrences (37% vs 17%; P =.01) and more sudden deaths (23% vs 8%; P =.02). At 6 weeks 11 of 76 patients studied were noninducible. They had a lower recurrence rate than those who remained inducible (8% vs 27%; P =.02) but a similar number of sudden deaths (8% vs 16%; P =.27). Thirty-two patients partially responded, and 31 patients did not respond. During follow-up examination these two groups had a similar number of recurrences (25% vs 29%; P =.76) and sudden deaths (16% vs 16%). Conclusions: Noninducibility at 2 or 6 weeks of amiodarone therapy did not identify patients at low risk of sudden death. In inducible patients, tachycardia cycle length prolongation, even when well tolerated, was not a marker for favorable outcome. Electrophysiologically guided therapy. therefore. offers little benefit over empiric amiodarone. Conclusions: Noninducibility at 2 or 6 weeks of amiodarone therapy did not identify patients at low risk of sudden death. In inducible patients, tachycardia cycle length prolongation, even when well tolerated, was not a marker for favorable outcome. Electrophysiologically guided therapy. therefore. offers little benefit over empiric amiodarone.

Characterization of spontaneous recurrent ventricular arrhythmias detected by electrogram-storing defibrillators in sudden cardiac death survivors with no inducible ventricular arrhythmias at baseline electrophysiologic testing

This retrospective study characterized the recurring ventricular arrhythmias with an electrogram-storing defibrillator in survivors of sudden cardiac death who had no inducible sustained ventricular arrhythmias at baseline electrophysiologic testing (EPS). The study group was composed of 24 selected patients with documented ventricular fibrillation (VF) without need of revascularization or chronic antiarrhythmic therapy. The EPS protocol usually consisted of three extrastimuli at two drive cycles at two right ventricular sites. Nonischemic cardiomyopathy was the most frequent structural abnormality (n = 11) followed by coronary artery disease (n = 7). The mean ejection fraction was 0.37 +/- 0.13. Cardiac status did not appear to change during a mean follow-up period of 16.4 +/- 12.5 months, and eight (33%) patients received appropriate shocks in that time period. On the basis of intracardiac electrograms, 7 (88%) patients experienced VF and 1 (12%) patient had ventricular tachycardia as the first recurring arrhythmia. Four patients had additional recurrences and all were VF episodes. VF was usually present from the onset of the arrhythmia. In addition, 9 (38%) patients had nonsustained ventricular arrhythmias that were solely VF in 6 (67%). In conclusion, VF of sudden onset was the most frequent recurring sustained ventricular arrhythmia in this group.

Incubation Alone Is Adequate as a Culturing Technique for Cardiac Rhythm Management Devices

ABSTRACT There exist no standardized methods for culturing cardiac rhythm management devices. To identify the most optimal culturing method, we compared various techniques that comprise vortex, sonication, and incubation or combinations thereof. Incubation alone yielded bacterial colony counts similar to those of other culturing combinations and is the least labor-intensive.

Usefulness of Holter monitoring in predicting efficacy of amiodarone therapy for sustained ventricular tachycardia associated with coronary artery disease

The ability of Holter monitoring to predict clinical events during amiodarone therapy was evaluated in 83 patients with coronary artery disease and inducible monomorphic ventricular tachycardia. Sixty-four patients (77%) had significant ventricular ectopy activity (> or = 10 ventricular premature complexes [VPCs]/hour) at baseline, and 19 (23%) did not; patients were similar in age (63 and 65 years, respectively; p = 0.24) and ejection fraction (31 and 32%, respectively; p = 0.75). Over a mean of 23 +/- 17 months, there was no difference in arrhythmia recurrence (33 and 26%; p = 0.89) or sudden death (16 and 20%; p = 0.94) in patients with and without significant ectopy, respectively. In patients with significant ectopy, amiodarone decreased VPC frequency from baseline to 2 weeks, but not from 2 to 6 weeks. Forty-two patients had > 85% reduction in ectopy at 2 weeks; 20 patients did not. However, this reduction of simple VPCs did not predict a decrease in arrhythmic recurrence (29 vs 40%; p = 0.59) nor sudden death (25 vs 11%; p = 0.56) in patients with and without VPC suppression, respectively. Forty-five patients had Holter monitoring at 6 weeks. Twenty-one patients (47%) had > 95% suppression of ectopy, and 24 did not. Neither the recurrence (38 vs 38%; p = 0.54) nor sudden death (33 vs 13%; p = 0.45) rate was predicted by the degree of VPC suppression. Amiodarone is a powerful suppressant of VPCs, but Holter suppression of this ectopic activity is not predictive of clinical outcome.