Michael Eldar

Combined use of beta-adrenergic blocking agents and long-term cardiac pacing for patients with the long QT syndrome

OBJECTIVEnThe objective of this study was to review our current experience using a combination of beta-adrenergic blocking agents and long-term cardiac pacing to treat patients with the idiopathic long QT syndrome.nnnBACKGROUNDnPatients with the idiopathic long QT syndrome are at high risk for sudden cardiac death. Before combination therapy, 20 of the 21 study patients experienced either cardiac arrest (n = 8) or syncope (n = 18) and 11 had documented polymorphous ventricular tachycardia. Nine of these patients had not responded to isolated beta-blocker therapy and five had not responded to isolated left cervicothoracic sympathectomy.nnnMETHODnAll patients were treated with combined beta-blocker therapy and long-term cardiac pacing at a rate designed to normalize the QT interval.nnnRESULTSnCardiac pacing at rates of 70 to 125 beats/min resulted in shortening of the QT and corrected QT (QTc) intervals from 517 +/- 78 and 541 +/- 62 ms to 404 +/- 37 and 479 +/- 41 ms, respectively. The mean follow-up interval after institution of pacing was 55 +/- 45 months. The only sudden death occurred in a patient who had discontinued beta-blocker therapy. Syncope occurred in four patients, two of whom had interrupted pacemaker function due to lead fracture. Pacemaker problems, partly attributable to the specific rate required for QT interval shortening and to avoidance of T wave sensing, were relatively common. No patient who continued the combination therapy died, but 10% of these patients had a recurrence of symptoms.nnnCONCLUSIONSnCombination therapy with a beta-blocker and cardiac pacing appears to be a highly effective primary therapy for symptomatic patients with the long QT syndrome and to provide excellent adjunctive therapy for patients who require insertion of an automatic internal defibrillator.

Long-Term Follow-Up of Patients With Long-QT Syndrome Treated With β-Blockers and Continuous Pacing

BACKGROUNDnThe long-QT syndrome is associated with sudden cardiac death. Combination of beta-blocker and pacing therapy has been proposed for treatment of drug-resistant patients. The purpose of this study was to summarize our long-term experience with combined therapy in patients with long-QT syndrome.nnnMETHODS AND RESULTSnA total of 37 patients with idiopathic long-QT syndrome were treated with combined therapy consisting of continuous cardiac pacing and maximally tolerated beta-blocker therapy and followed up for 6.3+/-4. 6 years (mean+/-SD). The group consisted of 32 female and 5 male patients with a mean age of 31.6 years. The mean paced rate was 82+/-7 bpm (range, 60 to 100 bpm). On follow-up, recurrent symptoms caused by pacemaker malfunction were documented in 3 patients. Four patients died during the follow-up period: 2 adolescents stopped beta-blocker therapy, 1 patient died suddenly while treated with combined therapy, and 1 patient died of unrelated causes. In addition, 3 patients had resuscitated cardiac arrest while on combined therapy, and 1 patient had repeated, appropriate implantable cardioverter-defibrillator discharges on follow-up.nnnCONCLUSIONSnBecause 28 of 37 patients remain without symptoms with beta-blocker therapy and continuous pacing, combined therapy appears to provide reasonable, long-term control for this high-risk group. However, the incidence of sudden death and aborted sudden death (24% in all patients and 17% in compliant patients) strongly suggests the use of a back-up defibrillator, particularly in noncompliant adolescent patients. Implantable cardioverter-defibrillator therapy, however, may be associated with recurrent shocks in susceptible patients.

Sudden cardiac death and polymorphous ventricular tachycardia in pationts with normal QT intervals and normal systolic cardiac function

This study delineates the clinical spectrum of 15 patients with polymorphic ventricular tachycardia and normal QT intervals in the absence of apparent structural heart disease, adverse drug effects, or electrolyte disturbances. Patients presented with either palpitations (n = 2), presyncope (n = 5), syncope (n = 4), no symptoms (n = 1), or aborted sudden death (n = 3). Mean age was 41 years (range 20 to 64), and mean follow-up 38 months (range 4 to 109). Left ventricular function was normal as determined by either echocardiogram (n = 9) or left ventriculography (n = 9). Episodes of polymorphic ventricular tachycardia (VT) were analyzed in terms of the preceding interval, and the relation of the initiating coupling interval to the QT interval (coupling interval/QT interval = polymorphic VT index). The mean QT for the group as a whole was 0.41 +/- 0.02 second. Patients could be separated into 3 distinct groups. Four patients had polymorphic VT reproducibly induced by exercise and initiated by late-coupled beats (mean polymorphic VT index 1.27 +/- 0.21). Isoproterenol induced polymorphic VT in 3 of 4 patients, and all 4 responded to chronic beta blockade. Two patients had polymorphic VT during episodes of coronary artery spasm, and both responded to calcium channel blockade. Polymorphic VT unrelated to exertion or coronary vasospasm occurred in 9 patients. Tachycardia onset was initiated by closely coupled beats (mean polymorphic VT index 0.95 +/- 0.16), and was preceded by a pause in 4 patients, and no pause in 5 patients. Sudden death occurred in 5 of 9 patients with the shortest polymorphic VT indexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheter Atrioventricular Junctional Ablation in Patients with Accessory Pathways

Seven patients with accessory pathway and symptomatic alrioventricular reciprocating tachycardia underwent catheter ablution of the atrioventricular junction (AVJ). Four patients had the Wolff‐Park inson White syndrome, two had concealed left free‐wall accessory pathways, and one patient had a nodoventriculor connection. All patients failed multiple antiarrhythmic drugs and one failed attempted surgical ablation of a posteroseptal accessory pathway. Chronic interruption of atrioventricular node‐His conduction was achieved in all patients. Over a mean follow‐up period of 21 ± 14 months, four patients remained asymptomatic without antiarrhythmic therapy. One patient developed atrial fibrillation after magnet application to her VVI pacemaker, another developed atrial gutter, and a third had nonparoxysmal sinus or atrial tachycardia. Two patients required chronic quinidine therapy. Two patients with concealed accessory pathways had pacemaker‐mediated tachycardia which was controlled by pacemaker reprogramming. Atrioventricular junctional ablation in patients with accessory pathways proved elective in that all are currently controlled without need for surgical intervention. On follow‐up, a relatively high incidence of atrial arrhythmias requiring antiarrhythmic therapy was found.

Procainamide-induced incessant supraventricular tachycardia in the Wolff-Parkinson-White syndrome.

A patient with the Wolff‐Parkinson‐While syndrome presented with incessant orthodromic atrioventricular tachycardia following initiation of procainamide therapy. This finding was repeatedly documented both clinically as well as during electrophysiologic testing. Escape atrial complexes, which occurred following junctional premature complexes, failed to initiate tachycardia in the control state but tachycardia was always reinitiated by an identical escape sequence after procainamide. In addition, the tachycardia persisted and was repeatedly spontaneously reinitiated for prolonged periods after procainamide. The pro‐arrhythmic effects of procainamide may be explained on the basis of both its vagolytic action on the atrioventricular node as well as by prolongation of refractoriness in the accessory pathway. These observations add to the literature on pro‐arrhythmic effects of commonly used antiarrhythmic drugs.

Ventricular Tachycardia Radiofrequency Ablation with Extracorporeal Membrane Oxygenation

Introduction: Cases of ventricular tachycardia (TV) with hemodynamic compromise present a challenge in achieving non-inducibility by radiofrequency catheter ablation (RFCA). We report our experience of VT RFCA facilitated by elective mechanical circulatory support. nMethods and results: Five patients with hemodynamically unstable, recurrent ventricular arrhythmias that were unresponsive to medical therapy underwent extracorporeal membrane oxygenation (ECMO) assisted RFCA of scar related VT. All underwent RFCA under general anesthesia and were connected to an ECMO circuit maintained at minimum flow of 1.5 L /min. In case of VT or VF the blood flow of the ECMO circuit was increased to 4 L/min to allow hemodynamic stability and adequate systemic organ perfusion. A total of 8 VTs were observed. In 4 cases, we mapped during VT the critical isthmus was found and ablated. Four VTs were targeted by substrate mapping only. Complete success, defined as non-inducibility with aggressive program stimulation of any VT, was achieved in 4 patients. In a single patient, a non-clinical VT was still inducible. He died of septic shock 24 hour after the procedure. The remaining 4 were free of ventricular arrhythmia as proven by implanted defibrillator interrogation, over a median follow up of 16 months. nConclusion: ECMO implantation for VTRFCA is safe and assists in reaching the desired endpoint of noninducibility. This approach should be considered in high risk patients who may not otherwise tolerate such procedures.