Dennis W.X. Zhu

Radiofrequency catheter ablation for management of symptomatic ventricular ectopic activity

OBJECTIVES This study assessed the useful role of intracardiac mapping and radiofrequency catheter ablation in eliminating drug-refractory monomorphic ventricular ectopic beats in severely symptomatic patients. BACKGROUND Ventricular ectopic activity is commonly encountered in clinical practice. Usually, it is not associated with life-threatening consequences in the absence of significant structural heart disease. However, frequent ventricular ectopic beats can be extremely symptomatic and even incapacitating in some patients. Currently, reassurance and pharmacologic therapy are the mainstays of treatment. There has been little information on the use of catheter ablation in such patients. METHODS Ten patients with frequent and severely symptomatic monomorphic ventricular ectopic beats were selected from three tertiary care centers. The mean frequency +/- SD of ventricular ectopic activity was 1,065 +/- 631 beats/h (range 280 to 2,094) as documented by baseline 24-h ambulatory electrocardiographic (ECG) monitoring. No other spontaneous arrhythmias were documented. These patients had previously been unable to tolerate or had been unsuccessfully treated with a mean of 5 +/- 3 antiarrhythmic drugs. The site of origin of ventricular ectopic activity was accurately mapped by using earliest endocardial activation time during ectopic activity or pace mapping, or both. RESULTS During electrophysiologic study, no patient had inducible ventricular tachycardia. The ectopic focus was located in the right ventricular outflow tract in nine patients and in the left ventricular posteroseptal region in one patient. Frequent ventricular ectopic beats were successfully eliminated by catheter-delivered radiofrequency energy in all 10 patients. The mean number of radiofrequency applications was 2.6 +/- 1.3 (range 1 to 5). No complications were encountered. During a mean follow-up period of 10 +/- 4 months, no patient had a recurrence of symptomatic ectopic activity, and 24-h ambulatory ECG monitoring showed that the frequency of ventricular ectopic activity was 0 beat/h in seven patients, 1 beat/h in two patients and 2 beats/h in one patient. CONCLUSIONS Radiofrequency catheter ablation can be successfully used to eliminate monomorphic ventricular ectopic activity. It may therefore be a reasonable alternative for the treatment of severely symptomatic, drug-resistant monomorphic ventricular ectopic activity in patients without significant structural heart disease.

Atrial septal pacing: a method for pacing both atria simultaneously.

By pacing both atria simultaneously, one could reliably predict and optimize left‐sided AV timing without concern for IACT. With synchronous depolarization of the atria, reentrant arrhythmias might be suppressed. We studied four male patients (73 ± 3 years) with paroxysmal atrial fibrillation and symptomatic bradyarrhythmias using TEE and fluoroscopy as guides; a standard active fixation screw‐in lead (Medtronic model #4058) was attached to the interatrial septum and a standard tined lead was placed in the ventricle. The generators were Medtronic model 7960. The baseline ECG was compared to the paced ECG and the conduction time were measured to the high right atrium, distal coronary sinus and atrial septum in normal sinus rhytbm, atrial septal pacing, and AAT pacing. On the surface ECG, no acceleration or delay in A V conduction was noted during AAI pacing from the interatrial septum as compared with normal sinus rhythm. The mean interatrial conduction time for all 4 patients was 106 ± 2 ms; the interatrial conduction time measured during AAT pacing utilizing the atrial septal pacing lead was 97 ± 4 ms (P = NS). During atrial septal pacing, the mean conduction time to the high right atrium was 53 ± 2 ms. The mean conduction time to the lateral left atrium during atrial septal pacing, was likewise 53 ± 2 ms. We conclude that it is possible to pace both atria simultaneously from a single site using a standard active fixation lead guided by TEE and fluoroscopy. Such a pacing system allows accurate timing of the left‐sided AV delay.

The Value of Electrophysiology Study and Prophylactic Implantation of Cardioverter Defibrillator in Patients with Hypertrophic Cardiomyopathy

Fifty‐three consecutive patients with hypertrophic cardiomyopathy (HCM) and no history of sudden death underwent electrophysiology (EP) study. Sustained polymorphic ventricular tachycardia (VT) or ventricular fibrillation (VF) was induced in 19 patients (35%). Patients with prior syncope or near syncope had a higher incidence of VT/VF inducibility. An implantable cardioverter defibrillator (ICD) was placed in 14 of the 19 patients. Of the remaining 5 patients with inducible VT/VF, three refused ICD implantation, while two underwent septal myectomy and VT/VF was no longer inducible afier the operation. None of the patients received antiarrhythmic drugs. During a mean follow‐up period of 47 ± 31 (2–117) months, no events occurred in the 34 patients with negative EP study. Three events occurred among the 19 patients with inducible VT/VF. One patient died suddenly, one developed wide complex tachycardia which required resuscitation, and one patient received an appropriate ICD shock. In conclusion, sustained polymorphic VT/VF was inducible in about one‐third of patients with HCM. Noninducibility of VT/VF appeared to predict a favorable prognosis. Although the overall event rate was low in patients with inducible VT/VF, prophylactic ICD implantation in patients with multiple risk factors may be appropriate.

Subclavian venogram as a guide to lead implantation

Recent reports have raised doubts regarding the safety and efficacy of the blind subclavian venipuncture technique for intra‐cardiac lead implantation. To permit a more lateral entry, we used a simple subclavian venogram performed through the brachial vein of the ipsilateral arm of 22 consecutive unselected patients undergoing had implantation (19 permanent pacemakers and 3 intracardiac defibriUators). A total of 35 leads were implanted (31 left pectoral and 4 right pectoral). Lead insertion by venogram technique was used successfully in all patients. Two inconsequential arterial punctures occurred. There were no pneumotho‐races, infections, or other complications. Lateral placement should facilitate lead manipulation and minimize “subclavian crush.” The method of ipsilateral venogram guided lead insertion appears to be safe and reliable and deserves consideration in patients who require permanent lead placement via the subclavian vein approach.

Case Report: Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in a Patient with Heart Transplantation

Ten years after orthotopic cardiac transplantation, a 56-year-old man developed recurrent presyncope and syncope. A 24-hour ambulatory electrocardiographic recording did not document significant arrhythmic events. A head-up tilt table test was negative. An electrophysiologic study revealed dual atrioventricular (AV) nodal physiology and inducible typical atrioventricular nodal reentrant tachycardia (AVNRT). The patient became hypotensive and presyncopal during AVNRT. Radiofrequency (RF) catheter ablation successfully eliminated AVNRT without complications. The patient remained free of symptoms at nine months follow-up.

Perioperative management of anticoagulation in patients on warfarin therapy undergoing surgery for cardiac implantable electronic devices

Many patients on chronic warfarin therapy are undergoing surgery for permanent pacemakers and implantable defibrillators, collectively known as cardiac implantable electronic device (CIED). The perioperative management of anticoagulation in these patients is a challenging clinical situation that requires balance between the risk of acute thrombosis and perioperative hemorrhage. This issue however, is inadequately addressed in the guidelines published by professional organizations. Increasing evidence suggests that temporarily interrupting anticoagulation is associated with a small but real thromboembolic risk, whereas cessation of warfarin with heparin bridging anticoagulation frequently leads to a higher incidence of pocket hematoma. Continuing warfarin with a therapeutic international normalized ratio appears to be a safe and cost‐effective approach for CIED surgery in most patients with moderate to high thromboembolic risk. An algorithm is proposed for the practical management of anticoagulation and antiplatelet therapy in these patients during the perioperative period.