To determine whether survival after permanent ventricular demand (VVI) pacing differs from survival after permanent dual chamber (DVI or DDD) pacing in patients with chronic high degree atrioventricular (AV) block (Mobitz type II or trifascicular block), 132 patients who received a VVI pacemaker (Group 1) and 48 patients who received a DVI or DDD pacemaker (Group 2) were followed up for 1 to 5 years. There was no significant difference in sex distribution, mean age or incidence of coronary heart disease, hypertension, valvular heart disease, diabetes mellitus, stroke or renal failure between Groups 1 and 2. Overall, the predicted cumulative survival rate at 1, 3 and 5 years was 89, 76 and 73%, respectively, for Group 1 and 95, 82 and 70%, respectively, for Group 2. In patients with preexistent congestive heart failure, the predicted cumulative survival rate at 1, 3 and 5 years was 85, 66 and 47%, respectively, for Group 1 (n = 53) and 94, 81 and 69%, respectively, for Group 2 (n = 20). The 5 year predicted cumulative survival rate was significantly lower in Group 1 patients with preexistent congestive heart failure than in Group 2 patients with the same condition (p less than 0.02). There was no significant difference in 5 year cumulative survival rate between Groups 1 and 2 for patients without preexistent congestive heart failure. The results suggest that permanent dual chamber pacing enhances survival to a greater extent than does permanent ventricular demand pacing in patients with high degree AV block and preexistent congestive heart failure.
The dislodgment rate of permanent pacing ventricular and atrial endocardial leads has significantly decreased with the incorporation of tines as a fixation device. In contrast, transvenous manual extraction of chronically implanted endocardial leads is, at times, clinically indicated, particularly when pacemaker system infection is present. The success rate of such extraction attempts for ventricular endocardial leads over the past 5 years was reviewed. Extraction was usually successful (six of seven attempts) in patients with silicone rubber nontined (or short-tined) older ventricular endocardial leads (Group A). However, in patients with newer urethane long-tined ventricular endocardial leads (Group B), extraction was unsuccessful in three of four attempts. Because of entrapment of the distal electrode tip in the right ventricular apex, manual traction of these leads resulted in permanent conductor material stretching with resultant urethane insulator material breakage in the region of the joints with proximal and distal electrodes. The one successful extraction in Group B was technically difficult and appeared to create a significant risk of intracardiac lead separation. This experience indicates that with improved pacemaker lead design decreased lead dislodgment has been obtained at the cost of increased difficulty of ventricular endocardial lead extraction. Such difficulty should be anticipated when a clinical decision is made to attempt to extract the new urethane long-tined ventricular leads.
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