Subsidiary pacemaker function in complete heart block after His-bundle ablation.

Abstract

To investigate the electrophysiological properties of ventricular impulse formation after His-bundle ablation in 11 patients, incremental ventricular overdrive stimulation studies were performed. The studies, which were spread over a follow-up period of up to 601 days, were carried out invasively with temporary leads as well as noninvasively with the implanted pacemakers and chest wall inhibition. The overdrive pacing rate was increased in steps of 10 beats/min, and the pacing duration was 2 minutes at each level. (Circulation 1988;78:893-898) S ince its introduction in humans,' 2 closed-chest ablation of the atrioventricular conduction system has become a routine therapeutic alternative for the treatment of supraventricular tachycardias unresponsive to medical treatment. The purpose of the procedure is to create complete heart block to prevent rapid ventricular response during supraventricular tachycardias. In the setting of complete heart block, overdrive suppression of subsidiary pacemakers is abolished and ventricular tissue assumes the function of impulse formation initiating the activation of the heart. However, because the rate of the newly established subsidiary rhythm and its adaptation during physical activity usually does not meet the demand, the majority of these patients require permanent ventricular pacing, and some will become completely pacing dependent.

Is Pacemaker Deactivation at the End of Life Unique?: A Case Study and Ethical Analysis

“…9 Others label patients as pacemaker dependent only if pacemaker deactivation results in asystole in the absence of an underlying escape rhythm. 10 There is also uncertainty as to how the presence of a native heart rhythm should be determined. Some experts have recommended decreasing the pacing rhythm abruptly to 30 or 40 beats per minute to allow an underlying escape rhythm to be observed.…”

Evaluation of pacemaker dependence in patients on ablate and pace therapy for atrial fibrillation

“…It is, however, a palliative procedure and gives rise to several problems, a major one being the induction of PM dependence. Earlier studies [14][15][16] downplayed this problem, demonstrating the presence of a valid escape rhythm in the vast majority of patients who had undergone AV node ablation. More recently, however, the ample case records collected by Curtis et al 2 revealed that an escape rhythm was present in only 67% of the 156 patients included in the register of the Ablate and Pace Trial and that an escape rhythm with a rate .40 bpm was observed in only 31%.…”