Right ventricular pacing and atrial fibrillation: villain, victim, or just misunderstood?

Abstract

Right ventricular (RV) pacing enters its sixth decade facing an uncertain future and an increasingly dissatisfied audience. This surprising reversal of fortune would not have been anticipated by the preceding 40 years, since Furman and Schwedel demonstrated the feasibility of transvenous endocardial pacing from the RV.1 The prevention of recurrent syncope and death due to ventricular asystole, the most lethal of all heart rhythm disturbances, using RV pacing stands as one of the greatest medical achievements of the 20th century. Protection against ventricular asystole remains the primary purpose of pacemaker therapy. This fact is reflected at two levels of concern for safety (i) design principles of pacing systems, (ii) physician choice of pacing system for the individual patient. All pacing systems which include a ventricular lead operate on the defining principle that ventricular pacing (VP) is guaranteed on every cardiac cycle if needed. Consequently, dual-chamber timing cycle operation is configured to meet this goal by scheduling a VP stimulus at the end of the pacemaker atrioventricular (AV) interval (pAVI). Additional countermeasures are taken to prevent inappropriate inhibition of the scheduled VP during the pAVI. All other timing considerations are secondary to rules for maintaining VP. From the physician's perspective of patient safety, VP capability is almost universally mandatory, even though many patients with sinus node disease (SND) are safely treated with atrial-only pacing.2 Nominal pAVIs are <200 ms on the physiologically imprecise premise that approximation of the normal PR interval with RV pacing duplicates four-chamber … *Corresponding author. Tel: +1 857 307 1940, Fax: +1 587 307 1944, Email: mosweeney{at}partners.org