Ventricular pacing: to pace or not to pace

Abstract

Pacing from the right ventricular apex has been the clinical standard for decades but has recently come into question with a growing trend towards reducing ventricular pacing as much as possible. The earliest devices provided asynchronous ventricular pacing in patients whose indication for pacing was asystolic complete heart block. RV apical pacing was literally the difference between life and death. Over the decades, as technology has advanced allowing the medical community to more closely model normal cardiac physiology, we have seen the progressive introduction of demand function, single-chamber atrial pacing, dual-chamber pacing, dual-chamber rate-modulated pacing, and in the past decade, cardiac resynchronization pacing. During this evolution, it has been noted that pacing from the right ventricular apex, even in the presence of high-grade AV block, may contribute to ventricular dysfunction associated with the disordered ventricular activation sequence associated with the paced left bundle branch block pattern. ‘Pacemaker syndrome’ or the adverse haemodynamics associated with a technically normal pacing system was rarely recognized in the late 1960s when complete heart block was the indication for implantation. Its recognition blossomed in the 1980s with the introduction of dual-chamber pacing systems and an increase in the relative indications for permanent pacing including individuals who only needed pacing on an intermittent basis or whose primary indication for pacing was sinus node dysfunction. Pacemaker syndrome was usually associated with a loss of appropriate atrial transport (atrioventricular synchrony) and was able to be corrected by upgrading a patient with a single-chamber VVI pacing system to a DDD pacing system.1–3 The standard location for the ventricular lead during the first four decades of cardiac pacing was the RV apex. The first generation of DDD pacemakers had limited AV delay programmability such that there was either full ventricular pacing or consistent ventricular fusion. On the … *Corresponding author. Tel: +1 818 493 2900, Fax: +1 818 362 2242, Email: plevine{at}sjm.com