Selective site ventricular pacing.
OBJECTIVE
The traditional site for ventricular pacing, the right ventricular apex, produces an abnormal pattern of ventricular depolarization and there is growing evidence that pacing from this site is associated with adverse functional and structural changes in the left ventricle. This is manifest clinically as an increased morbidity and mortality. These observations have fuelled interest in pacing at sites alternative to the right ventricular apex. In this article, we review the evidence for selective site pacing, focusing mainly on the right ventricular outflow tract.


RESULTS
Data are conflicting on the acute and medium-term effects of right ventricular outflow tract pacing. Although a recent meta-analysis has suggested acute benefit from pacing at this site, the data are confounded by poor definition of the outflow tract and the non-randomized nature of most trials. There is a need for standardization of nomenclature and better definition of non-apical sites. Long-term data on chronic pacing are limited, with two studies showing equivalency between apical and outflow tract pacing. In another two studies, right ventricular outflow tract pacing was associated with improved ejection fraction.


CONCLUSIONS
Selective site pacing holds promise in attempting to reduce the problems associated with chronic ventricular pacing. Large, prospective, randomized control trials are needed.
McGavigan
Andrew D
AD
Department of Cardiology, The Royal Melbourne Hospital, Victoria 3050, Australia.
Mond
Harry G
HG
D000818:Animals; D002036:Bundle of His / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D017180:Tachycardia, Ventricular / Q000628:therapy*