His bundle pacing: Hemodynamics and clinical outcomes

From 1993 to 2009, nearly 2.9 million pacemakers were implanted in the United States; the majority of which were dual-chamber pacemakers. One of the major physiologic advantages of dual-chamber pacing over singlechamber ventricular pacing is atrioventricular synchrony, which prevents the pacemaker syndrome. However, patients who are pacemaker dependent or use right ventricle (RV) apical pacing more than 40% of the time are at a risk of developing heart failure from electromechanical dyssynchrony. Studies have also shown that RV pacing results in nonphysiological activation of the left ventricle, leading to adverse clinical outcomes. Hence, alternative pacing sites, including the RV outflow tract, the high-RV septal region, bi-ventricular pacing, or His bundle pacing, have been explored for a better physiological electromechanical coupling of the ventricles. Although His bundle pacing has gained attention due to favorable data and clinical outcomes, it has not gained widespread acceptance into clinical practice. Hence, we aim to review the current experience with His bundle pacing and its clinical implications in this article.