Cardiac Resynchronization Therapy: Lead Positioning and Technical Advances

Cardiac resynchronization therapy (CRT) is a therapeutic option for heart failure patients with a severely reduced left ventricular ejection fraction and left bundle branch block (Cleland et al., 2001). Ventricular resynchronization is achieved by biventricular pacing, usually via electrodes in the right ventricular apex and a left ventricular (LV) electrode positioned in a coronary vein. About one third of implanted patients do not respond to CRT (Derval et al., 2010). In order to reduce the percentage of non-responders, several strategies have been developed. They include optimization of patient selection, device programming as well as LV lead location. In cardiomyopathy with left bundle branch block, the lateral wall is the site of latest activation and should be the optimal location for LV pacing. Therefore, standard implantation sites for LV leads are lateral or posterolateral branches of the coronary sinus. Congruent to these pathophysiological findings, Butter et al. demonstrated a superiority of lateral wall pacing versus anterior wall pacing in CRT (Butter et al., 2001). However, a more detailed look at optimal pacing locations might be required to increase the effect of CRT and decrease non-responder rates. Different imaging modalities have been used to both identify optimal pacing sites as well as to plan LV lead implantation.