"Dialing-in" cardiac resynchronization therapy: overcoming constraints of the coronary venous anatomy.

Several reports have indicated that left ventricular (LV) lead placement at an optimal anatomic pacing site is a critical determinant of outcome of cardiac resynchronization therapy (CRT). Selecting the 'right' patient for CRT but stimulating the 'wrong' site remains an important cause for the high incidence of non-responders to CRT. This technical report (a) recognizes the variance in the coronary venous anatomy and its impact on the final LV lead position, (b) emphasizes the importance of the ventricular electrical activation pattern and its alteration with RV and LV pacing and (c) proposes a novel method to "dial-in" the site for right ventricular (RV) pacing to maximize the electrical separation from the left ventricular lead, rather than taking the first acceptable RV site in the apex or the apico-septal region. This electrical distancing of the leads will potentially improve the mechanics of ventricular contraction and the flexibility of RV-LV optimization.