Inter‐ and Intravein Differences in Cardiac Output with Cardiac Resynchronization Pacing using a Multipolar LV Pacing Lead

BACKGROUND: Quadripolar left ventricular pacing leads permit a variety of pacing configurations from different sites within a coronary vein. There may be advantages to selecting a specific pacing vector. This study examines whether the range of cardiac outputs obtained at cardiac resynchronization therapy (CRT) implantation is greater between different poles within a vein, or greater between two different veins. METHODS AND RESULTS: The cardiac index (CI, L/min/m(2) ) was measured during CRT implantation using a noninvasive cardiac output monitor (NICOM™, Cheetah Medical Inc., Newton Center, MA, USA) and a quadripolar left ventricle (LV) lead, in 22 patients with sinus rhythm. CI was recorded during right atrial-biventricular pacing at 70/min with fixed atrioventricular and ventriculo-ventricular delay, from each LV electrode in one vein, and then from an alternate vein. Phrenic nerve stimulation (PNS) occurred in nine of 15 posterior and three of 21 anterior veins (P = 0.005). At least one electrode in each vein had no PNS. The mean (standard deviation [SD]) difference between best and worst CI within any one vein was 13.1% (±9%). The mean (SD) difference between the best CI in one vein compared to the other was 9.8% (±8%; P = 0.043). In 16 of 22 patients, the range of CI was greater between poles within one vein, rather than between two veins (best of one vein compared to best from the other). In four of 22 patients, the range was greater between veins (P = 0.0003). CONCLUSION: A greater range of CI is found within a single vein than between two different veins. This finding has implications both for the approach to implant technique and postimplant programming and optimization.