Selected Site Pacing to Avoid Phrenic Nerve Stimulation in Cardiac Resynchronization Patients With Quadripolar Left Ventricular Leads

Cardiac resynchronization (CRT) therapy is well established for treatment of patients with severe heartfailure, reduced left ventricular (LV) function and ventricular dyssynchrony. Roughly 1/3 of CRT patients do not improve after CRT implant. One possible reason is interruption of biventricular pacing. This might be caused by several conditions, including elevated left ventricular (LV) pacing thresholds or presence of phrenic nerve stimulation (PNS). CRT devices with quadripolar LV leads offer 10 LV pacing vectors to choose from. It's the aim of this prospective observational study to investigate efficacy and reliability of cardiac resynchronization therapy (CRT) with quadripolar left ventricular leads. Hypothesis: In more than 90% of patients, who received a CRT system with quadripolar LV lead, at least one acceptable LV lead vector is available.