Effect of Cardiac Resynchronization Therapy (CRT) on Left Ventricular Assist Device (LVAD) Function

Certain patients with congestive heart failure are treated both by implantation of an LVAD, as well as implantation with a biventricular pacemaker. Both of these devices, individually, have been shown to improve the health of patients with heart failure. However, only a small number of patients have both an LVAD and a biventricular pacemaker at the same time. Pacemakers have many different settings. However, there is little data to inform physicians which of these different settings is best for the flow of an LVAD. This study is evaluating patients who have both a biventricular pacemaker and an LVAD. Investigators will operate the pacemaker at multiple different settings and monitor the LVAD's function to determine which, if any, setting is best for the LVAD's flow.