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

Cardiac resynchronization therapy (CRT) with a biventricular pacemaker has been well-validated to improve symptoms and reduce death in select patients with heart failure. In healthy adults, the two chambers of the heart which pump blood throughout the body (the left and right ventricles) activate and contract together in synchronous fashion. In certain patients with heart failure (specifically, those with a reduced ejection fraction), the left and right ventricles no longer activate and contract synchronously. CRT restores ventricular synchrony by simultaneously activating the left (LV) and right ventricles (RV) with electrical pacing.

Left ventricular assist devices (LVADs) are used to provide mechanical support to patients with more advanced, often end-stage, heart failure. In these cases, the heart's ventricles function so poorly that even despite all standard therapies (including CRT), patients experience symptoms of congestive heart failure even at rest. The LVAD suctions blood from the ventricle and propels it into the aorta, offloading the ventricle and assisting its function.

Due to the similar reasons for using each therapy, a number of patients already possess a biventricular pacemaker at the time of LVAD implantation. Individually, each intervention is known to improve both patient survival and functional status. However, there is sparse data to evaluate the effectiveness of using both devices simultaneously. Specifically, no data is yet available assessing the effect of CRT on the functional parameters of the LVAD.

This protocol will operate the biventricular pacemaker at various settings and assess for changes in the LVAD's function in response to those settings. "Fine-tuning" and identifying the ideal the pacemaker settings will maximize clinical benefit in patients with both devices.