Right Ventricular (RV) Pacing in Early Post-operative Continuous Flow Left Ventricular Assist Device (LVAD)

• Post-operative need for hemodynamic / respiratory support [ Time Frame: 14 days ] [ Designated as safety issue: Yes ]
  To determine whether continuous RV pacing reduces the need for inotropic / vasoactive agents, mechanical ventilation, or other circulatory support in the early post-operative period. Measured by the number of hemodynamic and respiratory support interventions and duration of those interventions.
• Right ventricular function [ Time Frame: 14 days ] [ Designated as safety issue: Yes ]
  To determine whether continuous RV pacing improves invasive and non-invasive measures of RV function in the early period post-LVAD implantation. Measured by Pulmonary Artery catheter measures of intra-cardiac pressures and cardiac output in the ICU setting and by qualitative and quantitative Echocardiographic measures of RV function during the hospital course.
• Functional capacity and symptoms [ Time Frame: 14 days ] [ Designated as safety issue: Yes ]
  To determine whether continuous RV pacing improves functional capacity and symptoms as measured by six minute walk test and symptoms questionnaires in the early post-LVAD implantation period.

• Post-operative need for hemodynamic / respiratory support [ Time Frame: 14 days ] [ Designated as safety issue: Yes ]
  To determine whether continuous RV pacing reduces the need for inotropic / vasoactive agents, mechanical ventilation, or other circulatory support in the early post-operative period. Measured by the number of hemodynamic and respiratory support interventions and duration of those interventions.
• Right ventricular function [ Time Frame: 14 days ] [ Designated as safety issue: Yes ]
  To determine whether continuous RV pacing improves invasive and non-invasive measures of RV function in the early period post-LVAD implantation. Measured by PA catheter measures of intra-cardiac pressures and cardiac output in the ICU setting and by qualitative and quantitative Echocardiographic measures of RV function during the hospital course.
• Functional capacity and symptoms [ Time Frame: 14 days ] [ Designated as safety issue: Yes ]
  To determine whether continuous RV pacing improves functional capacity and symptoms as measured by six minute walk test and symptoms questionnaires in the early post-LVAD implantation period.

Continuous right ventricular (RV) pacing demonstrates harm in patients with normal left ventricular (LV) function as well as in patients with cardiomyopathy and clinical heart failure. However, little is known about RV pacing in patients with advanced heart failure treated with an implantable left ventricular assist device (LVAD). The univentricular support provided by contemporary continuous flow LVAD's has improved outcomes for many advanced heart failure patients, yet the incidence of RV failure in the early post-operative period following implantation is associated with significantly reduced survival and increased length of stay. Acute LVAD unloading of the left ventricle has adverse effects on RV shape and size that contribute to post-operative RV failure. By promoting RV synchrony, RV overdrive pacing may counteract these adverse mechanical alterations, improving RV systolic function and ultimately LVAD function.

The investigators will recruit all patients referred for an implantable, continuous flow LVAD at Duke University Medical Center who have an existing implantable dual-chamber cardioverter-defibrillator. Patients will be prospectively randomized into two cohorts to compare continuous right ventricular pacing vs. native ventricular conduction at equivalent heart rates. Multiple clinical outcomes will be examined over a two week period post-operatively including invasive hemodynamics, vasoactive medication use, end-organ function, RV function by Echocardiography as well as patient symptoms and functional status.

• Device: Implantable Cardioverter-Defibrillator (subject's pre-existing ICD)
  Pacing parameters set to AAI 90
• Device: Implantable Cardioverter-Defibrillator (subject's pre-existing ICD)
  Pacing parameters set to DDD 90-100

• Placebo Comparator: Native Conduction
  Devices will be programmed to continuous atrial pacing at an AAI (atrial inhibited pacing) setting with base rate 90 bpm. Patients will not receive ventricular pacing.
  Intervention: Device: Implantable Cardioverter-Defibrillator (subject's pre-existing ICD)
• Experimental: Continuous RV Pacing
  Devices will be programmed to continuous dual chamber pacing at a DDD (dual chamber dual pacing) setting with base rate ≥ 90 bpm (not to exceed 100 bpm) to achieve a majority (>80%) of paced right ventricular beats
  Intervention: Device: Implantable Cardioverter-Defibrillator (subject's pre-existing ICD)

Inclusion Criteria:

• Age ≥ 18 years old, both men and women
• Existing implantable cardioverter-defibrillator (ICD)
• Referred for implantation of a continuous flow LVAD

Exclusion Criteria:

• Permanent left ventricular epicardial defibrillator in place
• Congenital heart disease with single ventricle physiology
• Right ventricular assist device (RVAD) in place
• Existing pacing indication