Comparison of right and left ventricular responses to left ventricular assist device support in patients with severe heart failure - A primary role of mechanical unloading underlying reverse remodeling

Background-Left ventricular assist devices (LVAD) reverse ventricular, myoc ardial, and systemic abnormalities characteristic of severe heart failure ( reverse remodeling). The relative contributions of hemodynamic unloading an d normalized biochemical milieu to reverse remodeling are unknown. Methods and Results-Structural and functional characteristics were measured from 53 hearts of patients undergoing transplantation without LVAD support (medical support) and 33 hearts from patients receiving a median of 46 day s of LVAD support (range, 8 to 360 days). Compared with medical support alo ne, patients receiving LVAD support for greater than or equal to 30 days ha d higher central venous pressures (11 +/-6 versus 8 +/-5 mmHg, P=0.04), low er pulmonary artery diastolic pressures (14 +/-9 versus 21 +/-9 mm Hg, P= 0 .01), and higher cardiac outputs (5.1 +/-1.6 versus 3.7 +/-1.0 L/min, P <0. 001). In LVAD versus transplantation hearts, V-30 (ex vivo volume yielding ventricular pressure of 30 min Hg was decreased in the left ventricle (LV) (179 +/- 75 versus 261 +/- 118 mL, P=0.005) but not in the right ventricle (RV) (140 +/- 59 versus 148 +/- 52 mL, P=NS). LV myocyte diameter decreased more significantly after LVAD support (17%, P= 0.05) than in the RV (11%, P=NS). Compared with transplantation, LVAD support increased normalized SER CA2a content in the LV (0.51 +/-0.26 versus 1.04 +/-0.34, P <0.001) but not in the RV (0.48 +/- 34 versus 0.67 +/-0.55, P=NS). Finally, LVAD support i mproved force-frequency relations of isolated superfused LV trabeculae (P=0 .01) but not RV trabeculae. Conclusions-Reduction of hemodynamic load is a primary factor underlying se veral important features of reverse remodeling. These findings do not precl ude a possible primary role of neurohomonal factors underlying other facets of reverse remodeling during LVAD support.