Whole hearts from 16 patients with end-stage congestive heart failure (CHF) at the time of cardiac transplantation without LVAD support, 16 patients with LVAD support, and 3 patients with BiVAD support were used to study RV EDPVRs, with estimation of chamber stiffness. Perfused isolated myocardial trabeculae were used for functional studies. Furthermore, RV free wall samples were used for histology and collagen determination by hydroxyproline.
The RV size, calculated from the ex vivo RV EDPVRs, RV mass, and myocyte diameter were significantly smaller in BiVAD-supported hearts than in non-supported or LVAD-supported hearts (p < 0.05) and reached normal levels. Furthermore, cardiomyocyte function demonstrated a normalized response to increased stimulation frequency and after perfusion with isoproterenol following BiVAD support. In addition, myocardial collagen content and chamber stiffness increased tremendously after BiVAD support (p < 0.05 vs CHF and LVAD).
BiVAD-induced hemodynamic unloading support resulted in significant reverse structural and functional remodeling of the right chamber. The lack of these findings during LVAD support alone provides additional support that diastolic pressure and volume unloading is an important mechanism underlying the process of reverse remodeling.