Intraventricular Placement of a Spring Expander Does Not Attenuate Cardiac Atrophy of the Healthy Heart Induced by Unloading via Heterotopic Heart Transplantation.

An important complication of the prolonged left ventricle assist device support in patients with heart failure is unloading-induced cardiac atrophy which proved resistant to various treatments. Heterotopic heart transplantation (HT_x) is the usual experimental model to study this process. We showed previously that implantation of the newly designed intraventricular spring expander can attenuate the atrophy when examined after HT_x in the failing heart (derived from animals with established heart failure). The present study aimed to examine if enhanced isovolumic loading achieved by implantation of the expander would attenuate cardiac post-HT_x atrophy also in the healthy heart. Cardiac atrophy was assessed as the ratio of the transplanted-to-native heart weight (HW) and its degree was determined on days 7, 14, 21 and 28 after HT_x. The transplantation resulted in 32±3, 46±2, 48±3 and 46±3 % HW loss when measured at the four time points; implantation of the expander had no significant effect on these decreases. We conclude that enhanced isovolumic loading achieved by intraventricular implantation of the expander does not attenuate the development of cardiac atrophy after HT_x in the healthy heart. This indicates that such an approach does not represent a useful therapeutic measure to attenuate the development of unloading-induced cardiac atrophy. [ABSTRACT FROM AUTHOR]