RIGHT-VENTRICULAR ADAPTATION TO INCREASED AFTERLOAD AFTER ORTHOTOPIC CARDIAC TRANSPLANTATION IN THE SETTING OF RECIPIENT CHRONIC PULMONARY-HYPERTENSION

Background Right ventricular (RV) failure remains an important risk fa ctor for early morbidity and mortality after orthotopic cardiac transp lantation and is most commonly related to preexistent chronic pulmonar y hypertension (CPH) in the recipient, which occurs secondary to long- standing congestive heart failure. This study was designed to assess t he compensatory mechanisms of the acutely transplanted RV in the setti ng of recipient CPH using a canine model of bicaval cardiac transplant ation (TX) and monocrotaline pyrrole (MCTP)-induced CPH.Methods and Re sults Twenty adult mongrel dogs were used for 10 successfully complete d TX experiments. Recipients received an injection of 3 mg/kg MCTP 4 m onths before TX. RV function was assessed with load-insensitive means (preload recruitable stroke work), and Fourier analysis was used to ca lculate RV hydraulic power and transpulmonary efficiency. At the time of TX, significant increases in the mean pulmonary artery pressure, me an right ventricular pressure, and pulmonary vascular resistance were observed in recipients compared with donors and were further significa ntly increased after cardiopulmonary bypass. Significant increases in RV preload recruitable stroke work and RV hydraulic power were observe d after TX compared with before TX and occurred in association with si gnificant decreases in transpulmonary efficiency. Conclusions Signific ant increases in pulmonary hemodynamic indexes occurred after MCTP inj ection and were further significantly increased after cardiopulmonary bypass. In the setting of recipient CPH, RV performance adapts acutely after bicaval TX with significant increases in power and contractilit y. However, a significant decrease in transpulmonary efficiency was al so observed, which may improve over time as the RV adapts to the incre ased afterload.