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 factor for early morbidity and mortality after orthotopic cardiac transplantation and is most commonly related to preexistent chronic pulmonary hypertension (CPH) in the recipient, which occurs secondary to long-standing congestive heart failure. This study was designed to assess the compensatory mechanisms of the acutely transplanted RV in the setting of recipient CPH using a canine model of bicaval cardiac transplantation (TX) and monocrotaline pyrrole (MCTP)-induced CPH.

METHODS AND RESULTS

Twenty adult mongrel dogs were used for 10 successfully completed TX experiments. Recipients received an injection of 3 mg/kg MCTP 4 months before TX. RV function was assessed with load-insensitive means (preload recruitable stroke work), and Fourier analysis was used to calculate RV hydraulic power and transpulmonary efficiency. At the time of TX, significant increases in the mean pulmonary artery pressure, mean right ventricular pressure, and pulmonary vascular resistance were observed in recipients compared with donors and were further significantly increased after cardiopulmonary bypass. Significant increases in RV preload recruitable stroke work and RV hydraulic power were observed after TX compared with before TX and occurred in association with significant decreases in transpulmonary efficiency.

CONCLUSIONS

Significant increases in pulmonary hemodynamic indexes occurred after MCTP injection 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 contractility. However, a significant decrease in transpulmonary efficiency was also observed, which may improve over time as the RV adapts to the increased afterload.