Nature of pulmonary hypertension in congestive heart failure. Effects of cardiac transplantation.

Pulmonary hypertension associated with congestive heart failure carries a risk of right ventricular failure after cardiac transplantation. Few data, however, are available on the hemodynamic behavior of the pulmonary circulation in these patients. We therefore studied mean pulmonary artery pressure minus left atrial pressure (estimated by pulmonary artery occluded pressure) versus cardiac output relationships in 20 patients with congestive heart failure evaluated for orthotopic cardiac transplantation, and we repeated this study either within the first 3 days postoperatively (n = 10) or 1 month postoperatively (n = 11). Cardiac output was increased by physical exercise or (in the early postoperative period) by an infusion of dobutamine. Reversibility of pulmonary hypertension was tested by an infusion of prostaglandin E1. At preoperative evaluation, the extrapolated pressure intercept of pulmonary vascular pressure:flow plots was negative in 10 of the patients, suggesting active exercise-induced pulmonary vasoconstriction. In the other 10 patients, the extrapolated pressure intercept was positive, suggesting that an increased closing pressure contributed to pulmonary hypertension. However, transplantation was constantly associated with proportional decreases of pulmonary artery pressure and left atrial pressure. On the other hand, pulmonary vascular pressure:flow plots were displaced to equal or lower pressures and to higher flows by prostaglandin E1 before as well as after transplantation. We conclude that in patients with congestive heart failure evaluated for cardiac transplantation, an increased pulmonary venous pressure more than a reversible increase in closing pressure determines the severity of pulmonary hypertension.