ADENOSINE EFFECTIVELY CONTROLS PULMONARY-HYPERTENSION AFTER CARDIAC OPERATIONS

Background. Pulmonary hypertension secondary to increased pulmonary va scular resistance may greatly complicate the perioperative management of patients having cardiac operations. Adenosine may have a therapeuti c role as a selective pulmonary vasodilator. The purpose of this study was to examine the pulmonary hemodynamic effects of a central venous infusion of adenosine in cardiac operative patients with pulmonary hyp ertension. Methods. Ten cardiac patients with pulmonary hypertension ( age, 62 +/- 6 years) were studied in the operating room under general anesthesia after weaning from cardiopulmonary bypass. Cardiac output, pulmonary vascular resistance, systemic vascular resistance, mean pulm onary arterial pressure, and mean systemic arterial pressure were dete rmined before, during, and after central venous infusion of adenosine (50 mu g . kg(-1). min(-1)) for 15 minutes. Statistical analysis was b y analysis of variance, and significance was accepted at p < 0.05. Res ults. Adenosine produced significant pulmonary vasodilation. Mean pulm onary arterial pressure was lowered from 36 +/- 1 to 28 +/- 2 mm Hg (p < 0.05), and pulmonary vascular resistance was lowered from 560 +/- 3 0 to 260 +/- 30 dynes . s . cm(-5) (p < 0.05) during adenosine adminis tration. At the same time, cardiac output rose from 4.0 +/- 0.6 to 6.2 L/min (p < 0.05). Pulmonary vascular resistance, mean pulmonary arter ial pressure, and cardiac output returned to baseline after the adenos ine infusion was stopped. There was no change in systemic mean arteria l pressure during adenosine infusion. Conclusions. Adenosine may be us ed clinically as a selective pulmonary vasodilating agent to optimize pulmonary hemodynamic indices without adverse systemic hemodynamic eff ects in patients with pulmonary hypertension having cardiac operations . It may be particularly valuable in patients with right heart dysfunc tion by selectively lowering right ventricular afterload.