The use of tolazoline hydrochloride as a pulmonary vasodilator in potentially fatal episodes of pulmonary vasoconstriction after cardiac surgery in children.

Infants and children with highly reactive pulmonary vasculature may die of an acutely increased pulmonary vascular resistance (PVR) during or after correction of congenital heart defects. Fifteen patients, 11 infants ages 2--12 months (mean 5.3 months) and 4 children ages 2--10 years (mean 5.8 years), were treated with tolazoline to reduce an acutely elevated PVR during or after operation. Five patients had total anomalous pulmonary venous drainage, six had ventricular septal defect and four had truncus arteriosus. Preoperatively, the ratio of systolic pulmonary artery pressure to systemic artery pressure (PAP/SAP) was 0.57--1.54 (mean 0.93), and PVR was 1.8--20 units/m2 (mean 6.2 units/m2). The pulmonary artery pressure was monitored postoperatively by pulmonary artery lines placed at surgery (12 patients) or by balloon flotation catheters (two patients). Acute elevations in PAP/SAP accompanied by clinical deterioration occurred during attempted withdrawal from cardiopulmonary bypass in three patients, during apparently optimal ventilation postoperatively in eight patients, and after withdrawal of ventilatory support in four patients. Administration of tolazoline as a bolus (1--2 mg/kg) followed by infusion of 1--2 mg/kg/hour resulted in a rapid and sustained decrease in PAP/SAP, from 1.00 +/- 0.18 (mean +/- SD) to 0.40 +/- 0.09 (p less than 0.001), and was effective management for all these clinical crises. The use of tolazoline may prevent a fatal outcome from acute elevation of PVR in the perioperative period.