Better preserved pulmonary endothelium-dependent vasodilation with off-pump coronary surgery

Objective - To investigate if endothelium-dependent vasodilation in the pul monary circulation was better maintained after off-pump coronary artery byp ass grafting, (CABG). An impaired pulmonary vascular response to acetylchol ine has been observed after cardiopulmonary bypass (CPB) in children, adult s and experimentally. Design - Fourteen patients operated off-pump were compared with 21 patients undergoing conventional CABG with CPB. The indexed pulmonary vascular resi stance was measured before and durino, an infusion of acetylcholine, aiming at a concentration of 10(-6) Mol/l in the pulmonary artery. Twelve patient s operated on-pump received saline instead of acetylcholine. Results - Before surgery pulmonary vascular resistance decreased during inf usion of acetylcholine by 28% and 25% in the off-pump and on-pump groups. A fter surgery the decrease was 16% and 6%, respectively (p = 0.028 and p < 0 .001, compared to preoperative response). The response did not differ betwe en the two groups before, but did so after surgery (p = 0.01). Saline had n o effect. Conclusion - The better maintained endothelium-dependent vasodilation in th e off-pump group indicated less endothelial dysfunction.