Objective: To investigate if endothelium-dependent vasodilation in the pulmonary circulation was better maintained after off-pump coronary artery bypass grafting (CABG). An impaired pulmonary vascular response to acetylcholine has been observed after cardiopulmonary bypass (CPB) in children, adults and experimentally.
Design: Fourteen patients operated off-pump were compared with 21 patients undergoing conventional CABG with CPB. The indexed pulmonary vascular resistance was measured before and during an infusion of acetylcholine, aiming at a concentration of 10(-6) mol/l in the pulmonary artery. Twelve patients operated on-pump received saline instead of acetylcholine.
Results: Before surgery pulmonary vascular resistance decreased during infusion of acetylcholine by 28% and 25% in the off-pump and on-pump groups. After surgery the decrease was 16% and 6%, respectively (p = 0.028 and p < 0.001, compared to preoperative response). The response did not differ between the two groups before, but did so after surgery (p = 0.01). Saline had no effect.
Conclusion: The better maintained endothelium-dependent vasodilation in the off-pump group indicated less endothelial dysfunction.