Endothelin during cardiovascular surgery: the effect of diltiazem and nitroglycerin

To investigate whether the vasoconstrictor peptide endothelin (ET) is elevated during cardiovascular surgery and might predispose to perioperative vasoconstriction and ischemia, we compared the effect of the calcium channel blocker diltiazem with that of the nitric oxide (NO) donor nitroglycerin on ET and hemodynamics in 32 patients undergoing coronary artery bypass grafting (CABG). Following a double-blind protocol, 16 patients (3 women, 13 men; ages 63 +/- 10 years) received 1 microgram/kg/min nitroglycerin and 16 patients (5 women, 11 men; ages 64 +/- 8 years) received 3 micrograms/kg/min diltiazem intravenously 30 min before until 12 h after CABG. ET was measured in the superior vena cava before, during, and 1 h after CABG. Compared with ET levels before CABG, ET was significantly elevated during CABG and further increased after CABG (p < 0.05). During and after surgery, ET levels were lower in patients receiving diltiazem than in those receiving nitroglycerin (both p < 0.01). Mean arterial blood pressure and heart rate were lower in patients receiving diltiazem compared with those receiving nitroglycerin (both p < 0.05). These data demonstrate that diltiazem is more effective than nitroglycerin in preventing ET increase during cardiovascular surgery. Studies using ET receptor antagonists may be useful in assessing the clinical relevance of ET levels with respect to the risk for perioperative vasoconstriction and ischemia.