[Efficacy of nicorandil on myocardial protection during coronary artery bypass grafting--a comparison with diltiazem].

Diltiazem (DTZ), a calcium slow channel blocker, is estimated to be highly effective for myocardial protection and the prevention of perioperative coronary spasms (PCS). However, the use of high doses of DTZ sometimes results in difficulty in coming off cardiopulmonary bypass due to negative chronotropic activity. Nicorandil (NCD) has remarkable coronary vasodilating effect but possesses little negative chronotropic activity. The purpose of this study was to compare NCD with DTZ with respect to effect on myocardial protection during coronary artery bypass grafting (CABG). As parameters, excess lactate (delta XL), redox potential (delta Eh), left and right ventricular stroke work indices (LVSWI, RVSWI), cardiac index (C.I.), systemic vascular resistance index (SVRI.), myocardial isoenzymes (CK-MB, LDH1), number of PCS and recovery time of chronotropic action were used. delta XL, delta Eh, LVSWI, RVSWI, C.I., SVRI, CK-MB, LDH1 were measured at 0, 1, 3, 6, 9, 18 and 24 hours after the removal of aortic cross clamping. The degree of chronotropic action was evaluated by the length of the recovery time to self beat or normal sinus rhythm after the removal of aortic cross clamping. Forty patients who underwent CABG with retrograde cold blood cardioplegia between Dec. 1989 and May 1991 were divided into the NCD group (n = 20), in which 1.1 micrograms/kg/min NCD was continuously administered from the beginning of the operation and the DTZ group (n = 20), in which the initial St. Thomas cardioplegia containing 5 mg/L and subsequent cold blood cardioplegia solution contained DTZ 3.5 mg/L, for a total DTZ dose of less than 10 mg.(ABSTRACT TRUNCATED AT 250 WORDS)