Significance of hot shot in patients with unstable angina undergoing emergency coronary artery bypass graft surgery

Abstract

We investigated the efficacy of terminal warm blood cardioplegia (hot shot) in patients with cardioplegic techniques. From January 1991 through April 1993, 68 patients recieved hypothermic cardioplegia induced by cold modified St. Thomas' Hospital solution containing 10mg/L of diltiazem hydrochloride followed by intermittent infusion of the cold crystalloid solution or cold blood cardioplegia without hot shot. From May 1993 through December 1994, 65 patients recieved hot shot before removal of aortic cross-clamp following the hypothermic cardioplegia. The earlier group consisted of 51 patients with stable angina undergoing elective CABG and 17 patients with unstable angina undergoing emergency of urgent CABG. The later group consisted of 44 patients with stable angina and 21 patients with unstable angina. The unstable angina undergoing coronary artery bypass graft surgery (CABG) using antegrade incidence of perioperative myocardial infarction was significantly higher in patients with unstable angina without hot shot (35%) compared to those with stable angina with and without hot shot (2% and 4%, respectively) and those with unstable angina with hot shot (5%). The level of maximum creatine kinase-MB (IU/L) was significantly greater in patients with unstable angina without hot shot (134 +/- 26) compared to those with stable angina with and without hot shot (57 +/- 7 and 65 +/- 4, respectively) and those with unstable angina with hot shot (57 +/- 8). The doses of dopamine and dobutamine (mg/kg) administered during 48 hours after CABG was not different between patients with stable angina with and without hot shot (13.9 +/- 0.9 vs 13.9 +/- 0.9), but tended to be lower in patients with unstable angina with hot shot (13.7 +/- 1.3) compared to those without hot shot (18.6 +/- 2.1). Left ventricular stroke work index (g.m/m2/b) immediately after CABG was comparable between patients with stable angina with and without hot shot (40 +/- 2.0 vs 36 +/- 1.5), but significantly greater in patients with unstable angina with hot shot (39 +/- 2.3) compared to those without hot shot (29 +/- 2.2). These results suggest that hot shot may provide a significant benefit in myocardial preservation during CABG especially in patients with unstable angina.