A clinical comparative study between crystalloid and blood-based St Thomas' hospital cardioplegic solution

Objective: Myocardial protection with blood cardioplegia during cardiac surgery is increasingly preferred, but few studies have compared the protective effects of crystalloid cardioplegia to the same solution with blood as the only variable. This clinical study compared the protective effects of crystalloid or blood-based St. Thomas' Hospital cardioplegic solution No. 1. Methods: Fifty higher risk patients undergoing elective coronary artery bypass surgery, with an ejection fraction less than 40%, were randomly allocated to receive cold (4°C) intermittent crystalloid St. Thomas' No. 1 cardioplegia (n=25), or a similar blood-based solution (n=25) with a haematocrit of 10–12%. We determined (1) peri-operative and post-operative arrhythmias, (2) left and right ventricular function (24 h) using the thermodilution technique, (3) left ventricular high-energy phosphate content sampled before ischaemia, the end of ischaemia and the end of bypass. Results: Pre-operative haemodynamic data, aortic cross-clamp and bypass times were similar in both groups of patients; there was no mortality. At the end of ischaemia there were no differences in ATP content between groups but creatine phosphate was maintained at a significantly (P<0.007) higher level in the blood-based St. Thomas' cardioplegia group than the crystalloid St. Thomas' cardioplegia group (20±2 (SE) vs. 13±1 μmol/g dry wt, respectively). Return to spontaneous sinus rhythm was significantly (P=0.002) increased in the blood-based St. Thomas' cardioplegia group (96%) compared to the crystalloid St. Thomas' cardioplegia group (60%). Early post-operative ventricular dysfunction occurred in both groups, but normal LV function (stroke work index) recovered significantly (P=0.043) more rapidly (by 2 h) in the blood-based St. Thomas' cardioplegia group of patients. Conclusions: In a higher risk (EF<40%) group of patients undergoing elective cardiac surgery, addition of blood to an established crystalloid cardioplegic solution significantly enhanced myocardial protection by reducing arrhythmias, improving rate of recovery of function and maintaining myocardial high-energy phosphate content during ischaemia.