Myocardial damage; frequency of patients undergoing CABG receiving intermittent antegrade warm blood cardioplegia at extended interval

ABSTRACT

Intermittent antegrade warm blood cardioplegia is routinely used as a mean of myocardial protection since its introduction. There is a considerable debate on the longest time off cardioplegia interval during aortic cross clamping. To see the frequency and extent of myocardial damage in patients undergoing CABG receiving intermittent antegrade warm blood Cardioplegia at LTOC [longest time off cardioplegia] 11-15 minutes [Group I] and 16-20 minutes [Group II]. A randomized prospective study involving 94 patients was arranged to see the safe periods of intermittency. There were two groups of patients having LTOC of 11-15 minutes [Group I] and 16-20 minutes [Group II]. 20 minutes was the upper limit. The duration of study was from 1-09-2013 to 10-02-2014. Data was analyzed using SPSS Version 16. Independent sample t-test and chi-square were applied to see the significance. Mean age was 54.1 +/- 9.36 years. There were more males as compared to females. More than 50% of the patients had Hypertension and Diabetes. There was no urgent surgery. Triple vessel disease [TVD] was present in 48.9% patients and 40.4% had Double vessel disease [DVD]. Average blood flow during CPB was 2.4 +/- 0.14 [L/ min.m-2]. Average body temperatures were 31.7 +/- 2.30 C. Cardioplegia temperature was 36-370 C. According to Left Ventricular Function Classification, 43.6% of the patients were of LV grade II and 10.6% of LV grade III. There was no significant increase in the levels of CK-MB in two groups. 77.8% patient in Group I and 66.7% in Group II gained spontaneous rhythm [p-value 0.16]. IABP was inserted in 5.4% patients in group I and 5.6% in group II [p-value 0.97]. There was no failure to wean off from bypass and no peri-operative mortality. The levels of inotropes viz dopamine and epinephrine on weaning were also almost the same. Perioperative MI occurred only in 7 patients [ruled out by biochemical evidence]. A reasonable margin of safety exists with intermittent antegrade warm blood cardioplegia in these two groups. So the LTOC [longest time off cardioplegia] up to 20 minutes is unlikely to lead to adverse clinical outcomes and is clinically acceptable