Continuous tepid blood cardioplegia can preserve coronary endothelium and ameliorate the occurrence of cardiomyocyte apoptosis.
OBJECTIVE
In modern cardiac surgery, crystalloid or blood cardioplegic solutions have been used widely for myocardial protection; however, ischemia does occur during protection with intermittent infusion of cold crystalloid or blood cardioplegic solutions. The present study was designed to evaluate the effect of different cardioplegic methods on myocardial apoptosis and coronary endothelial injury after global ischemia, cardiopulmonary bypass (CPB), and reperfusion in anesthetized open-chest dogs.


METHODS
The dogs were classified into five groups to identify the injury of myocardium and coronary endothelium: group 1, normothermic CPB without cardiac arrest; group 2, hypothermic CPB with continuous tepid blood cardioplegia, and with cardiac arrest; group 3, hypothermic CPB with intermittent cold blood cardioplegia, and with cardiac arrest; group 4, hypothermic CPB with intermittent cold crystalloid cardioplegia, and with cardiac arrest; and group 5, sham-operated control group. During CPB, cardiac arrest was achieved with different cardioplegia solutions for 60 min, followed by reperfusion for 4 h before the myocardium and coronary arteries were harvested. Coronary arteries were harvested immediately and analyzed by scanning electron microscopy. Cardiomyocytic apoptosis was detected using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling, Western blot, and DNA ladder methods.


RESULTS
Regardless of the detection method used, significantly higher percentages of apoptotic cardiomyocytes were found in group 3 and group 4 than in other groups. Expression of caspase-3 correlated with increased apoptosis. Scanning electron microscopy revealed severe endothelial injury of coronary arteries in group 3 and group 4.


CONCLUSIONS
These results point to an important explanation for the difference in cardiac recovery after hypothermic ischemia and arrest with various cardioplegic solutions.
Division of Thoracic and Cardiovascular Surgery, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan.
Chi-Hsiao
CH
Yeh
Yao-Chang
YC
Wang
Yi-Cheng
YC
Wu
Jaw-Ji
JJ
Chu
Pyng Jing
PJ
Lin
D000818:Animals; D017209:Apoptosis; D001769:Blood; D015153:Blotting, Western; D002314:Cardioplegic Solutions / Q000008:administration & dosage; D002315:Cardiopulmonary Bypass; D003331:Coronary Vessels / Q000648:ultrastructure*; D004285:Dogs; D004730:Endothelium, Vascular / Q000648:ultrastructure*; D006324:Heart Arrest, Induced / Q000379:methods; D020287:In Situ Nick-End Labeling; D008855:Microscopy, Electron, Scanning; D015428:Myocardial Reperfusion Injury / Q000473:pathology / Q000517:prevention & control; D009206:Myocardium / Q000648:ultrastructure*; D013696:Temperature
D002314:Cardioplegic Solutions