Effects of myocardial preservation on enzyme levels in serum and myocardium: a clinical study comparing cold crystalloid versus warm blood cardioplegia.
BACKGROUND
Enzyme activities have been recognized as one of the parameters in the assessment of the effects of various forms of myocardial preservation. However, comparisons between different methods of myocardial protection by the use of enzyme assay in clinical settings in uncommon.


METHODS
Twenty patients who underwent open-heart valve replacement were divided equally into two groups: intermittent perfusion of cold crystalloid (St. Thomas Hospital solution) with hypothermic cardiopulmonary bypass (CPB) (Group I) and continuous administration of warm blood cardioplegia with normothermic CPB (Group II). The groups were similar with respect to sex, age, body surface area and preoperative ventricular function. Blood samples were obtained from an indwelling radial arterial catheter or from the arterial end of the oxygenator. Biopsy specimens from the right atrium were obtained immediately before aortic declamping (ischemic period), and 30 minutes after crossclamp removal (reperfusion period). The cumulative release of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and its isoenzymes; linear correlation between (iso)-enzymes of each group and multivariate regression between blood potassium and serum enzymes were determined. The enzyme levels of myocardial specimens including ALT, AST, LDH, creatine phosphokinase (CK), superoxide dismutase (SOD), and malondialdehyde (MDA) were recorded and compared both between the two groups and within each group.


RESULTS
No significant intergroup difference was found in the cumulative release of the serum (iso)-enzymes. Close relationships were found in all the correlation coefficients except for the CK-ALT couple in Group I. Neither were intergroup differences found in each parameter of the linear correlations between the (iso)-enzymes. A close correlation between blood potassium and serum enzymes was found in Group I rather than in Group II. Differences of enzyme levels of myocardial specimens between ischemic periods and reperfusion periods were also not statistically significant either within the group or between the groups.


CONCLUSIONS
Judging from the results of enzyme assay, similar myocardial preservation effects against ischemia-reperfusion injuries could be obtained by either of the techniques of myocardial preservation.
Yuan
S M
SM
Department of Cardiovascular Surgery, Great Wall Hospital, Beijing, P.R.C.
D000410:Alanine Transaminase / Q000032:analysis; D001219:Aspartate Aminotransferases / Q000032:analysis; D003402:Creatine Kinase / Q000032:analysis; D006324:Heart Arrest, Induced; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D009206:Myocardium / Q000201:enzymology*; D009926:Organ Preservation
D007770:L-Lactate Dehydrogenase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D003402:Creatine Kinase