Summary
Twenty-three patients underwent cardiac surgery, for valve replacement, valve reconstruction, aorto-coronary bypass grafting, aneurysmectomy or combinations of these. Excised cardiac tissue was obtained from left ventricular (LV) papillary muscle (17 patients), LV outflow tract (3 patients), or LV aneurysms (3 patients). A total of 34 myocardial samples, collected from excised cardiac tissue, were analysed for creatine kinase (CK), CK-isoenzymes, cytoplasmic and mitochondrial isoenzymes of aspartate aminotransferase (cAST and mAST, respecttvely), and lactate dehydrogenase (LDH) isoenzymes.
Myocardial CK activity correlated positively with preoperative LV ejection fraction (p < 0.001), negatively with the preoperatively measured extent of LV wall motion abnormalities (p < 0.001), and negatively with preoperative LVEDP (p < 0.02). Myocardial CK activity was negatively correlated with preoperative validity class (p < 0.005). However, no correlation existed between myocardial CK activity and postoperative validity.
Excluding the biopsies from LV aneurysms, myocardial CK activity was positively correlated with the fraction H-subunits in LDH (p = 0.02), and was negatively correlated with the fraction mAST in total AST (p < 0.005). While cAST activity was proportional to CK activity in the biopsies from VL papillary muscle and LV outflow tract, mAST activity declined only with 2.4 ± 1.2 % per 10% fall of CK.
The increase of mAST/cAST ratio with decreasing CK, together with the decrease of LDH-H/LDH and CK-M/CK ratios with decreasing CK, indicated the presence of an adaptation process in a myocardium with low CK activity rather than a process of necrosis. This was illustrated by the finding that biopsies (n = 6) from LV aneurysms revealed normal ratios of mAST/AST (0.61), CK-M/CK (0.86) and LDH-H/LDH (0.83), indicating that necrosis and eventually fibrosis, are associated with depressed myocardial activities of both cytoplasmic and mitochondrial enzymes, the percentual decreases of which are identical.
Key words
Myocardial biopsies - Myocardial enzymes - Heart valve replacement - Ventricular aneurysms - Cardiac function
