Monitoring of extracellular aspartate aminotransferase and troponin T by microdialysis during and after cardioplegic heart arrest

This study aims at developing per- and postopertive surveillance of the myo cardium and focuses on ischemic damage following cardioplegic heart arrest, Levels of troponin T and total aspartate aminotransferase (ASAT) were anal yzed in the myocardial interstitium of 10 patients with ischemic heart dise ase (IHD) who underwent coronary bypass surgery and in 12 patients with non ischemic heart disease (N-IHD) who underwent valvular surgery. Fluid from t he myocardial interstitium of the anterior and the lateral wall of the hear t was sampled by microdialysis probes that were implanted during surgery an d extracted percutaneously 70-100 h later. There were no adverse reactions, and the equipment did not interfere with the surgical procedures. The peak in troponin T serum levels that occurred 4 h after cardiac arrest was prec eded by a peak in troponin T levels in the microdialysates from the interst itium that occurred 1 h earlier. The concentration of troponin T in the mic rodialysate peak was 300 times higher than in the serum peak. The increase in serum ASAT levels during the first 7 h after cardiac arrest corresponded in time with a decrease in interstitial ASAT levels, which had already rea ched a maximum during cardiac arrest. The microdialysate/ serum concentrati on ratio was considerably smaller for ASAT than for troponin T. Interstitia l peak levels of troponin T correlated positively and significantly with pe ak levels of ASAT. Of the 22 patients, 15 had no postoperative events accor ding to clinical outcome, ECG and serum tests. Fourteen of these had low to normal levels of interstitial ASAT and troponin T. Conversely, atrial fibr illation and/or premature atrial contractions were recorded in 8/22 patient s, 7 of whom had elevated interstitial ASAT and/or troponin T concentration s in one or both of the sampled heart regions. The N-IHD patients had highe r levels of troponin T in the interstitium 20-70 h following cardioplegia, while the peak levels did not differ between the groups. In conclusion, mic rodialysis sampling of troponin T and ASAT is safe and allows a highly sens itive analysis of the ischemic trauma exerted by the cardioplegic arrest. C opyright (C) 2000 S. Karger AG. Basel.