THE USEFULNESS OF THE LACTATE-DEHYDROGENASE MACROREACTION IN AUTOPSY PRACTICE

The detection of recent myocardial damage by means of the macroscopic lactate dehydrogenase reaction (LDHr) linked to nicotinamide adenine d inucleotide diaphorase (NADHd), conducted in a liquid medium is greatl y insensitive to postmortal autolysis. In 10 heart cones (i,e., cardia c ventricles severed underneath the coronary sulcus) stored at 6 degre es C for up to 114 h after death, no autolytic artifacts appeared on f reshly cut apical surfaces of transverse myocardial slices. In 10 cone s kept at room temperature for up to 95 h after death, no artifacts ap peared in eight cases; in two cases the LDHr was impaired by postmorta l bacterial spread and decomposition of the myocardium. Intravital per fusion of injured myocardium increases the sensitivity of the LDHr. Po stmortal standstill of circulation is decisive in preserving dehydroge nase activities in undamaged myocardium. An artificial decrease in enz yme activity always appeared on the nonrecent, basally facing cut surf aces of slices exposed to air and fluid oozing out of the myocardium f or long periods, even if the exposed surface of the cone was kept at 6 degrees C and wrapped in plastic. In normal practice, when bodies are stored in a refrigerating unit, the LDHr may still indicate myocardia l damage more than 114 h after death.