Bedeutung und Problematik enzymatischer Gewebs- und Serumbefunde beim frischen Myokardinfarkt

[Comparative enzyme-histochemical studies on normal myocardium, in cases of coronary insufficiency and myocardial infarction (author's transl)]

Comparative histochemical studies with Tetrazolium salt solutions were performed on 25 human and 3 canine hearts. After perfusion of whole hearts with Tetrazolium solutions extensive unstained areas were observed which proved to be artefacts, since they reacted positively after incubation of the heart-slices. The perfusion method of Lichtig, Feldman, Glagov and Wissler (1973) which was proposed for macroscopic and microscopic diagnosis of ischemic cardiac lesions was not found to be suitable for the identification of microcirculatory disturbances. The usual incubation method, however, proved to be useful for the macroscopic localization of recent myocardial infarcts.

Effects of myocardial revascularization following acute coronary occlusion in pigs

In a comparative study in pigs the extent of myocardial infarction has been estimated following a temporary three hour coronary occlusion and following a permanent coronary ligation. For evaluation of the cellular injury the infarct size has been determined by a histochemical staining procedure and correlated with serum enzyme studies (creatine phosphokinase, alpha-hydroxybutyric dehydrogenase) in the surviving animal. No significant difference could be detected between the two experimental groups and the extent of cellular damage was similar. A strict linear correlation was found between the serum enzyme activity plotted logarithmically and the morphological infarct size. Likewise the incidence of ventricular fibrillation depended on the extent of cellular injury. Myocardial revascularization does not appear to benefit a pig heart subjected to an acute coronary occlusion lasting three hours or more. Revascularization may even be harmful by creating a haemorrhagic infarct, as found in all the animals submitted to a transient coronary occlusion.

Macroscopic identification of early myocardial infarction by dehydrogenase alterations

A method utilizing a general dehydrogenase reaction has been used to demonstrate early gross myocardial infarctions. The procedure takes advantage of substrate and enzyme loss from the damaged myocardium. In the viable muscle, where endogenous substrates, coenzymes, and dehydrogenases are present, reduction of Nitro-BT yields a dark blue formazan. Necrotic muscle fibres remain unstained by this technique.A survey of 31 human hearts obtained at necropsy disclosed that there is no alteration in the Nitro-BT reaction following acute coronary insufficiency with sudden death or severe congestive heart failure. The earliest myocardial infarct to show loss of dehydrogenase activity was of eight hours' duration. Post-infarction scars and patchy interstitial fibrosis provided very precise information concerning topographic relationships when this method was applied to heart slices.