Diagnosis of Early Myocardial Infarction by Histochemical Staining of Heart on Autopsy

Abstract

INTRODUCTION : The incidence of Sudden Unexpected Death is increasing globally. Cardio vascular disease is the most common cause for sudden death. Eighty percent of sudden cardiac death is due to coronary arterial disease36. In 25% of cases death occurs abruptly and unexpectedly within first hour of onset of clinical symptom. Most often, the identification of early change of Myocardial infarction becomes difficult during postmortem examination, as gross change of infarct will not be apparent for 24 to 48 hrs following myocardial ischemic damage Histochemical staining techniques using azo dyes are based on the fact that ischemic myocardial cells lose their membrane integrity and release their enzyme contents in to the blood, resulting in a marked decrease or total depletion of these enzymes in the ischemic areas of the myocardium. Enzyme depleted infarct myocardium remain unstained, which is the principle of this study. AIMS AND OBJECTIVES : 1. To diagnose early Myocardial Infarction by Histochemical staining of Myocardium using Triphenyl Tetrazolium Chloride (TTC) while performing autopsy, in the absence of appreciable macroscopic changes in the myocardial tissue. 2. To confirm those identified areas of early myocardial infarction by Histopathological Examination. 3. To determine the diagnostic validity of the Histochemical Staining (TTC) of heart in gross detection of early Myocardial Infarction. MATERIALS AND METHODS: Slices from 18 hearts of suggested or suspected sudden cardiac death were incubated in 1% Triphenyl Tetrazolium Chloride Solution for 20 min. after adjusting the pH of the solution using phosphate buffer. The heart slices were examined for unstained area. Normal myocardium was stained whereas infarct areas remain unstained. Both stained and unstained areas were subjected to Histopathological examination for early Myocardial Infarction. OBSERVATION AND RESULTS: Of 18 hearts stained with TTC solution, 11 hearts showed positive TTC result, 5 hearts showed negative result, 1 heart showed false positive result and 1 heart showed false negative result. CONCLUSION : Histochemical staining using 1% TTC solution is a reliable method in detection of early myocardial infarction. Though this method has diagnostic validity of 88.88%, it could not identify death due to arrhythmias.