A Comparative Study Of Mb, Fn And CRP On Immunohistochemical Detection For Postmortem Diagnosis Of Early Myocardial Infarction

Background:The postmortem diagnosis of EMI has been a very important and difficult problem in forensic practice.Neither to the naked eye nor with the routine histological stain H&E, early ischemic changes can be detected. Before the appearance of characteristic morphology on the routine histological stains, there have taken place a series of pathophysiologic changes in the ischemic myocardial cell. Electron microscopic, enzyme histochemical, fluorescence histochemical, biochemical methods can detect early ischemic myocardial injury. but the procedures that have been developed so far are either too elaborate to be used routinely or too questionable because they have showed much false positive or false negative. Immunohistochemical technology, as a swift, simple, convenient and practical method, show the qualitative and quantitative change of proteins in the ischemic cardiac muscle cell, which have offered a sort of possibility for postmortem diagnosis of EMI. Before this, animal studies has already verified that Mb , Fn and CRP can detected EMI. However, the changes of agonal ischemia, postmortem autolysis and other kinds of myocardiac damages , which can't be avoided in human myocardium, perhaps interfere the postmortem diagnosis of EMI. In practice, satisfactory IHC markers of high specificity and sensitivity is necessary. At present, the specificity and sensitivity of IHC markers and the campares of their practical value in the postmortem diagnosis of human EMI, are the focal point that need be studied further. Objective: In the present study, an immunohistochemical study of Mb, Fn and CRP on autopsy hearts of AMI, EMI, indirect myocardial damage, direct myocardial damage and normal myocardium is performed, that different IHC stain is showed among each trail and specificity and sensitivity of each marker are explored, in order to seek the signficant IHC markers for the postmortem diagnosis of human EMI in forensic practice. Methods: In our experiement, 48 autopsy hearts are selected which had been diagnosed in forensic practice. All the autopsy cases were divided into five groups: AMI, EMI, indirect myocardial damage, direct myocardial damage and normal myocardium. EMI were diagnosed according to the following standards: (a) The victim had a history of coronary artery disease or symptoms of death comprised chest pain, pain in the neck and left shoulder, dizziness, sweating and shock. (b) Death known to occur within 6 hours from the onset of symptoms. (c) At necropsy, severe coronary artery artherosclerosis in the anterior descending branch of left coronary artery or right coronary artery which denoted by greater than 75% obstruction of the diameter of the lumen, but none of them had macroscopic or microscopic evidence in the routine histological stain. (d) No other lethal pathological changes or explainable causes of death were found after thorough autopsy. Indirect myocardial damage group included hemorrhagic shock, pulmonary embolism and hanging cases. Direct myocardial damage group comprise of myocarditis,CO poisoning, heart contusion and electric injury cases. Normal myocardium group hold craniocerebral trauma and cerebral hemorrhage cases. Tissue blocks were selected from the region of myocardial damage. Four sections were cut and stained for Mb, Fn, CRP using IHC streptavidin/biotin/peroxidase technique. According to thecriteria of IHC stains, stain rank of each sample was performed and ratio of loss of Mb and expressive positive-ratio of Fn and CRP was determined in each group, among which statistical compares also been done. We paid a special attention to specificity, sensitivity and accuracy of immunohistochemical diagnosis for EMI in EMI, indirect myocardial damage and normal myocardium cases, all of which did't show any characteristic changes in H&E stain. At the same time, image analysis technique, as a objective method, was applied to detect and compare intensity of IHC stain in each group. Results: In AMI and direct myocardial damage, ratioes of loss of Mb were 100% and degrees of deleption also...