The Experimental Study Of Heart-type Fatty Acid Binding-protein In Diagnosis Of Early Myocardial Ischemia

Objective: The changes of heart-type fatty acid binding protein (H-FABP) in rats' myocardial cells and plasma were observed at different intervals after acute myocardial ischemia, and the sensitivity of H-FABP in the postmortem diagnosis of myocardial ischemia was studied on human hearts to find an objective and sensitive method for the forensic pathologists to diagnose sudden death dying from early myocardial ischemia (EMI).Methods: 1, The rat model of acute myocardial ischemia was induced by ligating the anterior branch of the left coronary artery following the method of Selye. 54 Wistar rats, weighting 250-350g of either sex, were randomly distributed into three control groups and six study groups. The left coronary artery of rats in the six study groups was ligated for 15min, 30min, Ih, 2h, 4h, 8h respectively and then killed. The contents of H-FABP and Mb in myocardial cell were detected with immunohistochemisty staining and the concentration of H-FABP in plasma was measured with enzyme-linked immuno-sorbent assay (ELISA). 2, 22 cases autopsy human hearts, in which 14 cases for male and 9 cases for female, aging from 18 to 69, were selected from the archives of forensic department of Wuhan University. They were distributed into there groups: (1) Positive control group or definite myocardial infarction group; 7 cases, with macroscopic or microscopic evidence of myocardial infarction with hematoxylin-eosin (HE) staining. (2) Negative control group or non-cardiac death group; 6 cases, all died from craniocerebral injury with no cardiac abnormality. (3) Study group or suspected myocardial ischemia group; 9 cases, with severe to moderate coronary atherosclerosis at autopsy, but none of them had macroscopic or microscopic (HE staining) evidence of myocardial infarction. No other explainable causes of death were found through systemic examination. The changes of H-FABP staining in normal, infarcted and suspected ischemia of myocardial cells were studied with immunohistochemistry staining on human hearts to verify the results of animal experiments.Results: 1 , animal model:(l) Of the result with immunohistochemistry staining: There was no significant difference among three control groups for H-FABP staining. As for Mb, the nuance between A3 group and Al or A2 group could be found. It was observed that there were both H-FABP and Mb depletion in ischemic myocytes in 15min myocardial ischemia group. Along with the ischemia time, the wavy-like advance of depleting H-FABP and Mb, both in size and intensity, from subcardium to subepicardium could be found. There was obvious significant difference between ischemia groups and control groups for H-FABP and Mb. The depletion area of H-FABP was different from that of Mb only in the 4h myocardial ischemia group. (2) Of the result with ELISA: The concentration of H-FABP in the plasma rised markedly early from the 15min myocardial ischemia group and reached the peak in the 4h myocardial ischemia group, then descended gradually. The plasmic concentration of H-FABP appeared significant difference between the myocardial ischemia groups and the control groups. 2, Human hearts: In all 7 cases of positive control group with definite infarcted area, significant or total loss of both H-FABP and Mb in most cardiomyocytes mixed with some decreased immune-staining cardiomyocytes and normal cells. In negative control group, strong cytoplasmic H-FABP and Mb immuno-reactivity exhibited in the cardiac myocytes, although staining of some cells were light. Three cases in study group showed extensive loss of staining for H-FABP, three cases exhibited focal loss and three cases sparsely loss. The loss of staining for Mb is quite similar to that of H-FABP in the suspected myocardial ischemia group.Conclusion: The regularity-changes of H-FABP in rats' myocardial cells and in the plasma have been observed at different intervals after acute myocardial ischemia and its high sensitivity for the diagnosis of early myocardial ischemia probably makes H-FABP a sensitive marker in diagnosis of the sudde...