Detecting heart tissue injury in electrocution human cases using heart-type fatty acid-binding protein 3

Introduction: In the medicolegal daily practice, electrocution is a traumatic cause of death owing to wide use of electricity and electrical devices in different activities of modern life at home and workplaces. Electrical current passage through tissues elaborates different types of energy (the electrical, thermal, and mechanical energies) which can cause skin lesions, multiorgan damage, and even death. The severity and extent of tissue injuries depend on the current type (alternating current [AC] or direct current), its strength (amperage), voltage (low or high), frequency, tissue resistance, duration of exposure, and its pathway through the body. Microscopic examination of tissue samples from the heart may show nonspecific findings to electrocution, but sometimes none is detected by conventional hematoxylin and eosin stains (H and E). Therefore, immunohistochemical studies could help the forensic pathologists in their diagnosis, especially cases with less typical findings or obscure circumstances. Heart-type fatty acid-binding protein 3 (H-FABP3) is a small cytoplasmic protein of (15 kDa), composes of 133 amino acids, involves in active fatty acid metabolism, and transports fatty acids from the cell membrane to mitochondria for oxidation. Due to its cytoplasmic location and small molecular weight, it released from cardiac myocytes into the circulation following an ischemic episode. Objective: This study was conducted to evaluate the effect of electric current on the expression of H-FABP3 in human heart tissue autopsy samples. Methods: Human heart tissue samples were collected during the period from January 1 2016 to June 30, 2016, through autopsy of 30 medicolegal cases of electrocution as well as 30 cases of fatal head injuries which were used as control. They were examined by conventional histopathological H and E stain and immunohistochemical technique so that H-FABP3 was detected using FABP3 polyclonal antibody and demonstrated by ready to use biotin-free, one-step horseradish peroxidase polymer anti-mouse, rat, and rabbit immunoglobulin G with 3,3'-diaminobenzidine to achieve the aim of this study. Results: This study shows that electric shock was the fifth cause of traumatic death, being responsible for death of only 4.5% of cases referred to the medicolegal directorate in Baghdad during the period of study. It is almost accidental death in Iraqi society with higher incidence to be due to contact with low-voltage household AC sources with young males at the age of (15–20 years old) are being more vulnerable to fatal electrical injury than females during their early productive life (with male:female ratio = 6:1). Heart tissue ischemia is a major cause of death following electrocution, especially when victim being in contact with household low-voltage AC in the presence of transthoracic pathway to the ground and low body resistance due to skin wet which can cause death within a minute in association with mild if any electrical skin burns. Electrocution has a significant effect on H-FABP3 stain total index as it causes depletion of FABP3 total stain index with mean of 0.28 ± 0.149177SD for tissue sections of the heart muscle in the affected areas of human cases. Conclusions: Immunohistochemical heart tissue samples' examination which shows dramatic depletion in H-FABP3 total stain index in affected area(s) is of value in detecting heart tissue injury caused by electrocution during the early period after death even in the absence of grossly and microscopically visible lesion(s).