Characteristics and dynamics of post-mortem autolytic changes in myocardial structures in a hot arid zone

Rationale: Establishing the duration of death (AD) is the main issue in the process of forensic medical examinations (FME) of the corpses of persons who died from various external influences. This problem has recently attracted the attention of an increasing number of researchers in the field of forensic medicine around the world, whose efforts have been focused on finding new approaches to solving this complex problem. However, to date it has not been possible to develop methods that allow establishing AD more accurately. Aims: to identify the dynamics of autolytic changes in myocardial structures at different times after death from hanging, making it possible to establish AD. Materials and methods: The histological structure of the myocardium from 132 corpses of persons who died as a result of mechanical asphyxia by hanging was studied. Among the dead, there were 112 men, 20 women, aged from 18 to 61 years. The postmortem period ranged from 6-14 to 72-76 hours, with the largest number of deaths occurring at 6-8 hours (9.8%), 9-10 hours (9.1%), 11-12 hours (8.3 %) and 13-16 hours (7.6%). Cases with other post-mortem periods ranged from 6.8% to 3.8%. In the region of the Zeravshan Valley of Uzbekistan, which includes the main territory of the Republic, the hot season of the year usually lasts 3.6 months, from May 27 to September 14, with a maximum average daily temperature of at least + 28-32°C. The hottest month of the year in the region is July, with an average temperature maximum of +42-45°C. The cold season lasts on average 3.5 months, from November 25 to March 4, with a minimum average daily temperature below +8-11°C. Based on this observation, they were divided into the following subgroups: those who died in conditions of relatively low ambient temperatures (-7...+14°C) – 63; those who died in conditions of average temperatures (+7.0…..+20.0оС) – 46; those who died in conditions of high temperatures (not lower than +25.0….30.0оС)–23. In addition to the external temperature, other factors were taken into account: humidity, pressure, wind speed, etc., information on which was obtained through the official website of the Uzhydrometcenter (https://ru.weatherspark.com). Results: under conditions of high air temperature, autolytic changes in cardiomyocytes after death from hanging appear from 9-10 hours, by 25-28 hours an increase in the area of cell cytolysis is observed. Under conditions of average ambient temperature, similar changes in cardiomyocytes are observed after 11-12 hours, and by 25-28 hours, shrinkage of cardiomyocytes is observed; under low temperature conditions, similar conditions are observed at 13-14 and 25-28 hours. Pronounced destructive changes in vascular structures in conditions of high temperature begin from 19-20 hours of the post-mortem period, the perivascular space (PVS) greatly expands during this period, and in conditions of average temperature such states are observed by 21-22 hours, in conditions of low temperature – after 23-24 hours . Autolysis of blood cells in the vessels after death from hanging in conditions of high temperature develops after 11-12 hours of the postmortem period, and in conditions of average temperature these changes are observed after 13-14 hours, in conditions of low temperature – after 15-16 hours. Consequently, autolytic changes in the structures of blood vessels and in the intravascular contents of the myocardium develop at different times in the postmortem period, depending on the temperature conditions of the external environment. Conclusion: After death from hanging, autolytic processes in the myocardial vessels, under conditions of high ambient temperature, appear from 11-12 hours of the postmortem period; under conditions of average temperature, these changes are observed after 13-14 hours and under conditions of low temperature – after 15-16 hours of the post-mortem period. In cardiomyocytes after death from hanging, the autolytic process under high temperature conditions is observed from the 13-14 hour post-mortem period, the cytolysis process develops after 21-22 and 23-24 hours, and under conditions of average temperature, autolysis is determined at 15-16 and 17-18 hours of the post-mortem period, pronounced cytolysis is observed by 25-28 hours of the post-mortem period; in conditions of relatively low temperature, such conditions are detected after 17-18, 19-20 and 32-36 hours, respectively. As the post-mortem period increases after hanging, the area occupied by cardiomycytes and myocardial vessels significantly decrease, and the areas occupied by intermuscular edema and PVS increase, in particular: under conditions of high ambient temperature, after 6-8 hours of the postmortem period, the morphometric value of the area of cardiomyocytes is 2.81 ± 0.11, and the area vessels – 5.97±0.19, which decrease in further periods of the postmortem period. By 68-72 hours these indicators are 1.1±0.12 and 0.06±0.19, respectively (P≤0.001); under conditions of average temperature, after 6-8 hours of the postmortem period, the morphometric value of the cardiomyocyte area is 2.87 ± 0.11, and the vascular area is 6.01 ± 0.19. By 68-72 hours, the area of cardiomycytes is 1.5±0.13, and the area of vessels is 1.16±0.19 (P≤0.001); under low temperature conditions, after 6-8 hours of the postmortem period, the morphometric value of the area of cardiomyocytes is 2 .93±0.11, and the area of the vessels is 6.03±0.19. By 68-72 hours these indicators are 1.68±0.14 and 1.6±0.19, respectively (P≤0.001).