Immunohistochemical identification of prevalent right ventricular ischemia causing right heart failure in cases of pulmonary fat embolism

Forensic significance of intracardiac expressions of Nrf2 in acute myocardial ischemia

When exposed to oxidative and electrophilic stress, a protective antioxidant response is initiated by nuclear factor erythroid 2-related factor 2 (Nrf2). However, the extent of its importance in the forensic diagnosis of acute ischemic heart diseases (AIHD), such as myocardial infarction (MI), remains uncertain. On the other hand, immunohistochemical analyses of fibronectin (FN) and the terminal complement complex (C5b-9) prove valuable in identifying myocardial ischemia that precedes necrosis during the postmortem diagnosis of sudden cardiac death (SCD). In this study, we investigated the immunohistochemical levels of Nrf2, FN, and C5b-9 in human cardiac samples to explore their forensic relevance for the identification of acute cardiac ischemia. Heart samples were obtained from 25 AIHD cases and 39 non-AIHD cases as controls. Nrf2 was localized in the nuclei of cardiomyocytes, while FN and C5b-9 were detected in the myocardial cytoplasm. The number of intranuclear Nrf2 positive signals in cardiomyocytes increased in AIHD cases compared to control cases. Additionally, the grading of positive portions of cardiac FN and C5b-9 in the myocardium was also significantly enhanced in AIHD, compared to controls. Collectively, these results indicate that the immunohistochemical investigation of Nrf2 combined with FN, and/or C5b-9 holds the potential for identifying early-stage myocardial ischemic lesions in cases of SCD.

Fat embolism after intraosseous catheters in pediatric forensic autopsies

In our center, we performed the autopsy of a child who died from drowning and presented, at autopsy, a major pulmonary fat embolism (PFE). A cardiopulmonary resuscitation (CPR) was performed, including infusion by intraosseous catheter (IIC). No other traumatic lesions and diseases classically related to a risk of PFE were detected. According to some animal studies, we considered the IIC as the only possible cause for PFE. However, we could not find literature to confirm this hypothesis in humans, especially in a pediatric population. To verify the occurrence of PFE after IIC in a pediatric population, we retrospectively selected 20 cases of pediatric deaths autopsied in our center, in which a CPR was performed, without bone fractures or other possible causes of PFE: 13 cases with IIC (group A) and 7 cases without IIC (group B). Several exclusion criteria were considered. The histology slides of the pulmonary tissue were stained by Oil Red O. PFE was classified according to the Falzi scoring system. In group A, 8 cases showed PFE: 4 cases with a score 1 of Falzi and 4 cases with a score 2 of Falzi. In group B, no case showed PFE. The difference between the two groups was statistically significant. The results of our study seem to confirm that IIC can lead to PFE in a pediatric population and show that the PFE after IIC can be important (up to score 2 of Falzi). To the best of our knowledge, our study is the first specifically focused on the occurrence of PFE after IIC in a pediatric population by using autoptic data.

Forensic significance of intracardiac heme oxygenase-1 expression in acute myocardial ischemia

Heme oxygenase-1 (HO-1), an inducible stress-response protein, exerts anti-oxidant and anti-apoptotic effects. However, its significance in forensic diagnosis of acute ischemic heart diseases (AIHD) such as myocardial infarction (MI) is still unknown. We examined the immunohistochemical expression of HO-1 in the heart samples to discuss their forensic significance to determine acute cardiac ischemia. The heart samples were obtained from 23 AIHD cases and 33 non-AIHD cases as controls. HO-1 positive signals in cardiomyocyte nuclear were detected in 78.2% of AIHD cases, however, that were detected in only 24.2% control cases with statistical difference between AIHD and non-AIHD groups. In contrast to HO-1 protein expression, there was no significant difference in the appearance of myoglobin pallor regions and leukocyte infiltration in the hearts between AIHD and non-AIHD groups. From the viewpoints of forensic pathology, intracardiac HO-1 expression would be considered a valuable marker to diagnose AIHD as the cause of death.

Approaching pulmonary fat embolism on postmortem computed tomography

PURPOSE

Pulmonary fat embolism (PFE) is a relevant diagnosis playing a role as a sign of vitality or a cause of death. Its severity is assessed according to histological grading systems like that of Falzi. The aim of this study was to determine the utility of unenhanced postmortem computed tomography (PMCT) for PFE diagnosis based on the detection of fat layers.

METHODS

Consecutive cases with PMCT and autopsy were studied retrospectively. The case group consisted of cases with positive PFE, and the control group included cases with negative PFE. Three observers independently assessed PMCT data for fat layers in the pulmonary trunk and the right and left pulmonary artery. For cases with fat layers, autopsy protocols were assessed for the cause of death, relation to trauma, and undertaken resuscitation measures.

RESULTS

Eight hundred thirty cases were included: 366 PFE positive cases (144 of Falzi grade 1, 63 of 1.5, 99 of 2, 28 of 2.5, and 32 of 3) and 464 PFE negative cases. Interrater reliabilities varied between substantial and almost perfect, and discrepancies were solved according to majority. Eighteen cases showed fat layers on PMCT (2 controls-traumatic instantaneous deaths-, 16 PFE positive cases). PMCT showed low sensitivity but high specificity for PFE diagnosis. The layers were located at the same position in the pulmonary trunk directly adjacent to the pulmonary valve distal to the right ventricle.

CONCLUSION

Fat layer on PMCT is a rare finding but relates to PFE diagnosis, especially of severe histological grade. It is to be expected in a typical position within the pulmonary trunk.

Granulomatosis with polyangiitis (Wegener's granulomatosis): a rare variant of sudden natural death

Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis, is the most common form of life-threatening small-vessel vasculitis. Although its exact pathogenesis remains unclear, GPA is believed to belong to the wide complex of autoimmune diseases due to the presence of anti-neutrophil cytoplasmatic antibodies with cytoplasmic staining pattern (c-ANCA) that is expressed in activated neutrophils. GPA predominantly manifests at the upper and lower respiratory tract and the kidneys, but the impairment of multiple organ systems is possible as well. The so-called classical clinical triad of GPA comprises sinusitis, pneumonia, and glomerulonephritis. Despite the fact that there is an elevated risk of mortality for patients suffering from GPA, sudden death due to GPA is a rare and difficult differential diagnosis of sudden natural death in forensic case work. In the present article, the rare case of a 41-year-old male, who died of a sudden death due to previously undiagnosed GPA, is demonstrated. The final diagnosis was feasible by close interdisciplinary collaboration, considering the entire body of findings obtained during autopsy, histopathological investigation, and analysis of the clinical records. Therefore, it remains necessary to point out that especially for rare causes of death, interdisciplinary collaboration is essential in order to concretize the cause of death and exclude rare differential diagnoses of sudden unexpected death of hospitalized patients in forensic case work.

Early markers of myocardial ischemia: from the experimental model to forensic pathology cases of sudden cardiac death

The goal of this study was to assess whether early markers of myocardial ischemia, identified in a previous experimental work, can be applied in forensic pathology cases of sudden, ischemic cardiac death. These markers include desphosphorylated connexin 43 (Cx43), JunB, TUNEL assay, myoglobin, and troponin T. Fourteen cases of sudden cardiac death with gross and/or histological signs of myocardial infarction and 14 cases of sudden cardiac death with signs of early ischemia at histology and positive immunoreactions for fibronectin and C5b-9 were investigated. The control group was represented by 15 hanging (global hypoxia) cases. Immunohistochemical reactions were classified into four degrees and compared among groups. Cx43 and JunB were significantly more expressed in hanging than in ischemia/infarction, but they showed a different distribution in the tissue (sub-endocardial in ischemia/infarction, diffuse in hanging) and a different intensity of the signal. TUNEL assay was significantly more expressed in the group of early ischemia than in myocardial infarction. Myoglobin and troponin T did not show any significantly different expression among the three groups. Depletion markers have a limited application in forensic cases, and this is mostly because positive (depleted) areas are difficult to distinguish from artifactually paler areas. Nuclear markers (JunB and TUNEL), on the other hand, require a well-trained eye and a high magnification in order to be distinguished. Cx43, JunB, and TUNEL assays were confirmed to be early, sensitive markers for myocardial ischemia. Nonetheless, they are not specific, as they are expressed in global hypoxia as well, but with a different tissular distribution.

Role of Survival Time and Injury Severity in Fatal Pulmonary Fat Embolism

Pulmonary fat embolism (PFE) is frequent in blunt trauma and may occasionally lead to death. A correlation between fracture grade and severity and PFE grade has been described before, but no correlation between PFE and survival time, fat crushing extent, fat crush grade, or number of body regions with fractures could be noted in this small study. To further examine this, we decided to examine the aforementioned points in a far larger study group.Autopsy protocols of 188 nonresuscitated fatalities with blunt trauma and without right heart injury, which underwent whole body dissection, were retrospectively reviewed concerning the presence and the severity of PFE, injuries, survival time, age, sex, and the body mass index.The fracture grade, the fracture severity, and the number of the fractured regions correlated very well with the grade of PFE, but the crushed regions, crush grade, and crush severity did not. We observed a time correlation between survival time and PFE only in the sense that very rapid deaths were often PFE negative. High-grade PFE was observed most often in patients having died less than 6 hours after the incident, and PFE grades of 2 or more were occasionally noted even after 48 hours.

Early markers for myocardial ischemia and sudden cardiac death

The post-mortem diagnosis of acute myocardial ischemia remains a challenge for both clinical and forensic pathologists. We performed an experimental study (ligation of left anterior descending coronary artery in rats) in order to identify early markers of myocardial ischemia, to further apply to forensic and clinical pathology in cases of sudden cardiac death. Using immunohistochemistry, Western blots, and gene expression analyses, we investigated a number of markers, selected among those which are currently used in emergency departments to diagnose myocardial infarction and those which are under investigation in basic research and autopsy pathology studies on cardiovascular diseases. The study was performed on 44 adult male Lewis rats, assigned to three experimental groups: control, sham-operated, and operated. The durations of ischemia ranged between 5 min and 24 h. The investigated markers were troponins I and T, myoglobin, fibronectin, C5b-9, connexin 43 (dephosphorylated), JunB, cytochrome c, and TUNEL staining. The earliest expressions (≤30 min) were observed for connexin 43, JunB, and cytochrome c, followed by fibronectin (≤1 h), myoglobin (≤1 h), troponins I and T (≤1 h), TUNEL (≤1 h), and C5b-9 (≤2 h). By this investigation, we identified a panel of true early markers of myocardial ischemia and delineated their temporal evolution in expression by employing new technologies for gene expression analysis, in addition to traditional and routine methods (such as histology and immunohistochemistry). Moreover, for the first time in the autopsy pathology field, we identified, by immunohistochemistry, two very early markers of myocardial ischemia: dephosphorylated connexin 43 and JunB.

Different degrees of ischaemic injury in the right and left ventricle in cases of severe, nonfatal, pulmonary embolism

Pulmonary fat embolism (PFE) is a common complication of blunt force traumas with bone fractures. Severe forms cause impedance to right ventricular (RV) ejection, with eventual right heart ischaemia and failure. In a prospective study, we have investigated 220 consecutive autopsy cases (73 females, 147 males, mean age 52.1 years, min 14 years, max 91 years). PFE was detected in 52 cases that were divided into three groups according to the degree of PFE (1-3). A fourth group of cases of violent death without PFE was used for comparison. In each case, histology (H&E, Masson) and immunohistochemistry (fibronectin and C5b-9) were performed on six cardiac samples (anterior, lateral and posterior wall of both ventricles). The degree of cardiac damage was registered in each sample and the mean degree of damage was calculated in each case at the RV and left ventricle (LV). Moreover, a parameter ∆ that is the difference between the mean damage at the RV and the LV was calculated in each case. The results were compared within each group and between the groups. In the present study, we could not detect prevalent RV damage in cases of high degree PFE as we did in our previous investigation. In the group PFE3 the difference of the degree of damage between the RV and LV was higher than the one observed in the groups PFE0-2 with the antibody anti-fibronectin. Prevalent right ventricular stress in cases of severe PFE may explain this observation.

Post-mortem cardiac 3-T magnetic resonance imaging: visualization of sudden cardiac death?

OBJECTIVES

This study aimed to investigate post-mortem magnetic resonance imaging (pmMRI) for the assessment of myocardial infarction and hypointensities on post-mortem T2-weighted images as a possible method for visualizing the myocardial origin of arrhythmic sudden cardiac death.

BACKGROUND

Sudden cardiac death has challenged clinical and forensic pathologists for decades because verification on post-mortem autopsy is not possible. pmMRI as an autopsy-supporting examination technique has been shown to visualize different stages of myocardial infarction.

METHODS

In 136 human forensic corpses, a post-mortem cardiac MR examination was carried out prior to forensic autopsy. Short-axis and horizontal long-axis images were acquired in situ on a 3-T system.

RESULTS

In 76 cases, myocardial findings could be documented and correlated to the autopsy findings. Within these 76 study cases, a total of 124 myocardial lesions were detected on pmMRI (chronic: 25; subacute: 16; acute: 30; and peracute: 53). Chronic, subacute, and acute infarction cases correlated excellently to the myocardial findings on autopsy. Peracute infarctions (age range: minutes to approximately 1 h) were not visible on macroscopic autopsy or histological examination. Peracute infarction areas detected on pmMRI could be verified in targeted histological investigations in 62.3% of cases and could be related to a matching coronary finding in 84.9%. A total of 15.1% of peracute lesions on pmMRI lacked a matching coronary finding but presented with severe myocardial hypertrophy or cocaine intoxication facilitating a cardiac death without verifiable coronary stenosis.

CONCLUSIONS

3-T pmMRI visualizes chronic, subacute, and acute myocardial infarction in situ. In peracute infarction as a possible cause of sudden cardiac death, it demonstrates affected myocardial areas not visible on autopsy. pmMRI should be considered as a feasible post-mortem investigation technique for the deceased patient if no consent for a clinical autopsy is obtained.

Severe generalised rhabdomyolysis with fatal outcome associated with isotretinoin

Isotretinoin is considered to be a safe and effective therapy in otherwise therapy-resistant acne. Elevated serum creatine phosphokinase values with or without muscle-related symptoms in isotretinoin-treated patients have been reported and interpreted as benign phenomena, lethal cases have not been described yet. We present the case of a 20-year-old male who died from severe generalised rhabdomyolysis associated with isotretinoin treatment.

Sensitivity and specificity of NT-proBNP to detect heart failure at post mortem examination

NT-proBNP, a marker of cardiac failure, has been shown to be stable in post mortem samples. The aim of this study was to assess the accuracy of NT-proBNP to detect heart failure in the forensic setting. One hundred sixty-eight consecutive autopsies were included in the study. NT-proBNP blood concentrations were measured using a chemiluminescent immunoassay kit. Cardiac failure was assessed by three independent forensic experts using macro- and microscopic findings complemented by information about the circumstances of body discovery and the known medical story. Area under the receiving operator curve was of 65.4% (CI 95%, from 57.1 to 73.7). Using a standard cut-off value of >220 pg/mL for NT-proBNP blood concentration, heart failure was detected with a sensitivity of 50.7% and a specificity of 72.6%. NT-proBNP vitreous humor values were well correlated to the ones measured in blood (r (2) = 0.658). Our results showed that NT-proBNP can corroborate the pathological findings in cases of natural death related to heart failure, thus, keeping its diagnostic properties passing from the ante mortem to the post mortem setting. Therefore, biologically inactive polypeptides like NT-proBNP seem to be stable enough to be used in forensic medicine as markers of cardiac failure, taking into account the sensitivity and specificity of the test.

Morphological identification of right ventricular failure in cases of fatal pulmonary thromboembolism

Pulmonary thromboembolism is a life-threatening event potentially determining right ventricular failure. Even if the pathophysiology of this phenomenon has been widely investigated, no morphological demonstration of right ventricular ischemic damage determining right ventricular failure in cases of fatal pulmonary embolism has been reported till now. We performed an immunohistochemical investigation with the markers fibronectin and C5b-9 in 26 cases of fatal pulmonary thromboembolism (16 ♀, 10 ♂, mean age 56.4 years), as well as in 25 cases of myocardial infarction (16♀, 9♂, mean age 60.8 years) and 20 cases of hanging (3♀, 17♂, mean age 40.8 years). In each case, at least one tissue slide from both cardiac ventricles (free wall of the right ventricle, anterior and/or posterior wall of the left ventricle) was prepared. The reactions were semiquantitatively classified and the groups compared. In the study group, the occurrence of ischemic changes at the right ventricle was significantly higher than in cases of myocardial infarction and global hypoxia due to hanging. The determining aspect of the immunohistochemical examination is the identification of the prevalent ischemic lesion at the right ventricle compared to the left one. This may indicate the primary involvement of the right ventricle thus demonstrating a right ventricular failure.

Lethal thyroid storm after uncontrolled intake of liothyronine in order to lose weight

Thyroid hormones are sometimes used for purposes for which they are not approved. Reasons for off-label use can be overweight, prevailing depressive mood, or various somatic symptoms. Information about the intake of thyroid hormones in order to lose weight can be easily obtained from inappropriate/nonmedical websites. The objective of this case report is to describe the first case of a lethal abuse of liothyronine. The case was a 29-year-old male (BMI 32) without relevant illnesses. An autopsy was performed and followed by histological, toxicological, and clinical chemistry examinations. The autopsy revealed no relevant pathology. Histology showed multiple areas of focal cell necrosis in the myocardium and signs of acute heart failure including severe edema of the lungs; the follicles of the thyroid gland were markedly plump. Postmortem laboratory results indicated lethal liothyronine intoxication. Despite prevailing opinion, uncontrolled intake of liothyronine can cause lethal thyroid storm in a euthyroid patient without manifested cardiac illnesses.