Evaluation of cardiac troponin I immunoreaction in autopsy hearts: a possible marker of early myocardial infarction

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.

Dystrophin and metalloproteinase 9 in myocardial ischemia: A post-mortem immunohistochemical study

The presented study evaluated the expression of dystrophin and MMP-9 in cases of sudden cardiac death (SCD) due to coronary atherosclerotic disease (CAD) in order to analyze the characteristics and the chronology of their expression, providing evidence on the possible role in post-mortem diagnosis of myocardial ischemia. The expression of these proteins was also compared to C5b-9 complex and fibronectin expression to evaluate any differences. Two groups of CAD-related SCD, respectively group 1 with gross and/or histological evidence and group 2 with no specific histological signs of myocardial ischemia, were used. A third group formed by cases of acute mechanical asphyxiation was used as a control. The immunohistochemical staining by dystrophin, MMP-9, C5b-9, and fibronectin antibodies was performed. The study revealed that dystrophin and MMP-9 showed different expression in group 1 and group 2 as, respectively, different degree of sarcolemmal staining depletion and increasing of interstitial and granulocytes immunopositivity. Moreover, loss of dystrophin staining and C5b-9 immunopositivity were more significant when compared to MMP-9 increasing. Dystrophin and MMP-9 seemed to be useful immunohistochemical markers for the detection of myocardial ischemic damage. However, the comparison of the four markers suggested that loss of dystrophin could be considered as an earlier marker.

Immunohistochemistry in the Detection of Early Myocardial Infarction: Systematic Review and Analysis of Limitations Because of Autolysis and Putrefaction

The postmortem diagnosis of acute myocardial infarction is one of the main problems in forensic practice, especially in cases in which death occurs soon after (from minutes to a few hours) the onset of the ischemic damage. Several authors have highlighted the possibility to overcome the limits of conventional histology in this diagnosis by utilizing immunohistochemistry. In the present research, we examined over 30 scientific studies and picked out over 20 main immunohistochemical antigens analyzed with a view to enabling the rapid diagnosis of early myocardial infarction. The aim of our review was to examine and summarize all the principal markers studied to date and also to consider their limitations, including protein alteration because of cadaveric autolysis and putrefaction.

Increased Plasma Cardiac Troponin I in Live-Stranded Cetaceans: Correlation with Pathological Findings of Acute Cardiac Injury

Capture myopathy (CM), is a syndrome that occurs as the result of the stress during and after capture, handling, restraint, and transport of wild animals. Although CM has been described for many species of cetaceans, characterization of the acute cardiac injury - an important component of this syndrome - are still scarce. In this study, we firstly estimated a normal range for cardiac troponin I (cTnI) on cetaceans. Here, through biochemical analysis (especially of cTnI) and histopathological, histochemical, and immunohistochemical correlations with decreased troponin immunolabelling, we studied the cardiac injury in live-stranded cetaceans. Nine cetaceans which stranded alive on the Canary Islands (January 2016 - June 2019) were included in this study. Sampled individuals presented elevated values of plasma cTnI, which were correlated to histopathological lesions comprised of vascular changes and acute degenerative lesions. Immunohistochemically, injured cardiomyocytes showed a decreased intrafibrillar troponin immunoreaction. This is the first attempt to establish a normal baseline range for cTnI in cetaceans, and the first study comparing plasma biomarkers values with histopathological and immunohistochemical findings. This approach allowed us to demonstrate the degree of cardiac damage as a result of injury, consistent with ischemia-reperfusion lesions. The knowledge gained here could improve decision-making procedures during stressful situations, mainly in live-strandings, handling, and rehabilitation, thereby reducing the mortality of cetaceans.

Skeletal and Cardiac Rhabdomyolysis in a Live-Stranded Neonatal Bryde's Whale With Fetal Distress

The main objective of wildlife forensic investigation is to recognize pathologic changes and cause of death. Even though it may not always be possible to determine the specific illness and/or etiology, the description and subsequent interpretation of the injuries provide an invaluable understanding of pathology in cetacean post-mortem investigations. Although pathological studies have been previously reported in various cetacean species, such descriptions of the infraorder Mysticeti remain rare. A live-stranded neonatal Bryde's whale (Balaenoptera edeni) which subsequently died soon after the stranding, was assessed by physical exam, blood examination, gross necropsy evaluation, histopathology, and immunohistochemistry. It presented with elevated serum levels of creatine kinase, cardiac troponin I, urea, and creatinine. Microscopically, we observed keratin spicules (squamous epithelial cells) and areas of atelectasis in the lungs. Acute degeneration in the myocytes and cardiomyocytes were comparable to the findings previously described in cases of capture myopathy in live-stranded cetaceans. Immunohistochemistry biomarkers such as myoglobin, fibrinogen, and troponin were analyzed. Skeletal and myocardial damage has been documented in several cetacean species. However, this is the first reported case of skeletal and cardiac rhabdomyolysis associated with live-stranding in a newborn Bryde's whale that suffered from fetal distress.

Stress cardiomyopathy in stranded cetaceans: a histological, histochemical and immunohistochemical study

BACKGROUND

Free-living cetaceans are exposed to a wide variety of stressful situations, including live stranding and interaction with human beings (capture myopathy), vessel strikes, and fishing activities (bycatch), which affect their wellbeing and potentially lead to stress cardiomyopathy (SCMP).

METHODS

Here, the authors aimed to characterise SCMP of stranded cetaceans as an injury resulting from extreme stress responses, based on pathological analyses (histological, histochemical and immunohistochemical). Specifically, the authors examined heart samples from 67 cetaceans found ashore (48 live strandings, seven dead from ship collision and 12 dead from bycatch) on the coast of Spain, more specifically in the Canary Islands from 2000 to 2016 and Andalusia from 2011 to 2014.

RESULTS

The microscopic findings were characterised by vascular changes, acute or subacute cardiac degenerative necrotic lesions, interstitial myoglobin globules, and infiltration of inflammatory cells. Immunohistochemically, cardiac troponin I, cardiac troponin C and myoglobin were depleted, along with fibrinogen being expressed in the degenerated/necrotic cardiomyocytes. A perivascular pattern was also identified and described in the damaged cardiomyocytes.

CONCLUSIONS

This study advances current knowledge about the pathologies of cetaceans and their implications on conserving this group of animals by reducing mortality and enhancing their treatment and subsequent rehabilitation to the marine environment.

Mesenchymal stem cells pretreated with platelet-rich plasma modulate doxorubicin-induced cardiotoxicity

The cardiotoxic adverse effect of doxorubicin (DOX) is the major factor limiting its use. Recently, mesenchymal stem cells (MSCs) have been implicated in the preclinical studies of treatment of DOX-induced cardiotoxicity. The question is MSCs pretreated with platelet-rich plasma (PRP) have a better influence on DOX-induced cardiotoxicity compared to the influence of MSCs alone. Twenty-four Wistar rats were categorized into control, DOX-treated, MSC-treated, and PRP/MSC-treated groups. DOX was injected for two consecutive weeks. Light microscopic, biochemical markers (interleukin 10 (IL-10), tumor necrosis factor alpha (TNF-α), and creatine kinase-MB (CK-MB)), immunohistochemical (Bax, Bcl2, vascular endothelial growth factor (VEGF), and cardiac troponin-I (CT-I)), and oxidative/antioxidative markers (malondialdehyde (MDA)/superoxide dismutase (SOD)) were measured. Degenerative cardiac changes were detected in the DOX-treated group with complete loss of the architecture and coagulative necrosis. These changes were accompanied with the elevation of the serum level of CK-MB and loss of CT-I immunoreactivity. The major factors in the DOX-induced cardiotoxicity were the oxidative stress (elevated MDA/decreased SOD), inflammation (elevated TNF-α/decreased IL-10), and cardiac apoptosis (lower Bcl2, higher Bax, and lower Bcl2/Bax ratio). MSCs and PRP/MSCs attenuate DOX-induced cardiotoxicity. Better attenuation was observed in the PRP/MSC-treated group. PRP/MSC combination reduced greatly the MDA and TNF-α and increased IL-10, Bcl2/Bax ratio, and VEGF. PRP had no significant influence over the Bcl2, Bax, and SOD. In conclusion, DOX in its toxic dose induced myocardial injury. This destructive effect is related to oxidative stress, inflammation, and cardiac apoptosis. PRP/MSC possesses a better attenuation over the DOX-induced toxicity compared to MSC alone.

Sequence and time course of depletion of cardiac cellular proteins and accumulation of plasma proteins in rat early ischemic myocardium

In order to investigate the sequence and time course of fibronectin (Fn), fibrinogen (Fg), complement (C5), myoglobin (Mb), actin (HHF35), and desmin (Dm) for the diagnosis of early myocardial ischemia, the myocardial ischemia model was established in rats, the positive reaction areas of Fn, Fg and C5 and the depletion areas of Mb, HHF35 and Dm in the ischemic cardiomyocytes were studied with immunohistochemistry, image analysis technique and statistical system. The results showed that the depletion of Dm, HHF35 and Mb, and the positive staining of Fg and C5 in ischemic cardiomyocytes were found as early as 15 min after the myocardial ischemia, but the positive staining of Fn occurred till 3 h after myocardial ischemia. With the prolongation of ischemia, the areas of the depletion of Dm, HHF35, Mb and the positive staining of Fg, C5 and Fn gradually enlarged. It is suggested that all the six immunohistochemical markers are more sensitive than routine H&E staining, and that Dm, HHF35, Mb, Fg, C5 are more sensitive markers than Fn for detection of early myocardial ischemia.

Immunohistochemical study on dystrophin expression in CAD-related sudden cardiac death: a marker of early myocardial ischaemia

The aims of this study were to assess if dystrophin can be a tool for the forensic evaluation of sudden cardiac death due to coronary atherosclerotic disease (CAD) and particularly if it can be a marker of early myocardial ischaemia. Then in this investigation, the dystrophin was compared to C5b-9 and fibronectin to analyze if there are some differences in the expression of these proteins. Two groups of CAD-related sudden cardiac death, respectively the group 1 with gross and/or histological evidence and the group 2 with no specific histological signs of myocardial ischaemia were used. A third group formed by cases of acute mechanical asphyxiation was used as a control. The immunohistochemical staining by dystrophin, C5b-9 and fibronectin antibodies was performed. Loss of sarcolemmal dystrophin was observed in different degrees according to more or less significant histological evidence of myocardial ischaemia. Moreover, the comparison between loss of dystrophin expression and fibronectin positivity showed significant differences in group 2. The results suggested that dystrophin can be used in forensic diagnosis of CAD-related sudden cardiac death and as marker of early myocardial ischaemia.

Fatal poisoning by butane sniffing: A forensic analysis and immunohistochemical detection of myocardial hypoxic damage

Although less widespread than twenty years ago, inhalant abuse remains an on-going problem, whose incidence among U.S. teenagers and young adults ranges from 10 to 15%. Death due to the inhalation of vapor from halogenated hydrocarbons is a well-known phenomenon, yet few cases of fatal butane-gas poisoning have been described. Many cases of volatile substance abuse in prison populations have been reported: drug-addicted inmates often resort to this alternative practice when unable to get their habitual drugs of abuse. A similar pattern occurs especially among adolescents. The study herein described was conducted including all cases of fatal acute intoxication of butane gas examined from 2007 to 2015 at the Institute of Legal Medicine and Forensic Sciences of the University of Genoa. In the absence of overt and specific macroscopic and histological findings indicating cause and pathological mechanism of death, we aimed to assess whether recent cardiac lesions were detectable by way of immunohistochemical (IHC) analysis. Specifically, fibronectin and troponin C expression in myocardial tissues were investigated in deaths from acute butane-gas poisoning so as to better define the underlying pathological mechanisms. IHC findings were indicative of hypoxic cardiac damage. In all cases, positivity to fibronectin and mildly to moderately reduced troponin C expression in cardiac muscle cells were immunohistochemically ascertained.

Immunohistochemical detection of early myocardial infarction: a systematic review

The postmortem diagnosis of early myocardial infarction is a challenge for forensic pathologists because the routine histology is neither specific. Many authors have suggested the use of the immunohistochemistry to fill the gaps in the histological diagnosis of early myocardial infarction. This review aims to analyse advances of immunohistochemical detection of early cardiac damage due to ischaemia. To this purpose, we reviewed experimental studies that investigated immunohistochemical markers and their estimated timing of expression. The review was performed according to specific inclusion and exclusion criteria, and a total of 23 studies assessing the immunohistochemical markers for the diagnosis and timing of early myocardial infarction were identified. The literature review highlights that the analysed markers are complement components, others being inflammatory mediators, cardiac cell proteins, plasma proteins, stress or hypoxia-induced factors and proteins associated with heart failure. All studies demonstrate the effectiveness of the tested markers in the early detection of myocardial infarction in both animal and human samples.

Role of Cardiac Myocytes Heart Fatty Acid Binding Protein Depletion (H-FABP) in Early Myocardial Infarction in Human Heart (Autopsy Study)

BACKGROUND:

Many immunohistochemical markers have been used in the postmortem detection of early myocardial infarction.

AIM:

In the present study we examined the role of Heart-type fatty acid binding protein (H-FABP), in the detection of early myocardial infarction.

MATERIAL AND METHODS:

We obtained samples from 40 human autopsy hearts with/without histopathological signs of ischemia.

RESULTS:

All cases of definite and probable myocardial infarction showed a well-defined area of H-FABP depletion. All of the control cases showed strong H-FABP expression, except two markedly autolysed myocardial samples that showed affected antigenicity.

CONCLUSION:

Thus, we suggest H-FABP as being one of the valuable tools facing the problem of postmortem detection of early myocardial infarction/ischemia, but not in autolysis.

Immunohistochemical analysis of cardiac troponin inhibitor in an experimental model of acute myocardial infarction experimental model and in human tissues

Acute obstruction of coronary arteries leads to acute myocardial infarction (AMI), which causes unexpected death in humans. However, AMI cannot be easily detected in forensic examinations with traditional hematoxylin and eosin (H&E) staining. We analyzed whether cardiac troponin inhibitor (CTnI) could serve as a sensitive and specific early marker for diagnosing AMI in forensic medicine. We established an AMI model in rabbits by ligating the left ventricular branch and observed CTnI expression with immunohistochemistry after different ligation times. We found increased CTnI staining at the 0.5-h time point and depletion of CTnI staining with a 1-h ligation. The areas in which CTnI staining was depleted as seen with immunohistochemical analysis were consistent with the results of H&E staining. Next, human myocardium tissues from 30 persons who died from AMI and were subsequently examined in our forensic center were studied using immunohistochemistry with an antibody to human CTnI. Areas of infarction also showed depletion of CTnI staining. These findings suggested that immunohistochemical detection of CTnI is earlier, more sensitive, and myocardial tissue - specific as compared with H&E staining. CTnI may serve as an ideal marker for diagnosing AMI in forensic investigations.

Can early myocardial infarction-related deaths be diagnosed using postmortem urotensin receptor expression levels?

PURPOSE

Myocardial infarction (MI) is one of the most prevalent causes of sudden adult death. It is difficult to diagnose early MI postmortem because there are no typical or characteristic changes in morphology. In this study, changes in the level of the mRNA for the urotensin receptor (UR) were investigated postmortem to determine the suitability of UR as a biomarker for diagnosis of early MI after death.

METHODS

An MI rat model was developed by injecting rats with isoproterenol (ISO) (lethal dose 850 mg/kg) or normal saline (control group). The hearts of rats in the control and ISO-induced MI groups were harvested at 0, 1, 3, 6, 12, 24, 48, and 72 h (h) postmortem. The hearts were then immediately submerged in 1 mL of RNA stabilization solution and stored at 4 °C for <1 week before RNA extraction. Relative UR expression analysis was performed using the StepOne Plus Real Time PCR System with cDNA synthesized from rat heart.

RESULTS

Postmortem UR mRNA expression was higher in the ISO-induced MI group than in the control group, at both 4 and 20 °C, at all of the time points examined except 72 h postmortem (p < 0.0001). The largest increases were observed at ambient temperature and 6 h postmortem.

CONCLUSIONS

Based on our findings, increased postmortem UR expression could serve as a biomarker to aid diagnosis of early MI.

Immunohistochemical detection of S100A1 in the postmortem diagnosis of acute myocardial infarction

Background

Sudden cardiac death resulting from acute myocardial infarction (AMI) constitutes a significant percentage of the caseload for forensic and clinical pathologists. When sudden death occurs at an early stage (<6 h), pathologists experience difficulty in the postmortem diagnosis of AMI. Because of the specific tissue distribution of S100A1 and its relationship with acute ischemic heart disease, this study aimed to evaluate the performance of S100A1 in the postmortem diagnosis of AMI.

Methods

We constructed a rat model of AMI through permanent ligation of the left anterior descending coronary artery (LAD) to investigate the depletion of S100A1 from ischemic cardiomyocytes by immunohistochemistry and measuring S100A1 plasma concentrations by enzyme-linked immunosorbent assay at varying post-infarction intervals. In addition, immunohistochemical staining of S100A1 for definite infarction, suspected early infarction, and in normal human hearts, was also performed to test its practical feasibility for postmortem diagnosis of AMI at an early stage.

Results

As early as 15 min after ligation of the LAD, depletion of S100A1 was observed in ischemic cardiomyocytes, and S100A1 plasma concentration was also significantly higher than that of the sham-operated group (P < 0.001). With continuation of the occlusion time, the depleted areas of S100A1 further expanded and S100A1 plasma concentrations further increased. For autopsy material, all human cases of definite myocardial infarction and suspected early infarction showed well-defined areas without S100A1 staining. None of the normal human cases showed diffuse depletion of S100A1.

Conclusion

Our results suggest that immunohistochemical detection of S100A1 is useful for the postmortem diagnosis of AMI at an early stage.

Virtual slides

The virtual slide(s) for this article can be found here:

http://www.diagnosticpathology.diagnomx.eu/vs/4366650979519818

Bioreducible polymer-transfected skeletal myoblasts for VEGF delivery to acutely ischemic myocardium

Implantation of skeletal myoblasts to the heart has been investigated as a means to regenerate and protect the myocardium from damage after myocardial infarction. While several animal studies utilizing skeletal myoblasts have reported positive findings, results from clinical studies have been mixed. In this study we utilize a newly developed bioreducible polymer system to transfect skeletal myoblasts with a plasmid encoding vascular endothelial growth factor (VEGF) prior to implantation into acutely ischemic myocardium. VEGF has been demonstrated to promote revascularization of the myocardium following myocardial infarction. We report that implanting VEGF expressing skeletal myoblasts into acutely ischemic myocardium produces superior results compared to implantation of untransfected skeletal myoblasts. Skeletal myoblasts expressing secreted VEGF were able to restore cardiac function to non-diseased levels as measured by ejection fraction, to limit remodeling of the heart chamber as measured by end systolic and diastolic volumes, and to prevent myocardial wall thinning. Additionally, arteriole and capillary formation, retention of viable cardiomyocytes, and prevention of apoptosis was significantly improved by VEGF expressing skeletal myoblasts compared to untransfected myoblasts. This work demonstrates the feasibility of using bioreducible cationic polymers to create engineered skeletal myoblasts to treat acutely ischemic myocardium.

Determination of Cardiac Troponin I in the Blood and Heart of Calves with Foot-and-Mouth Disease

The current study was designed to determine the changes of the cardiac troponin I (cTnI) expression in blood and tissue during the myocardial degeneration in calves with foot-and-mouth disease (FMD). Seventeen crossbred calves presenting pathological signs for FMD confirmed by viral analysis were studied. A biochemistry panel and immunohistochemistry were performed on 17 diseased calves and 7 calves used as controls. Creatine kinase (CK), CK-myocardial band (CK-MB), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) activities were analyzed for both groups. Cardiac troponin I levels were measured by a commercially available enzyme-linked immunosorbent assay kit. Mean cTnI (14.8 ± 1.9 ng/ml) concentration and CK (573 ± 407 U/l), CK-MB (238 ± 37 U/l), AST (84 ± 7), and LDH (298 ± 29 U/l) activities were higher in FMD cases compared with controls. Immunohistochemistry revealed loss or depletion of cTnI expression in myocardium of all cases. None of the 7 controls showed loss of cTnI expression. Increased serum cTnI concentration correlated with myocardial injury and loss of cTnI immunolabeling in cardiomyocytes of calves with FMD.

Sudden cardiac death and myocardial ischemia indicators: a comparative study of four immunohistochemical markers

The postmortem diagnosis of acute myocardial infarction represents a current challenge for forensic pathologists, particularly when death occurs within minutes to a few hours after the ischemic insult. Among the adult population the single most important cause of sudden cardiac death (SCD) is the well-known atherosclerotic coronary artery disease, commonly asymptomatic or unrecognized. The recognition of early myocardial damage using routine hematoxylin and eosin (H&E) staining is possible only if death has occurred at least 6 hours after the onset of the ischemic injury. The usefulness of immunohistochemical markers to the diagnosis of early myocardial damage has been recently suggested because most of them can be visible even serologically as early as few minutes after the beginning of the symptoms. To evaluate the usefulness of plasma and cellular antigens, their distribution patterns have been studied among a group of 18 SCD cases in which a myocardial ischemia was strongly suspected. For the present study, 4 markers have been selected on the basis of their different diagnostic potential as follows: among the plasma markers the C5b-9 and fibronectin, among the cellular markers the myoglobin and cardiac troponin. The results show that only the study of multiple markers such as those selected can provide enough evidence of myocardial ischemia and/or necrosis, supporting the final diagnosis of SCD. No single immunohistochemical staining is ideal for diagnosing early myocardial ischemia but a set of markers can improve the ability of forensic pathologists to detect ischemic areas when no macroscopic or microscopic evidence of necrosis is available. However, the interpretation of data obtained in each individual cannot be isolated from the overall assessment of the factors (cardiopulmonary resuscitation and/or agonal artifacts) that can affect the expression of each marker.

Heart fatty acid binding protein as a marker for postmortem detection of early myocardial damage

Depletion of heart fatty acid binding protein (H-FABP) from cardiomyocytes with varying post-ischemia intervals was studied in acute myocardial infarction (AMI) model of rat, and 22 human autopsy cases were studied with streptavidin-peroxidase conjugated method (S-P). It was observed that as early as 15 min after ischemia, the depletion of H-FABP could be detected in model rats. With the ischemic time prolonged, the depletion of H-FABP was more and more evident. In all human cases with myocardial infarction, absent H-FABP staining could be found in infarcted area. And in some suspected early myocardial infarction cases, depletion of H-FABP staining could be demonstrated in areas that showed normal hematoxylin-eosin (HE) staining. The blood samples from model rats before ligation, at varying post-ischemia intervals and various postmortem time were measured for plasma concentration of H-FABP with enzyme-linked immuno-sorbent assay (ELISA) method. At 15 min after myocardial ischemia, the concentration of H-FABP was 4 times higher (546.0+/-85.3 microg/l) than that of the baseline level (103.7+/-94.1 microg/l). With the continuation of ischemic time, the concentration of H-FABP increased and peaked at 4 h (1953.5+/-405.3 microg/l), then decreased. The plasma concentration of H-FABP decreased slightly with postmortem time, but was still significant higher at any postmortem intervals than that of baseline level within 48 h after death. The results suggest that H-FABP staining can detect very early ischemic damages in human myocardium and the elevated plasma concentration of H-FABP in rat was an indicator of AMI, which was not affected by autolysis.

The relevance of the detection of troponins to the forensic diagnosis of cardiac contusion

The forensic diagnosis of cardiac contusion has hitherto been based mainly on anamnesis, concomitant thoracic injuries and the detection of macroscopic changes to the heart. Parallel histological and serological investigations of the heart-specific troponins have been conducted with varying results. This paper aims to show whether heart-specific troponins are suitable as a means of securing the diagnosis in proven cases of cardiac contusion and of determining which of the three heart-specific troponins cTnT, cTnI and cTnC are most significant in serology and histology for postmortem diagnosis. In the study, 25 cases of known cardiac contusion and 11 controls without vital myocardial trauma taken from autopsy material were prospectively investigated. Investigation of the venous serum revealed significant differences in the concentrations of the case and control groups for troponin T (mean value 5.5056 versus 0.4982; p=0.014), for troponin C (mean value 263.9280 versus 68.5640; p=0.001) and for troponin I (mean value 1404.0560 versus 36.1650; p=0.003). In histology there are also significantly different depletions between the groups investigated (cTnT: p=0.002; cTnC: p=0.003; cTnI: p<0.001) taking into account the autolysis time.

Diagnostic efficacy of biochemical markers in diagnosis post-mortem of ischaemic heart disease

In forensic medicine, there is a need for more sensitive biochemical markers for the post-mortem diagnosis of acute myocardial infarction. A study of the distribution of biochemical markers in different fluids is of great significance in post-mortem diagnosis, because their distribution depends on the location of tissue damage and release kinetics. The aim of this study is to compare the sensitivities and specificities of creatine kinase-MB (CK-MB), myoglobin and cTnI in serum and pericardial fluid for the post-mortem diagnosis of acute myocardial infarction (AMI). We studied 188 cadavers selected during 1 year from medicolegal autopsies. The groups were as follows: (1) myocardial infarction (n = 52); (2) asphyxia (n = 59); (3) multiple trauma (n = 41); (4) natural deaths excluding myocardial infarction (n = 36). We obtained statistically significant differences in pericardial fluid for all the biochemical markers, the highest levels being obtained in the group of cadavers who had died from myocardial infarction. A common factor is the high negative predictive value found in biochemical markers, which is contrary to the findings obtained in clinical practice, when the percentages of sensitivity are very high.

Myocardial tissue troponins T and I. An immunohistochemical study in experimental models of myocardial ischemia

BACKGROUND

Cardiac troponins T (cTnT) and I (cTnI) are proven diagnostic and risk stratification biomarkers in patients with acute coronary syndromes. To date, no immunohistochemical studies have been performed which allow visualization of the time course and pattern of myocardial troponin egress from the myocardium during the early evolution of ischemic injury in experimental systems.

METHODS

We studied archival formalin-fixed, paraffin-embedded myocardium from 50 experimental animals (dogs, pigs and rats) that had undergone permanent coronary occlusion (n = 34) for 0.5-6 h or occlusion of 0.75-6 h followed by reperfusion (n = 16). Histologic sections that included ischemic and nonischemic myocardium were studied by immunohistochemistry with three different antibodies to human cTnI and one to cTnT, using a standard avidin-biotin-peroxidase system.

RESULTS

All antibodies detected cTnT or cTnI in normal myocardium and its loss from necrotic myocardium, in some cases as early as 30 min after coronary occlusion, before histologic evidence of necrosis was present. Loss was nonuniform, being greater at the periphery of the infarcts then at their central regions. Usually, loss of cTnT appeared greater than loss of cTnI. With reperfusion, findings were similar to those after permanent occlusion, except that there was a greater contrast between loss at the periphery compared to the loss in the central region. Considerable residual staining persisted for hours after occlusion, indicating delayed release over time, concordant with sustained serum elevations in patients with acute myocardial infarction. No loss of staining was observed in nonnecrotic myocardium.

CONCLUSIONS

Immunohistochemical staining using antibodies to human cTnT and cTnI can be used to visualize cardiac troponins and document their loss in histologic sections of myocardium in different animal species. Loss of cTnT and cTnI occurs very early following ischemic injury and may precede histologic evidence of necrosis, but does not occur in myocardium that is not necrotic. Immunohistochemical staining of hearts for cTnT and cTnI can assist in the often difficult recognition of myocardial necrosis at autopsy, in patients suspected of dying from acute myocardial ischemia.

Is immunohistochemistry a useful tool in the postmortem recognition of myocardial hypoxia in human tissue with no morphological evidence of necrosis?

Myocytes in the border zone of myocardial infarction are under severe hypoxia without characteristic morphology of necrosis, and show ultrastructural features similar to those seen within the first hours after coronary occlusion. This study was carried out to evaluate the possibility that immunohistochemical methods could be used for the early diagnosis of myocardial infarction by detecting areas of hypoxia. Nineteen human sections of formalin-fixed paraffin-embedded myocardial samples showing a necrotic area and its border were submitted to immunohistochemical staining with the markers antimuscle actin, antimyoglobin, antitroponin T, antifibronectin, and anticomplement component C9. Sections were also subjected to azan trichrome and hematoxylin-basic fuchsin-picric (HBFP) staining techniques. Immunohistochemistry and azan trichrome showed that in the border zone there was a pattern of reaction intermediate between the infarcted area and the normal myocardium. The HBFP failed to distinguish these two areas. In conclusion, immunohistochemistry and azan trichrome can recognize myocardial hypoxia. Because hypoxia is an invariable condition in infarction, these techniques can be used to confirm suspected cases of myocardial infarction in which necrosis is not yet evident. However, considering that agonal states may be associated with generalized hypoxia, further studies are needed to confirm the reliability of this procedure in the earlier phases of myocardial infarction.

Importance of microembolization and inflammation in atherosclerotic heart disease

Considerable evidence now exists that inflammation is a central component of events that initiate and propagate an acute coronary syndrome. This process evokes the potential for embolization, which occurs more often than previously suspected, and imparts poor cardiovascular prognosis. Recent development of techniques to detect inflammation and embolization represents an important advance. In addition, therapies that diminish occurrence of these phenomena such as aspirin, statins, angiotensin converting enzyme (ACE) inhibitors, and IIb/IIIa receptor antagonists have been shown to improve outlook.

Acp. Best practice no 155. Pathological investigation of deaths following surgery, anaesthesia, and medical procedures

The pathological investigation of deaths following surgery, anaesthesia, and medical procedures is discussed. The definition of "postoperative death" is examined and the classification of deaths following procedures detailed. The review of individual cases is described and the overall approach to necropsy and interpretation considered. There are specific sections dealing with the cardiovascular system (including air embolism, perioperative myocardial infarction, cardiac pacemakers, central venous catheters, cardiac surgery, heart valve replacement, angioplasty, and vascular surgery); respiratory system (postoperative pneumonia, pulmonary embolism, pneumothorax); central nervous system (dissection of cervical spinal cord), hepatobiliary and gastrointestinal system; musculoskeletal system; and head and neck region. Deaths associated with anaesthesia are classified and the specific problems of epidural anaesthesia and malignant hyperthermia discussed. The article concludes with a section on the recording of necropsy findings and their communication to clinicians and medicolegal authorities.