Arrhythmogenic potential of exercise-induced myocardial ischaemia

Comparison of Histological Changes in Tissue Specimens Kept in Tap Water, River Water and Seawater for Different Intervals of Time

BACKGROUND

Forensic pathologists find it difficult to ascertain the actual reason for death and the actual mode of death in drowning cases. It is commonly acknowledged that not all people whose dead bodies are found in water perished from drowning. The medico-legal inquiry includes an important component that examines dead bodies collected from the water. The corpse's time in the water continues to be the main concern. This aids in determining the time of death, which is crucial to any medico-legal investigation. The traditional histological analysis of hematoxylin and eosin (H&E)-stained oral soft tissue can be crucial in the assessment of this feature. Hence, this study was done to compare histological changes in the tissue specimens kept in tap water, river water, and seawater for different intervals of time.

MATERIALS AND METHODS

One hundred eighty specimens were obtained from 180 dead bodies and divided randomly into three categories. Category A consisted of 60 specimens submerged in tap water, Category B of 60 specimens submersed in river water, and Category C consisted of 60 specimens submerged in seawater. The specimens underwent routine histological processing and H&E staining. The microscopic evaluation of specimens was carried out at two hours and on the first, second, third, fourth, and fifth days of submersion. Details were recorded regarding the structural changes, cellular changes, connective tissue changes, changes in the basement membrane, and intensity of H&E staining. Once the process of routine histological processing and H&E staining was completed for each study specimen, an evaluation of microscopic changes in the tissue was made.

RESULTS

The present study revealed that seawater preserved tissue best and for a longer period than river water and tap water. River water preserved tissue better than tap water. In pathologic tissue, details were preserved for much longer. It was noted that in squamous cell carcinoma, connective tissue was destroyed earlier than epithelium, in contrast to normal tissue where epithelium was destroyed before connective tissue.

CONCLUSION

This study indicates that the medium of submersion in drowning victims affects the histopathological features. The time of death is an important aspect of forensic investigation. Considering this, all cases of drowning should be very carefully evaluated, and the medium taken into consideration while determining the time of death, as tissue degrades faster in freshwater than in seawater.

Forensic investigation of submersion deaths

CONTEXT

The diagnosis of the cause and the establishment of the manner of death in submersion cases are routine challenge for forensic pathologists as it presents considerable diagnostic difficulties.

OBJECTIVE

To concisely review the main questions during a submersion death investigation and to give the respective documented answers.

DATA SOURCES

The search strategy included a literature search of PubMed, Medline and Google Scholar databases, as well as a review of the cited references by the identified studies and a hand search of relevant textbooks and reference works.

CONCLUSIONS

A complete autopsy, histopathological examination and full toxicological screening are important to determine whether death indeed followed submersion in the water, or to see whether any natural disease or substance use have contributed or caused death. In ambiguous situations, the co-estimation of circumstantial evidence may be of invaluable importance toward the conclusion concerning the cause and the manner of death. The thorough forensic investigation of the submersion deaths not only serves the justice administration, but it also presents considerable benefits for the public health.

Functional and prognostic significance of exercise-induced ventricular arrhythmias in patients with suspected coronary artery disease

Our aims were to assess (1) the relation between exercise-induced ventricular arrhythmia (VA) and myocardial wall motion abnormalities during exercise echocardiography in patients with suspected coronary artery disease (CAD), and (2) the effect of this relation on outcome. We studied the clinical and prognostic significance of exercise-induced VA in 1,460 patients (mean age 64 +/- 10 years; 867 men) with intermediate pretest probability of CAD and no history of previous myocardial infarction or revascularization who underwent exercise echocardiography. Exercise-induced VA occurred in 146 patients (10%). Compared with patients without VA, those with VA had a greater prevalence of abnormal exercise echocardiographic findings (48% vs 29%, p = 0.001) and ischemia on exercise echocardiography (39% vs 22%, p = 0.001), greater increase in wall motion score index with exercise (0.14 +/- 0.28 vs 0.06 +/- 0.18, p <0.0001), and a greater percentage of abnormal segments with exercise (21 +/- 30% vs 9 +/- 19%, p <0.0001). During follow-up (median 2.7 years), cardiac death and nonfatal myocardial infarction occurred in 36 patients. In multivariate analysis of combined clinical and exercise stress test variables, independent predictors of cardiac events were exercise-induced VA (chi-square 4.7, p = 0.03) and exercise heart rate (chi-square 18, p = 0.0001). The percentage of abnormal myocardial segments with exercise echocardiography was the most powerful predictor of VA (chi-square 31, p = 0.0001) and cardiac events (chi-square 15, p = 0.0001). In patients with suspected CAD, exercise-induced VA is associated with a greater risk of cardiac death and nonfatal myocardial infarction. This risk is attributed to the relation between VA and the extent and severity of left ventricular functional abnormalities with exercise.

Relation among exercise-induced ventricular arrhythmias, myocardial ischemia, and viability late after acute myocardial infarction

This study assesses the relation between exercise-induced ventricular arrhythmia (VA) and scintigraphic markers of myocardial ischemia and viability in patients referred for exercise stress testing late after acute myocardial infarction. We studied 171 patients (144 men, age 57 +/- 10 years) with resting wall motion abnormalities by exercise stress testing in conjunction with methoxyisobutyl isonitrile (MIBI) single-photon emission computed tomography at a mean of 4.1 years after myocardial infarction. Ischemia was defined as reversible perfusion abnormalities. Myocardial viability was considered in myocardial segments with resting wall motion abnormalities in the presence of normal perfusion, a reversible defect or a fixed defect with regional MIBI uptake > or = 50% of maximal uptake. Exercise-induced VA occurred in 46 patients (27%). Patients with VA had a higher prevalence of infarct-related artery stenosis (43 [93%] vs 93 [74%], p < 0.01), peri-infarction ischemia (32 [70%] vs 54 [43%], p < 0.005), and ischemia in > or = 2 vascular regions (20 [43%] vs 27 [22%], p < 0.01) than patients without VA. Reversible defects were detected in 39 of 97 dyssynergic segments (40%) in patients with versus 40 of 248 dyssynergic segments (16%) in patients without VA (p < 0.0001). In dyssynergic segments without reversible perfusion abnormalities, the percent resting MIBI uptake was > or = 50% in 39 of 58 segments (67%) in patients with versus 63% in 131 of 208 segments in patients without VA (p = NS). The percentage of viable segments was 80% and 69% in patients with and without VA, respectively (p < 0.05). It is concluded that patients with exercise-induced VA late after myocardial infarction have a higher prevalence of ischemia in the peri-infarction zone and in multivessel distribution. Myocardial ischemia in the dyssynergic myocardium appears to be a major mechanism underlying the occurrence of VA in these patients.

Influence of atenolol on the relationship between heart rate and QT interval in patients with exercise-induced myocardial ischemia

The aim of this study was to analyze the relationship between heart rate and QT interval (HR-QT) during exercise in control subjects (Group A) and in patients with coronary artery disease (CAD) with effort angina and without previous myocardial infarction (MI) (Group B). The diagnosis of CAD was confirmed by coronarographic examination. The correlation HR-QT was significant (p < 0.001) in both groups on effort and at recovery. The analysis of the regression HR-QT was carried out separately, both on effort in upright position and at rest in supine position, to avoid the influence of posture on QT length. During effort, the regression line showed lower slope and intercept values in Group B (p < 0.001) than those for Group A. A similar behavior was also observed at rest. Thus, at the highest heart rate, where ECG signs of ischemia (ST depression > 1 mm) frequently occurred, a longer QT interval was present in Group B. Moreover, in Group B, the QT interval in the presence of ECG signs of ischemia was significantly longer (p < 0.01) than in Group A at comparable heart rates both on effort and at rest, thereby confirming the result obtained by comparing both regression lines. The same effort protocol was repeated in Group B patients after acute administration of atenolol 100 mg per os. After atenolol administration, the analysis of the regression HR-QT in Group B clearly showed a shorter QT interval than that obtained in washout period during the baseline test at the highest heart rates where the ECG frequently showed signs of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)