A Two Year Autopsy Study on Coronary Artery Stenosis

Introduction

Coronary artery disease, popularly quoted as `The Captain of the Men of death’ is the most common cause of unanticipated deaths [1]. 17.7 million people die each year from cardiovascular disease, an estimated 31% of all deaths worldwide of which more than 75% occur in low- income and middle-income countries [2]. This reveals the magnanimity of the problem. These deaths are categorised as natural deaths but they carry medicolegal significance as they may cause death in young and asymptomatic individuals raising suspicion of foul play. In some cases, especially geriatric population where some degree of coronary artery stenosis is nearly always present, the cause of death can be inaccurately concluded as “coronary artery disease”. Road traffic accidents and death due to assault may be complicated by concurrent presence of coronary artery stenosis, making the inference regarding cause of death similar to the question- ‘the egg came first or the hen’.

Material and Methods

The study was conducted in a span of two years on 120 autopsies performed at Sri Aurobindo Medical College & P.G.I, Indore. The aim of this research was to note the severity of coronary artery stenosis and its relation with parameters like age, body mass index and association with myocardial ischemia.

An elaborate history was taken from the relatives, data from hospital records was procured and a detailed autopsy was conducted where the heart and its coronaries were meticulously observed and dissected. The left main, the left circumflex, the anterior descending, the right main and the posterior descending coronaries were examined by cutting at regular intervals (2-3 mm) for the degree of stenosis, atheromatous plaque, superimposed thrombus, calcification or hemorrhage.

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Figure 1: Section of heart stained by T.T.C method reveals a part of normal myocardium which reacts with the buffered oxidation reduction reagent in solution and gets stained. The stained myocardium is red. There is loss of endogenous substrates, coenzymes and dehydrogenases in the infracted tissue and therefore there is no reaction with the regents and hence the infarcted area remains unstained.

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This was followed by cutting the heart into transverse slices 10 mm thick, proceeding upwards from apex to valve and examining them for gross signs of ischemia like hyperemia, yellowing, mottling, scarring. If ischemia was suspected on gross examination, T.T.C test or N.B.T test was performed (Figures 1-4), which is based on the principle that the normal myocardium reacts with TTC reagent to give red stain and with Nitro B.T to give reddish blue stain in solution. However due to the loss of enzymes and vital reaction, the infracted myocardium does not react with the reagent and hence remains unstained.

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Figure 3 (a, b, c): Histopathology of the hyperemic areas of myocardium reveals ischemic changes.

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Discussion

Some degree of stenosis was noted in all victims above the age of 30 years, the youngest male and female subjects being 21 years of age. This is in agreement with Strong & McGill [3]. Morris who concluded that there is no straightforward association between atherosclerosis and ischaemic heart disease, which was also found in our study [4]. This however is in conflict with studies by Crawford, Dexter, Teare Strong and McGill [3, 5]. A direct link was noted between the sex of the subject (more in males) and myocardial ischemia, which is similar to findings by Strong and McGill3 while this is contrary to a study by Roberts, Moses and Wilkins [6, 7].

While trying to correlate myocardial ischemia with the grade of stenosis in the coronary arteries, no simple correlation could be deduced, as even with just 25% coronary artery stenosis, ischemic changes were found.

In the current study, T.T.C staining technique gave a positive reaction for 5 out of 120 hearts studied, thus revealing infracted area of myocardium in these 5 hearts, with the earliest infarct to be detected being of half hour duration, which was similar to Fine & also Andersen and Hensen [8, 9]. Sandritter and Jestadt, Mc Vie, Nachals and Shnikta and Ramkisson, studies could detect ischemic changes 8 hours after onset of symptoms [10, 11, 12, 13].

4 hearts out of 120 cases in the current study, weighed more than 400 gms, of which 2 hearts did not reveal ischemic changes, while the other two had transmural infarcts in left ventricle.

Results & Conclusion

Ischemic changes in the myocardium were detected by gross histochemical staining & histopathology in a total of 5 cases out of the 120 hearts studied.

All five were males in the age group of 35 to 40 years. In 1 case the subject was underweight, in 3 cases within normal limits of BMI.

Hence, increasing incidence of stenosis and ischemic changes is seen in young, thin built males with no significant correlation between degree of stenosis and ischemic changes.

Through this paper we want to highlight the uptrend in cases of sudden death from coronary artery disease in seemingly healthy young males. In such cases, imminent death from cardiac cause is phantasmal. Thus ante mortem investigations for a timely diagnosis which could possibly be life saving are missed and the same continues after death, leading to an obscure autopsy. Perspicacity is the need of the hour.