Objective: To investigate the pathological features and causes of sudden death clustered in family or village in Yunnan province so as to provide the morphological basis for exploring its etiology and medical intervention.
Methods: Autopsy was performed on 29 cases of clustered in family or village in Yunnan province during the period 1991-2006, 16 males and 13 females, aged 32 (8-69), accounting for 10.2% of whole sudden unexpected deaths occurring in the same period. The heart, lung, liver, spleen, brain, kidney, intestinal tract, and other organs were examined macroscopically and histologically, including a study of cardiac conduction system in 5 cases. Pathological diagnosis of myocarditis was based on the Dallas Criteria and World Heart Federation's consensus while the histological evaluation of Keshan disease referred the China national guideline for pathological diagnosis of Keshan disease.
Results: Based on the main pathological changes and the causes of death, these cases were classified into seven groups (group A-G). Group A comprised 11 cases (38%) with lymphocytic myocarditis accompanied with focal myocardial necrosis or degeneration. Group B comprised 3 cases (10%) with neutrophil myocarditis accompanied with focal myocytolysis or coagulation necrosis. Group C comprised 4 cases (14%) with arrhythmogenic right ventricle cardiomyopathy in which fatty infiltration of myocardium was the only pathological finding. Group D comprised 2 cases (7%) with ischemic heart disease in which fresh or old foci of myocardial infarction were found but coronary stenosis was shown only in one case. Group E comprised 2 cases (7%) with left ventricle hypertrophy and obstructive muscle bundle in the outflow of left ventricle. Group F comprised 2 cases (7%) with allergic bronchitis or chronic bronchitis and pulmonary emphysema. Group G comprised the remaining 5 cases (17%) without any pathological finding that could explain sudden death. No cases suffered with Keshan disease and dilated cardiomyopathy. Focal but not diffuse inflammatory infiltration was the prominent histological feature of myocarditis in Yunnan cases. Among the five cases with histological examination of cardiac conduction system, 2 cases were detected to suffer from acute hemorrhage in His bundle and its left branching site, and the atrioventricular node of 1 case was involved. Different pathological changes coexisted in 4 pairs of family members as a cluster of sudden deaths. 3 of 4 first deaths had focal myocarditis and the other one had chronic infection. But 3 secondary deaths had myocardial ischemia and the other one had arrhythmogenic right ventricle cardiomyopathy. Pulmonary edema, acute respiratory infection and congestive or ischemic liver necrosis were found in some cases simultaneously.
Conclusion: The pathological changes of the cases of clustered sudden death in Yunnan province are various, such as myocarditis, myocardial dysplasia and the other lethal heart-lung disorders. No case of Keshan disease has been found. Arrhythmogenic right ventricle cardiomyopathy and other foundational heart diseases might act as a background. It is very hard to contribute only one etiological factor to the clustering of sudden death in Yunnan. It was most likely that multiple factors cluster and trigger an outbreak of death in a definite time and space.