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Histopathological study of hypertrophic cardiomyopathy with progression to left ventricular dilatation
C Yutani1, M Imakita, H Ishibashi-Ueda
1Dept. of Internal Medicine, National Cardiovascular Center, Osaka.
Insights
Fatal heart failure in hypertrophic cardiomyopathy (HCM) is linked to widespread myocardial disarray and extensive fibrosis. This study investigated seven cases, revealing significant fibrosis and inflammation in the left ventricle, particularly in the lateral wall.
Area of Science:
- Cardiovascular Pathology
- Cardiac Morphology
- Myocardial Diseases
Background:
- Fatal congestive heart failure can develop in patients with hypertrophic cardiomyopathy (HCM).
- Widespread myocardial disarray and fibrosis are implicated in cardiac dysfunction.
Purpose of the Study:
- To morphologically investigate the hearts of patients with fatal congestive heart failure and dilated left ventricles, particularly those with hypertrophic cardiomyopathy.
Main Methods:
- Morphological investigation of seven cases of fatal congestive heart failure.
- Histological analysis of myocardial disarray, fibrosis, cell infiltration, and small artery morphology in the left ventricle.
Main Results:
- All seven cases exhibited widespread myocardial disarray and massive fibrosis, with mean fibrosis areas of 40.6% (upper) and 59.4% (lower) left ventricle.
- Fibrosis was most extensive in the lateral wall, followed by anterior, posterior, and interventricular walls.
- Cell infiltration severity correlated with fibrosis, being most prominent in the subepicardial layer. Intramural small artery thickening was observed in fibrotic areas but deemed non-essential for fibrosis pathogenesis.
Conclusions:
- Massive fibrosis and myocardial disarray are key features in fatal congestive heart failure associated with hypertrophic cardiomyopathy.
- The pattern of fibrosis and inflammation suggests specific regional vulnerabilities within the left ventricle.
- While small artery changes occur, they are likely secondary to, rather than causative of, the extensive myocardial fibrosis.
Abstract:
The heart of seven cases of fatal congestive heart failure with dilated left ventricle, developing in 5 patients with symptomatic hypertrophic cardiomyopathy (HCM) and 2 patients with histologically widespread disarray of both ventricles, was morphologically investigated. These 7 cases showed myocardial widespread disarray and massive fibrosis, the mean percent area of fibrosis was 40.6% and 59.4% at upper and lower levels of left ventricles, respectively. Fibrosis was most extensive in the lateral wall, and followed by anterior, posterior and interventricular walls. The severity of cell infiltration in left ventricle was completely matched to that of fibrosis and was most extensive in subepicardial area followed by middle and subendocardial areas of left ventricle. The intima and medial thickness of intramural small arteries in the fibrotic areas was significantly larger (p less than 0.05) than that of nonfibrotic areas, which suggested that the effect of intramural small artery was not essential for pathogenesis of massive fibrosis.