Left ventricular endomyocardial biopsy. II: the value of light microscopy.
Histological sections of left ventricular endomyocardial biopsies have been examined by light microscopy. The biopsies were taken from patients with congestive, hypertrophic, or restrictive cardiomyopathy and from patients with either aortic stenosis or regurgitation. In congestive cardiomyopathy no specific features were found and similar abnormalities were seen in aortic valve disease. In only one of six cases of asymmetric septal hypertrophy were the characteristic histological appearances noted. In four out of five patients with a restrictive type of cardiomyopathy, amyloid was demonstrated. The muscle fibres in aortic stenosis had a greater cross-sectional area than those in aortic regurgitation. A greater degree of fibrosis was present in aortic stenosis than in aortic regurgitation. In aortic stenosis the amount of fibrous tissue was inversely related to function.