Congenital heart disease associated with hypertrophic cardiomyopathy.

Experience has shown that clinical hypertrophic cardiomyopathy (HOCM, ASH) occurs in some patients with congenital heart disease, particularly simple lesions with a good natural prognosis. Its presence should be suspected when the clinical course is atypical for the basic congenital lesion or when there is unexpected cardiomegaly, an associated left sided lesion or left ventricular hypertrophy in abnormalities which primarily affect the right side of the heart, or an atypical electrocardiogram showing QS patterns, left anterior hemiblock, deeply inverted septal T inversion, or unusual ST-T changes over the left ventricle. Histopathologically, 'myocardial dysplasia', indistinguishable on light microscopy from HOCM, is common in many hearts with congenital cardiac lesions, particularly in the ventricular septum. It varies in extent, distribution, and site. Its presence may account for certain unpredictable changes in congenital heart disease. The influence of 'dysplasia' on the clinical state in both isolated myopathy and when combined with congenital heart lesions depends on its extent and on the occurrence of secondary postnatal haemodynamic and biochemical disturbances. Myocardial dysplasia is probably congenital and common and it may be asymptomatic; pathologist and clinician should be aware of and search for it.