Hypertrophic Cardiomyopathy

This photomicrograph is from the septum in a case of hypertrophic obstructive CM. Note myofiber disarray with bundles running in all directions. Interstitial fibrosis is also present. Unfortunately, disarray is not pathognomic of HCM.

Hypertrophic cardiomyopathy (HCM) is a relatively rare but deadly syndrome. It can result in sudden death, especially in younger patients. Sudden death is not always preceded by earlier symptoms. The disease has a genetic basis with defects in the genes encoding various sarcomeric proteins. The hallmark is inappropriate myocardial hypertrophy. IHCM can be obstructive or nonobstructive. When left ventricular tract outflow tract obstruction occurs, it is related to asymmetric septal hypertrophy and to anterior systolic motion of the anterior leaflet of the mitral valve. There is also impaired left ventricular filling due to diastolic dysfunction. Hypertrophic cardiomyopathy with similar pathological findings can be seen in the infant of a diabetic mother, in which case it is transient if the infant survives.