Familial hypertrophic cardiomyopathy is a disease of heart muscle that is genetically transmitted as an autosomal dominant trait, with a high degree of penetrance. Affected individuals typically have asymmetric thickening of the interventricular septum often involving the adjacent left ventricular free wall. Histologically, myocardial cells are enlarged and muscle bundles are grossly disorganized, producing a whorled pattern. The physiologic consequence of this cardiomyopathy is diastolic dysfunction with impaired ventricular relaxation and elevated diastolic pressures in the heart and pulmonary vasculature. Patients can experience dyspnea, angina, palpitations, and syncope. Complications of the disease include atrial fibrillation, congestive heart failure, thromboembolism, and most importantly, sudden death.