Hypertrophic Cardiomyopathy

Background: genetic disorder; autosomal dominant inheritance (variable penetrance & expressivity) Variable presentations High-risk of sudden death -- leading cause of sudden cardiac death in adolescent & pre-adolescent individuals Major disorder characteristic: asymmetric, myocardial hypertrophy without hypertrophic stimulus most commonly involves interventricular septum  promoting flow obstruction through the left ventricular (LV) outflow tract Pathophysiology: Significant pressure gradient across the LV outflow tract Probably due to additional narrowing of already small outflow tract, due to ventricular hypertrophy (septal) and possible mitral valve abnormal location Associated with increased ejection velocity secondary to abnormal left ventricular tract orientation/geometry: important predisposing factor in endocarditis Abnormal diastolic function associated with impaired ventricular filling & filling pressure Patients have abnormal calcium kinetics and subendocardial ischemia Molecular Basis Gene defects associated with sarcomeric protein encoding myosin heavy chain actin tropomyosin

courtesy of e- medicine, http://www.emedicine.com/ped/topic1102.htm, used with permission Topic: cardiomyopathy, hypertrophic Authors: Berus, C., Director, Pacemaker Services, Assistant Professor of Pediatrics, Department of Cardiology, Harvard Medical School, Boston Children's Hospital and Zevitz, M.E., Assistant Professor, Department of Medicine, Finch  University of Health Sciences, Veterans Affairs Medical Center