Author Affiliation: Section of Clinical Electrophysiology and Inherited Cardiac Diseases, Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md.
Grand Rounds at the Clinical Center of the
National Institutes of Health Section Editors: John I. Gallin, MD, the Clinical Center
of the National Institutes of Health, Bethesda, Md; David S. Cooper,
MD, Contributing Editor, JAMA.
A 28-year-old woman was diagnosed as having obstructive
hypertrophic cardiomyopathy (HCM) during a family screening 13 years
ago. The patient was initially treated with atenolol and verapamil for
chest pain, but after several years, she complained of increasing
angina and dyspnea. Physical examination revealed a prominent apical
impulse and a grade 2/6 precordial systolic murmur. The 12-lead
electrocardiogram showed sinus rhythm at 79/min, PR interval of 205
milliseconds, normal QRS axis, and left ventricular (LV)
hypertrophy plus associated ST-T wave changes. The echocardiogram
showed a septal thickness of 19 mm (normal, ≤11 mm); LV free wall, 15
mm (normal, <11 mm); left atrium, 52 mm (normal, <40 mm); no
systolic anterior motion of the mitral valve, but apposition of LV
walls at the level of papillary muscles; mild mitral regurgitation; and
predicted LV gradient of 85 mm Hg at rest. A cardiac magnetic resonance
imaging study confirmed LV hypertrophy, most marked at the mid-LV
cavity level, and an apical LV aneurysm. The pressures at cardiac
catheterization were as follows: mean right atrium, 4 mm Hg; right
ventricle, 36/4 mm Hg; pulmonary artery, 30/14 mm Hg; mean pulmonary
arterial capillary wedge , 19 mm Hg; LV, 190/20 mm Hg; and aorta,
100/50 mm Hg. Hence, the intracavitary LV pressure gradient, measured
at midcavity, was 90 mm Hg. Cardiac output was 4.7 L/min. An LV
angiogram confirmed a diagnosis of midcavity obstructive HCM. Genetic
studies showed that HCM in the patient's family is caused by an
Met149Val mutation of a cardiac contractile protein called essential
light chain of myosin.
Fananapazir L. Advances in Molecular Genetics and Management of Hypertrophic Cardiomyopathy. JAMA. 1999;281(18):1746–1752. doi:10.1001/jama.281.18.1746
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