MEDizzy - You are examining a new patient in clinic. On cardiac

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Cardiovascular medicine

You are examining a new patient in clinic. On cardiac auscultation you palpate a double apical impulse. There is a III/VI harsh crescendo “diamond-shaped” murmur that begins well after the first heart sound.The murmur is best heard at the lower left sternal border as well as at the apex. The murmur does not radiate to the neck. There is no respiratory variation. S1 and S2 are normal. With passive elevation of the legs, the murmur decreases in intensity. During the strain phase of the Valsalva maneuver, the murmur increases in intensity.With inhalation of amyl nitrate, the murmur increases in intensity. What is the etiology of this patient’s murmur?

ExplanationThis patient’s murmur is due to hypertrophic cardiomyopathy (HCM). A normal S2, the location of the murmur, the absence of radiation to the neck, and being loudest at the lower left sternal border make aortic sclerosis or aortic stenosis less likely.These murmurs are usually heard best in the second right intercostal space. Maneuvers such as going from standing to squatting and passively raising the legs decrease the gradient across the outflow tract and intensity of the murmur due to increased preload. Amyl nitrate causes a decrease in systemic vascular resistance and arterial pressure. The murmur of HCM increases in intensity while there is less regurgitation across the mitral valve and the murmur of mitral regurgitation gets softer. Right-sided murmurs, except for the pulmonic ejection “click” of pulmonary stenosis, usually increase in intensity during inspiration.