MEDizzy - Mr. Abraham is a 62-year-old former sea urchin collector

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Cardinal Manifestations and Presentation of Diseases 2

Mr. Abraham is a 62-year-old former sea urchin collector with a history of right total knee replacement 10 years ago and prior tobacco abuse. He presents to your ofce complaining of chest pain with moderate exertion and some mild dyspnea with walking up hills. On examination, you note a mid-systolic murmur. After careful listening, you are unsure whether this is the murmur of aortic stenosis or of the obstructive form of hypertrophic cardiomyopathy. Which maneuver is appropriately matched to the clinical fnding that would suggest that this murmur is due to obstructive hypertrophic cardiomyopathy as opposed to aortic valvular stenosis?

ExplanationThe obstructive form of hypertrophic cardiomyopathy (HOCM) is associated with a midsystolic murmur that is usually loudest along the left sternal border or between the left lower sternal border and the apex. The murmur is produced by both dynamic left ventricular outfow tract obstruction and MR, and thus, its confguration is a hybrid between ejection and regurgitant phenomena. The intensity of the murmur may vary from beat to beat and after provocative maneuvers but usually does not exceed grade 3. The murmur classically will increase in intensity with maneuvers that result in increasing degrees of outfow tract obstruction, such as a reduction in preload or afterload (Valsalva, standing, vasodilators) or with an augmentation of contractility (inotropic stimulation such as milrinone). However, augmentation of contractility will also increase the intensity of the murmur of aortic stenosis and thus is not useful for diferentiation. Augmentation of afterload (hand grip) is associated with diminished murmur intensity in both aortic stenosis and obstructive hypertrophic cardiomyopathy. Maneuvers that increase preload (squatting, passive leg raising, volume administration) or afterload (squatting, vasopressors) or agents that reduce contractility (β- adrenoceptor blockers) decrease the intensity of the murmur of hypertrophic cardiomyopathy. In contrast to AS, the carotid upstroke is rapid and of normal volume. Rarely, it is bisferiens or bifd in contour due to midsystolic closure of the aortic valve.