A 22-year-old man comes to the clinic for a routine physical. The patient has no medical problems and takes no medication. He does not use tobacco, alcohol, or illicit drugs. He plays on his college football team and participates in intense training sessions and weekly games. Review of systems is unremarkable. Blood pressure is 120/76 mm Hg, pulse is 68/min, and respirations are 15/min. BMI is 28 kg/m². Blood pressures in the upper and lower extremities are equal. There is no jugular venous distension. Carotid upstrokes are brisk. There is a grade 2/6 early systolic murmur along the left sternal border. The murmur decreases in intensity with hand grip and passive leg elevation. Lung sounds are normal without crackles or wheezes. Echocardiogram is most likely to demonstrate which of the following findings?

Question

Quizplus · Accepted Answer

This patient with a systolic murmur along the left sternal border that decreases in intensity with maneuvers that increase left ventricular (LV) blood volume likely has hypertrophic cardiomyopathy (HCM). HCM typically involves hypertrophy of the interventricular septum that can partially obstruct LV outflow and cause a murmur. Increases in LV blood volume, caused by maneuvers that increase preload (eg, passive leg elevation) or increase afterload (eg, handgrip), alleviate the LV outflow obstruction of HCM and decrease the intensity of the murmur. HCM is characterized by increased LV muscle mass and a small LV cavity. Because LV contractility is typically intact and outflow obstruction is dynamic and commonly only present with exercise, there is usually preserved ejection fraction. However, impaired relaxation of the hypertrophied LV wall typically leads to diastolic dysfunction. (Choices A and E) Increased LV mass with a dilated LV cavity, decreased LV ejection fraction, and normal LV relaxation are consistent with dilated cardiomyopathy. Normal LV mass and cavity size with preserved ejection fraction and impaired LV relaxation describe restrictive cardiomyopathy; the LV walls are stiffened but are not typically thickened. Both conditions are likely to lead to symptomatic heart failure with jugular venous distension and pulmonary edema (evidenced by crackles on lung auscultation). (Choice B) Increased LV mass with normal LV relaxation and normal (or somewhat increased) LV cavity size and ejection fraction are consistent with athlete's heart, which describes physiologic cardiac changes (eg, LV cavity enlargement and wall thickening) that improve cardiac function in response to intense endurance training. A murmur consistent with HCM is not expected in athlete's heart. (Choice C) Increased LV mass with small LV cavity size, decreased ejection fraction, and impaired ventricular relaxation occurs in severe aortic stenosis. The fixed obstruction created by the stenotic valve leads to pressure overload and concentric LV hypertrophy, and also restricts stroke volume to decrease ejection fraction. The murmur of aortic stenosis is similar to that of HCM but is differentiated by a decrease in intensity with maneuvers that decrease (rather than increase) LV preload (eg, abrupt standing, Valsalva strain phase). Educational objective: Hypertrophic cardiomyopathy (HCM) typically involves interventricular septal hypertrophy that obstructs left ventricular (LV) outflow and creates a systolic murmur that decreases in intensity with maneuvers that increase LV blood volume (eg, hand grip, passive leg elevation). HCM is characterized by increased LV muscle mass with a small LV cavity, preserved ejection fraction, and impaired LV relaxation leading to diastolic dysfunction.

A 22-Year-Old Man Comes to the Clinic for a Routine