A 52-year-old man comes to the physician because of a 2-month history of palpitations. He says that he can feel his heartbeat in his chest all the time. For the past 3 weeks, he has had shortness of breath on exertion. He has not had chest pain, orthopnea, or nocturnal dyspnea. He has a history of intravenous drug use and diagnosed with infective endocarditis which was successfully treated with a long course of antibiotics. He emigrated from Nepal at the age of 25 years. His temperature is 36.5°C (97.7°F), pulse is 103/min, and blood pressure is 145/56 mm Hg. Chest auscultation reveals a decrescendo diastolic murmur over the third intercostal space along the left sternal border. Echocardiogram shows severe aortic regurgitation, likely as a sequela to the prior infection. Which of the following changes is most responsible for maintaining cardiac output in the setting of this valvular abnormality?

Question

A 52-year-old man comes to the physician because of a 2-month history of palpitations. He says that he can feel his heartbeat in his chest all the time. For the past 3 weeks, he has had shortness of breath on exertion. He has not had chest pain, orthopnea, or nocturnal dyspnea. He has a history of intravenous drug use and diagnosed with infective endocarditis which was successfully treated with a long course of antibiotics. He emigrated from Nepal at the age of 25 years. His temperature is 36.5°C (97.7°F), pulse is 103/min, and blood pressure is 145/56 mm Hg. Chest auscultation reveals a decrescendo diastolic murmur over the third intercostal space along the left sternal border.  Echocardiogram shows severe aortic regurgitation, likely as a sequela to the prior infection.  Which of the following changes is most responsible for maintaining cardiac output in the setting of this valvular abnormality?

Quizplus · Accepted Answer

Eductional Objective: In chronic aortic regurgitation, persistent left ventricular volume overload triggers eccentric hypertrophy, which causes a compensatory increase in stroke volume to maintain cardiac output.  This compensatory mechanism allows for a relatively long asymptomatic period in most patients; however, left ventricular dysfunction eventually occurs, leading to heart failure.

A 52-Year-Old Man Comes to the Physician Because of a 2-Month