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MKSAP 17 Answer & Critique
Answer: A, Aortic regurgitation
Educational Objective: Diagnose severe aortic regurgitation.
Critique: This patient has aortic regurgitation. The murmur of aortic regurgitation, described as a diastolic decrescendo murmur, is heard best at the third left intercostal space and may be better heard when the patient is at end-expiration, leaning forward. Chronic aortic regurgitation has many associated findings, including widened pulse pressure, bounding carotid and peripheral pulses, and a diffuse and laterally displaced point of maximal impulse. A low-pitched rumbling diastolic murmur ("Austin Flint murmur") can accompany aortic regurgitation and is caused by premature closure of the mitral leaflets due to the regurgitant aortic flow.
The auscultatory findings for mitral stenosis include an opening snap with a low-pitched mid-diastolic murmur (often described as a rumble) that accentuates presystole and is heard best at the apex with the patient in the left lateral decubitus position. It most often occurs in patients with rheumatic valve disease and is frequently associated with atrial fibrillation.
A small patent ductus arteriosus in the adult produces an arteriovenous fistula with a continuous murmur that envelops the S2 and is characteristically heard beneath the left clavicle. Patients with a moderate-sized patent ductus arteriosus may present with a continuous "machinery-type" murmur best heard at the left infraclavicular area and bounding pulses with a wide pulse pressure.
The sinuses of Valsalva are three aortic dilatations just above the aortic valve cusps. Two of the three sinuses are the origins of the coronary arteries. Regurgitant blood flow into the sinus structures fills the coronary arteries and assists in the closure of the aortic valve cusps. Sinus of Valsalva aneurysm is a type of aortic root aneurysm. Rupture of the aneurysm will allow flow between the sinus of Valsalva and either the right atrium or right ventricle, producing a continuous systolic and diastolic murmur heard loudest at the second left intercostal space. Clinical presentation can vary, ranging from asymptomatic to decompensated heart failure. Ruptured sinus of Valsalva aneurysm more frequently involves the left or right coronary cusps and less frequently the noncoronary cusp.
Key Point: The murmur of aortic regurgitation is a diastolic decrescendo murmur heard best at the left third intercostal space; associated findings include widened pulse pressure, bounding carotid and peripheral pulses, and a diffuse and laterally displaced point of maximal impulse.
Choudhry NK, Etchells EE. The rational clinical examination. Does this patient have aortic regurgitation? JAMA. 1999;281(23):2231-8. [PMID: 10376577]