USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Which heart anomaly results in a midsystolic "click" on auscultation?

1. Coarctation of the aorta

2. Patent ductus arteriosus

3. Mitral stenosis

4. Systolic heart failure

The correct answer is: Systolic heart failure

The presence of a midsystolic "click" during auscultation is most commonly associated with mitral valve prolapse, which is seen in mitral stenosis as a secondary phenomenon. In mitral valve prolapse, the chordae tendineae are elongated or the valve leaflets are redundant, leading to a situation where the leaflets billow back into the left atrium during systole. This can produce the characteristic click sound, which occurs just after the first heart sound (S1) and before the second heart sound (S2). The other conditions listed do not typically present with a midsystolic click. Coarctation of the aorta and patent ductus arteriosus produce their own characteristic heart sounds and murmurs but lack this specific click. Systolic heart failure is a state of impaired myocardial contractility and is associated with signs and symptoms related to heart failure rather than the presence of a distinct auscultatory finding like a midsystolic click. Thus, mitral stenosis is the anomaly linked to this specific auscultatory finding, highlighting the importance of recognizing characteristic sounds in cardiac examination.