Rosh Internal Medicine Boost Practice Exam

A patient presents with a late systolic murmur best heard in the midclavicular line. What cardiac process does this indicate?

1. Left-to-right blood flow across a small ventricular septal defect

2. Regurgitant blood flow from the left ventricle to the left atrium

3. Regurgitant blood flow from the right ventricle to the right atrium

4. Turbulent blood flow across redundant mitral valve tissue

The correct answer is: Turbulent blood flow across redundant mitral valve tissue

A late systolic murmur best heard in the midclavicular line is characteristically associated with mitral valve prolapse, which often produces a murmur due to the abnormal movement of the mitral valve leaflets. In this scenario, the redundancy of the mitral valve tissue can lead to turbulence during systole as the leaflets do not close effectively, which creates a late-systolic murmur as the ventricle contracts. This murmur is typically preceded by a preceding systolic click, which is indicative of the chordae tendineae suddenly tensing as the valve leaflets prolapse into the left atrium. The location of the murmur being best heard at the midclavicular line aligns with the anatomical position of the mitral valve. Understanding this context is crucial because other choices do not fit the characteristics of the murmur described. For example, left-to-right shunting across a small ventricular septal defect would typically present with a holosystolic murmur, not a late systolic one. Similarly, regurgitant flow scenarios from the left ventricle to the left atrium or from the right ventricle to the right atrium usually produce different sound characteristics, positioning them outside of the