A 30-year-old man comes to the physician for a pre-employment physical examination. He has no past medical history. He exercises regularly and tries to eat a healthy diet.
The patient's blood pressure is 122/70 mm Hg and pulse is 78/min and regular. The jugular venous pressure is estimated at 5 mm H₂O. There are no carotid bruits. A 3/6 short systolic murmur is heard at the left lower sternal border and the apex in the supine position, and the murmur gets longer with standing. There is a normal splitting of the second heart sound. The apical impulse is not displaced. Femoral pulses are full and symmetric.
Which of the following is the most likely diagnosis?

Question

Quizplus · Accepted Answer

11ec193a_976f_1690_853d_05959a9b1d42_MD0002_00 The presence of a short systolic murmur at the left sternal border and cardiac apex that gets longer with standing is most consistent with mitral valve prolapse (MVP) with mitral regurgitation (MR). Cardiac auscultation in patients with MVP typically shows single or multiple non-ejection clicks (caused by snapping of mitral chordae during systole) and/or mid to late systolic murmur of mitral regurgitation. Standing from a supine position and the Valsalva maneuver decrease the venous return to the heart, decreasing left ventricular (LV) volume and cavity size. This causes a greater degree of prolapse of the mitral valve, making the murmur of MVP more pronounced. Maneuvers that increase LV filling (ie, squatting, leg raise) will improve the closure of the mitral leaflets, delay the click, and soften the murmur. (Choice A) Patients with atrial septal defect (ASD) usually have a wide, fixed splitting of second heart sound. Patients with large left-to-right shunt can develop a mid-systolic or ejection murmur due to increased flow across the pulmonary valve or a diastolic rumble due to increased flow across the tricuspid valve. This patient has normal splitting of the second heart sound, which is not consistent with ASD. (Choice B) Bicuspid aortic valve typically causes a prominent ejection click followed by a mid-systolic murmur, heard best over the right second intercostal space. Bicuspid aortic valve (Choice D) Pulmonic stenosis typically causes an early systolic murmur with maximal intensity at the left upper sternal border. Abrupt standing from a supine position decreases the venous return to the heart and decreases the intensity of the murmur. (Choice E) Tricuspid stenosis causes a mid-diastolic murmur heard best along the left lower sternal border. The murmur increases in intensity with inspiration and/or leg elevation and diminishes in intensity with standing from a supine position due to decrease in the venous return to the right side of the heart. Educational objective: Mitral valve prolapse is associated with single or multiple non-ejection clicks and/or mid to late systolic murmur of mitral regurgitation. Standing or the Valsalva maneuver causes an earlier systolic click and longer murmur (due to decreased venous return and left ventricular volume). Squatting or leg elevation causes a delayed systolic click and shorter murmur (due to increased left ventricular volume). __________ References: Mitral valve prolapse: causes, clinical manifestations, and management. (http://www.ncbi.nlm.nih.gov/pubmed/2667419)

A 30-Year-Old Man Comes to the Physician for a Pre-Employment