A 45-year-old woman who recently immigrated to the United States is hospitalized with exertional dyspnea and fatigue. She has no significant past medical history and takes no medications. The patient's blood pressure is 110/80 mm Hg and heart rate is 90/min and regular. After cardiopulmonary examination, the physician suspects mitral stenosis. Which of the following is the most useful measure for assessing the degree of mitral stenosis?

Question

A 45-year-old woman who recently immigrated to the United States is hospitalized with exertional dyspnea and fatigue.  She has no significant past medical history and takes no medications.  The patient's blood pressure is 110/80 mm Hg and heart rate is 90/min and regular.  After cardiopulmonary examination, the physician suspects mitral stenosis.  Which of the following is the most useful measure for assessing the degree of mitral stenosis?

Quizplus · Accepted Answer

11ec160b_3a93_aae1_9249_d11aa01106ad_MD0001_00 11ec160b_3a93_aae2_9249_67199e4314e0_MD0001_00 On auscultation, the best indicator of mitral stenosis (MS) severity is the length of time between S2 (specifically the A2 component, caused by aortic valve closure) and the opening snap (OS). The OS occurs due to abrupt tensing of the valve leaflets as the mitral valve reaches its maximum diameter during forceful opening. As MS worsens, left atrial pressures increase due to impaired movement of blood into the left ventricle. Higher pressure causes the valve to open more forcefully; as a result, the A2-OS interval becomes shorter as left atrial pressure increases. The current standard for diagnosis and determination of MS severity is measurement of mean transvalvular pressure gradients via 2-D Doppler echocardiography. (Choices B and C) Left-sided S3 and/or S4 gallops are generally absent in MS, since left ventricular filling is normal or decreased. When MS is severe enough to produce pulmonary hypertension, patients may develop right-sided heart failure. As a result, a right-sided S3 and/or S4 can occur. However, these right-sided gallops arise only in severe, end-stage MS and are not useful for differentiating between mild and moderate MS. (Choice D) Diastolic rumble intensity in MS does not correlate well with stenosis severity. This is due to murmur intensity being dependent on both the transvalvular pressure gradient and the amount of blood flowing through the valve. In very severe stenosis, the diastolic murmur may be completely absent due to greatly reduced flow across the valve. (Choice E) Presystolic accentuation of the MS murmur occurs due to increased transvalvular flow associated with left atrial contraction. This accentuation is heard across a wide range of MS severity. More significant than the degree of presystolic accentuation is its presence or absence. When MS becomes severe enough to precipitate atrial fibrillation, presystolic accentuation of the MS murmur disappears. Educational objective: The best and most reliable auscultatory indicator of the degree of mitral stenosis is the A2-OS interval. A shorter interval indicates more severe stenosis. Other auscultatory findings can include a diastolic rumbling murmur with presystolic accentuation due to left-atrial contraction.

A 45-Year-Old Woman Who Recently Immigrated to the United States