What are the characteristic auscultatory findings of a mitral stenosis murmur?

Mitral Stenosis Murmur Characteristics

The mitral stenosis murmur is a low-pitched, rumbling, apical diastolic murmur best heard at the cardiac apex with the bell of the stethoscope, characteristically preceded by an opening snap after the second heart sound. 1

Key Auscultatory Features

Opening Snap

• An opening snap occurs after the second heart sound (S2) and represents the sudden tensing of the stenotic mitral valve leaflets as they open in early diastole 1
• The opening snap is a characteristic finding that helps distinguish mitral stenosis from other causes of diastolic murmurs 1
• The interval between S2 and the opening snap shortens as stenosis severity increases, reflecting higher left atrial pressure 1

Diastolic Murmur Character

• The murmur is middiastolic or presystolic, occurring during ventricular filling when blood flows across the narrowed mitral orifice 1, 2
• It has a low-pitched, rumbling quality that is best appreciated with the bell of the stethoscope placed lightly on the skin 1, 2
• The murmur is loudest at the left ventricular apex and does not radiate significantly 1, 2

Presystolic Accentuation

• In patients with sinus rhythm, the murmur often demonstrates presystolic accentuation—a crescendo just before S1—due to increased flow velocity during atrial contraction 1, 2
• This presystolic component disappears in atrial fibrillation when coordinated atrial contraction is lost 3

Dynamic Auscultation Maneuvers

• Left lateral decubitus position brings the left ventricular apex closer to the chest wall and makes the murmur more audible 2
• Exercise or any maneuver that increases heart rate shortens diastole and increases the transmitral gradient, making the murmur louder 1
• The murmur increases with expiration because it is a left-sided murmur, following the general principle that left-sided murmurs are louder during expiration 2

Associated Findings

• Accentuated (loud) first heart sound (S1) is common in mitral stenosis with pliable leaflets, reflecting forceful closure of the stenotic valve 1
• As stenosis becomes more severe with heavy calcification, S1 may become soft 1
• Pulmonary hypertension may develop in advanced cases, leading to a loud P2 component of the second heart sound 1

Clinical Pitfalls

• The murmur may be inaudible in patients with low cardiac output, obesity, chest wall deformity, or emphysema despite hemodynamically significant stenosis 1
• Patients often present with nonspecific complaints of exertional dyspnea and an unrevealing physical examination, making the diagnosis easy to miss 1
• Atypical high-pitched diastolic murmurs can occur when the mitral orifice has a tadpole-shaped deformity with eccentric flow jets, heard best at the mesoapical area rather than the true apex 4
• Nonobstructive hypertrophic cardiomyopathy can mimic mitral stenosis with a loud S1, opening snap-like sound, and presystolic murmur—echocardiography is essential to differentiate 5

Diagnostic Confirmation

• Transthoracic echocardiography (TTE) is mandatory in all patients with suspected mitral stenosis to confirm the diagnosis, quantify severity (mitral valve area, mean gradient, pulmonary artery pressure), and assess valve morphology 1
• Physical examination findings alone are insufficient to grade severity—echocardiography provides the definitive hemodynamic assessment 1