|a u s c u l t a t i o n t u t o r
Mitral Stenosis & opening snap
The auscultatory findings characteristic of mitral stenosis are a loud first
heart sound, an opening snap, and a diastolic rumble. The first heart
sound is accentuated because of a wide closing excursion of the mitral
leaflets. The degree of loudness of the first heart sound depends on the
pliability of the mitral valve. The intensity of the first heart sound
diminishes as the valve becomes more fibrotic, calcified, and thickened.
The second heart sound is normally split, and the pulmonic component
is accentuated if pulmonary hypertension is present. The opening snap
follows the second heart sound. The sudden tensing of the valve leaflets
after they have completed their opening excursion causes an opening
snap. In patients with elevated left atrial pressure and hence with severe
mitral stenosis, the opening snap occurs closer to the second heart sound.
The diastolic murmur of mitral stenosis is of low pitch, rumbling in
character, and best heard at the apex with the patient in the left lateral
position. It commences after the opening snap of the mitral valve, and
the duration of the murmur correlates with the severity of the stenosis.
The murmur is accentuated by exercise, whereas it decreases with rest
and Valsalva maneuver. In patients with sinus rhythm, the murmur
increases in intensity during late diastole (so called, presystolic
accentuation) due to increased flow across the stenotic mitral valve
caused by atrial contraction.
A high-pitched decrescendo diastolic murmur secondary to pulmonary
regurgitation (Graham Steell murmur) may be audible at the upper
A pansystolic murmur of TR and an S 3 originating from the right
ventricle may be audible in the 4th left intercostal space in the patient
with right ventricular dilatation.Stenosis of the mitral valve typically
occurs decades after the episode of acute rheumatic carditis.
Acute insult leads to formation of multiple inflammatory foci (Aschoff
bodies, perivascular mononuclear infiltrate) in the endocardium and
myocardium. Small vegetations along the border of the valves may also
be observed. With time, the valve apparatus becomes thickened,
calcified, and contracted, and commissural adhesion occurs, ultimately
resulting in stenosis.
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