Mitral stenosis (MS)
occurring, on average, 20 years before presentation of mitral stenosis.
between the LA and LV, resulting in an icreased left atrial (LA) pressure. Hemodynamic changes (a rise in transvalvular pressure gradient) begin when the cross-sectional area of the valve, is reduced to less than 2 cm2.
Auscultatory findings in MS
The opening snap is an early diastolic sound of short duration, and it is considered as the most characteristic auscultatory finding of mitral stenosis (MS). You can hear the opening snap near the cardiac apex, but it is more easily heard along the lower left sternal border. However, as the disease progresses and the valve becomes more calcified and immobile, the opening snap may be lost. Also the first heart sound (S1), which is usually accentuated (loud) in MS, for the same reason can become softer at a later stage of the disease. The murmur of MS is a low-pitched rumbling mid-diastolic murmur. It is best heard with the bell of the stethoscope with the patient in the left lateral decubitus position. Presystolic accentuation of the murmur can be present if the patient is in sinus rhythm. Auscultation after a brief period of exercise usually accentuates the murmur of MS, because exercise increases the transvalvular gradient, due to the increased cardiac output and heart rate.
The length of the murmur correlates better with the severity of MS than the loudness. MS is more severe when the murmur is longer and when the time interval from the second heart sound (S2) to the opening snap is short.
The electrocardiogram (ECG) in MS, if the rhythm is sinus, shows left atrial enlargement. Atrial fibrillation may be present (it is common in MS). If pulmonary hypertension has developed, then there is also ECG evidence of right ventricular hypertrophy.
Echocardiography in MS
It shows structural abnormalities of the valve (in rheumatic MS mitral leaflets are thickened with abnormal fusion of their commissures). Echocardiography also shows restricted separation
Left atrial enlargement is also present.
The mitral valve area (MVA) can be measured directly from the parasternal short axis view at the level of the tips of the mitral valve. Optimal positioning of the echocardiographic view, in order to obtain this measurement, is done by first obtaining a parasternal long-axis view and placing the mitral valve orifice in the center of the scan plane. The transducer is then rotated 90° to obtain the short-axis view. Measurements are obtained at the tips of the mitral leaflets. Three-dimensional echocardiography can provide a more accurate determination of the mitral valve area (MVA).
MVA can also be calculated from Doppler velocity measurements (the diastolic pressure half time). The pressure half time (PHT) is the time it takes for the pressure gradient across the valve to fall to one-half the starting value. (This is equal to the time for the velocity of the mitral E wave to decrease to 70% of peak velocity). The mitral inflow E wave is used in this calculation.
MVA (in cm2) = 220/PHT.
Current guidelines define clinically important, severe, MS as a valve area ≤1.5cm2 , because this valve area is typically accompanied by left atrial enlargement and elevated pulmonary artery systolic pressure. A valve area ≤1.0 cm2 is termed "very severe" MS.
Severe MS : mean gradient > 10 mm Hg.
Symptoms due to vascular congestion can be improved by restriction of salt intake and diuretic therapy.
Heart rate slowing agents, such as beta-blockers or nondihydropyridine calcium channel blockers (diltiazem or verapamil), increase diastolic left ventricular filling time and so they there decrease symptoms with exercise. These drugs, or digoxin, are also used to slow the ventricular rate in patients with rapid atrial brillation. Anticoagulant therapy to prevent thromboembolism is indicated in MS patients with atrial fibrillation, or an identied LA thrombus, or a prior embolic event.
Percutaneous or surgical valve interventions are the only treatments that alter the natural history of severe MS. They are indicated in patients with severe (see above for the echocardiographic criteria of MS severity), symptomatic MS. Percutaneous mitral balloon
valvuloplasty is the treatment of choice in appropriately selected patients (those without advanced anatomic deformity of the valve, and without moderate or severe mitral regurgitation, or left atrial thrombus). Transesophageal echocardiography (TEE) is indicated to exclude LA thrombus prior to valvuloplasty.
Percutaneous mitral valvuloplasty (PMV) is also indicated for asymptomatic patients with severe MS (valve area ≤1.5cm2) , who have pulmonary hypertension (pulmonary artery systolic pressure > 50 mm Hg at rest or > 60 mm Hg with exercise) if valve morphology is favorable for PMV, in the absence of left atrial thrombus or moderate to severe mitral regurgitation.
Mitral stenosis and echocardiography. A good video by 123sonography