Valvular Pathology : Mitral Stenosis

Was talking to a bunch of residents who were skeptical that they'd be able to pick up on valvular pathology doing a bedside echo. So here's the first of what will be a few posts on valvular heart disease for the EM and Critical Care physician.

Mitral stenosis usually results from rheumatic carditis (though there are, of course, a number of other causes) and most commonly presents decades later with atrial fibrillation (due to LAE), embolic events (due to afib), hoarseness (compression of recurrent laryngeal due to LAE), or hemoptysis (secondary to pulmonary HTN). TEE is more accurate for estimating gradients and judging severity of disease, but TTE is just fine for making the diagnosis at the point of care.

Hallmarks are left atrial enlargement, thickening and restrictive motion of the mitral valve, and atrial thrombus. On a parasternal long or apical 4 chamber view, a characteristic "elbowing" of the anterior mitral valve leaflet (AMVL) is seen as the valve apparatus opens during diastole but the leaflet's tip is tethered at the valve orifice. Clip below is apical oblique with left side of heart on right side of screen (note the elbowing of the AMVL and the biatrial enlargement in this patient with longstanding mitral stenosis):



A parasternal or subcostal short axis view will demonstrate thickening of both anterior and posterior mitral valve leaflets as seen here:



Also M-mode can demonstrate anterior motion of the posterior mitral valve leaflet during diastole as it is tethered to the AMVL.

Grading severity and estimating mitral valve area is best done using Doppler estimation of the pressure gradient between LV and LA, and while not extremely complicated is beyond the focus of this blog and will not be covered here.