PLAX view in MS

PLAX view in MSPLAX view in MS

Echocardiogram in parasternal long axis view in mitral stenosis. The anterior mitral leaflet is seen to be domed, with a hockey stick appearance. The posterior mitral leaflet moves anteriorly instead of the normal posterior movement (paradoxical motion). Both these abnormalities are a consequence of commissural fusion in rheumatic mitral stenosis. Left atrium is dilated as a sequelae of mitral stenosis or associated mitral regurgitation which can only be documented by Doppler (either color Doppler or continuous wave Doppler).

Fair diastolic separation of the tips of mitral leaflets indicate that the mitral stenosis is unlikely to be severe. Hence the left atrial dilatation is likely to be due to significant mitral regurgitation. Another possibility is that mitral valve opening could have increased after a procedure like balloon mitral valvotomy, but pre existing left atrial dilatation has not regressed. Atrial fibrillation often associated with mitral stenosis is another potential reason for left atrial enlargement. Atrial fibrillation is more often related to duration of mitral stenosis than its severity.

Mitral valve area can be measured by planimetry in a cross sectional image or by pressure half time in Doppler echo. Other less often used methods are using continuity equation and proximal isovelocity surface area method. Another mitral leaflet separation index has been introduced as a surrogate measure of mitral valve area [1]. MLS index was estimated by the maximal separation of mitral leaflet tips at end diastole. It was measured in PLAX view and apical 4 chamber view. Three measurements were made in each view and the mean was taken as MLS index. In patients with atrial fibrillation, five measurements were taken in each view and mean obtained. There was good correlation between MLS and MVA by planimetry.

Reference

  1. Thomas JK, Anoop TM, Sebastian GB, George K, George R. Mitral leaflet separation index in assessing the severity of mitral stenosis. ISRN Cardiol. 2011;2011:768097.