Left panel shows the parasternal long axis view (PLAX). AO: Aorta; MVO: Mitral valve opening; LA: left atrium. Doming of the anterior mitral leaflet is seen well and has the appearance of hockey stick. Left atrium is dilated.
Right panel shows parasternal short axis view (PSAX). LV: Left ventricle; MVO: Mitral valve orifice. The mitral orifice is seen within the cross section of the left ventricle. The anterior and posterior leaflets are seen in cross section and are thickened; the commissures are fused. Commissural fusion causes the doming of the anterior mitral leaflet seen in the PLAX view as well as the anterior (paradoxical) movement of posterior leaflet in diastole in mitral stenosis. Normally the posterior leaflet moves posteriorly in diastole.
Parasternal long axis view will give an assessment of the subvalvar apparatus. Subvalvar fusion may result in poor results after valvotomy as they can produce secondary obstruction beyond the valve. Parasternal short axis view is used for quantitating the severity of mitral stenosis by using planimetry to measure the mitral valve orifice. Commissural fusion and calcification if present can be seen well on PSAX view. Trans mitral gradient is better assessed in apical four chamber view by Doppler. Associated tricuspid regurgitation (TR) if present, can be seen on apical four chamber view, which will also helps in estimating the right ventricular systolic pressure from the TR gradient.