Transmitral Doppler indices
Key variables to be considered during echocardiographic evaluation of
diastolic dysfunction include early diastolic transmitral velocity (E),
early diastolic mitral annular velocity by tissue Doppler imaging (TDI)
(eā) and their corresponding relationship (E/eā), LA volume index (LAVi)
and peak tricuspid regurgitation velocity.40 In the
setting of MS, however, these offer limited value to assess myocardial
disease as they are often related to the degree of valvular stenosis.
E-wave velocity reflects left-sided atrioventricular gradient during
early diastole and is affected by alterations in LV relaxation and LA
pressure. In the setting of significant LV diastolic dysfunction,
transmitral gradient is low despite increased LA pressure owing to
concomitant increase in LV diastolic pressure. Pressure half-time
employing echocardiography, thereby, is decreased due to increase in LV
diastolic pressure caused by increased LV chamber stiffness and hence,
may not provide an accurate estimation of valve area using this
method.40 (Figures ā 1, 2). Further, elevated
transmitral velocities secondary to valvular obstruction and lower
myocardial velocities in the setting of reduced output result in
abnormally high E/eā values that may not faithfully represent invasive
filling pressures.41 LA volumes are often increased as
an adaptation response to elevated pressures secondary to valvular
obstruction. This is further compounded by the frequent occurrence of
AF, which further distorts LA geometry. In keeping with these
observations, current guidelines have suggested that recommended
echocardiographic measures to identify LV diastolic function may not be
accurate to assess LV filling pressures in the setting of significant
mitral valve disease.40