Diastolic function assessment by echo in AF
Diastolic function assessment by echo in the AF: Conventionally left ventricular diastolic function assessment by echocardiography relies on mitral inflow velocity measurement with demonstration of E/A reversal as an evidence of diastolic dysfunction. In atrial fibrillation, the absence of atrial contraction and the A wave makes this conventional assessment impossible. Moreover, the variation in the cardiac cycle also causes beat to beat changes in ventricular relaxation. A variety of other parameters have been reported to be useful in assessing diastolic function and left ventricular filling pressures by echocardiography in the presence of atrial fibrillation. They include mitral E wave deceleration time, ratio of mitral E wave to tissue Doppler derived mitral annular e’, color M-mode derived Vp (early diastolic flow propagation velocity) and the ratio of mitral E wave to Vp, peak pulmonary vein diastolic flow velocity, pulmonary vein diastolic wave deceleration time, peak acceleration of the mitral E wave, isovolumetric relaxation time and the ratio of isovolumetric relaxation time to the time between the onsets of mitral E wave and the mitral annular e’ wave.
Flow propagation velocity (Vp) on colour M-Mode, is measured as the slope of the first color aliasing velocity from the mitral annulus in early diastole to 4 centimeters distally into the left ventricular cavity [1].
A dual Doppler technique has been described recently, for simultaneous measurement of E and e’ so that the ratio E/e’ can be calculated in the same beat itself. This avoids the beat to beat variation in these values which would compound a non simultaneous measurement. Short of this novel technique, any measurement in atrial fibrillation would need averaging of values for five to ten cardiac cycles. Mitral diastolic E wave deceleration time of less than 100 milliseconds correlates with a pulmonary wedge pressure of more than 18 mm Hg. Deceleration time is the duration between the peak of the E wave and the upper deceleration slope extrapolated to the baseline. It is usually measured from the apical four chamber view. Pulmonary vein diastolic wave deceleration time is also measured in a similar way from the right upper pulmonary vein in the apical four chamber view.
Reference
- J E Møller, E Søndergaard, J B Seward, C P Appleton, K Egstrup. Ratio of left ventricular peak E-wave velocity to flow propagation velocity assessed by color M-mode Doppler echocardiography in first myocardial infarction: prognostic and clinical implications. J Am Coll Cardiol. 2000 Feb;35(2):363-70.