OSH Echocardiography 2e
4. Transthoracic anatomy and pathology: chambers and vessels
Diastolic function
Diastolic function: tips and measures
Transmitral flow categorization (see Figs. 4.16 and 4.31)
- Impaired relaxation
This is characterized by reduction of the peak transmitral pressure gradient (hence lower E velocity and E/A ratio [<1 in young, <0.5 in elderly]) and prolongation of the E deceleration slope (>220ms in young, >280ms in elderly). Cardiac pacing, left bundle branch block, and RV overload may provoke the same changes.
- Pseudonormal filling
As left atrial pressure increases with progressive left ventricle disease, E velocity and deceleration time return to normal. With exception of patients with more marked elevations of filling pressure and low heart rate, who may show a mid-diastolic (‘L’) wave, transmitral flow patterns cannot be distinguished from normal without the performance of other steps. The first step is to suspect the condition—‘normal’ transmitral flow in the setting of left ventricle enlargement, hypertrophy, or systolic dysfunction is likely to be pseudonormal. The second step is to assess left atrial size, followed by estimation of filling pressure (as E/E’) and tissue Doppler of the mitral annulus. Note that when left ventricle ejection fraction is preserved, E deceleration time, the Valsalva response, blunting of the pulmonary venous S wave (and S/D ratio), and flow propagation velocity may be unreliable indicators of diastolic dysfunction.
- Restrictive filling
Continued elevation of filling pressure leads to increased E velocity (increase in E/A ratio >2) and shorter E deceleration time (<150ms). This finding is unusual with normal ejection fraction (indicating a restrictive cardiomyopathy, e.g. amyloidosis), and is more commonly associated with left ventricle dilatation and severe systolic dysfunction. The presence of reversibility (i.e. normalization with Valsalva or after diuresis) is prognostically very important.