Adult Echocardiography Practice Exam

Higher than normal heart rates may cause the Doppler signal of the left ventricular inflow to:

1. have a high A velocity

2. have a low E velocity

3. have no effect on the E/A velocity

4. have a single E/A velocity

The correct answer is: have a single E/A velocity

Higher than normal heart rates can significantly affect the Doppler signal of the left ventricular inflow, leading to the phenomenon known as "pseudo-normalization." At elevated heart rates, the filling dynamics of the ventricle change, which can alter the typical patterns observed in the E/A ratio, where E represents the early diastolic flow and A represents the atrial contraction flow. When heart rates are high, the diastolic filling time is shortened. As a result, the reliance on the E wave for early diastolic filling predominates, and with the reduced time available for the ventricle to fill, there may not be sufficient time for the A wave to effectively contribute to the overall inflow pattern. This can result in the signal appearing more like a single wave because the A wave may be diminished or even obscured by rapid ventricular filling dynamics. Consequently, rather than showing a clear distinction between E and A waves, the inflow pattern may present a more homogeneous signal that reflects a single dominant inflow velocity. This is why the Doppler signal can be interpreted as having a single E/A velocity at elevated heart rates, as the filling pattern merges, making it appear more uniform.