Echocardiography Exam 2 Practice Test

Estimating LV filling pressures is best done with the E/e′ ratio when the E/A pattern isn’t helping. Here, E is the early diastolic transmitral flow velocity and e′ is the early diastolic velocity of the mitral annulus measured by tissue Doppler. As left heart filling pressures rise, the early transmitral velocity (E) tends to increase while the myocardial relaxation velocity (e′) doesn’t rise as much, so the ratio E/e′ increases. This makes E/e′ a useful proxy for LV filling pressures, especially in cases where the E/A ratio is nondiagnostic due to pseudonormalization or other loading effects.

Using the average of the septal and lateral e′ velocities improves accuracy because it accounts for regional variations in relaxation. A commonly used threshold is an average E/e′ of 14 or greater, which suggests elevated LV filling pressures (often LVEDP > 15 mmHg).

S′ velocity reflects systolic function rather than filling pressures, and deceleration time and E/A alone can be misleading in certain diastolic states, making E/e′ the more reliable indicator in this scenario.