Case 20 — Doppler Echocardiograms

Pulsed wave Doppler tracing with cursor immediately distal to the mitral valve. Flow is toward the transducer (above the line) in diastole. Peak early diastolic velocity is 1.75 m/s (PG ~12 mmHg). A peak of 2 m/s (PG 16 mmHg) was recorded at another time.
PW Doppler distal to the mitral valve (diastole). Peak velocity: 1.75 m/s (PG ~12 mmHg). At another time, 2 m/s (PG 16 mmHg).
Continuous wave Doppler tracing across the LV, mitral valve, and LA. Peak systolic flow velocity from LV to LA is 3.72 m/s (PG 55 mmHg). This is less than expected — normally the PG would be ~100 mmHg.
CW Doppler (LV to LA, systole). Peak velocity: 3.72 m/s; PG = 55 mmHg. Lower than the expected ~100 mmHg.

Quiz

1. Using the modified Bernoulli equation, what would the blood flow velocity be if the pressure difference across the mitral valve was 100 mmHg?

2. There are two possible reasons the pressure gradient is decreased. One is decreased LV pressure. What is the other?

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