Case 4 — Doppler Echocardiogram

Continuous wave (CW) Doppler echocardiogram with transducer at the left ventricular apex. The 2D guidance image above the spectral trace shows the CW beam cursor crossing the left ventricular outflow tract and out the aorta (AO). Blood flow is below the baseline (away from transducer, normal direction). Peak velocity is markedly increased at 5.3 meters per second, corresponding to a pressure gradient of 112 mmHg across the subaortic obstruction (normal gradient less than 10 mmHg).
CW Doppler from the left ventricular apex across the left ventricular outflow tract and aorta (AO). Peak velocity 5.3 m/s; pressure gradient 112 mmHg.

This is a continuous wave (CW) Doppler which measures the peak velocity of a high-velocity jet. The orientation of the cursor can be seen in the two-dimensional image above the CW image. The transducer has been placed at the left ventricular apex and the CW beam originates there, crosses the left ventricular outflow tract, and passes out the aorta (AO). Blood flow direction is away from the transducer (below the line) and so is oriented normally. Normal blood flow velocity in this region is 1 to 2 meters/second. The velocity in this dog is markedly increased to 5.3 meters/second. This velocity translates into a pressure gradient (difference) across this region of 112 mmHg (normal pressure gradient is less than 10 mmHg).

Quiz

1. If the systolic pressure in the proximal aorta is 120 mmHg, what is the systolic pressure in the left ventricle in this dog?

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