Case Studies In Small Animal

Cardiovascular Medicine

Case 20

Doppler echocardiograms

The cursor for this pulsed wave Doppler tracing has been placed immediately distal to the mitral valve. Note that flow is toward the transducer (above the line) and that it is occurring in diastole (it starts after the T wave and well after the QRS complex). The peak velocity in early diastole is higher than normal at 1.75 meters/second. This translates into a pressure gradient across the mitral valve region of approximately 12 mmHg, which is also increased. A peak velocity of 2 meters/second was recorded at another time corresponding to a pressure gradient of 16 mmHg (2 squared times 4 using the modified Bernoulli equation).

This is a continuous wave Doppler trace. The cursor starts at the transducer and projects across the left ventricle, mitral valve region, and left atrium. The peak flow velocity from the left ventricle to the left atrium in systole has been measured to be 3.72 meters/second. The pressure gradient, based on this flow velocity, is 55 mmHg. This pressure difference is less than one would expect. Normally the left ventricular systolic pressure is approximately 110 mmHg while the systolic pressure in the left atrium is less than 10 mmHg. This means the pressure gradient is around 100 mmHg.

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©Mark D. Kittleson, D.V.M., Ph.D. All rights reserved.