Contrast echocardiographic evaluation of changes in flow velocity in the right side of the heart.

We used contrast echocardiography to estimate changes in flow velocity at the tricuspid and pulmonic valve orifices, as reflected by varying angles of the moving linear contrast echoes. The validity of the method was established by catheterization and echocardiographic studies in 14 patients. Flow velocity at the tricuspid and pulmonic valve orifices was measured by means of an electromagnetic flow-velocity probe, and the contrast echocardiogram was recorded simultaneously. Instantaneous changes in contrast flow velocity as measured by the contrast echo angle correlated significantly with flow velocity changes measured by the probe at the tricuspid valve orifice (mean r = 0.87) and at the pulmonic valve orifice (mean r = 0.92). In all 26 subjects (12 normals and 14 patients with heart disease) studied in the noninvasive laboratory, the effects of simple interventions that modify right-sided flow were observed. The contrast flow velocity at the tricuspid valve orifice in 12 normal subjects was 345 ± 30 mm/sec and was reproducible by repeated injections. The contrast flow velocity changed with respiration and heart rate, and was most rapid with inspiration. A 10% increase in heart rate resulted in a 45% average increase in contrast flow velocity. The contrast flow velocity began to increase immediately after 450 passive rapid elevation of both legs, and the maximal increase during this 5-second maneuver averaged 40%; thereafter, it gradually decreased and returned to the control level within 2 seconds after the legs were lowered to the horizontal position. We conclude that the linear contrast echo obtained by contrast echocardiography is relatively easy to achieve, reliable and reproducible and that it facilitates evaluation of instantaneous changes in flow velocity in the right side of the heart, assuming that careful attention is given to the techniques of recording and measurement. Absolute flow velocity is more accurately measured for the pulmonary valve than for the tricuspid valve with this method. Changes in flow through either valve may be assessed by this means when interventions are applied.