Noninvasive estimation of systolic pressure in the right ventricle in patients with tricuspid regurgitation.

In 70 patients, tricuspid regurgitation was diagnosed with Doppler by recording reverse flow in systole originating at the tricuspid orifice, directed into the right atrium. The peak velocities were recorded, and the peak pressure drop from the right ventricle to the right atrium in systole was calculated from the simplified Bernoulli equation (pressure drop = 4 X 4 X Vmax2), and was found to correlate well with invasive measurements (r = 0.97, SEE +/- 6.1 mmHg). Central venous pressure was judged by neck vein congestion and added to the pressure drop to obtain a noninvasive estimation of systolic right ventricular pressure. Correlation with catheterization measurements was good (r = 0.96, SEE +/- 7.1 mmHg). In patients in whom the tricuspid regurgitation was judged as mild with Doppler, the correlation between noninvasive and invasive measurements of the transtricuspid pressure drop was still good (r = 0.95, SEE +/- 5.1 mmHg), indicating that the viscosity of the blood does not invalidate the use of the simplified Bernoulli equation when the regurgitant area of the valve is small.