Noninvasive measurement of right ventricular systolic pressure by combined color-coded and continuous-wave Doppler ultrasound

Noninvasive prediction of right ventricular (RV) pressure is a clinical challenge.1–4 Doppler echocardiography is now routinely used to assess pulmonary hypertension.5–10 Measurement of the flow velocity of tricuspid regurgitation is of great value in the evaluation of RV peak pressure. Without a pressure difference across the pulmonary valve, peak pressure in the pulmonary artery can be calculated from the flow velocity of the tricuspid regurgitation. Correlations with catheterization data are reasonably good, although in most studies extreme values are included in the calculations and this may result in unrealistically good correlations with catheterization data. Without visualization of the direction of the tricuspid regurgitation, underestimation of RV peak pressure can be expected in a number of patients because the direction of the tricuspid regurgitation flow is not necessarily the same as the Doppler sound beam. One still needs to search and listen for audio Doppler signals to record the measured maximal velocity. We undertook this study, therefore, attempting to answer the following questions: (1) Can continuous-wave (CW) Doppler alone accurately predict the RV peak pressure and what would be the correlation between Doppler and catheterization data in that most interesting group of patients, those with moderately elevated RV peak pressures? (2) Is the angle between the visualized tricuspid regurgitation with color-coded [CC) Doppler and the CW beam of importance for accurate measurement of the RV peak pressure? (3) In what percentage of patients can pulmonary hypertension be suspected by auscultation or phonocardiography?