A new formula for echo-Doppler estimation of right ventricular systolic pressure

The Doppler formulas currently used for right ventricular systolic pressure (RVSP) evaluation include right ventricular—right atrial (RV-RA) gradient and RA pressure. The former is expressed by the velocity of the transtricuspid regurgitant flow; the latter is generally assumed and is different from one formula to another. In 110 patients with cardiac disease with normal or elevated pulmonary pressure, we tested a new echo-Doppler formula for the evaluation of RVSP based on the estimation of RA pressure by means of the inferior vena cava collapsibility index (IVCCI) and compared this method with two traditional formulas (methods A and B) and with cardiac catheterization values. Patients were classified into three groups on the basis of IVCCI (group 1 > 45%, group 2 between 35% and 45%, and group 3 < 35%). RVSP was evaluated by method A (RV-RA gradient + 10), method B (RV-RA gradient × 1.1 + 14), and our new method, method C, which assigns 6, 9, and 16 mm Hg to RA pressure in the presence of normal (>45%), moderately reduced (between 35% and 45%), or markedly reduced (<35%) IVCCI, respectively. IVCCI correctly identified RA pressure in the three groups (group 1, 6.8 mm Hg; group 2, 10.8 mm Hg; and group 3,13.1 mm Hg); a high correlation existed between Doppler-derived and invasively determined RV-RA gradient (r= 0.99). Method C improved noninvasive estimation of RVSP in groups 1 and 3 compared with the other methods; in group 2, Doppler estimation of RVSP by methods A and C were comparable, whereas method B significantly overestimated the acutal values. In conclusion, this new method, based on prediction of RA pressure through IVCCI, improves Doppler estimation of RVSP, particularly in patients with low or elevated RA pressure, and may be applied to unselected patients with normal or elevated pulmonary pressure, independently of the cause of cardiac disease.