Estimation of an Index of Right Ventricular Function with Echo-Doppler: Correlation with Pulmonary Pressure

pp. 87-94

Abstract

Background

Evaluation of right ventricular function usually requires the use of invasive methods to obtain parameters like pressure-volume curves to derive contractility indexes. The need of cardiac catheterization to obtain these data has limited to some extent the accesibility of this information. Thus, the availability of non invasive methods for the evaluation of right ventricular function would facilitate the acquisition of data. In pursuit of this objective, the purpose of our study was to investigate, in a group of patients with different pathologies, the utility of ultrasonic determination of functional right ventricular parameters, by obtaining the maximal dP/dt of the right ventricle by echo-Doppler to compare it with previously published invasive data. In addition, we studied the correlation of dP/dt with the systolic pulmonary pressure.

Material and method

Sixty consecutive patients with mild or moderate tricuspid insufficiency and normal systolic function of the right ventricle were studied prospectively with echo-Doppler. The systolic volumen of the right ventricle was calculated by this method.The maximal tricuspid regurgitation velocity was recorded. Maximal dP/dt was calculated as the quotient between two pressure-time points defined onthe regurgitant jet obtained by continuous Doppler. The differences between pressures P1 and P2was obtained by substracting two velocity values,V1 and V2 determined at 0.5 m/sec and 2 m/sec measured over the descending part of the curve and converted to right ventricle-right atrial pressure gradient using the simplified Bernoulli equation; the rate of right ventricular pressure rise was obtained as dP/dt asuming right atrial pressure variation negligible during early systole, even in thepresence of tricuspid regurgitation. The time interval between these two points was measured. Thepulmonary arterial pressure was calculated usingthe tricuspid regurgitant jet and the Bernoulli equation. The patients were separated in two groups. Group I: pulmonary systolic pressure < 35 mmHg; Group II: >_ 35 mmHg.

Results

The segmental motility of the right ventricle was normal by qualitative analysis of the echocardiogram. The systolic volume was 69 ± 19 ml/beat for the whole group, 72 ±20 ml/beat for group I and 65 ± 14 ml/beat for group II; without statistically significant differences. The systolic pulmonary pressure was 35 ±4 mmHg in the whole group: group I27.8 ± 5 and group II 50 ± 14, with a statistically significant difference between group I and groupII (p < 0.001, Student's test). The dP/dt maxim and pulmonary systolic pressure were: whole group r+ 0.16; group Ir=0.1; group II r=0.2.ConclusionsThe obtained value of the right ventricle maximal dP/dt, 365 mmHg/sec (170-750) is similar to that obtained previously by cardiac catheterization: 416 mmHg/sec (190-800). Due to the lack of correlation with the pulmonary systolic pressure, the dP/dt maxim of the right ventricle is an after load independent variable.