Estimation of pulmonary vascular resistance in patients with ventricular septal defects by echo-Doppler cardiography.

The pulmonary vascular resistance is one of the parameters considered in the evaluation of patients with ventricular septal defects. We describe a new method to estimate resistance. The method estimates the systolic resistance in the pulmonary circulation and we assume that there is a linear relation between this resistance and the traditional resistance in which a continuous flow in systole and diastole is assumed. The systolic resistance was compared to the traditional resistance index in a group of patients whose invasive data were evaluated retrospectively. A close correlation between the two estimates of resistance was found and when the results were applied to another group of patients examined non-invasively and invasively there was no significant difference between the invasive resistance index and the non-invasive estimate arrived at by the new method.