[Evaluation of aortic to pulmonary blood flow ratio by Doppler echocardiography in septal defects].

Pulsed Doppler-echocardiography was used to measure systemic and pulmonary blood flows in 22 patients aged from 3 months to 62 years presenting with interatrial (n = 13) or interventricular (n = 9) septal defect. Calculations were based on echographic measurements of aortic and pulmonary orifice areas and on the integral of maximal aortic and pulmonary Doppler velocity curves. Section areas or the arteries, taken as being circular, were deduced from arterial diameter measurements effected above Valsalva's sinus. Doppler velocity curves were recorded at that level, looking for maximal velocities and assuming a flat velocity profile. Blood flow ratios evaluated from Doppler-echocardiography data were compared with data provided by oximetry and showed good correlations (r = 0.92; Y = 0.71x + 0.53; SEE = 0.24). Calculations by categories of lesions showed better results in patients with interatrial septal defect (r = 0.94; Y = 0.73x + 0.507; SEE = 0.22) than in patients with interventricular septal defect (r = 0.83; Y = 0.547x + 0.75; SEE = 0.25). The main difficulties encountered in measuring Doppler-echocardiography blood flow ratios concerned accurate measurement of pulmonary artery diameter, due to problems of lateral resolution, and accurate measurement of turbulent Doppler velocimetry curves. However, this new, non-invasive technique may be useful to determine the best indications for catheterization or even surgery.