COMPARISON OF 4 DOPPLER-ECHOCARDIOGRAPHIC METHODS FOR CALCULATING PULMONARY-TO-SYSTEMIC SHUNT FLOW RATIOS IN PATIENTS WITH VENTRICULAR SEPTAL-DEFECT

Several methods currently exist for quantifying pulmonary (Qp) and sys temic (Qs) shunt flow using Doppler echocardiography, although none is widely utilized. In this study,, 39 patients (age 2 months to 12 year s, mean 2.1 years) underwent an echocardiographic examination within 1 month of Qp:Qs shunt flow determination oximetry at catheterization. Qp:Qs was determined 4 methods that utilized: (1) velocity time integr als and luminal areas to estimate volume flow of the pulmonary artery and aorta; (2) the square of the ratios of pulmonary artery to aorta, multiplied by the ratio of pulmonary to aortic peak flow velocities; ( 3) inclusion of mitral and tricuspid valve volume flow to pulmonary an d aortic volume flow; and (4) ventricular septal defect (VSD) diameter and velocity time integral to calculate left-to-right shunt, which, w hen added to aortic volume flow (Qs), can be used to estimate Qp. Each of the first 3 methods was statistically correlated to the oximetry Q p:Qs, with r values ranging from 0.54 to 0.66 (p <0.001). However, the fourth method, based on direct computation of flow across the VSD, ha d the best correlation to catheterization data (r = 0.82), and further improved when 7 patients with a large VSD (>9 mm/m(2)), all of whom h ad bidirectional shunting, were removed (r = 0.90). Thus, we concluded that this latter method demonstrated the best correlation to catheter ization-derived shunt flow data, and because this method is somewhat l ess labor-intensive than the others, should provide clinically useful data well suited for serial evaluation in infants and children with VS D.