Several methods currently exist for quantifying pulmonary (Qp) and systemic (Qs) shunt flow using Doppler echocardiography, although none is widely utilized. In this study, 39 patients (age 2 months to 12 years, mean 2.1 years) underwent an echocardiographic examination within 1 month of Qp:Qs shunt flow determination by oximetry at catheterization. Qp:Qs was determined by 4 methods that utilized: (1) velocity time integrals 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 and aortic volume flow; and (4) ventricular septal defect (VSD) diameter and velocity time integral to calculate left-to-right shunt, which, when added to aortic volume flow (Qs), can be used to estimate Qp. Each of the first 3 methods was statistically correlated to the oximelry Qp: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, had the best correlation to catheterization data (r = 0.82), and further improved when 7 patients with a large VSD (>9 mm/m2), all of whom had bidirectional shunting, were removed (r = 0.90). Thus, we concluded that this latter method demonstrated the best correlation to catheterization-derived shunt flow data, and because this method is somewhat less labor-intensive than the others, should provide clinically useful data well suited for serial evaluation in infants and children with VSD.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine