QUANTITATIVE, NONINVASIVE ASSESSMENT OF VENTRICULAR SEPTAL-DEFECT SHUNT FLOW BY MEASURING PROXIMAL ISOVELOCITY SURFACE-AREA ON COLOR DOPPLER MAPPING

Objective-To determine whether the proximal isovelocity surface area ( PISA) method could be applied to estimate the magnitude of ventricular septal defect (VSD) shunt flow. Design-Prospective analysis of clinic al, echocardiographic, and angiographic data. Setting-University hospi tal. Patients-14 children with VSD. Methods-Colour Doppler images of V SD shunt flow were obtained in parasternal long axis view, four chambe r view or both, adjusted to provide the best imaging of flow. The VSD shunt flow rate and shunt volume were calculated as follows: shunt flo w rate (SFR) = 2 pi r(2) V/BSA in ml/s/m(2); shunt volume = SFR x shun t duration time. The shunt volume, shunt fraction, and pulmonary to sy stemic flow ratio (Qp:Qs> were confirmed by cardiac catheterisation. R esults-There was a correlation between shunt variables determined by P ISA and those by catheterisation, including shunt volume (r = 0.78, P = 0.001) and shunt fraction (r = 0.74, P = 0.003). Qp:Qs was also sign ificantly correlated with SFR (r = 0.79, P = 0.0007). The SFR was sign ificantly different between the four patients with Qp:Qs < 2.0 (mean ( SD) 54 (33) ml/s/mz) and the 10 patients with Qp:Qs > 2.0 (186 (69) ml /s/m(2)) (P = 0.004). Conclusions-These data suggest that the PISA met hod is a reliable non-invasive investigation for the quantitative asse ssment of VSD shunt flow and provides important information for decisi ons regarding surgical repair.