Quantitative, noninvasive assessment of patent ductus arteriosus shunt flow by measuring proximal isovelocity surface area on color doppler imaging

Abstract

Background: We evaluated the hemodynamic status of patent ductus arteriosus (PDA) by measuring vena contracta width (VCW) and effective shunt orifice area (ESOA) using proximal isovelocity surface area (PISA) on color Doppler imaging. Methods and Results: Study subjects were 21 patients with PDA (mean age, 3.6 years). We measured VCW (mm/m2) and ESOA (cm2) by the PISA method using echocardiography. Color images were obtained from parasternal long-axis views. VCW (mm/m2) was measured at the narrowest region of PDA flow. ESOA by PISA (PDA-ESOA) was defined on color Doppler flow imaging as a hemispheric area of laminar flow with aliased velocities [PDA-ESOA (cm2)=2π[PDA radius (cm)]^2×aligning velocity (cm/s)/PDA peak velocity (cm/s)]. Upon examining the relationships with catheterization parameters by univariate analysis, VCW correlated with diastolic blood pressure (DBP), % left ventricular end-diastolic volume (%LVEDV), pulmonary blood flow index, pulmonary blood flow/systemic blood flow ratio (Qp/Qs), left-right (LR) shunt ratio, left atrial to aortic root ratio (LA/AO), chest-thoracic ratio and N-terminal pro-brain natriuretic peptide (NTproBNP); and PDA-ESOA correlated with DBP, Qp/Qs, average pulmonary artery pressure, pulmonary/systemic pressure ratio, %LVEDV, LR shunt ratio, LA/AO and NTproBNP. When stepwise multiple linear regression analysis was performed with the correlations that were significant on univariate analysis, significant correlations with Qp/Qs were noted (VCW; R2=0.836, β=0.914, P<0.001, PDA-ESOA; R2=0.621, β=0.788, P<0.001). Conclusions: Measurement of VCW and PDA-ESOA by the PISA method can noninvasively evaluate the hemodynamic status of PDA.