Determination of the anatomical size of ventricular septal defects on the basis of hemodynamic data and noninvasive assessment of pulmonary to systemic vascular resistance ratio rp/rs by doppler-echocardiography

The pulmonary and systemic flow (Qp/Qs) and resistance ratios (RP/Rs) were determined in children with isolated ventricular septal defects (VSD) to derive an “effective defect resistance” (Rd/Rs) representing the ratios of the resistance of the defect to the systemic vascular resistance. The defect size (expressed as the ratio of the area of the defect to the cross‐sectional area of the ascending aorta) was related to the calculated “effective defect resistance,” where a significant (non‐linear) correlation was found. The effective resistance of the defect is a useful aid for estimation of the anatomical size of a ventricular septal defect. The close correlation between anatomical size and the hemodynamic parameter Rd/Rs allows one to calculate the ratio Rp/Rs with this concept using nonin‐vasive Doppler‐ultrasound and echocardiography. This was performed in 21 children with VSD who underwent cardiac catheterisation. The noninvasive calculated flow ratio Qp/Qs and the resistance ratio Rp/Rs showed a close correlation to the values measured at cardiac catheterisation.