Estimation of the right ventricular volume overload in children with atrial septal defect by body surface mapping.

To investigate the possibility of estimating the right ventricular volume overload in atrial septal defect (ASD) by body surface mapping (BSM), 45 children with ASD were included in the present study. The breakthrough minimum (BTM) appeared later and more leftward in ASD subjects than in the normal controls. Neither the length of the delay in the appearance of the BTM nor the extent of its leftward deviation was significantly correlated with the pulmonary and systemic flow volume ratio (Qp/Qs), obtained by cardiac catheterization. Therefore neither could be used as the parameter of the right ventricular volume overload. sigma R, Rmax (D3 + D4) + magnitude of S max (H4 + H5) and "T dep", the sum of the absolute values of the departure indices (DIs) in the G4, G5, H4 and H5 leads, and the DIs in the J5, J6, K5, and K6 leads in T departure Map, correlated with the Qp/Qs significantly (r = 0.62, 0.68, 0.69, respectively). Accordingly, they might be useful for estimating the right ventricular volume overload. The subjects were divided into 3 groups according to their Qp/Qs. Discriminant analysis between these 3 groups was then performed, using Rmax (D3), magnitude of S max (H4), and T dep as the variables. The accuracy of this discrimination was 82.2%. The results suggest the possibility of estimating the severity of ASD by BSM.