Prediction of hemodynamic data in atrial septal defects of secundum type from simple and combined vectorcardiographic data

A search for simple and combined VCG data which could optimally predict right ventricular systolic pressure (RVSP) or shunt size was made in 50 patients with atrial septal defects of the secundum type. VCG was recorded by means of the axial lead system and a multiple regression computer program was applied. Fifty-four VCG data, age, sex, and systolic blood pressure were tested as independent predictors.Seventeen VCG data were significantly correlated with RVSP and six with flow. The best individual variable was the simple maximal negative deflection in Lead X (r = 0.64, p < 0.001). The correlations with flow were poorer, but of theoretical interest. Distinctive differences in the VCG-RVSP relationships were found in atrial septal defects compared with those in pulmonary stenosis, indicating that the increased flow sensitizes the right ventricle to the effect of pressure.Through multiple regression analysis, an equation based on four vectorcardiographic variables was derived. This equation improved the RVSP-VCG correlations significantly (p < 0.05, r = 0.80). The study confirms that vectorcardiogram is a reasonably reliable method for estimating RVSP in patients with atrial septal defects and that the use of combined VCG data may improve the method considerably.