DRAINAGE PATHWAYS OF PULMONARY VEINS IN ATRIAL SEPTAL DEFECT

At the present time a variety ofmethods is available for the closure of atrial septal defects; these include closed techniques, semi-open procedures utilizing an atrial well, and open repair with the aid of either general hypothermia or extracorporeal circulation. Since approximately 15 to 20 per cent of patients with atrial septal defect have associated partial anomalous pulmonary venous drainage into the superior vena cava or right atrium (Kirklin et al., 1956 and Gilman et al., 1957), its pre-operative recognition is desirable in the intelligent selection of patients for operation and in planning the surgical procedure itself. Detailed anatomical and physiological assessment is particularly important if extracorporeal circulation is not employed routinely in the closure of atrial septal defects. The information derived from the clinical examination, electrocardiogram, roentgenogram, angiocardiogram, and usual cardiac catheterization studies has been found to be of relatively little value in determining the site of drainage of pulmonary veins. In the course of the cardiac catheterization, the catheter may frequently be manipulated into one or more pulmonary veins, but even the position of the catheter as determined by fluoroscopic examination is not usually decisive, since it may be impossible to determine whether or not it has traversed the defect before entering the pulmonary vein. The indicator dilution curve, obtained from a peripheral artery after injection into a pulmonary vein, makes possible the precise determination of the drainage path of the vein. The basis for this diagnostic approach has been described in reports by Swan et al. (1953 and 1957) and Swan and Wood (1957), and from this clinic (Grant et al., 1957; Baker et al., 1958; Braunwatd et al., 1958). Following the injection of an indicator into a pulmonary vein that drains normally into the left atrium, the arterial dilution curve closely resembles the curve obtained following left atrial injection, in respect to both appearance time and contour. If, on the other hand, the vein drains into the right atrium or into a systemic vein, the dilution curve will resemble that obtained following right atrial injection. It is the purpose of this communication to present the results of the application of this technique in 29 patients with atrial septal defect in whom the site of drainage of the pulmonary veins was subsequently confirmed at open operation. The operations were performed under direct vision with the aid of extracorporeal circulation in all but two patients in whom general hypothermia was utilized.