Swan, H.J.C.

Anomalous connection of the right pulmonary veins to the superior vena cava associated with an interatrial communication in an unusually cephalad location has been diagnosed at cardiac catheterization in 8 patients. These patients had the clinical features seen in patients who have atrial septal defects in the region of the fossa ovalis. Differentiation was accomplished by (1) the roentgenographic position of the catheter in the right superior pulmonary vein, (2) demonstration of an abnormally high oxygen saturation of the blood in the superior vena cava, (3) the presence of a small right-to-left shunt from the superior vena cava and the absence of such a shunt from the inferior vena cava, and (4) demonstration of similar drainage of blood from the right superior pulmonary vein and superior vena cava. The syndrome is considered to be an anomaly of pulmonary venous development while the atrial septum forms normally.

Seven cases of patent ductus arteriosus with pulmonary hypertension and reversal of the usual direction of flow are described. Breathing of a low oxygen mixture either initiated or increased the reversed shunt, and breathing 100 per cent oxygen produced the reverse effect. Differences in oxygen saturation and dye-dilution curves recorded simultaneously from the radial and femoral arteries have allowed calculation of differences in the proportion of shunted blood flowing in these arteries and demonstrate that retrograde movement of blood in the aortic arch may occur.

Use of cuvette and earpiece oximeters facilitates the recording of the immediate dilution pattern of the dye T-1824 (Evans blue) in the arterial blood. In patients with venoarterial shunts the pattern of the dilution curves differs from normal. Quantitative analysis of such curves from patients with cyanotic congenital heart disease has been undertaken to establish the proportion of blood which bypassed the pulmonary circulation. The results obtained have been compared with estimates of the volume of the shunt from cardiac catheterization data and related to the arterial oxygen saturation.

Arterial dilution curves of T-1824 have been recorded by oximeters after injection of T-1824 into both the right and left pulmonary arteries in patients with anomalous connections of the pulmonary veins, with atrial septal defects or with persistent common atrioventricular canals. The most extreme differences were found between the pairs of curves in the patients with the anomalous connection. These differences were less pronounced but clearly recognizable in the other conditions, and suggested a more general use of the term "anomalous pulmonary venous drainage. "The findings indicate that, in the usual case of atrial septal defect, a greater proportion of the blood from the right lung passes to the right atrium than does blood from the left lung.

Patients who have pulmonary stenosis and ventricular septal defect usually have a right-to-left intracardiac shunt. This paper presents hemodynamic and clinical data on 11 patients who have pulmonary stenosis, ventricular septal defect and left-to-right shunts. Four of these patients also have defects in the atrial septum, and three have demonstrable bidirectional shunts. The level and direction of shunts were determined by blood oxygen-saturation data and indicator-dilution studies. Choice of the form of treatment to be used in patients such as these should be based largely on hemodynamic considerations. Many resemble patients with tetralogy of Fallot who have had a successful pulmonary valvotomy.

Evidence is presented which indicates that shunting of small amounts of blood from right to left occurs frequently through interatrial communications. Such right-to-left shunts are of small magnitude in the usual case of atrial septal defect, but it appears that of the fractions of blood shunted, a greater proportion has originated from the inferior vena cava than from the superior vena cava.

A method based on the initial portion of indicator-dilution curves has been used to determine the proportion of blood from each lung which drains anomalously. The results obtained appear to substantiate the derivation and permit the expression, in numerical values, of the greater proportion of anomalous drainage of blood from the right lung in the usual case of atrial septal defect. The principal assumptions pertaining to the method are discussed in some detail.