Hetzel, Peter S.

The possibility of measuring pulmonary blood flow in patients with central arteriovenous shunts utilizing the initial portion of indicator-dilution curves was explored in 16 patients by comparing these values for pulmonary blood flow with determinations by the direct Fick method. A good correlation between Fick and indicator-dilution values was obtained, and no systematic differences were demonstrated. The standard deviation of the differences between Fick and dye values was in the order of 20 to 25 per cent.

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.

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.