STUDIES OF THE PULMONARY AND SYSTEMIC ARTERIAL PRESSURE IN CASES OF PATENT DUCTUS ARTERIOSUS WITH SPECIAL REFERENCE TO EFFECTS OF SURGICAL CLOSURE 1

Abstract

In 6 patients in whom preoperative cardiac catheterization studies were performed, the avg. flow through the patent ductus arteriosus was calculated to be 7.4 (1.6-17.7) l./min. Calculations based on the oxygen saturation of systemic arterial, pulmonary arterial and mixed venous blood samples obtained in 12 patients indicated that the avg. flow through the patent ductus arteriosus was 44 (23-80) % of the left ventricular output. The outside diam. of the ductus arteriosus in 9 of these cases averaged 9.9 (7.6-13) mm. Continuous, direct, radial arterial pressures in 7 patients with a patent ductus arteriosus and in 7 normal subjects recorded during standing, at rest and walking 1.7 and 3 miles/hr. showed on the avg. that the patients had a higher pulse pressure than the normal subjects, a moderately increased systolic pressure and a slightly decreased diastolic pressure. The changes in blood pressure produced by exercise were similar in patients before and after ligation of the ductus arteriosus and for practical purposes not different from those obtained in normal subjects. Exercise did not produce a decrease in diastolic pressure in these cases. The avg. pulmonary arterial pressures measured in 16 of the patients with patent ductus arteriosus were slightly elevated above the values reported for normal subjects. Closure of a patent ductus arteriosus in 15 patients produced an immediate increase in the systemic systolic and diastolic arterial pressure in every instance. There was also a significant, immediate decrease in the pulmonary arterial pressure.