A B S T R A CT Experiments were performed to evaluate the role of prostaglandin synthesis in the regulation of coronary blood flow in dog hearts. The left main coronary artery was cannulated and flow measured both in otherwise intact animals and in canine heart-lung preparations. Prostaglandin E was measured by radioimmunoassay. Reactive hyperemia (flow after occlusion release) was induced by coronary occlusion for 10, 15, and 20 s and was 39±13 (mean±SEM), 66+21, and 82±24 ml, respectively. Indomethacin, an inhibitor of prostaglandin synthetase, reduced reactive hyperemia at 10, 15, and 20 s to 15-+-5, 33+11, and 47+17 ml, respectively (P <0.05). Meclofenamate, a different prostaglandin synthetase inhibitor, gave similar results. In a second group of five dogs, prostaglandin production of the heart was examined in response to 20-s occlusions.There wvas a significant increase in prostaglandin production from a basal level of 18.6±4.9 ng/min to 35.3+ 5.8 ng/min after occlusion of the coronary artery for 20 s (P < 0.05). After indomethacin, this increase in prostaglandin production was not observed and reactive hyperemia was significantly reduced. Thus, prostaglandin synthesis appears to be important in modulating canine coronary blood flow in response to brief periods of coronary occlusion.
Clinical and morphological findings are described in 2 adults with combined valvular pulmonary and aortic stenosis with atrial septal defect, an extremely rare combination of lesions. The direction of the shunt via the atrial septal defect in this combination appears to be dependent on the relative degree of outflow obstruction on the right side compared with the left side of the heart. In 1 patient the degree of obstruction at the pulmonary valve was nearly three times that at the aortic valve and, therefore, the shunt was right to left and the patient was severely cyanotic. In the other patient, the degree of obstruction at the pulmonary valve was slightly less than that at the aortic valve and, therefore, the shunt was entirely left to right and the patient was acyanotic. Diagnosis of an associated obstructive lesion on the left side of the heart in a patient with an obstructive lesion on the right side of the heart is essential because operative relief of the right-sided obstruction without relief of the left-sided obstruction may lead to rapid, fatal pulmonary congestion.
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