INHIBITION OF CLOSURE OF THE DUCTUS ARTERIOSUS

Abstract

In many congenital cardiac lesions postnatal survival is dependent on ductus arteriosus(DA)patency. We studied a method for maintaining DA patency in lambs by formalin injection into its wall. In 10 late gestation fetal lambs, left thoracotomy was performed and 0.5-1.0 ml colored 10% formalin injected sub-adventitially along the ductal length; a pulmonary artery(PA) catheter was placed. 8 fetuses survived operation and delivered alive. Postnatally, catheters were placed in left ventricle, carotid and femoral arteries. Cardiac output and flow distribution were measured with radionuclide microspheres in 6 lambs. The lambs were killed 6 hrs-21 days postnatally. In normal lambs the DA is constricted within 12 hrs. 6 lambs with formalin-injected DA had mean PA pressures >60% aortic pressure and angiographic evidence of DA patency. All developed severe cardiac failure, and at autopsy had widely patent DA's. In 2 early studies the formalin injection was incomplete, and the DA was only probe patent. Histologically DA muscle showed various stages of fibrous replacement;intimal integrity was maintained. The DA was injected with formalin 6 hrs. after birth in 1 lamb which followed the same course as the 6 with large DA's. With this background we injected formalin into the DA in a newborn infant with tricuspid atresia in whom 3 surgical attempts to increase pulmonary flow were unsuccessful. Although the DA dilated and pulmonary flow increased, the infant died from pulmonary complications. NIH Grant HL06285