Patent Ductus Arteriosus

Abstract

T he patent ductus arteriosus (PDA) is a vascular structure that connects the proximal descending aorta to the roof of the main pulmonary artery near the origin of the left branch pulmonary artery. This essential fetal structure normally closes spontaneously after birth. After the first few weeks of life, persistence of ductal patency is abnormal. The physiological impact and clinical significance of the PDA depend largely on its size and the underlying cardiovascular status of the patient. The PDA may be "silent" (not evident clinically but diagnosed incidentally by echocardiography done for a different reason), small, moderate, or large. Regardless of the size, complications may arise, and it is important for both pediatric and adult cardiologists to have an understanding of the pathophysiology, clinical implications, and management of PDA. EmbryologyThe ductus arteriosus is a normal and essential fetal structure that becomes abnormal if it remains patent after the neonatal period. In normal cardiovascular development, the proximal portions of the sixth pair of embryonic aortic arches persist as the proximal branch pulmonary arteries, and the distal portion of the left sixth arch persists as the ductus arteriosus, connecting the left pulmonary artery with the left dorsal aorta (Figure 1). Normally, the distal right sixth aortic arch loses its connection to the dorsal aorta and degenerates. This transformation is complete by 8 weeks of fetal life. Normal Physiology Fetal CirculationWhereas Ϸ65% of the fetal cardiac output is from the right ventricle, only 5% to 10% passes through the lungs. 1,2 The preponderance of right ventricular output passes through the ductus arteriosus into the descending aorta. The fetal ductus arteriosus is thus an important structure that is essential for normal fetal development, permitting right ventricular output to be diverted away from the high-resistance pulmonary circulation. Premature constriction or closure may lead to right heart failure, resulting in fetal hydrops. 3 Histology and Mechanisms of Normal ClosureGrossly, the constitution of the fetal ductus arteriosus appears to be similar to the contiguous main pulmonary artery and descending aorta; there are important histological differences, however. 4 -9 Whereas the mediae of surrounding aorta and pulmonary artery are composed mainly of circumferentially arranged layers of elastic fibers, the media of the ductus arteriosus is composed of longitudinally and spirally arranged layers of smooth muscle fibers within loose, concentric layers of elastic tissue. The intima of the ductus arteriosus is thickened and irregular, with abundant mucoid material, sometimes referred to as intimal cushions.Fetal patency of the ductus arteriosus is controlled by many factors, the most important of which are relatively low fetal oxygen tension 10 and cyclooxygenase-mediated products of arachidonic acid metabolism (primarily prostaglandin [PGE 2 ] and prostacyclin [PGI 2 ]). 11 Locally produced and circulating PGE 2 and PGI 2 in the fetus cau...

Persistent Ductus Arteriosus in Critically Ill Preterm Infants

“…Ductus arteriosus (DA), described for the first time by Galen in the first century is an important vascular structure of the fetal circulation, connecting the proximal ascendant aorta to the pulmonary artery root, close to the left pulmonary branch artery [1,2]. After birth, as part of the transition to extra uterine life, the ductus closes due to increased arterial oxygen pressure, decreased pressure of the pulmonary blood flow, decreased concentration of prostaglandin E2, and decreased the number of the prostaglandin E2 receptors [3,4].…”

“…At term, spontaneous functional closure of DA occurs in 50% of the infants at 24 hours, in 90% of the cases at 48 hours, and in 100% of the cases at 72 hours of life [5,6]. Anatomical closure of the ductus occurs in 2-3 weeks [2]. Closure of DA often fails in preterm infants, mostly due to developmental immaturity [2,6].…”

“…Anatomical closure of the ductus occurs in 2-3 weeks [2]. Closure of DA often fails in preterm infants, mostly due to developmental immaturity [2,6].…”

“…In "term infants, " PDA occurs in 0.3-4/1000 live births at the end of the neonatal period, representing 5-10% of the congenital heart defects [2,10,11]. Sometimes PDA accompanies congenital ductal-dependent heart defects and closure of the PDA soon after birth may precipitate clinical deterioration [12].…”

Complicaciones digestivas y renales por indometacina e ibuprofeno en prematuros extremos con ductus arterioso permeable

“…International data show that 55% of premature infants under 1,000 g have PAD requiring medical treatment 4 . The closure of the ductus is late in the extreme premature patients (EP), generally beyond the first week of life, due to a smaller number of muscle fibers and sub-endothelial tissue, also delaying the closure or reopening in situations of systemic inflammation 5 .…”