Anesthesia for Patients With Patent Ductus Arteriosus

Excerpt

The ductus arteriosus (DA) plays a crucial role in fetal circulation. The ductus usually undergoes spontaneous "functional" closure from smooth muscle constriction within 18-24 hours after birth. Anatomical closure of the ductal lumen will usually be complete by 2-3 weeks of age. The spontaneous closure of the ductus soon after birth can be interrupted or delayed, leading to a patent ductus arteriosus (PDA). Rarely, a PDA can even be discovered as a cardiac defect in adults. A PDA is a fetal shunt that allows blood flow between the aorta and the pulmonary artery. Some factors that can lead to a PDA include hypoxemia, low Apgar scores, prenatal Rubella exposure, mechanical ventilation, and prematurity. Approximately 80% of neonates with a gestational age of 25 to 28 weeks will develop a PDA. PDA is a commonly encountered cardiac defect for pediatric anesthesiologists. This defect accounts for 6-11% of all congenital cardiac lesions. Preterm infants have a 20-60% incidence of PDA development versus 0.2% to 0.4% incidence of PDA with term birth. Females are also found to have a PDA twice as often as males.

In preterm infants, the PDA leads to systemic hypoperfusion and over-circulation of the pulmonary vasculature. Also, PDA is associated with necrotizing enterocolitis (NEC), prolonged mechanical ventilation, bronchopulmonary dysplasia (BPD), intraventricular hemorrhage, and neurodevelopmental delays. Treatment options include conservative therapy such as non-steroidal anti-inflammatory drugs (NSAIDs) and fluid restriction, or more invasive treatments such as surgical ligation or device closure in the cath lab.

Infants with a ductal dependent congenital heart defect will need the ductus to remain open for survival before undergoing surgical correction of their cardiac lesions. An infusion of prostaglandin E1 is used to maintain ductal patency in these patients. These fragile infants will often require anesthesia for surgical procedures such as central line placement, exploratory laparotomy, congenital cardiac defect repair, PDA closure, and other neonatal emergencies. The anesthesiologist needs to understand the pathophysiology of this extracardiac left to right shunt and be able to manipulate ventilation, drugs, and perfusion to maintain a balance between systemic and pulmonary circulations.