Chapter 72

#### Patent Ductus Arteriosus

Key Points

1. Full-term neonates, infants, and older children should have patent ductus arteriosus (PDA) closed even in the absence of symptoms, provided the pulmonary vascular resistance is less than 8 to 10 wood units/m2.

2. Ligation is reserved for preterm infants and small newborns.

3. In full-term newborns and older children, the ductus arteriosus is divided whenever possible to avoid the rare complications of ductal recanalization or aneurysm formation following ligation.

4. Closure using the midline sternotomy approach is most commonly employed for patients requiring cardiopulmonary bypass to correct a coexisting cardiac lesion.

5. On rare occasions when the PDA cannot be encircled, it can be closed from inside the main pulmonary artery.

6. The double-umbrella and vascular occluder are currently used for percutaneous catheter closure of PDA and Gianturco coils are becoming increasing popular.

7. Endoscopic ductal closure can be applied to patients less than 3 to 5 kg, an important distinction from transcatheter closure, where femoral vessel size may be prohibitive.

8. Complications of PDA closure include bleeding and aneurysm of the ductus arteriosus after ligation or division.

9. The high complication rate following ductus ligation in preterm infants is related more to prematurity than to the surgery. About 5% to 10% of these premature patients develop sequellae, including retrolental fibroplasia, blindness, and cerebral palsy.

#### Introduction

The ductus arteriosus is a vessel 5 to 10 mm in length that connects the main pulmonary trunk with the descending aorta just distal to the origin of the left subclavian artery. An embryologic remnant of the distal portion of the sixth left branchial arch, the ductus arteriosus is usually on the left side, but in cases of right aortic arch, it can be on either side. It is rarely completely absent or bilateral.

#### Embryology and Pathologic Anatomy

The media of the ductus at birth is composed of circularly arranged smooth muscle cells that contract in response to increasing oxygen tension. The first stage of postnatal closure occurs at 10 to 15 hours after birth and the final stage is complete at 2 to 3 weeks in 88% of full-term infants. Although final closure may occur at any age, it is distinctly uncommon beyond 6 months of life. Beyond 1 year of age, about 1% of all ducti remain open and very few close after that.

In the premature newborn with a birth weight of 1000 g or less, the incidence of patent ductus arteriosus (PDA) is 80% to 90%. This high incidence is related to decreased smooth muscle in the ductal wall, diminished response of the muscle to oxygen, and increasing levels of E series prostaglandins, which vasodilate the ductal muscle and prevent closure.

#### Natural History, Mortality, and Morbidity

The incidence of isolated PDA in a full-term infant is 1/2000 live births and represents 5% to 10% of all types of congenital heart ...

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