Patent ductus arteriosus
Patent ductus arteriosus is a medical condition in which the ductus arteriosus fails to close after birth: this allows a portion of oxygenated blood from the left heart to flow back to the lungs from the aorta, which has a higher blood pressure, to the pulmonary artery, which has a lower blood pressure. Symptoms are uncommon at birth and shortly thereafter, but later in the first year of life there is often the onset of an increased work of breathing and failure to gain weight at a normal rate. With time, an uncorrected PDA usually leads to pulmonary hypertension followed by right-sided heart failure.
The ductus arteriosus is a fetal blood vessel that normally closes soon after birth. This closure is caused by vessel constriction immediately after birth as circulation changes occur, followed by the occlusion of the vessel's lumen in the following days. In a PDA, the vessel does not close, but remains patent, resulting in an abnormal transmission of blood from the aorta to the pulmonary artery. PDA is common in newborns with persistent respiratory problems such as hypoxia, and has a high occurrence in premature newborns. Premature newborns are more likely to be hypoxic and have PDA due to underdevelopment of the heart and lungs.
If the congenital defect transposition of the great vessels is present in addition to a PDA, the PDA is not surgically closed since it is the only way that oxygenated blood can mix with deoxygenated blood. In these cases, prostaglandins are used to keep the PDA open, and NSAIDs are not administered until surgical correction of the two defects is completed.
In full-term newborns, PDA occurs in 1 in 2,000 births, and accounts for 5–10% of congenital heart disease cases. PDA occurs in 20–60% of all premature newborns, where its incidence is inversely linked with gestational age and weight.
Signs and symptoms
Common symptoms include:Signs include:
- tachycardia
- continuous "machine-like" heart murmur
- cardiomegaly
- left subclavicular thrill
- bounding pulse
- widened pulse pressure
- increased cardiac output
- increased systolic pressure
- poor growth
- differential cyanosis, i.e. cyanosis of the lower extremities but not of the upper body.
Risk factors
Known risk factors include:- Preterm birth
- Congenital rubella syndrome
- Chromosomal abnormalities
- Genetic conditions such as Loeys–Dietz syndrome, Wiedemann–Steiner syndrome, and CHARGE syndrome.
- Fetal alcohol spectrum disorder
Diagnosis
A chest X-ray may be taken, which reveals overall heart size and the appearance of blood flow to the lungs. A small PDA most often accompanies a normal-sized heart and normal blood flow to the lungs. A large PDA generally accompanies an enlarged cardiac silhouette and increased blood flow to the lungs.
Prevention
Some evidence suggests that intravenous NSAIDs, such as indomethacin, administration on the first day of life to all preterm infants reduces the risk of developing a PDA and the complications associated with PDA. Intravenous indomethacin treatment in premature infants also may reduce the need for surgical intervention. Administering ibuprofen probably helps to prevent PDA and reduce the need for surgery but it also likely increases the risk of kidney complications.Treatment
Symptomatic PDA can be treated with both surgical and non-surgical methods.Conservative
Neonates without adverse symptoms may simply be monitored as outpatients.Surgery
Surgically, the DA may be closed by ligation. This can either be performed manually and be tied shut, or with intravascular coils or plugs that leads to formation of a thrombus in the DA.Devices developed by Franz Freudenthal block the blood vessel with woven structures of nitinol wire. Newer procedures performed effectively in older, bigger children include catheter PDA occlusion and video-assisted thoracoscopic PDA clipping.
Prostaglandin inhibitors
Because prostaglandin E2 is responsible for keeping the DA open, NSAIDs such as indomethacin or a special form of ibuprofen have been suggested as therapy to initiate PDA closure. Findings from a 2015 systematic review concluded that, for closure of a PDA in preterm and/or low birth weight infants, ibuprofen is as effective as indomethacin. It also causes fewer side effects and reduces the risk of necrotising enterocolitis. The evidence supporting the effectiveness and safety of paracetamol is less clear. A review and meta-analysis showed that paracetamol may be effective for closure of a PDA in preterm infants. A 2018 network meta-analysis that compared indomethacin, paracetamol and ibuprofen at different doses and administration schemes among them found that a high dose of oral ibuprofen may offer the highest likelihood of closure in preterm infants. However, a 2020 systematic review found that early or very early pharmacological treatment of symptomatic PDA does not reduce death or other poor clinical outcomes in preterm infants but instead increases their exposure to NSAIDS. Vasodilator therapy is suitable for people with Eisenmenger physiology. To assess improvement in people with Eisenmenger physiology, close monitory of toe oxygen saturation is required, for there exists a chance of reversal after a successful right-to-left shuntWhile indometacin can be used to close a PDA, some neonates require their PDA be kept open. Keeping a ductus arteriosus patent is indicated in neonates born with concurrent heart malformations, such as transposition of the great vessels. Drugs such as alprostadil, a PGE-1 analog, can be used to keep a PDA open until the primary defect is corrected surgically.