Patent ductus arteriosus overview
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Patent Ductus Arteriosus is a remnant of the distal sixth aortic arch and connects the pulmonary artery at the junction of the main pulmonary artery and the origin of the left pulmonary artery to the proximal descending aorta just after the origin of the left subclavian artery. Normally, the ductus closes within a few hours or days of birth; when it does not, the result is patent ductus arteriosus. This defect is common in premature infants but rare in full-term infants. Symptoms include shortness of breath and cardiac arrhythmia, and may progress to congestive heart failure if left uncorrected.
Patent ductus arteriosus is a heart condition that is normal but reverses soon after birth. In a persistent PDA, there is an irregular transmission of blood between two of the most important arteries (aorta and pulmonary artery) in close proximity to the heart. Although the ductus arteriosus normally seals off within a few days, in PDA, the newborn's ductus arteriosus does not close, but remains patent.
The pathophysiological consequences depend on the size of the defect and the pulmonary vascular resistance.
Epidemiology and Demographics
The PDA is commonly found in infants and constitutes only 2% of all congenital defects found in adults. The incidence is greater is in children who are born prematurely with history of perinatal asphyxia and infants with congenital rubella.
Like many congenital heart disease, the cause of patent ductus arteriosus is not clear. Clinical studies suggest that the genetic and environmental factors both play an important role during the pregnancy.
Natural History, Complications and Prognosis
The natural history of unoperated patients of patent ductus arteriosus depends on the amount of left to right shunting. The left to right shunting in turn depends on the size of ductus and the difference in resistance between the left and right side of heart. PDA can cause complications such as heart failure, infective endocarditis, rhythm disturbance, pulmonary hypertension and Eisenmenger syndrome.
Chest X Ray
Other Imaging Findings
Cardiac catheterization serves to establish the presence of a PDA by assessment of the increase of oxygen in the pulmonary artery. It also serves to identify the anatomy of the PDA, the severity of a left-to-right shunt, and the presence of pulmonary hypertension.
Prostaglandin E2 plays a key role in maintaining the patency of ductus arteriosus before birth. Thus, prostaglandin E2 inhibitors are used as a therapeutic options to close the patent ductus arteriosus.
Term and Older Children
In term infants and older patients, the Prostaglandin E2 inhibitors (indomethacin and ibuprofen) have not shown to be effective. This is so because the ductus in premature baby is different histologicaly from in older patients. As a result, pharmacologic therapy is only used routinely in preterm infants.
Infants without overt symptoms may simply be monitored as outpatients, while symptomatic PDA can be treated with both surgical and non-surgical methods.. Surgically, the ductus arteriosus may be closed by ligation, wherein the DA is manually tied shut, or with intravascular coils or plugs that leads to formation of a thrombus in the duct. Surgical ligation of the PDA can be accomplished with excellent results in uncomplicated patients. Recent experience with transcatheter closure has also been favorable, being today the procedure of choice for most patients. In certain cases it may be beneficial to the newborn to prevent closure of the ductus arteriosus. For example, in transposition of the great vessels, a PDA may prolong the child's life until surgical correction is possible. The ductus arteriosus can be induced to remain open by administering prostaglandin analogs.
The development of a fetal heart starts during the first trimester of pregnancy. Thus, many a times the fetal heart has already developed, by the time the female becomes aware of being pregnant. There are some risk factors that if avoided before and during pregnancy can decrease the occurrence of congenital heart diseases.
- Giuliani et al, Cardiology: Fundamentals and Practice, Second Edition, Mosby Year Book, Boston, 1991, pp. 1653-1663.
- Zahaka, KG and Patel, CR. "Congenital defects.'" Fanaroff, AA and Martin, RJ (eds.). Neonatal-perinatal medicine: Diseases of the fetus and infant. 7th ed. (2002):1120-1139. St. Louis: Mosby.