A blood vessel known as the ductus arteriosus, or DA, connects two main arteries in the fetus, allowing most of the blood to bypass the lungs, which are fluid filled and inactive. After birth, the DA and other similar vessels would normally close, facilitating important circulatory changes. Patent ductus arteriosus, or PDA, is a developmental condition in which the DA fails to close after birth, leading to cardiovascular and respiratory problems.
Closure of the Ductus Arteriosus
When the newborn baby takes its first breath and the vessels in the lungs fill with blood, the DA is stimulated to constrict rapidly over 24 hours, eventually closing completely, typically after the first three weeks of life. Failure of the DA to close correctly is especially common in premature babies, and is characterized by the irregular transmission of blood between the key blood vessels around the heart known as the pulmonary vein and aortic arch, according to a December 2009 article published on Medline Plus.
Symptoms
Symptoms of PDA include rapid heart beat, shortness of breath, heart murmur and enlarged heart. Newborn babies with PDA usually have low blood oxygen levels, referred to as hypoxia, as less blood oxygenation occurs in the lungs, according to the website About Kids Health.
Complications
Although a small PDA may not cause significant problems throughout a person's life, a larger DA may cause severe complications if left untreated. Severe PDA often results in a large amount of blood from the left-hand side of the heart being pumped into the lungs, increasing blood pressure in the lungs considerably, potentially causing lung damage. PDA can cause a weakening in the heart muscle, leading to heart failure in severe cases. The body often compensates for PDA-induced structural heart weakness by increasing the size of the heart, which in turn can cause irregular heart rhythms, according to the National Heart Lung and Blood Institute.
Diagnosis
Noninvasive methods are predominantly used for diagnosis of PDA, including echocardiography, in which the motion of the heart is determined by measuring sound waves, and electrocardiogram, whereby the electrical activity of the heart is measured and used to understand the way the heart is beating. Newborns with PDA often have a very small, underdeveloped heart, which can be visualized with a chest X-ray, according to a December 2009 article published on MayoClinic.com.
Treatment
Surgical or nonsurgical methods can be used to treat PDA, depending upon the size of the ductus arteriosus and the severity of the symptoms. The ductus arteriosus can be surgically tied shut or fitted with plugs or coils. Drugs such as indomethacin, which inhibits the production of signaling molecules called prostaglandins, have been shown to help close the PDA, and are frequently prescribed to treat newborns with PDA, according to a December 2009 article published in "Annals of Pediatric Cardiology."
References
- Medline Plus: Patent Ductus Arteriosus
- Mayo Clinic: Patent Ductus Arteriosus (PDA)
- "Annals of Pediatric Cardiology"; Role of Prophylactic Surgical Ligation of PDA in Extremely Low Birth Weight Infants; R. Mosalli et al.; December 2009
- About Kids Health: Patent Ductus Arteriosus (PDA)
- National Heart Lung and Blood Institute: Patent Ductus Arteriosus
