Patent Ductus Arteriosus Definition
Patent ductus arteriosus (PDA) is a congenital heart disorder in which the ductus arteriosus of a neonate remains open or ‘patent’ after birth. The ductus arteriosus is an essential part of the circulatory system, prior to birth. It generally closes shortly after a baby is born. In some cases, however, it remains open – thereby leading to impaired transmission of blood among the two most important arteries that are close to heart, the pulmonary artery and the aorta.
PDA can give rise to serious, life-threatening complications like hypoxia and congestive heart failure.
Patent Ductus Arteriosus Causes
During the developmental stage of a baby in the womb of its mother, the vascular connection known as ductus arteriosus is a necessary and normal part of blood circulatory system. It helps to divert the blood from the fetal lungs while they are not being used. Oxygen is supplied to the fetus from the blood circulating within the body of the mother. It is normal for the ductus arteriosus to close within 2 or 3 days after birth just as the newborn’s heart adjusts to life outside womb. In premature infants, this connection frequently takes longer to get closed on its own. An open connection leads to the development of PDA. This abnormal opening leads to the circulation of a surplus amount of blood within the lungs and heart.
The exact causes of PDA are not known. Several environmental factors and genetics are supposed to play a role. Babies having Down syndrome or neonatal respiratory distress syndrome as well as babies of mothers who were affected by rubella or German measles during their pregnancies have been known to be affected by this disorder. The rubella virus traverses the placenta and then spreads through a baby’s circulatory system thereby damaging the organs and the blood vessels. Babies born at altitudes higher than 10000 feet are also at a higher risk of developing this condition. The other factors which might lead to PDA include Hypoplastic left heart syndrome, pulmonary stenosis and transposition of great vessels.
Patent Ductus Arteriosus Pathophysiology
The ductus arteriosus is generally patent or open during one’s fetal life. This vessel is an important bodily structure associated with the fetal development as it significantly contributes to flow of blood throughout rest of the organs and structure. The ductus handles most of the responsibilities of right ventricular outflow, contributing to 60% of total cardiac output during the entire fetal life. Only around 5% to 10% of its outflow traverses through the lungs.
The patency is endorsed by the continual production of PEG2 or prostaglandin E2 by the ductus. If the ductus closes before birth, it might result in right heart failure. Fetal closure of ductus arteriosus or prostaglandin antagonism can be caused by the use of nonsteroidal anti-inflammatory medications (NSAIDs) by the mother.
PDA gives rise to a left-to-right shunt, and allows the blood to move from systemic circulation to pulmonary circulation. Hence, there is an excess pulmonary blood flow. Decreased pulmonary compliance gives rise to pulmonary engorgement. This increased blood flow produces an unpredictable reaction from the pulmonary vasculature.
The magnitude of excess pulmonary blood flow rests on a limited number of factors. The larger the inner diameter of most narrow ductus part is, the larger is the left-to-right shunt. In case the ductus arteriosus is constricted, the total length of narrowed area also influences the size of the shunt. A longer ductus arteriosus is commonly associated with a rather smaller shunt.
Patent Ductus Arteriosus in Adults
Although PDAs are normally seen in children, they can also be found in adults. If a PDA is left untreated during early life, it can develop to a significantly noticeable size when the patient grows up. However, most adult cases of PDA are quite small to moderate. It is uncommon to find a large-sized PDA in an adult. The symptoms of an untreated PDA include heart palpitations and shortness of breath.
Patent Ductus Arteriosus Symptoms
Although there are cases where PDA is asymptomatic, the common instances of this condition are associated with certain characteristic symptoms. These include:
- Poor growth
- Bounding pulse
- Heavy sweating
- Loss of appetite
- Poor weight gain
- Differential cyanosis
- Respiratory problems
- Left subclavicular thrill
- Widened pulse pressure
- A dusky or bluish skin tone
- Lack of energy or tiring easily
- Dyspnea or shortness of breath
- Enlarged heart or cardiomegaly
- Heart murmur that runs continuously like a machine
PDA patients generally present themselves in good health, and display normal heart rate and respirations. If the ductus arteriosus is large or moderate, bounding peripheral pulses and widened pulse pressure are frequently present. This indicates increased volume of left ventricular stroke and diastolic blood runoff into initially low-resistant pulmonary vascular bed. There can also be prominent carotid and suprasternal pulsations secondary to an increased volume of left ventricular stroke.
Patent Ductus Arteriosus Diagnosis
While diagnosing PDA, a doctor would try to see if a baby has any heart murmur or is having any signs of abnormal heartbeat. The sounds of murmur can be detected through a stethoscope. In case a doctor hears heart murmur sounds or notices any signs of heart defects, he or she may recommend the following tests:
- CT scans
- MRI scans
- Chest X-rays
- Doppler studies
- Cardiac catheterization
- Electrocardiogram (ECG)
A normal heart size and normal flow of blood to the lungs indicates a small PDA, whereas an enlarged cardiac structure and an increased flow of blood to the lungs generally points to a large PDA.
Patent Ductus Arteriosus Differential Diagnosis
A great number of conditions show signs and symptoms similar to that of a PDA. Hence, it is necessary to diagnose PDA accurately in order to ensure that appropriate medical care is administered to a baby. The differential diagnoses for PDA includes ensuring the absence of conditions such as:
- Venous hum
- Acute anemia
- Acute Pericarditis
- Cardiogenic shock
- Sickle Cell Anemia
- Aortic regurgitation
- Mitral regurgitation
- Coarctation of aorta
- Cervical venous hum
- Pediatric Tachycardia
- Coronary Artery Fistula
- Dilated cardiomyopathy
- Pulmonic Valvular Stenosis
- Persistent truncus arteriosus
- Systemic arteriovenous fistula
- Atrioventricular malformation
- Aortopulmonary Septal Defect
- Pulmonary arteriovenous fistula
- Bronchial pulmonary artery stenosis
- Absence pulmonary valve syndrome
- Pediatric Sinus of Valsalva Aneurysm
- Peripheral pulmonary artery stenosis
- Ruptured sinus of fistula and valsalva
- Total anomalous pulmonary venous return
- Pediatric Acute Respiratory Distress Syndrome
- Ventricular septal defect with aortic regurgitation
- Aortopulmonary fenestration (Aortopulmonary window)
- Pediatric tetralogy of Fallot accompanied by absent pulmonary valve
Patent Ductus Arteriosus Treatment
PDA can get closed on its own in newborns without medical intervention. Hence, a physician may choose to wait and watch, giving the condition time to mend itself if management of heart failure can be carried out easily. If the symptoms are severe or if additional complications are anticipated, immediate medical attention along with surgical repair might be required.
If the presence of a PDA extends beyond the stage of the newborn period, the condition would normally not close by itself. Closure is advised in such cases in order to prevent any future risk of Endocarditis.
NSAID medications like ibuprofen or indomethacin can be administered to newborns. These medications are applied to the stomach where it facilitates constriction of the muscles in the walls of patent ductus arteriosus and leads to a closure. Doctors need to check the lab values of newborn babies before recommending these medications. If the values are not normal or if these medications do not function properly, surgery needs to be performed to tie off the PDA. The medications are commonly successful only in newborns. In case of children and older infants, the PDA can be closed by surgery or by an alternative method which involves usage of a coil or device in a cardiac catheterization laboratory.
During a cardiac catheterization procedure, a patient is either put under general anesthesia or sedated and then catheters are positioned into the blood vessels in groin. These catheters are then placed in aorta close to ductus arteriosus, after which a picture (angiogram) is obtained to identify the size and shape of a ductus arteriosus. In case of a small ductus, a coil might be placed inside the vessel. However, if it is larger, then various types of plug-shaped gadgets can be used for occluding the vessel.
If surgery is employed to close a PDA, it is done by making a small incision between the ribs around the left side. The ductus arteriosus is then tied and cut. This procedure can be carried out at any stage and is especially recommended for cases involving a large PDA or any other unusual anatomy.
Patent Ductus Arteriosus Complications
Severe cases of PDA might lead to serious complications such as:
- Heart failure
- High blood pressure
- Pulmonary hypertension
- Eisenmenger’s syndrome
- Intraventricular hemorrhage that might eventually lead to serious brain damage
Patent Ductus Arteriosus Prognosis
A proper surgical procedure or medical intervention can cure the condition. Without proper treatment, however, PDA might progress to give rise to serious heart-related complications.
Patent Ductus Arteriosus Prevention
Evidence suggests that if appropriate doses of indomethacin are administered prophylactically on the 1st day of life to all the preterm infants, it can reduce the risk of PDA as well as the associated complications. It also reduces the need for a surgical treatment. However, there are no evidences to suggest that prophylactic doses of Indomethacin improve the rate of survival for PDA-affected infants or reduce the propensity of long-term disabilities such as:
- Cerebral palsy
- Hearing impairment
- Visual impairment
- Decreased cognitive performance
Patent Ductus Arteriosus Pictures
The pictures here would give you a clearer idea about this heart condition.
Picture 1 – Patent ductus arteriosus
Picture 2 – Patent ductus arteriosus Image
Patent ductus arteriosus might lead to severe complications of the heart if left untreated. The condition needs immediate medical attention for its optimal management.