Patent Ductus Arteriosus

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Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Management

Patent Ductus Arteriosus (PDA) is a heart condition that occurs when the ductus arteriosus, a blood vessel in an infant's heart, does not close properly following birth. The ductus arteriosus connects the two major arteries in the heart, the pulmonary artery and the aorta. This allows blood to bypass the foetal lungs. In PDA, this vessel remains open after birth, resulting in abnormal blood flow between the arteries and adding stress to the heart and lungs.

• Genetic factors

• Premature birth: premature infants, especially those born before 37th week of pregnancy, have an increased likelihood of developing PDA. In full-term infants, the ductus arteriosus is more likely to close on its own.

• Low birth weight: Infants with a low birth weight are also at a greater risk of developing PDA.

• Other factors: Infections such as rubella during pregnancy can increase the risk of PDA and other congenital heart defects. Also, diabetes and certain medications taken by the mother during pregnancy may increase the risk of PDA in infants.

• Gender: PDA is more prevalent in female infants than in male infants.

The ductus arteriosus is a momentary blood vessel that connects the pulmonary artery (which transports blood from the heart to the lungs) to the aorta in a normal heart.  The ductus arteriosus allows blood to skip the lungs before birth because the foetus receives oxygen from the placenta. The lungs take over oxygenation shortly after birth, and the ductus arteriosus usually closes within the first couple of days of life.

Patent Ductus Arteriosus (PDA) is a condition in which the ductus arteriosus fails to close, culminating in an unusual link between the aorta and pulmonary artery. This results in the backflow of o2-rich blood from the aorta into to the pulmonary artery, resulting in multiple physiological effects:

The mixing of o2-rich blood from the aorta with o2-poor blood in the pulmonary artery results in higher blood flow to the lungs. This raises the lung burden and may result in pulmonary edema and breathing difficulties.

As even more blood rushes into the pulmonary artery, the heart has to beat more vigorously to try and force the blood from the lungs and back to the heart. Over time, this causes the left ventricle to work harder, leading to enlargement and increased possibility of heart failure.

• Premature birth

• Low birth weight

• Family history

• Genetic syndromes: such as Down syndrome

• Maternal factors: diabetes or poorly controlled blood sugar during pregnancy.

• Some infections during pregnancy:

• Female gender

Symptoms differ based on the size of the ductus arteriosus; in general, a small child is asymptomatic. Major signs may include the following:

• Tachypnea or respiratory distress (SOB)

• Particularly during feeding or activity, fatigue

• Failure to thrive

• Perfused sweating, particularly during feedings

• Tachycardia

• Cyanosis (bluish skin, lips, and nails) is the result of decreased oxygen delivery to the body's tissues.

• A heart murmur detected during a physical examination

• Physical examination.

• Electrocardiogram (ECG).

• Echocardiogram (main diagnostic investigation)

• Cardiac magnetic resonance imaging (CMR).

• CXR (large pulmonary artery may be seen)

Watchful waiting: if asymptomatic, the current recommendation is to wait until 1 year of age with regular evaluations and checkups to ensure that the PDA has closed.

Catheter-based closure: If the PDA fails to close on its own or causes severe symptoms, a minimally invasive procedure involving a catheter may be performed. Under X-ray guidance, a small tube is inserted into a blood vessel, typically in the groyne, and guided to the heart. The ductus arteriosus is then sealed using a device, such as a coil or an occluder. This procedure is less invasive and has a shorter recovery period than surgery.

Surgery: If catheter-based closure is impossible or ineffective, open-heart surgery may be required to close the PDA.

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