What is Patent Ductus Arteriosus
It is a congenital heart disease in which ductus arteriosus (a hole) fails to close after birth, causing the oxygenated blood flow from the aorta to the pulmonary artery and causing high pulmonary blood pressure.
Causes
Common in females M:F = 1:3. Probable etiological factors are:
• Maternal rubella in the first trimester.
• Birth at high-altitude.
• Prematurity.
Mechanism
During foetal life, ductus arteriosus connects pulmonary artery at its bifurcation to the descending
aorta just below the origin of left subclavian artery and permits blood flow from pulmonary
artery to aorta. After birth, within hours or days, it closes spontaneously and remains as ligamentum arteriosum.
In PDA, it allows blood to flow from aorta to pulmonary artery. Up to 50% of left ventricular
output may enter into pulmonary artery, because pressure in aorta is higher.
Clinical Features
Symptoms
• May be asymptomatic.
• Breathlessness on exertion.
• Palpitation, weakness and loss of appetite.
Signs
• Pulse—may be high volume.
• BP—wide pulse pressure.
• JVP—normal
In Precordium
Palpation
• Apex beat—thrusting or heaving in nature.
• Systolic thrill—present in pulmonary area.
Auscultation
• Continuous murmur in left 2nd and 3rd intercostal space, called machinery murmur like
‘train in a tunnel’.
Complications
• Pulmonary hypertension with reversal of shunt (Eisenmenger’s syndrome).
• CCF.
• Infective endocarditis.
• Arrhythmia (atrial fibrillation).
• Duct may rupture or calcify.
Investigations
• ECG.
• X-ray chest shows cardiomegaly.
• 2D and colour Doppler echocardiography.
• MRI or CMR .
• Cardiac catheterisation.
Treatment
• Majority of PDA are small and can be closed at cardiac catheterisation by using implantable
occlusive device.
• In large PDA—surgical closure
• Prophylaxis for infective endocarditis.
• In neonate (1–3 weeks old), indomethacin (0.2 mg/kg IV) or ibuprofen may be given to constrict
and close PDA by inhibiting prostaglandin E synthesis. It is not helpful in older children.
• If Eisenmenger’s syndrome develops, surgery is contraindicated
(see Eisenmenger’s syndrome).