Patent Ductus Arteriosus

Patent ductus arteriosus (PDA) is a congenital disorder in the heart wherein a neonate’s ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain. With age, the PDA may lead to congestive heart failure if left uncorrected. The ductus arteriosus is a normal fetal blood vessel that closes soon after birth. In a PDA, the vessel does not close and remains “patent” (open) resulting in irregular transmission of blood between two of the most important arteries close to the heart, the aorta and the pulmonary artery. PDA is common in neonates with persistent respiratory problems such as hypoxia, and has a high occurrence in premature children. In hypoxic newborns, too little oxygen reaches the lungs to produce sufficient levels of bradykinin and subsequent closing of the DA. Premature children are more likely to be hypoxic and thus have PDA because of their underdeveloped heart and lungs.

Ductus Arteriosus

Remnant of sixth aortic arch

Joins origin of left PA to aorta just distal to left subclavian artery.

In foetus it allows RV blood to bybass the unaerated lung; normally closes within 48 hours of birth to be known as ligamentum arteriosum.

Maternal rubella may cause its persistence

History of Patent Ductus Arteriosus 

Females                –        > Males, often familial

Infants                  –        Congestive heart failure

Small shunts          –        asymptomatic

Large shunts          –        dyspnoea, Congestive Heart Failure (CHF)

Eisenmenger syndrome with cyanosis of lower limbs (differential cyanosis)

Leg fatigue rather than dyspnoea

Diagnosis of Patent Ductus Arteriosus

PDA is usually diagnosed using non-invasive techniques. Echocardiography, in which sound waves are used to capture the motion of the heart, and associated Doppler studies are the primary methods of detecting PDA. Electrocardiography (ECG), in which electrodes are used to record the electrical activity of the heart, is not particularly helpful as there are no specific rhythms or ECG patterns which can be used to detect PDA.
A chest X-ray may be taken, which reveals the overall size of neonate’s heart (as a reflection of the combined mass of the cardiac chambers) and the appearance of the blood flow to the lungs. A small PDA most often shows a normal sized heart and normal blood flow to the lungs. A large PDA generally shows an enlarged cardiac silhouette and increased blood flow to the lungs

Physical Examination findings in Patent Ductus Arteriosus 

Wide pulse pressure with hyperdynamic apex

Systolic thrill upper left sternal border

Loud continuous machinery murmur in 2^nd left intercostals space, radiating to left shoulder, often accompanied by thrill.

Mitral diastolic flow murmur.

With onset of pulmonary hypertension, the diastolic component of machinery murmur shortens.

X-Ray findings in Patent Ductus Arteriosus 

Pulmanory plethora

Enlarged Left Atrium and Left Ventricle

Dilated aorta and pulmonary artery

E.C.G findings

Volume coverload of LV

Left artrial enlargement

Echo findings

Doppler-turbulence / gradient in LPA

Enlargement of LA and LV

Dilated aortic root.

Treatment for Patent Ductus Arteriosus 

Indomethacin 0.2 mg / kg IV in preterm infants to facilitates duct closure

Transfemoral plug closure if thoracotomy to be avoided

Adult with small shunts only need bacterial endocarditis prophylaxis. Large shunts-sugical closure.

More recently, PDAs can be closed by percutaneous interventional method.Via the femoral vein or femoral artery, a platinum coil can be deployed via a catheter, which induces thrombosis (coil embolization). Alternatively, a PDA occluder device (AGA Medical), composed of nitinol mesh, is deployed from the pulmonary artery through the PDA. The larger skirt of the device sits on the aortic side while the ampulla of the device hugs the walls of the PDA, with care taken to avoid occlusion of the pulmonary arterial lumen by the device. These methods permit closure without open heart surgery.