Patent Ductus Arteriosus

Introduction

The ductus arteriosus is a normal structure in a fetus. It is a small vessel connecting the aorta and the pulmonary artery. Soon after birth it will close spontaneously. If it remains patent (patient ductus arteriosus, PDA), it becomes a congenital heart malformation. Because the arterial blood pressure in the lungs is normally lower than that in the systemic blood vessel, a PDA will allow blood from the aorta shunting to the pulmonary arteries. The haemodynamic effect of a PDA depends on the amount of blood shunting to the lungs, and hence will be determined by the size of the PDA.

Signs and Symptoms

Children with small PDA may remain asymptomatic. The most common presentation in these situations would be an incidental finding of a heart murmur during examination for other medical conditions or health checks.

A moderate or large PDA causes large amount of blood shunting to the lungs, resulting in heart failure and hypertension of lung blood vessels. The child may have symptoms of breathlessness, feeding difficulty and impaired growth depending on their age.

Diagnosis

Other than typical physical findings, the diagnosis of PDA can be made by 2-dimensional echocardiogram (ultrasound study of the heart and blood vessels), which is a non-invasive investigational modality readily available at the out-patient / day-patient settings.

Management

Medical treatment

Drugs will be prescribed to control symptoms if heart failure develops. Under special circumstances, for example in premature babies suffering from a significant PDA, trial of medication can be used to close it. However, medical closure is not applicable to full-term babies and children.

Interventional cardiac catheterization

Treatment of PDA is now mostly performed by transcatheter occlusion. The procedure is performed under general anaesthesia in the cardiac catheterization laboratory to deliver an occlusive device or occlusive coil(s) to the PDA through a catheter advanced from the vessels at the groin. It requires only two small stab wounds at the groin, and hence it is less traumatic than the surgical approach. The average length of hospital stay is three days. Patients will then be followed up at the out-patient clinic with interval chest X-ray and echocardiogram. Transcatheter occlusion, however, may not be suitable for some newborns or babies with small body size.

Surgical treatment

The standard surgical procedure requires a surgical incision wound over the left chest to expose the PDA for ligation. Patients will usually have to stay in the intensive care unit overnight for observation with a wound drain that can usually be removed the next day. The hospital stay will usually be slightly longer as compared with transcatheter approach, while the post-operative outpatient follow-up remains similar to that of transcatheter occlusion. Surgical approach is usually reserved for small babies not suitable for transcatheter occlusion.

Acknowledgement

Principal author: Dr Robin H S CHEN on behalf of Cardiology Team, HKCH
Initial posting: Mar 2024

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