Hello and welcome to the Zero to Finals podcast. My name is Tom and in this episode I'm going to be

talking to you about patent ductus arteriosis. And you can find written notes on this topic at

zero definals.com slash PDA or in the cardiology section of the Zero to Finals Pediatrics book. So let's get straight into it.

The ductus arteriosis normally stops functioning within one to three days of birth and closes completely

within the first two to three weeks of life. When it fails to close, this is called a patent

ductus arteriosis or a PDA.

The reasons why it fails to close are unclear, but it may be genetic or it may be related to maternal infections such as rebella.

Prematurity is also a key risk factor.

A small PDA can be asymptomatic,

cause no functional problems and close spontaneously.

Occasionally patients can remain asymptomatic with a PDA throughout childhood

and presenting adulthood with signs of heart failure.

Let's talk about the path of physiology.

The pressure in the aorta is higher than that in the pulmonary vessels, so blood flows from the aorta into the pulmonary artery across a patent

ductus arteriosis. This creates a left to right shunt where blood from the left side of the heart

crosses to the right-sided

circulation and the lungs. This increases the pressure in the pulmonary vessels and causes

pulmonary hypertension, leading to right-sided heart strain as the right ventricle struggles to

contract against the increased pressure in the pulmonary vessels.

Pulmonary hypertension and right heart strain lead to right ventricular hypertrophy.

The increased blood that flows through the pulmonary vessels and returns into the left side of the heart also leads to left ventricular hypertrophy. So how does it present? A patent ductus

arteriosis can be picked up during the newborn examination if a murmur is heard. It may also

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