If your child has been diagnosed with a small ventricular septal defect (VSD), we want to help you understand about the condition and how it will impact on your child's life. 

What is a normal heart?

The heart is a muscular pump that has four chambers – two collecting chambers at the top (the atria) and two pumping chambers at the bottom (the ventricles). 

Between the atria and ventricles there is a wall, (septum), separating the left and right side of the heart. This stops oxygenated (red) blood mixing with deoxygenated (blue) blood. 

Normal circulation

Deoxygenated (blue) blood returning from the body goes into the top right chamber (atrium) of the heart. The blood then flows into the right ventricle and is pushed towards the lungs via the pulmonary artery to pick up oxygen. 

The oxygenated (red) blood from the lungs returns to the top left chamber (atrium), and then flows through the mitral valve into the left ventricle. As the heart pumps, the red blood is then forced into the aorta and pumped around the body.  

What is a ventricular septal defect? 

A VSD is a hole in the septum between the two lower chambers of the heart (the ventricles) that allows red (oxygenated) blood and blue (deoxygenated) blood to flow through. 

This means that the lungs receive extra blood, causing the lungs and heart to work harder.  

VSDs are the most common congenital heart defects seen in the UK; around 20 per cent of babies born each year are diagnosed with one (Congenital Heart Defects (CHD) UK, 2015). 

The term congenital means the condition has developed in the womb and is present at birth.

VSDs are classified by the size, location and number of defects. They can be small, moderate or large. Your child can have more than one VSD, and the hole may be anywhere along the ventricular septal wall.

There are two main types of VSD:

• muscular – found in the lower part of the septum - these holes are surrounded by muscle and most close on their own in childhood 
• perimembranous – located near the heart valves - these VSD sometimes close spontaneously

Your child’s cardiologist will confirm which type your child has.  

As a small VSD only allows a small amount of extra blood to flow between the ventricles, the heart and lungs don't have to work any harder. 

Patients with a small VSD do not have any symptoms and do not require any treatment. 

Small VSDs have a high chance of closing by themselves. Around 70 per cent will get smaller as your baby grows, and this can take between a few months and 25 years.

Most VSDs occur by chance, with no clear reason for their development.

How is the condition diagnosed and managed?

A small VSD is diagnosed by a murmur (a noise heard with a stethoscope), usually found shortly after birth or at your baby's six-week check. 

Your baby will then be referred to a cardiologist at Royal Brompton Hospital or to one of our outreach cardiology clinics in your local area. 

An echocardiogram will confirm if a VSD is present. 

In the clinic you will have the opportunity to meet one of the clinical nurse specialists (CNS) in children's cardiac care. The nurses help you understand your child's diagnosis, and offer further information and support. 

You will be able to contact your CNS if you have any worries or questions when you are at home. 

If your child is very young, the CNS will ask that your baby is weighed once or twice a month so we can make sure they are growing and gaining weight. This can be arranged with your health visitor.

Your child is not expected to need any treatment for this condition but will require follow-up appointments with their cardiologist.