Lagan's Foundation

What are the Different Types of Septal Defects?

Septal defects

A septal defect is a defect present at birth and can affect the structure of a baby’s heart and the way it works. 

With the correct diagnosis and treatment, infants with septal defects are living longer and healthier lives.

What are septal defects?

Septal defects are defects of the heart in which there is a hole in the walls that separate chambers. 

A hole can vary in size and close on its own or be closed with surgery; however, when left undiagnosed and untreated, it can cause problems in childhood and adulthood. 


What does septal mean?

Septal refers to the septal tissue that separates the heart’s right and left side. It consists of both ventricular and atrial septum’s.

A healthy septum helps the heart to pump blood efficiently by preventing it from flowing back into the heart chambers.

What are the types of septal defects in children?

There are two main types of septal defects that children may suffer from:


Atrial Septal Defects

An Atrial Septal Defect (ASD) occurs when there is a hole between the two collecting chambers of the heart, known as the left and right atria. When an ASD is present, extra blood flows through the defect to the right side of the heart which causes it to stretch and enlarge.


There are four main types of ASD:

  • Ostium Secundum Atrial Septal Defect – This is the most common type of ASD. It is caused when a part of the atrial septum fails to close completely while the heart is developing. 
  • Ostium Primum Atrial Septal Defect – This defect is part of atrioventricular canal defects and is associated with a split of the mitral valve. 
  • Sinus Venosus Atrial Septal Defect – This occurs in the superior vena cava and right atrium junction which causes the veins to drain into the right atrium instead of the left. 
  • Coronary Sinus Atrial Septal Defect – This defect is located in the wall of the coronary sinus where it passes behind the right atrium and carries the blood flow from the heart’s own vein back to the right atrium. This is the rarest of all ASDs. 


Ventricular Septal Defects

A Ventricular Septal Defect (VSD) is a common congenital heart defect, and it occurs when there is a hole between the two pumping chambers of the heart, known as the left and right ventricles. 

This means that extra blood flows between the hole from left to right due to the difference in pressure between them. The extra blood goes to the lungs, which causes high pressure in the lungs and stretches the left ventricle. 


What are the most common septal defects?

A Ventricular Septal Defect is the most common form of congenital septal defect, affecting 20% of babies who are born with septal defects. 

A small VSD is usually very minor and will not present itself with many, if any, symptoms. However, larger holes may need to be repaired to avoid permanent damage or complications.

How do septal defects occur?

Septal defects occur during pregnancy while the baby’s heart is still developing. The muscular wall that separates the heart into the left and right side doesn’t fully form, leaving one or multiple holes. The size of these holes can vary. 

There are often no clear causes for septal defects. Genetic and environmental factors may play a role, such as the health of the mother. Septal defects can also occur with other heart defects at birth.