Monthly Archives: Jan 2003

Ventricular Septal Defect – VSD

Ventricular Septal Defect VSD

What is a Ventricular Septal Defect?

Ventricular septal defects – also called VSD – are similar to ASD.

A VSD is a “hole” in the wall between the two lower chambers of the heart – the ventricles.

VSD may be small, medium-sized or large, and may be single or multiple. It may occur in different parts of the ventricular septum, and may sometimes be found along with other heart defects.

What happens when there is a VSD ?

The wall between ventricles is meant to separate blood passing through each. This is to prevent mixing of “impure” blood from the veins with “pure” blood going to the arteries. When the wall is “broken”, mixing occurs.

However, only “pure” blood flows from the left ventricle into the right; no flow is seen from the right ventricle into the left side across the VSD and so “impure” venous blood does not reach the arteries. This is because pressure in the left ventricle is much higher than the right, and fluids always flow from places of high to lower pressure.


Atrial Septal Defect – ASD

What is an Atrial Septal Defect ?

The two upper chambers of the heart are called the right and left atrium. They are separated by a “wall”, called the ATRIAL SEPTUM. Sometimes, this “wall” is not complete. There is a hole in it.

This hole is called an Atrial Septal Defect – or ASD, in short. ASD’s may be large or small, single or multiple. The heart may be otherwise normal, or there may be other defects too.

What happens when there is an ASD ?

In the normal heart, blood flowing in the right sided chambers (atrium and ventricle) is completely separated from the left sided chambers by the atrial septum. When there is a hole in this “wall”, blood from the left atrium flows through the hole into the right side.

You might well ask, “Why only from left to right ?”

That’s because the pressure of blood in the left atrium is higher than in the right, and as you know, any fluid, including blood, will flow from a place with high pressure to one with a lower pressure.

So what is the effect of this ?