Congenital Heart Defects: Understanding Ventricular Septal Defects

Ventricular Septal Defect (VSD) is one of the most common types of congenital heart conditions. The heart consists of two main chambers called ventricles—the left and the right. The left ventricle is responsible for pumping oxygen-rich blood into the aorta, which distributes it throughout the body. Meanwhile, the right ventricle transports oxygen-poor blood to the lungs via the pulmonary artery for oxygenation.

What Happens in a Normal Heart?

In a healthy heart, the ventricular septum—a muscular wall—separates the left and right ventricles completely. This separation ensures that oxygenated and deoxygenated blood do not mix, allowing the circulatory system to function efficiently.

What Is a Ventricular Septal Defect?

A Ventricular Septal Defect occurs when there is an abnormal opening or hole in the septum that divides the two ventricles. This condition is a type of birth defect that develops during the early stages of fetal growth. Normally, the septum forms as two parts—the membranous portion and the muscular portion—grow toward each other and fuse together to close the gap between the ventricles.

Why Does a VSD Develop?

When this fusion process is incomplete or disrupted, a hole remains, resulting in a VSD. This defect allows blood to flow abnormally between the ventricles, typically from the left to the right side due to higher pressure in the left ventricle. This extra blood flow can strain the heart and lungs, leading to various health complications if left untreated.

When Does VSD Form During Fetal Development?

The formation of the heart begins in the first trimester of pregnancy, within the first 12 weeks. During this critical period, any disruption in the development of the septum can lead to a VSD. Factors such as genetic abnormalities or environmental influences may contribute to this developmental issue, although in many cases the exact cause remains unknown.