Heart defects begin in the early part of pregnancy when the heart is forming. Congenital heart defects can affect any of the different parts or functions of the heart. The heart is a muscle that pumps blood to the body. It is divided into four hollow parts called chambers. Two chambers are located on the right side of the heart, and two are on the left.
Blood goes from the heart to the lungs where it picks up oxygen.
The blood carrying oxygen, which appears bright red, goes back to the heart. The heart then pumps the oxygen-rich blood through the body by way of arteries. As the oxygen is used up by the body's tissues and organs, the blood becomes dark and returns by way of veins to the heart, where the process starts over again. Some babies and children with heart defects experience no symptoms. The heart defect may be diagnosed if the doctor hears an abnormal sound referred to as a murmur.