The problem
In a healthy heart, blood passes from the left atrium to the left ventricle, which pumps it out of the heart to circulate throughout the body. After passing through all the organs, it enters the heart again in the right atrium. Then it passes to the right ventricle, which pumps it out to circulate through the lungs.
In a child with VSD, there is a hole in the wall between the right and left ventricle. This enables blood to flow between the ventricles. Because pressure is higher in the left side of the heart, blood usually flows from left to right. This leads to an excess of blood in the right side of the heart and in the lungs. This can cause symptoms of congestive heart failure, including fatigue, low appetite and low weight gain, and difficulty breathing. VSD usually has more intense symptoms than ASD, so treatment, with drugs or surgery, is more likely to be necessary.
