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Medical Author:

John Mersch, MD, FAAP

John Mersch, MD, FAAP

Dr. Mersch received his Bachelor of Arts degree from the University of California, San Diego, and prior to entering the University Of Southern California School Of Medicine, was a graduate student (attaining PhD candidate status) in Experimental Pathology at USC. He attended internship and residency at Children's Hospital Los Angeles.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• What is a ventricular septal defect (VSD)?
• How common is a VSD?
• What is the normal design of the heart?
• How do VSDs cause problems?
• How is a VSD diagnosed? What are the symptoms of a VSD?
• What if the VSD is small?
• How is a small VSD treated?
• What if the VSD is large?
• How is a large VSD treated?
• What types of surgery are available to correct a VSD?
• What is the outlook (prognosis) after a VSD is repaired?
• What are complications of VSD surgery?
• What about unusual cases of VSD?
• What are long-term precautions with VSDs?
• Ventricular Septal Defect At A Glance
• Find a local Cardiologist in your town
• Ventricular Septal Defect Index

The pressure generated during contraction by the left ventricle is higher than that generated by the simultaneous contraction of the right ventricle. Blood will thus be pushed through the VSD (also called "shunted") from the left ventricle to the right ventricle. The right ventricle has to do extra work to handle the additional blood volume. It may have trouble keeping up with the load and enlarge, affecting its ability to pump efficiently. In addition, the lungs receive too much blood under too much pressure. The arterioles (small arteries) in the lungs thicken in response to the excess blood under excess pressure. If this extra pressure persists, permanent damage can be done to the lungs.

It makes a considerable difference whether the size of the VSD is small or large.

The diagnosis of a VSD is usually suspected clinically by hearing a characteristic heart murmur. A murmur is a sound generated by abnormally turbulent flow of blood through the heart. This murmur is the result of blood being shunted through the VSD from the higher-pressure left ventricle into the lower-pressure right ventricle. At birth, this pressure imbalance is minimal and does not usually develop until later in the first week of life. As such, it is rare for a doctor to hear the murmur of a VSD until the baby is a few days of age.

The evaluation of a child with a possible VSD is designed to confirm the diagnosis but also to check for other anatomical defects in the heart and to estimate the size of the shunt of blood from the left to right ventricle.

Such an evaluation usually begins with an electrocardiogram (EKG, sometimes also abbreviated ECG) and possibly a chest X-ray. A soundwave test of the heart (echocardiogram) is used to define the anatomy and evaluate the characteristics (amount and pressures) of the shunted blood. With the advent of superb echocardiography, the previously required cardiac catheterization is rarely necessary.