ventricular septal defect

ventricular septal defect

Figure A shows the normal anatomy and blood flow of the interior of the heart. Figure B shows two common locations of ventricular septal defects. The defect allows oxygen-rich blood from the left ventricle to mix with oxygen-poor blood in the right ventricle.

Ventricular septal defect (VSD) is a hole (defect) in the wall that separates the lower chambers of the heart. The lower chambers of the heart are called the ventricles. The wall between them is called the ventricular septum. In the normal heart, the septum prevents blood from flowing directly from one ventricle to the other. In a heart with a VSD, blood can flow directly between the two ventricles.


VSD is a congenital heart defect, which means that it is present at birth. In children with a VSD, blood usually flows through the defect from the left ventricle to the right ventricle. This causes extra blood (called volume overload) in the pulmonary arteries and lungs, and in the left atrium and left ventricle.


Effects of VSD

Over time, a VSD that does not close – especially a large VSD – can cause:


  • Congestive heart failure. Infants with large VSDs may develop congestive heart failure. Extra blood flows from the left ventricle through the right ventricle to the lungs and back to the left atrium and on to the left ventricle. This causes the left atrium and left ventricle to handle an increased amount of blood, and the workload on the heart increases. The increased workload on the heart also increases the heart rate and the body's demand for energy. The extra blood flow in the lungs may cause rapid breathing, while also increasing the body's demand for energy.

  • Growth failure, especially in infancy. Your baby may not be able to eat enough to keep up with his or her body's increased energy demands. Your baby may lose weight or fail to grow and develop as he or she should.

  • Bacterial endocarditis is an infection of the lining of the heart, valves, or arteries. Endocarditis often occurs following dental and medical procedures.

  • Irregular heartbeat or rhythm (arrhythmia). The extra blood flowing into the left atrium can cause the atrium to stretch and enlarge. When this occurs, your child can develop a fast heartbeat with symptoms such as dizziness or fainting.

  • Pulmonary arterial hypertension (high blood pressure in the pulmonary arteries). If a moderate or large VSD is not closed, sustained blood flow under higher pressure into the pulmonary arteries causes the arteries to become thickened and stiff. The amount of blood flow to the lungs decreases over time as the resistance to blood flow into the pulmonary arteries increases. However, this causes the right ventricle to work harder. Today, pulmonary artery hypertension rarely develops because most large or moderate VSDs are closed in infancy or early childhood.


    VSD is the most common type of congenital heart defect. Infants born with a VSD may have a single hole or more than one hole in the wall that separates the two ventricles. The defect may also occur by itself or with other congenital heart defects.



    Doctors classify VSDs based on the:


  • Size of the defect.
  • Location of the defect.
  • Number of defects.
  • Presence or absence of a ventricular septal aneurysm – a thin flap of tissue on the septum. It is harmless and can help a VSD close on its own.

    VSDs range in size from small to large.


  • Small VSDs usually allow only a small amount of blood flow between the ventricles. Because of this, they are sometimes called restrictive. Most small VSDs:
          - Do not cause symptoms in infants and children
          - Close on their own, often by school age
          - Rarely need surgery or other procedures to close the defect

  • Moderate (or medium-sized) VSDs are less likely than small defects to close on their own. They may require surgery to close and may cause symptoms during infancy and childhood.

  • Large VSDs allow a large amount of blood to flow from the left ventricle to the right ventricle and are sometimes called nonrestrictive. A large VSD is less likely to close completely on its own, but it may get smaller. A large VSD can cause more symptoms in infants and children, and surgery is usually needed to close it.

    VSDs are found in different parts of the septum.


  • Membranous VSDs are located near the heart valves. They can close at any time if a ventricular septal aneurysm is present.
  • Muscular VSDs are found in the lower part of the septum. They are surrounded by muscle, and most close on their own during early childhood.
  • Inlet VSDs are located close to where blood enters the heart. They are less common than membranous and muscular VSDs.
  • Outlet VSDs are found in the part of the ventricle where the blood leaves the heart. This is the rarest type of VSD.


    Most VSDs close on their own or are so small that they don't need treatment. Some children and adults need surgery or other procedures to close the VSD, especially if it is large. Most children and adults live long and productive lives after their VSD closes or is repaired.