Ventricular Septal Defect
Francisco Talavera, PharmD, PhD
Ventricular Septal Defect Overview
Ventricular septal defect is a hole in the wall between the right and left ventricles of the heart. This abnormality usually develops before birth and is found most often in infants.
- The ventricles are the 2 lower chambers of the heart. The wall between them is called the septum. A hole in the septum is called a septal defect.
- If the hole is located between the upper chambers or atria, it is called an atrial septal defect.
- Infants may be born with either or both types of defects. These conditions are commonly known as "holes in the heart."
Normally, unoxygenated blood from the body returns to the right half of the heart, that is the right atrium, then the right ventricle, which pumps the blood to the lungs to absorb oxygen. After leaving the lungs, the oxygenated blood returns to the left half of the heart, that is the left atrium, then the left ventricle, where it is pumped out to provide oxygen to all the tissues of the body.
- A ventricular septal defect can allow newly oxygenated blood to flow from the left ventricle, where the pressures are higher, to the right ventricle, where the pressures are lower, and mix with unoxygenated blood. The mixed blood in the right ventricle flows back or recirculates into the lungs. This means that the right and left ventricles are working harder, pumping a greater volume of blood than they normally would.
- Eventually, the left ventricle can work so hard that it starts to fail. It can no longer pump blood as well as it did. Blood returning to the heart from the blood vessels backs up into the lungs, causing pulmonary congestion, and further backup into the body, causing weight gain and fluid retention. Overall, this is called congestive heart failure.
- If the VSD is large and surgically uncorrected, pressure can build excessively in the lungs, called pulmonary hypertension. The higher the lung or pulmonary pressure, the greater the chance of blood flowing from the right ventricle to the left ventricle, backwards, causing unoxygenated blood to be pumped to the body and cyanosis (blue skin).
- The risk for these problems depends on the size of the hole in the septum and how well the infant’s lungs function.
The ventricular septal defect may not be heard with a stethoscope until several days after birth. This is because a newborn's circulatory system changes during the first week with drop in the lung or pulmonary pressure, creating the greater pressure differential between the 2 ventricles, thus greater left-to-right shunt and audible murmur.
Ventricular septal defects are the most common congenital heart defects in infants (that is, defects that a person is born with).
- The condition occurs in about 25% of all infants born with a heart defect.
- These defects are more common in premature infants.
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