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Single Ventricle Defects

What are Single Ventricle Defects?

A single ventricle defect, also known as single ventricle lesions or anomalies, is a rare congenital (present at birth) heart disorder that causes one of the two pumping chambers (ventricles) of the heart to be too weak to work correctly, or the chamber might be missing a valve.

In a healthy heart, the ventricles pump the blood to and from the lungs to pick up oxygen. It is then sent out to the rest of the body and back again to start the process over. In a single ventricle defect, the oxygen levels in the blood will drop and the heart must work harder, which can lead to muscle weakness. A child’s oxygen levels will vary, depending on the type and severity of defect, and will typically require medical attention shortly after birth.

What are the different types of Single Ventricle Defects?

Hypoplastic left heart syndrome (HLHS)

The left side of the heart (the aorta and ventricle) is too small, and the naturally occurring holes in the artery and heart walls did not properly close or develop.

Pulmonary atresia/intact ventricular septum

The pulmonary valve did not form during development, but the heart wall between the lower chambers is intact. Blood flows between the holes, rather than through normal circulation.

Tricuspid atresia

The tricuspid valve did not form during development. This valve controls the flow back into the heart when the blood is returning to pick up oxygen.

What are the signs and symptoms of Single Ventricle Defects?

Most children with single ventricle defects show symptoms at birth or shortly after. Symptoms include:

  • Cyanosis (bluish discoloration of the skin, fingernails and mouth due to lack of oxygen)
  • Shortness of breath (dyspnea)
  • Fast breathing or breathlessness
  • Poor feeding
  • Lack of energy, sluggish, drowsy (lethargy)
  • Weak pulse
  • Pounding heart