Hypoplastic Left Heart Syndrome: Overview

What is hypoplastic left heart syndrome?

Children with hypoplastic left heart syndrome have a small, underdeveloped left side of the heart. This may involve all or some parts of the left heart including the aorta, aortic valve, left ventricle and mitral valve. The left side of the heart is so underdeveloped that it cannot pump enough blood to the body.

Hypoplastic left heart syndrome is a congenital heart condition, meaning kids are born with the disease. With this condition, the only way for blood to get to the body is if it can pass backwards through the heart from the left atrium to the right atrium and ventricle, then through the pulmonary artery and through a small hole called the ductus arteriosus that connects to the aorta.

The ductus arteriosus is one of the heart structures that allow a baby's heart to function in the womb. The ductus arteriosus normally starts to close very soon after birth. Children with hypoplastic left heart syndrome need medication to keep the ductus arteriosus open in order to survive.

Who gets hypoplastic left heart syndrome?

Hypoplastic left heart syndrome is more common in boys than girls, although the reason is not known. About 8% of kids with congenital heart conditions have hypoplastic left heart syndrome.

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