What is HLHS?

Hypoplastic left heart syndrome is a rare congenital heart defect in which the left side of the heart is severely underdeveloped. The underdeveloped left side of the heart in hypoplastic left heart syndrome results in an inability to properly pump blood to the body. Immediately after birth, and for a few days, the right side of the heart compensates, pumping blood to the lungs and to the rest of the body. After a few days, the opening (patent ductus arteriosus) between the two sides of the heart closes, meaning that the right side of the heart can no longer pump blood out to the body.

Many babies who have hypoplastic left heart syndrome also have atrial septal defect, or a hole in the wall between the upper chambers of the heart. This defect allows the right side of the heart to pump blood to the body after the natural connection closes. If the baby does not have atrial septal defect or the natural connection closes, the baby can go into shock or die.


Hypoplastic left heart syndrome occurs during fetal development. The cause is unknown although genetics may play a role. If your family has a history of congenital heart defects, you may want to consider consulting with a genetic counselor, who may recommend genetic testing.


Babies who have this condition may seem normal at birth, but the condition quickly becomes noticeable within a few days of life as the opening between the right and left side of the heart begins to close. The baby then becomes ashen, has difficulty breathing and cannot eat because the heart is too small to supply blood, oxygen and nutrients to the body.


At Ohio State, we ensure that each patient receives individualized care for their congenital heart defect. By creating a care team to diagnose and treat each case, we can better understand what steps will help patients get back to living their lives.

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Hypoplastic left heart syndrome treatment

Babies born with hypoplastic left heart syndrome must have a series of surgeries to treat the heart defect or a heart transplant. The most common treatment is a series of three operations that are performed to reconfigure the cardiovascular system to create normal blood flow in and out of the heart. These surgeries do not correct the defect but relieve the symptoms without resulting in a cure. Lifelong care is necessary after surgery.


If surgery is not immediately possible, medication can help to manage the condition. Prostaglandin, a medication that dilates the blood vessels, may be recommended before a baby is ready for surgery to keep the ductus arteriosus open and maintain adequate blood supply to the body.

Nonsurgical procedures

A cardiac catheterization procedure called atrial septostomy can enlarge the connection between the heart’s upper chambers and improve oxygen delivery throughout the body.

Hypoplastic left heart syndrome surgery

There are several surgeries that treat hypoplastic left heart syndrome and in some complex cases a heart transplant may be necessary.

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