What is HLHS?

Hypoplastic Left Heart Syndrome, or HLHS, is a Congenital Heart Defect (CHD) where the left side of the heart does not form properly. It is a rare and severe CHD only affecting roughly 1% of children with a CHD. Effectively children with HLHS have only the right side of their heart functioning. This side of the heart, in a normal heart, takes blood in from the body and pumps it to the lungs. The left side of the heart takes the blood from the lungs and pumps it back out to the body. Without the left side, the heart cannot pump blood to the body and the body's organs rapidly become oxygen starved. Until recently children born with HLHS did not survive longer than a week after birth.

Over the last three decades a course of three surgeries was developed that allowed the heart to be reshaped in order to allow the right side of the heart to act as the whole heart. The first surgery, the Norwood procedure, is performed within the first week of life. The second surgery, the Glenn procedure, is performed around 3 months of age. The final surgery, the Fontan procedure, is performed around 3 years of age. While these procedures have allowed children to live into adulthood, there is no certainty as to how long the heart will continue to function or if there will be degradation over time.

Instead of having the surgical procedures performed some children may receive a heart transplant. This is rare, as donor hearts are not common and donor rejection rates are the same in children as they are in adults. The sad truth is that even if a child receives a heart transplant instead of getting the heart surgeries and the transplant is not rejected, they still face many potential medical struggles.

Why is research important?

Recent years have seen amazing work in the area of surgical re-working of the heart in order to give children the best chance to make it into adulthood. But that heart growing into adulthood and beyond is an uncharted territory. No good data exists to show how a single ventricle heart will function over the lifetime of an individual. The question: "How long can half a heart do the work of a whole heart?" hasn't been answered yet. We want the answer to be: as long as you need it to! But if that isn't the answer we get, then research into solutions for these unknowns is necessary to ensure that people with HLHS can lead full lives.

What is a CHD?

Congenital Heart Defects, or CHD, are birth defects that occur in the heart. They can take many forms from simple size issues in the heart valves, to holes in the heart chamber walls, to conditions like HLHS where entire portions of the heart remain unformed or misformed at birth.

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