Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome, or HLHS for short, means that the whole left side of the heart did not develop normally. Therefore, the mitral and aortic valves are tiny or absent, as are the the left ventricle and the first part of the aorta.

HLHS is not a survivable lesion without major open heart surgery. There are two options, one is cardiac transplantation, in which the entire heart is replaced by a donated heart, and the other is called staged palliation, which is explained below. Your doctor should advise you about the risks and benefits to each of these two options.

For HLHS, staged palliation involves three operations. In order, these are the Norwood operation, bidirectional Glenn operation, and the Fontan operation. The Norwood operation is done very soon after birth, and converts the right ventricle into the main, or systemic ventricle. The bidirectional Glenn operation is done next, and diverts half of the blood returning from the body to the lungs. It is typically done at about six months of age. The Fontan operation is the last stage of the staged palliation, and diverts all of the blood returning from the body to the lungs. It is typically done around 2 years of age. The timing of these operations is variable, and depends on many clinical and social factors.

Staged palliation for HLHS is one of the great achievements of congenital heart surgery in the 90's. In what used to be a uniformly fatal disease, consider the following: Survival following a Norwood operation is around 80%, following a bidirectional Glenn operation around 100%, and following a Fontan operation around 95%. Overall, survival at 5 years of age is around 70 - 75%. Most patients who get through the three stages do quite well: Very few are on medications, almost all have normal growth and development, and very few have any exercise or other kinds of limitations.

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