What is Hypoplastic Left Heart Syndrome?

Hypoplastic Left Heart Syndrome (HLHS) is a serious and rare congenital heart condition. In this syndrome, the fetal heart does not develop normally, so the left ventricle is undersized and far too weak to pump blood to the body. Some children survive a few weeks with this condition, but without surgical intervention, heart failure is inevitable.

Often, hypoplastic left heart is diagnosed through routine sonograms. The tiny size of the left ventricle is a sure indication of the condition to most experienced radiologists. Diagnosis is confirmed through fetal echocardiogram, which is similar to a sonogram, but looks more specifically at the fetal heart. Early diagnosis is valuable to parents, though stressful, because it gives them the opportunity to make decisions about what type of care to pursue.

Just a few decades ago, many parents were told that their children with hypoplastic left ventricles could not survive. However, greater numbers of children are now surviving and living with this condition. Unless complications occur, a child with Hypoplastic Left Heart Syndrome can often enjoy many years of activity before additional interventions become necessary.

When parents are faced with a diagnosis of Hypoplastic Left Heart Syndrome, there are three options for treatment. The first is to do nothing, called compassionate care. Until recently, most cardiologists felt that compassionate care was truly the best choice for children with HLHS. Instead of putting the child through multiple surgeries, the child was simply allowed to die naturally. Cardiologists and parents who have chosen this option felt that letting children go without subjecting them to risky treatments gave dignity to their death and was easiest for all concerned, though heartbreaking.

However, improved survival rates of surgery have radically changed the opinion of many cardiologists, although the value of compassionate care is still hotly contested. The development of the Fontan surgery, a set of staged surgical procedures performed over 3-4 years, provides the second option for parents who do not want compassionate care. Though it alleviates the symptoms of HLHS, Fontan surgery cannot "fix" the heart. It merely buys time, as much as 30 years, before transplantation.

The Fontan surgery was initially performed as a single surgery, in which the inferior and superior vena cavae were connected through a tunnel built through the heart. The superior cava was then connected to the pulmonary arteries, which established passive blood flow to the lungs. The heart would then pump blood only to the body through the right ventricle, making the hypoplastic left ventricle no longer necessary.

Early survival of Fontan patients was not favorable. To increase survival, surgeons began to break up the steps of the surgery. In time, three steps became the preferred method. First, a shunt would be placed shortly after birth to help the heart. In about 3-4 months, the Glenn procedure would connect the superior vena cava to the pulmonary valve, and finally at 2-5 years, the Fontan procedure connected the inferior and superior vena cavae.

Many surgeons began replacing the intra-cardiac tunnel with an extra-cardiac shunt (ECC). Though some surgeons still prefer the traditional tunnel, the ECC is performed on a warm beating heart and has far fewer complications. It is becoming the preferred method for the Fontan procedure, as studies show it to be as effective as the tunnel.

Many parents wish to avoid the multiple surgeries and choose transplant instead. A successful heart transplant means relatively few limitations and total heart health. However, availability of hearts for transplantation is variable. Further, life expectancy is far lower than for those with the Fontan surgery.

With Fontan surgery, there is still the future possibility of transplantation when the heart fails. The solution to a failing transplanted heart is another transplantation. If the initial heart has been rejected, second transplants have an even lower success rate.

The decision of how to address hypoplastic left heart syndrome in a child is highly personal and should be well-informed. If fetal diagnosis is made, parents may have 20 weeks in which to find the best hospital, decide what the best surgical procedure is, and find support from other parents. Though hypoplastic left ventricle was once an unviable condition, improving survival rates give hope to all those who may be faced with this diagnosis and the difficult decision it engenders.