A: Hypoplastic Left Heart Syndrome (HLHS) is a condition in which the left side of the heart is underdeveloped. Usually, the left ventricle, the left atrium, the mitral valve and the aorta are affected. It is called a syndrome because it can encompass several different variations and varying degrees of development of these parts of the heart.
To understand HLHS, it is helpful to understand how a normal baby's heart works. The heart is comprised of four chambers: the upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles.
Very simply, in a healthy heart blood flows from the right atrium to the right ventricle where it is then pumped through the pulmonary artery to the lungs to be oxygenated. Blood then flows back to the heart via the left atrium to the left ventricle, which pumps this oxygenated blood through the aorta out to the body. This is how the body's organs and tissue receive oxygen, which is vital. When a baby has HLHS, the left side of the heart is underdeveloped so it cannot sufficiently pump the oxygenated blood out to the body.
Babies with HLHS do not have problems while in the womb - it is only after birth that the heart fails to work properly. This is because all babies receive oxygen from the placenta while in the womb, so blood does not need to go to the lungs. In addition, there is an opening between the pulmonary artery and the aorta, called the patent ductus arteriosus (PDA) that is present in all babies. It allows the blood to go from the right ventricle out to the body, bypassing the left side of the heart.
The PDA usually closes a few days after birth, separating the left and right sides of the heart. It is at this time that babies with undetected HLHS will exhibit problems as they experience a lack of blood flow to the body. They may look blue, have trouble eating, and breathe rapidly. If left untreated, this heart defect is fatal - usually within the first few days or weeks of life.
Once HLHS has been diagnosed, a drug called prostaglandin is given to keep the PDA open until surgery is performed. There are two surgical options for treating HLHS: a Heart Transplant or the 3-Stage Surgical Procedure, the first stage of which is called the Norwood procedure. (For bloodless surgical options, please see the Columbus Children's Hospital
website.)
Q. Surgical options
A.
HEART TRANSPLANT:
Babies with HLHS can be put on a list to receive a heart transplant. When the baby's name is at the top of the list, he or she will receive a healthy donor heart. To fight against rejection of the new heart, transplant patients need to take anti-rejection medications for the rest of their lives. Unfortunately, there are not enough donor hearts for all babies waiting for a transplant, and thus, some do not survive while waiting for a heart.
3-STAGE SURGICAL PROCEDURE:
An alternative to a heart transplant is the 3-Stage Surgical Procedure. The 3-Stage Procedure reconstructs the child's heart allowing it to work using only two of the heart's four chambers.
The first stage is called the Norwood procedure, or the "Modified Norwood" which was developed in 1979 by Dr. William Norwood. Because the left ventricle cannot pump blood adequately out to the body, the Norwood procedure allows the right ventricle to pump blood to both the lungs and the body. This surgery is usually performed during the baby's first week of life. A new version of this first surgery is called the "Sano Shunt." Ask the surgeon about the pros and cons of the traditional Norwood vs. the Sano Shunt, how many of each he has performed, and what the success rates are.
The second stage procedure, called the Hemi-Fontan or Bidirectional Glenn, reduces the work of the right ventricle by allowing it to pump blood only to the body, and allowing most of the blood to flow automatically from the body into the lungs. The second stage is performed when the pressure in the baby's lungs has decreased, no longer requiring the pumping action of the right ventricle to get blood into the lungs. This surgery is usually performed at about 4-6 months of age when the traditional Norwood has been performed. When the Sano Shunt is performed, the second surgery usually needs to be done earlier - at about 3-4 months of age - and the babies need constant monitoring to determine when they are ready for the second surgery.
The third and final stage, the Fontan, allows the rest of the blood coming back from the body to go to the lungs. There are two different ways to perform the Fontan: The Lateral Tunnel Fontan, the traditional approach, and the newer External Conduit Fontan. The Lateral Tunnel Fontan is usually performed at about 18 months - 3 years of age, and the External Conduit Fontan is usually performed at about 3-4 years of age.
The External Conduit Fontan uses an external conduit, or tube, that is placed just outside the heart. It is hoped that by using this conduit that the potential for arrhythmias will be greatly reduced in the future. However, this is a relatively new procedure and the outcomes will not be known for several years. It is usually done later than the Lateral Tunnel Fontan because the child has to be big enough to handle a conduit that can handle the blood flow as the child grows.
There are pros and cons of each type of Fontan procedure, so make sure you discuss with your surgeon the different types of Fontan operations and what the risks and benefits are of each.