Hypoplastic Left Heart Syndrome
The Normal Heart
The normal heart has four chambers, two upper chambers called atria, and two lower chambers called ventricles. The job of each chamber is different, but, in general, the atria (top) receive blood into the heart, and the ventricles (bottom) pump blood out of the heart. Instead of thinking about the heart as having four chambers, it is often easier to think of the heart as having two sides. The right side of the heart pumps blood to the lungs, and the left side of the heart pumps blood to the body.
The cycle of blood through the heart and body begins when blood from the body is returned to the right side of the heart, and is pumped by the right ventricle through a large blood vessel called the pulmonary artery to the lungs. From the lungs, blood is returned to the left side of the heart, where it is pumped by the left ventricle out through another large vessel called the aorta to the body.
What is hypoplastic left heart syndrome?
Hypoplastic left heart syndrome is among the most serious of all childhood heart defects, representing 0.02% of all live births. Hypoplastic left heart syndrome means that the entire left side of the heart (the left ventricle and the aorta) is underdeveloped.
In children with hypoplastic left heart syndrome, the left ventricle is so underdeveloped that it cannot effectively pump blood, and the aorta is too narrow to take blood to the body. To keep the body supplied with blood, the right side of the heart must do double duty and pump blood to both the lungs and the body, making it the only pumping chamber in the heart. This is called "single ventricle" physiology.
What will happen during pregnancy?
Hypoplastic left heart syndrome is a rare birth defect. Prenatal diagnosis is usually based on a fetal ultrasound that examines the heart and fetal anatomy. Once the condition is suspected, a targeted ultrasound is performed to rule out the presence of associated anomalies. A specialized ultrasound of the fetal heart, called an echocardiogram, will be performed, and an amniocentesis to look for chromosomal anomalies may be recommended. Although the ultrasound may be suggestive that there is an abnormality, the diagnosis will be confirmed after birth.
Your pregnancy will be closely monitored. The Center coordinator will keep you in contact with all of the appropriate physicians and specialists as well as coordinating the care for you and your baby after delivery.
Will a fetal treatment be required?
Currently, there are only experimental procedures for the fetal treatment of hypoplastic left heart syndrome with unknown long term results. These are not offered at the Center. If you and your fetus qualify for experimental interventions, the Center can help coordinate a referral to the appropriate facilities, if you desire.
What special considerations should be made for delivery?
Type of delivery - Typically, a cesarean delivery is not necessary unless there are other factors determined by your obstetrician. A delivery plan will be carefully developed by your team of physicians at the Center and will be discussed with you and your obstetrician.
Place of delivery - The baby should be delivered at a hospital that is well prepared to handle babies with congenital heart defects. There should be a neonatal intensive care unit with the capability to provide specialized care and pediatric cardiology and pediatric cardiovascular surgery services.
Time of delivery - There is usually no reason to intentionally induce early delivery.
What will happen at birth?
IImmediately following delivery, doctors will carefully evaluate your baby. In most cases, there is no immediate danger to the infant. Your newborn will be transferred to the neonatal intensive care unit and stabilized. Your pediatric cardiologist will evaluate the baby. The newborn may need help with breathing and blood pressure.
Surgical Treatment
Children with hypoplastic left heart syndrome typically require three operations to fix their hearts, which take three to four years to complete. The first procedure, the Norwood procedure, is done within the first two weeks of life and is a serious, complicated operation. In the United States, approximately 15 percent of the babies who undergo the Norwood procedure will die before the second operation, which usually occurs between 4-6 months of age.
There is good reason to have hope for babies born with hypoplastic left heart syndrome. Many babies do live, have normal development and enjoy a good quality of life. The chances of dying from the second and third operation are much less than the first, so those babies that make it through a Norwood procedure have a very good chance of doing well.
The Center team will help care for you and your infant with hypoplastic left heart syndrome. The Center will develop a comprehensive plan with all of the physicians and specialists involved in the care of you and your newborn before, during, and after delivery.
To learn more about hypoplastic left heart syndrome, please visit the Children's Heart Institute at Children's Memorial Hermann Hospital.
Note: This information regarding your condition is meant to be a helpful, informative introduction. Because every newborn is different, this may not be applicable to all cases, especially if there are additional defects. Your team of experts at the Center will provide you with information specific to your pregnancy.