Birth Defects: Hypoplastic Left Heart Syndrome
What is Hypoplastic Left Heart Syndrome?
Hypoplastic left heart syndrome (HLHS) is a congenital birth defect – that is present at birth. Approximately 35,000 infants, or 1 in every 125, are born with a heart defect, and 1 to 3.8 percent of all congenital cardiac birth defects present as hypoplastic left heart syndrome (Connor and Thiagarajan). “Heart defects are among the most common birth defects and are the leading cause of birth defect-related deaths … In the United States, about 1.4 million children and adults live with congenital heart defects.” (March of Dimes)
Basically, a baby with HLHS has a heart that is underdeveloped (hypoplastic) on the left side. In a normal heart, oxygen-poor blood (as indicated by the blue arrows in the diagram below) travels to the right half of the heart from the body and is pumped to the lungs through the pulmonary artery. The oxygen-rich blood (as indicated by the red arrows in the diagram below) is then pumped back to the left side of the heart, and is pumped out to the body through the aorta (CHB).
Normal Heart Versus HLHS Heart (Courtesy of Children's Hospital Boston)
In the case of HLHS, the small or underdeveloped structures on the left side prevent oxygen-rich blood from reaching the other areas of the body where oxygen is needed. The mitral valve, aortic valve and aorta can also be affected.
Symptoms and Causes of Hypoplastic Left Heart Syndrome
A baby born with HLHS is usually full-term and initially appears healthy. There is no heart murmur or sound that would normally tip off doctors of a problem, which is usually the case in adult-related heart diagnoses.
Within a few hours, however, the baby starts exhibiting symptoms that alert doctors and nurses that something is not quite right. A baby with HLHS may have symptoms such as:
- Grayish-blue skin tone (cyanosis)
- Rapid, difficult/labored breathing
- Cold hands and feet
- Poor pulse
- Poor suckling and feeding
- Pounding heart
- Drowsiness or inactivity
There is no known cause for congenital heart defects as genetic and environmental factors may each play a role. It is known, though, that women who contract German measles (Rubella) in the first three months of pregnancy are at higher risk for having a baby with a heart defect, as do mothers who take isotretinoin (acne medication – Accutane), thalidomide, certain anti-seizure medications, and trimethoprim-sulfonamide (antibiotics sometimes used to treat urinary-tract infections). (March of Dimes)
“At least 30 percent of children with chromosomal abnormalities, such as Down syndrome … and Turner syndrome, have heart defects. Heart defects are also common in children with a variety of inherited disorders …” (March of Dimes)
Obviously, parents with a history of congenital heart disease also are at increased risk of having a baby with this birth defect as well.
Treatment and Prevention of Hypoplastic Left Heart Syndrome
Hypoplastic left heart syndrome “can be diagnosed by fetal echocardiography between 18 and 22 weeks of gestation.” (Connor and Thiagarajan)
Treatment initially involves medication to keep the arteries open and blood circulating while planning for surgery is done. Medication cannot correct or fix the problem. Surgery is always required. There are actually a series of heart surgeries performed to, essentially, rebuild the heart in such a way that it can do what it needs to to supply the body with oxygen.
The first surgery (within days of birth) is called the Norwood, which aims at building a new aorta. The second surgery, usually performed at 4 to 6 months) is called the Glenn shunt or hemi-Fontan procedure which connects the superior vena cava carrying oxygen-poor blood from the upper part of the body directly to the pulmonary arteries to be oxygenated by the lungs. The final step is a Fontan procedure, usually performed between 18 and 36 months, and connects the inferior vena cava, which carries oxygen-poor blood from the lower body, directly to the pulmonary artery. This leaves the right ventricle to pump oxygenated blood out to the rest of the body. (PubMed)
This three-step treatment plan is an alternative to a heart transplant, which is particularly difficult given the unavailability of baby-sized hearts to transplant. “If left untreated, hypoplastic left heart syndrome is fatal … Survival after the first stage is more than 75%. The child’s outcome after surgery depends on the size and function of the right ventricle.” (PubMed)
The fetal heart is completely developed by week eight of gestation, often before a mom is even aware she’s pregnant. Similar to the recommendation for women of childbearing years to take pre-emptive amounts of folic acid to prevent neural tube defects (eg. spina bifida and anencephaly), doctors are also suggesting that omega-3 fatty acids also be added. New research is emerging to show that omega-3 fatty acids (ALA, EPA and DHA) not only help the fetal development of the brain and eyes, but also promote the development of fetal cardiac and respiratory systems and possibly reduce chances of pre-eclampsia since omega-3s lower blood pressure.
A recent study also suggests that adding Vitamins A, C and E even late in pregnancy can “alleviate heart hypoplasia” (Journal of Pediatric Surgery) in rats.
It is to be noted, though, that these methods do not eliminate the possibility of having a baby with a congenital heart defect, and obviously more research needs to be done to see precisely the effect these vitamins have on actual birth rates involving HLHS.
Sources:
Congenital heart defects. March of Dimes. Web. Mar 26, 2012.
http://www.marchofdimes.com/baby/birthdefects_congenitalheart.html
Hypoplastic left heart syndrome (HLHS). Children’s Hospital Boston. Web. Mar 26, 2012.
http://www.childrenshospital.org/az/Site502/mainpageS502P0.html
“Hypoplastic left heart syndrome” Connor, Jean A and Thiagarajan, Ravi. Orphanet Journal of Rare Disease. Web. Mar 26, 2012. Orphanet Journal of Rare Diseases 2007, 2:23
http://www.ojrd.com/content/2/1/23
Hypoplastic left heart syndrome. Mayo Clinic. Web. Mar 26, 2012.
http://www.mayoclinic.com/health/hypoplastic-left-heart-syndrome/DS00744/DSECTION=symptoms
Hypoplastic left heart syndrome. PubMed Health U.S. National Library of Medicine. Web. Mar 26, 2012.
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002096
Omega-3 Fatty Acids & Fetal-Pregnancy Health. Early-Pregnancy-Tests.com. Web. Mar 26, 2012.
http://www.early-pregnancy-tests.com/omega-3.html
Omega-3 fatty acids. March of Dimes. Web. Mar 26, 2012.
http://www.marchofdimes.com/pregnancy/nutrition_omega3.html
“Effects of prenatal vitamins A, E, and C on the hypoplastic hearts of fetal rats with diaphragmatic hernia” González-Reyes , Salomé, Martínez, Leopoldo, and Tovar, Juan. Journal of Pediatric Surgery, Vol. 40. Iss. 8, Aug 2005, Pg. 1269-1274.
http://www.sciencedirect.com/science/article/pii/S0022346805003696
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