The causes of hypoplastic left heart syndrome (HLHS) are unknown, but may include heredity, gender, other syndromes, and maternal behavior. Structural malformations and underdevelopment of the left side of the heart are thought to be the direct cause. HLHS is more common in boys and may be linked to minor left-sided heart defects and certain genetic conditions. Some drugs and lack of folic acid may increase the risk. HLHS is typically fatal without surgery, but can be managed with a series of surgeries or a heart transplant.
The causes of hypoplastic left heart syndrome (HLHS) remain elusive. There is not a single dysfunction of a gene that can indicate it or a maternal behavior that always predicts it. In general, doctors believe that HLHS is caused by a number of factors. These may include heredity, gender, the presence of other syndromes, and occasionally maternal behavior.
While the fetus is developing, the direct cause of HLHS is thought to be a structural malformation and underdevelopment of the left side of the heart, including the ventricle, atria, and aortic and mitral valves. Some doctors believe that this process can begin as early as the eighth week of fetal life. One theory is that the mitral valve and aorta develop improperly and block blood flow to the left atrium and ventricle. Without nutrient-rich blood, these structures cannot grow.
The reason for the initial abnormalities is not explained which means that the underlying cause of this condition is still mysterious. In recent years, some research has suggested a link between minor left-sided heart defects, particularly of the aorta, and an increased risk of HLHS. The condition may be more likely to occur in children whose parents, aunts or uncles, or grandparents have left-sided defects. Researchers also know that parents with a child with HLHS are more likely to have another child with the condition.
An additional factor that appears to be a partial cause of hypoplastic left heart syndrome is gender. Boys have the condition more often than girls and can account for approximately 75% of all HLHS cases. This suggests that gender alone may increase risk.
Some genetic conditions are associated with HLHS. These include Holt-Oram, Turner and Noonan syndromes. However, these conditions do not consistently present with an undersized left side of the heart and could cause other heart defects.
While no single maternal behavior is identified as a cause of hypoplastic left heart syndrome, there are a few things that can increase your risk for all heart defects. The use of some illegal or prescribed drugs has been shown to increase the chances of abnormal development of the fetal heart. Not taking folic acid before conception and in early pregnancy is now also reliably linked to an increased likelihood of heart defects.
Despite these potential known causes, it’s not that unusual for a baby to be born with HLHS without possessing any risk factors for the condition. When this occurs, the belief that the cause of hypoplastic left heart syndrome is multifactorial is emphasized. In other words, it comes from numerous causes.
Researchers have not yet discovered the exact combination of factors responsible for HLHS, and it’s possible that there isn’t one. The condition is always fatal without surgery, which is typically done in the first few days of life. HLHS is currently not curable, but a series of organized surgeries or a heart transplant can prolong life for years.
Protect your devices with Threat Protection by NordVPN
