When the left side of the heart remains under-developed, it is known as hypoplastic left heart syndrome, or HLHS. In HLHS, the mitral valve that separates the two left chambers (left atrium and left ventricle) of the heart is too small or closed off entirely. The left ventricle, which is responsible for pumping blood is also too small, as is the aortic valve, which separates the left ventricle from the aorta. It may even be closed in some cases.
A newborn with HLHS may have blue or purple skin, lips, or nails–known as cyanosis; difficulty breathing or feeding; and be lethargic. If undetected the baby will present with circulatory collapse and shock. To confirm the diagnosis of HLHS, your doctor will require echocardiogram, electrocardiogram, chest X-ray, and measurement of blood oxygen levels. HLHS can only be repaired surgically.