Hypoplastic left heart syndrome (HLHS)
is a problem with the heartÕs structure that is present at birth (congenital). It occurs when parts of the left side of the heart (mitral valve, left ventricle, aortic valve, and aorta) do not develop completely. The underdeveloped left side of the heart is unable to provide enough blood flow to the body, which decreases the oxygen-rich blood supply. Babies with HLHS might look normal at birth, but will develop symptoms of HLHS within a few days. These symptoms might include: poor feeding, problems breathing, pounding heart, weak pulse, and ashen or bluish skin color. The cause of HLHs is presently unknown. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.