Heart: HLHS

Hypoplastic Left Heart Syndrome
(HLHS) is rare but serious. It is the most common
cause of death from heart disease during the first
week of life. With surgical repair or a heart transplant,
about 70% of children born with HLHS live at least 5
years.

In infants born with HLHS, the left ventricle and the
aorta are small and underdeveloped. The left ventricle
is the lower-left chamber of the heart and is
responsible for pumping oxygen-rich blood to the
body. The aorta is the artery that receives oxygen-rich
blood from the left ventricle and sends it through the
body. When the left ventricle and the aorta are too
small, they can't supply the body with enough blood.

Also in HLHS, the mitral and aortic valves are often
narrow or absent. The mitral valve acts like a door that
opens to let blood into the left ventricle. The aortic
valve lets blood out of the left ventricle. Without these
openings, the left ventricle is shut off from the rest of
the heart and the aorta. That means the left ventricle
cannot pump any oxygen-rich blood into the body.
Instead, the oxygen-rich blood returns to the right side
of the heart through an atrial septal defect (ASD), a
hole in the wall that divides the right and left sides of
the heart.

In newborns, the atrial septal defect lets oxygen-rich
blood reach the body because blood can pass from
the right side of the heart and into the aorta, without
going through the left side of the heart. The right side
of the heart pumps blood into the pulmonary artery,
and then a channel called the ductus arteriosus
connects the pulmonary artery to the aorta. The
ductus arteriosus is an important pathway in the fetal
heart, but it closes in the first few days after birth.

Until the ductus closes, oxygen-rich blood enters the
right side of the heart through the atrial septal defect.
The right side of the heart then pumps blood into the
pulmonary artery, and the ductus arteriosus lets blood
flow into the aorta. The aorta carries this oxygen-rich
blood to the body.

This means that for the first few days after birth, the
baby may seem normal because oxygen-rich blood is
reaching the rest of the body. But when that ductus
closes, oxygen-rich blood no longer has a way of
entering the aorta.

When there isn't enough oxygen-rich blood reaching
the body, the baby's skin may turn blue. This is called
cyanosis. Once this happens, the baby needs surgery
or a heart transplant right away.

Taken from Hope for HLHS