Coarctation of the Aorta is a
congenital heart defect that happens when there is a narrowing
of the aorta as it makes the turn to supply the lower part of
the body. The coarctation (narrowing) is usually located, just
after the takeoff of the left subclavian artery (the branch to
the left arm).
The left heart pump (Left Ventricle),
then has to pump harder to force the blood to get through the
narrowed area, so that the abdomen and legs can receive enough
blood, with time the left ventricle muscle becomes thicker (hypertrophied).
The blood pressure gets higher,
so as to push the blood across the narrowed area. As the blood
squeezes through the obstructed area, it scatters under high
pressure into strong jets; most of which move the blood forward
but others hit hard against the walls of the aorta. Since so
much moving energy is wasted in trying to force the blood through,
the pressure beyond the narrowed area itself will be low.
In your child, this leads to
high pressure in the arms and low pressure in the legs. High
pressure in the arms would also be transmitted to high pressure
to the arteries going to the brain. If this pressure goes untreated
it may affect the arteries in the brain and cause stroke.