A-V Canal defect, also called Atrioventricular septal
defect (AVSD) or endocardial cushion defect, is a heart defect
involving the valves between the heart's upper and lower chambers and
the walls between the chambers. A similar defect to atrioventricular septal
defect is primum atrial septal defect. AV canal is rarely seen except in
children with Down Syndrome and its cause is not known.
In The Normal Heart:
The heart has two upper chambers called the atria, separated from
each other by a wall called the atrial septum. It also has two lower
chambers called the ventricles, separated from each other by a wall
called the ventricular septum. In the normal heart, the valve between
the right atrium and right ventricle is called the tricuspid valve and
the valve between the left atrium and the left ventricle is called the
In children with AVC, the tricuspid and mitral valves are not normally
developed but rather form one common valve which separates the heart
into two chambers, upper and lower (1) This will impair the growth of
the atrial and ventricular septum. This is also aggravated by the
presence of a hole in the atrial septum (2) and another one in the
ventricular septum (3) . First, oxygenated blood coming from the lungs
goes back to the right side through the holes. This results in a
larger amount of blood in the right side to be pumped again to the
lungs. The heart has to work harder to take out the extra blood.
Second, there is a leakage in the abnormal valve which increases the
workload of the heart.
How does it affect the Child:
Symptoms appear between 4 and 8
weeks of age, as a result of the extra workload. Children with AVC develop signs of congestive heart
failure such as rapid breathing, feeding problems, slow weight gain,
low energy, and cold, clammy sweating.
Some babies will have some blue color in the lips or under their fingernails
especially when they cry. This is called cyanosis and occurs in case
of leakage through the hole when the blood is going from the
right side to the left side of the heart.
AVC can also lead later to pulmonary hypertension due to the
extra pulmonary blood flow. The pulmonary artery taking blood from the
heartís right side to the lungs will be taking an extra blood flow.
Over time, the arteries will become thick and stiff forcing the heart
to work even harder.
After the surgery, it is not necessary for the child to restrict
exercise, competitive and athletic activities can be practiced.
Can it be fixed:
AVC is diagnosed by an echocardiogram, Chest X-ray and oxygen
saturation tests can be done. A Cardiac catheterization is done if
there are an questions not clearly answered by the echocardiogram or
if there is concern about pulmonary hypertension.
In AVC, the problem does not resolve with time and most children must
undergo heart surgery. Most children do very well after surgery.
Before undergoing surgery, some precautions must be taken. First, the
congestive heart failure must be controlled by giving medications like
Digoxin or Lasix. Medicines that lower blood pressure like captopril
are also sometimes used to decrease the work of the heart.
Second, Infant-rich formula should be given to the child to promote
weight gain. If the baby still doesnít gain weight, surgery may be
During the surgery, one or two patches will be placed to divide the
common valve into right and left sides and close the holes. This is
performed after beginning heart/lung bypass to support the circulation
during the repair itself. Stitches are also placed in the valve to
decrease valve leakage.
What should the parents do:
Follow the Doctor's advice on:
1- Giving Medicine
2- Return visits to doctor
3- Special tests
4- Extreme care with Dental procedures. Tell the dentist about the
problem BEFORE he fixes child's teeth to avoid infection in the heart.