What is an AVSD (atrioventricular septal defect)?
The normal heart has 2 valves in the middle separating the upper chambers (the atria) from the lower chambers (the ventricles).These valves are called the tricuspid and the mitral valve. Some people are born with a single common AV valve in the middle of the heart instead of 2 normal valves. This condition is associated with holes in the heart. The common AV valve may also be leaky. There are 3 types of AVSD. All types of AVSDs are more common in children with Downs syndrome but can occur in anyone.
A PRIMUM ASD – there is a common AV valve and a hole just above it,(shown by the yellow star). The hole is between the 2 upper pumping chambers (atria).
A COMPLETE AVSD – there is a common AV valve and holes above and below it between the 2 upper (atria) and 2 lower pumping chambers (ventricles).The holes are shown by the yellow stars.
An Intermediate AVSD – there is a common AV valve and a hole between the 2 upper pumping chambers (atria) and a very small hole between the 2 lower pumping chambers (ventricles).
At birth, most affected babieswith either type of defect will have no symptoms.
Most babies and children with a primum ASD remain symptom free.
After the first few weeks of life those with larger holes or with major leaking of the common valve, usually those with a complete AVSD may become breathless, tire more easily, have slower weight gain with feeding difficulties, become sweaty and can be more prone to respiratory infections (such as bad colds and bronchiolitis).
Timing of treatment depends on the specifics of each individual child’s heart. Some babies are breathless with feeding difficulties from early on. Treatments include the following (not required for all children):
- Diuretic liquid medicine treatment to help treat heart failure,which causes increased fluid in the lungs, resulting in breathlessness eg.frusemide and spironolactone medicines.
- Calorie supplements added to milk eg. Powder added to breast milk or high calorie formula milk.
- Feeding through a special tube passed from the nose to the stomach. This is not always needed, but is helpful for babies who are too breathless to feed consistently.
- Medicines for gastroesophageal reflux if required.
Most children with a primum ASD are symptom free. Surgery can be delayed until the child is bigger, often until they are 2-4 years old, when surgical risks are lower. Repair of the defect involves pacing a patch on the hole via open heart surgery using a cardiac bypass machine. There will be a midline sternotomy scar in the middle of the chest and hospital stay is usually 5-10 days.
Babies with a complete AVSD are likely to require surgery early in life. This may be possible with a single stage complete repair, where the surgeon repairs the defect in the abnormal heart valve causing a leak (the ‘cleft’) and also closes the holes with patches. This is open heart surgery, using a cardiac bypass machine. There will be a midline sternotomy scar and hospital stay is usually 1-2 weeks. Longer stays may be needed especially for smaller sicker babies.
Some babies are too sick and small to tolerate a complete repair and require a 2 stage operation with an initial palliative operation where the surgeon places a band around the pulmonary artery. This band reduces the amount of blood which passes from the holes to the lungs. Later when the baby is bigger a second bigger open-heart operation is performed to repair the AVSD.
Dr Naqvi works with an excellent team of NICOR audited congenital cardiac surgeons and if necessary will refer your child to the one who is best for your child’s heart.
Dr Naqvi has cared for many babies and children with primum ASDs and complete atrioventricular septal defects (AVSDs) and has followed them up until adulthood. She says “The future for children with these types of heart defects is usually very good. A small number may need further lower risk surgery later in life. Even babies who are very sick and struggling to gain weight turn the corner after surgery.
It is so wonderful to see them when they are older happily running around in the clinic, with no memories whatsoever of the difficult times they had when they were little.”