Atrioventricular Septal Defect
Down's Heart Group
P.O. Box 4260
Dunstable, Beds, LU6 2ZT, United Kingdom
Tel. & Fax: 0845 166 8061
On-line community:
Reprinted with the permission of Penny Green, Director
© 1998 Down's Heart Group
UK Charity Nº 1011413

The AVSD defect is the most common congenital heart defect found in children with Down's Syndrome, accounting for something in the region of 50% of the total.

AVSD heart

Diagram shows the heart looking from the front of the patient

In its complete form there is a hole in the wall between the top chambers (atria) and a hole in the wall between the bottom chambers (ventricles), and one common valve between the two atria and the two ventricles. In the partial forms there may not be a hole between the bottom chambers (ventricles) or the Mitral and Tricuspid valves may not be joined together, but either or both may leak, known as valve incompetence.

Because of the high pressure in the left ventricle (needed to pump the blood around the body), blood is forced through the holes in the septum when the ventricle contracts, thus increasing the pressure in the right ventricle. This increased pressure results in excess blood flow to the lungs which may result in Pulmonary Hypertension.

Some of the early symptoms which may be exhibited are difficulty in feeding, poor weight gain, fast irregular breathing and a degree of cyanosis (blueness) particularly noticeable around the mouth, fingers and toes. Clinical examination may show an enlarged heart and liver, and a diagnosis of 'heart failure' may be given. This is not as frightening as it sounds, it is in fact the medical term used to indicate that the heart is working inefficiently due to the demands the body is placing on it. Because of the flow of blood from one side to the other, the heart has to work harder than normal.

Not all children will exhibit symptoms early in life, and those that do will not necessarily show all of these.

Early treatment may involve the use of diuretics such as Frusemide and Spironolactone to control the fluid retention around the body and to reduce the volume of blood in the circulation, thus making the heart's workload easier. These may be used in conjunction with other drugs such as Digoxin, to increase the contraction of the heart muscle.

Slow weight gain may lead to the addition of additives such as Calogen or Duocal to a baby's milk to increase calorie intake. Severe feeding problems may necessitate feeding by way of a naso-gastric tube (through the nose and directly into the stomach), so that energy is not used up in obtaining nourishment.

Most cases of AV Canal are suitable for surgical intervention, this generally takes place within the first six months of life. In a few cases with particularly increased pulmonary hypertension, it may be recommended that a banding of the Pulmonary Artery is carried out first to reduce the blood flow to the lungs in order that corrective surgery can be considered later.

If the condition is left unoperated, the increased blood pressure in the lungs causes damage which eventually makes surgery impossible, as the body adjusts to these pressures and could not cope with the alteration surgery would cause.

Follow up Advice
Often following surgery there remains a leaky valve which requires regular monitoring in case more surgery is needed, although in many cases the heart copes very well with the leakage and no further treatment is required. Sometimes bouts of illness may place an additional strain on the leaky valve, but this may be alleviated by treatment with diuretics for a short period. There may be times when all chest infections require quite energetic treatment. The repeated use of antibiotics, if used properly, is very helpful and does not reduce the child's resistance to infections.

All patients with a cardiac defect, whether repaired or not, will require antibiotic cover during any dental treatment to prevent any bacteria entering the blood stream from where they can reach the heart causing bacterial endocarditis (infection of the heart lining), which can be very serious. For similar reasons, any illness with a fever as measured under the arm or under the tongue for two minutes, of 104°F or 40°C or higher should generally lead to blood tests and the urgent use of antibiotics. <BGSOUND SRC="vsd.wav" LOOP="INFINITE">

  Revised: December 19, 2005.