Atrio-Ventricular Septal Defect (AVSD/AVCD)

This is an acyanotic congenital heart disease (CHD). Congenital defects are the defects that are present at birth.

It is characterised by a presence of atrial and ventricular septal defect      (ASD and VSD) with a common atrio-ventricular valve (common atrio-ventricular valve instead of 2 separate atrio-ventricular valves). This is also known as atrio-ventricular canal defect (Endocardial cushion defect / AVCD / AVSD).

Atrio-ventricular canal defect leads to overflow of blood to both lungs that leads to difficulty in breathing, poor feeding tolerance etc.

If untreated, then AV canal defect can leads to heart failure and increase in lung pressures (pulmonary arterial hypertension, PAH).

Cause of Atrioventricular septal defect in children

Although cause is unknown but AV septal defect is commonly associated with a syndrome known as Downs Syndrome, or also can be associated with very complex congenital cardiac defects.

Types of AV septal defect

AV septal defect can be associated with

• Large VSD with large primum ASD (complete AV canal defect): Most common type of AV canal defect
• Small VSD with large ASD (Transitional AV septal defect)
• Only primum ASD (Primum AV canal defect)

Lower chambers of the heart may be equal in size (balanced AV septal defect) or one of the lower chamber may be small in size (unbalanced AV septal defect).

Sometimes, AV canal defect can be associated with narrowing of the right sided big vessel of the heart (known as pulmonary artery stenosis, PS).

Occasionally, pulmonary artery is not patent (pulmonary atresia), meaning by that there is no flow to the lungs from the heart, instead blood supply to the lungs are from additional abnormal channels like Patent ductus arteriosus (PDA).

Symptoms of complete AV septal defect in children

Symptoms due to AV canal defect depends on how big is the size of VSD and whether PS is there or not.

• Difficulty in breathing
• Poor weight gain/rapid weight loss
• Heart failure signs
• Excessive sweating
• Heart valve leakage
• Bluish discoloration of the lips and skin (cyanosis, if severe pulmonary artery stenosis or pulmonary atresia are present).
• Cyanosis can also occur when AV septal defect was not repaired in early part of life preferably before one year of age (Eisenmenger AV septal defect)

Symptoms of partial AV septal defect in children

Child may have following issues:

• Asymptomatic
• Heart beat disorders (arrhythmia)
• Difficulty in breathing
• Pulmonary hypertension
• Heart valve leakage
• cardiac failure

Diagnosis of Atrioventricular septal defect in children

AVSD can be diagnosed antenatally by doing “Fetal Echocardiogram Test”.

After birth of the baby, it can be suspected by symptoms as mentioned above and also by hearing murmur (Murmur of AV canal defect).

It can be easily diagnosed and confirmed by doing “Pediatric Echocardiogram Test’.

Chest X ray and ECG may help in suspicion of AVSD heart disease.

Sometimes, we need to do cardiac catheterization for assessing operability if patient presents in later infancy.

Treatment of AV septal defect in children

Surgery is the only treatment option for repairing the defect (AV septal defect surgical repair).

If both lower chambers of the heart are adequate in size (balanced ventricles) then two ventricle repair is possible and type of surgery depends on the variety of AV septal defect.

If ventricles are unbalanced then we need to follow the single ventricle pathway of treatment (meaning that we can not make normal lower chamber of the heart that is small in size).

In this, we need to do three surgeries for palliating the heart defect. These are named as PA banding (at the age of 2 months approx), followed by Glenn shunt (6 months to one year of age), and then Fontan operation (2-4 years of age).

When there is narrowing of the pulmonary artery (PS) is present then instead of PA banding, we need to do BT shunt at 1-2 months of age or can be done early if there is very tight narrowing or there is no blood flow to the lungs from the heart (pulmonary atresia).

We close the holes and if there is narrowing of the valve ten simultaneously we remove the narrowing as well.

We need to repair the mitral valve as this is associated with a gap in AV canal defect (cleft mitral valve). Sometimes, in later part of the life, when there is huge leakage of the valves then we need to replace the valve (Mitral valve replacement, MVR).

In case of complete variety of AV canal defect, we need to make two separate valves in addition to closure of ASD and VSD.

Follow-up after surgery of AV septal defect

If there is good surgical outcome, then there is no need for any activity restrictions.

But, child need to be on regular and life long follow-up with a paediatric cardiologist form leakage of heart valves, narrowing in any valve, heart beat disorders, artificial heart valve assessment if replaced etc if any.

Atrio ventricular canal defect with Pregnancy

Females who underwent properly repaired AVSD in early infancy can have plan pregnancy.

However, if there is any serious heart or lung issues are there, then it is contraindicated especially when lung pressures are very high (Eisenmenger AV canal defect).

Patients need proper pre-pregnancy counselling by a paediatric cardiologist.

Risk associated with AV septal defect

Complications or risks associated with complete AV septal defect may include:

• Cardiac enlargement
• Pulmonary arterial hypertension
• Infections of the lungs

Risk associated with AV canal defect in later part of the life

Sometimes, even when with good surgical outcome, patient is being at risk of the following risks:

• Heart valve leakage
• Narrowing of the outflow tracts or cardiac valves
• Arrhythmia
• Breathing difficulties if associated with residual pulmonary hypertension

Symptoms associated with above mentioned risks can be:

• Difficulty in breathing
• Early fatigue or tiredness
• Irregular heart beat

Sometimes, when indicated, we need to repeat the surgery for correcting the risks associated (Re surgery of AV septal defect).