Atrioventricular Septal Defect (AVSD)
Information for teenagers and adults with an atrioventricular septal defect
An atrioventricular septal defect (AVSD) is a congenital heart condition involving the central part of the heart, where the walls between the heart chambers and the atrioventricular (AV) valves develop.
AVSD is sometimes also called an atrioventricular canal defect or endocardial cushion defect.
There are several forms of AVSD, ranging from a partial defect involving mainly the atrial septum and left AV valve to a complete defect involving both the upper and lower chambers of the heart and a common AV valve.
Most people with a complete AVSD have surgery during infancy or childhood. Some people with a partial AVSD may not be diagnosed until later in childhood or even adulthood.
After successful repair, most people can lead active and fulfilling lives. However, AVSD is a lifelong congenital heart condition, and ongoing follow-up with a cardiologist experienced in adult congenital heart disease is important.
How does AVSD affect the heart?
Normally, the heart has four chambers separated by walls called septa.
The mitral valve controls blood flow between the left atrium and left ventricle, while the tricuspid valve performs the same role on the right side.
In AVSD, the central structures of the heart have developed differently. This can result in openings between the chambers and abnormalities of the AV valves.
The exact effect on the circulation depends on the type of AVSD.
Are there different types of AVSD?
Yes. The main forms are partial AVSD and complete AVSD, although there are also intermediate or transitional forms.
Partial AVSD
A partial AVSD usually includes a hole between the two atria known as a primum atrial septal defect.
There are two separate AV valves, but the left AV valve has an abnormal structure and may leak.
The left AV valve in an AVSD is sometimes referred to as the mitral valve, although its anatomy is different from a normal mitral valve.
Some people with partial AVSD remain well during childhood and are diagnosed only later in life because of a heart murmur, an enlarged heart or symptoms.
Complete AVSD
In a complete AVSD, there are defects involving both the atrial and ventricular septum and a single common AV valve rather than separate mitral and tricuspid valves.
This allows substantial additional blood flow through the lungs and usually causes symptoms during infancy.
Complete AVSD is therefore generally repaired surgically early in life.
Transitional or intermediate AVSD
Some people have anatomy between the partial and complete forms, with features of both.
Your congenital cardiologist can explain your individual anatomy and the type of repair you have had.
What surgery is performed?
Surgery aims to close the openings between the heart chambers and create or reconstruct functioning right and left AV valves.
In complete AVSD, surgery usually involves closing the atrial and ventricular components of the defect and dividing the common AV valve into separate right and left valves.
In partial AVSD, surgery usually involves closing the primum ASD and repairing the left AV valve.
The precise operation varies depending on the anatomy.
Although surgery repairs the major abnormalities, it does not make the heart completely anatomically normal. The reconstructed AV valves and other areas of the heart can change over time, which is why follow-up remains important in adulthood.
What problems can occur after AVSD repair?
Many people remain well following repair, but several issues can develop later in life.
Left AV valve regurgitation
The most common long-term issue is leakage of the left AV valve.
This is called left AV valve regurgitation.
A small amount of leakage is common and may remain stable for many years.
If regurgitation becomes more severe, it can cause enlargement of the left side of the heart and eventually lead to symptoms such as breathlessness or reduced exercise capacity.
Some people require further surgery to repair or replace the left AV valve.
Left ventricular outflow tract obstruction
Some people with AVSD can develop narrowing in the pathway through which blood leaves the left ventricle and enters the aorta.
This is called left ventricular outflow tract obstruction.
It can develop or progress even after the original AVSD has been repaired and occasionally requires further surgery.
Residual holes
Occasionally a small residual ASD or VSD remains after surgery.
Small residual defects may cause no significant problems and simply require monitoring.
Heart rhythm problems
The electrical system of the heart is located close to the area affected by an AVSD and can also be influenced by previous surgery.
Some people develop:
A slower than normal heart rhythm
Heart block
Atrial flutter or atrial fibrillation
Other abnormal heart rhythms
Occasionally a pacemaker is required.
AVSD and Down syndrome
AVSD has a strong association with Down syndrome (trisomy 21), particularly complete AVSD.
However, many people with AVSD do not have Down syndrome, and partial AVSD is commonly seen in people without any chromosomal condition.
People with Down syndrome may have additional health considerations that influence their congenital heart disease care, including an increased tendency to develop pulmonary hypertension.
Pulmonary hypertension
Before repair, a large AVSD can cause excessive blood flow through the lungs.
If a significant defect remains untreated for a long period, this can damage the blood vessels within the lungs and cause pulmonary hypertension.
Early childhood repair has made severe pulmonary vascular disease much less common in adults with repaired AVSD.
People who have pulmonary hypertension require specialist assessment and follow-up.
How to stay well
Keep up with your congenital heart checks
Adults with repaired AVSD should generally have lifelong follow-up with an adult congenital heart disease specialist.
Even if you feel completely well, follow-up allows your cardiologist to monitor:
Left and right AV valve function
Heart chamber size and function
Left ventricular outflow tract obstruction
Residual ASD or VSD
Pulmonary pressures
Heart rhythm
How often you need review depends on your individual anatomy and previous operations.
Stay active
Regular exercise is encouraged for most people with repaired AVSD.
People with a good repair, normal heart function and no significant valve disease or pulmonary hypertension can often undertake normal recreational exercise.
Exercise recommendations may be different if you have:
Significant AV valve regurgitation
Left ventricular outflow tract obstruction
Pulmonary hypertension
Reduced heart function
Important abnormal heart rhythms
If you are considering competitive sport or particularly high-intensity exercise, discuss this with your congenital cardiologist.
Look after your teeth
Good dental hygiene and regular dental care are important for people with congenital heart disease.
Most people with a successfully repaired AVSD do not routinely require antibiotics before dental procedures.
Antibiotic prophylaxis is recommended for certain higher-risk people, including some people with prosthetic heart valves or material, previous infective endocarditis, or residual defects associated with prosthetic material.
Your cardiologist or dentist can tell you whether this applies to you.
Don’t smoke or vape
Avoid smoking and vaping. Maintaining a healthy weight, blood pressure and cholesterol also helps reduce additional stress on the heart.
Pregnancy
Many women with a well-repaired AVSD, good heart function and no significant valve disease or pulmonary hypertension can have a successful pregnancy.
However, pregnancy places additional workload on the heart and can sometimes worsen AV valve regurgitation or trigger abnormal heart rhythms.
Risk is higher when there is:
Significant left AV valve regurgitation or stenosis
Reduced heart function
Pulmonary hypertension
Significant left ventricular outflow tract obstruction
A history of important abnormal heart rhythms
Women with AVSD should ideally have pre-pregnancy assessment with a cardiologist experienced in congenital heart disease and pregnancy.
This allows heart and valve function, pulmonary pressures and medications to be reviewed before pregnancy.
Does AVSD run in families?
Most congenital heart disease does not follow a simple pattern of inheritance, but people born with congenital heart disease have a higher chance of having a child with congenital heart disease than the general population.
The exact risk varies according to the underlying condition and whether there is an associated genetic diagnosis.
If you are planning a pregnancy, your congenital heart team may recommend genetic counselling and a specialised ultrasound of the baby’s heart (fetal echocardiogram) during pregnancy.
Symptoms to tell your doctor about
Contact your doctor or congenital cardiology team if you develop:
New or increasing shortness of breath
A noticeable reduction in exercise capacity
Frequent or prolonged palpitations
Dizziness or near-fainting
New swelling of your ankles or abdomen
Increasing fatigue
Unexplained fainting
A significant change in your usual symptoms
A gradual reduction in exercise capacity can sometimes be an early sign of worsening AV valve regurgitation or another change in heart function.
Emergency — get help immediately if
Seek urgent medical attention or call 000 if you develop:
Severe or rapidly worsening shortness of breath
Fainting associated with exercise or palpitations
A sustained rapid or very slow heartbeat associated with dizziness or feeling very unwell
Severe chest pain
Sudden significant deterioration in your condition
Your regular check-ups
Follow-up for AVSD may include:
Clinical review
Your cardiologist will ask about exercise capacity, breathlessness, palpitations and other symptoms and examine your heart and circulation.
ECG
An electrocardiogram records the electrical activity and rhythm of your heart and can identify conduction abnormalities that are more common in AVSD.
Echocardiogram
An ultrasound of the heart is particularly important for assessing left and right AV valve function, heart chamber size and function, residual defects, left ventricular outflow obstruction and pulmonary pressures.
Cardiac MRI
MRI is not required at every visit but can provide more detailed information about heart size, function, blood flow and anatomy when needed.
Heart rhythm monitoring
A Holter monitor or longer-term rhythm monitor may be recommended if you experience palpitations, dizziness or fainting.
Exercise testing
Exercise testing can objectively assess your exercise capacity and may help identify changes that are not obvious during everyday activities.
Questions for your doctor
What type of AVSD do I have, and what surgery have I had?
Do I have any residual holes between the heart chambers?
Is my left AV valve leaking, and how severe is it?
Is there any narrowing of the pathway from my left ventricle to the aorta?
Is my heart function normal?
Am I at increased risk of abnormal heart rhythms or needing a pacemaker?
Do I have any restrictions on exercise, work, travel or pregnancy?
Should I have genetic counselling before having children?
How often should I have a congenital heart check-up?
This information is intended as a general guide for teenagers and adults with an atrioventricular septal defect. AVSD varies considerably between individuals, and your congenital cardiologist can provide advice specific to your anatomy, previous surgery, valve function and current health.
