What are the other Names for this Condition? (Also known as/Synonyms)

• Atrioventricular Canal Defect
• AVSD (Atrioventricular Septal Defect)
• Endocardial Cushion Defect (ECD)

What is Atrioventricular Septal Defect? (Definition/Background Information)

• Congenital heart defects are relatively common birth defects involving the heart, and these may be of several types. Atrioventricular Septal Defect (AVSD) is a common complex congenital heart abnormality characterized by the presence of “holes” in the walls between the left and right chambers that may be accompanied by valve defects too
• Based on the heart structure affected (or malformed), Atrioventricular Septal Defect may be grouped into the following two types:
  • Complete Atrioventricular Septal Defect
  • Partial or Incomplete Atrioventricular Septal Defect
• In individuals with Atrioventricular Septal Defect, the blood flow circulation is abnormal; extra blood may flow to the lungs causing the heart and lungs to pump harder. Also, the blood may be deficient in oxygen levels. All these may result in congestive heart failure and other complications
• The signs and symptoms noted, the complications that may develop, and the treatment (surgical) approach that is considered/planned, are all chiefly related to the specific type of Atrioventricular Septal Defect noted in the affected individual. Nevertheless, surgery is mandated for both types of AVSD; the prognosis is normally good with adequate treatment

Who gets Atrioventricular Septal Defect? (Age and Sex Distribution)

• Atrioventricular Septal Defect affects the newborn child. It may be present at birth, but is sometimes not recognized until the child gets older (since some are mild and typically asymptomatic)
• The incidence of the condition is estimated to be around 1 in 1,900 babies
• Both male and female genders are affected
• No racial or ethnic predilection is generally observed

What are the Risk Factors for Atrioventricular Septal Defect? (Predisposing Factors)

Currently, no risk factors for Atrioventricular Septal Defect (AVSD) are definitively known. The following may increase one’s risk for the same:

• It is commonly associated with Down syndrome; between 15-20% of the individuals with the syndrome present AVSD
• A family history of heart structural abnormalities may be a risk factor
• Exposure of the pregnant woman to environmental toxins and certain medications

Congenital heart defects have been associated with AVSD that include:

• Double outlet right ventricle
• Single ventricle
• Transposition of the great vessels
• Tetralogy of Fallot

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Atrioventricular Septal Defect? (Etiology)

The exact cause of development of Atrioventricular Septal Defect (AVSD) is not well-understood. It may develop from a combination of factors that may be genetic and environmental. It is also believed that what the expectant mother consumes, such as food, drink, or even some medications, may be contributive.

• In AVSD, there are formation defects arising from the endocardial cushions, which are embryonic cardiac tissues that later develop into the septal walls, which divide the four heart chambers, and the heart valves (mitral and tricuspid valves)
• Due to abnormalities (failure of formation of the endocardial cushions) in the separation of the heart chamber walls and valves, it results in the complex heart defect AVSD. Thus, this condition is also termed as Endocardial Cushion Defect (ECD)
• The associated signs and symptoms are based on the magnitude of the defect and the presence of other underlying heart anomalies (if any). Thus, based on the severity of the condition, AVSD is classified as:
  • Complete AVSD: In this form, both atrial septal defect (ASD) and ventricular septal defect (VSD) is present. Also, instead of two distinct valves (mitral and tricuspid), there is one large common valve
  • Partial or Incomplete AVSD: In this form, only ASD, or ASD and VSD are present; and there are two distinct valves. However, the mitral valve often has a cleft (opening) that allows blood to flow back into the valve. Individuals with the partial type, sometimes do not show signs and symptoms during childhood

What are the Signs and Symptoms of Atrioventricular Septal Defect?

Mild cases of Atrioventricular Septal Defect may be present without any signs and symptoms for a long period, sometimes even into adulthood. The signs and symptoms observed in other cases may include:

• Heart murmur (a whooshing sound may be heard via a stethoscope)
• Abnormal heartbeat and weak pulse
• Shortness of breath, usually after exercise or physical activity (this may be even observed in infants who are generally active)
• Swelling in the legs (feet) or abdomen
• Infants feel tired upon feeding
• Cyanosis - bluish discoloration of the lips and skin
• Rapid breathing or heart rate
• Increased sweating
• Appetite loss
• Poor feeding in children; slow gain in weight
• Elevated blood pressure due to increased blood flow from the heart to the lungs

How is Atrioventricular Septal Defect Diagnosed?

The diagnostic tests and exams for Atrioventricular Septal Defect may include:

• Physical exam with evaluation of medical history. This includes listening to the heart using a stethoscope, to detect any unusual ‘whooshing’ sound
• Assessment of the presenting signs and symptoms, particularly pale skin, breathing difficulties, tiredness, and swollen lower limbs
• Newborn pulse oximetry screening may help the healthcare suspect the condition prior to symptom presentation
• Electrocardiogram (EKG), to measure electrical activity of the heart
• Fetal echocardiogram may be commonly used to confirm the diagnosis
• Chest X-ray, CT and MRI scan studies of the chest and abdomen, as needed
• Cardiac catheterization

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Atrioventricular Septal Defect?

Complications due to Atrioventricular Septal Defect are mostly due to a delay in detection and treatment of the condition and/or due to the presence of other accompanying heart defects. These include:

• Frequent lung infections; the individual is at risk for pneumonia
• Irreversible damage to the lungs
• High blood pressure in the lungs (pulmonary hypertension)
• Arrhythmia or abnormal heart rhythms
• Congestive heart failure
• Eisenmenger syndrome, due to AVSD progression
• Pulmonary vascular disease, generally noted in those with Down syndrome
• Post-surgical complications

Some children may present lifelong complications following surgical correction of the abnormality.

How is Atrioventricular Septal Defect Treated?

The treatment of Atrioventricular Septal Defect (AVSD) is based on the severity of the presenting signs and symptoms, the type of defects noted, the overall health condition, and other associated medical conditions (if any). Management of the condition involves correcting the defect(s) and providing symptomatic treatment. However, surgery to correct the condition is necessary irrespective of whether AVSD is partial or complete.

The treatment measures include:

• Medications to address the symptoms and complications, until children can tolerate surgery
• Children who have feeding difficulties may be recommended specialized high-calorie formulas or even the insertion of a feeding tube
• Surgery to correct the defect(s) - closure of the septal wall holes (using patches) and valve reconstruction/repair, as needed
  • Children with a complete AVSD may undergo surgery within 3-6 months
  • Children with a partial AVSD may undergo surgery within 6-18 months
• Medications to help the child heal post-surgery
• Regular health check-ups are essential

Taking steps to maintain a healthy heart after the surgery is important. This may be accomplished by:  

• Avoidance of smoking
• Avoiding high-fat diets (to prevent obesity)
• Limiting alcohol consumption
• Exercising regularly (per advise of the physician)
• Having a healthy diet
• Managing stress

How can Atrioventricular Septal Defect be Prevented?

Presently, there are no available guidelines to prevent Atrioventricular Septal Defect.

• Detecting early signs and symptoms combined with a timely diagnosis, holds the key to managing the disorder
• Identifying other accompanying heart ailments and preventing further complications
• Avoid non-prescriptive medications during pregnancy that may harm the fetus
• Folic acid intake: Tests and researches have proved that sufficient intake of folic acid decreases the risk for birth defects

Regular medical screening at periodic intervals with tests, scans, and physical examinations are mandatory for those who have already undergone surgical correction of the defect. Often, several years of active vigilance may be necessary.

What is the Prognosis of Atrioventricular Septal Defect? (Outcomes/Resolutions)

The prognosis of Atrioventricular Septal Defect (AVSD) is generally good with adequate (surgical) treatment, but it depends on the severity of AVSD, overall health of the child, and the presence of any other underlying heart/lung condition.

• A late recognition of the condition and lack of appropriate treatment may lead to complications and adverse outcomes
• After AVSD has been surgically corrected, a healthy life can be normally expected

Additional and Relevant Useful Information for Atrioventricular Septal Defect:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/heart-center/