Atrioventricular Septal Defect (AVSD) also known as atrioventricular canal defect or endocardial cushion defect, is a severe congenital heart condition that affects the structure and function of the heart. Although it is often diagnosed in infancy or early childhood, advances in cardiology have aided many patients to live healthy lives with appropriate treatment.
Atrioventricular Septal Defect is a congenital heart defect characterised by a hole between the heart's chambers and abnormalities in the valves that control blood flow between these chambers. This results in the mixing of oxygen-rich and oxygen-poor blood, causing the heart to work harder than usual.
AVSD primarily affects the heart's centre, where the walls separating the heart's chambers (the atria and ventricles) meet and where the atrioventricular valves (mitral and tricuspid) are located.
Expert Insight: Yale Medicine explains that in an atrioventricular septal defect, the heart valves don't form correctly, potentially leading to abnormal blood leakage.
In this form, there is a large hole in the heart's centre, and a single standard atrioventricular valve instead of two separate valves. It is often associated with Down syndrome.
A smaller hole exists, usually in the atrial septum, and the two valves are present but abnormally formed. This form may not be diagnosed until later in childhood or even adulthood.
Features of both partial and complete AVSDs are present, but the valves are more separate than in the full form.
AVSDs occur during fetal development when the heart fails to form correctly. The exact cause is often unknown, but several risk factors have been identified:
Symptoms depend on the size and type of the defect and can vary significantly between individuals.
Due to the structural defects, blood flows abnormally within the heart, leading to increased blood volume in the lungs and overwork of the heart muscle. Over time, this can result in:
Fetal echocardiography can sometimes detect AVSD during routine ultrasounds, especially if the fetus is at risk (e.g., has Down syndrome).
A doctor may detect a murmur or other abnormal heart sounds, prompting further evaluation.
AVSD typically requires surgical correction. The timing and type of surgery depend on the severity of the defect and the child's health.
Medications may be used to control symptoms before surgery:
Surgery is usually performed in the first 6-12 months of life for complete AVSD, and later for partial AVSD if symptoms are mild.
Surgical techniques include:
Treatment Insight: Cincinnati Children's Hospital explains that corrective heart surgery is necessary in all cases of AVSD
Approximately 40% of children with Down syndrome have congenital heart defects, with AVSD being the most common. Early intervention and surgery significantly improve outcomes in this population.
Study Highlight: The National Down Syndrome Society states that Atrioventricular Septal Defect (AVSD) is the most frequently observed congenital heart condition in children with Down syndrome. This emphasises the strong correlation between the two conditions.
Without treatment, AVSD can lead to:
Recent innovations include:
According to the AHA and the American College of Cardiology:
Atrioventricular Septal Defect is a serious but treatable congenital heart condition. With early diagnosis, expert surgical care, and lifelong follow-up, most individuals with AVSD can thrive. Our heart clinic offers specialised care for congenital heart defects, guided by compassion, expertise, and the latest medical science.
If you or your child has been diagnosed with AVSD, we are here to help every step of the way. Schedule a consultation with our cardiologists today to learn more about your options and start your journey toward better heart health.
This write-up has been medically reviewed by Dr. Michael Ross MacDonald, a consultant cardiologist at The Harley Street Heart & Vascular Centre in Singapore, to ensure the accuracy and reliability of the information provided.