Atrioventricular canal defect (AVCD), also known as atrioventricular septal defect or endocardial cushion defect, is a congenital heart defect that affects the heart’s center. It is characterized by a hole in the wall between the heart’s chambers and abnormalities in the heart valves. These defects cause excessive blood flow to the lungs, overworking the heart, and leading to complications if left untreated.
Types of Atrioventricular Canal Defect
- Partial AVCD:
- Involves a hole in the wall between the upper chambers of the heart (atria).
- Abnormalities in the tricuspid and mitral valves prevent proper closure, allowing blood to flow backward.
- Complete AVCD:
- Affects all four chambers of the heart.
- Features a large central hole where the walls of the heart’s chambers meet.
- Includes one large valve instead of two separate ones, leading to oxygen-rich and oxygen-poor blood mixing.
Symptoms
Symptoms depend on whether the defect is partial or complete:
Complete AVCD (often diagnosed in infancy):
- Rapid or difficulty breathing.
- Bluish or gray skin tone (cyanosis).
- Fatigue and lack of appetite.
- Poor weight gain.
- Irregular or rapid heartbeat.
- Excessive sweating.
- Swelling in the legs, feet, or abdomen.
- Wheezing.
Partial AVCD (symptoms may appear in adulthood):
- Shortness of breath, especially with exertion.
- Fatigue and weakness.
- Irregular heart rhythms (arrhythmias).
- Persistent cough or wheezing.
- Swelling in the legs, ankles, or feet.
- Chest pain or pressure.
Causes
Atrioventricular canal defect occurs during fetal development when the heart doesn’t form properly. While the exact cause is often unknown, several factors may increase the risk, including:
- Genetics: Frequently associated with genetic syndromes such as Down syndrome.
- Maternal infections: Rubella (German measles) during pregnancy can affect heart development.
- Diabetes: Poorly controlled diabetes during pregnancy may contribute.
- Alcohol and smoking: Both are linked to congenital heart defects.
- Certain medications: Some medicines taken during pregnancy may increase the risk.
Complications
If untreated, atrioventricular canal defect can lead to severe complications:
- Heart enlargement: The heart works harder to pump blood, causing it to grow larger.
- Pulmonary hypertension: Increased blood flow to the lungs raises lung pressure, potentially causing long-term damage.
- Respiratory infections: Frequent lung infections may occur due to improper blood flow.
- Heart failure: The heart may struggle to pump enough blood to meet the body’s needs.
- Irregular heart rhythms: Leaky or narrowed valves can cause arrhythmias.
- Lung damage: Permanent damage may occur if the defect isn’t repaired early.
Diagnosis
Diagnosis typically involves the following tests:
- Echocardiogram: Uses sound waves to create images of the heart’s structure and blood flow.
- Electrocardiogram (ECG): Records the heart’s electrical activity.
- Chest X-ray: Identifies heart enlargement or excessive lung blood flow.
- Cardiac catheterization: Provides detailed information about the heart’s function and blood pressure.
Treatment
Surgery is the primary treatment for atrioventricular canal defect, typically performed during the first year of life to prevent complications.
- Surgical Repair:
- Closes the hole between the heart chambers.
- Repairs or reconstructs the heart valves to ensure proper function.
- Medications:
- Used temporarily to manage symptoms like fluid buildup or irregular heart rhythms before surgery.
- Post-Surgery Care:
- Regular follow-ups with a cardiologist to monitor for complications such as valve issues or arrhythmias.
Prognosis
With timely surgical intervention, most children with atrioventricular canal defect lead healthy lives. However, lifelong monitoring is essential to detect and manage potential complications.
Pregnancy Considerations
Women with repaired AVCD and no significant lung or heart damage can often have successful pregnancies. Those with unresolved complications should consult an adult congenital cardiologist to assess risks and plan for specialized care during pregnancy.
Prevention
While AVCD cannot always be prevented, steps to reduce the risk include:
- Preconception counseling: For those with a family history of congenital heart defects, genetic counseling can provide insights.
- Good prenatal care: Includes controlling diabetes, avoiding alcohol and smoking, and ensuring up-to-date vaccinations (e.g., rubella).
- Medication review: Pregnant individuals should consult healthcare providers about the safety of their medications.
By addressing risk factors early, the chances of a healthy pregnancy and reducing congenital heart defects improve.
