Atrioventricular canal

Atrioventricular canal (AV canal), also known as atrioventricular septal defect (AVSD), is a complex congenital heart defect that affects the structure of the heart's chambers and valves. This condition is characterized by a combination of anomalies present at birth that involve the atrial septum, ventricular septum, and one or more of the atrioventricular valves.

Overview

The heart is divided into four chambers: the two upper chambers (atria) and the two lower chambers (ventricles). Normally, the atria are separated from the ventricles by a partition that includes the atrioventricular valves (the mitral valve on the left side of the heart and the tricuspid valve on the right side). In AV canal defect, there is a hole in the center of the heart where the walls between the atria and the ventricles should be. This defect allows oxygen-rich blood from the left side of the heart to mix with oxygen-poor blood from the right side. Additionally, the valves that separate the heart's chambers may not form correctly, leading to leakage.

Types

AV canal defects are classified into two main types:

• Partial AV canal involves a defect in the atrial septum and abnormalities of the atrioventricular valves but the ventricles are usually separated.
• Complete AV canal involves a large hole between the atria and ventricles, and a common atrioventricular valve that crosses the defect, rather than two separate valves.

Symptoms

Symptoms of AV canal defect can vary depending on the severity of the condition and whether other heart defects are present. Common symptoms include:

• Difficulty breathing or rapid breathing
• Fatigue
• Poor weight gain in infants
• Swelling of the legs or abdomen
• Pale or bluish skin color (cyanosis) due to lack of oxygen

Causes

The exact cause of AV canal defect is not fully understood, but it is believed to involve a combination of genetic and environmental factors. This condition is more common in individuals with Down syndrome, suggesting a genetic link.

Diagnosis

Diagnosis of AV canal defect typically involves several tests, including:

• Echocardiogram: An ultrasound of the heart that provides detailed images of its structure and function.
• Electrocardiogram (ECG or EKG): A test that records the electrical activity of the heart.
• Chest X-ray: An imaging test that can show the size and shape of the heart and lungs.
• Cardiac MRI: A detailed imaging test that provides both still and moving pictures of the heart and major blood vessels.

Treatment

Treatment for AV canal defect usually involves surgery to repair the defects. The timing of surgery depends on the severity of the condition and the presence of symptoms. Surgical options include:

• Repair of the atrial and ventricular septal defects
• Reconstruction of the atrioventricular valves to ensure they function properly

Prognosis

With timely and appropriate surgical treatment, most individuals with AV canal defect can lead relatively normal lives. However, they may require lifelong follow-up care with a cardiologist to monitor their heart function and manage any complications.

See also

• Congenital heart defect
• Down syndrome
• Cardiac surgery