Note: To view the atrioventricular canal defect animation, you need the latest version of Adobe Flash Player.
Complete Common Atrioventricular Canal Defect, also known as Atrioventricular Septal Defect, is a lack of separation of the atria and the ventricles into separate right and left chambers as well as a lack of separation of the mitral and tricuspid valves. The lack of separation of these two valves results in a single atrioventricular valve.
In patients with atrioventricular canal defect, the single atrioventricular may not close properly. Therefore, the heart must pump an excessive amount of blood and this may result in an enlargement of the heart.
Surgical repair for atrioventricular canal defect is required within the first six months of life. The surgery involves sewing patches over the ASD and VSD and carefully separating the single atrioventricular valve into two valves.
How Does Atrioventricular Canal Defect Differ From
Normal Cardiac Anatomy?
If your child has atrioventricular canal defect the structure of his or her heart is different from normal cardiac anatomy.
Heart With Normal Cardiac Anatomy
Note: To view heart animations, you need the latest version of the
Adobe Flash Player.
When your child has a congenital heart defect, there's usually something wrong with the structure of his or her heart's structure.
The heart is composed of four chambers. The two upper chambers, known as atria, collect blood as it flows back to the heart. The two lower chambers, known as ventricles, pump blood with each heartbeat to the two main arteries (the pulmonary artery and the aorta). The septum is the wall that divides the heart into right and left sides. The atrial septum separates the right and left atria; likewise, the ventricular septum separates the two ventricles.
There are four valves that control the flow of blood through the heart. These flap-like structures allow blood to flow in only one direction. The tricuspid and mitral valves, also known as the atrioventricular valves, separate the upper and lower chambers of the heart. The aortic and pulmonary valves, also known as the arterial valves, separate the ventricles from the main arteries. Oxygen-depleted blood returns from the body and drains into the right atrium via the superior and inferior vena cavas. The blood in the right atrium then passes through the tricuspid valve and enters the right ventricle.
Next, the blood passes through the pulmonary valve, enters the pulmonary artery, and travels to the lungs where it is replenished with oxygen. The oxygen-rich blood returns to the heart via the pulmonary veins, draining into the left atrium. The blood in the left atrium passes through the bicuspid, or mitral, valve and enters the left ventricle.
Finally, the oxygen-rich blood flows through the aortic valve into the aorta and out to the rest of the body.
From Nemours' KidsHealth
- ECG (Electrocardiogram)
- Cardiac Catheterization
- A to Z: Hypoplastic Left Heart Syndrome
- A to Z: Atrial Flutter
- Atrial Septal Defect
- If Your Child Has a Heart Defect
- When Your Child Needs a Heart Transplant
- A to Z: Tetralogy of Fallot
- Tetralogy of Fallot
- A to Z: Patent Ductus Arteriosus (PDA)
- Heart Murmurs and Your Child
- Patent Ductus Arteriosus (PDA)
- Coarctation of the Aorta
- Congenital Heart Defects
- Heart and Circulatory System
- Congenital Heart Defects Special Needs Factsheet
- Ventricular Septal Defect
Trusted External Resources
An electrocardiogram (ECG or EKG) measures the heart's electrical activity. This can help doctors tell how the heart is working and identify any problems.
The ECG can help show the rate and regularity of heartbeats, the size and position of the heart's chambers, and whether there is any damage.
How Is an ECG Done?
There is nothing painful about getting an ECG. The patient is asked to lie down, and small metal tabs (called electrodes) are fixed to the skin with sticky papers. These electrodes are placed in a standard pattern on the shoulders, the chest, the wrists, and the ankles.
After the electrodes are in place, the person is asked to hold still and, perhaps, to hold his or her breath briefly while the heartbeats are recorded for a short period. The patient also might be asked to get up and exercise for a while.
The information is interpreted by a machine and drawn as a graph. The graph shows multiple waves, which reflect the activity of the heart. The height, length, and frequency of the waves are read in the following way:
- The number of waves per minute on the graph is the heart rate.
- The distances between these waves is the heart rhythm.
- The shapes of the waves show how well the heart's electrical impulses are working, the size of the heart, and how well the individual parts of the heart are working together.
- The consistency of the waves provides fairly specific information about any heart damage.
What Can an ECG Diagnose?
A person's heartbeat should be consistent and even. ECGs look for abnormally slow and fast heart rates, abnormal rhythm patterns, conduction blocks (short-circuits of the heart's electrical impulses that cause rhythm inconsistencies between the upper and lower chambers) — and four types of heart damage:
- ventricular hypertrophy — an abnormal thickening of the heart muscle
- ischemia — caused by an abnormally decreased blood supply
- cardiomyopathies — abnormalities in the heart muscle itself
- electrolyte and drug disturbances — these can change the heart's electrochemical environment
Computerized ECGs can be used with other tests to get a multimedia account of the heart. These other tests include echocardiograms (which are basically "ultrasound" tests that bounce sound off the heart and use the echoes to make an image) and thallium scans (which are kind of like X-rays and use a radioactive tracer, injected into the bloodstream, to help draw a picture of the heart).
In the past, the ECG was recorded on a machine that drew on long strips of paper, with records from each electrode presented in a standard sequence. Now the ECG tracings are stored as computer files that can be called up and printed.
When Are Results Ready?
Results of the ECG are available immediately. In fact, the ECG machine's computer even provides an instant interpretation of the findings as it makes the report. However, the doctor also might ask an expert, usually a cardiologist, to help analyze and interpret the ECG. Some of the ECG results may be subtle, requiring an expert eye to detect them.
Reviewed by: Steven Dowshen, MD
Date reviewed: April 28, 2017