Atrioventricular Canal Defect – Symptoms and Causes

Understanding Atrioventricular Heart Defects

Atrioventricular heart defects are serious congenital conditions present at birth that affect the center of the heart. These defects include holes between heart chambers and valve problems that disrupt normal blood flow patterns.

When a child has this condition, extra blood flows to the lungs, forcing the heart to work harder than normal. This extra strain causes the heart muscle to enlarge over time.

Without proper treatment, these defects can lead to heart failure and pulmonary hypertension (high blood pressure in the lungs).

Medical professionals may refer to this condition by several names:

• Atrioventricular septal defect (AVSD)
• Endocardial cushion defect

Treatment typically involves surgical repair during the baby’s first year of life. During surgery, doctors close the hole between chambers and fix the affected valves. This helps restore normal blood flow through the heart.

Signs and Symptoms

Complete Heart Opening

When a person has a complete heart opening defect, all four chambers of the heart are affected. Symptoms usually appear within the first few weeks after birth. These symptoms resemble heart failure and may include:

• Bluish or grayish skin coloration (due to oxygen shortage)
• Breathing difficulties or rapid breathing
• Excessive sweating
• Feeling tired often
• Fast or irregular heartbeat
• Poor feeding
• Slow weight gain
• Swelling in lower body parts (feet, ankles, legs)
• Wheezing sounds when breathing

Babies with complete defects often need medical attention quickly as their symptoms can be serious.

Partial Heart Opening

With a partial heart opening defect, only the upper two chambers of the heart are affected. People might not notice any symptoms until they reach early adulthood.

These symptoms often develop because of related problems like valve issues, lung blood pressure problems, or heart failure. Common signs include:

• Feeling tired and weak
• Upset stomach and reduced appetite
• Ongoing cough or wheezing
• Heartbeat that’s too fast or irregular (arrhythmia)
• Less ability to exercise
• Trouble breathing, especially during activity
• Swelling in the legs, ankles, and feet
• Pressure or pain in the chest

People with partial defects may live many years before symptoms become noticeable enough to seek medical help.

What Causes Heart Passage Problems

How Your Heart Functions

The heart is a muscle that pumps blood throughout your body. It works constantly, moving blood to pick up oxygen from the lungs and deliver it to all parts of the body.

This process happens automatically without you having to think about it.

Your heart beats about 100,000 times each day. With each beat, it pushes blood forward through a series of chambers and vessels. This ensures oxygen and nutrients reach every cell in your body.

Heart Sections and Doorways

Your heart has four main sections. The top two sections are called atria, and they receive blood coming into the heart. The bottom two sections are called ventricles, which are stronger and pump blood out to your body and lungs.

Between these sections are special doorways called valves. These valves:

• Open to let blood flow forward
• Close to prevent blood from going backward
• Keep blood moving in the right direction
• Work like one-way gates in the heart

What Goes Wrong in Heart Passage Defects

When someone has a partial heart passage defect:

• A hole exists between the upper heart sections
• The valves between chambers don’t form correctly
• These improperly formed valves can’t close completely
• Blood flows in wrong directions through leaky valves
• Usually the valve on the left side has the most problems

In a complete heart passage defect, more serious problems occur:

1. A large hole forms in the center of the heart.
2. This hole connects both upper and lower sections.
3. Oxygen-rich and oxygen-poor blood mix together.
4. Instead of separate valves, one large irregular valve forms.
5. Blood leaks through this abnormal valve.

These problems force the heart to work harder than normal, causing it to enlarge over time.

Heart Passage Abnormalities

Heart passage defects develop before birth while a baby’s heart is still forming. Doctors aren’t certain exactly why these defects happen in some babies. Having Down syndrome increases the chance of being born with this heart problem.

These defects can be partial or complete. Partial defects mainly affect the upper chambers, while complete defects involve all four heart chambers. The severity depends on how much of the heart’s structure is affected and how much blood flows incorrectly.

Risk Factors

Several factors may raise the chance of having an atrioventricular canal defect:

• Family history and genetics play an important role. Heart problems often run in families. Children with Down syndrome have a higher chance of being born with heart defects.
• Infections during pregnancy, especially German measles (rubella), can affect how a baby’s heart forms.
• Health conditions like poorly controlled diabetes in pregnant women can impact heart development. However, gestational diabetes usually doesn’t increase this risk.
• Substance use during pregnancy increases risks:
  • Alcohol consumption
  • Smoking tobacco
• Medication exposure while pregnant may lead to heart problems. Always tell your doctor about any medications you take.

These risk factors don’t always cause heart defects. Many babies with these defects are born to mothers with no known risk factors.

Possible Health Issues

Individuals who have undergone surgery for atrioventricular canal defect before any permanent lung damage occurred often can have successful pregnancies. However, pregnancy is not advised for those who experienced serious heart or lung damage before their corrective surgery.

It’s essential to consult with an adult congenital cardiologist before becoming pregnant. This specialist can:

• Evaluate your specific heart condition
• Discuss potential risks and complications
• Create a specialized care plan for your pregnancy

Common complications without treatment include:

Complication	Description
Enlarged heart	Extra blood flow makes the heart work harder and grow larger
Lung high blood pressure	Too much blood flows to the lungs, building pressure
Repeated lung infections	The heart defect can lead to ongoing respiratory problems
Heart failure	Without treatment, the heart cannot pump enough blood

Even with successful treatment, some problems may develop later:

• Breathing difficulties from lung damage
• Abnormal heart rhythms
• Leaky heart valves
• Narrowed heart valves

Prevention

No known prevention exists for atrioventricular canal defect. Some heart problems run in families. If you or your family members have congenital heart disease, speak with a genetic counselor and a cardiologist before planning a pregnancy.