Heart defects at birth may affect heart rhythm—even years later

Odds are, you’ve heard of congenital heart defects (CHDs). They’re the most common type of congenital difference—a problem with one or more structures of the heart that develops in the womb and is present when a baby is born. Each year, about 1 percent of children are born with a CHD, according to the Centers for Disease Control and Prevention (CDC). These issues can range from mild to serious. Some may require surgery and could lead to other health problems.

One of these problems is an abnormal heartbeat, called an arrhythmia. When you have an arrhythmia, your heart beats too quickly, too slowly, or in an erratic pattern. Arrhythmias can hinder blood flow to the body. They can damage organs and contribute to a range of potentially life-threatening health conditions, including cardiac arrest and stroke.

People with a CHD are more prone to arrhythmias than people without a CHD. That’s because variations in heart structure and function can influence how the heart beats. Arrhythmias can be caused by a CHD itself or from scarring that forms after surgery to treat a CHD. They may occur at any time in CHD patients—at birth, during childhood, or later in life. Fortunately, healthcare providers (HCPs) may be able to detect and treat these arrhythmias before they become more serious issues.

Risk factors for CHDs

Many CHDs and associated arrhythmias have roots in early pregnancy, when the heart is developing. The exact cause of an individual CHD is often unknown. But gene mutations and chromosomal conditions may be major factors, likely in combination with exposures during pregnancy.

“There are certain commonly used medications pregnant people might take that lead to rhythm disturbance,” says Charles Fuenzalida, MD, an electrophysiologist with Aurora Denver Cardiology Associates in Aurora, Colorado. These medications include statins, ACE inhibitors, thalidomide, an acne drug called isotretinoin, and some drugs used to treat epilepsy and anxiety.

Other possible contributors include having a health condition during pregnancy such as diabetes, rubella, or lupus. Drinking alcohol or smoking during pregnancy increases the risk of CHDs, as well.

Arrhythmias linked to CHDs

There are many kinds of arrhythmias that a person may develop as a result of a CHD. In one kind of arrhythmia, called tachycardia, the heart beats too fast. Tachycardias include, but are not limited to:

• Supraventricular tachycardia (SVT): SVT often starts in the heart’s upper chambers, called the atria. It’s characterized by a sudden, very rapid heartbeat. SVT affects up to 20 percent of adults with a CHD, according to the American College of Cardiology.
• Ventricular tachycardia: Like SVT, ventricular tachycardia is characterized by a faster-than-normal heartbeat. But it starts in the heart’s lower chambers, called the ventricles. It is considered a life-threatening condition and is less common than SVT.
• Atrial fibrillation (AFib) and atrial flutter: These tachycardias begin in the atria and increase the risk of stroke. During atrial fibrillation, the atria beat wildly and out of sync with the ventricles.

In another form of arrhythmia called bradycardia, the heart beats too slowly. Common bradycardias linked to CHDs include:

• Sinus node dysfunction: This commonly occurs after surgery to fix a CHD. The sinus node is often referred to as the heart’s “natural pacemaker” since it keeps the electrical system that regulates heartbeats running smoothly.
• Heart block: This occurs when the heart’s electric signals aren’t able to get from the atria to the ventricles. They’re slowed or entirely blocked.

Another type of arrhythmia is premature or irregular heartbeat. It frequently occurs in young children. It’s typically considered normal and relatively minor, though it can be linked to an underlying CHD or CHD surgery.

Triggers and symptoms of arrhythmia

Arrhythmias are common and may be caused by a range of factors outside of CHDs. In children, these include infections, fevers, and some medications. In adults, arrhythmias can be triggered by anything from stress to an in-progress heart attack.

In both children and adults, many arrhythmias are asymptomatic, meaning they don’t have symptoms. They’re often relatively harmless and may be discovered during a routine physical exam. They may not need treatment.

When there are symptoms, it can indicate a more serious issue. In addition to a slower, faster, or irregular heartbeat, look out for:

• Chest pain
• Weakness
• Dizziness
• Fatigue
• Sweating
• Anxiety
• Heart palpitations, or feeling like the heart is “fluttering” or skipping beats
• Feeling faint or fainting
• Shortness of breath

Children may not be able to articulate exactly how they’re feeling. This can make diagnosing a congenital arrhythmia more difficult. So, in infants and very young children, be aware of general irritability and feeding problems, as well.

If an abnormal heartbeat occurs with any of these symptoms or it keeps going for a long time, reach out to your HCP.

Diagnosis and treatment

The accurate diagnosis of an arrhythmia is important for many reasons. It means treatment for arrhythmia can get started quickly, which can help prevent further complications. It may also help find a potentially dangerous underlying health condition, including a CHD you may not have been aware of.

If your HCP suspects an arrhythmia, they’ll likely get a medical history and perform a physical exam. This can include a blood test to check for infections, medications, or chemical imbalances. The next step is often an electrocardiogram (EKG or ECG), a painless test that measures electrical activity of the heart.

Sometimes, additional testing is necessary. For example, patients may have to wear a Holter monitor over a day or two to record the heart’s electrical activity. They may also need to have an echocardiogram, a type of ultrasound (test that uses soundwaves) that creates a moving image of the heart. Cases involving children may be referred to a pediatric cardiologist, an HCP specializing in kids’ heart conditions.

Treatment for arrhythmia for someone with a CHD hinges on several factors, such as age, the severity of symptoms, and the specific heart defect. Treatment frequently takes one of two paths, notes Dr. Fuenzalida.

“The solution often is to use medications to suppress the irregular heartbeat,” he explains. “The other thing we do is go in and look for signs of irregularity. Then we cauterize it and get rid of it. That’s called an ablation.”

Sometimes, a device like a pacemaker or defibrillator can be implanted to maintain a regular heart rhythm. Surgery isn’t typically recommended unless other treatments fail.

Even after treatment, people born with heart defects require lifelong monitoring and regular visits to a cardiologist. Since some CHDs are hereditary, genetic counseling for prospective parents with CHD is often recommended prior to pregnancy.