Ebstein's Anomaly

Heart With Ebstein's Anomaly

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Ebstein's Anomaly is a rare defect, accounting for less than 1 percent of all congenital heart defects. The principal aberration occurring with Ebstein's Anomaly is a malformation of the tricuspid valve, which is located between the right atrium and right ventricle. Two of the three leaflets of the valve (the septal leaflet and the posterior leaflet) are displaced downward into the right ventricular cavity. These valve leaflets vary from mildly deformed to severely deformed. The third leaflet (the anterior leaflet) is not displaced but is typically large and redundant, often described as "sail-like". The portion of the right ventricle that sits above the displaced leaflets is usually thinner than normal and may be referred to as the atrialized portion of the right ventricle. A hole between the upper chambers of the heart, either an atrial septal defect or a patent foramen ovale, is virtually always present in association with Ebstein's anomaly. In some patients with this malformation, the pulmonary valve is also abnormal, either abnormally tight (pulmonary valve stenosis) or entirely closed (pulmonary valve atresia).

Most commonly, the deformed tricuspid valve has a tendency to leak, thus, as the right ventricle contracts some blood flows backwards from the right ventricle to the right atrium. Because of this backwards leakage of blood, a reduced volume of blood enters the right ventricle to be ejected to the lungs. The right atrium, which receives this leaking blood, is usually quite enlarged. Some of the blue blood from the right atrium may pass across the hole in the atrial septum into the left atrium. This blue blood then goes directly out to the body, which may be recognized as cyanosis in the patient. This is frequently present in newborns with Ebstein's anomaly and usually improves over the first weeks of life.

Infrequently, the deformed tricuspid valve forms an imperforate membrane. In this setting, rather than leaking, the tricuspid valve blocks blood from advancing into the right ventricle and out to the lungs.

In patients where the degree of valve deformity is mild and no symptoms are present, no intervention may be required other than prescribing antibiotics prior to dental or surgical procedures to prevent bacterial endocarditis. In patients with more severe involvement, cyanosis, shortness of breath, exercise intolerance and/or significant heart enlargement are often present and surgical intervention is warranted. The surgery usually consists of repairing or replacing the abnormal tricuspid valve and closing the hole between the atria.


What Is Normal Cardiac Anatomy?

When your child has a congenital heart defect, there's usually something wrong with the structure of his or her heart's structure.

 
Learn More About Normal Cardiac Anatomy

Heart With Normal Cardiac Anatomy

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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.

Arrhythmias

An arrhythmia  is an abnormal heart rhythm. Most arrythmias are caused by an electrical "short circuit" in the heart.

The heart normally beats in a consistent pattern, but an arrhythmia can make it beat too slowly, too quickly, or irregularly. This erratic pumping can lead to a variety of symptoms, including fatigue, dizziness, and chest pain.

Many arrhythmias don't need medical care, but some can pose a health problem and need to be evaluated and treated by a doctor.

What Causes Arrhythmias?

A unique electrical conduction system in the heart causes it to beat in its regular rhythm. 

The electrical signals start from a group of cells called the sinus node, located in the right atrium. The sinus node acts as the heart's pacemaker and makes sure the heart is beating at a normal and consistent rate. The sinus node normally speeds up the heart rate in response to things like exercise, emotions, and stress, and slows the heart rate during sleep.

But sometimes the electrical signals don't "communicate" properly with the heart muscle, and the heart can start beating in an abnormal rhythm — this is an arrhythmia (also called dysrhythmia).

Arrhythmias also can be due to chemical imbalances in the blood; infections; diseases that irritate the heart; medicines (prescription, over-the-counter, and some herbal remedies); injuries to the heart from chest trauma or heart surgery; use of illegal drugs, alcohol, or tobacco; caffeine; and stress.

Arrhythmias can be temporary or permanent. An arrhythmia can be congenital (meaning a baby is born with it) or happen later.

Signs and Symptoms

Arrhythmias make the heart beat less effectively, interrupting blood flow to the brain and the rest of the body. When the heart beats too fast, its chambers can't fill with enough blood. When it beats too slowly or irregularly, it can't pump enough blood out to the body.

If the body doesn't get the supply of blood it needs to run smoothly, a person might have:

  • dizziness
  • fatigue
  • lightheadedness
  • weakness
  • palpitations (a feeling of fluttering or pounding in the chest)
  • shortness of breath
  • chest pain
  • fainting

Arrhythmias can be constant, but most come and go at random. Some cause no detectable symptoms at all. In these cases, the arrhythmia is only found during a physical examination or a heart function test.

What's a Normal Heart Rate?

Heart rate is measured by counting the number of beats per minute. Someone's normal heart rate depends on things like the person's age and whether he or she leads an active lifestyle. 

The resting heart rate decreases as kids get older. Typical normal resting heart rate ranges are:

  • babies (birth to 3 months of age): 100–150 beats per minute
  • kids 1–3 years old: 70–110 beats per minute
  • kids by age 12: 55–85 beats per minute

A doctor can determine whether a heart rate is abnormally fast or slow, depending on a person's situation. An older child or adult with a slow heart rate, for example, might have symptoms when the heart rate drops below 50 beats per minute. But trained athletes have a lower resting heart rate, so a slow heart rate in them isn't considered abnormal if it causes no symptoms.

Types of Arrhythmias

There are several types of arrhythmias, including:

Premature Atrial Contraction (PAC) and Premature Ventricular Contraction (PVC)

Premature contractions are usually considered minor arrhythmias. The person may feel a fluttering or pounding in the chest caused by an early or extra beat. PACs and PVCs are very common, and are what happens when it feels like your heart "skips" a beat. Actually, the heart doesn't skip a beat — an extra beat comes sooner than normal. Occasional premature beats are common and considered normal, but in some cases they can be a sign of an underlying medical problem or heart condition.

Tachycardias

A tachycardia is an abnormally fast heartbeat. Tachycardias fall into two major categories — supraventricular and ventricular:

  • Supraventricular tachycardia (SVT) is characterized by bursts of fast heartbeats that start in the upper chambers of the heart. These can happen suddenly and last anywhere from a few seconds to several days. Treatment is usually recommended if SVTs are long-lasting or happen often.
  • Ventricular tachycardia is a serious but uncommon condition that starts in the lower chambers of the heart and can be dangerous.

Bradycardias

A bradycardia is an abnormally slow heartbeat. Bradycardias can be due to:

  • Sinus node dysfunction, when the heart's sinus node isn't working correctly, usually after surgery to correct a congenital heart defect.
  • Heart block, when electrical impulses can't make their way from the upper to lower chambers of the heart. It's often caused by a congenital heart defect, but also can be due to disease or injury.

Diagnosing Arrhythmias

Doctors use several tools to diagnose arrhythmias. It's very important to know a child's medical history and give this information to the doctor. The doctor will use the medical history, along with a physical exam, to begin the evaluation.

If an arrhythmia is suspected, the doctor will order an electrocardiogram (EKG) to measure the heart's electrical activity. For this painless test, the child will lie down and have small metal tabs (called electrodes) fixed to the skin with sticky papers. The electrodes have wires attached to them, which connect to the EKG machine. The electrical signals from the heart are then briefly recorded, usually for just 10 seconds. This information is sent to a computer, where it's interpreted and drawn as a graph.

These types of EKG tests might be recommended:

  • Resting EKG. This measures resting heart rate and rhythm, and lasts about a minute.
  • Exercise EKG (also called a stress test). This measures heart rate and rhythm during exercising, like riding a stationary bicycle or walking on a treadmill.
  • Signal-average EKG. This is much like a resting EKG, but monitors the heartbeat for about 15–20 minutes.
  • Holter monitor. This EKG is done over a long period of time, usually 24 hours or more. The electrodes are fixed to the chest, and the wires are attached to a portable EKG recorder. The child is encouraged to continue normal daily activities, but must be careful to not get the electrodes wet (for example, no swimming, showering, or activities that cause a lot of sweating).

    The two kinds of Holter monitoring are: continuous recording, which means the EKG is on throughout the entire monitoring period; and event monitoring, which means data is recorded only when the child feels symptoms and then turns the Holter monitor on.

Treating Arrhythmias

Many arrhythmias don't need treatment. For those that do, these options might be used:

  • Medicine. Doctors may prescribe anti-arrhythmic medicines depending on the type of arrhythmia and other considerations. Sometimes, these can increase symptoms and cause side effects, so the patient will be closely watched by the doctor.
  • Pacemakers. A pacemaker is a small battery-operated device implanted into the body (near the collarbone) through a surgical procedure. Connected to the heart by a wire, a pacemaker can detect if the heart rate is too slow and send electrical signals to speed up the heartbeat.
  • Defibrillators. A small battery-operated implantable cardioverter defibrillator (ICD) is surgically placed near the left collarbone. Wires run from the defibrillator to the heart. The ICD senses if the heart has a dangerously fast or irregular rhythm and sends an electrical signal to restore a normal heartbeat.
  • Catheter ablation. A catheter (a long, thin wire) is guided through a vein in the leg to the heart. Arrhythmias often are caused by microscopic defects in the heart muscle. Once the problem area of the heart is pinpointed, the catheter heats or freezes the defective muscle cells and destroys them.
  • Surgery. Surgery is usually recommended only if all other options have failed. The child will be put under anesthesia, and a surgeon will remove the tissue causing the arrhythmia.

When to Call the Doctor

Many arrhythmias are minor and aren't a significant health threat. But some can indicate a more serious problem. If your child has symptoms of an arrhythmia, call your doctor.

Reviewed by: Steven B. Ritz, MD, MSEd
Date reviewed: September 05, 2017