Arrhythmia

An arrhythmia (ah-RITH-me-ah) is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm.

A heartbeat that is too fast is called tachycardia (TAK-ih-KAR-de-ah). A heartbeat that is too slow is called bradycardia (bray-de-KAR-de-ah).

Most arrhythmias are harmless, but some can be serious or even life threatening. When the heart rate is too fast, too slow, or irregular, the heart may not be able to pump enough blood to the body. Lack of blood flow can damage the brain, heart, and other organs.

To understand arrhythmias, it helps to understand the heart's internal electrical system. The heart's electrical system controls the rate and rhythm of the heartbeat.

With each heartbeat, an electrical signal spreads from the top of the heart to the bottom. As the signal travels, it causes the heart to contract and pump blood. The process repeats with each new heartbeat.

Each electrical signal begins in a group of cells called the sinus node or sinoatrial (SA) node. The SA node is located in the right atrium (AY-tree-um), which is the upper right chamber of the heart. In a healthy adult heart at rest, the SA node fires off an electrical signal to begin a new heartbeat 60 to 100 times a minute.

From the SA node, the electrical signal travels through special pathways in the right and left atria. This causes the atria to contract and pump blood into the heart's two lower chambers, the ventricles (VEN-trih-kuls).

The electrical signal then moves down to a group of cells called the atrioventricular (AV) node, located between the atria and the ventricles. Here, the signal slows down just a little, allowing the ventricles time to finish filling with blood.

The electrical signal then leaves the AV node and travels along a pathway called the bundle of His. This pathway divides into a right bundle branch and a left bundle branch. The signal goes down these branches to the ventricles, causing them to contract and pump blood out to the lungs and the rest of the body.

The ventricles then relax, and the heartbeat process starts all over again in the SA node.

A problem with any part of this process can cause an arrhythmia. For example, in atrial fibrillation, a common type of arrhythmia, electrical signals travel through the atria in a fast and disorganized way. This causes the atria to quiver instead of contract.

There are many types of arrhythmia. Most arrhythmias are harmless, but some are not. The outlook for a person who has an arrhythmia depends on the type and severity of the arrhythmia.

Even serious arrhythmias often can be successfully treated. Most people who have arrhythmias are able to live normal, healthy lives.

Signs and Symptoms

Many arrhythmias cause no signs or symptoms. When signs or symptoms are present, the most common ones are:

• Palpitations (feelings that your heart is skipping a beat, fluttering, or beating too hard or fast)
  
• A slow heartbeat
  
• An irregular heartbeat
  
• Feeling pauses between heartbeats

More serious signs and symptoms include:

• Anxiety
  
• Weakness, dizziness, and lightheadedness
  
• Fainting or nearly fainting
  
• Sweating
  
• Shortness of breath
  
• Chest pain

Diagnosis

Arrhythmias can be hard to diagnose, especially the types that only cause symptoms every once in a while. Doctors use several methods to help diagnose arrhythmias, including medical and family histories, physical exam, and diagnostic tests and procedures.

Specialists Involved Doctors who specialize in the diagnosis and treatment of heart diseases include: Cardiologists. These doctors take care of adults who have heart problems. Pediatric cardiologists. These doctors take care of babies, children, and youth who have heart problems. Electrophysiologists. These doctors are cardiologists or pediatric cardiologists who specialize in arrhythmias.

Medical and Family Histories

To diagnose an arrhythmia, your doctor may ask about your signs and symptoms. He or she may ask about what symptoms you're having, whether you feel fluttering in your chest, and whether you feel dizzy or lightheaded.

Your doctor also may ask about other health problems you have, such as a history of heart disease, high blood pressure, diabetes, or thyroid problems. He or she may ask about your family' s medical history, including:

• Does anyone in your family have a history of arrhythmias?
  
• Has anyone in your family ever had heart disease or high blood pressure?
  
• Has anyone in your family died suddenly?
  
• Are there other illnesses or health problems in your family?

Your doctor will likely want to know what medicines you're taking, including over-the-counter medicines and vitamin or mineral or nutritional supplements.

Your doctor may ask about your health habits, such as physical activity, smoking, or using alcohol or drugs (for example, cocaine). He or she also may want to know whether you've had episodes of strong emotional stress or anger.

Physical Exam

Your doctor will listen to the rate and rhythm of your heart and for a heart murmur (an extra or unusual sound heard during your heartbeat). He or she also will:

• Check your pulse to find out how fast your heart is beating
  
• Check for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
  
• Look for signs of other diseases, such as thyroid disease, that could be causing the problem

Diagnostic Tests and Procedures

EKG (Electrocardiogram)

An EKG is the most common test used to diagnose arrhythmias. An EKG is a simple test that detects and records the heart's electrical activity.

The test shows how fast the heart is beating and its rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through each part of the heart.

A standard EKG only records the heartbeat for a few seconds. It won't detect arrhythmias that don't happen during the test.

To diagnose arrhythmias that come and go, your doctor may have you wear a portable EKG monitor. The two most common types of portable EKGs are Holter and event monitors.

Holter and Event Monitors

A Holter monitor records the heart's electrical signals for a full 24- or 48-hour period. You wear one while you do your normal daily activities. This allows the monitor to record your heart for a longer time than a standard EKG.

An event monitor is similar to a Holter monitor. You wear an event monitor while doing your normal activities. However, an event monitor only records your heart's electrical activity at certain times while you're wearing it.

For many event monitors, you push a button to start the monitor when you feel symptoms. Other event monitors start automatically when they sense abnormal heart rhythms.

Some event monitors are able to send data about your heart's electrical activity to a central monitoring station. Technicians at the station review the information and send it to your doctor. You also can use the device to report any symptoms you're having.

You may wear an event monitor for 1 to 2 months, or as long as it takes to get a recording of your heart during symptoms.

Other Tests

Other tests also are used to help diagnose arrhythmias.

Blood tests. Blood tests check the level of substances in the blood, such as potassium or thyroid hormone, that can increase your chances of having an arrhythmia.

Chest x ray. A chest x ray is a painless test that creates pictures of the structures in your chest, such as your heart and lungs. This test can show whether the heart is enlarged.

(EK-o-kar-de-OG-ra-fee). This test uses sound waves to create a moving picture of your heart. Echocardiography (echo) provides information about the size and shape of your heart and how well your heart chambers and valves are working.

The test also can identify areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by poor blood flow.

There are several different types of echo, including stress echo. This test is done both before and after a stress test (see below). A stress echo usually is done to find out whether you have decreased blood flow to your heart, a sign of coronary heart disease (CHD).

A transesophageal (tranz-ih-sof-uh-JEE-ul) echo, or TEE, is a special type of echo that takes pictures of the back of the heart through the esophagus (the passage leading from your mouth to your stomach).

Stress test. Some heart problems are easier to diagnose when your heart is working hard and beating fast. During stress testing, you exercise (or are given medicine if you're unable to exercise) to make your heart work hard and beat fast while heart tests are done.

These tests may include nuclear heart scanning, echocardiography, and magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning of the heart.

Electrophysiology study (EPS). This test is used to assess serious arrhythmias. During an EPS, a thin, flexible wire is passed through a vein in your groin (upper thigh) or arm to your heart. The wire records the heart's electrical signals.

Your doctor uses the wire to electrically stimulate your heart and trigger an arrhythmia. This allows the doctor to see whether an antiarrhythmia medicine can stop the problem.

Catheter ablation, a procedure used to fix some types of arrhythmia, may be done during an EPS.

Tilt table testing. This test sometimes is used to help find the cause of fainting spells. You lie on a table that moves from a lying down to an upright position. The change in position can cause you to faint.

Your doctor watches your symptoms, heart rate, EKG reading, and blood pressure throughout the test. Your doctor also may give you medicine and then check your response to the medicine.

Coronary angiography (an-jee-OG-ra-fee). Coronary angiography uses dye and special x rays to show the inside of your coronary (heart) arteries.

During the test, a long, thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck.

The tube is then threaded into your coronary arteries, and the dye is injected into your bloodstream. Special x rays are taken while the dye is flowing through the coronary arteries.

The dye lets your doctor study the flow of blood through your heart and blood vessels. This helps your doctor find blockages that can cause a heart attack.

Implantable loop recorder. This device detects abnormal heart rhythms. Minor surgery is used to place this device under the skin in the chest area.

An implantable loop recorder helps doctors figure out why a person may be having palpitations or fainting spells, especially when these symptoms don’t happen very often. The device can be used for as long as 12 to 24 months.

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Treatment

Common arrhythmia treatments include medicines, medical procedures, and surgery. Treatment is needed when an arrhythmia causes serious symptoms, such as dizziness, chest pain, or fainting.

Treatment also is needed if an arrhythmia increases your risk for complications, such as heart failure, stroke, or sudden cardiac arrest.

Medicines

Medicines can be used to speed up a heart that’s beating too slow or slow down a heart that’s beating too fast. They also can be used to convert an abnormal heart rhythm to a normal, steady rhythm. Medicines that do this are called antiarrhythmics.

Some of the medicines used to slow a fast heart rate are beta blockers (such as metoprolol and atenolol), calcium channel blockers (such as diltiazem and verapamil), and digoxin (digitalis). These medicines often are used to slow the heart rate in people who have atrial fibrillation.

Some of the medicines used to restore an abnormal heartbeat to a normal rhythm are amiodarone, sotalol, flecainide, propafenone, dofetilide, ibutilide, quinidine, procainamide, and disopyramide. These medicines often have side effects. Some of the side effects can make an arrhythmia worse or even cause a different kind of arrhythmia.

People who have atrial fibrillation and some other arrhythmias often are treated with anticoagulants, or blood thinners, to reduce the risk of blood clots forming. Aspirin, warfarin (Coumadin®), and heparin are commonly used blood thinners.

Medicines also can control an underlying medical condition, such as heart disease or a thyroid condition, that might be causing an arrhythmia.

Medical Procedures

Some arrhythmias are treated with a pacemaker. A pacemaker is a small device that's placed under the skin of your chest or abdomen to help control abnormal heart rhythms.

This device uses electrical pulses to prompt the heart to beat at a normal rate. Most pacemakers contain a sensor that activates the device only when the heartbeat is abnormal.

Some arrhythmias are treated with a jolt of electricity delivered to the heart. This type of treatment is called cardioversion or defibrillation, depending on which type of arrhythmia is being treated.

Some people who are at risk for ventricular fibrillation are treated with a device called an implantable cardioverter defibrillator (ICD). Like a pacemaker, an ICD is a small device that’s placed under the skin in the chest. This device uses electrical pulses or shocks to help control life-threatening arrhythmias.

An ICD continuously monitors the heartbeat. If it senses a dangerous ventricular arrhythmia, it sends an electric shock to the heart to restore a normal heartbeat.

A procedure called catheter ablation is sometimes used to treat certain types of arrhythmia when medicines don’t work.

During this procedure, a long, thin, flexible tube is put into a blood vessel in your arm, groin (upper thigh), or neck. The tube is guided to your heart through the blood vessel. A special machine sends energy through the tube to your heart.

This energy finds and destroys small areas of heart tissue where abnormal heartbeats may cause an arrhythmia to start. Catheter ablation usually is done in a hospital as part of an electrophysiology study.

Surgery

Sometimes, an arrhythmia is treated with surgery. This often occurs when surgery is already being done for another reason, such as repair of a heart valve.

One type of surgery for atrial fibrillation is called "maze" surgery. In this operation, the surgeon makes small cuts or burns in the atria that prevent the spread of disorganized electrical signals.

If coronary heart disease is causing arrhythmias, coronary artery bypass grafting may be recommended. This surgery improves blood supply to the heart muscle.

Other Treatments

Vagal maneuvers are another arrhythmia treatment. These simple exercises sometimes can stop or slow down certain types of supraventricular arrhythmias. They do this by affecting the vagus nerve, which helps control the heart rate.

Some vagal maneuvers include:

• Gagging
  
• Holding your breath and bearing down (Valsalva maneuver)
  
• Immersing your face in ice-cold water
  
• Coughing
  
• Putting your fingers on your eyelids and pressing down gently

Vagal maneuvers aren't an appropriate treatment for everyone. Discuss with your doctor whether vagal maneuvers are an option for you.

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