• What happens during a normal heart beat?
• What is an arrhythmia?
• What are the common types of arrhythmias?
  • Bradycardia
  • Tachycardia
  • Supraventricular arrhythmias
  • Ventricular arrhythmias
  • Bradyarrhythmias
• What causes an arrhythmia?
• What are the symptoms of an arrhythmia?
• How is an arrhythmia diagnosed?
• How is an arrhythmia treated?

What happens during a normal heart beat?

The heart's electrical system

The heart’s rhythm is coordinated by its own electrical system.

With each heartbeat, the electrical impulse begins at the sinus (or sinoatrial, SA) node, also called the heart’s natural pacemaker. The SA node is a cluster of specialized cells, located in the right atrium. The SA node produces the electrical impulses that set the rate and rhythm of your heartbeat. The impulse spreads through the walls of the right and left atria, causing them to contract, forcing blood into the ventricles.

The impulse then reaches the atrioventricular (AV) node, which acts as an electrical bridge allowing impulses to travel from the atria to the ventricles. There is a short delay before the impulse travels on to the ventricles.

From the AV node, the impulse travels through a pathway of fibers called the HIS-Purkinje system. This network sends the impulse into the  muscular walls of the ventricles and causes them to contract.  This  contraction forces blood out of the heart to the lungs and body.

The SA node fires another impulse and the cycle begins again.

The heartbeat is triggered by electrical impulses that travel down a special pathway through your heart muscle.

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What is my pulse?
Your pulse indicates your heart rate, or the number of times your heart beats in one minute. Pulse rates vary from person to person. Your pulse is slower when you are at rest and increases when you exercise, since more oxygen-rich blood is needed by the body during exercise.

Knowing how to take your pulse can help you tell if your heart rhythm is regular, evaluate your exercise program, and  in some cases, help your doctor determine if your medications are working properly.

How do I take my pulse?
You can tell how fast your heart is beating by feeling your pulse. You can feel your pulse on your wrist or neck. Place the tips of your index and middle fingers on the inner wrist of your other arm, just below the base of your thumb. Or, place the tips of your index and middle fingers on your lower neck, on either side of your windpipe. Press lightly with your fingers until you feel the blood pulsing beneath your fingers. You may need to move your fingers around slightly up or down until you feel the pulsing.

Your heart rate, or pulse, is the number of beats felt in one minute. You can count the number of beats in 10 seconds and multiply by 6 to determine your heart rate in beats per minute. A normal heart rate, at rest, is 50 to 100 beats per minute.

Your Heart Rate = Pulse in 10 seconds x 6 = ____ beats per minute

What is an arrhythmia?

An arrhythmia (also called dysrhythmia or irregular heart rhythm) is an irregular or abnormal heartbeat.

What are the common types of arrhythmia?

Bradycardia ("slow-heart arrhythmia ")

A slow heart rhythm with a rate below 60 beats per minute is called a bradycardia.

A fast or slow heart rate does not always mean your heart rhythm is abnormal. Fast or slow heart rates are also related to anxiety, activity, medications or other normal causes.

Supraventricular arrhythmias

• Arrhythmias that begin above the ventricles, such as in the upper chambers or atria.
• "Supra" means above; "ventricular" refers to the lower chambers of the heart (ventricles).

These are the different types of supraventricular arrhythmias:

• Premature atrial contractions (PACs)
  early, extra beats that originate in the upper chambers of the heart (atria).
• Paroxysmal supraventricular tachycardia (PSVT)
  a rapid but regular rhythm that comes from the atria. PSVT begins and ends suddenly.
• Accessory pathway tachycardia (such as Wolff-Parkinson-White syndrome)
  a fast heart rhythm due to an extra abnormal electrical pathway or connection between the atria and ventricles. The impulses  travel through the extra pathways, as well as, the usual route. This allows the impulses to travel around the heart very quickly, causing the heart to beat unusually fast.
• AV nodal re-entrant tachycardia (AVNRT)
  a fast heart rate due to having more than one pathway through the atrioventricular (AV) node.
• Atrial tachycardia
  a rapid heart rhythm or arrhythmia that originates in the atria.
• Atrial fibrillation
  a very common irregular rhythm. Many impulses begin and spread through the atria, competing for a chance to travel through the AV node. The resulting rhythm is  disorganized, rapid and irregular. Because the impulses are traveling through the atria in a disorderly fashion, there is a loss of coordinated atrial contractions.
• Atrial flutter
  an atrial arrhythmia due to one or more rapid circuits in the atrium. Atrial flutter is usually more organized and regular than atrial fibrillation.

Supraventricular arrhythmias

Ventricular arrhythmias -- arrhythmias that begin in the lower chambers of the heart.

• Premature ventricular contractions (PVCs)
  are early, extra beats beginning in the lower chambers of the heart (ventricles). PVCs are common. Most of the time they cause no symptoms and require no treatment. In some people, they can be related to stress, too much caffeine or nicotine, or exercise. But sometimes, PVCs can be caused by heart disease or an electrolyte imbalance. If you have a lot of PVCs and/or arrhythmia symptoms associated with them (see the symptoms listed on page 8), you should be evaluated by a cardiologist.
• Ventricular tachycardia (V-tach)
  a rapid rhythm originating from the lower chambers of the heart. This rapid rate prevents the heart from filling adequately with  blood, and less blood is pumped through the body. This can be a more serious arrhythmia, especially in people with heart  disease, and may be associated with more symptoms. A cardiologist should evaluate this arrhythmia condition.
• Ventricular fibrillation (V-fib)
  an erratic, disorganized firing of impulses from the ventricles. The ventricles quiver and cannot generate an effective contraction, making the heart unable to deliver blood to the body. This is a medical emergency that must be treated with  cardiopulmonary resuscitation (CPR) and defibrillation [delivery of an energy shock to the heart muscle to restore a normal  rhythm] as soon as possible. Click here to learn more about sudden cardiac death
• Long QT
  the QT interval is the area on the electrocardiogram (ECG or EKG) that represents the time it takes for the heart muscle to contract and then recover, or for the electrical impulse to fire and then recharge. When the QT interval is longer than normal, it increases the risk for “torsades de pointes,” a life-threatening form of ventricular tachycardia. Click here for more information about Long QT Syndrome

Ventricular arrhythmias

Bradyarrhythmias-- slow heart rhythms that may arise from disease in the heart's conduction system, such as the sinus (or sinoatrial, SA) node, AV node or HIS-Purkinje system.

• Sinus node dysfunction
  slow heart rhythms due to an abnormal SA node.
• Heart block
  a delay or complete block of the electrical impulse as it travels from the sinus node to the ventricles. The level of the block or delay may occur in the AV node or HIS-Purkinje system. The heart may be irregular and slow.

Bradyarrhythmias

What causes an arrhythmia?

Arrhythmias may have many causes, including coronary artery disease, changes in the heart muscle (heart failure or cardiomyopathy), valve disease, electrolyte  imbalances in your blood (such as sodium or potassium), injury from a heart attack or the healing process after heart surgery.

A fast or slow heart rate does not always mean your heart rhythm is abnormal. Fast or slow heart rates are also related to anxiety, activity, medications or other normal causes.

What are symptoms of an arrhythmia?

An arrhythmia may be "silent" and not cause any symptoms. A doctor can detect an irregular heartbeat during physical exam by taking your pulse, listening to your heart or by performing diagnostic tests.

If symptoms occur, they may include:

• Palpitations -- a feeling of skipped heart beats, fluttering, "flip-flops" or feeling that the heart is "running away"
• Pounding in the chest
• Dizziness or feeling light-headed
• Shortness of breath
• Chest discomfort
• Weakness or fatigue (feeling very tired)

How is an arrhythmia diagnosed?

If you have symptoms of an arrhythmia, you should make an appointment with a cardiologist (heart doctor). You may want to choose an electrophysiologist, a cardiologist who has received additional specialized training in the diagnosis and treatment of heart rhythm disorders.

After evaluating your symptoms and performing a physical exam, your cardiologist may perform a variety of diagnostic tests to  help confirm the presence of an irregular heart rhythm and help determine its causes.

Some tests that may be done to confirm the presence of an arrhythmia include:

Electrocardiogram (ECG)
a picture, on graph paper, of the electrical impulses traveling through the heart muscle, recorded by electrodes attached to the skin on the chest, arms and legs.

Ambulatory monitors -- there are several types:

• Holter monitor
  a small portable recorder that is attached to electrodes on the chest. It records the heart rhythm continuously for 24 hours.
• Transtelephonic monitor:
  a small monitor is attached to electrode leads, usually on the finger or wrist. Your heart’s rhythm is transmitted over the phone line, with the aid of this device, to your doctor’s office.
• Transtelephonic monitor with a memory loop
  a small, portable recorder, worn continuously for a prolonged period; records and saves the heart rhythm around the time that an event button is activated. The rhythm is recorded, saved and transmitted over the phone line.

Stress test
a test used to record arrhythmias that are brought on or are worsened by stress or with exercise. This test also may be helpful in determining if there is underlying heart disease or coronary artery disease associated with an arrhythmia.

Echocardiogram
a type of ultrasound used to provide a view of the heart to determine if there is heart muscle or valve disease that may be causing an arrhythmia. This test may be performed at rest or with activity.

Cardiac catheterization
during this test, using a local anesthetic, a catheter (small, hollow, flexible tube) is inserted into a blood vessel and guided to the heart with the aid of an x-ray machine. A contrast dye is injected through the catheter so x-ray movies of the coronary arteries, heart chambers and valves may be taken. This test helps your doctor determine if the cause of an arrhythmia is coronary artery disease. This test also provides information about how well the heart muscle and valves are working.

Electrophysiology study (EPS)
a special heart catheterization that evaluates the heart's electrical system. The catheters inserted into the heart record the electrical activity. The EPS is used to find the cause of the abnormal rhythm and determine the best treatment. During the test, the arrhythmia may be safely reproduced and terminated.

Head upright tilt test (HUT)
a test used to safely reproduce fainting spells in people that may be prone to these episodes (syncope). During the test, the patient is tilted upright on a special table at different angles (usually 30 to 60 degrees). Blood pressure and heart rhythm are recorded. In some people, a fainting spell may be provoked. A medication that may bring on these spells also may be used during the tilt procedure.

How is an arrhythmia treated?

Treatment depends on the type and severity of the arrhythmia. In some cases, no treatment is necessary. Treatment options include: medications, lifestyle changes, invasive therapies, electrical devices or surgery.

Medications
antiarrhythmic drugs are medications used to convert the arrhythmia to a normal sinus rhythm or to prevent an arrhythmia. Other medications may include:

• Heart-rate control drugs
• Anticoagulant or antiplatelet drugs such as warfarin (a "blood thinner") or aspirin, which reduce the risk of blood clots forming or stroke.

It is important to know the names of your medications, why they are prescribed, how often and at what times to take them, what side effects may occur, and what medications you have tried for your arrhythmia in the past. Your doctor or nurse will review with you specific information about your medications and their dosages. If you need any prescriptions, your doctor can write them for you. Check the drug search to find out more about your medications.

Lifestyle changes –
arrhythmias may be related to certain lifestyle factors. Here are some ways to change these factors:

• If you smoke, stop.
• Limit your intake of alcohol.
• Limit or stop using caffeine. Some people are sensitive to caffeine and may notice more symptoms when using caffeinated products (such as tea, coffee, colas and some over-the-counter medications).
• Avoid ingestion of stimulants. Beware of stimulants used in cough and cold medications and herbal or nutritional supplements. Some of these medications contain ingredients that cause irregular heart rhythms. Read the label and ask your doctor or pharmacist what medication would be best for you.

Your family may also want to get involved with your care by learning to recognize your symptoms and beginning emergency medical treatment (cardiopulmonary resuscitation or CPR) if needed.

If you notice that your irregular heart rhythm occurs more often with certain activities, you should avoid them.

Invasive therapies – the following invasive therapies may be used to treat or eliminate irregular heart rhythms. Your doctor will discuss the need and the benefits and risks of these therapies with you.

Cardioversion --
in patients with persistent arrhythmias (such as atrial fibrillation), a normal rhythm may not be achieved with drug therapy alone. After administration of a short-acting anesthesia, an electrical shock is delivered to your chest wall that synchronizes the heart and allows the normal rhythm to restart.

Catheter ablation --
during ablation, energy is delivered through a catheter to tiny areas of the heart muscle. This energy can either:

• "Disconnect" the pathway of the abnormal rhythm
• Block the abnormal pulses and promote normal conduction of impulses
• Disconnect the electrical pathway between the atrial and the ventricles.

Ablation most often is used to treat PSVTs, atrial fibrillation, atrial flutter, AV nodal re-entrant tachycardia, and ventricular tachycardia. Ablation may be combined with other procedures to achieve optimal treatment. See also pulmonary vein isolation ablation.

Electrical devices

Permanent pacemaker
a device that sends small electrical impulses to the heart muscle to maintain a normal heart rate. The pacemaker has a pulse generator (which houses a batter and a tiny computer) and leads (wires) that send impulses from the pulse generator to the heart muscle, as well as sense the heart's electrical activity. Pacemakers are mostly used to prevent the heart from beating too slowly. Newer pacemakers have many sophisticated features that are designed to help with the management of arrhythmias, optimize heart-rate-related functions and improve synchronization.

Implantable cardioverter-defibrillator (ICD)
a sophisticated electronic device used primarily to treat ventricular tachycardia and ventricular fibrillation, two life-threatening abnormal heart rhythms. The ICD constantly monitors the heart rhythm. When it detects a very fast, abnormal heart rhythm, it delivers energy to the heart muscle to cause the heart to beat in a normal rhythm again.

There are several ways an ICD can restore a normal heart rhythm:

• Anti-tachycardia pacing, or ATP:
  when the heart beats too fast, a series of small electrical impulses may be delivered to the heart muscle to restore a normal heart rate and rhythm.
• Cardioversion:
  a low-energy shock may be delivered at the same time as the heartbeat to restore a normal heart rhythm.
• Defibrillation:
  when the heart is beating dangerously fast or irregularly, a higher energy shock may be delivered to the heart muscle to restore a normal rhythm.
  Anti-brachycardia pacing: many ICDs provide back-up pacing to prevent heart rhythms that are too slow.
• Anti-brachycardia pacing:
  many ICDs provide back-up pacing to prevent heart rhythms that are too slow.

An ICD may be combined with a pacemaker to provide additional functions.

Heart surgery --
may be needed to correct arrhythmias not controlled with medications or non-surgical treatment methods. Arrhythmia surgery may also be recommended if you  need surgery to correct other forms of heart disease (such as valve or bypass surgery). The Maze and modified Maze procedures are two surgeries used to  correct atrial fibrillation.

Regular follow-up visits

You will want to visit your doctor for regular follow-up visits, depending on your treatment plan. Your follow-up visits with your doctor can help to:

• Make sure your arrhythmia is controlled
• Properly adjust your medications
• Evaluate the functioning of any implanted devices
• Make sure you are staying healthy and not having other medical problems
• Your doctor will tell you how often you should visit. Call your doctor in between visits if your symptoms become more frequent or severe.

Click here to find a Cleveland Clinic Heart Center Cardiologist who treats abnormal heart rhythms

Learn more about the diagnosis and management of irregular heart rhythms