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Arrhythmias

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. During an arrhythmia, 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.

Each electrical signal begins in a group of cells called the sinus node or sinoatrial (SA) node. The SA node is located in the heart's upper right chamber, the right atrium (AY-tree-um). 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 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-tre-al fi-bri-LA-shun), 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.

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 light-headedness
  • Sweating
  • Shortness of breath
  • Chest pain

Common arrhythmia treatments include medicines, medical procedures, and surgery. Your doctor may recommend treatment if your arrhythmia causes serious symptoms, such as dizziness, chest pain, or fainting.

Your doctor also may recommend treatment if the arrhythmia increases your risk for problems such as heart failure, stroke, or sudden cardiac arrest.

Medicines
Medicines can slow down a heart that's beating too fast. They also can change 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 treat atrial fibrillation (AF).

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

Currently, no medicine can reliably speed up a slow heart rate. Abnormally slow heart rates are treated with pacemakers.

People who have AF and some other arrhythmias may be treated with blood-thinning medicines. These medicines reduce the risk of blood clots forming. Warfarin (CoumadinĀ®), dabigatran, heparin, and aspirin are examples of blood-thinning medicines.

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

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

Pacemakers have sensors that detect the heart's electrical activity. When the device senses an abnormal heart rhythm, it sends electrical pulses to prompt the heart to beat at a normal rate.

Some arrhythmias are treated with a jolt of electricity 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 used to treat some arrhythmias if medicines don't work. During this procedure, a thin, flexible tube is put into a blood vessel in your arm, groin (upper thigh), or neck. Then, the tube is guided to your heart.

A special machine sends energy through the tube to your heart. The energy finds and destroys small areas of heart tissue where abnormal heart rhythms may start. Catheter ablation usually is done in a hospital as part of an electrophysiology study.

Your doctor may recommend transesophageal echocardiography before catheter ablation to make sure no blood clots are present in the atria (the heart's upper chambers).

Surgery
Doctors treat some arrhythmias with surgery. This may occur if surgery is already being done for another reason, such as repair of a heart valve.

One type of surgery for AF is called maze surgery. During this surgery, a surgeon makes small cuts or burns in the atria. These cuts or burns prevent the spread of disorganized electrical signals.

If coronary heart disease is the cause of your arrhythmia, your doctor may recommend coronary artery bypass grafting. This surgery improves blood flow to the heart muscle.

Other Treatments
Vagal maneuvers are another type of treatment for arrhythmia. 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 manever)
  • 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.