Heart and Vascular Center

Diseases and Treatments

Arrhythmias

The heart has its own electrical system that controls the heart’s rhythm or beating. An arrhythmia is a condition in which the electrical activity of the heart is irregular or is faster or slower than normal. The two main types of arrhythmias are:

Bradycardia (a slow heart rate of less than 60 beats per minute)
Tachycardia (a rapid heart rate of more than 100 beats per minute)

Some arrhythmias originate in the atria (the two upper cambers of the heart), while others originate in the ventricles (the two lower chambers of the heart).

Arrhythmias originating in the atria

Atrial fibrillation (AF), uncoordinated electrical signals emitted in the atria, cause the atria to quiver instead of beating normally. AF increases the risk of stroke and can lead to congestive heart failure.

Atrial flutter is another, more organized form of arrhythmia that occurs when rapidly fired signals cause the muscles in the atria to contract quickly, leading to a fast, steady heartbeat.

Supraventricular tachycardia (SVT), which involves both the ventricles and the atria. It is not life-threatening but may cause symptoms. A series of early beats in the atria speeds up the heart rate.

Wolff-Parkinson-White (WPW) syndrome, an abnormal pathway between the atria and ventricles that causes electrical signals to arrive at the ventricles too soon and to be transmitted back to the atria. Rapid heart rates may develop.

Arrhythmias originating in the ventricles

Ventricular tachycardia (VT), a fast heart rate that starts in the ventricles. VT may or may not be life-threatening. VT may have many causes including cardiomyopathy (heart muscle disease), coronary artery disease, valvular disease, an isolated rhythm problem or a genetic condition (Long Q-T syndrome). Treatment is more complex and may involve treating heart failure in addition to treating the arrhythmia.

Ventricular fibrillation, in which disordered electrical activity causes the ventricles to contract in a rapid, unsynchronized manner. Sudden death follows unless immediate medical help is provided.

Disorders related to arrhythmias

Adams-Stokes disease, a transient condition caused by a heart rhythm disorder, in which the normal electrical signal that passes from the heart’s upper to lower chambers is interrupted.

Bundle branch block, a delay or obstruction in the transmission of the heart’s electrical impulses that impairs the heart’s ability to pump efficiently.

Long Q-T syndrome, a hereditary disorder of the heart’s electrical rhythm that involves repeated fainting and a high risk of cardiac arrest.

Syncope, a temporary loss of consciousness (fainting) usually related to temporary insufficient blood flow to the braining.

Treating Arrhythmias

With few exceptions, all arrhythmias are treatable. Medical College of Wisconsin electrophysiologists specialize in treating complex atrial arrhythmias associated with prior heart surgery and congenital heart disease as well as ventricular arrhythmias caused by coronary blockages and heart attack. Advanced treatment techniques permit the treatment and cure of previously untreatable arrhythmias.

To determine appropriate treatment for an arrhythmia, it must be determined if there is a genetic cause or underlying heart disease. If neither is present, treatment is aimed at alleviating symptoms (e.g., palpitations, low blood pressure, dizziness, fainting, rapid heart beat, chest pain and shortness of breath). If symptoms are mild, no treatment may be needed. People with more severe symptoms may need an implantable defibrillator or radiofrequency ablation.

Medications

Depending on a person’s symptoms and type of arrhythmia, various medications may be prescribed.

Radiofrequency ablation

Radiofrequency ablation can cure many common rhythm problems using radiofrequency energy to eliminate the source of an irregular heart rhythm. In this procedure, an electrophysiologist guides a catheter with an electrode at its tip to the area of heart muscle with the abnormal rhythm. The electrode supplies a burst of radiofrequency energy to eliminate the source of the irregular rhythm. Ablation may not be an option for some patients with significant heart disease.

Froedtert & The Medical College of Wisconsin arrhythmia specialists use a sophisticated technique called computerized electro-anatomical mapping to cure irregular rhythms associated with advanced heart disease. Rhythm problems from heart disease occur largely because of scar tissue; normal tissue conducts electrical impulses, scar tissue doesn’t. The mapping technique allows physicians to precisely locate the scars on a patient’s heart. Using a catheter probe, physicians take electrical readings throughout the heart chamber to generate a three-dimensional scar tissue map of the heart. They then use the ablation catheter to treat the problem.

Pacemaker implant

A pacemaker is a small device that helps the heart beat in a regular rhythm. It uses batteries to send electrical impulses to the heart. There are different types of pacemakers for different needs.

In a minimally invasive surgical procedure (using local anesthesia), a small incision is made in the chest, where the pacemaker and leads are inserted. (A lead is a flexible wire that connects the pacemaker to the heart muscle.) The leads are placed into a vein and moved to the heart, using fluoroscopy to guide the process. The lead is attached to the heart and the other end is attached to a pulse generator placed in the chest (under the skin). After a pacemaker is implanted, it is programmed to the precise needs of the patient.

Cardiac resynchronization therapy

Heart failure is even more severe in people who have bundle branch block, a condition that makes the heart work harder to pump blood. Medical College of Wisconsin electrophysiologists are highly skilled in using cardiac resynchronization therapy (CRT) to treat bundle branch block. CRT uses a specialized pacemaker to re-coordinate the action of the right and left ventricles.

Defibrillator implant

If ablation is not an option for a patient, an implantable cardioverter defibrillator (ICD) may be implanted in the body to prevent cardiac arrest. An ICD continuously monitors the heart’s rhythm and recognizes rapid arrhythmias such as ventricular tachycardia (VT) and ventricular fibrillation (VF). The defibrillator corrects the rapid rhythm by delivering a high-voltage electrical shock, when needed, to restore a normal heartbeat. Less often, a person might have a heart rhythm that is too slow. In this case, a pacemaker (built into all ICDs) will send a low electrical pulse to the heart to “remind” it to beat.

An ICD is implanted during a minimally invasive surgical procedure in which the pulse generator is surgically implanted under the skin in the upper chest. A wire from the ICD is threaded through the blood vessels to the heart. The procedure takes less than two hours and, following an overnight hospital stay, the patient may return home.

Maze procedure

The Maze procedure is performed by cardiac surgeons to treat atrial fibrillation in certain patients. Atrial fibrillation, the most common type of arrhythmia, is commonly caused by aging, when areas of scarring or fibrosis develop in atria (the two upper chambers of the heart). Many other conditions can also cause atrial fibrillation, particularly diseases of the heart valves.

The Maze procedure is performed on the atria during open-heart surgery (requiring heart-lung bypass). Certain parts of the atria are frozen or treated by open radiofrequency, either of which creates electrical conduction blocks to form a Maze, forcing impulses to travel in an organized fashion. The atrium can then hold blood and contract to push the blood into the ventricle, but the electrical impulse cannot cross the incisions. The normal rhythm of the heart is restored because the atrium can no longer fibrillate.

Froedtert & The Medical College of Wisconsin have a high success rate with the Maze procedure.

Last Review Date: Aug. 26, 2009

Online Editor(s): Richard Petre