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Heart Rhythm Treatments

Heart rhythm and electrical system treatments available at Memorial Hermann include:


To correct atrial fibrillation or reset the heart to its regular rhythm (sinus rhythm), physicians may perform a procedure called cardioversion, using either drugs or electricity.

Cardioversion is not always effective. It may successfully restore regular heart rhythm in more than 95 percent of patients, but more than half of patients eventually go back into arrhythmia. In many instances, anti-arrhythmic medications are needed indefinitely.

What is chemical cardioversion?

Medicines (anti-arrhythmics) are used to stop the heart's quivering and restore normal sinus rhythm. The medications help maintain sinus rhythm for at least 1 year in 50 percent to 65 percent of people. However, they can cause side effects such as nausea and fatigue, as well as some long-term risks. In rare cases, the medications may adversely affect heart rhythm.

What is electrical cardioversion?

While under light anesthesia, a patient receives an electrical shock through paddles or patches on the chest. The shock stops the heart's electrical activity for a split second. When the heart's electrical activity resumes, the rhythm may be normal.

Heart Ablation

For arrhythmias caused by abnormal heart tissue, catheter radiofrequency ablation (heat) can be used to destroy the abnormal heart tissue.

Catheters (thin, flexible tubes) are threaded through the patient's blood vessels to reach the abnormal heart tissue. The cardiologist then uses a small cutter or radiofrequency energy to remove the abnormal tissue. The procedure does not require open chest surgery.

Implantable Cardioverter Defibrillator

For arrhythmias in which the heart beats too rapidly (tachycardia) or quivers (fibrillates) instead of contracting strongly, an internal cardioverter defibrillator (ICD) can be surgically implanted.

The ICD sends electronic signals to the heart whenever the heart rate reaches a specified limit or goes very high. These signals shock the heart into beating more slowly and pumping more effectively. An ICD is generally not used to treat atrial fibrillation.


A pacemaker is a device that helps regulate the heartbeat. The device, smaller than a matchbox, is placed under the skin near the collarbone. A wire extends from the pacemaker to the heart.

If a pacemaker detects an abnormally slow heart rate (bradycardia) or no heartbeat, it emits electrical impulses that stimulate the heart to speed up or resume beating.

A pacemaker is often implanted if medications to prevent arrhythmia or control the heart rate result in an excessively slow rate, and following AV node ablation.


Left Atrial Appendage Closure Device (LAAC)

In patients with atrial fibrillation, the flow of blood in the right and left atria of the heart is often slower than normal, and this reduction in speed can also cause blood clots. These clots are more likely to arise in the left atrial appendage, a pocket-like structure that is part of the left atrium. If a blood clot dislodges and moves to another area of the body, it can block the supply of blood to that body part. For example, when a blood clot in the left atrial appendage breaks loose and travels to the brain, it can halt normal blood flow and cause permanent damage in the form of a stroke. People who suffer a stroke may have difficulty walking, problems speaking, or changes in sensation. Strokes can even cause death.

The WATCHMANTM Left Atrial Appendage Closure device, commonly referred to as “WATCHMAN,” is an implant that is placed at the opening of the left atrium, the upper left chamber of the heart. Making the WATCHMAN technology available to our patients helps us improve outcomes and speed recovery. Clinical studies have shown the WATCHMAN device holds two major benefits for patients with atrial fibrillation as well as other conditions that put them at increased risk of stroke. First, WATCHMAN can reduce the risk of stroke from a blood clot that forms in the left atrial appendage. Second, this device may also enable patients with atrial fibrillation to discontinue long-term use of warfarin, an anti-coagulant (blood thinner) that could cause bleeding and must be monitored regularly.

Contact Us

For more information about heart rhythm treatment at Memorial Hermann Heart & Vascular Institute use our contact form here. Schedule an appointment with a Memorial Hermann Cardiologist online or by calling (713) 222-2273.