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Site FeedbackCardiac Resynchronization Therapy (CRT)
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Description | Treatment Options | John Muir Health Capabilities
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Definition
More than 22 million people worldwide suffer from heart failure, a debilitating disease. For a long time, lifestyle changes, medication and, sometimes, heart surgery were the only treatment options. Patients with severe symptoms had little relief from such approaches. More than 40 percent of patients with CHF have an arrhythmia that decreases the heart's ability to beat properly. Cardiac resynchronization therapy (CRT) is an new therapy that can relieve CHF symptoms by improving the coordination of the heart's contractions. CRT uses technology found in pacemakers and implantable cardioverter devices. CRT devices additionally protect an individual from slow and fast heart rhythms.
Description
The heart is comprised of four chambers: two uppers chambers (atria), and two lower chambers (ventricles). An electrical system regulates and synchronizes the pumping action of these chambers. The normal heartbeat originates in a section of the right atrium known as the sinoatrial, or SA node. In the normal heart, the electrical signal spreads through both atria causing them to contract and squeeze blood into the ventricles. The electrical signal then passes through an electrical bridge known as the atrioventricular or AV node. After a very short delay, the signal continues to the ventricles using special conduction fibers known as bundle branches.
The bundle branches carry the electrical signal and stimulate both ventricles at the same time. The ventricles then contract or squeeze together to pump blood throughout the body and lungs. Coordinated contraction is necessary for the heart to pump effectively.
When a delay happens and the electrical signal transmission (the electrical signal to one of the ventricles) is delayed, the ventricles do not contract evenly. The result is an asynchronous or uncoordinated contraction of the ventricles. This decreases the efficiency of the heart.
Resynchronization (CRT) corrects the timing and reestablishes the normal coordinated pumping action of the ventricles. Using a very special device, the heart's ventricles are stimulated equally. Studies have shown that these powerful, "built-in" devices improve the quality of life for those with heart failure. CRT uses a pacemaker to provide coordinated impulses to the ventricles.
Pacemakers have been used for years to correct dangerously slow heart rhythms. The pacemaker continuously monitors the heartbeat and, when necessary, delivers tiny, electrical signals to stimulate the heartbeat. Using very thin wires, a tiny electrical signal travels from a battery-operated generator to the heart muscle. The generator is placed under the skin in the upper chest where it monitors the heart rate continuously. If the heart rate slows, the pacemaker goes to work stimulating the heart to increase the rate.
The CRT is similar to the traditional pacemaker except that the CRT device has the ability to simultaneously stimulate both ventricles. This restores a coordinated, or "synchronous," squeezing pattern. This is sometimes referred to as "bi-ventricular pacing" because both ventricles are electrically stimulated (paced) at the same time. The electrical delay is reduced and a more coordinated and effective heart beat is established. With improved pumping, blood is circulated throughout the body. Improved circulation decreases fatigue and difficulty breathing.
Treatment Options
When is CRT the right choice?
The ideal candidate for a CRT device is someone with:
- Moderate to severe heart failure symptoms, despite lifestyle changes and medication
- A weakened and enlarged heart muscle
- A significant electrical delay in the lower pumping chambers
Some CRT candidates have a high risk of sudden cardiac death from rapid irregular heart rhythms. For these patients, a special CRT device can stop potentially life-threatening rapid heartbeats. This is done by delivering a lifesaving jolt of electricity to restore the heart's normal rhythm and prevent sudden cardiac death. This device incorporates a standard implantable cardioverter defibrillator (ICD) with a CRT pacemaker creating a "CRTD" device. (The "D" refers to defibrillation.)
John Muir Health Capabilities
John Muir Health is very proud of its Cardiac Rhythm Center. John Muir Health has eight leading cardiac rhythm specialists in the Bay Area on staff at John Muir Medical Center, Walnut Creek Campus and John Muir Medical Center, Concord Campus. These rhythm specialists are cardiologists who completed special training in the care of individuals with heart rhythm problems. Special equipment and well-trained staff at John Muir Health are available to care for those with the complex and life-threatening problems.
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