Cardiac resynchronization therapy



Cardiac resynchronization therapy is a treatment for some people who have heart failure. It helps the heart chambers squeeze in a better and more organized way. CRT helps the heart better pump blood to the body.

Cardiac resynchronization therapy (CRT) uses a device called a biventricular pacemaker, also called a cardiac resynchronization device. The device sends electrical signals to the lower chambers of the heart, called the ventricles. The signals tell the lower chambers to squeeze at the same time.

Some CRT devices also have a device called an implantable cardioverter-defibrillator (ICD). An ICD corrects a dangerous heart rhythm.

Why it's done

Cardiac resynchronization therapy (CRT) is a treatment for some people with moderate to severe heart failure. Other treatments, including medicines, are usually tried before CRT is recommended.

Your healthcare team may suggest CRT if:

  • You have heart failure and an irregular heart signaling condition such as left bundle branch block.
  • You need a pacemaker or defibrillator due to a heart condition.

Cardiac resynchronization therapy may help reduce symptoms of heart failure such as shortness of breath. When combined with other treatments, CRT may:

  • Improve quality of life.
  • Reduce the risk of a hospital stay due to heart failure.
  • Help prevent heart failure complications.

CRT is not for people with only mild heart failure symptoms.


Risks of cardiac resynchronization therapy may depend on the type of device used and your overall health.

Risks related to the device and surgery to place the device may include:

  • Infection.
  • Bleeding.
  • Collapsed lung.
  • A hole in a heart chamber, causing fluid and blood to collect in the sac surrounding the heart.
  • Failure of the device.
  • Movement of device parts, which could require another procedure to correct.

What you can expect

Cardiac resynchronization therapy (CRT) requires a minor surgery to place a device in the chest. CRT devices include:

  • Cardiac resynchronization therapy with a pacemaker (CRT-P). This device is for people who have certain stages of heart failure and irregular heart signaling. It sends signals that make the lower heart chambers beat at the same time. It helps the heart fill with blood properly.
  • Cardiac resynchronization therapy with a defibrillator (CRT-D). This combination device uses a pacemaker and an implantable cardioverter-defibrillator (ICD). It may be recommended for people with heart failure who also have a risk of sudden cardiac death. It can find dangerous heart rhythms and correct them. It can pace the heartbeat or shock the heart out of a dangerous heart rhythm.


A member of your healthcare team puts an IV into your forearm or hand. Medicine called a sedative goes through the IV. It helps you relax.

Usually, medicine is used to numb the skin where the CRT device will be placed. This is called local anesthesia. During the surgery to place the device, you may be fully awake or lightly sedated.


The surgery to place the CRT device usually takes a few hours.

How the surgery is done may depend on the type of CRT device you're getting.

For example, to place a pacemaker, a heart doctor inserts one or more wires, called leads, into a major vein under or near the collarbone. The doctor moves the wires to the heart using X-ray images as a guide. One end of each wire connects to the proper area in the heart. The other end attaches to the part of the CRT device that delivers electrical pulses.


You usually stay in the hospital overnight after getting a cardiac resynchronization therapy (CRT) device. Make plans to have someone drive you home from the hospital.

Most people can go back to their usual activities after a few days. Your care team gives you specific instructions to follow. You might be told to limit upper body and arm activities. Your healthcare team also may tell you not to do strenuous exercise or lift heavy items for about a month.