Cardiac Resynchronization Therapy

Safety and use information

Safety and Use

Find important safety and use information for our implantable devices and systems.

Education Opportunities

Patient Stories

Read about the experiences of heart failure patients and how treatment helped them.

Common questions
to Ask

Bring this list of questions about treating heart failure to your next appointment with your doctor—and be sure to take notes during your conversation.

Types of Cardiac Resynchronization Therapy Devices

If you have been diagnosed with heart failure, your doctor may recommend that you receive a cardiac resynchronization therapy (CRT) device, depending on your symptoms, type of heart failure and the severity of your condition. A CRT is an implantable device that stimulates the heart’s lower chambers, and often one upper chamber, so they are synchronized and more efficient in pumping blood to the body.

Two types of CRTs are available for managing long-term heart failure, depending on your type of heart failure:

  • Cardiac resynchronization therapy pacemakers (CRT-Ps)
  • Cardiac resynchronization therapy implantable cardioverter defibrillators (CRT-Ds)

Cardiac resynchronization therapy pacemakers (CRT-Ps)

A CRT-P is a pacemaker specialized for managing heart failure. Essentially a minicomputer, a pacemaker functions to replace the work of your heart’s natural pacemaker, the sinus node. With a pacemaker’s help, your heart can maintain a normal, healthy rhythm so it can circulate the amount of blood needed to meet your body’s need. Similar to a traditional pacemaker, the CRT-P helps keep your heart from beating too slowly or out of rhythm.

A traditional pacemaker has one or two leads (wires) that are placed into the right side of your heart. One lead is placed into the lower right chamber, called the right ventricle. A second lead may be placed into the right upper chamber, called the right atrium. A CRT-P has an additional lead placed on the left side of the heart to make the left ventricle beat at the same time as the right.


You might need a CRT-P if:

  • You have symptoms of heart failure despite medication and lifestyle changes
  • Your heart beats too slowly
  • The ventricles of your heart do not contract simultaneously and your heart is in need of resynchronization
  • You have heart failure

Cardiac resynchronization therapy implantable cardioverter defibrillators (CRT-Ds)

A CRT-D is a type of specialized implantable cardioverter defibrillator (ICD) that manages heart failure by sending an electric shock to the heart. Like a pacemaker, an ICD is a battery-operated cardiac device that your doctor implants surgically. When it detects an abnormally irregular or fast heart rate, the device delivers an electrical shock in order to restore and establish a normal rate. Your doctor will program the device so that it will not deliver an electric shock when you exercise or raise your heart rate by becoming active.

Traditional ICDs send electrical shocks to the heart through thin insulated wires, also called leads, which attach to the heart muscle. CRT-D devices also provide electrical impulses, similar to a pacemaker, through an additional lead that attaches to the left ventricle. The CRT-D’s extra lead allows it to synchronize the heart’s rhythm and increase its pumping efficiency.

You may need a CRT-D if:

  • You previously have had or are at risk for having ventricular tachycardia (VT) or ventricular fibrillation (VF), causing your heart to beat too fast 
  • You have damage to the pumping action of your heart caused by a heart attack
  • You have heart failure

Learn more about what receiving treatment for heart failure can involve.