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Pacemaker Implant: How Is Cardiac Resynchronization Therapy Done?

What is cardiac resynchronization therapy?

Cardiac resynchronization therapy involves inserting electrodes into the heart attached to an electrical pacemaker device, which will administer electrical current when the heartbeat falls out of rhythm.Cardiac resynchronization therapy involves inserting electrodes into the heart attached to an electrical pacemaker device, which will administer electrical current when the heartbeat falls out of rhythm.

Cardiac resynchronization therapy (CRT) is a treatment to help the heart beat with healthy rhythm. CRT is a minor surgical procedure to implant an electronic device under the skin. The device helps coordinate the timing of the contraction of the heart’s lower chambers (ventricles), and improves the heart’s pumping function.

How does CRT work?

The CRT device has insulated leads that are attached to the right and left ventricle, right atrium and the coronary sinus vein (the blood vessel that returns the oxygen-depleted blood from the organs to the right atrium). 

The CRT device delivers tiny electrical impulses to the ventricles to synchronize their contraction. The CRT device has an inbuilt battery that lasts for about 5 to 7 years, after which it will require replacement.

Is CRT the same as a pacemaker?

Yes. CRT refers to implantation of a pacemaker, and there are two types.

  • CRT-P (cardiac resynchronization therapy-pacemaker): This device, also known as a biventricular pacemaker, delivers regular electric impulses making the ventricles contract with normal rhythm.
  • CRT-D (cardiac resynchronization therapy-defibrillator): Besides functioning as a regular pacemaker, this device senses when the heart beats dangerously fast and delivers a shock to stop the abnormal rhythm. This device is used for people with heart failure who have a high risk of sudden cardiac death.

Why is cardiac resynchronization therapy done?

Cardiac resynchronization therapy is performed as a treatment for heart failure due to irregular heartbeat (arrhythmia). Arrhythmia may be caused by factors such as

By resynchronizing the heart’s rhythm the CRT improves the heart’s efficiency and the blood flow.

Does CRT cure heart failure?

CRT is useful in improving left ventricular function and relieving symptoms of heart failure such as palpitations and shortness of breath. CRT is not useful for all heart failure patients.

CRT does not cure heart failure, it can only slow down its progress. Heart failure is a chronic progressive disease that requires management with medications and lifestyle changes.

Heart failure may be caused by many factors such as

How is cardiac resynchronization therapy done?

A cardiac surgeon performs CRT with mild sedation and local anesthesia for most people. Some may require general anesthesia, especially if any other cardiac surgery is performed along with pacemaker placement. The CRT procedure alone may take up to five hours and require a day of hospitalization.


Before a CRT, the patient

  • Undergoes physical examination and blood tests.
  • Undergoes electro and echocardiography.
  • Must avoid eating or drinking 8 hours prior to the procedure.
  • Check with the doctor before taking any regular medications.
  • Inform the doctor of any allergies or implants.


During the procedure the surgeon

  • Attaches an IV line and administers medication for sedation and pain.
  • Monitors the patient’s blood pressure, heart rate and oxygen levels.
  • Administers local anesthesia in the area where the device will be implanted, typically under the left collarbone.
  • Makes an incision and creates a pocket under the skin to place the battery pack of the CRT device.
  • Advances the CRT device’s 4 insulated leads through the coronary sinus vein and positions one each in the right atrium, right and left ventricles, and the sinus vein.
  • Tests the device to make sure it works well.
  • Places the pacemaker in the pocket created, covers it with the skin flap, and closes the incision with sutures.


  • The patient is monitored for a few hours in the recovery room.
  • Most people are discharged the same day or the next.
  • Most patients will be able to return to normal activities in 6 weeks but may have restrictions for certain activities.
  • Depending on underlying conditions, some patients may have to modify diet and lifestyle.
  • The patients must follow up with regular checkups to ensure proper functioning of the device.

What are the risks and complications of cardiac resynchronization therapy?

CRT is a minor surgical procedure that can save lives. Complications and risks that may arise include:

During the procedure

  • Bleeding and blood clots
  • Injury to the vein, muscle or nerve
  • Damage to the heart or lung
  • Arrhythmia or heart attack
  • Inability to place the leads in correct position

After the procedure

  • Infection
  • Pain and irritation at the implant site
  • Movement of the device or the leads out of place
  • Malfunction or failure of the device

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