Cardiac resynchronization therapy


Cardiac resynchronization therapy (CRT), also known as biventricular pacing, involves the placement of a permanent biventricular pacemaker. This ensures that the heart’s lower chambers, the ventricles, contract simultaneously instead of asynchronously.

A biventricular pacemaker, also known as a cardiac resynchronization device, is used to provide electrical signals to the right and left ventricles of the heart. The signals cause the ventricles to contract more precisely, which enhances the heart’s ability to pump blood.

A CRT, or biventricular pacemaker has three wires or leads as opposed to other pacemakers’ one or two. These leads help to detect irregular heartbeats and send an electrical signal to fix them so that the heart’s chambers can beat in unison. In some cases, the device also includes an implantable cardioverter-defibrillator (ICD).

Reasons for undergoing the procedure

In between 20% and 30% of patients with heart failure, the lower heart chambers fail to contract in unison. The heart muscle becomes weakened and may struggle to pump an adequate amount of blood to meet the body’s demands.

Cardiac resynchronization therapy may lessen the signs and symptoms of heart failure as well as the danger of fatal consequences. Following the use of medicine and lifestyle modifications, CRT is usually the next course of treatment. With cardiac resynchronization therapy, both heart ventricles are assisted to contract at the same time.

CRT is also widely used for patients with heart failure and left bundle branch block, as well as for those whose low heart rates make cardiac pacing likely to be necessary.


The type of implant and an individual’s overall health play crucial roles in determining the potential risks associated with cardiac resynchronization therapy. Some possible complications that may arise include:

  • Pneumothorax, or lung collapse
  • Infection
  • Blood loss
  • Blood clots
  • Device failure
  • Breaking or shifting wires that could potentially cause damage
  • Moving of device components, which may call for a different process
  • Cardiac tamponade, which is the compression of the heart as a result of fluid accumulation in the sac that surrounds it
  • Allergic reaction to a procedure-related item
  • Another heart disease or a heart attack


This procedure involves a minor surgical approach. During the surgery, electrodes are carefully inserted into a major vein under or close to the collarbone and then guided to the heart with the assistance of X-ray images. One end of each wire is precisely connected to the appropriate location within the heart, while the opposite end is linked to a pulse generator, typically positioned beneath the skin in proximity to the collarbone.

Devices used in cardiac resynchronization therapy include:

  • Cardiac resynchronization therapy with a pacemaker (CRT-P), has three leads that connect to the right upper chamber and both lower heart chambers.
  • Cardiac resynchronization therapy with a pacemaker and an ICD (CRT-D) can identify harmful heart rhythms and administer a more powerful shock of energy compared to a pacemaker. The shock can reset the heart’s rhythm. For individuals with heart failure who face a risk of sudden cardiac death, this device may be advised.

Before being discharged, the implanted device will be checked to ensure that it is properly programmed.

Before the procedure

Prior to the procedure, anesthesia will be administered to ensure that patient will not experience pain. The type of anesthesia used may vary, and it could induce sleep to keep one unaware of the procedure. Imaging tests like a heart MRI or transthoracic echocardiogram may be ordered a few days before the procedure.

During the procedure

The procedure usually begins by inserting three wires through the veins in your upper body or thigh which will be threaded to the heart. Then, an incision is done either below the collarbone or in the abdomen to accommodate the CRT device.
After connecting the wires to the CRT device and ensuring its functionality, they will implant the device under the skin and finally close the incision with stitches.

After the procedure

Keeping the left arm immobile for approximately 12 hours post-CRT is recommended to ensure the leads remain securely in place. The patient will be given a card containing device information to carry with them.

The healthcare provider may conduct X-rays to evaluate the leads and perform electrocardiograms (EKG) to monitor the patient’s heart rhythm. They may also assess the device’s ability to transmit information.


Cardiac resynchronization therapy typically has a duration of a few hours, with most patients requiring an overnight hospital stay. The majority of individuals can resume their regular activities within a few days, although certain limitations may apply, such as restrictions on driving and heavy lifting for a specified period.

Follow-up appointments are typically scheduled one month after the CRT procedure and subsequently, once or twice a year. If an individual experiences a fever several weeks or even months following CRT, it is advisable to contact their healthcare provider, as this could be an indication of an infection at the site of the biventricular pacemaker.