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Cardiac Resynchronization Therapy: Basic Knowledge

This page will provide you with general information about cardiac resynchronization therapy pacemakers (CRT-P) and defibrillators (CRT-D). It will explain how they can help heart failure patients, how they are implanted and things to watch out for before and after surgery.  

Physician holding a BIOTRONIK device in her hands

What Is A CRT?

In patients with a weakened heart muscle, the heart tries to make up for lost pumping power, which can lead to an inefficient, irregular heartbeat in which the heart’s lower chambers no longer work in tandem. As a result, the body can lack enough oxygen-rich blood and patients may experience dizziness, fatigue or even fainting. 

Therapy for heart failure aims to improve the heart’s ability to pump oxygen-rich blood through the body. It often consists of a combination of different interventions, such as lifestyle changes, medication, or a cardiac implant. Cardiac resynchronization therapy devices support the weakened heart by monitoring the heart’s rhythm, detecting irregularities, and correcting them with electrical impulses when necessary.

Cardiac resynchronization therapy devices include:

Cardiac resynchronization therapy with a pacemaker (CRT-P). The device is used for the resynchronization of the two ventricles.

They are small, battery-powered devices that are implanted near the collarbone. They consist of a pulse generator as well as three special wires, called leads, that connect the heart with the pulse generator. They relay information about the heart's rhythm back to the pulse generator and carry small electrical pulses from the device to the heart.

Cardiac resynchronization therapy with a pacemaker and an ICD (CRT-D). This device may be recommended for people with heart failure who also have a risk of sudden cardiac death. It can detect dangerous heart rhythms and deliver a stronger shock of energy than a pacemaker can deliver. This shock can reset the heartbeat.

Before the Implantation

In case your physician has recommended implantable cardiac resynchronization therapy to you, you will receive detailed instructions about how to prepare for the surgery. Your cardiologist may advise the following among other things: 

  • To stop taking blood-thinning medication several days before surgery. 

  • To stop eating for about 12 hours prior to the implantation. 

  • If you take other medication regularly, ask your physician if you should continue taking the medication before your procedure. 

In addition to the information your healthcare professional will provide, we have put together frequently asked questions and a checklist that you might want to look at and go over with your physician. 

Implantation Procedure

Implanting a CRT-P or CRT-D is a relatively simple surgery that lasts between two and four hours. It is not performed on an open heart. It is carried out under local anesthesia, and sometimes, short-term sedation. You will also be given antibiotics to reduce the risk of inflammation or of an infection. 

After preparing the incision site, the physician will make a cut in your upper chest, well below your shoulder. The surgeon will insert three special wires, called leads, into a major vein near your collarbone. Using X-ray for visibility, the surgeon will guide the leads through your veins and place them in the heart’s upper and lower chambers. Then, the physician will implant the CRT-P or CRT-D in a pocket created at the incision beneath the skin. The surgeon will connect the leads to the device and program it to your specific medical needs. After a test to ensure that the implant is working correctly, the surgeon will close the incision with a few stitches. 

After the Implantation

Usually, you will stay in the hospital for one or two days after the implantation. Listen carefully to and follow your physician’s instructions. At home, monitor how the incision is healing. In some patients, and this is perfectly normal, the device forms a small but visible bulge underneath the skin. Your arm’s range of motion will probably be limited until the wound is completely healed.

From now on, you will have regular follow-up appointments where your physician checks the information your device has stored. He or she will also make necessary therapy adjustments in case they are needed. Please always carry your patient identity card with you so that it is available in case of an emergency.

Of course, you will need some time to get used to living with a device and may have many questions regarding working, traveling or practicing sports. Please also familiarize yourself with how electromagnetic interference can influence your devices’s functionality and what to bear in mind when undergoing medical examinations such as an MRI.

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