Cardiac resynchronisation therapy

Heart failure is a debilitating and progressive condition where the heart is incapable of pumping enough blood meet the body’s needs.  However, a significant number of heart failure patients do not have a weak heart but suffer instead because the heart’s main pumping chambers are no longer contracting in sync. Despite what might otherwise be a healthy heart, these patients experience the distressing symptoms of heart failure because of an arrhythmia that has caused a delay in the electrical conduction through the heart. This delay can be identified on an electrocardiogram (ECG) and is called a bundle branch block.

CRT stands for cardiac resynchronisation therapy. A CRT device can ‘retune’ the heart’s timing to reduce or eliminate symptoms while also helping to prevent further weakening of the heart.

CRT device

A CRT device is a special pacemaker that specifically aims to improve the coordination of the heart’s contractions. It consists of a pulse generator placed under the skin below the collarbone that is connected to three leads that are threaded along veins to the heart. Two of the leads are the same as those in a normal pacemaker. The third lead enables both of the ventricles of the heart to be stimulated at the same time. This can improve heart function, reducing the symptoms of heart failure, by retuning the timing of the heart’s contractions.

If you have an abnormality in the electrical pathway of your heart which upsets its regular beating, a pacemaker can be inserted to produce electrical impulses to make your heart chambers pump more regularly. CRT-Pacemakers work like traditional pacemakers but are more advanced. In heart failure the left side of the heart may not pump at the same time as the right, meaning the two sides of the heart lose their coordination. CRT-pacemakers have an additional lead which helps restore the hearts coordination and make the heart beat more efficiently. It is important to note that any device is NOT a replacement for your heart failure medication.


There are two types of CRT device: CRT pacemakers (CRT-P) and CRT defibrillators (CRT-D).

A CRT pacemaker is designed only to resynchronise the heart’s contractions to reduce the symptoms of heart failure. However, some CRT patients are at risk of dangerous fast arrhythmias that can put your life at risk if they are not treated rapidly. An implantable defibrillator has the ability to pace or shock the heart back into a normal rhythm. Some CRT devices are combined with a defibrillator in the same pulse generator (CRT-D) to give both resynchronisation support to the heart function and protection from dangerous fast arrhythmias. However not all patients having a CRT device need both. Your doctor will have spoken with you before the procedure to explain which of the two options are most suitable for you.


Your cardiologist will have explained to you why you need to have the CRT device and the benefits and risks of having one implanted.

The procedure is usually performed under a local anaesthetic and you may be given sedation, which will make you relaxed. The doctor will inject some local anaesthetic under the skin just below your collarbone (usually the left side). This will numb the area and allow the doctor to pass the leads through the vein that comes from your arm and runs into your heart. The leads are then connected to the pulse generator, which is about the size of a matchbox. This will be placed under the skin in your chest. The doctor may test the device during the procedure to ensure it is working correctly. You may feel your heart beat go faster as the doctor tests each lead in turn. The incision will then be closed with stitches.

After implant

After the procedure you will be taken back to the ward. You will be asked to lie in bed for a couple of hours before you can get up, eat and drink. As the wound can feel quite bruised and sore, especially for the first day or two, your nurse will give you regular painkillers. It is very important that you tell your nurse immediately if you have any pain. You will also be given antibiotics to take before and after the procedure to minimise the risk of infection. The wound should be kept clean and dry until it has fully healed, although it is fine to have a bath or shower after the first three or four days.

Ask your nurse for a protective dressing so that you can bathe without getting the wound wet. Report any problems to your nurse. You should not lift the arm on the same side as the CRT device above shoulder level for the first two weeks. This is because there is a small chance that the leads could move out of position. However, it is important to do gentle arm and shoulder exercises to keep the arm mobile. You will probably be allowed to go home the next day provided your device is checked, there are no complications and your clinician assesses it is safe. Your device will be checked before you go home by a cardiac physiologist. This check will involve the use of a special programmer that can look at the device settings and make sure it is working properly. It will also be set to the best programme for your condition. The check will take about 15 minutes and can either be done on the ward or in the pacemaker clinic. Most patients will also have a chest x-ray to check lead positions and make sure all is well following the implant procedure. Please ask the physiologist if you have any questions or worries about the device.

You will be given an ICD identity card, emergency information and instructions at this check. You will also be given a helpline number should you have any queries later on.

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