Pacemakers, ICDs and CRT Explained
Cardiac devices such as pacemakers, implantable defibrillators (ICD) and resynchronisation devices (CRT) support or protect the heart's rhythm. This page explains how they work, when they may be considered according to current guidelines, and what living with a device involves.
Written by Dr. Jan Niclas Strickling, DHA-licensed: Consultant Cardiology · Consultant Internal Medicine · Specialist Interventional Cardiology. General information only; it does not replace an individual assessment.
Types of Cardiac Devices
The appropriate device, if any, depends on the underlying rhythm problem, symptoms and heart function. Device selection follows current guidelines such as those of the European Society of Cardiology.
- Single- and dual-chamber pacemakers
- Implantable cardioverter-defibrillators (ICD)
- Cardiac resynchronisation therapy (CRT)
- Conduction system pacing (e.g. LBBAP)
- Leadless pacemakers
- Subcutaneous ICD (S-ICD)
Conduction System Pacing
Conduction system pacing, such as left bundle branch area pacing (LBBAP), aims to stimulate the heart's own electrical pathways more directly than conventional pacing. Observational studies and early randomised data are encouraging, but long-term outcome data are still being collected, so it is currently used in selected patients.
Living With a Device
After implantation, regular device checks confirm that the device works correctly and allow settings to be adjusted over time. Many devices support remote monitoring. Advice on driving, exercise and electromagnetic interference depends on the device and local regulations and should come from the treating team.
Frequently Asked Questions
- A pacemaker may be considered when the heart beats too slowly or pauses because of a problem with its electrical system, causing symptoms such as dizziness, fainting or marked fatigue, or when certain conduction abnormalities carry a risk. Reversible causes, such as some medications, are usually excluded first. The decision is individual.
- A pacemaker mainly treats slow heart rhythms by delivering small electrical impulses. An implantable cardioverter-defibrillator (ICD) also monitors for dangerous fast rhythms and can deliver a shock to restore a normal rhythm. Some devices combine both functions.
- Cardiac resynchronisation therapy (CRT) uses an additional lead to coordinate contraction of the heart's chambers. It may be considered for selected people with heart failure, reduced ejection fraction and specific ECG findings. Not everyone responds to CRT.
- Possible complications include bleeding or bruising, infection of the device pocket or leads, lead displacement requiring repositioning, and rarely a collapsed lung or injury to the heart. Devices also need lifelong follow-up and eventual battery replacement. Individual risks should be discussed with the implanting team.
General information, not personal advice
These pages explain conditions and procedures in general terms. Whether a test, medicine or procedure is appropriate, and its alternatives and risks, can only be decided after an individual assessment by your own treating doctor. If you have chest pain, severe breathlessness or collapse, call emergency services immediately.
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