The AICD medical abbreviation stands for automatic implantable cardioverter defibrillator, an implanted device that monitors every heartbeat and responds with a shock when it senses a life-threatening fast rhythm. Automatic means it works on its own, without anyone pressing a button.
Today most cardiologists simply write ICD, implantable cardioverter defibrillator, and AICD is the older, longer form that still shows up in many problem lists and patient histories. Both describe the same kind of device. Below you will find how it works, where it differs from a pacemaker, and the way notes record it.
At a glance
Stands for
Automatic implantable cardioverter defibrillatorSame as
ICD, the more common modern termTreats
Ventricular tachycardia and ventricular fibrillationSpecialty
Cardiac electrophysiologyDo not confuse with
Where you see it
Problem lists, cardiology notes, surgical and MRI safety checklists
What an AICD does inside the body
There are two pieces. The generator, a sealed metal case a bit larger than a pacemaker, holds the battery and circuitry. Wires run from the case through a large vein and are fixed to the heart wall, where they sense each beat. If the lower chambers start beating dangerously fast, as in ventricular tachycardia or ventricular fibrillation, the device responds.
Its first response is often a burst of quick, painless pacing called antitachycardia pacing, which can break the rhythm. If that fails or the rhythm is chaotic, it delivers a shock to reset the heart. Like a pacemaker, it can also pace a heart that beats too slowly.
AICD medical abbreviation versus ICD, PPM and AED
| Term | Location | Paces slow beats | Shocks fast rhythms |
|---|---|---|---|
| AICD or ICD | Implanted | Yes | Yes |
| PPM | Implanted | Yes | No |
| CRT-D | Implanted | Yes, both ventricles | Yes |
| AED | Outside the body | No | Yes, applied with pads |
One more caution: ICD also stands for International Classification of Diseases, the coding system used for diagnoses. Writing AICD or spelling out defibrillator avoids that mix-up in records where both appear.
Who receives an implanted defibrillator
Doctors describe two broad reasons. Secondary prevention means the person has already survived cardiac arrest or a sustained dangerous rhythm. Primary prevention means they have not, but their risk is high, for example because the heart pumps weakly after a heart attack or from a cardiomyopathy. The pumping strength, written as ejection fraction or EF, is one of the measures that guides the decision, along with symptoms and other tests.
Cardiology history: "Ischemic CM, EF 30%, s/p AICD, one appropriate shock for VT." This means heart muscle weakened by blocked arteries, a pumping strength of about 30 percent, and a defibrillator that has correctly shocked a fast rhythm once.
What the chart notes after implantation
Records follow device checks, often done remotely from home, which report battery life, lead function and any stored rhythm events. Notes record whether shocks were appropriate, meaning given for a real dangerous rhythm, or inappropriate, meaning triggered by something else. Before surgery the team plans how to manage the device, because electrical tools used in the operating room can confuse it. MRI forms ask about it for the same reason.
Questions people often bring to device clinic
- What should I do if I receive a shock?
- Are there limits on driving or certain activities?
- How will remote monitoring work at home?
- When is the generator likely to need replacement?
This page explains the abbreviation and the device in general. Instructions about shocks, activity or device settings should come from the electrophysiology team that manages the device.
More device and procedure shorthand sits in the surgical abbreviations section.
Frequently asked questions
Is an AICD the same as an ICD?
Yes. AICD is the older name and ICD is the term most cardiologists use now. Both mean an implanted defibrillator that can shock a dangerous fast rhythm.
What is the difference between an AICD and a pacemaker?
A pacemaker treats slow heartbeats only. An AICD can also pace, but its main purpose is to detect and stop life-threatening fast rhythms with pacing bursts or a shock.
What does s/p AICD mean?
It means status post AICD placement, so the person already has an implanted defibrillator. Notes may add the reason, such as primary or secondary prevention.
Does an AICD shock hurt?
Many people describe a shock as a sudden strong jolt or kick in the chest that lasts a moment. Pacing bursts used to stop some rhythms are usually not felt or are felt only as a flutter.