FAQ

Not necessarily. A full shock is usually noticeable and can feel like a sudden strong thump to the chest. Most people describe it as startling rather than painful, though experiences vary.

ATP (anti-tachycardia pacing), however, often works without the person being aware of it at all. It delivers a rapid burst of pacing to interrupt an arrhythmia before it escalates to the point where a shock is needed.

Some episodes of arrhythmia are also brief enough to resolve before the device needs to intervene at all, but the device will still record them. It is entirely possible to have a significant episode detected by your ICD without knowing anything about it until the data is downloaded at your clinic.

If you receive a brief electric shock from UK mains (240v) and have no visible injuries, the risk of damage to your ICD or lead is theoretically present but extremely unlikely and would be classed as very low risk.

This is because the current tends not to pass through the ICD or lead but passes through the body to the ground using the shortest and quickest route — for example, hand, up the arm, down the torso, and out through the leg. The majority of devices also have circuitry built in to protect them against electrical surges.

If you are feeling unwell after the shock, go to hospital. Otherwise, contact your local device clinic and request a device check, which can often be performed as a remote transmission. This will pick up any rare issues and provide reassurance.

They may feel something if you are touching them when you receive a shock, just as they might if you were touching out of the water. They will not be affected differently because you are in a pool.

ICDs are programmed to meet a person’s needs. Typically, an ICD will be set to deliver 20-35 joules per shock. Talk to your doctor to discuss how your ICD is programmed.

The amount of battery used to deliver a shock depends on the specific ICD manufacturer and model, as well as the amount of energy your device is programmed to deliver. When longevity is estimated for ICDs, the frequency of device charging is included.

Most people are aware of receiving an ICD shock. Those who are conscious during a therapy shock most commonly describe it as a sudden thump or kick to the chest. The sensation startles them, but passes quickly. Some find it brief but distressing; others find it reassuring that the device is doing its job. Some people lose consciousness during a rapid arrhythmia and are not aware they received a shock at all.

Your ICD clinic or cardiac nurse should give you a written shock plan before you leave hospital after implantation. This sets out exactly what to do if your device delivers a therapy shock. If you have not received one, ask for it at your next clinic appointment.

In general, if you receive a single shock and feel well immediately afterwards, contact your ICD clinic the same day or the next working day so the episode can be reviewed by downloading your device data. If you receive two or more shocks in quick succession, feel unwell after a shock, or the shock does not resolve your symptoms, call 999 immediately.

If you are unsure what to do in any situation, contact your ICD clinic. Most clinics have a dedicated number for urgent queries during working hours, and you should be given a number to call out of hours.

Each patient describes an ICD shock differently. Some say it feels like a thump on the chest while others compare it to being kicked in the chest. It is normal to feel apprehensive, but also remember that a defibrillating shock from an ICD can be lifesaving. For most people, if there is pain, it quickly passes.

Your ICD is designed to deliver therapies that progress from the mildest form to be effective to an actual shock. If you receive a shock from your ICD, you will feel an obvious electrical jolt to your body, but each patient describes an ICD shock differently. Some say it feels like a thump on the chest, while others compare it to being kicked in the chest. It is normal to feel apprehensive, but also remember that a defibrillating shock from an ICD can be lifesaving. For most people, if there is pain, it quickly passes.

Phones, which use wireless signals, have electromagnetic fields around them. Some of these fields may affect the normal operation of your heart device. Your phone should be kept at least 6 inches away from your device.  When using a mobile phone, it is best to hold it to the ear that is farthest away from your heart device. Also, is a good idea to avoid carrying your phone in a shirt pocket that is close to the ICD.

If you receive a therapy shock, anyone touching you may feel the shock as a muscle spasm or a tingle, although it is unlikely. A therapy shock can be startling, but it will not hurt a person touching you.

No. You will not receive a warning from your ICD before a shock. However, you may have symptoms that tell you a shock may be imminent.
Symptoms may include dizziness, lightheadedness, or a fluttering in the chest.

No, your ICD will only shock you if it detects a heart rhythm that is too fast.

No, your ICD is designed to deliver a shock to treat heart rhythms that are too fast.

A momentary shock will not permanently damage your ICD. A memorable (longer) shock may cause some ICD settings to be reset to nominal values. Your doctor can restore your individual settings in the clinic.

No. The tiny electrical current produced by a novelty hand buzzer or similar toy is far too weak to interfere with an ICD. There is no clinical evidence that these devices pose any risk to implanted cardiac devices.

If you have any concerns about a specific device or situation, contact your ICD clinic for reassurance.

Your doctor will know if you recieve a shock as the ICD records and stores data when therapy like a shock is delivered.

ICDs deliver shocks to save your life when pacing therapies don’t return your heart to a normal rhythm. After a successful shock, your normal heart rhythm will resume.

An ICD can be programmed to deliver several types of therapies.  They can act as a standard pacemaker, deliver high-energy shocks, and deliver rapid pacemaker-like therapy to break up fast heart rhythms.

If at any time you receive an appropriate shock from your ICD i.e. one that is correcting a potentially fatal arrhythmia, you must surrender your licence and stop driving for 6 months.  

If you were incapacitated i.e. went unconscious whilst you received the shock the suspension is 2 years. This may be reduced to 6 months if your cardiologist takes steps to prevent any further events requiring a shock eg starting or adjusting medications.

If you receive an inappropriate shock i.e. the shock was unnecessary, then you will receive a 1 month suspension.

If you are driving whilst you receive a shock you should stop as soon as is safe to do so, and should not continue until the cause of the shock has been investigated.

For more information about shocks see our ICD shocks page.