Inappropriate Shocks

Within days of my implant, my ICD gave me about 8-10 inappropriate shocks.  It took the EMS to get them stopped.   I initially had no idea what to expect.  IT sounded like an a hot electrical wire touching another hot electrical wire. I was washing eggs in the sink and I thought that maybe a small appliance fell in the water.  Things were happening so fast that I could not reason what was going on. For me,   It was painful.  I have no idea if that is what an appropriate  ICD shock is all about.  I tried to find out what they were supposed to feel like but no luck.  Any feedback?  

Does anyknow if  shocks affect the heart, either appropriate or inappropriate?


I wish you well

by Gemita - 2020-10-09 15:54:17

Dear Sally,

8-10 inappropriate shocks must have been really painful, not to mention frightening.  You did so well to get help and I hope your ICD team have been informed and will make sure that you do not receive unnecessary shocks in the future.  

You ask some difficult questions and I hope ICD members will see your post and be able to help you.  What does a shock feel like?  Well you have certainly had a sample of what it feels like.   A friend of mine who has an ICD mentioned that an inappropriate shock felt more painful for her than an appropriate one, so if you have survived 8 or more inappropriate shocks, hopefully this is as bad as it gets?  

As to whether shocks affect the heart.  I would suggest that the "reason for an appropriate shock" is more likely to adversely affect the heart rather than the shock itself which after all is meant to prevent a dangerous rhythm disturbance from taking hold and causing worsening symptoms which could make say heart failure or another heart condition worse.  

It sounds to me as though you have many unanswered questions and when you feel stronger, I would go back to speak to your doctors.  I would ask why your inappropriate shocks occurred and what can be done to prevent this happening again.  You presumably have home monitoring so that your doctors can check any daily downloads to see what might be happening.  I would keep a note (time and date) of any symptoms you develop to share with your team until you are confident that all is working as it should.  I hope for the very best

Internal cardiac defibrillation won't damage your heart

by crustyg - 2020-10-09 16:10:25

The energy used for an external defib - up to 300J - is easily enough to cause some damage to the skin, hence the large paddle size and the conductive gel pads, where possible, to avoid the energy being focussed on too small an area.  They need to use a lot of energy to get enough into the heart tissue where it's actually needed.

An ICD already has direct access to the heart and uses a (comparatively) tiny discharge - perhaps 20-30J.

I imagine if you kept getting 5 to 8 shocks of 20-30J into your heart every day it would be possible to show some deleterious effects, but that's really pushing it.  I've found some animal work showing 40 sequential shocks not affecting the useful effect (life-saving) of a later shock.

Some contributors here have had a) ICD firings when awake, b) external cardiac defib when awake.  They aren't in a hurry to have the experience again, and describe it as very painful - but I suppose it depends on the nerve supply to the heart.  Post transplant folk don't get angina pectoris - there is no nerve supply to the heart.  The pain of an MI is frequently less in women than in men and no-one knows why.  So perhaps your ICD firing is less painful for you.

Hope they get the settings sorted out soon - assuming that these really *were* inappropriate shocks.

ICD shocks and effect on the heart.

by Selwyn - 2020-10-09 16:20:16

Folk have posted about ICD shocks on this forum for some time ( see search on the upper right).  Some are appropriate and some just seem inappropriate ( eg. many repeated shocks over 1/2 hour). Some people have severe pain, some don't. Some people are unconcious when shocked, others not.  Inappropriate shocks account for about one-third of all shocks. The overall annual inappropriate shock risk for a patient with an ICD is estimated at 7.5% of those.

Of course receiving a shock affects the heart; this is the purpose of having an ICD, the heart must have its correct rhythm restored or you cease to function ( at least when you receive an 'appropriate' shock.) About 1/3 of ICD folk have a life-saving shock within 3 years of implant. Thank you for the ICD!

When your heart receives a shock there is minor muscle damage to the heart  as measured  in the blood by a rise in some types of  cardiac enzymes. ( see ). I am unsure as to what the record is for shocks per 24 hours, however such folk are at risk of further heart problems and should receive a re-evaulation of their cardiac status at their clinic, as should anyone receivng a shock so that their medication and management may be tweeked to stop this event from happening. 

ICD shocks

by islandgirl - 2020-10-09 19:58:13

My life-saving shocks were not quite 3 1/2 years following a SCA.  I had begun to have runs of vtach and my EP was adjusting meds and ICD therapies.  Dec 2019 I had 4 appropriate shocks  for vtach, vfib, and asystole.  I became unconscious after the first shock and regained consciousness after the 4th.  The ICD saved my life.  

About 2 1/2 weeks ago I received 2 ICD shocks at home, alone, assumed unconsious after the first shock, but regained consciusness after the 2nd shock.  Transported to the local hospital, then transported to a hospital about 2 hours away where my EP works.  Mine were appropriate for Vtach.  A few days later, in the hospital, I received 4 additional shocks, the first one for vtach, I passed out, and the ICD paced me out of the arrhythmia.  The additional 3 shocks were for vtach as well but I became unconscious and was shocked when I was unconscious, witnessded by medical staff.  After meds, almost 1 1/2 weeks in the hospital with most in ICU, an ablation, control of heart failure, my vtach episodes have disappeared.  

They are extremely painful.  I also realize that my ICD shocks have saved my life.  

Long story short, I have not received any inappropriate shocks.

Good luck.


by AgentX86 - 2020-10-10 01:09:20

Just to elaborate on what Crusty said, above.  An external cardioversion (DCCV) or defibrillation can be between 100 and 300 Joules.  It's not at all unusual to have skin burns after.  The pads are stuck to the chest and back so the DC current passes through the heart, as much as possible.

I've had a number of cardioversions, mostly at 100J but also at 300J.  I can tell by the size of the burn now.  ;-)  If the burn is in the outline of the pad, it was 100J.  If it's burned across where the entire pad was, it was a 300J cardioversion.  The burns weren't severe, more like a sunburn.  They didn't hurt but itched like crazy.

I was awake for one of them (after my second ablation).  They thought I was under but found out differently when a curse was made on their ancestors.  They didn't think I'd remember, either.  Wrong.  I saw nothing but red when it hit.

An AED could easily be worse than a cardioversion because the "paddles" are smaller and applied to the chest, rather than chest and back.  They may not make appropriate contact, either, because of the emergency situation.  A cardioversion is a comparitively leisurely procedure and there is plenty of time to place the pads appropriately.

In comparison to the 100 to 300J of an external cardioversion or defibrillation, an ICD will only use 5J, or so, when doing a DCCV, and 30J to ~40J during a defibrillation.  Depending on the arrhythmia an ICD may attempt to pace out of it, do a DCCV, a defibrilation, or any combination.


by Katelyn - 2020-10-30 00:35:14

After my 6 inappropriate shocks when i was alone, the following months i suffered from PTSD, and it took too much suffering until I realized it and seeked help.  pay attention to this, and seek therapy if needed- it really helped

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