# Heart Attack vs Cardiac Arrest



## helicub81 (Jul 20, 2011)

I was wondering what the difference was between a heart attack and a cardiac arrest.  My understanding is that a heart attack is cause by a physical obstruction which leads to the heart muscle not getting enough blood and oxygen while the cardiac arrest is more of an electrical problem which causes an inadequate supply of blood to the heart.  

That said, is someone who is having a heart attack (assuming that he is unconscious and pulse less) in aystole, which means that an AED will not work on him?


----------



## MrBrown (Jul 20, 2011)

The two terms are interchangeable in the minds of the lay person but this is not medically correct.

A "heart attack" (myocardial infarction) is localised cell death due to inadequate blood supply (ischaemia).  The main cause is coronary arteries occluded by plaque however there are other causes. 

In cardiac arrest the heart has "short circuited" and is not pumping.  The main cause of cardiac arrest is dysrhythmia and in the setting of sudden cardiac arrest, the leading cause of dysrhythmia is infarction.

To answer your question, somebody who is unconscious with no pulse is in cardiac arrest, not having a heart attack.  If the rhythm is VF or VT yes the AED will shock it, for asystole and PEA no


----------



## Imacho (Jul 20, 2011)

A heart attack is known as a myocardial infarction. the heart tissue is dying. it is not receiving the oxygen and nutrients to meet the demand of the heart. this is caused by a block in the coronary arteries. the infarct site will be shown on the 12 ECG by ST Elevation in certain Leads. The cath lab is definitive treatment for this pt. Arrest is complete failure of the electrical system. you'll see V-Fib or V-tach w/out pulses, on the monitor, both of which you can defibrillate. Asystole you can't. just do compressions and push epi and atropine every 3-5 minutes.


----------



## JPINFV (Jul 20, 2011)

Imacho said:


> A heart attack is known as a myocardial infarction. the heart tissue is dying. it is not receiving the oxygen and nutrients to meet the demand of the heart. this is caused by a block in the coronary arteries. the infarct site will be shown on the 12 ECG by ST Elevation in certain Leads. The cath lab is definitive treatment for this pt. Arrest is complete failure of the electrical system. you'll see V-Fib or V-tach w/out pulses, on the monitor, both of which you can defibrillate. Asystole you can't. just do compressions and push epi and atropine every 3-5 minutes.



Not all MIs are STEMIs and NSTEMIs (non-STEMI) are more often than not treated outside the cathlab. They also, as the name suggests, lack ST elevations. This is why titers, not 12 leads, are used to rule out acute MIs, and are followed by extensive other tests, like stress tests.


----------



## JPINFV (Jul 20, 2011)

MrBrown said:


> In cardiac arrest the heart has "short circuited" and is not pumping.  The main cause of cardiac arrest is dysrhythmia and in the setting of sudden cardiac arrest, the leading cause of dysrhythmia is infarction.



PEA is not necessarily a short circuit, and to expand, not all short circuits cause cardiac arrests.


----------



## Imacho (Jul 20, 2011)

ya i know. im being general and to the point for his original q.


----------



## MrBrown (Jul 20, 2011)

JPINFV said:


> PEA is not necessarily a short circuit, and to expand, not all short circuits cause cardiac arrests.



Correct you are sir, PEA is a mechanical problem not an electrical problem nor do all short circuit cause cardiac arrest

Semantics Brown supposes for better understanding?


----------



## Handsome Robb (Jul 20, 2011)

I would tentatively site SVT, Atrial rhythms, Junctional Rhythms and Bundle Branch Blocks as examples of short circuits, just to name a couple off the top of my uneducated head.


----------



## helicub81 (Jul 20, 2011)

Wait, so someone whose heart has stopped because he or she has had an heart attack, does that imply that if you put a 12 lead on, the monitor would register asystole?  Which is not shockable?  Or is that not always true?


----------



## Handsome Robb (Jul 20, 2011)

If someone is in cardiac arrest (think no pulses and no spontaneous breathing) your not going to take time to put a 12-lead on them.

And no asystole is never a shockable rhythm. Your heart can stop for reasons other than a heart attack.


----------



## helicub81 (Jul 20, 2011)

my bad about the 12 lead.  I'm an emt in the moment so i may get the terms wrong.  I get that there are several reasons that a heart can stop, but does someone who is pulseless due to a heart attack register as aystole on a monitor?


----------



## Aidey (Jul 20, 2011)

Someone who is in cardiac arrest is likely to be in one of 4 types of rhythms. PEA, V-Tach, V-Fib and asystole. Just because someone does not have a pulse does not mean that they will be in asystole. Someone who has had an MI will not automatically be in asystole. 

The rhythms generally defined as PEA are not shockable, and asystole is never shockable. It would be like hitting the reset button on a computer that isn't plugged into the wall outlet.


----------



## Handsome Robb (Jul 20, 2011)

They can register in a couple different rhythms. Asystole being one of them. The other rhythms would be Ventricular tachycardia, ventricular fibrillation, and Pulseless Electrical Activity.

Edit: bah Aidey beat me to it!


----------



## JPINFV (Jul 20, 2011)

PEA is not a "rhythm," but a state of being. A patient can, however unlikely, show a normal sinus rhythm and be in PEA. PEA is simply any electrical activity outside of v-tach and v-fib (asystole is a -lack- of electrical activity) that lacks a pulse. Personally, and while I'm not old enough to be aorund when it was in use, I do like the old "electromechanical dissociation" as a better description.


...and to clarify something, it's always appropriate to tone down a description to make sure that the point gets across, provided it's accurate.


----------



## Aidey (Jul 20, 2011)

I did say "the rhythms generally defined as PEA", indicating that it isn't a rhythm in its own right so I get 1/2 credit.


----------



## JPINFV (Jul 20, 2011)

Aidey said:


> I did say "the rhythms generally defined as PEA", indicating that it isn't a rhythm in its own right so I get 1/2 credit.



Is that like discussing the artist formerly known as Prince?


----------



## the_negro_puppy (Jul 20, 2011)

Blame the media and shows like House for using the term "heart attack" to describe cardiac arrest. Even in my city last weekend a rugby player suffered a fractured C-spine and a head injury and had his life support in hospital. The media and newspapers reported he had a 'heart attack' after a bad tackle.

Put simply heart attacks and many other things cause the heart to stop, which is cardiac arrest.


----------



## firecoins (Jul 20, 2011)

cardiac *arrest* as indicated by the word arrest is not adequatley pumping blood.  Similarly to respiratory arrest where some has pretty much ceased breathing.  

A heart attack/MI need not cause someone to go into cardiac arrest.


----------



## Sasha (Jul 20, 2011)

A heart attack is your heart going "AAAHHH CRAP IM NOT GETTING BLOOD FLOW AND THEREFORE OXYGEN"

Cardiac arrest is you're heart going "Eff this i'm done, peace out homies!"


----------



## Shishkabob (Jul 20, 2011)

JPINFV said:


> A patient can, however unlikely, show a normal sinus rhythm and be in PEA.



Had one.  Score!


I always get the damn rarities...

V-tach with a pulse... V-tach with a pulse during an MI... Normal sinus PEA...yeesh.


----------



## medicdan (Jul 20, 2011)

OP, everyone dies of cardiac arrest. Sorry. Cardiac arrest simply means the heart has stopped, or is in an unproductive rhythm (Ventricular Tachycardia, Ventricular Fibrillation, Pulseless Electrical Activity, Asystole, etc)
In a "Heart Attack", initially, the heart is functioning normally, but as the blockage of blood supply to the muscle itself intensifies, if untreated, the muscle malfunctions, causing the unproductive rhythm, and leading to unresponsiveness and eventually asystole (cardiac arrest).

Just trying to keep things simple for our (untrained) OP.


----------



## Shishkabob (Jul 20, 2011)

emt.dan said:


> OP, everyone dies of cardiac arrest.



Actually, everyone dies of shock.  h34r:


----------



## STXmedic (Jul 20, 2011)

Sasha said:


> A heart attack is your heart going "AAAHHH CRAP IM NOT GETTING BLOOD FLOW AND THEREFORE OXYGEN"
> 
> Cardiac arrest is you're heart going "Eff this i'm done, peace out homies!"



Win. Taken straight outta the text book!


----------



## Sasha (Jul 20, 2011)

Linuss said:


> Actually, everyone dies of shock.  h34r:




Everyone dies of anoxia.


----------



## jjesusfreak01 (Jul 20, 2011)

Sasha said:


> Everyone dies of anoxia.



Everyone dies of cessation of brain activity...whatever the cause may be.


----------



## Sasha (Jul 20, 2011)

jjesusfreak01 said:


> Everyone dies of cessation of brain activity...whatever the cause may be.



Anoxia. Your cells die because they can no longer recieve oxygen.


----------



## mycrofft (Jul 20, 2011)

*OP, another take.*

"Heart attack" is for lay persons. We use "chest pain" (a subjective complaint) in the absence of vital signs or EKG.

An infarction is explained above and diagnosed with EKG. Other than the administrtion of aspirin per local protocols, that is not of use to basic field people. It *is* to advanced life support types.

As a basic, you are going to have conscious people with c/o chest pain and with a pulse; unconsicous people with a pulse; unconscious people with no pulse.

A regular pulse with adequate BP (conscious or not) suggests but does not rule out an infarction. (There are also transient heart pains which can herald a likelihood of infarct in the near future).

An irregular pulse in a conscious or unconscious patient can mean longstanding or acute trouble. When coupled with chest pain, syncope, etc.,act calmly and reassuringly and get on with the likelihood of an issue needing the full meal deal, including ASA (since irregular heart activity can cause clotting which can lead to MI or CVA).

Absence of palpable pulse can mean the heart has stopped, or it is pumping so ineffectively that you can't feel it. Either way, anoxia is whittling away at the pt and you need to start CPR, get EMS going, get an AED on the pt. The AED may say "Shock not advised, continue CPR"; do it.


----------



## mycrofft (Jul 20, 2011)

*OOOPS, correction to above.*

INstead of:
"A regular pulse with adequate BP (conscious or not) suggests but does not rule out an infarction", read the following:

"* A regular pulse with adequate BP (conscious or not) does not rule out an infarction, but suggests some other cause*".


----------

