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Cardiac Arrest Symptoms

Signs and Symptoms of Sudden Cardiac Arrest

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Updated April 29, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Cardiac arrest is not only a medical condition -- it's also the same as clinical death. So technically, the easiest cardiac arrest symptom to describe would have to be "death."

However, when most people talk about cardiac arrest, we're talking about a treatable condition -- sudden cardiac arrest -- that we can recognize and potentially fix. Depending on the cause of cardiac arrest, the symptoms can mimic other conditions. Regardless of cause, the treatment for cardiac arrest always starts with CPR.

Symptoms of Sudden Cardiac Arrest

  • Sudden loss of consciousness: Cardiac arrest caused by a cardiac arrhythmia will suddenly stop blood flow to the brain, causing the victim to lose consciousness (pass out). This can also happen with a condition known as syncope, which causes fainting.

    The biggest difference between syncope and cardiac arrest is that syncope victims continue to breathe and usually wake up right away, while cardiac arrest victims don't do either. The good news is that research shows CPR does not hurt syncope victims (and might even help), so if you mistake syncope for cardiac arrest, it won't matter.


  • Not breathing: A few seconds after the heart stops pumping blood, the brain will stop telling the body to breathe. In some cases, there are gasping movements that look a little like a fish out of water (but don't really get any air in and out) called agonal respirations. As far as breathing goes, agonal respirations don't count. You will still do CPR on gasping victims.

  • No pulse: The lack of a pulse has traditionally been the gold standard sign of cardiac arrest. Unfortunately, it's difficult for lay rescuers to recognize a pulse -- or more accurately, it's difficult for lay rescuers to tell when a pulse is not there. Indeed, sometimes trained rescuers can't tell, either. That's why not having a pulse is last on the list -- use the other signs first. Lay rescuers are no longer supposed to check for a pulse.

The most important thing to take away from this is that if you have any concern that someone might be in cardiac arrest, call 911 and start CPR. If you are reading this while trying to decide if the person at your feet is in trouble, just call 911.

Signs That It's Not Cardiac Arrest

If you're not reading this while trying to save another human being and you're wondering how to tell if it's not cardiac arrest, here are a couple of telltale signs.

  • The victim wakes up: Cardiac arrest is permanent unless the victim is treated by another person. If the victim wakes up on her own, then they weren't in cardiac arrest. If the victim wakes up because you did CPR on him, after you get him to the hospital you can pat yourself on the back for a job well done and share your lifesaving story.

  • You think you are the victim: If you're still thinking, you aren't dead yet (remember, cardiac arrest is the same as clinical death). Indeed, if you're researching cardiac arrest on the internet, your heart is still beating.
Related Video
How to Perform Hands-Only CPR
How to Do the Heimlich Maneuver
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