I am confused about whether the heart stops beating during cardiac arrest or not. The answer in this question states, "the heart does not pump blood sufficiently to sustain life." Isn't that the definition of heart failure? This article states that a flat-lined heart can not be revived. However, in the case of cardiac arrest, the patient's heart can be revived. If this article is correct, then the heart does not stop beating aka flat lines when it is in cardiac arrest. However, in this article, it is clearly stated that the heart stops beating during an ongoing cardiac arrest.

So, which is correct? Does the heart stop beating during a cardiac arrest, or no? If it does stop beating, how is that not the definition of death? Does a person have any consciousness in this time? Do they have an neurons firing in the brain? Since the brain doesn't die a few minutes after death, is the person able to hear, feel pain, think or feel any stimulus while they are in cardiac arrest?

  • 1
    Yes, the heart stops beating effectively during cardiac arrest. Not beating effectively doesn't necessarily mean it's at a standstill, but only that it's not pumping blood sufficiently to keep you alive. A CPR course would clarify this for you.
    – Carey Gregory
    Mar 5, 2018 at 4:56

1 Answer 1


No, a heart does not necessarily stop beating during cardiac arrest. Cardiac arrest occurs any tine the heart cannot pump blood to the brain at a rate/volume sufficient for the patient to remain conscious.

From your second link:

To understand SCA [sudden cardiac arrest], it helps to understand how the heart works. The heart has an electrical system that controls the rate and rhythm of the heartbeat. Problems with the heart's electrical system can cause irregular heartbeats called arrhythmias.

There are many types of arrhythmias. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. Some arrhythmias can cause the heart to stop pumping blood to the body—these arrhythmias cause SCA. [emphasis mine]

A patient can be in ventricular tachycardia (VT or Vtach) and still be awake. If they are, they are in Vtach, and treated as such. If their Vtach is in fact enough to cause compromised flow to the brain and the patient passed out, it's a cardiac arrest.

Congestive heart failure is a different animal.

The heart has cells which are supposed to fire synchronously. This is what allows the heart to pump effectively. Tachycardia means too fast, and if it's too fast, the ventricles can't fill enough to pump effective amounts to the brain. Fibrillation ("VFib") is when the cardiac cells which have some "pacemaker" activity are firing asynchronously, which means blood isn't getting pumped. The heart may not be beating in an organized fashion, but it's not at a standstill.

Administering a shock causes all of the units to fire at once (which causes a temporary asystole), in the hopes that when electrical activity resumes (after giving a shock, we wait and look at the monitor to see if there is a regular heart beat, we do not start CPR unless there is not), it will do so in an orderly, synchronous manner.

In asystole (flat line), there is no longer any effective electrical activity of the heart. There is basically no disorganized electrical activity to try to reset with a shock.

That is why it makes no sense to shock someone in asystole. On television, people in flatline are shocked into a stable sinus rhythm. That just doesn't happen in real life. Neither does a deep breath and fluttering open of eyelids, as often shown on television when someone arrests and resuscitation is successful.

Asystole @ Medscape.com
Treatment of Asystole @ Medscape.com

  • Excuse my ignorance, what does vtach stand for?
    – user12041
    May 8, 2018 at 19:41
  • @Stacey - Sorry, I clarified in the edit. Thanks. May 8, 2018 at 20:24
  • My training was that being pulseless in VT is what makes it an arrest, not being unconscious. Granted, pulselessness is likely to follow unconsciousness rather promptly, but shocking VT with pulses was generally frowned upon. Clarify?
    – Carey Gregory
    May 9, 2018 at 3:27
  • @CareyGregory - In over a thousand codes (key word, codes), I have never seen anyone in pusleless VT who was conscious, so please don't pick be picking at nits. That window is probably 30 seconds wide or less, because of the compromised cardiac function already present in VT. I have seen people go from VT with to without pulses. You know when it's happening because they become hemodynamically unstable. As soon as they are hemodynamically unstable, you shock.Treatment of VT (with pulses) is a different question, as it is not considered cardiac arrest at that point. It's VT. May 9, 2018 at 14:38
  • @anongoodnurse I wasn't trying to pick nits. Was truly just looking for clarification. I think your answer was exactly what I said so I guess I that clarifies.
    – Carey Gregory
    May 9, 2018 at 20:25

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