We have great machines for shocking a heart out of various malfunctions.

But my understanding is that the only "machine" indicated for restarting a heart that has completely stopped (i.e., "flat-lined") is manual compression. I.e., even if you're a patient in a Level 1 trauma center, if you flat-line then all the machines get pushed aside and one person is going to start pushing on your chest above your heart to try to get it started. (And you might get a does of epinephrine. Oh, and if you're really "lucky" and they have your chest torn open then they'll reach in and compress the heart directly.) Is this accurate?

If so, isn't this weird? Pushing on the heart through the rib cage to get it to spontaneously start seems like trying to rescue someone drowning by standing on the shore and poking them with a stick.

We can electrically stimulate every muscle to contract. I understand that a functional heartbeat requires a coordinated series of contractions. An electrocardiogram can monitor the sequence of contractions in a functional heartbeat. Why can't it (or something like it) pump current back through its electrodes to stimulate a perfect heartbeat?

Or, if one could place arbitrary electrodes directly on a heart, could an electronic device force it to beat – indefinitely – when it has flat-lined? Or is there some reason that is not technically or medically feasible?

Again, it just seems weird that when the heart stops the current best practice is basically to just try "nudging" it to start.

  • You are describing a pacemaker. Precisely why we can pace bradycardia but not asystole is a good question.
    – Susan
    Commented May 27, 2016 at 13:22
  • @Susan - Exactly, hope it's clear that's my question. I.e., "Got an arrhythmia, fibrillation, or any other heartbeat malfunction? No problem! This tiny electrical jolt will get you back on track. But heart stopped altogether? All we can do it physically pound on it and see if it decides to start again!"
    – Lysander
    Commented May 27, 2016 at 14:47
  • The contrast of interest, in my mind, is not between defibrillation (for VF/VT) and lack thereof (for asystole) but between pacing (for bradycardia) and lack thereof (for asystole). Defibrillation depolarizes the muscle to momentarily stop conduction and terminate an arrhythmia -- it's obvious why this isn't helpful for asystole (cf. Why is defibrillation in asystole (“flat line”) useless?). But pacing.... I've always wondered exactly how long the pause needs to be before you call it "cardiac arrest" and therefore can't pace.
    – Susan
    Commented May 27, 2016 at 15:13
  • (P.S. CPR is not generally expected to coax the heart into restarting. It only maintains a semblance of circulation while hopefully some other intervention is offered.)
    – Susan
    Commented May 27, 2016 at 15:15
  • @Susan Are pacemakers only for bradycardia? I thought there were some implantable devices that could also treat fibrillation. In any case, it would be great to get a cardiologist to weigh in here. For example, there are surgeries during which the heart is stopped and later restarted: How? And going back to the trauma case: If they actually have the chest cavity open and the heart stops why do they manually compress it instead of strapping on emergency "pacemaker" electrodes to stimulate it through a perfect heartbeat? (Also, if CPR and epinephrine don't fix asystole, what intervention can?)
    – Lysander
    Commented May 27, 2016 at 15:38

1 Answer 1


"Giving" electrical current to the heart does not necessarily translate to mechanical contractions. The excitation-contraction coupling (as the sequence of electrical activation an muscle contraction is officially called), is not always a guarantee.

A cardiac arrest in many cases mirrors severe malfunction on the level of the micro-structures of the heart and a biochemical disarray in general. If you don't restore the pumping of the heart in seconds to minutes (even if this is crude and primitive-looking), the patient may not only die, but even worse they may "live" with severely depressed or completely absent brain function.

The only way, a "modern" way would help a "stopped" heart is if some futuristic nano-device could be employed rapidly to either correct micro anatomy and microphysiology in minutes, or replace and collaborate with the patient's native structures.

However, primitive it may seem to you, external manual compressions, if properly performed can make the difference (at a great percentage) between life and death.

The "electrical current- modern" approach works for patients with severe arrhythmias or conduction problems. In these cases the "mechanical part" of the heart is intact and you only replace the electrical function of a problematic conduction system or problematic natural pacemakers.

Even in this case, a properly performed placement of a temporary pacemaker is an awkward process that can take several minutes until successful (transcutaneous or transvenous) placement is established. If the patient is asystolic or almost asystolic (no-pulse), "primitive" compressions should be done until the pacemaker safely paces.

Unless a super enhanced swarm of nano-machines, that can navigate safely through the human body and correct problems rapidly and at will, emerges, no "sophisticated machines" will replace manual compressions. In fact, during resuscitation they have been proven much more valuable than artificial breathing, which is reflected in the change in the guidelines during the past 15 years.

Algorithms for Advanced Cardiac Life Support 2015

Acute treatment of sustained ventricular arrhythmias

  • Thank you for your answer! If I'm understanding you correctly: The heart is such a durable organ that it takes a severe disruption to produce asystole, and those disruptions can't simply be overridden by even a complex sequence of artificial electrical stimulii? I am guessing this is because asystole only occurs if the muscle itself is impaired -- e.g., via heart attack?
    – Lysander
    Commented Jul 23, 2016 at 21:34
  • @Lysander Yes, the answer is that use of electrical current is only beneficial under certain circumstances in cardiac arrest, for example in an arrhythmia called ventricular fibrillation. In some cases only a forced brutal attempt will restore the mechanical function of the heart, fast enough to be beneficial for the patient, that is mechanical compressions. Commented Jul 24, 2016 at 13:25
  • This is a very good answer and I do believe that you are a cardiologist, but we have a policy of requiring references. Adding references would enhance this answer a lot and make the information much more useful to this site and the internet as a whole. Thanks :)
    – michaelpri
    Commented Jul 24, 2016 at 16:55
  • So, a gross verification of what I say can be found on acls.net/aclsalg.htm the site of ACLS, and the latest guidelines for sudden death from the european society of cardiology especially on the section 4.4 m.eurheartj.oxfordjournals.org/content/36/41/2793.full. I will be providing more detailed references next time. Commented Jul 24, 2016 at 22:47
  • I've edited those sources into your answer. Thanks.
    – michaelpri
    Commented Jul 25, 2016 at 20:31

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