# Why doesn't shocking someone that's flatlined work? **URL:** \ **Category:** Factual Questions\ **Created:** [July 26, 2017, 3:18pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165 "2017-07-26T15:18:17Z")\ **Posts on this page:** 9\ **Page:** 2
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [July 27, 2017, 1:18pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/21 "2017-07-27T13:18:15Z")
The paddles for starting a heart in an open chest cavity are quite different from the big pads used to defib someone. Applied directly to opposite sides of the heart. And not just any heart, one that was deliberately stopped with the cause of the stoppage no longer (hopefully) in effect. ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [July 27, 2017, 2:28pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/22 "2017-07-27T14:28:51Z")
Because the cause of the flatlining is not just the heart malfunctioning. The heart is not getting a signal to beat from the brainstem. . . Or not enough oxygen is in the blood to sustain it. . . Or too much toxic waste has built up in the blood due to failure of some other organ . . Or a blood vessel is so blocked that the heart tissue is necrotic . . . such that the cells can’t function normally even if you could get a pacemaker in there on time. Something else is happening, and so just getting the electrical signals to the heart back in order won’t fix the problem. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [July 27, 2017, 3:13pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/23 "2017-07-27T15:13:19Z")
> [@TruCelt](#): > > The heart is not getting a signal to beat from the brainstem. . . The heart doesn’t get its signal from the brainstem. If it did, heart transplants wouldn’t work since the nerves are severed during the process. The heart gets its signal from the SA node at the top of the heart. This is the heart’s “pacemaker”, if you will. The atria (upper chambers) of the heart contract. A short time later, the electrical signals from the SA node reach the AV node further down in the heart, and the AV node fires off, causing the ventricles (lower chambers) to contract, completing the pumping cycle. The SA node keeps sending out pulses at the appropriate time, triggering each cycle. The SA node controls everything, not the brain stem. The brain can send signals to the heart through nerves which can make the SA node speed up or slow down, and various hormones and chemicals (like adrenaline released from the adrenal glands) can also affect the SA node’s pace. People who have had heart transplants have to be careful because the nerve connections to the heart have been severed, so that regulation method for the heartbeat no longer works. They might pass out if they exert themselves too much too quickly, since without those nerve connections the heart is much slower to respond to things like exertion and stress. ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [July 27, 2017, 3:32pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/24 "2017-07-27T15:32:13Z")
> [@engineer\_comp\_geek](#): > > The heart doesn’t get its signal from the brainstem. If it did, heart transplants wouldn’t work since the nerves are severed during the process. > > The heart gets its signal from the SA node at the top of the heart. Ignorance fought. But it also supports my overall point. ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [July 27, 2017, 3:32pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/25 "2017-07-27T15:32:29Z")
> [@ftg](#): > > The paddles for starting a heart in an open chest cavity are quite different from the big pads used to defib someone. Applied directly to opposite sides of the heart. And not just any heart, one that was deliberately stopped with the cause of the stoppage no longer (hopefully) in effect. Well, they’re smaller and use less power if that’s what you mean. ---
**Author:** ![x-ray\_vision](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/x-ray_vision/32/351_2.png) [@x-ray\_vision](https://boards.straightdope.com/u/x-ray_vision)\ **Post date:** [July 27, 2017, 4:34pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/26 "2017-07-27T16:34:04Z")
> [@engineer\_comp\_geek](#): > > If you are flatlined, the SA node is no longer working. It doesn’t matter what you do at that point. I’m not sure that’s true. From an old post by Cheif Pedant: > [@](#): > > That patient is “flatline” because the cardiac monitor shows no electrical activity at all. Using a countershock on such a patient will not generate a heartbeat. Treatment for asystole includes various drugs and/or pacemakers, and in the setting of a typical cardiac arrest is not usually effective, either. [http://boards.straightdope.com/sdmb/showpost.php?p=13548555&postcount=37](http://boards.straightdope.com/sdmb/showpost.php?p=13548555&postcount=37) > [@](#): > > Of those with PEA/asystole arrests, 15% survived to discharge if not on pressors at time of arrest. Only 6% survived if on pressors > **[PulmCCM | Substack](https://www.pulmccm.org)** > > Life, death and the ICU. Click to read PulmCCM, a Substack publication with tens of thousands of subscribers. It could be that all the above cases resulted in survival because what was reading on the monitor as asystole was incorrect, but I’m just guessing. ---
**Author:** ![TXCowboy](https://avatars.discourse-cdn.com/v4/letter/t/76d3ee/32.png) [@TXCowboy](https://boards.straightdope.com/u/TXCowboy)\ **Post date:** [July 27, 2017, 5:58pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/27 "2017-07-27T17:58:05Z")
Maybe just a TV/movie thing but Sometimes (usually doing a transplant) start the blood flowing back and the heart just sitting there, then the surgeon "thumps " the heart with his finger and it starts beating. Real or not? ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [July 29, 2017, 12:08pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/28 "2017-07-29T12:08:48Z")
> [@TXCowboy](#): > > Maybe just a TV/movie thing but Sometimes (usually doing a transplant) start the blood flowing back and the heart just sitting there, then the surgeon "thumps " the heart with his finger and it starts beating. Real or not? [https://en.wikipedia.org/wiki/Precordial\_thump](https://en.wikipedia.org/wiki/Precordial_thump) Supports the suggestion that surgeions defib after heart transplant or surgery. (I know lots of odd bits of medicine, but not about surgery ) I was on a bus once that stopped and off-loaded a teenager. One of my acquaintances had been sitting next to the guy, and applied a precordial thump when he went into fibrillation. I guess it worked, because the guy recovered consciousness and was med-evac’d. ---
**Author:** ![clairobscur](https://avatars.discourse-cdn.com/v4/letter/c/839c29/32.png) [@clairobscur](https://boards.straightdope.com/u/clairobscur)\ **Post date:** [July 29, 2017, 2:07pm UTC](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165/29 "2017-07-29T14:07:30Z")
> [@Melbourne](#): > > [https://en.wikipedia.org/wiki/Precordial\_thump](https://en.wikipedia.org/wiki/Precordial_thump) > > I was on a bus once that stopped and off-loaded a teenager. One of my acquaintances had been sitting next to the guy, and applied a precordial thump when he went into fibrillation. I guess it worked, because the guy recovered consciousness and was med-evac’d. One of my brothers (mountain guide) did it once successfully on one of his clients. The wikipedia article mentions however that it was apparently taught in the past in CPR training, and discarded later because it resulted more often in further damages than in restarting the heart (although I’ve always been told that when someone is fibrillating, you shouldn’t be too bothered about the damages you could cause, since you can hardly make the situation any worse). [Previous page](https://boards.straightdope.com/t/why-doesnt-shocking-someone-thats-flatlined-work/792165.md?page=1)