So if a heart stops you can massage, pump or shock it back to life, and surgeons even stop a heart on purpose before firing it back up, so why can’t they do that 100 percent of the time? What is it that makes a heart stop and never come back? If the brain is working then surely the heart should always come back?
In: Biology
Technically, we can. The heart isn’t necessarily the issue. We just need the heart so it can get oxygen to the head and get the brain back online. If the brain won’t come back, then it can’t pick up the slack and take back reigns of keeping the heart pumping. The heart can’t force the brain to cooperate.
Simple answer: Hearts stop for different reasons. The methods you mention work for some of those reasons and not all. Often it depends how damaged the heart is, but sometimes just the way it’s damaged.
By analogy, if people keep their cars from stopping by putting gas in them – I see people put gas in their cars to make them run every day – then why do some cars stop even with gas in them? Why doesn’t putting gas in all broken cars make them able to go again?
There are lots of things that can cause a heart to stop. It can be internal bleeding, lack of oxygen to the heart muscles, neurological issues, various drugs, etc. It is not possible to start a heart without fixing the reason it stopped. And once you have solved this the heart will usually start on its own without any help.
The problem is that a stopped heart will not pump blood around the body and will therefore not provide itself with oxygen and eventually the neurons and other cells start to die. It is therefore very important to start chest compressions as soon as possible to manually pump blood around the body. In some rare cases the body is able to fix whatever is wrong on its own and the heart will start but this is very rare and most of the time you need to do chest compressions until a doctor is able to fix whatever is wrong.
You may have seen defibrillators being used. This is very commonly seen in TV and movies. There is a trope that a defibrillator can start a heart but this is not the case. The heart may go into fibrillation where the heart muscles gets out of sync. This means the heart is not working well if at all. It is still alive and moving but is not pumping blood around the body. There may be several different reasons for this to occur. It can happen as the heart is starting up but it is usually caused by other things. The defibrillator is used to fix the fibrillation. But it is not used when the heart is not beating.
If your hearts stops beating there is normally a reason for it (e.g. something is damaged). And depending on what the reason is, you will not be able to “restart” it (or at least not for long).
As an analogy: If you have a car, where the battery is empty, you can jump start it using another car. But that will not work, if the motor of your car is broken. Trying to jump start your car then might be able to rotate the motor for a quick motor, but you will not be able to drive with it.
Essentially, you can’t reliably “restart” a heart if it’s so diseased that it won’t work on its own any more.
When surgeons restart a heart after surgery, it’s because the heart was healthy enough before the surgery to beat on its own. The surgeons stopped the heart using a drug, and then stop the blood flow to the heart so that the drug stays inside. When they are done, they reestablish the blood flow, so the drug is washed out. Typically the heart will just start again on its own.
If the heart doesn’t start back up on its own, or it starts with an abnormal rhythm, massage and electric shocks can try to reset it, hoping that it will resume its work again.
But that’s basically just giving the heart a little nudge and telling it “Hey, wake up, please keep working!”
But if the heart is so diseased that it won’t work on its own, you can’t force start it. Nothing will help.
As for what could be wrong to make the heart not work anymore? Many things can be wrong. Diseased heart muscles, a diseased sinoaterial node (the thing that gives the rhythm), diseased valves, etc.
To add to what others and maybe elaborate on part of your question. When someone dies and is shocked their heart isn’t exactly “restarted”. If someone receives a shock its because their heart is in a rhythm that doesn’t pump blood very well. The shock attempts to correct the rhythm and make it pump correctly again.
When doctors stop a heart deliberately, they do it in a way that is reversible, without lasting damage. When hearts stop by accident, this usually stops oxygen flow to (parts of) the heart, while the heart is still trying to do its work. So the heart uses up oxygen and chemical energy, but those reserves aren’t getting replenished (because no blood is flowing), and so the heart cells are getting starved and this may cause cell death. Too much cell death can mean the heart is unable to restart.
When doctors stop a heart during surgery, they truly stop it. They pump a solution into the heart that causes it to stop beating altogether and reduce its metabolism to a minimum. This protects the heart from cell death, because while it is not receiving fresh oxygen & energy, it is also not using much.
Your brain doesn’t control your heart. The heart has its own little nerve centers that generate the electrical impulses that cause the heart to beat, with all the different compartments contracting in the correct order, to the correct rhythm. If your brain is still working, that doesn’t mean your heart has to be too.
Your heart needs oxygen. If something prevents oxygen getting to the heart (loss of blood, blocked artery etc.) then it runs out of oxygen and physically can’t beat anymore.
In theory you could sit there squeezing it to pump blood but the thing stopping your heart from getting oxygen is probably affecting the rest of your body’s ability to get oxygen as well.
Defibrillation will only shock 2 heart rhythms, Ventricular Tachycardia (V Tach), and Ventricular Fibrillation (V Fib). Any other rhythms have to be medically cardioverted using drugs and other interventions.
To quote my sons heart surgeon. “Hearts want to be pumping. Like really bad. It is harder to stop a heart than get it to start back up.”
When my son was born he had a 9mm hole between two ventricles in his heart. Meaning oxygenated blood was flowing back into the non-oxygenated blood, and circulating back through the lungs again. This occurs in 1/500 births…which is SHOCKINGLY common IMO. He lived with this for 6 months so he could put on some weight before the surgery. Anyway. They had to stop the little dudes heart and put a patch on the hole. The only thing they had to do to get the heart to start back up was start blood flow and a bit of electrolyte solution. It started pumping happily without issue.
A defibulator, the zappy zap zap machine with the paddles, that usually isn’t there to “restart” a heart. It is there to slap it back into proper rhythm. Imagine a car engine with mistimed cylinders. It can still run, but it is not doing a great job and will most likely damage itself soon. Same concept. The defib is there to pause the heart for a moment so it gets back into a good rhythm. Most defibs you find in public places will actually check first to see if the heart rhythm is improper and won’t fire unless it matches predetermined bad patterns.
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