Table of ContentsView AllTable of ContentsEffects of Cardiac Arrest on the BrainBrain Damage SymptomsBrain Activity With ComaReperfusion Injury
Table of ContentsView All
View All
Table of Contents
Effects of Cardiac Arrest on the Brain
Brain Damage Symptoms
Brain Activity With Coma
Reperfusion Injury
Cardiac arrest (when the heart stops beating) interrupts circulation, causing brain cells to start dying in less than five minutes of the brain going without needed oxygen in the blood. The catastrophic effects of brain damage can prove fatal in a short amount of time.
The American Heart Association reports that more than 356,000 out-of-hospitalcardiac arrestsoccur in the United States each year. Nearly 90% of them are fatal.
This article explores what happens when cardiac arrest causes brain damage due to a lack of oxygen, and the common symptoms seen when a person is revived. It also looks at problems that arise when blood flow begins again in tissues that are damaged.
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A person becomes unconscious quickly during cardiac arrest. This usually happens within 20 seconds after the heart stops beating. Without the oxygen and sugars it needs to function, the brain is unable to deliver the electrical signals needed to maintain breathing and organ function.
This can lead to ahypoxic-anoxicinjury (HAI). “Hypoxia” refers to a partial lack of oxygen, while “anoxia” means a total lack of oxygen. In general, the more complete the oxygen loss, the more severe the harm to the brain.
Signs and Symptoms of Sudden Cardiac Arrest
Timeline
When cardiac arrest occurs, cardiopulmonary resuscitation (CPR) must be started within two minutes. Effective CPR, if started immediately with a witnessed arrest can have positive outcomes.
If CPR is delayed more than three minutes,global cerebralischemia—the lack of blood flow to the entire brain—can lead to brain injury that gets progressively worse.
By nine minutes of delay, severe and permanent brain damage is likely. After 10 minutes, the chances of survival are low.
Even if a person is resuscitated, eight out of every 10 will be in a coma and sustain some level of brain damage. Simply put, the longer the brain is deprived of oxygen, the worse the damage will be.
It is rare for someone to be in a coma for longer than two to four weeks. However, there have been very rare cases of people who have stayed in a coma for years or even decades. Brain damage becomes more likely the longer that a person is in a coma.
Brain Damage Symptoms After Resuscitation
People are most likely to be successfully revived in a hospital or another site with quick access todefibrillators. These are devices that send electrical impulses to the chest to restart the heart. These devices are found in many workplaces, sports arenas, and other public places.
When a cardiac arrest is treated very quickly, a person may recover with no signs of injury. Others may have mild to severe damage.
For those who are resuscitated and not in a coma, hypoxia may cause:
Some symptoms may improve over time. Others, however, may be lasting and require lifelong assisted care.
Some 90% of people who go into cardiac arrest outside of a hospital—meaning at home, work, or wherever it occurs—will die.Good outcomes rely on witnessed arrest and early effective CPR. Never delay starting CPR with quality compressions, and calling for help, which includes a defibrillator and EMS.
People who are comatose after a cardiac arrest will often have damage to different parts of the brain, including:
Even the spinal cord will sometimes be damaged.People who are in a coma for 12 hours or more will usually have lasting problems with thinking, movement, and sensation. Recovery will often be incomplete and slow, taking weeks to months.
The most severely affected people may end up in a vegetative state, more appropriately known as unresponsive wakefulness syndrome (UWS). The eyes may open in people with UWS, and voluntary movements may occur, but the person does not respond and is unaware of their surroundings.
Restoring the flow of blood through the body is calledreperfusion.It is key to reviving the person and preventing or limiting brain damage.
Reperfusion is necessary, but it has to be done methodically and in a highly controlled way. That’s because the sudden rush of blood to areas of damaged tissues can cause injury.
It may seem counterintuitive because restarting the flow of blood is the critical goal. But the lack of oxygen and nutrients during the time of cardiac arrest means that when blood flow is restored, it placesoxidative stresson the brain as toxins flood already-damaged tissues.
The inflammation and nerve injury this causes can trigger a cascade of symptoms, including:
The severity of these symptoms is closely linked to how long the person went without oxygen. Other factors include any pre-existing conditions affecting the brain and cardiovascular system.
Summary
When the heart stops, so does the flow of blood that’s pumped throughout the body. Brain damage will begin in a matter of minutes because of the lack of oxygen.
Cardiac arrest is usually fatal outside of a hospital setting, but even those who are revived may have severe and lasting impacts. It’s important to act quickly to restart the heart and limit these catastrophic effects.
Every second counts if someone suddenly collapses in front of you and stops breathing. Rather than wasting time putting the victim in the car and rushing to the hospital, call 911 and starthands-only CPRimmediately. You may buy enough time until the paramedics arrive to restart the heart.
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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