Sudden Cardiac Arrest Treatment

Sudden Cardiac Arrest Treatment

SCA Treatment

How To Save a Life
Transfer Care to Medical Professionals
Therapeutic Hypothermia
Post-Resuscitation Care
Wearable Cardioverter Defibrillator
Implantable Cardioverter Defibrillator (ICD) Therapy
Bystander Intervention in Medical Emergencies: What the Research Says

Read about the Chain of Survival here.

How To Save a Life

Sudden cardiac arrest (SCA), often misunderstood as a massive heart attack, is a treatable condition that does not have to lead to sudden death. When someone suffers SCA, he or she may be fine one minute and then collapse without warning the next. Without immediate intervention, the victim almost always dies. SCA is the leading cause of death in the U.S., affecting more people than breast cancer, prostate cancer, colorectal cancer, AIDS, traffic accidents, house fires and gunshot wounds combined. Only 11% survive nationally--but 38% or more could survive.

You can make the difference between life and death for someone you care about by knowing what to do and doing it quickly. SCA victims need immediate help--waiting for emergency personnel to arrive at the scene can lead to delays in care and reduce the chances for survival. That is why you must learn how to act quickly and effectively. Here is how you can save a life:


Learn how to recognize sudden cardiac arrest (SCA). When someone is in SCA, he or she suddenly loses consciousness, normal breathing stops, and there are no signs of life.

  1. Decide to help. Victims of SCA can only be saved if bystanders intervene immediately. There may not be enough time to wait for professional rescuers to arrive at the scene. The chances for survival decrease 10% with each passing minute after collapse. You may be the victim's only hope for survival.
  2. Call 9-1-1 or better yet have someone else nearby to call 9-1-1 to get professional help on the way so you can start treatment. Be sure to communicate with a specific person, such as "Bob, call 9-1-1," otherwise bystanders in a crowd may hesitate and wait for someone else to help.
  3. If an automated external defibrillator (AED) is immediately available, grab it or send someone to retrieve it and bring it to you. Apply the AED electrode pads to the person's chest as shown on diagrams that accompany the AED. Follow the voice and visual prompts. If a person is in a heart rhythm that needs to be shocked, the AED will automatically shock the heart. This electrical therapy can restore a normal heart rhythm if it is used quickly enough. Do not be concerned about harming the victim. AEDs are safe and effective and can only help. AEDs will not shock someone who does not need to be shocked. 9-1-1 medical dispatchers can provide additional guidance.
  4. If an AED is not immediately available and you are trained in cardiopulmonary resuscitation (CPR), push down hard and fast in center of chest (2” depth, 100 pumps/minute) 30 times. Give two breaths. Repeat.
  5. If an AED is not immediately available, and you are not trained in CPR, push down hard and fast in the center of the chest (2” depth, 100 pumps/minute.) Continue. Think “Stayin’ Alive" by the BeeGees

  6. Remember saving victims from sudden death due to SCA depends on immediate bystander intervention. 


It’s important for laypersons to undergo training in CPR and AED use because emergency personnel cannot always get to the victim’s side quickly enough. If you haven't taken a CPR-AED course it's a good idea to spend some time learning these fundamental lifesaving skills.


One of the most common reasons SCA victims do not survive is that bystanders hesitate to call 9-1-1, start CPR and use AEDs right away. If you want to save a life, get involved. Your actions can only help. Doing nothing is the worst option.

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Transfer Care to Medical Professionals

Once emergency medical services personnel arrive at the scene, they will continue defibrillation efforts as needed, provide advanced cardiac life support, and transport the victim to the hospital. Doctors there may provide antiarrthythmia medications (e.g., beta blockers, angiotensin-converting (ACE) inhibitors, calcium channel blockers, amiodarone) and in certain cases use therapeutic hypothermia (cooling to prevent injury to vital organs).

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Therapeutic Hypothermia

Sudden cardiac arrest (SCA) is a devastating event for its victims and their families, with only a small number of survivors. Less than half of the 25 to 50 percent of people whose hearts can be started again survive to leave the hospital because prolonged time without blood flow to the brain often leads to irreversible brain damage.

Medical researchers have placed significant emphasis on increasing SCA survival by reducing brain injury. One relatively new, promising treatment is the use of therapeutic hypothermia for comatose survivors of cardiac arrest. Physicians have known for years that brain injury can sometimes be prevented by decreasing a patient’s core body temperature. Cardiac surgeons, for example, have used hypothermia during open heart surgical procedures to reduce the body’s metabolism and to minimize damage to vital organs during prolonged periods of little or no blood flow.

The potential benefit of using hypothermia for treating cardiac arrest patients was suggested by reports of occasional drowning victims surviving with minimal brain injury after up to 45 minutes submerged under icy water. Hypothermia slows the body’s metabolism, reducing the cascade of undesirable events that can cause permanent brain damage associated with SCA. The reason that cooling is helpful for some patients is that once the patient is resuscitated and circulation resumes, reperfusion to vital organs occurs. This sets in motion the production of free radicals, which can lead to cell damage or death. Scientists believe that mild therapeutic hypothermia suppresses these chemical reactions and preserves cell health.

Since the mid-1950s, researchers have studied the effects of this cooling therapy in models of animals that survived cardiac arrest, reporting varying degrees of success. Cooling was achieved using ice packs, water blankets, cold air, and other methods. In 2002, the New England Journal of Medicine reported two successful clinical research studies in which patients who survived SCA were cooled to subnormal temperatures of about 91.4°F (33°C). The patient survival rate in each study increased, and the improvement in neurological outcomes was significantly better than among patients in the group who maintained normal temperatures.

As a result of this work and subsequent studies verifying these findings, the American Heart Association in 2003 and again in 2005 issued guidelines recommending cooling comatose survivors of cardiac arrest caused by certain irregular heart rhythms known as ventricular tachycardia (VT) and ventricular fibrillation (VF). Although therapeutic hypothermia will not work for every SCA patient treated, the good news is that this treatment offers more hope for improving brain function than in the past. Physicians believe, although the evidence is not strong, that the earlier the treatment is started the more effective it will be.

The main risks of using hypothermia are infection and bleeding. Decreasing the body’s temperature slows down white blood cells that fight infection and also slows down the processes for developing a blood clot.

If you know someone who has remained comatose after surviving SCA, he may be a candidate for therapeutic hypothermia. Check with the physicians who are caring for the patient to see if the hospital is currently using this therapy and if your family member meets the criteria to be cooled. The therapy is not without risk and requires skilled implementation of techniques for managing the critically ill patients whose body temperatures have been lowered. Members of the critical care team must learn these techniques before using them clinically. Techniques can include ice packs, cooling mattresses, cooling blankets, catheters inserted into large blood vessels, and ice-cold IV saline.

When a patient undergoes therapeutic hypothermia, it is somewhat startling to feel how cold s/he can be to the touch. This is normal and is only temporary. The patient’s temperature will be reduced to about 91°F (33°C), approximately 7° F (4°C) lower than normal.

The patient will be on a respirator, heavily sedated and unable to move. The therapy typically will last for a maximum of 36 hours: 12 to 24 hours of cooling and up to 12 hours to rewarm slowly back to a normal body temperature of 98.6° (37°C).

During the cooling process, the patient will require frequent blood samples to make sure s/he is tolerating the cooling procedure well. Sometimes, additional medications can be given to help control blood pressure and heart rate.

If your family member or friend is treated with therapeutic hypothermia, you will not know anything about his/her level of consciousness until the therapy is terminated. Sometimes, it can take days before the doctor knows whether the therapy is successful.

Always discuss your concerns with the nurses and physicians taking care of your family member.

Key Research Studies

Two prospective randomized trials (see below) compared mild hypothermia (32-34 degrees Celcius with normothermia in comatose SCA survivors. The first, conducted in five Eurpean countries, demonstrated that cooling for 24 hours decreased the likelihood of death and increased the likelihood of good neurological recovery. The second, conducted in four hospitals in Melbourne, Australia, showed that cooling patients for 12 hours increased the chances for good neurological recovery.

Mild hypothermia to improve the neurologic outcome after cardiac arrest: The Hypothermia After Cardiac Arrest Group (HACA). N Engl J Med. 2002;346:549-556.

In a randomized trial of 273 survivors of sudden cardiac arrest, 75 of 136 patients (55%) treated with hypothermia had a favorable neurologic outcome as compared with 54 of 137 patients (39%) who maintained normothermia. Mortality in the hypothermia group was 41% compared with 55% in the normothermia group.

Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. Bernard SA, Gray TW, Buist MD, et al. NEJM 2002; 346:557-63.

Of the 77 survivors of sudden cardiac arrest who were randomized, 43 patients treated in the hypothermia group (49%) survived with a good outcome compared to 34 (26%) in the normothermia group.

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Post-Resuscitation Care

Once the patient’s condition stabilizes, the following therapies may be considered:

  • Wearable cardioverter defibrillator
  • Implantable cardioverter-defibrillator (ICD) therapy
  • Coronary angioplasty
  • Coronary bypass surgery
  • Radiofrequency catheter ablation
  • Corrective heart surgery
  • Heart transplantation

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Wearable Cardioverter Defibrillator

Life VestThe Wearable Cardioverter Defibrillator (WCD) is a device that is worn by patients at risk for sudden cardiac arrest (SCA), providing protection during their changing condition and while permanent SCA risk has not been established. The WCD allows a patient’s physician time to assess their long-term arrhythmic risk and make appropriate plans. The WCD does not require bystander intervention and has a 98 percent first treatment shock success rate for resuscitating patients from SCA.1,2,3

The WCD is lightweight and easy to wear, allowing patients to return to their activities of daily living, while having the peace of mind that they are protected from SCA. The WCD is non-invasive and consists of two main components – a garment and a monitor. The garment, worn under the clothing, detects arrhythmias and delivers treatment shocks. The monitor is worn around the waist or from a shoulder strap and continuously monitors the patient’s heart.

If a life-threatening heart rhythm is detected, the device delivers a treatment shock to restore normal heart rhythm. The entire event, from detecting a life-threatening arrhythmia to automatically delivering a treatment shock, usually occurs in less than a minute. Timely defibrillation is the single most important factor in saving a SCA victim’s life. A treatment shock must be delivered within a few minutes after an event to be effective; with each passing minute, a patient’s chances of survival drops 10 percent.

The WCD is prescribed by a physician as part of the continuum of care for patients at risk for SCA. It is used for a wide range of patient conditions or situations, including following a heart attack, before or after bypass surgery or stent placement, as well as for those with cardiomyopathy or congestive heart failure that places them at particular risk for SCA. The WCD is covered by most health plans in the United States, including commercial, state, and federal plans.

1Chung M et al. Aggregate national experience with the wearable cardioverter-defibrillator: Event rates, compliance and survival. J Am Coll Cardiol 2010;56:194–203.

2 Klein HU, Meltendorf U, Reek S, et al. Bridging a temporary high risk of sudden arrhythmic death: Experience with the wearable cardioverter defibrillator (WCD). Pacing Clin Electrophysiol. 2010;33:353-367.

3 Kutyifa V, Moss AJ, Klein H, et al. Use of the wearable cardioverter defibrillator in high-risk cardiac patients: Data from the prospective registry of patients using the wearable cardioverter defibrillator (WEARIT-II Registry). Circulation 2015;132(17):1613-1619.

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Implantable Cardioverter Defibrillator (ICD) Therapy


Definite high risk
Individuals considered at definite high risk for sudden cardiac arrest (SCA) who should be evaluated by an electrophysiologist (EP) to determine if implantable cardioverter defibrillator (ICD) therapy is warranted include:

  • SCA survivors
  • People who have sustained ventricular tachycardia (VT), a condition in which the heartbeat suddenly speeds up to dangerous levels
  • People who have a familial or genetic condition that puts them at high risk for sustained VT, such as long QT syndrome or hypertrophic cardiomyopathy.

Possible high risk
Individuals who may be at possible high risk for SCA who should be evaluated by a cardiologist to ascertain the need for further evaluation by an EP to determine if ICD therapy is warranted include:

  • People who have survived a heart attack (myocardial infarction) and who have impaired pumping function
  • People with congestive heart failure (CHF), due to either coronary artery disease or cardiomyopathy
  • People who have experienced palpitations, fainting spells, frequent episodes of dizziness, or known episodes of cardiac arrhythmia (abnormal heartbeat)
  • People with an immediate family member (blood relative) who has experienced SCA.

The Device and How it Works

An implantable cardioverter defibrillator (ICD) is a small, computerized device that is implanted in the upper chest of patients who are at risk for sudden cardiac arrest (SCA). Most ICDs can fit easily in the palm of the hand. The ICD detects abnormal heart rhythms, delivers electrical energy to the heart muscle, and restores a normal heartbeat.

While pacemakers are designed to speed up a slow heart rate, ICDs are designed to slow down a fast heart beat. Some ICDs also have built-in pacemakers and can address both problems. The ICD has two parts: the lead(s), which monitor the heart rhythm and deliver energy, and the generator which houses a battery and small computer. Energy is stored in the battery until it is needed. When it is not needed, the ICD simply monitors the heart rhythm.

ICDs are programmed to address the specific needs of each patient. They may be programmed to address or more of the following problems to restore a normal heartbeat:

  • Anti-tachycardia pacing (ATP): Delivery of small electrical impulses for when the heart is beating too fast
  • Cardioversion: Delivery of a low energy shock
  • Defibrillation: Delivery of a high energy shock for when the heart is beating dangerously fast
  • Bradycardia pacing: Delivery of small electrical impulses for when the heart is beating too slowly.

Patient Notes

The patient may or may not be aware when the ICD detects an abnormal rhythm and restores a normal rhythm. Patients usually do not feel small impulses. However, cardioversion may feel like a thump on the chest. Defibrillation may feel like a kick in the chest--or the patient may become unconscious and not feel the shock. If a shock is delivered the patient should:

  1. Sit or lie down
  2. Call 9-1-1 if he or she does not feel well
  3. Call the doctor within 24 hours if he or she does feel well.

Patients with ICDs should visit their electrophysiologist (EP) or cardiologist once a year to see whether any programming adjustments are needed.

Video - The Use of ICDs

“The Role of Implantable Defibrillators in Preventing Death from Cardiac Arrest”
with Dr. Chris Simpson, Kingston General Hospital, Ontario"

NOTE: The Sudden Cardiac Arrest Foundation receives funding from multiple resuscitation companies, including manufacturers of AEDs, wearable defibrillators and ICDs.

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Bystander Intervention in Medical Emergencies: What the Research Says

Research suggests that bystander action in medical emergencies is complex. Key factors affecting bystander action are described below.

Factors that decrease likelihood of bystander intervention

  • Public location of arrest: Compared to healthcare professionals, laypersons are significantly less likely to offer help in emergencies that occur in public places.
  • Ignorance and confusion: When people do not understand what is happening or are confused about the unfolding situation, they are less likely to intervene.
  • Difficulty in recognizing medical emergencies: It is difficult to perceive that a medical emergency is occurring because indications often are ambiguous. Consequently, bystanders often delay in deciding to call EMS for help.
  • Lack of confidence and competence: A person who does not feel competent to deal with an emergency is unlikely to offer even minimal help. CPR is difficult to learn and CPR skill retention is poor when these skills are not used regularly.
  • Presence of other bystanders: The presence of others leads to a diminished sense of personal responsibility.
  • Unpleasant physical characteristics: Regurgitation, blood, dentures and other characteristics of the victim encountered during rescue breathing tend to dissuade bystanders from intervening.
  • Fear of harming the patient: A lack of knowledge and skills inhibit CPR use among families of high-risk patients.
  • Fear of using AEDs incorrectly: People unfamiliar with AEDs tend to be fearful of using them incorrectly.

Factors that increase likelihood of bystander intervention

  • Size of the community in which the bystander lives or grew up: Individuals who grew up in rural areas are more likely to help than individuals from urban areas. People from non-metropolitan areas are more likely to help than their counterparts.
  • Presence at the time of the event: Bystanders who witness the emergency are more likely to help than those who arrive after the emergency has occurred.
  • Previous emergency training and positions of responsibility: People with CPR training or other emergency training and people with positions of responsibility in their organizations are more likely to help in SCA.
  • Availability of AED: When AEDs are available, bystanders are more likely to initiate CPR.

Inconsistencies in the research

  • Fear of disease transmission: Some research indicates bystanders are concerned about contracting infectious disease such as Hepatitis B virus and AIDS. Other research, however, has found fear of disease transmission is not a deterrent to bystander intervention.
  • Fears of liability risks: Some research suggests fear of liability risks are barriers to intervening in SCA. Other research indicates such fears have no bearing on willingness to help.
  • Emotional stress: Studies among healthcare professionals suggest unsuccessful resuscitation efforts can lead to emotional stress. Research among laypersons, however, suggests that levels of stress among laypersons who intervene during SCA are relatively low, due to a sense of altruism and reported psychological “resilience.”

-Mary Newman

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Mission & Vision

The mission of the Sudden Cardiac Arrest (SCA) Foundation is to prevent death and disability from sudden cardiac arrest. The vision of the SCA Foundation is to increase awareness about sudden cardiac arrest and influence attitudinal and behavioral changes that will reduce mortality and morbidity from SCA.

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