Cardiac ArrestEdit

Cardiac arrest is a life-threatening medical emergency characterized by the abrupt loss of heart function, consciousness, and the ability to breathe. In many cases, the heart’s rhythm becomes chaotic (often due to ventricular fibrillation or pulseless ventricular tachycardia) and fails to pump blood to the brain and other vital organs. It is distinct from a heart attack, which is typically caused by a blockage in blood flow to the heart muscle and may, in some cases, precipitate a cardiac arrest. For a broader explanation of the physiological mechanisms, see cardiac arrest and ventricular fibrillation.

In the prehospital setting, the majority of cardiac arrests are caused by electrical disturbances that produce no effective cardiac output. If treated promptly, many patients can recover with preserved neurological function. The chance of survival drops by a factor of roughly 7–10% for each minute without intervention, underscoring the importance of rapid action by bystanders and emergency workers. The pathways to survival are often described as the “chain of survival,” which includes immediate recognition, early bystander CPR, rapid defibrillation with a defibrillator or automated external defibrillator, advanced life support by emergency medical services, and post-resuscitation care in a hospital.

Overview

Cardiac arrest can occur suddenly in a person with no prior symptoms or as the dramatic culmination of a chronic cardiovascular disease. The most common presenting rhythm is ventricular fibrillation, in which the heart quivers instead of contracting, preventing effective blood flow. If not corrected quickly, brain injury and death follow within minutes. The body’s recovery after resuscitation depends on how quickly circulation and oxygen delivery are restored and how well the brain is protected during the interval of low blood flow. See cardiopulmonary resuscitation for the foundational technique used to maintain circulation in the field, and see therapeutic hypothermia or targeted temperature management for strategies used after return of spontaneous circulation in some patients.

Causes and risk factors

Cardiac causes: The most common underlying problem is disease of the coronary arteries, which can lead to myocardial infarction and, in turn, to lethal arrhythmias. Other cardiac conditions include arrhythmias such as ventricular tachycardia and familial or acquired cardiomyopathies. See myocardial infarction and cardiomyopathy for related material.
Non-cardiac and provoking events: Drowning, severe trauma, drug overdose, severe electrolyte disturbances, and respiratory arrest can precipitate cardiac arrest. See asphyxia and electrolyte imbalance for related topics.
Risk factors: Age, smoking, hypertension, diabetes, obesity, a family history of early heart disease, physical inactivity, and prior cardiovascular events increase risk. Socioeconomic and access-to-care factors can influence both risk and outcomes, including differences in access to timely bystander intervention and hospital resources. See risk factors for broader context.
Race, geography, and disparities: In some communities, bystander response rates and access to defibrillation can vary, with outcomes influenced by neighborhood resources, training, and emergency response infrastructure. In discussions of public health, these disparities are often cited, though the solutions proposed vary by policy approach. See health disparities for related analyses.

Recognition and immediate response

Recognition: A collapsed person who is not responsive and not breathing normally requires immediate assistance. Early activation of emergency medical services and rapid initiation of bystander intervention are crucial.
Bystander CPR: Performing chest compressions maintains blood flow to vital organs until defibrillation or advanced care can be provided. Training and confidence to act are key bottlenecks in some communities, leading to debates about how best to promote widespread, voluntary skills without coercive mandates. See cardiopulmonary resuscitation.
Defibrillation: A shock delivered by a defibrillator terminates many malignant heart rhythms, restoring a viable rhythm in a substantial minority of out-of-hospital cases. The availability of AEDs in public spaces, workplaces, and schools is a frequent policy focus, with supporters arguing it saves lives and critics warning about costs and maintenance. See automated external defibrillator and defibrillation.

Diagnosis and treatment

In the field: If a shockable rhythm is detected, immediate defibrillation is recommended, followed by high-quality CPR. The effectiveness of bystander interventions is strongly linked to the time between collapse and defibrillation.
In-hospital care: Once stabilized, patients may undergo coronary angiography if a heart attack is suspected and may receive medications to support circulation, manage arrhythmias, and prevent further injury. Post-resuscitation care may include therapeutic hypothermia or targeted temperature management in selected cases to protect the brain. See in-hospital cardiac arrest for related material.
Long-term considerations: Rehabilitation, risk-factor modification, and secondary prevention (such as management of heart disease and lifestyle changes) are central to reducing recurrence. See secondary prevention and cardiovascular disease for broader context.

Prevention and public health considerations

Preventive strategies: Reducing risk factors through lifestyle choices (notably, non-smoking, healthy diet, regular physical activity) and treating underlying heart disease can lower the incidence of cardiac arrest. Medical guidelines emphasize managing hypertension, hyperlipidemia, diabetes, and obesity where possible. See prevention and lifestyle medicine for related topics.
Public access to defibrillators: Public policy debates center on whether to mandate or subsidize AEDs in public venues and workplaces, and how to fund training programs. Proponents argue that time is brain when a life is at stake; critics caution about costs and the potential for misuse or maintenance challenges. See public health and emergency medical services.
Policy perspectives: From a practical, market-minded viewpoint, encouraging voluntary investment in AEDs, training, and EMS capabilities can yield cost-effective gains in survival, while avoiding heavy-handed mandates that could burden schools, small businesses, or local governments. Advocates point to private-sector innovation, philanthropy, and targeted subsidies as efficient ways to expand access.

Controversies and debates

Government role versus private initiative: Debates concern how much public funding and regulation are appropriate to ensure rapid response, training, and equipment versus relying on private organizations, employers, and individuals to fund and manage readiness. A common argument is that private and local solutions can be more flexible and innovative, while still preserving universal access through public emergency services.
Bystander training mandates: Some policymakers push for mandatory CPR training in schools or workplaces, arguing it increases the odds that a collapse will be treated immediately. Critics claim such mandates could create compliance burdens or unintended consequences, and they advocate for voluntary programs with strong incentives and public awareness campaigns.
Equity and access: While improving survival rates is a shared goal, strategies to reduce disparities must balance resource allocation with practical outcomes. Critics from certain policy perspectives emphasize structural reforms in health care to address broader inequities, while proponents focus on targeted investments in community programs, employer-based initiatives, and private philanthropy.
Evidence and evolving guidelines: Medical guidelines for resuscitation and post-arrest care continue to evolve with research. A pragmatic stance emphasizes adherence to proven, high-quality procedures while supporting ongoing innovation in devices, drugs, and systems of care. See clinical guidelines and evidence-based medicine for related discussions.