cardiac arrest

cardiac arrest
Name	Cardiac arrest
Field	Cardiology, Emergency medicine
Symptoms	Loss of consciousness; absence of pulse; cessation of breathing
Complications	Sudden cardiac death, Brain ischemia, Hypoxic brain injury
Onset	Sudden
Duration	Depends on resuscitation
Causes	Myocardial infarction, Cardiomyopathy, Electrolyte imbalance
Diagnosis	Clinical assessment; Electrocardiography
Treatment	Cardiopulmonary resuscitation, Defibrillation, Advanced cardiac life support
Medication	Epinephrine (drug), Amiodarone
Prognosis	Variable; influenced by time to return of spontaneous circulation

cardiac arrest is the abrupt cessation of effective cardiac mechanical activity leading to loss of systemic perfusion and consciousness. It is a true medical emergency requiring immediate recognition and intervention to prevent irreversible Hypoxic brain injury and Sudden cardiac death. Incidence varies by setting, with high rates in out‑of‑hospital and in‑hospital contexts that intersect with Emergency medical services and hospital systems such as American Heart Association guidelines.

Signs and symptoms

Presentation is usually dramatic and sudden: collapse, unresponsiveness, absent normal breathing, and no palpable central pulse. Observers often describe fixed, dilated pupils and pallor; agonal respirations or gasping can mimic breathing. Early recognition relies on bystanders, including personnel trained via programs from Red Cross (disambiguation), European Resuscitation Council, and local hospital Emergency department teams. In monitored settings such as Cardiac catheterization laboratory or Intensive care unit the first sign may be an abrupt change on Electrocardiography, including ventricular tachyarrhythmias.

Causes and risk factors

Common precipitants include acute coronary events such as Myocardial infarction and structural disorders like Hypertrophic cardiomyopathy or dilated Cardiomyopathy. Primary electrical disorders—examples include Long QT syndrome and Brugada syndrome—increase arrhythmic risk. Noncardiac contributors include severe hypoxia from Chronic obstructive pulmonary disease exacerbations or drowning, major metabolic disturbances (e.g., hyperkalemia from Chronic kidney disease), and drug toxicity such as overdose on Tricyclic antidepressants or illicit stimulants like Cocaine. Demographic and clinical risk factors are described in epidemiologic studies from organizations like World Health Organization, Centers for Disease Control and Prevention, and national registries linking age, prior Coronary artery disease, and comorbidities to higher incidence.

Pathophysiology

Failure of coordinated myocardial contraction results from either a lethal arrhythmia—ventricular fibrillation, pulseless ventricular tachycardia—or from asystole and pulseless electrical activity. In ischemic causes, acute occlusion of a coronary artery (e.g., lesions identified in Percutaneous coronary intervention) triggers electrical instability via ischemia‑reperfusion injury, altered ion channel function, and heterogeneity of repolarization. Structural abnormalities from inherited disorders such as Arrhythmogenic right ventricular cardiomyopathy create scar and conduction block, promoting reentry circuits. Systemic insults—hypoxia, acidosis, electrolyte derangements—disrupt myocardial membrane potentials and impair excitation–contraction coupling, while prolonged ischemia leads to irreversible cellular injury and activation of apoptotic pathways documented in translational work from institutions like National Institutes of Health.

Diagnosis

Diagnosis is immediate and clinical: unresponsiveness, apnea or abnormal respiration, and absent carotid pulse assessed by trained rescuers. In monitored patients, bedside Electrocardiography confirms arrhythmia type; portable defibrillators provide rhythm analysis used by Paramedics and in hospital code teams. Point‑of‑care testing—arterial blood gas, electrolytes, and bedside ultrasound performed in Emergency department or Intensive care unit—identifies reversible causes such as pericardial tamponade or tension pneumothorax. Post‑resuscitation care includes targeted temperature management guided by protocols from professional societies and advanced imaging (e.g., Coronary angiography) when ischemia is suspected.

Treatment and management

Immediate chain‑of‑survival steps prioritize high‑quality Cardiopulmonary resuscitation with minimal interruptions, early recognition and activation of Emergency medical services, and rapid defibrillation for shockable rhythms using automated external defibrillators found in public spaces promoted by programs like Public access defibrillation. Advanced cardiac life support algorithms from the American Heart Association and European Resuscitation Council recommend airway management, vascular access, administration of Epinephrine (drug) and antiarrhythmics such as Amiodarone for refractory arrhythmias, and treatment of reversible causes summarized as the Hs and Ts. In survivors, postarrest care includes hemodynamic optimization, neuroprotection strategies, targeted temperature management, and consideration of coronary reperfusion via Percutaneous coronary intervention when appropriate. Implantable cardioverter‑defibrillators are indicated in selected patients meeting criteria from guideline bodies like Heart Rhythm Society.

Prevention and prognosis

Primary prevention targets underlying disease: risk factor modification for Coronary artery disease through interventions supported by World Health Organization and national programs, screening in families with inherited disorders via genetic clinics, and secondary prevention with devices such as implantable cardioverter‑defibrillators. Public health measures—widespread cardiopulmonary resuscitation training promoted by Red Cross (disambiguation), placement of automated external defibrillators, and integration of dispatch‑assisted CPR—improve survival in out‑of‑hospital events. Prognosis depends on time to return of spontaneous circulation, initial rhythm, witness status, and quality of resuscitation; neurologic outcome correlates with duration of cerebral hypoperfusion and effectiveness of postarrest care studied by centers like National Institutes of Health and major academic hospitals. Long‑term outcomes range from full recovery to significant neurologic impairment or death, with morbidity patterns reported in cohort studies across United States, United Kingdom, and international registries.

Category:Cardiology