Sudden cardiac arrest
Sudden cardiac arrest is the abrupt cessation of cardiac function with loss of pulse and consciousness, most often from a ventricular tachyarrhythmia on a background of coronary disease. Survival depends on immediate CPR and defibrillation of shockable rhythms, followed by treatment of the cause and secondary prevention with an ICD.
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What this article covers
- Overview
Definition: sudden cardiac arrest is the abrupt cessation of effective cardiac mechanical function, with loss of pulse, breathing, and consciousness; it is fatal without immediate intervention (sudden cardiac death if not reversed).
- Epidemiology
A leading cause of death, with most events out of hospital.
- Risk factors
Coronary artery disease and prior myocardial infarction.
- Pathophysiology
Ventricular tachyarrhythmia: ischemia or scar creates a substrate for ventricular fibrillation or pulseless VT that abolishes cardiac output.
- Clinical features
Sudden collapse, unresponsiveness, and apnea or agonal breathing.
- Differential diagnosis
Ventricular fibrillation: the leading shockable mechanism, chaotic irregular ventricular activity on the monitor, distinguished from asystole and pulseless electrical activity by a shockable…
- Diagnosis
Establish clinically by unresponsiveness, apnea, and pulselessness, then classify the rhythm as shockable or non-shockable: the diagnostic basis is immediate recognition of arrest at the bedside…
- Management
First-line, start high-quality CPR and defibrillate shockable rhythms: begin uninterrupted chest compressions and deliver an immediate unsynchronized shock for ventricular fibrillation or pulseless VT, resuming compressions at once.
- Complications
Death or anoxic brain injury. Post-cardiac-arrest syndrome: myocardial dysfunction and multiorgan injury.
- Prognosis
Poor overall but highly dependent on bystander CPR, early defibrillation, and the initial rhythm (better for shockable rhythms).
- Prevention
ICD for secondary prevention, and for primary prevention when ejection fraction is 35 percent or less despite at least 3 months of guideline-directed therapy.
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Related articles
- Ventricular fibrillation
Ventricular fibrillation is chaotic, disorganized ventricular electrical activity with no effective contraction, producing immediate loss of cardiac output and cardiac arrest. It is the leading shockable arrest rhythm, and survival depends on immediate CPR and defibrillation, followed by treatment of the cause and an ICD for secondary prevention.
- Ventricular tachycardia
Ventricular tachycardia is three or more consecutive ventricular beats at over 100 per minute, a wide-complex tachycardia that is life-threatening when sustained. Any regular wide-complex tachycardia is ventricular tachycardia until proven otherwise: unstable patients are cardioverted or defibrillated, and long-term risk is managed with an implantable defibrillator.
- ST-elevation myocardial infarction (STEMI)
ST-elevation myocardial infarction is acute transmural myocardial ischemia from complete coronary occlusion, diagnosed by ischemic symptoms with diagnostic ST-segment elevation and a rising troponin. It is a time-critical emergency in which immediate reperfusion, primary PCI within 90 minutes or fibrinolysis when PCI is unavailable, plus antiplatelet and anticoagulant therapy, determines survival.
- Syncope
Syncope is a transient loss of consciousness from global cerebral hypoperfusion with spontaneous complete recovery. The central task is separating benign reflex and orthostatic causes from dangerous cardiac syncope, using history, examination, and ECG, since cardiac syncope carries a risk of sudden death; treatment is directed by mechanism, from reassurance and hydration for reflex syncope to a pacemaker, ICD, or structural intervention for cardiac syncope.