The most common shockable rhythms associated with cardiac arrest are pulseless ventricular tachycardia and ventricular fibrillation.
The most common underlying causes are ischaemic heart disease and myocardial infarction. In some settings, cardiac arrest is the result of respiratory arrest triggered by opioid toxicity.
Presentation is usually sudden and manifests as loss of consciousness but can be preceded by chest pain or dyspnoea.
Treatment is through implementing the algorithms for basic and advanced cardiac life support, depending on the provider’s level of training.
The overall survival from cardiac arrest, especially unwitnessed, is poor and, among early survivors, is fraught with complications of many organ systems due to ischaemic injury (i.e., multisystem organ failure).
This topic covers cardiac arrest in adults. Sudden cardiac arrest is a sudden state of circulatory failure due to a loss of cardiac systolic function. It is the result of 4 specific cardiac rhythm disturbances: ventricular fibrillation, pulseless ventricular tachycardia (VT), pulseless electrical activity, and asystole. Torsades de pointes is a sub-group of polymorphic VT in patients with an underlying prolonged QT interval, sometimes related to hypomagnesaemia.
History and exam
Key diagnostic factors
- patient unresponsive
- absence of normal breathing
- absence of circulation
- cardiac rhythm disturbance
- coronary artery disease (CAD)
- left ventricular dysfunction
- hypertrophic cardiomyopathy (HCM)
- arrhythmogenic right ventricular dysplasia (ARVD)
- long QT syndrome (LQTS)
- medications that prolong the QT interval or cause electrolyte disturbances
- acute medical or surgical emergency
- illicit substances
- Brugada syndrome
- valvular heart disease
- history of eating disorders
1st investigations to order
- continuous cardiac monitoring
- serum electrolytes
- cardiac biomarkers
- point of care ultrasound (POCUS)
Investigations to consider
- coronary angiography
- chest x-ray
- toxicology screen
- cardiac magnetic resonance imaging
- signal-averaged electrocardiogram (SAECG)
- electrophysiological study
unwitnessed cardiac arrest
shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)
non-shockable rhythms (pulseless electrical activity or asystole)
return of spontaneous circulation
no return of spontaneous circulation
- Guideline on management of cardiac arrest in the cardiac catheter laboratory
- Opioid-associated out-of-hospital cardiac arrest: distinctive clinical features and implications for health care and public responses: a scientific statement from the AHA
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