Sudden cardiac arrest is a life-threatening medical emergency that can strike without warning. As you learn more about this condition, you may come across some unfamiliar words and phrases. This guide explains some of the key terminology related to sudden cardiac arrest to help you understand this complex topic.
We also have a comprehensive glossary that you can also view and is utilised throughout the website via tooltips (indicated via dots under words).
What is Sudden Cardiac Arrest?
Sudden cardiac arrest (SCA) occurs when the heart unexpectedly stops beating due to an electrical malfunction. This causes an irregular heartbeat and disrupts the heart’s pumping action, preventing blood flow to the brain and other vital organs. SCA leads to loss of consciousness and death within minutes if the victim does not receive treatment.
SCA is not the same as a heart attack, which is caused by a blockage that prevents blood flow to the heart. However, a heart attack can sometimes trigger an SCA. SCA may also be caused by structural heart disease, abnormal heart rhythms, or other factors.
Key Differences
Cardiac Arrest – The broader medical term for when the heart stops beating suddenly. Can occur both in and out of hospital settings.
Sudden Cardiac Arrest – An unexpected cardiac arrest that occurs rapidly, usually within an hour of onset of symptoms, in people with no known health conditions. More widely used in public health awareness.
Out-of-Hospital Cardiac Arrest – A cardiac arrest occurring in the community, at home, work or in public. Distinct from in-hospital cardiac arrests.
Sudden Cardiac Death – An unexpected, natural death from cardiac causes within a short time period, generally ≤1 hour from symptom onset, in someone without known fatal conditions.
Heart Attack – When blood flow to the heart is blocked, usually due to a build-up of plaque in the arteries. The biggest cause of an SCA as it often triggers an arrhtymia if untreated.
Underlying Causes and Mechanisms
Ventricular Fibrillation – When the heart’s lower chambers quiver rapidly and irregularly, causing the pumping function to cease. The most common cause of SCA in adults. Requires defibrillation.
Ventricular Tachycardia – A very fast heart rhythm originating in the lower chambers. Can lead to ventricular fibrillation.
Asystole – When electrical activity in the heart completely stops. No heartbeat detected. Less treatable than ventricular arrhythmias.
Pulseless Electrical Activity – Electrical activity in heart detected, but insufficient to produce a pulse. Requires treatment of underlying cause.
Idiopathic – Term used when the cause of a cardiac arrest is unknown or undetermined after evaluation. This is a relatively rare diagnosis but accounts for roughly one-third of the SCA UK survivors.
Resuscitation and Survival
Chain of Survival – The series of actions that together optimize chances of survival from SCA. Includes early recognition, CPR, defibrillation, and post-arrest care.
Cardiopulmonary Resuscitation (CPR) – Emergency procedure to manually preserve intact brain function until further measures taken. Involves chest compressions and sometimes rescue breaths.
Defibrillation – AKA Shock – Delivery of electric current to stop a fatal arrhythmia and allow the heart to re-establish an effective rhythm and pumping function. This can be actioned externally via an automatic external defibrillator (AED) or if the patient has one, internally via an implantable cardioverter defibrillator (ICD). Read more…
Return of Spontaneous Circulation – The point at which circulation is restored and a palpable pulse returns after cardiac arrest treatment.
Downtime – Duration that a person is in cardiac arrest. Longer downtime associated with worse outcomes.
Agonal Breathing – Abnormal, irregular gasping occurring during cardiac arrest. Indicates the brain is still alive and in need of oxygen.
Post-arrest Care – Ongoing care to stabilise the patient, prevent further damage, and support recovery after achieving return of spontaneous circulation.
In Summary
Learning the specific medical terminology for sudden cardiac arrest can help you grasp the details of this condition. Knowing the key terms enables clearer communication with healthcare providers as you seek information and support. However, the most crucial points for the general public are recognising SCA, calling emergency services immediately, starting CPR, and using an AED if available. Swift action as soon as SCA is identified offers the best chance of survival.