cardiac arrest
Meaning of cardiac arrest: Not a plumbing problem but an electrical one: the pump stops, the person drops, and everything downstream of circulation halts at once.
Definition of cardiac arrest
Cardiac arrest is the sudden loss of effective pumping by the heart, so blood stops circulating. The usual cause is a chaotic or absent electrical rhythm rather than a blocked artery, although a blockage can set it off. Within seconds the person collapses, loses consciousness and stops breathing normally, and no pulse can be felt. Without circulation the brain and other organs are injured within minutes.
How is it different from a heart attack?
| Feature | Cardiac arrest | Heart attack |
|---|---|---|
| Basic fault | Electrical, and the pump stops | Plumbing, and an artery is blocked |
| The person | Collapsed, unresponsive, no pulse | Usually awake and talking |
| Onset | Instant | Minutes to hours of symptoms |
| Relationship | Can be triggered by a heart attack | Usually does not stop the heart |
The two phrases are swapped freely in ordinary speech and they name different events. A heart attack starves muscle while circulation carries on. Cardiac arrest is the end of circulation itself, and it can follow a heart attack, a dangerous rhythm in a scarred or thickened heart, a severe disturbance of blood salts, drowning, a drug overdose, or a blow to the chest landing at one particular instant of the cycle.
What rhythms lie behind it?
Two broad groups, and the distinction decides whether an electric shock can help. In ventricular fibrillation the pumping chambers quiver instead of contracting, and in pulseless ventricular tachycardia they fire far too fast to fill. Both are disorganized rhythms that a defibrillator can interrupt, giving the heart's own pacemaker tissue a chance to restart in order. The second group covers a flat tracing with no electrical activity at all, and electrical activity that continues while the muscle fails to move any blood. Neither responds to a shock, and treatment there turns on chest compressions and on finding a reversible cause.
How is it recognized?
By two findings: no response, and no normal breathing. Both are less obvious than expected. Noisy, irregular gasping is common in the first minutes and is regularly mistaken for breathing, although it is a sign of arrest rather than evidence against it. Brief stiffening or jerking at the moment of collapse is also common and is often taken for a fit. Injury to the brain begins within minutes, so the interval before circulation is restored is closely tied to the outcome. An ICD, an implanted defibrillator, delivers a shock automatically in people known to be at high risk, which is what separates it from a cardiac pacemaker, a device that paces a slow rhythm and cannot stop a chaotic one. Brain damage from the period without blood flow appears afterward as encephalopathy.
Also known as
Used in a sentence
Cardiac arrest occurred on the ward and a resuscitation call was placed.
Good to know
Cardiac arrest and heart attack are different events: a heart attack is a blocked artery starving muscle, usually in a person who is awake, while cardiac arrest is the loss of circulation itself, and the noisy gasping common in its first minutes is a sign of arrest rather than of breathing.
Word origin
Where “cardiac arrest” comes from
Cardiac comes from the Greek kardia, meaning heart.