In medicine, asystole ( /əˈsɪstəliː/), colloquially known as flatline, is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow. Asystole is one of the conditions that may be used for a medical practitioner to certify clinical or legal death.
Asystole is treated by cardiopulmonary resuscitation (CPR) combined with an intravenous vasopressor such as epinephrine (adrenaline). Sometimes an underlying reversible cause can be detected and treated (the so-called 'H's and T's', an example of which is hypokalaemia). Several interventions previously recommended - such as intravenous atropine and defibrillation - are no longer part of the routine protocols recommended by most major international bodies.
Survival rates in a cardiac arrest patient with asystole are much lower than a patient with a rhythm amenable to defibrillation. Out of hospital survival rates (even with emergency intervention) are less than 2 percent.
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