Asystole
Asystole is the absence of heart contractions in lethal cardiac arrest.
Asystole, from New Latin and Greek meaning 'without contraction,' is the absence of ventricular contractions in the context of a lethal heart arrhythmia. It is the most serious form of cardiac arrest, usually irreversible, and is also referred to as cardiac flatline, representing total cessation of electrical activity from the heart.
- definition
- Absence of ventricular contractions in lethal heart arrhythmia
- also known as
- Cardiac flatline
- prognosis
- Usually irreversible; out-of-hospital survival less than 2%
- initial occurrence
- Found in about 28% of hospitalized cardiac arrest cases
- survival rate
- 15% in hospitalized patients; 6% for those on blood pressure drugs
- treatment
- CPR and intravenous epinephrine (1 mg every 3-5 minutes)
- reversible causes
- Hs and Ts (e.g., hypovolemia, hypoxia, hypothermia, toxins)
Lore & Background
Asystole is the state of total cessation of electrical activity from the heart, meaning no tissue contraction and no blood flow to the body. It should not be confused with brief pauses under 3 seconds in heart electrical activity, nor with very fine ventricular fibrillation, though both have poor prognosis and untreated fine VF can lead to asystole. Faulty wiring, disconnection of electrodes, and power disruptions must be ruled out before diagnosis.
Reader's Guide
Asystole represents the most serious form of cardiac arrest and is usually irreversible. It is found initially in about 28% of hospitalized cardiac arrest cases, with only 15% surviving even in intensive care, and a lower 6% survival for those on blood pressure drugs. Out-of-hospital survival rates are less than 2%. Treatment involves CPR and intravenous epinephrine every 3-5 minutes, with defibrillation and atropine no longer routinely recommended. Even if asystole converts to a shockable rhythm, survival to discharge does not necessarily improve. After 15 minutes of asystole, severe hypoxic brain damage is likely, leading to brain death or persistent vegetative state.
Did You Know?
- Asystole is found initially in only about 28% of cardiac arrest cases in hospitalized patients.
- Out-of-hospital survival rates for asystole are less than 2 percent.
- Defibrillation is known to be ineffective on asystole and is no longer part of routine protocols.
- If asystole persists for fifteen minutes or more, severe hypoxic brain damage is expected.
Frequently Asked Questions
What exactly is asystole in medical terms?
Asystole refers to a complete lack of ventricular contractions during a life-threatening heart rhythm disturbance. It represents the most severe category of cardiac arrest, where the heart's electrical system has shut down entirely.
What is the common nickname for asystole?
In everyday clinical language, asystole is widely called a "cardiac flatline" because the ECG trace shows a straight, motionless line. This term captures the total absence of any electrical signal coming from the heart.
How often does asystole show up in hospital cardiac arrest cases?
Among patients who suffer a cardiac arrest while already hospitalized, asystole is the initial rhythm in roughly 28 percent of those cases. It is therefore one of the most frequently encountered arrest rhythms in an inpatient setting.
What are the realistic survival chances for someone in asystole?
Out-of-hospital survival drops below 2 percent, making it one of the least survivable arrest rhythms. In a hospital setting the figure improves to about 15 percent, though it falls to roughly 6 percent for patients who were on blood-pressure medications.
What is the standard treatment protocol for asystole?
The immediate response is high-quality CPR combined with intravenous epinephrine, given as a 1 mg bolus every three to five minutes. Despite these interventions, the condition is generally considered irreversible once established.
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