Asystole

Asystole
Other names: Cardiac flatline, asystolic arrest
A rhythm strip showing two beats of normal sinus rhythm followed by an atrial beat and asystole
Pronunciation	/əˈsɪstəliː/
Symptoms	Unresponsive, no pulse[1]
Complications	Brain damage[2]
Causes	Hs and Ts: hypoxia, hyperkalemia, hypovolemia, hypothermia, cardiac thrombosis, pulmonary thrombosis, tamponade, tension pneumothorax, toxins[3]
Diagnostic method	ECG showing a more or less flat line[3][4]
Differential diagnosis	Fine ventricular fibrillation, PEA[1][2]
Treatment	CPR, epinephrine[5]
Prognosis	Very poor[3]
Deaths	>98% risk of death[3]

Asystole is when there is neither movement nor electrical activity from the ventricle of the heart.^[2] The person is unresponsive, not breathing properly, and without a pulse.^[1][6] Gasping breaths may be present.^[2] It is the type of cardiac arrest with the worst outcomes, and is usually irreversible.^[3] Among those who survive, brain damage may have occurred.^[2]

Causes include the Hs and Ts: hypoxia, hyperkalemia, hypovolemia, hypothermia, cardiac thrombosis, pulmonary thrombosis, tamponade, tension pneumothorax, and toxins.^[3] It often occurs after a period of pulseless electrical activity or ventricular fibrillation.^[6] The underlying mechanism results in no cardiac output.^[3] Diagnosis is by an ECG showing a more or less flat line which may wonder a bit.^[3][4] In a different context, some have defined it as a sinus pause greater than 3 seconds, but this may be better termed sinus arrest.^[7][8] The monitor connections should be checked and the rhythm verified in multiple leads.^[2][4]

Treatment is with cardiopulmonary resuscitation (CPR) and epinephrine.^[5] Epinephrine is generally given as early as possible at a dose of 1 mg intravenously every 3–5 minutes.^[9][2] Shocking the person, pacing, and atropine are not generally useful.^[3][10][6] Evidence dose not support the use of a precordial thump.^[6] Prolonged resuscitation efforts are rarely indicated.^[1]

Asystole is found initially in about half of out-of-hospital cardiac arrests and 28% of among hospitalized people.^[11][1][12] Survival in out-of-hospital cases is less than 2% and in-hospital cases is about 10%.^[3] Good neurological outcomes occurred in less than 1% of people.^[11] It is New Latin, from Greek privative a meaning "not, without" and systolē meaning "contraction".^[13][14]

Cause

Possible underlying causes, which may be treatable and reversible in certain cases, include the Hs and Ts.^[15][16][17]

• Hypovolemia
• Hypoxia
• Hydrogen ions (acidosis)
• Hypothermia
• Hyperkalemia or hypokalemia
• Toxins (e.g. drug overdose)
• Cardiac tamponade
• Tension pneumothorax
• Thrombosis (myocardial infarction or pulmonary embolism)

While the heart is asystolic, there is no blood flow to the brain unless CPR or internal cardiac massage (when the chest is opened and the heart is manually compressed) is performed, and even then it is a small amount. After many emergency treatments have been applied but the heart is still unresponsive, it is time to consider pronouncing the patient dead. Even in the rare case that a rhythm reappears, if asystole has persisted for fifteen minutes or more, the brain will have been deprived of oxygen long enough to cause severe hypoxic brain damage, resulting in brain death or persistent vegetative state.^[18]

• 
  ECG lead showing asystole (flatline)
• 
  Asystole
• 
  Ventricular fibrillation

See also

• Agonal heart rhythm
• Ictal asystole

References

External links