ECG rhythms Ventricular and arrest rhythms
Asystole ECG
Asystole. A flat line in two leads, with no P waves and no QRS complexes, in a pulseless patient.
A 30-second recording of the heart model, played in real time. Run live starts the engine itself with this rhythm.
Computed by the TracingsMD heart model (Junkers engine): simulated for education, not a patient recording and not for diagnosis.
Measured on this recording
No QRS complexes: rate and intervals cannot be measured in this rhythm.
What it is
No ventricular electrical activity: a flat line with no QRS complexes (when P waves continue without QRS complexes it is called ventricular standstill or P-wave asystole; this strip has none). There is no cardiac output.
How to read this strip
| Rate | None. |
|---|---|
| Rhythm | None; flat line. |
| P waves | None. |
| PR | None. |
| QRS | None. |
| QT | None. |
Causes
- The end stage of untreated VF or PEA.
- Severe hypoxia, acidosis, hyperkalemia.
- Massive pulmonary embolism, hypothermia, drug overdose.
- Complete heart block without an escape rhythm; extreme vagal tone.
What to consider
- Before calling it asystole, confirm the flat line in a second lead at a higher gain.
- Asystole is not shockable: start CPR and give epinephrine as soon as possible. Transcutaneous pacing is not recommended for asystolic cardiac arrest.
- Search for the reversible causes (the Hs and Ts: hypoxia, hypovolemia, hydrogen ion excess, hypo- or hyperkalemia, hypothermia, tension pneumothorax, tamponade, toxins, thrombosis).
- The outlook is poor: consider goals of care and local guidance on ending resuscitation.
Key point
Confirm a flat line in a second lead and check leads and gain, but keep the pause short: very fine VF and a loose lead can both look flat.
Not to be confused with
- Fine ventricular fibrillation — Fine VF still shows small chaotic waves. Both leads here show only a nearly flat, slowly drifting baseline.
- Pulseless electrical activity — PEA needs organized complexes on the monitor without a pulse. There are no complexes here.
- Disconnected lead — The leads are attached and two leads show the same flat line. Confirm connections and gain, then treat it as asystole — never assume a lead fault in a pulseless patient.