Adult health
ECG rhythms: recognize and act
NCLEX ECG map: normal sinus vs AF, VT, VF, and asystole — what the strip means and the first nursing moves.
Clesial Editorial TeamReviewed by Clesial Editorial Team, Clinical Content Review
Contents7 sections
ECG items ask whether you can name the danger and move — pulse check, CPR, defibrillation, or a calmer rate-control path. MI reperfusion urgency lives in Acute coronary syndromes. Electrolyte-driven peaked T waves live in Electrolytes. This chapter owns common rhythm recognition and the first nurse actions.
How to read a strip under time pressure
Start with the client: responsive? breathing? pulse? A perfect label on a dead monitor cable helps no one. Then rate, regularity, P waves, QRS width. Narrow complex usually means the ventricles are being activated over the normal pathway; wide complex raises ventricular origin or aberrancy — and with no pulse, you stop debating labels and run the pulseless algorithm.
Rhythms you must not confuse
| Rhythm | Strip cues | First nursing lane |
|---|---|---|
| Normal sinus | Regular; P before each QRS; adult rate ~60–100 | Continue assessment; treat the cause of symptoms if any |
| Atrial fibrillation | Irregularly irregular; absent clear P waves | ABCs; rate/symptom control as ordered; embolus risk teaching |
| Ventricular tachycardia | Wide, rapid QRS; may have pulse or not | Pulse check splits the path: pulseless → CPR/defib; unstable with pulse → cardioversion path |
| Ventricular fibrillation | Chaotic, no QRS | Pulseless — CPR and defibrillation; do not wait for a ‘better IV’ |
| Asystole | Flatline (confirm leads) | CPR + epinephrine path; not a defibrillation rhythm |
Why AF matters beyond the squiggle: the atria quiver instead of kick, clots can form, and stroke risk drives anticoagulation conversations. Why VF/pulseless VT matter: cardiac output is effectively zero — electricity (defibrillation) plus CPR is the chance to restart an organized rhythm. Why asystole is different: there is no fibrillating myocardium to reset with a shock; perfusion comes from compressions and drugs while you reverse causes.
The distractor that looks advanced is synchronizing a shock into VF, shocking asystole, or walking away from AF because ‘the rate looks okay’ while the client is hypotensive and diaphoretic. Edge case: artifact and loose leads mimic VF or asystole — glance at the client and the electrodes before you announce a code on a brushing-teeth strip.
Safety
Pulseless VT or VF: start CPR and defibrillate as soon as the defibrillator is ready. Do not delay the first shock for routine tasks.
Defibrillation vs synchronized cardioversion
Defibrillation is an unsynchronized shock for pulseless VF or pulseless VT — you are not aiming at a QRS because there is no meaningful QRS to synchronize to. Synchronized cardioversion times the shock to the QRS for selected unstable tachycardias with a pulse (shock, severe hypotension, acute pulmonary edema, ongoing ischemia) so you do not hit the T wave and create VF. Same machine family, different mode and different clinical gate.
- No pulse + VF/VT → defibrillation + CPR.
- Pulse + unstable tachyarrhythmia → synchronized cardioversion as ordered.
- Stable with pulse → ABCs, oxygen as needed, expert consultation / ordered meds — not random shocking.
Antidysrhythmic drug details (amiodarone, adenosine timing, digoxin hold parameters) appear on stems inside ordered pathways — know the rhythm lane first so you do not give a ‘rate control’ answer to a pulseless client.
Priority map
| Picture | First move |
|---|---|
| Chaotic strip, no pulse | CPR + defibrillation |
| Wide complex, no pulse | Treat as pulseless VT — CPR/defib |
| Flatline | Confirm leads; CPR + epinephrine path |
| Irregularly irregular, stable | Assess, ordered rate plan, embolus risk |
| Unstable tachy with pulse | Synchronized cardioversion path |
Revision
Must know
- 1Treat the client, not only the strip — check responsiveness, pulse, and ABCs with every lethal-looking rhythm.
- 2Normal sinus: regular, P before every QRS, rate ~60–100 in adults.
- 3Atrial fibrillation: irregularly irregular, no clear P waves — rate control, embolus risk, anticoagulation teaching as ordered.
- 4Pulseless VT or VF: defibrillation / ACLS path — CPR until the defibrillator is ready; do not delay for IV starts that block the shock.
- 5Asystole: not a shockable rhythm — high-quality CPR and epinephrine per ACLS; confirm leads/power so you are not treating a disconnected cable.
- 6Unstable tachycardia with pulse (shock, severe hypotension, acute heart failure, ischemia): synchronized cardioversion path as ordered — different from defibrillation for pulseless VF/VT.
Memory hooks
Pulse before the pad fantasy
A wide-complex strip without a pulse is a defibrillation/CPR problem, not a ‘watch and give oral meds’ problem.
Irregularly irregular = think AF
No organized P waves and chaotic timing point to atrial fibrillation until proven otherwise.
Flatline is CPR, not shock
Asystole does not get defibrillation; confirm the rhythm and run the CPR/drug path.
How it's tested
Stems show a strip description or label and ask the priority action, or contrast cardioversion with defibrillation. Distractors shock asystole, delay CPR for a second IV, or treat pulseless VT like stable sinus tach.
More in adult health
All topics- Acute coronary syndromesNCLEX ACS chapter: STEMI recognition and reperfusion urgency, nitroglycerin and cath-site priorities, cardiogenic shock after MI, and core cardiopulmonary assessment cues.Read
- Acute respiratory emergenciesNCLEX airway map: failure cues, PE vs pneumothorax vs obstruction, oxygen and positioning priorities, and when to escalate.Read
- AnemiasNCLEX hematology chapter: iron B12 and folate deficiency cues, anemia activity tolerance, sickle-cell crisis priorities, and when bleeding precautions apply.Read
- Antimicrobial therapyNCLEX antimicrobial chapter: allergy checks, finishing the course, vancomycin flushing, aminoglycoside toxicity, TB drug teaching, and common topical agents.Read