Chart — Cardiac
EKG Rhythm Chart
Bedside recognition reference for 14 common cardiac rhythms — rate, regularity, P wave, PR interval, QRS criteria, and key identification features with clinical significance and immediate nursing priorities.
Educational use only. Always assess the patient before acting on monitor findings. Rhythm identification requires clinical correlation. Follow your institution’s protocols and scope of practice. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
NormalMonitorUrgentArrest— Clinical urgency tier
Rhythm Recognition Reference
| Rhythm | Rate (bpm) | Regularity | P Wave | PR Interval | QRS | Key Recognition Feature |
|---|---|---|---|---|---|---|
Normal Sinus Rhythm (NSR)Normal | 60–100 | Regular | Upright in lead II; 1 P per QRS | 0.12–0.20 s | < 0.12 s (narrow) | All five criteria met — the baseline normal rhythm |
Sinus BradycardiaMonitor | < 60 | Regular | Upright in lead II; 1 P per QRS | 0.12–0.20 s | Narrow | Looks like NSR — rate is the only difference |
Sinus TachycardiaMonitor | 100–160 | Regular | Present; may be buried in preceding T wave at fast rates | Normal (may shorten slightly) | Narrow | NSR pattern — just faster; always has an underlying cause |
Atrial FibrillationUrgent | Atrial: chaotic; Ventricular: 60–160+ | Irregularly irregular | Absent — chaotic fibrillatory baseline | Absent | Narrow (usually); wide if aberrant conduction | No two R-R intervals are equal — no pattern to the irregularity |
Atrial FlutterUrgent | Atrial: 250–350; Ventricular: depends on AV ratio | Usually regular; variable if AV ratio varies | Sawtooth flutter waves (F waves) at ~300/min | Variable — determined by flutter:QRS ratio | Narrow | Classic sawtooth in II, III, aVF, V1; 2:1 ratio gives ventricular rate ~150 |
SVT (Supraventricular Tachycardia)Urgent | 150–250 | Regular | Hidden in QRS or T wave; retrograde (inverted) if visible | Not measurable | Narrow (unless aberrant conduction) | Abrupt onset and termination; regular narrow tachycardia |
First-Degree AV BlockMonitor | 60–100 | Regular | Present; 1 P per QRS | > 0.20 s (prolonged) | Narrow | All P waves conduct — just delayed; PR > 1 large box (5 small squares) |
Second-Degree AV Block Type I (Wenckebach)Monitor | Variable | Irregular (grouped beating pattern) | Present; more P waves than QRS complexes | Progressively lengthens → then one P wave is blocked (no QRS) | Narrow | PR gets longer, longer, longer — then a P wave with no QRS (dropped beat) |
Second-Degree AV Block Type IIUrgent | Variable (slower due to dropped beats) | Regular until dropped beat; then irregular | Present; more P waves than QRS complexes | Constant — then suddenly a P wave is not conducted without warning | Narrow or wide (often bundle branch block) | Fixed PR — unexpected dropped beat; no lengthening pattern |
Third-Degree (Complete) AV BlockUrgent | Atrial: varies; Ventricular: 20–60 | Both P and QRS regular — but independent of each other | Present; firing at own rate; NO relationship to QRS | No consistent PR — constantly changes | Wide (ventricular escape) or narrow (junctional escape) | Complete AV dissociation — P waves and QRS complexes march through independently |
Ventricular Tachycardia (VT)Arrest | 100–250 | Regular | Absent or AV dissociation | Not measurable | ≥ 0.12 s (wide, bizarre morphology) | Wide bizarre complexes at fast rate — immediately assess for pulse |
Ventricular Fibrillation (VF)Arrest | No measurable rate | Chaotic — no pattern | Absent | Absent | No organized QRS complexes | Disorganized chaotic waveform with no identifiable QRS |
Pulseless Electrical Activity (PEA)Arrest | Organized electrical activity visible on monitor | Varies — depends on underlying rhythm | May be present | Varies | Varies — may look near-normal | Organized electrical activity on monitor — NO palpable pulse |
AsystoleArrest | None | None | Absent | Absent | Absent | Flat line — confirm in 2 leads; do not treat fine VF as asystole |
Clinical Significance & Nursing Priorities
| Rhythm | Clinical Significance & Priorities |
|---|---|
| Normal Sinus Rhythm (NSR) | Normal cardiac conduction. Document as baseline. Any deviation requires identification. |
| Sinus Bradycardia | May be normal (athletes, sleep, vagal tone). Treat only if symptomatic: hypotension, altered LOC, syncope → atropine 1 mg IV q3–5 min (max 3 mg). |
| Sinus Tachycardia | Always reactive. Identify and treat the cause: pain, fever, hypovolemia, anxiety, sepsis, hypoxia, medications. Treating tachycardia without addressing cause is dangerous. |
| Atrial Fibrillation | Embolic stroke risk — assess anticoagulation status. Determine rate vs. rhythm control strategy. New-onset AFib with hemodynamic instability → cardioversion. |
| Atrial Flutter | Similar stroke risk to AFib. 2:1 AV conduction (most common) produces ventricular rate ~150 bpm — easily missed as sinus tachycardia. Look for hidden F-waves. |
| SVT (Supraventricular Tachycardia) | Usually AVNRT (most common). Vagal maneuvers first; adenosine 6 mg IV if vagal fails. Unstable SVT → synchronized cardioversion. Often self-terminating. |
| First-Degree AV Block | Usually benign. Every P wave still conducts. Monitor for progression to higher-degree block. May be caused by increased vagal tone, beta-blockers, digitalis, or myocarditis. |
| Second-Degree AV Block Type I (Wenckebach) | Block occurs at AV node. Usually benign and reversible. Grouped beating pattern is characteristic. Monitor for progression to Type II or complete block. |
| Second-Degree AV Block Type II | Block occurs below AV node (His-Purkinje). Higher risk than Type I — can progress suddenly to complete heart block. Pacemaker often required. Notify provider immediately. |
| Third-Degree (Complete) AV Block | Medical emergency. Atria and ventricles controlled by independent pacemakers. Hemodynamic compromise is common. Transcutaneous pacing preparation and immediate provider notification required. |
| Ventricular Tachycardia (VT) | Check pulse immediately. With pulse + stable: amiodarone IV. With pulse + unstable: synchronized cardioversion. Pulseless VT: CPR + defibrillation (treat as VF). |
| Ventricular Fibrillation (VF) | Cardiac arrest. Immediately: CPR → defibrillation → CPR → epinephrine → amiodarone. Coarse VF defibrillates more reliably than fine VF. Confirm in 2 leads before treating fine VF as asystole. |
| Pulseless Electrical Activity (PEA) | Cardiac arrest. CPR immediately. Identify and treat reversible causes: H's (hypovolemia, hypoxia, H+, hypo/hyperkalemia, hypothermia) and T's (tension pneumo, tamponade, toxins, thrombosis). |
| Asystole | Cardiac arrest with poorest prognosis. CPR immediately + epinephrine 1 mg IV q3–5 min. Confirm true asystole in 2 leads — fine VF can look like asystole and is defibrillatable. |
AV Block Quick Comparison
1st Degree
All P waves conduct. PR only prolonged. Benign.
2nd Degree Type I (Wenckebach)
PR lengthens progressively → dropped beat. Block at AV node. Usually benign.
2nd Degree Type II
Fixed PR → sudden dropped beat (no warning). Block below AV node. Higher risk. May need pacing.
3rd Degree (Complete)
No P-to-QRS relationship. Complete AV dissociation. Medical emergency — pacing required.
Cardiac Arrest Rhythms — ACLS Overview
Shockable
VF and pulseless VT → CPR + defibrillation
Non-Shockable
PEA and Asystole → CPR + epinephrine; address reversible causes (H’s & T’s)
In all arrest rhythms: call for help, initiate CPR, apply defibrillator pads, establish IV/IO access, and follow ACLS algorithm.
Related Resources
EKG BasicsRate calculation, regularity, P wave recognition — start here for rhythm reading
Open →ECG Interpretation Fundamentals9-step systematic method for analyzing any rhythm strip
Open →Rhythm Comparison ChartEducational side-by-side comparison of 8 major rhythms with narrative explanations
Open →Heart Blocks Reference1st, 2nd (Mobitz I & II), and 3rd-degree AV block quick reference
Open →AV Block Comparison ChartAll four degrees of AV block compared in detail
Open →ACLS Rhythm IdentificationShockable vs. non-shockable rhythms with immediate response priorities
Open →Recognizing Lethal RhythmsVF, pulseless VT, PEA, and asystole — bedside nursing priorities
Open →Standards & sources
Fact-checked Jun 20, 2026This page is written to align with AHA / ACC ECG Standards / ACLS Guidelines. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →