EKG Visual Reference Guide — The Firefighter Medic

NORMAL

Normal Sinus Rhythm (NSR)

Rate: 60–100 bpm

Regular P wave before every QRS

PR interval 0.12–0.20s

QRS <0.12s (narrow)

Regular R-R intervals

TREATMENT

No treatment needed — assess for underlying cause if symptomatic

SINUS

Sinus Bradycardia

Rate: <60 bpm

All features of NSR but rate <60

Prolonged R-R intervals

Normal P, QRS, T morphology

TREATMENT

Symptomatic: Atropine 0.5mg IV · Pacing if refractory · Dopamine/Epi drip

SINUS

Sinus Tachycardia

Rate: 100–150 bpm

All features of NSR but rate >100

P waves may be buried in T waves at fast rates

Regular rhythm

TREATMENT

Treat the underlying cause — pain, hypoxia, hypovolemia, fever, anxiety

ATRIAL

Rapid Atrial Fibrillation (A-Fib)

Atrial: 350–600 bpm · Ventricular: variable

Irregularly irregular — no two R-R intervals equal

No identifiable P waves — chaotic baseline

Narrow QRS (usually)

TREATMENT

Unstable → Synchronized cardioversion · Stable → Rate control (Cardizem, Amiodarone) · Anticoagulation

ATRIAL

Atrial Flutter

Atrial: 250–350 bpm · Ventricular: 75–150 bpm

Sawtooth "flutter waves" — classic pattern

Regular or regularly irregular ventricular rate

2:1, 3:1, or 4:1 conduction ratio

TREATMENT

Unstable → Synchronized cardioversion (50–100J) · Stable → Rate control · Ablation for recurrent cases

SVT

Supraventricular Tachycardia (SVT)

Rate: 150–250 bpm

Rapid, regular, narrow-complex tachycardia

P waves hidden within or after QRS

Abrupt onset and termination

TREATMENT

Vagal maneuvers → Adenosine 6mg rapid IV push (12mg x2 if needed) → Cardioversion if unstable

1° BLOCK

First-Degree AV Block

Rate: Normal · PR >0.20s

PR interval consistently >0.20s (one big box)

Every P wave conducts — no dropped beats

Regular rhythm, normal QRS

TREATMENT

Usually benign — monitor, identify cause (dig toxicity, electrolyte, inferior MI)

2° TYPE I

Second-Degree Block — Wenckebach

Progressive PR lengthening → dropped QRS

PR interval gets longer with each beat

Eventually a QRS is dropped — then resets

"Longer, longer, longer, drop — then you've got a Wenckebach"

TREATMENT

Symptomatic: Atropine · Often associated with inferior MI · Usually transient

2° TYPE II

Second-Degree Block — Mobitz II

Sudden dropped QRS, no PR change

PR interval CONSTANT — then suddenly drops a QRS

More dangerous than Type I — can progress to 3°

Infranodal block — wide QRS common

TREATMENT

Transcutaneous pacing ready · Atropine may worsen · Cardiology consult · Permanent pacemaker likely

3° BLOCK

Third-Degree (Complete) AV Block

Atrial: 60–100 · Ventricular: 20–40 bpm

P waves and QRS have NO relationship — complete dissociation

Both rhythms regular but independent

Ventricular escape rhythm — wide, slow QRS

TREATMENT

Transcutaneous pacing IMMEDIATELY if symptomatic · Dopamine/Epi drip · Definitive: transvenous pacer

V-TACH

Ventricular Tachycardia (V-Tach)

Rate: 100–250 bpm

Wide, bizarre QRS complexes (>0.12s)

Regular, rapid — monomorphic

No P waves or dissociated P waves

TREATMENT

Pulseless → CPR + Defib · With pulse, unstable → Sync cardioversion · Stable → Amiodarone 150mg IV

LETHAL

Ventricular Fibrillation (V-Fib)

No organized rate — chaotic

Completely chaotic — no P, QRS, or T

Coarse (recent) or fine (prolonged) waveform

PULSELESS — cardiac arrest

TREATMENT

CPR + Immediate defibrillation (200J biphasic) · Epi 1mg q3-5min · Amiodarone 300mg IVP · Identify H's & T's

POLYMORPHIC

Torsades de Pointes

Rate: 150–250 bpm · Twisting QRS axis

QRS complexes twist around baseline — "spindle" pattern

Caused by prolonged QT interval

Associated with hypomagnesemia, antiarrhythmics

TREATMENT

Magnesium Sulfate 1–2g IV over 5–10 min · Unstable → Defibrillation · Stop offending drugs · Correct electrolytes