Cheat sheets › Cardiac

EKG rhythms cheat sheet

Read the strip in the same order every time: rate, regularity, P waves, PR interval, QRS. Then name the rhythm and know the first move.

The exam's favorite trap is shockable versus not shockable: V fib and pulseless V tach get the shock; asystole and PEA get CPR and epinephrine.

✔ Reviewed by a licensed RN· Updated Oct 2026· Sources

Rhythm	What you see	First treatment
Reading the strip	Rate: R waves in 6 s x 10; PR 0.12-0.20; QRS < 0.12	Regular vs irregular R-R P before every QRS?
Sinus bradycardia	Rate < 60, everything else normal	Only if symptomatic: atropine 1 mg Then pacing, dopamine, epi
Sinus tachycardia	Rate 101-150+, P before each QRS	Treat the cause: fever, pain, hypoxia, volume
Atrial fibrillation	Irregularly irregular, no P waves	Anticoagulate (stroke risk) Rate control: diltiazem, metoprolol
Atrial flutter	Sawtooth waves, atrial rate 250-350	Same logic as AF; ablation usually cures
SVT	150-250, regular, narrow, P hidden	Vagal, then adenosine 6 mg rapid push Unstable: synchronized cardioversion
PVCs	Early wide bizarre QRS, no P	Frequent, multifocal, runs, R-on-T = danger Check K+, Mg++, O2, dig level
V tach	100-250, wide QRS, regular	Pulse + stable: amiodarone Pulse + unstable: sync cardiovert No pulse: CPR + defibrillate
V fib	Chaotic, no waves, no pulse	DEFIBRILLATE now, CPR Epi q3-5 min, amiodarone 300
Asystole / PEA	Flat line / rhythm with no pulse	NOT shockable: CPR + epi Fix H's and T's
Heart blocks	1st: PR > 0.20 · Wenckebach: PR lengthens	Mobitz II: dropped QRS, no warning: pace 3rd degree: P and QRS independent: pace
Electrolyte clues	Peaked T = high K+ · U wave = low K+	Long QT = low Ca++ Torsades = give magnesium

RN pearl: V fib and pulseless V tach get the shock; asystole and PEA get CPR and epinephrine, never the paddles.

Watch: EKG rhythms explained

▶ EKG Rhythms Made Easy: Read Any Strip in 6 Steps + What to Do First (NCLEX Review) · 12:21 · free on the Nurse Lingo YouTube channel

Study this on your lock screen

NurseLingo turns topics like this into flashcards, practice questions with rationales and a study podcast. The printable PDF of this sheet is inside the app.

Get NurseLingo free

Test yourself: cardiac and EKG practice questions (free, answers and rationales included).

Frequently asked questions

How do you calculate heart rate on a 6-second strip?

Count the R waves in 6 seconds and multiply by 10.

Which EKG rhythms are shockable?

Ventricular fibrillation and pulseless ventricular tachycardia. Asystole and PEA are not shockable; they get CPR and epinephrine.

What does atrial fibrillation look like on an EKG?

An irregularly irregular rhythm with no clear P waves. The priorities are anticoagulation for stroke risk and rate control.

What is the first treatment for symptomatic sinus bradycardia?

Atropine 1 mg. If it doesn't work, pacing, dopamine or epinephrine come next. Bradycardia without symptoms isn't treated.

Keep studying

💓 Rhythm RushName the EKG rhythm before time runs out Electrolyte imbalances cheat sheetFluids & electrolytes Therapeutic drug levels cheat sheetPharmacology

Sources

Medical-Surgical Nursing, 12.2 Dysrhythmia, OpenStax
Pharmacology for Nurses, 22.2 Cardiac Emergency Drugs, OpenStax
Part 9: Adult Advanced Life Support, 2025 AHA Guidelines for CPR and ECC, American Heart Association, Circulation

For study only, not medical advice. Ranges and protocols vary by facility; follow your program and facility policies.