Free EKG practice · Paramedic

Free EKG rhythm practice

How many rhythms can you identify in 60 seconds? Read a 6-second strip and pick the rhythm. Get it right, or use up your tries, and the clock stops to show you the criteria that prove it. Every strip is drawn fresh, so you never memorize a picture. You learn the rhythm. No account needed.

This is the Paramedic set: all 31 rhythms you can name from the strip alone, from the sinus rhythms through the AV blocks to the arrest rhythms.

60-second rhythm challenge

How many rhythms can you identify in one minute? Every strip you get right counts. A wrong pick does not stop the clock. When you get a strip right, or use up your tries, the clock stops and shows you the answer and why.

Your high scoreNone yetNovice, Basic

Mode

Rhythms

11 core rhythms

11 rhythms in play

How to read a 6-second strip

Every strip here is 6 seconds long. The marks along the top count off the seconds, 0s to 6s. The paper runs at 25 mm a second, and each small box is 0.04 seconds.

Rate: count and multiply by 10

Rate comes first. Count the QRS complexes inside the 6 seconds and multiply by 10. Six seconds times 10 is a full minute, so the answer is beats per minute. Eight complexes is about 80. Four is about 40.

Then sort the number. Under 60 is slow. Over 100 is fast. In between is normal.

Then work the strip in order

Before you name anything, run the same steps every time.

Rate. Fast, slow, or normal?
Rhythm. Regular, regularly irregular, or irregularly irregular?
P waves. Are they there? All the same shape? One in front of every QRS?
PR interval. Normal is 0.12-0.20 seconds. Is it constant, getting longer, or not related to the QRS at all?
QRS width. Normal is under 0.12 seconds. Narrow means the signal came from above the ventricles. Wide means it started in the ventricles or got there by an abnormal path.
QT interval. Note it if it is long. A long QT sets up torsades de pointes.

Naming a rhythm off a first glance is how people talk themselves into the wrong answer. Work through the steps, and your answers tell you which rhythm it is.

Once you have a name, you are not done. The rhythm tells you what the electricity is doing. The patient tells you what to do about it.

The criteria for all 31 rhythms

These are the same criteria the game explains every strip with. Open a rhythm for its example strip, the rhythms it gets mistaken for, and its treatment.

Sinus rhythms

Normal sinus rhythm

Rate: 60-100
Rhythm: Regular
P waves: Upright, one before every QRS, all the same shape
PR interval: 0.12-0.20 s, constant
QRS: Under 0.12 s

Clincher: Every step of the six-step read is normal.

Sinus bradycardia

Rate: Under 60
Rhythm: Regular
P waves: Upright, one before every QRS
PR interval: 0.12-0.20 s, constant
QRS: Under 0.12 s

Clincher: A normal sinus complex, just slow.

Sinus tachycardia

Rate: Over 100
Rhythm: Regular
P waves: Upright, one before every QRS (can crowd into the T wave at speed)
PR interval: 0.12-0.20 s, constant
QRS: Under 0.12 s

Clincher: A normal sinus complex, just fast.

Sinus arrhythmia

Rate: Usually 60-100
Rhythm: Irregular in a smooth, repeating wave
P waves: Upright, one before every QRS
PR interval: 0.12-0.20 s, constant
QRS: Under 0.12 s

Clincher: The rate speeds up and slows down with breathing.

Atrial rhythms

Premature atrial complexes (PACs)

Rate: That of the underlying sinus rhythm
Rhythm: Regular, interrupted by early beats
P waves: The early beat has a P that looks different, and it can hide in the T wave before it
PR interval: Normal, can be a little shorter on the early beat
QRS: Under 0.12 s

Clincher: An early, abnormally shaped P wave.

Atrial fibrillation

Rate: Ventricular rate varies, here within a normal range
Rhythm: Irregularly irregular
P waves: None, just a chaotic fibrillatory baseline
PR interval: None
QRS: Under 0.12 s

Clincher: Irregularly irregular: no two R-R intervals match.

Atrial fibrillation with rapid ventricular response

Rate: Ventricular rate well over 100
Rhythm: Irregularly irregular
P waves: None, just a chaotic fibrillatory baseline
PR interval: None
QRS: Under 0.12 s

Clincher: Irregularly irregular and fast. March out the R-R intervals, the irregularity hides at speed.

Atrial flutter (4:1)

Rate: Atrial about 300; ventricular set by the conduction ratio
Rhythm: Regular at a fixed ratio
P waves: Sawtooth flutter waves instead of P waves
PR interval: None
QRS: Under 0.12 s

Clincher: Organized sawtooth waves near 300, conducted in a ratio (here 4:1).

Atrial flutter (2:1)

Rate: Atrial about 300; ventricular near 150
Rhythm: Regular
P waves: Sawtooth flutter waves, one of each pair buried in the QRS or T
PR interval: None
QRS: Under 0.12 s

Clincher: A regular narrow tachycardia at almost exactly 150 earns a hunt for buried flutter waves.

Multifocal atrial tachycardia

Rate: Over 100
Rhythm: Irregular
P waves: At least three different shapes
PR interval: Varies with the P wave
QRS: Under 0.12 s

Clincher: Fast and irregular with P waves of at least three shapes.

Supraventricular tachycardia

Rate: About 150-220
Rhythm: Regular, metronome-steady
P waves: Not visible, buried
PR interval: Not measurable
QRS: Under 0.12 s

Clincher: Narrow, very fast and regular. The narrow QRS is what separates it from V-tach.

Junctional rhythms

Junctional escape rhythm

Rate: 40-60
Rhythm: Regular
P waves: Absent, inverted, or hidden in the QRS
PR interval: None, or short with an inverted P
QRS: Under 0.12 s

Clincher: A narrow QRS with no upright P in front of it, at the junction's own 40-60.

Accelerated junctional rhythm

Rate: 60-100
Rhythm: Regular
P waves: Inverted, just before the QRS (or hidden in or after it)
PR interval: Short
QRS: Under 0.12 s

Clincher: Inverted P with a short PR at a normal rate: the impulse spreads backward into the atria.

Junctional tachycardia

Rate: Over 100
Rhythm: Regular
P waves: Inverted just before the QRS, retrograde just after it, or absent
PR interval: Short when the inverted P comes first, otherwise none
QRS: Under 0.12 s

Clincher: Narrow and regular over 100 with an inverted or missing P. Over 100 separates it from accelerated junctional (60-100). A visible inverted P separates it from SVT, where the P is buried; with no P at all the two can look the same and are treated the same way at first.

AV blocks

1st-degree AV block

Rate: That of the underlying rhythm
Rhythm: Regular
P waves: Upright, one before every QRS
PR interval: Over 0.20 s, the same on every beat
QRS: Under 0.12 s

Clincher: Every P conducts, just late. Nothing drops.

2nd-degree type I (Wenckebach)

Rate: Ventricular slower than atrial
Rhythm: Regularly irregular, in groups
P waves: Regular, more P waves than QRS complexes
PR interval: Lengthens beat after beat until a QRS drops
QRS: Under 0.12 s

Clincher: Longer, longer, longer, drop. Usually nodal and usually benign.

2nd-degree type II (Mobitz II)

Rate: Ventricular slower than atrial
Rhythm: Irregular where beats drop
P waves: Regular, more P waves than QRS complexes
PR interval: Constant on every conducted beat
QRS: Narrow here; can be wide

Clincher: A constant PR, then a QRS drops without warning. It sits below the node and can progress to complete block.

3rd-degree (complete) AV block

Rate: Atrial faster than ventricular. The escape runs 40-60 if junctional, 20-40 if ventricular
Rhythm: P-P regular and R-R regular, independently
P waves: Regular, marching through the QRS and T waves
PR interval: Different on every beat: no relationship
QRS: Wide here (a ventricular escape)

Clincher: Two rhythms that ignore each other: AV dissociation.