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Heart rhythm practice. See the pattern before you name it.

Learn the visual cues commonly used to describe introductory rhythm patterns, then practice identifying simplified illustrative strips in a scored quiz.

Begin with the rhythm library

A simple visual sequence

Start with spacing, then scan the shapes.

Rate is one visual clue, not a standalone diagnosis. Compare it with beat spacing, atrial activity, and QRS appearance in the simplified examples below.

  1. 01

    Check the beat spacing

    Look for regular, irregular, or unexpectedly early beats.

  2. 02

    Look before the QRS

    Notice whether a consistent P wave is visible before each complex.

  3. 03

    Compare rate and width

    Use BPM as one clue, then compare narrow, wide, organized, and chaotic patterns.

Rhythm library

Nine simplified patterns to compare.

Each vector strip below is an original, simplified educational diagram made for this page. Rate is one identification clue—not a standalone diagnosis—and these examples are not clinical tracings.

Regular sinus pattern

Normal sinus rhythm

Illustrative

Rate criteria

Ventricular rate: 60–100 bpm

A simplified 72 bpm baseline pattern with 12 evenly spaced beats and a small P wave before each narrow QRS complex.

What to look for

  • R–R spacing appears even.
  • A similar P wave precedes each QRS.
  • QRS complexes look narrow in this illustration.
  • Ventricular rate is typically 60–100 bpm.

Compare it with: Unlike sinus bradycardia or sinus tachycardia, the same sinus pattern is neither notably slow nor notably fast.

A simplified 72 bpm baseline pattern with 12 evenly spaced beats and a small P wave before each narrow QRS complex. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

12 organized QRS complexes × 6 = 72 bpm · R–R ≈ 0.83 sec (20.8 small boxes)

Simplified original rhythm-strip diagram for educational comparison.

Slow regular sinus pattern

Sinus bradycardia

Illustrative

Rate criteria

Ventricular rate: below 60 bpm

A simplified 48 bpm sinus pattern with eight evenly spaced beats and a visible P-to-QRS relationship.

What to look for

  • R–R spacing is regular and noticeably wide.
  • A P wave appears before each QRS.
  • QRS complexes remain narrow in this illustration.
  • Ventricular rate is below 60 bpm.

Compare it with: Unlike a junctional rhythm, this diagram retains a consistent visible P wave before each QRS.

A simplified 48 bpm sinus pattern with eight evenly spaced beats and a visible P-to-QRS relationship. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

8 organized QRS complexes × 6 = 48 bpm · R–R = 1.25 sec (31.25 small boxes)

Simplified original rhythm-strip diagram for educational comparison.

Fast regular sinus pattern

Sinus tachycardia

Illustrative

Rate criteria

Ventricular rate: above 100 bpm (often 100–180)

A simplified 120 bpm sinus pattern with 20 regular beats; each narrow QRS remains preceded by a recognizable P wave.

What to look for

  • R–R spacing is regular and compressed.
  • A similar P wave leads each QRS.
  • QRS complexes are narrow in this illustration.
  • Ventricular rate is above 100 bpm, often about 100–180 bpm.

Compare it with: Unlike supraventricular tachycardia, this illustration still shows a recognizable P wave before each beat.

A simplified 120 bpm sinus pattern with 20 regular beats; each narrow QRS remains preceded by a recognizable P wave. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

20 organized QRS complexes × 6 = 120 bpm · R–R = 0.50 sec (12.5 small boxes)

Simplified original rhythm-strip diagram for educational comparison.

Irregularly irregular pattern

Atrial fibrillation

Illustrative

Rate criteria

Variable ventricular response: slow <60, controlled 60–100, rapid >100 bpm

A simplified 10-second strip with 13 irregularly spaced narrow QRS complexes and no repeating, organized P-wave pattern.

What to look for

  • R–R spacing varies without an obvious repeating cycle.
  • Distinct repeating P waves are not seen.
  • The baseline looks uneven between QRS complexes.
  • QRS complexes may remain narrow in this illustration.
  • Ventricular response varies: slow below 60, controlled 60–100, or rapid above 100 bpm.

Compare it with: Unlike atrial flutter, this pattern does not show a regular, repeating sawtooth-like atrial activity.

A simplified 10-second strip with 13 irregularly spaced narrow QRS complexes and no repeating, organized P-wave pattern. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

13 organized QRS complexes × 6 = 78 bpm average · intentionally variable R–R spacing

Simplified original rhythm-strip diagram for educational comparison.

Organized flutter-wave pattern

Atrial flutter

Illustrative

Rate criteria

Atrial rate: about 250–350 bpm; ventricular rate depends on conduction

A simplified 10-second strip with 50 organized flutter cycles (300/min) and 25 regular narrow QRS complexes (150/min), illustrating 2:1 conduction.

What to look for

  • A repeating flutter-wave contour is visible between QRS complexes.
  • Atrial activity appears organized rather than chaotic.
  • The ventricular response may be regular in this illustration.
  • QRS complexes appear narrow here.
  • Atrial rate is often about 250–350 bpm; 2:1 conduction can produce a ventricular rate near 150 bpm.

Compare it with: Unlike atrial fibrillation, the atrial activity follows a repetitive visual pattern rather than a variable baseline.

A simplified 10-second strip with 50 organized flutter cycles (300/min) and 25 regular narrow QRS complexes (150/min), illustrating 2:1 conduction. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

25 QRS complexes × 6 = 150 bpm · regular 2:1-conduction illustration

Simplified original rhythm-strip diagram for educational comparison.

Very rapid narrow-complex pattern

Supraventricular tachycardia

Illustrative

Rate criteria

Ventricular rate: usually 150–250 bpm

A simplified rapid, regular 180 bpm narrow-complex pattern; P waves are not clearly separated at this illustrated speed.

What to look for

  • R–R spacing is very regular and close together.
  • Ventricular rate is usually about 150–250 bpm.
  • QRS complexes are narrow in this illustration.
  • P waves are not clearly separate from the fast rhythm.

Compare it with: Unlike sinus tachycardia, this simplified example does not show a clearly separated P wave before every QRS.

A simplified rapid, regular 180 bpm narrow-complex pattern; P waves are not clearly separated at this illustrated speed. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

30 QRS complexes × 6 = 180 bpm · R–R ≈ 0.33 sec (8.3 small boxes)

Simplified original rhythm-strip diagram for educational comparison.

Early wide-complex interruption

Premature ventricular complexes

Illustrative

Rate criteria

Rate: describe the underlying rhythm; a PVC has no separate BPM

A simplified 72 bpm underlying sinus schedule interrupted by one early, wider-looking beat; its coupling interval plus pause equals two expected sinus cycles.

What to look for

  • Most beats follow a regular sinus-like pattern.
  • One beat arrives earlier than expected.
  • The early beat has a wider, different-looking QRS shape.
  • A longer pause follows the early beat in this illustration.
  • Describe the underlying rhythm rate rather than assigning the premature beat its own BPM.

Compare it with: Unlike ventricular tachycardia, this example shows an isolated early wide complex rather than a sustained fast run of wide complexes.

A simplified 72 bpm underlying sinus schedule interrupted by one early, wider-looking beat; its coupling interval plus pause equals two expected sinus cycles. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

Underlying sinus schedule: 12 QRS × 6 = 72 bpm · early PVC and full compensatory pause

Simplified original rhythm-strip diagram for educational comparison.

Fast wide-complex run

Ventricular tachycardia

Illustrative

Rate criteria

Ventricular rate: usually 100–250 bpm

A simplified 150 bpm sustained pattern with 25 broad, repeating complexes at regular 0.40-second intervals.

What to look for

  • Ventricular rate is usually about 100–250 bpm and may be generally regular.
  • QRS complexes are wide and similar in shape.
  • A clear P-to-QRS relationship is not visible here.
  • The wide complexes continue as a run.

Compare it with: Unlike premature ventricular complexes, this diagram shows repeated wide complexes in succession rather than a single interruption.

A simplified 150 bpm sustained pattern with 25 broad, repeating complexes at regular 0.40-second intervals. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

25 broad QRS complexes × 6 = 150 bpm · R–R = 0.40 sec (10 small boxes)

Simplified original rhythm-strip diagram for educational comparison.

Chaotic disorganized pattern

Ventricular fibrillation

Illustrative

Rate criteria

Rate: no organized measurable ventricular rate

A simplified chaotic waveform with no organized repeating QRS complexes.

What to look for

  • No consistent QRS complexes can be identified.
  • The waveform varies in height and spacing.
  • There is no organized repeating rhythm.
  • There is no organized measurable ventricular rate.
  • This illustration is intentionally schematic, not a diagnostic tracing.

Compare it with: Unlike ventricular tachycardia, this pattern has no regular sequence of repeated wide complexes.

A simplified chaotic waveform with no organized repeating QRS complexes. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

No organized measurable rate · disorganized schematic activity

Simplified original rhythm-strip diagram for educational comparison.

Visual practice test

Identify ten simplified rhythm strips.

Choose the best label from the options. This practice test evaluates recognition of the diagrams on this page—not a real patient tracing.

Selections work with a mouse, touch, or keyboard. Color is never the only answer cue.

1. Which simplified pattern is shown?
A simplified 72 bpm baseline pattern with 12 evenly spaced beats and a small P wave before each narrow QRS complex. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

12 organized QRS complexes × 6 = 72 bpm · R–R ≈ 0.83 sec (20.8 small boxes)

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
2. Which simplified pattern is shown?
A simplified 48 bpm sinus pattern with eight evenly spaced beats and a visible P-to-QRS relationship. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

8 organized QRS complexes × 6 = 48 bpm · R–R = 1.25 sec (31.25 small boxes)

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
3. Which simplified pattern is shown?
A simplified 120 bpm sinus pattern with 20 regular beats; each narrow QRS remains preceded by a recognizable P wave. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

20 organized QRS complexes × 6 = 120 bpm · R–R = 0.50 sec (12.5 small boxes)

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
4. Which simplified pattern is shown?
A simplified 10-second strip with 13 irregularly spaced narrow QRS complexes and no repeating, organized P-wave pattern. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

13 organized QRS complexes × 6 = 78 bpm average · intentionally variable R–R spacing

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
5. Which simplified pattern is shown?
A simplified 10-second strip with 50 organized flutter cycles (300/min) and 25 regular narrow QRS complexes (150/min), illustrating 2:1 conduction. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

25 QRS complexes × 6 = 150 bpm · regular 2:1-conduction illustration

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
6. Which simplified pattern is shown?
A simplified rapid, regular 180 bpm narrow-complex pattern; P waves are not clearly separated at this illustrated speed. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

30 QRS complexes × 6 = 180 bpm · R–R ≈ 0.33 sec (8.3 small boxes)

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
7. Which simplified pattern is shown?
A simplified 72 bpm underlying sinus schedule interrupted by one early, wider-looking beat; its coupling interval plus pause equals two expected sinus cycles. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

Underlying sinus schedule: 12 QRS × 6 = 72 bpm · early PVC and full compensatory pause

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
8. Which simplified pattern is shown?
A simplified 150 bpm sustained pattern with 25 broad, repeating complexes at regular 0.40-second intervals. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

25 broad QRS complexes × 6 = 150 bpm · R–R = 0.40 sec (10 small boxes)

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
9. Which simplified pattern is shown?
A simplified chaotic waveform with no organized repeating QRS complexes. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

No organized measurable rate · disorganized schematic activity

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.
10. Which simplified pattern is shown?
A simplified 72 bpm underlying sinus schedule interrupted by one early, wider-looking beat; its coupling interval plus pause equals two expected sinus cycles. This original educational diagram spans 10 seconds; each small box represents 0.04 seconds and each bold box represents 0.20 seconds. It is not a diagnostic ECG recording.10-SECOND RHYTHM STRIP0 s10 sillustrative timing scale · 25 mm/s
Timing: 1 small box = 0.04 secbold box = 0.20 sec5 bold boxes = 1 sec

Underlying sinus schedule: 12 QRS × 6 = 72 bpm · early PVC and full compensatory pause

Original simplified rhythm-strip illustration. Choose the label that best matches the visible pattern.

Answer all 10 questions to unlock your score.

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Safety reminder: this educational content cannot assess symptoms or determine a diagnosis. Seek urgent medical care or local emergency help for concerning symptoms such as chest pain, fainting, severe shortness of breath, or a sudden sense that something is seriously wrong.