ECG rhythm strip interpretation worksheet with answers

Free printable ECG rhythm strip interpretation worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
II25 mm/s · 10 mm/mV

Measure the PR interval on this lead II strip, in seconds.

lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
PR = s
2.Easy
II25 mm/s · 10 mm/mV

The rhythm on this lead II strip is regular. Use the 300 method (300 ÷ the number of large boxes between two consecutive R waves) to estimate the heart rate in beats per minute, rounded to a whole number.

lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
heart rate = bpm
3.Medium
II25 mm/s · 10 mm/mV

Measure the QT interval and the R–R interval on this regular lead II strip, then calculate the rate-corrected QTc with Bazett’s formula QTc = QT/√RR (both in seconds). Give the answer in seconds to three decimals.

lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
QTc = s
4.Medium
II25 mm/s · 10 mm/mV

This lead II strip shows atrial flutter. Measure the flutter-wave interval and find the atrial rate in beats per minute.

lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
atrial rate = bpm
5.Hard
II25 mm/s · 10 mm/mVventricular tachycardiatorsades de pointesatrial flutter, 2:1 conductionventricular fibrillation

Identify the rhythm on this lead II strip. Click your answer.

lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
  1. 1ventricular tachycardia
  2. 2torsades de pointes
  3. 3atrial flutter, 2:1 conduction
  4. 4ventricular fibrillation
6.Hard
II25 mm/s · 10 mm/mVsecond-degree AV block type II2:1 AV block (type undetermined)third-degree (complete) AV blocksecond-degree AV block type I (Wenckebach)

Interpret this lead II strip. Which interpretation can you defend from this single strip? Click your answer.

lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
  1. 1second-degree AV block type II
  2. 22:1 AV block (type undetermined)
  3. 3third-degree (complete) AV block
  4. 4second-degree AV block type I (Wenckebach)

Answer key

  1. 1. PR = 0.16 s
  2. 2. heart rate = 55 bpm
  3. 3. QTc = 0.38 s
  4. 4. atrial rate = 300 bpm
  5. 5. ventricular tachycardia
  6. 6. 2:1 AV block (type undetermined)

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