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

This lead II rhythm is regular. Count the small boxes between two consecutive R waves and use the 1500 method to find 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

Measure the QT 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
QT = s
5.Hard
II25 mm/s · 10 mm/mVfirst-degree AV blocksecond-degree AV block type II2:1 AV block (type undetermined)second-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. 1first-degree AV block
  2. 2second-degree AV block type II
  3. 32:1 AV block (type undetermined)
  4. 4second-degree AV block type I (Wenckebach)
6.Hard
II25 mm/s · 10 mm/mVpaced rhythm, failure to capturesecond-degree AV block type IIidioventricular rhythmthird-degree (complete) AV block

This patient has a pacemaker. Interpret the 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. 1paced rhythm, failure to capture
  2. 2second-degree AV block type II
  3. 3idioventricular rhythm
  4. 4third-degree (complete) AV block

Answer key

  1. 1. PR = 0.12 s
  2. 2. heart rate = 115 bpm
  3. 3. QTc = 0.448 s
  4. 4. QT = 0.44 s
  5. 5. 2:1 AV block (type undetermined)
  6. 6. paced rhythm, failure to capture

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