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.
ECG rhythm strip interpretation worksheet with answers
1.Easy
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
2.Easy
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
3.Medium
Interpret this lead II rhythm strip. Which rhythm is it? 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
- 1normal sinus rhythm
- 2junctional rhythm
- 3first-degree AV block
- 4atrial fibrillation
4.Medium
This lead II strip shows sinus rhythm with one pause. Measure the pause, the R–R interval across it, in seconds.
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
pause = s
5.Hard
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
- 1second-degree AV block type II
- 22:1 AV block (type undetermined)
- 3sinus bradycardia
- 4third-degree (complete) AV block
6.Hard
This lead II strip shows a conduction problem between the atria and the ventricles. Which rhythm is it? 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
- 1second-degree AV block type I (Wenckebach)
- 2second-degree AV block type II
- 3junctional rhythm
- 4third-degree (complete) AV block
Answer key
- 1. heart rate = 107 bpm
- 2. PR = 0.36 s
- 3. junctional rhythm
- 4. pause = 1.4 s
- 5. 2:1 AV block (type undetermined)
- 6. third-degree (complete) AV block
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