On a regular ECG running at 25 mm/s, the R–R interval is 4 large squares. What is the heart rate?
Answer and explanation
Correct answer: C. 75 beats/min
- Step 1: Heart rate .
- Step 2: beats/min.
Answer
75 beats/min.
Why not the others: 240 beats/min: The number of squares was multiplied by 60. 375 beats/min: Small squares (1500) were used with large squares. 37.5 beats/min: 300 was halved.
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