Using the 300 method on a regular rhythm, a technician counts four large boxes between two consecutive R waves. What is the heart rate?

Giải thích

The 300 method divides 300 by the number of large boxes between R waves, so 300 divided by 4 equals 75 beats per minute. Sixty would require five large boxes, 100 would require three, and 150 would require two. The method only works when the rhythm is regular, because it assumes every R-R interval is the same.