Certified Rhythm Analysis Technician (CRAT) 2025 – 400 Free Practice Questions to Pass the Exam

To determine the correct sweep speed that allows 1 mm on the ECG to represent 400 milliseconds, it's essential to understand the relationship between time and the speed at which the paper moves.

ECG machines typically have a standard sweep speed of 25 mm/second, where each 1 mm on the ECG paper corresponds to 0.04 seconds, or 40 milliseconds. To find the sweep speed required for 1 mm to equal 400 milliseconds, you can use a proportion based on this standard.

If 1 mm equals 40 milliseconds at the standard speed, then to have 1 mm equal 400 milliseconds, the sweep speed must be reduced significantly since a longer duration would require paper to move more slowly.

Calculating this, if 1 mm = 40 milliseconds at 25 mm/second, then to represent 400 milliseconds, you need to set the speed to 25 mm/second divided by 10 (since 400 milliseconds is ten times longer than 40 milliseconds). Therefore, when the paper moves at 25 mm/second, 1 mm will indeed equal 400 milliseconds.

This understanding confirms that the correct setting for the recorder should be at 25 mm/second to achieve the desired time