ECG : Step-by-Step Guide to Calculating Heart Rate from ECG at Standard 25 mm s

Calculating heart rate from an ECG is a fundamental skill in cardiology. Here’s a step-by-step guide using images and explanations to help understand the process at the standard paper speed of 25 mm/s.

Step 1: Understand the ECG Paper Speed

• Standard Speed: ECG paper moves at 25 mm per second.
• Grid Layout: Each small square on the ECG paper represents 0.04 seconds, and each large square (consisting of 5 small squares) represents 0.2 seconds.
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Step 2: Identify the R-R Interval

• Locate R Waves: Identify two consecutive R waves on the ECG trace. The R-R interval is the distance between these two points.

Step 3: Measure the R-R Interval

• Count the Squares: Count the number of small squares between two consecutive R waves.
  • Example: If there are 20 small squares between two R waves.

Step 4: Calculate Heart Rate

• Formula Method: Use the formula to calculate the heart rate in beats per minute (bpm).
  • Formula: Heart Rate = 1500 / (Number of small squares between R waves)
  • Example: If there are 20 small squares, Heart Rate = 1500 / 20 = 75 bpm.

Alternative Method: Large Square Method

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