How to Calculate Heart Rate with Ecg

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How to Calculate Heart Rate from an ECG

Electrocardiograms (ECGs or EKGs) are vital diagnostic tools that record the electrical activity of the heart. One of the most fundamental pieces of information derived from an ECG is the heart rate, which tells us how many times the heart beats per minute. Calculating heart rate from an ECG tracing is a common task for healthcare professionals and can be done with a few simple measurements and a basic understanding of ECG paper or digital displays.

Understanding ECG Paper

Standard ECG paper is printed on a grid where each small square represents 0.04 seconds in duration, and each large square (made up of 5×5 small squares) represents 0.20 seconds. The horizontal axis represents time, and the vertical axis represents voltage. The R-R interval, the time between two consecutive R waves (the tallest peak in the QRS complex), is crucial for heart rate calculation.

Methods for Calculating Heart Rate

There are several common methods to calculate heart rate from an ECG:

  1. The 6-Second Strip Method: This is one of the easiest and most common methods for calculating heart rate, especially for irregular rhythms. Count the number of QRS complexes in a 6-second strip (which is 30 large squares) and multiply that number by 10. This gives you the heart rate in beats per minute (bpm).
  2. The Large Square Method (for regular rhythms): If the heart rhythm is regular, you can use the large squares between consecutive R waves. Divide 300 by the number of large squares between two R-R intervals. This provides a quick estimate. For example, if there are 4 large squares between R waves, the heart rate is approximately 300 / 4 = 75 bpm.
  3. The Small Square Method (for very precise measurements in regular rhythms): For even greater precision with regular rhythms, divide 1500 by the number of small squares between two R-R intervals. If there are 20 small squares between R waves, the heart rate is 1500 / 20 = 75 bpm.

This calculator primarily uses the second and third methods, which are suitable for regular rhythms. For irregular rhythms, the 6-second strip method is generally preferred.

ECG Heart Rate Calculator

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