ECG Heart Rate Calculator
Results:
Understanding ECG Heart Rate Calculation
Electrocardiograms (ECGs or EKGs) are vital tools for assessing the electrical activity of the heart. One of the primary pieces of information derived from an ECG is the heart rate, which tells us how many times the heart beats per minute. There are several ways to calculate heart rate from an ECG tracing, each suited to different scenarios and the data available.
Methods for Calculating Heart Rate from an ECG:
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Using the RR Interval: The RR interval is the time between two consecutive R waves on the ECG complex. This is the most accurate method when a regular rhythm is present. The formula is:
Heart Rate (beats per minute) = 60 / RR Interval (in seconds)
For example, if the RR interval is 0.8 seconds, the heart rate is 60 / 0.8 = 75 beats per minute. -
Using ECG Paper Speed: ECG machines typically run at a standard paper speed, most commonly 25 mm/s or 50 mm/s. Each small square on ECG graph paper is usually 1 mm wide, and each large square (made up of 5 small squares) is 5 mm wide.
- At 25 mm/s:
- To find beats per minute, count the number of large boxes between two R waves and divide 300 by that number. (300 / number of large boxes).
- If the rhythm is irregular, count the number of R waves in a 6-second strip and multiply by 10.
- At 50 mm/s:
- To find beats per minute, count the number of large boxes between two R waves and divide 600 by that number. (600 / number of large boxes).
- If the rhythm is irregular, count the number of R waves in a 3-second strip and multiply by 20.
QRS Duration:
The QRS complex represents the depolarization of the ventricles. A normal QRS duration typically ranges from 0.06 to 0.10 seconds (or 60 to 100 milliseconds). If the QRS duration is prolonged, it may indicate a conduction delay within the ventricles, such as a bundle branch block.
How This Calculator Works:
This calculator primarily uses the RR Interval method, which is the most direct and common way to calculate heart rate when an accurate RR interval is known. It also shows how to interpret the QRS duration.