Rate of Ecg Calculation

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ECG Heart Rate Calculator

function calculateEcgHeartRate() { var rrInterval = parseFloat(document.getElementById("rrInterval").value); var paperSpeed = parseFloat(document.getElementById("paperSpeed").value); var smallBoxWidth = parseFloat(document.getElementById("smallBoxWidth").value); var ecgResultDiv = document.getElementById("ecgResult"); if (isNaN(rrInterval) || isNaN(paperSpeed) || isNaN(smallBoxWidth) || rrInterval <= 0 || paperSpeed <= 0 || smallBoxWidth <= 0) { ecgResultDiv.innerHTML = "Please enter valid positive numbers for all fields."; return; } // Method 1: Using R-R Interval directly (most accurate if R-R is known precisely) var heartRate1 = 60 / rrInterval; // Method 2: Using number of small boxes between R-R intervals // This method assumes we are measuring the R-R interval in terms of small boxes. // If the user input is already R-R interval in seconds, this calculation is not needed, // but we can infer the number of boxes if we assume a typical R-R duration. // For simplicity and directness, let's use the R-R interval in seconds provided by the user. // The paper speed and small box width are more relevant if the user is counting boxes. // If the user intended to count boxes, they would typically provide the number of boxes. // Let's assume the 'rrInterval' input is the direct time in seconds. var finalHeartRate = heartRate1; // Using the most direct calculation ecgResultDiv.innerHTML = "Estimated Heart Rate: " + finalHeartRate.toFixed(0) + " bpm"; }

Understanding ECG and Heart Rate Calculation

An Electrocardiogram (ECG or EKG) is a vital diagnostic tool that records the electrical activity of the heart over a period of time. This electrical activity is translated into waveforms on graph paper, allowing healthcare professionals to assess heart rhythm, rate, and detect various cardiac abnormalities.

How to Calculate Heart Rate from an ECG:

There are several methods to determine heart rate from an ECG tracing, depending on the regularity of the rhythm and the information available on the ECG strip. The most common and accurate methods involve measuring the time between successive R-waves (the peak of the QRS complex), which represent ventricular depolarization.

1. Using the R-R Interval (Most Accurate for Regular Rhythms):

This is the most direct and accurate method for calculating heart rate, especially when the heart rhythm is regular. The R-R interval is the time between two consecutive R-waves. The formula is:

Heart Rate (bpm) = 60 / R-R Interval (seconds)

For example, if the R-R interval is measured to be 0.8 seconds, the heart rate would be 60 / 0.8 = 75 beats per minute (bpm).

2. Using ECG Paper Measurements (When R-R Interval in Seconds is Not Directly Provided):

ECG machines typically print tracings on graph paper with standard grid lines. Each small box usually represents 0.04 seconds, and each large box (composed of 5 small boxes) represents 0.20 seconds. The paper speed is usually 25 mm/sec.

  • For Regular Rhythms: Count the number of small boxes between two consecutive R-waves.
    Heart Rate (bpm) = 1500 / Number of Small Boxes between R-R intervals
    (This formula derives from 60 seconds/minute * 1000 milliseconds/second / (number of boxes * 40 milliseconds/box) = 1500 / number of boxes)
  • For Irregular Rhythms: A more practical approach is to count the number of QRS complexes within a 6-second strip and multiply by 10.
    Heart Rate (bpm) = Number of QRS complexes in a 6-second strip * 10

The calculator above primarily uses the direct R-R interval in seconds for its calculation, assuming this value is precisely measured or known.

Example Calculation:

Let's assume an ECG tracing shows a consistent R-R interval of 0.75 seconds. Using the primary formula:

  • R-R Interval = 0.75 seconds
  • Heart Rate = 60 / 0.75 = 80 bpm

If, instead, you measured 30 small boxes between R-waves on an ECG strip and the paper speed was 25 mm/sec (meaning each small box is 0.04 sec), you would calculate:

  • Number of Small Boxes = 30
  • Heart Rate = 1500 / 30 = 50 bpm

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