Rate Calculation in Atrial Fibrillation

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Atrial Fibrillation (AFib) Rate Calculator

Accurately determine average heart rate for irregular rhythms

6 Seconds (Standard EKG Strip) 10 Seconds (Standard 12-Lead EKG) 3 Seconds 15 Seconds 60 Seconds (Full Minute)
Calculated Heart Rate:
BPM

How to Calculate Heart Rate in Atrial Fibrillation

Calculating heart rate in Atrial Fibrillation (AFib) differs from regular rhythms like Normal Sinus Rhythm. Because AFib is "irregularly irregular," you cannot simply measure the distance between two R-waves (the 300-150-100 rule) as it changes with every beat.

The 6-Second Method

The clinical gold standard for bedside AFib rate calculation is the 6-second method. This is because it provides an average rate over a sufficient period to account for the variability of the ventricular response.

  • Step 1: Obtain a 6-second EKG rhythm strip. On standard EKG paper (25mm/sec), 6 seconds is represented by 30 large squares.
  • Step 2: Count the number of QRS complexes (the spikes) within those 30 large squares.
  • Step 3: Multiply the number of complexes by 10 to get the Beats Per Minute (BPM).

Clinical Examples

Example 1: You count 9 R-waves on a 6-second strip.
Calculation: 9 × 10 = 90 BPM (Controlled AFib).

Example 2: You count 14 R-waves on a 6-second strip.
Calculation: 14 × 10 = 140 BPM (AFib with Rapid Ventricular Response or RVR).

Understanding the Results

Rate Range Classification
Below 60 BPM Slow Ventricular Response (Bradycardia)
60 – 100 BPM Controlled AFib
Above 100 BPM Rapid Ventricular Response (RVR / Tachycardia)
function calculateAFibRate() { var qrsCount = document.getElementById('qrsCount').value; var duration = document.getElementById('timeDuration').value; var resultDiv = document.getElementById('afibResult'); var bpmOutput = document.getElementById('bpmOutput'); var rateStatus = document.getElementById('rateStatus'); if (qrsCount === "" || qrsCount <= 0) { alert("Please enter a valid number of QRS complexes."); return; } var qrs = parseFloat(qrsCount); var seconds = parseFloat(duration); // Formula: (Beats / Seconds) * 60 = BPM var bpm = Math.round((qrs / seconds) * 60); resultDiv.style.display = "block"; bpmOutput.innerHTML = bpm; if (bpm = 60 && bpm <= 100) { rateStatus.innerHTML = "Controlled Ventricular Rate"; rateStatus.style.backgroundColor = "#d4edda"; rateStatus.style.color = "#155724"; resultDiv.style.backgroundColor = "#f8fff9"; } else { rateStatus.innerHTML = "Rapid Ventricular Response (RVR)"; rateStatus.style.backgroundColor = "#f8d7da"; rateStatus.style.color = "#721c24"; resultDiv.style.backgroundColor = "#fff8f8"; } // Smooth scroll to result resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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