1. What is RR Interval?

The RR interval is the time between two consecutive R waves on an electrocardiogram (ECG). It represents the duration of one cardiac cycle and is used to calculate heart rate and assess rhythm regularity.

2. How to Measure RR Interval

RR interval is measured from peak of one R wave to peak of the next R wave on ECG. The standard unit is seconds.

Example: If RR interval is 0.8 seconds:

• Heart rate = 60 / 0.8 = 75 bpm

3. Clinical Significance

Normal Range: 0.6-1.0 seconds (60-100 bpm)

Variations:

• <0.6s: Tachycardia (>100 bpm)
• >1.0s: Bradycardia (<60 bpm)
• Irregular intervals: Arrhythmia

4. Using the Calculator

Steps:

1. Measure RR interval on ECG (in seconds)
2. Enter value in calculator
3. Get heart rate and interpretation

5. Frequently Asked Questions (FAQ)

Q1: What if my RR intervals vary?
A: Variable RR intervals suggest arrhythmia. Common causes include atrial fibrillation, sinus arrhythmia, or premature beats.

Q2: How accurate is this calculation?
A: Accurate for regular rhythms. For irregular rhythms, average several RR intervals.

Q3: What's the difference between RR and PP interval?
A: RR measures ventricular activity (R waves), PP measures atrial activity (P waves). They should be equal in normal sinus rhythm.

Q4: Can I use this for exercise ECG?
A: Yes, but normal ranges differ during exercise (expect tachycardia with exertion).

Q5: What about pediatric patients?
A: Normal ranges are higher in children (e.g., 70-170 bpm in infants).