• Step 1: Calculate rate.
• Step 2: Determine regularity.
• Step 3: Assess the P waves.
• Step 4: Determine PR interval.
• Step 5: Determine QRS duration.
Step 1: Calculate Rate
• Option 1
– Count the # of R waves in a 6 second rhythm strip, then multiply by 10.
– Reminder: all rhythm strips in the Modules are 6 seconds in length.
Interpretation? 9 x 10 = 90 bpm
• Option 2
– Find a R wave that lands on a bold line.
– Count the # of large boxes to the next R wave. If the second R wave is 1 large box away the rate is 300, 2 boxes - 150, 3 boxes - 100, 4 boxes - 75, etc.
– Memorize the sequence:
300 - 150 - 100 - 75 - 60 - 50
Step 2: Determine regularity
• Look at the R-R distances (using a caliper or markings on a pen or paper).
• Regular (are they equidistant apart)? Occasionally irregular? Regularly irregular? Irregularly irregular?
Interpretation? Regular
Step 3: Assess the P waves
• Are there P waves?
• Do the P waves all look alike?
• Do the P waves occur at a regular rate?
• Is there one P wave before each QRS?
Interpretation? Normal P waves with 1 P wave for every QRS
Step 4: Determine PR interval
• Normal: 0.12 - 0.20 seconds.
(3 - 5 boxes)
Interpretation?0.12 seconds
Step 5: QRS duration
• Normal: 0.04 - 0.12 seconds.
(1 - 3 boxes)
Interpretation? 0.08 seconds
Rhythm Summary
• Rate 90-95 bpm
• Regularity regular
• P waves normal
• PR interval 0.12 s
• QRS duration 0.08 s
Interpretation? Normal Sinus Rhythm