II. Interpretation: General

1. Heart Rate may be estimated from a regular pulse
1. Count pulses for 6 seconds and multiply by 10
2. Count pulses for 15 seconds and multiply by 4
2. Maximal Heart Rate predicted by Age (may be used for Exercise target, typically 60-80% of maximum)
1. Maximal Heart Rate = 220 - Age
2. Women may be better estimated with St. James Women Take Heart Project Calculation
1. Maximal Heart Rate = 206 - (Age * 0.88)
2. Gulati (2010) Circulation 122(2):130-7 +PMID: 20585008 [PubMed]
3. Heart Rate changes during respiration (respiratory variation)
1. Heart Rate increases during inspiration
2. Heart Rate decreases during expiration

III. Interpretation: Estimate from EKG Tracing

1. Count Complexes in a 6 second EKG or Telemetry strip
1. Normal recording is 25 mm/sec (5 large boxes per second, 30 per 6 seconds)
2. Distance markers on EKG represent 15 large boxes (3 seconds)
3. Count QRS Complexes between spanning 2 distance markers (30 large boxes, 6 seconds)
4. Multiply complex count by 10 for Heart Rate per minute
2. Interval between complexes
1. Count large boxes (0.2 seconds) between complexes
2. Divide 300 by box count: 300, 150, 100, 75, 60, 50
1. 1 large box (200 ms or 0.2 seconds): 300 bpm
2. 2 large boxes (400 ms or 0.4 seconds): 150 bpm
3. 3 large box (600 ms or 0.6 seconds): 100 bpm
4. 4 large boxes (800 ms or 0.8 seconds): 75 bpm
5. 5 large box (1000 ms or 1.0 seconds): 60 bpm
6. 6 large boxes (1200 ms or 1.2 seconds): 50 bpm
7. 7 large box (1400 ms or 1.4 seconds): 43 bpm
8. 8 large boxes (1600 ms or 1.6 seconds): 37 bpm

IV. Interpretation: Background

1. Intrinsic Rates
1. Atria: 75
2. AV Node: 60
3. Ventricle: 40
2. Rough estimates to remember
1. Infant: 160
2. Preschool: 120
3. Teen: 100
3. Normal Heart Rate for age
1. Infant: 100-160
2. Toddler: 90-150
3. Preschool: 80-140
4. School-age: 70-120
5. Teen and adult: 60-100
4. References
1. Diekmann (2006) Pediatric Education for Prehospital Professionals, Jones and Bartlett

V. Interpretation

1. Bradycardia: under 60 (adults, see pediatric range above)
2. Normal Sinus Rhythm: 60 to 100 (adults, see pediatric range above)
3. Narrow Complex Tachycardia
1. Sinus Tachycardia: over 100
2. Supraventricular Tachycardia
1. Infants: over 220
2. Children: over 180
3. Adults: over 160
4. Wide Complex Tachycardia
1. Ventricular Tachycardia
2. Supraventricular Tachycardia with aberrancy