Five-Step
Method for
Rhythm
Interpretation
Normal Sinus Rhythm
1. Rate: 60-100
2. Rhythm: Atrial regular; Ventricular regular
3. P waves: One before each QRS; upright &
uniform
4. PR interval: 0.12-0.2 seconds
5. QRST: QRS complexes look alike, measure 0.060.12 seconds; no ST segment elevation
Step 1: Heart Rate
Six-second method: Use boxes or tic marks to
determine six seconds (30 large boxes). Count
number of PQRST complexes; multiply by ten.
Fast counting method: Count the number of large 0.2
second boxes between R waves.
Heart Rate = 300 ÷ (# of large squares)
Example: 300 ÷ 3 large boxes = HR 100
Step 2: Rhythm
Regular or Irregular?
• Consistent time between R-R intervals. Variation
less than 1.5 small boxes or 0.06 seconds.
Step 3: P Wave
•
•
•
•
Produced during R & L atrial depolarization
Represents SA node pacing or firing
Should be rounded and upright
Should be one for every QRS complex
•
Represents start of atrial depolarization to start of
ventricular depolarization
Measured from onset of P wave to onset of QRS
Should be regular and consistent
Normal = 0.12-0.20 seconds (3-5 small squares)
Step 4: PR Interval
•
•
•
Step 5: QRS & T Complexes
QRS: Represents depolarization of ventricles
• Normal = 0.06 – 0.12 seconds (1 ½ to 3 small
squares)
T-wave: Represents ventricular repolarization
• Should be shorter than R wave
• Onset of ST segment (J point) should be close to
baseline of PR interval ending
QT Interval: From onset of Q wave to end of T wave.
QTc (corrected for HR) normal = <0.470
J Point
Clinical Education
[ADVENTISTHEALTH:INTERNAL]
Origination Date 12.11.2020
Atrial Rhythms
Premature Atrial Contractions: Early P wave, with
normal QRS following
S/S
Atrial Flutter: Sawtooth pattern; Atrial rate 250-400
S/S
SOB
Dizziness
Weakness
Anxiety
Palpitation
Asymptomatic
Atrial Fibrillation: No P waves; Irregularly Irregular
S/S
Dizziness
SOB
Angina
Weakness
Supraventricular Tachycardia: QRS WNL; Rate >150;
buried P wave
S/S
Palpitation
Dizziness
SOB
Angina
Attempt vagal maneuver; adenosine
Idioventricular (V-escape): SA/AV node failure; 20-40
bpm (accelerated: 40-100 bpm)
S/S
Ventricular Rhythms
Premature Ventricular Contractions: Early wide
ventricular beat; bigeminy or trigeminy
S/S
Palpitation
Weakness
Dizziness
Ventricular Tachycardia: Wide & fast 100-300 bpm
S/S
Angina
Syncope
SOB
Ventricular Fibrillation: Coarse or fine; Torsades de
Pointes; no myocardial contraction
S/S
Loss of
consciousness
Pulseless
Emergent rhythm: Rapid Response/code; prep for defib
Emergent rhythm: Code Blue; CPR; defibrillation
Bundle Branch Block: QRS complex >0.12
1st Degree Heart Block: PR interval >0.20
S/S
Angina
Dizziness
Asymptomatic
Heart Blocks
Cool/mottled
Syncope
Hypotension
AMS
Emergent rhythm: Rapid Response/Code; Pacing; CPR
S/S
Typically
Asymptomatic
Example: Sinus rhythm with a BBB
Example: Sinus rhythm with 1st degree heart block
2nd Degree Heart Block Type 1: PR interval increases
until dropped beat occurs, aka Wenckebach
2nd Degree Heart Block Type 2: Random dropped
beats; may progress to 3rd degree block
S/S
Dizziness
Weakness
Palpitations
Longer longer drop: Wenckebach; May resp to atropine
rd
S/S
Syncope
Angina
Caution: Atropine may increase block; Apply pacer pads
Other (non-heart block)
Junctional: No P waves or inverted P waves; 40-60
S/S bpm; Accelerated J. 60-100 bmp; J. tach >100
3 Degree Heart Block: P waves and QRS complexes
dissociated
Angina
SOB
Syncope
Rapid Resp & transcutaneously pace if symptomatic
S/S
Dizziness
SOB
Weakness
This form does not constitute an official AHPL policy and serves as a guideline for recommended best practice. Certain situations may dictate variations
in practice.
Clinical Education
Origination Date 12.11.2020
[ADVENTISTHEALTH:INTERNAL]
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