2 rate & rhythms

12-Lead Electrocardiography

a comprehensive course

Adam Thompson, EMT-P, A.S.

Rate &

Rhythms

Rate & Rhythm

• Interpret the rhythm– Identify the rate– Is it regular or irregular?– Identify P-waves– Identify PR-interval

Rate & Rhythm

Calculate the Rate

150 100 75 60300

Rate & Rhythm

• Is the rate too fast or too slow?• Intrinsic Rates:

– SA Node - 60 to 100– AV Junction - 40 to 60– Purkinje Fibers - 20 to 40

Rate & Rhythm

Regular or Irregular

Rate & Rhythm

P-Waves

• Are P-waves present?• Is there a P-wave for every QRS?• Is there a QRS for every P-wave?• Do the P-waves appear after the QRS?

Rate & Rhythm

PR-Interval

• Is the PR-interval consistent?• Is the PR-interval > 0.20 sec (200ms)?• Does the PR-interval lengthen?

Rate & Rhythm

• The next step is to interpret the rhythm that the patient is in.

• The following is a brief ECG arrhythmia review.

Sinus Rhythms

Normal Sinus Rhythm• Rate: 60 - 100 bpm• Rhythm: Regularly Regular• P wave: Present• P:QRS ratio: 1 to 1• PR-interval: Normal• QRS Width: < 120 ms (0.12 sec)

Normal Sinus Rhythm

Sinus Arrhythmia• Rate: 60 - 100 bpm• Rhythm: Varies with respiration• P wave: Present• P:QRS ratio: 1 to 1• PR-interval: Normal• QRS Width: < 120 ms (0.12 sec)

Sinus Arrhythmia

Sinus Bradycardia• Rate: < 60 bpm• Rhythm: Regularly-Regular• P wave: Present• P:QRS ratio: 1 to 1• PR-interval: Normal• QRS Width: < 120 ms (0.12 sec)

Sinus Bradycardia

Sinus Tachycardia• Rate: > 100 bpm• Rhythm: Regularly-Regular• P wave: Present• P:QRS ratio: 1 to 1• PR-interval: Normal• QRS Width: < 120 ms (0.12 sec)

Sinus Tachycardia

Sinus Pause/Arrest• Rate: Varies• Rhythm: Irregular• P wave: Present except for pause• P:QRS ratio: 1 to 1• PR-interval: Normal• QRS Width: < 120 ms (0.12 sec)

Premature Atrial Contraction• Rate: Determine underlined rate• Rhythm: Irregular• P wave: Present, may be different w/ PAC• P:QRS ratio: 1 to 1• PR-interval: Normal, may vary w/ PAC• QRS Width: < 120 ms (0.12 sec)

Ectopic Atrial Tachycardia• Rate: 100 - 180 bpm• Rhythm: Regular• P wave: Present, may be different w/ ectopy• P:QRS ratio: 1 to 1• PR-interval: Normal, different w/ ectopy• QRS Width: < 120 ms (0.12 sec)

Wandering Atrial Pacemaker• Rate: < 100 bpm• Rhythm: Irregularly-Irregular• P wave: At least 3 different morphologies• P:QRS ratio: 1 to 1• PR-interval: Variable• QRS Width: < 120 ms (0.12 sec)

Multifocal Atrial Tachycardia• Rate: > 100 bpm• Rhythm: Irregularly-Irregular• P wave: At least 3 different morphologies• P:QRS ratio: 1 to 1• PR-interval: Variable• QRS Width: < 120 ms (0.12 sec)

Atrial Flutter

Atrial Flutter• Rate: Atria (250-350), Ventricles (125-175)• Rhythm: Usually Regular• P wave: Saw toothed “F waves”• P:QRS ratio: Variable, 2:1 is common• PR-interval: Variable• QRS Width: < 120 ms (0.12 sec)

Atrial Flutter

3:1

Atrial Flutter

2:1

Atrial Fibrillation

Atrial Fibrillation• Rate: Variable, depending on ventricles• Rhythm: Irregularly-Irregular• P wave: None, chaotic atrial activity• P:QRS ratio: None• PR-interval: None• QRS Width: < 120 ms (0.12 sec)

Atrial Fibrillation

Premature Junctional Contraction

• Rate: Determine underlying rhythm• Rhythm: Irregular• P wave: none, antegrade, or retrograde• P:QRS ratio: 1:1 or retrograde• PR-interval: None, short, or retrograde• QRS Width: < 120 ms (0.12 sec)

Junctional Escape Beat

• Rate: Determine underlying rhythm• Rhythm: Irregular• P wave: none, antegrade, or retrograde• P:QRS ratio: 1:1 or retrograde• PR-interval: None, short, or retrograde• QRS Width: < 120 ms (0.12 sec)

Junctional Rhythm

• Rate: 40 - 60 bpm• Rhythm: Regular• P wave: none, antegrade, or retrograde• P:QRS ratio: 1:1 or retrograde• PR-interval: None, short, or retrograde• QRS Width: < 120 ms (0.12 sec)

Accelerated Junctional Rhythm

• Rate: 60 - 100 bpm• Rhythm: Regular• P wave: none, antegrade, or retrograde• P:QRS ratio: 1:1 or retrograde• PR-interval: None, short, or retrograde• QRS Width: < 120 ms (0.12 sec)

Narrow Complex Tachycardia

Sinus Tach

MAT

Ectopic A-Tach

Junctional

AVNRT/AVRT

A-Flutter

P

P

P

P

P

F F F F

P FP-Wave Flutter Wave

Premature Ventricular Contraction

• Rate: Determine underlying rhythm• Rhythm: Irregular• P wave: None with PVC• P:QRS ratio: None• PR-interval: None• QRS Width: > 120 ms (0.12 sec) WIDE


• Polymorphic– More than one one shape of QRS complex

• Multifocal– More than one focus or site of initial

impulse.


1 2

Ventricular Escape Beat

• Rate: Determine underlying rhythm• Rhythm: Irregular• P wave: None with PVC• P:QRS ratio: None• PR-interval: None• QRS Width: > 120 ms (0.12 sec) WIDE

Ventricular Rhythms

Idioventricular Rhythm

• Rate: 20 - 40 bpm• Rhythm: Regular• P wave: None• P:QRS ratio: None• PR-interval: None• QRS Width: > 120 ms (0.12 sec) WIDE

Idioventricular Rhythm

Accelerated Ventricular Rhythm

• Rate: 40 - 100 bpm• Rhythm: Regular• P wave: None• P:QRS ratio: None• PR-interval: None• QRS Width: > 120 ms (0.12 sec) WIDE

Ventricular Tachycardia

• Rate: 100 - 200 bpm• Rhythm: Regular• P wave: None, complete AV disassociation• P:QRS ratio: None• PR-interval: None• QRS Width: > 120 ms (0.12 sec) WIDE

Ventricular Tachycardia

Torsade de Pointes

• Rate: 200 - 250 bpm• Rhythm: Irregular• P wave: None• P:QRS ratio: None• PR-interval: None• QRS Width: > 120 ms (0.12 sec) WIDE

Ventricular Fibrillation

• Rate: Indeterminate• Rhythm: Chaotic• P wave: None• P:QRS ratio: None• PR-interval: None• QRS Width: None

1st Degree Heart Block

• Rate: Identify underlying rate• Rhythm: Regular• P wave: Present• P:QRS ratio: 1 to 1• PR-interval: > 200 ms (0.20 sec)• QRS Width: < 120 ms (0.12 sec)

1st Degree Heart Block

2nd Degree Heart Block - Type I

• Rate: Identify underlying rate• Rhythm: Regularly-Irregular• P wave: Present• P:QRS ratio: Variable• PR-interval: Variable (going, going, gone…)• QRS Width: < 120 ms (0.12 sec)

2nd Degree Heart Block - Type II

• Rate: Identify underlying rate• Rhythm: Regularly-Irregular• P wave: Present• P:QRS ratio: x:x - 1• PR-interval: Normal *Dropped QRS• QRS Width: < 120 ms (0.12 sec)

3rd Degree Heart Block

• Rate: Atrial & Ventricular rates differ• Rhythm: Regular• P wave: Present• P:QRS ratio: Variable• PR-interval: No pattern• QRS Width: Normal or WIDE

3rd Degree Heart Block

AV Blocks

Interpretation Pearl

• When interpreting an ECG rhythm, always consider the company it keeps. – Associated Signs & Symptoms – Past medical history– Medications…etc

ECG Rhythms

• You must understand the basic ECG arrhythmias prior to moving on.

• Review the previous slides until you think you’ve got it.

• The next slide may assist you if you’re still having a hard time.

The Golden Rule

ECG Interpretation is largely based on THEORY.

Give five cardiologists the same ECG to interpret, and you may receive five different interpretations.

2 rate & rhythms

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