ECG Tutorial: Rhythm Recognition

• Review – the systematic approach

• Rhythm – the hardest part!– Again – be systematic– Mind your p’s & q’s & follow the rules!

• The Approach – Tachy –vs- Brady

• Examples

• Quiz

ECG Tutorial: Rhythm Recognition

• My systematic approach:– Rate

– Rhythm– Axis– Intervals (PR, QRS, QTc)– Blocks / Hypertrophy / Enlargement– Segments (PR, ST)– Waves (Q-waves, T-waves)– Ectopy– Compare to old ECG

Rhythm Recognition

• Golden rule: mind your ‘p’s (& ‘q’s’)• Step I – Is it fast or slow?

– Tachycardia = >100

– Bradycardia = < 60

• Step II – Is it sinus rhythm or not?– 2 questions (rules):

• ‘p’ with every QRS complex?

• Upright ‘p’ in I, II & aVF?

– Yes to BOTH = sinus origin (nice job!)

Rhythm : Is there a p wave? = Sinus

Is it followed by a QRS?

PR QRS

AH HV

How does the heart work

Is the rhythm regular or irregular?

Tachycardias: The ‘Down & Dirty’

• Common• Need to recognize the ‘bad boys’!

– ACLS, etc…

• 2 questions– Is the QRS narrow (<=0.12 second or 2.5 small boxes)

or wide? • “Wide complex Tachycardia”-vs-“Narrow Complex

Tachycardia”

– Is the rhythm regular or irregular?

Normal Sinus Rhythm; Rate = 75

Sinus Arrythmia-Typically a normal finding – esp. in younger, fit individuals

-Due to changes in autonomic tone during inspiration

Tachycardias: DDx(Rule of 3’s!)

• Narrow Complex & Regular:– Sinus Tachycardia– Atrial Flutter– Other supraventricular Tachycardia (SVT)

• AVNRT (A-V nodal reentrant tachycardias)• Atrial reciprocating tachycardia (from pre-

excitation, ex: WPW)• Ectopic atrial tachycardia• Other uncommon causes

Sinus Tachycardia…but why?

• Physiologic (#1)– Response to exercise

– Stress, anger, etc.. (‘fight or flight’)

• Other causes:– Fever– Hyperthyroidism– Effective volume depletion,

hypotension– Sepsis, Shock– Anemia– PE– CHF– Drugs (stimulants)– Drug withdrawal (ETOH)– Pheochromocytoma

Atrial Flutter – characteristics?

Atrial Flutter – characteristics?

Suspect A-flutter:•Narrow complex tachycardia

•‘F’ (flutter waves) = rate of 300 (“sawtooth”)

•Ventricular rate = 150 bpm

Atrial Flutter – what is happening in the heart!

Other Narrow Complex Tachycardiaa - AVNRT

NSR Premature Atrial Complex (PAC)

-Regular, Narrow-complex tachycardia w/rate: 120-220

-‘p’ buried or after QRS (usually) & inverted (retrograde) in leads I, II & aVF

-Most common non-fib/flutter SVT

AVNRT

Ectopic Atrial Tachycardia

• Regular narrow complex tachycardia

• Originates outside of the AV node

• Constant ‘p’ wave morphology

• Constant P-R intervals

• Use the “rule of sinus rhythm” & mind your ‘p’s’

Ectopic atrial tachycardia

Ectopic atrial tachycardia:Can occur with block

(ie-digoxin toxicity)

Tachycardias: DDx

• Narrow Complex & IR-regular:– Atrial Fibrillation (“irregularly irregular”)– Atrial Flutter with variable A-V block– MAT (Multifocal Atrial Tachycardia)– Other Supraventricular tachycardias with

variable AV block

•

Atrial Fibrillation

• The most common arrythmia in older patients• ECG:

– Absent ‘p’-waves

– “fibrillatory waves” – vary in appearance

– Irregularly irregular R-R intervals

– Typically narrow complex QRS (unless aberrant conduction)

• Bundle Branch Blocks / other blocks

• Re-entry (WPW)

– Rate > 100 = “rapid ventricular response” (RVR)

Remember this?

A-flutter with variable AV-block

MAT – Multifocal Atrial Tachycardia

• Narrow complex, irregularly irregular• You’re thinking A-fib, but…

– You see clearly conducted ‘p’-waves– ‘p’-waves are not all the same

• You see 3 different ‘p’-wave morphologies • “Multifocal”• Varying P-P & R-R intervals

– Associated with lung disease (COPD), theophylline, hypertension, etc…

MAT

Narrow Complex Tachycardias - Review

• Regular:– Sinus Tachycardia– Atrial Flutter– Other “SVT”

• AVNRT (A-V nodal reentrant tachycardias)

• Atrial reciprocating tachycardia (from pre-excitation, ex: WPW)

• Ectopic atrial tachycardia

• Others (uncommon)

• IR-regular:– Atrial Fibrillation

(“irregularly irregular”)– Atrial Flutter with

variable A-V block

– MAT (Multifocal Atrial Tachycardia)

– Others

Doctor…come quick!

Wide Complex Tachycardias (WCT)

• A Big Deal…may require emergent treatment!• A limited Differential Diagnosis

– Ventricular Tachycardia (VT)– NOT Ventricular Tachycardia:

• SVT w/aberrant conduction (Aberrancy)• SVT w/pre-excitation (ie-WPW)

– What is “aberrancy”?

• Assume Ventricular Tachycardia until proven otherwise– Esp. in a patient over 40 years old

Doctor, hurry up & read that EKG…

Wide Complex Tachycardia

• Rate > 100 bpm

• QRS duration > 0.12 seconds

• Again– Regular –vs- Irregular

Wide Complex Tachycardia

• Regular– Ventricular Tachycardia– A REGULAR SVT w/Aberrant conduction

• Sinus tachycardia

• A-flutter

• AVNRT

• Atrial Tachycardia

Wide Complex Tachycardia

• IR-Regular– Ventricular Fibrillation– An IR-Regular SVT w/Aberrant conduction

• Atrial fibrillation

• Aflutter with variable AV block

• MAT

– Special Case: WPW & A-fib

V-Tach –vs- SVT w/Aberrancy

• Assume V-T until proven otherwise– Treatment for SVT can kill a patient in VT– Treatment for VT usually won’t kill a patient in

SVT– Criteria – Brugada, others (beyond our scope)

• AV dissociation, increased age, CV risk factors = VT

• Fusion / Dresler beats = VT

Wide, Fast & Irregularly, Irregular = WPW (usually)

Special Treatment

This patients resting EKG after you cardiovert him…

Bradyarrythmias

• I. Pauses– #1 cause of a pause is a non-conducted PAC

• II. Early, weird-looking beats: PVC –vs- PAC– PVC

• Wide complex• Compensatory pause

– PAC• Narrow, no compensatory pause

Bradyarrythmias

• I. Problem is sinus or at the AV node– Sinus:

• Sinus bradycardia• Sinus Arrest

– AV Node:• 1st Degree AV block• 2nd Degree

– Mobitz I (Wenkebach)– Mobitz II

• 3rd Degree AVB

2nd degree Mobitz I (Wenkebach)

-lengthening PR interval…then…dropped beat

-“Group Beating” = Wenkeback until proven otherwise

-Block at AV node

-Normal in young patients (high vagal tone)

-Think Meds (B-blockers, CCBs)

2nd degree Mobitz II-Constant PR interval…then dropped beat

-Block always BELOW AV node (more serious)

-Never normal

-Likely needs a pacemaker

3rd degree (complete) heart block

-A-V dissociation is present

-‘p’ waves “march” out

-Atrial rate > ventricular rate**

-“Escape” rhythm

-Clinical settings

-Likely needs a pacemaker

Summary

• Follow the rules – be systematic– Tachycardia

• Narrow or Wide

• Regular or Irregular

– Bradycardia• Mind your ‘p’s’• Know the basics

• Questions• Now, let’s do some examples