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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?
How does the heart work
PR
AH HV
QRS
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 preexcitation, 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 preexcitation, 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