Bundle Branch Block and the Imitators of ACS

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MODULE 6
Bundle Branch Block and the Imitators of ACS
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Bundle Branch Block

• Can be pre-existing condition
• Can be caused by ACS

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Bundle Branch Block

• BBB caused by AMI
• 60-70 association with pump failure
• 40-60 mortality without reperfusion

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Bundle Branch Block

• Can mimic ACS
• Can hide evidence of ACS

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Bundle Branch Block

• May Produce
• ST elevation
• ST depression
• Tall T waves
• Inverted T waves
• Wide Q waves

• May Hide
• ST elevation
• ST depression
• Tall T waves
• Inverted T waves
• Wide Q waves

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The Problem

• Critical to reperfuse patients with BBB produced
  by ACS
• ACS harder to identify on ECG when BBB present

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The Solution

• BBB Problem
• New or presumably new BBB is an indication for
  thrombolytic therapy

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The Solution
Fibrinolytic Therapy Trialists (FIT)
Collaborative Group, 1994
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BBB Recognition

• Forget About the Notch!

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BBB Recognition

• Wide QRS
• gt 120ms
• Supraventricular rhythm

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BBB Recognition
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RBBB vs LBBB

• RBBB in V1

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RBBB vs. LBBB

• LBBB in V1

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RBBB vs. LBBB

• Use V1
• Identify direction of terminal force

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Bundle Branch Block

• V1

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BBB Recognition
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BBB Recognition
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BBB
New onset BBB, or presumably new BBB, is an
indication for acute reperfusion therapy
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Ventricular Rhythms

• Paced rhythms
• Idioventricular rhythms
• AIVR
• V-Tach
• PVC

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Ventricular Rhythms

• Can mask or mimic every ECG change suggestive of
  ACS

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Ventricular Rhythms
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Left Ventricular Hypertrophy

• Enlarged left ventricle
• Pumping against increased resistance
• Chronic overfilling

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LVH

• May Produce
• ST elevation
• ST depression
• Tall T waves
• Inverted T waves

• May Hide
• ST elevation
• ST depression
• Tall T waves
• Inverted T waves

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LVH

• Does not abnormally widen QRS
• Increases height and depth of QRS
• Recognized by this increase
• Three step recognition formula

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LVH
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LVH Recognition

• Step 1
• Look in V1 and V2
• Pick the deepest negative deflection
• Count small boxes of negative deflection in that
  lead
• Remember that number

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LVH
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LVH Recognition

• Step 2
• Look in V5 and V6
• Pick the tallest positive deflection
• Count small boxes of positive deflection
• Remember that number

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LVH Recognition

• Step 3
• Add the two numbers together
• Suspect LVH if the sum equals 35 or more

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LVH
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LVH
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Ventricular Aneurysm

• NOT Aortic Aneurysm
• Bleb in ventricle secondary to infarct
• Bleb is dyskinetic
• Pops out when ventricle contracts

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Ventricular Aneurysm
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Ventricular Aneurysm

• Associated with persistent ST elevation
• Often in V1-V4
• Can occur in any lead

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Ventricular Aneurysm
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Benign Early Repolarization
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Benign Early Repolarization

• Normal variant
• Produces
• ST elevation
• Tall T waves

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Benign Early Repolarization

• Changes usually seen in anterior and lateral
  leads
• Most often seen in males ages 20-40
• African-American males

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Benign Early Repolarization

• Look for notch at J-point
• ST segment and J-point create a fish hook
  appearance

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Benign Early Repolarization
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Pericarditis
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Pericarditis

• May be viral, bacterial or metabolic
• Clinical presentation may include chest pain
• Often produces ST elevation on ECG

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Pericarditis

• Clinical presentation
• Sharp chest pain
• Can be localized
• Radiates to base of neck, between shoulder blades

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Pericarditis

• Pain affected by movement and respiration
• Pain improves when patient leans forward
• Pain worsens when patient supine

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Pericarditis

• May produce ST elevation in any lead
• May be in all leads
• May not be anatomically grouped
• J-point notching often present
• Fish hook

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Medications

• Some medications affect the ECG
• Digitalis
• ST depression
• Characteristic sag

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Digitalis Effect
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Summary

• Imitators can produce ST elevation or depression
• Imitators can eliminate ST elevation or depression

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Summary

• Imitators can produce T wave inversion
• Imitators can hide T wave inversion

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Summary

• Imitators can incorrectly place an ECG into any
  of the three categories

ST Elevation BBB
ST Depression T wave inversion
Normal Non-diagnostic
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Summary

• Most frequent imitators
• LVH
• BBB
• Paced rhythms

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Summary

• If the QRS is narrow
• Rules out BBB
• Rules out ventricular rhythms

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Summary

• If QRS is wide
• Consider BBB
• Consider ventricular rhythm

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Summary

• If QRS is narrow
• Consider LVH
• Consider pericarditis
• Consider early repolarization

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Summary

• Fish hooks often seen with
• Pericarditis
• BER
• Fish hooks can also be seen with ACS

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Summary
New BBB, or presumably new BBB, is an indication
for thrombolysis when accompanied by a clinical
presentation suggestive of ACS
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• The presence of an imitator
• DOES NOT rule out an
• Acute Coronary Syndrome