12 Lead ECGs: Injury/Infarct Imposters
EMS Professions Temple College
Injury/Infarct Imposters
Conditions that make the identification of acute injury/infarction DIFFICULT or IMPOSSIBLE Some Common Examples (not all inclusive list)
• • • • •
Ventricular & Paced Rhythms LBBB LVH Benign Early Repolarization Pericarditis
Injury/Infarct Imposters
Imposters can incorrectly place an ECG into any of the three categories
ST Elevation BBB
ST Depression T wave inversion
Normal Non-diagnostic
Ventricular & Paced Rhythms
Can
mask or mimic every ECG change suggestive of ischemia/injury
• • • • • Paced rhythms Idioventricular rhythms AIVR V-Tach PVCs
Ventricular & Paced Rhythms
Differential Diagnosis of Wide Complex Tachycardias
Necessary
Identify
for appropriate treatment
• CCBs can be very bad in WPW
factors that favor one rhythm Possibilities:
• VT, SVT with aberrant conduction, Afib/Aflutter with aberrant conduction
Differential Diagnosis of Wide Complex Tachycardias
Top 10 List for WCT*
1. Ventricular Tachycardia 2. Ventricular Tach 3. VT 4. VT 5. VT
6. VT 7. VT 8. VT 9. SVT with preexisting BBB 10. SVT with aberrant conduction
* Ken Grauer. A Practical Guide to ECG Interpretation. 2nd Ed.
Differential Diagnosis of Wide Complex Tachycardias
Factors
Favoring VT
• • • • •
Concordance across all V leads (+/-) ERAD axis deviation (“no man’s land”) QRS > .14 sec AV dissociation Suggestive QRS morphology
Differential Diagnosis of Wide Complex Tachycardias
Differential Diagnosis of Wide Complex Tachycardias
Left Ventricular Hypertrophy
Enlarged
left ventricle
• Pumping against increased resistance • Chronic overfilling
LVH
May
Produce
May
Hide
• • • •
ST elevation ST depression Tall T waves Inverted T waves
• • • •
ST elevation ST depression Tall T waves Inverted T waves
LVH
Does
not abnormally widen QRS height and depth of QRS
Increases
• Recognized by this increase • Three step recognition formula
LVH
LVH Recognition
Step
1
• Look in V1 and V2 • Pick the deepest negative deflection (S wave) • Count small boxes of negative deflection in that lead • Remember that number
LVH Recognition
LVH Recognition
Step
2
• Look in V5 and V6 • Pick the tallest positive deflection (R wave) • Count small boxes of positive deflection • Remember that number
LVH Recognition
LVH Recognition
Step
3
• Add the two numbers together • Suspect LVH if the sum is > 35 (> 35 mm)
LVH Recognition
LVH Recognition
Benign Early Repolarization
Benign Early Repolarization
Normal
variant; Difficult to identify Produces
• ST elevation • Tall T waves
usually seen in anterior & lateral leads Most often seen in males ages 20-40
• More common in African-American males • Thin, young persons
Changes
Benign Early Repolarization
• Look for notch at J-point
– ST segment and J-point create a “fish hook” appearance
Benign Early Repolarization
Pericarditis
Pericarditis
May
be viral, bacterial or metabolic
• Secondary to recent cardiac surgery • Post MI • IV Drug abuse
Clinical
presentation may include CP Often produces diffuse ST elevation on ECG plus clinical presentation
Pericarditis
Correlate
Diffuse ST segment elevation with Clinical Presentation
• Sharp, “Stabbing” chest pain • Can be localized • May be relieved by movement, respiration, position, swallowing • May radiate to base of neck, between shoulder blades
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
Medications
Some
medications affect the
ECG Digitalis
• ST depression • Characteristic sag
Medications: Digitalis Effect
Summary
Imitators
can produce ST elevation or depression Imitators can eliminate ST elevation or depression Most frequent imitators
• LVH • BBB • Paced rhythms
Summary
If
QRS is wide
• Consider BBB • Consider ventricular rhythm (or paced)
If
QRS is narrow
• Consider LVH • Consider pericarditis • Consider early repolarization
Summary
“Fish
hooks” often seen with:
• Pericarditis • BER
“Fish
hooks” can also be seen with ACS
Summary
The presence of a potential imposter DOES NOT ALWAYS make it impossible to identify injury/infarction