12 Lead ECGs: Injury/Infarct Imposters EMS Professions Temple College

Injury/Infarct Imposters b Conditions that make the identification of acute injury/infarction DIFFICULT or IMPOSSIBLE b Some Common Examples (not all inclusive list) Ventricular & Paced RhythmsVentricular & Paced Rhythms LBBBLBBB LVHLVH Benign Early RepolarizationBenign Early Repolarization PericarditisPericarditis

Injury/Infarct Imposters b 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 b Can mask or mimic every ECG change suggestive of ischemia/injury Paced rhythmsPaced rhythms Idioventricular rhythmsIdioventricular rhythms AIVRAIVR V-TachV-Tach PVCsPVCs

Ventricular & Paced Rhythms

Differential Diagnosis of Wide Complex Tachycardias b Necessary for appropriate treatment CCBs can be very bad in WPWCCBs can be very bad in WPW b Identify factors that favor one rhythm b Possibilities: VT, SVT with aberrant conduction, Afib/Aflutter with aberrant conductionVT, SVT with aberrant conduction, Afib/Aflutter with aberrant conduction

Differential Diagnosis of Wide Complex Tachycardias b 1. Ventricular Tachycardia b 2. Ventricular Tach b 3. VT b 4. VT b 5. VT b 6. VT b 7. VT b 8. VT b 9. SVT with preexisting BBB b 10. SVT with aberrant conduction * Ken Grauer. A Practical Guide to ECG Interpretation. 2nd Ed. Top 10 List for WCT*

Differential Diagnosis of Wide Complex Tachycardias b Factors Favoring VT Concordance across all V leads (+/-)Concordance across all V leads (+/-) ERAD axis deviation (“no man’s land”)ERAD axis deviation (“no man’s land”) QRS >.14 secQRS >.14 sec AV dissociationAV dissociation Suggestive QRS morphologySuggestive QRS morphology

Differential Diagnosis of Wide Complex Tachycardias

Left Ventricular Hypertrophy b Enlarged left ventricle Pumping against increased resistancePumping against increased resistance Chronic overfillingChronic overfilling

LVH b May Produce ST elevationST elevation ST depressionST depression Tall T wavesTall T waves Inverted T wavesInverted T waves b May Hide ST elevation ST depression Tall T waves Inverted T waves

LVH b Does not abnormally widen QRS b Increases height and depth of QRS Recognized by this increaseRecognized by this increase Three step recognition formulaThree step recognition formula

LVH

LVH Recognition b Step 1 Look in V1 and V2Look in V1 and V2 Pick the deepest negative deflection (S wave)Pick the deepest negative deflection (S wave) Count small boxes of negative deflection in that leadCount small boxes of negative deflection in that lead Remember that numberRemember that number

LVH Recognition

b Step 2 Look in V5 and V6Look in V5 and V6 Pick the tallest positive deflection (R wave)Pick the tallest positive deflection (R wave) Count small boxes of positive deflectionCount small boxes of positive deflection Remember that numberRemember that number

LVH Recognition

b Step 3 Add the two numbers togetherAdd the two numbers together Suspect LVH if the sum is > 35 (> 35 mm)Suspect LVH if the sum is > 35 (> 35 mm)

LVH Recognition

Benign Early Repolarization

b Normal variant; Difficult to identify b Produces ST elevationST elevation Tall T wavesTall T waves b Changes usually seen in anterior & lateral leads b Most often seen in males ages More common in African-American malesMore common in African-American males Thin, young personsThin, young persons

Benign Early Repolarization Look for notch at J-pointLook for notch at J-point –ST segment and J-point create a “fish hook” appearance

Benign Early Repolarization

Pericarditis

Pericarditis b May be viral, bacterial or metabolic Secondary to recent cardiac surgerySecondary to recent cardiac surgery Post MIPost MI IV Drug abuseIV Drug abuse b Clinical presentation may include CP b Often produces diffuse ST elevation on ECG plus clinical presentation

Pericarditis b Correlate Diffuse ST segment elevation with Clinical Presentation Sharp, “Stabbing” chest painSharp, “Stabbing” chest pain Can be localizedCan be localized May be relieved by movement, respiration, position, swallowingMay be relieved by movement, respiration, position, swallowing May radiate to base of neck, between shoulder bladesMay radiate to base of neck, between shoulder blades

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

Medications b Some medications affect the ECG b Digitalis ST depressionST depression Characteristic sagCharacteristic sag

Medications: Digitalis Effect

Summary b Imitators can produce ST elevation or depression b Imitators can eliminate ST elevation or depression b Most frequent imitators LVHLVH BBBBBB Paced rhythmsPaced rhythms

Summary b If QRS is wide Consider BBBConsider BBB Consider ventricular rhythm (or paced)Consider ventricular rhythm (or paced) b If QRS is narrow Consider LVHConsider LVH Consider pericarditisConsider pericarditis Consider early repolarizationConsider early repolarization

Summary b “Fish hooks” often seen with: PericarditisPericarditis BERBER b “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