12 Lead ECGs InjuryInfarct Imposters

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 for appropriate treatment favor one rhythm • CCBs can be very bad in WPW  Identify factors that  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 and depth of QRS  Increases height • 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