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Line 1: |
| ==Cardiac Ischemia== | | ==ACS== |
| ===T Wave===
| | *See [[ACS - ECG]] |
| *Distribution
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| **T wave is normally inverted in aVR; sometimes inverted in III, aVF, aVL, V1
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| *T-wave inversions in V2-V6 are pathologic
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| *Morphology
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| **Inverted, symmetric,
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| **Transient changes suggests ischemia without infarction
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| **Persistent changes suggests infarction (troponin elevation usually seen)
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| *Pseudonormalization
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| **In presence of baseline TWI (within 1 month), reocclusion causes normalization of TWI
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| **Should be interpreted as evidence of ischemia
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| ===Q Wave===
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| *Q waves do not always indicate infarction (see DDX below)
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| *Must distinguish normal septal q waves from pathologic Q waves:
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| **Normal septal q wave: <0.04s, low amplitude
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| **Abnormal septal q wave: >0.04s in I OR in II, III, AND aVF OR V3, V4, V5, AND V6
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| *Q-wave equivalents in the precordial leads:
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| **R-wave diminution or poor R-wave progression
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| **Reverse R-wave progression (R waves increase then decrease in amplitude)
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| ***Must distinguish from lead misplacement
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| **Tall R waves in V1, V2 (representing "Q waves" from posterior infarction)
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| ====Q Wave (Pathologic) DDX====
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| *Ischemic Q waves
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| *LBBB
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| *LVH
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| *Chronic lung disease
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| *Hypertrophic cardiomyopathy
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| *Dilated cardiomyopathy
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| ===ST Segment Depression===
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| *Assume posterior STEMI or reciprocal changes to STEMI until proven otherwise
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| *Indicators of ischemia:
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| **>0.5mm depression from baseline (especially >1mm) in two or more contiguous leads
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| **Transient depression
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| **Morphology that is flat or downsloping
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| ===ST Segment Elevation===
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| *Stage 1
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| **Timing: 30min - hours
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| **Finding: hyperacute T waves
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| ***>6mm limb leads
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| ***>10mm precordial leads
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| **Duration: normalizes in days, weeks, or months
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| *Stage 2
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| **Timing: minutes - hours | |
| **Finding: ST segment elevation
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| ***≥0.1mV in two or more contiguous leads
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| **Duration: ST segment resolution occurs over 72hrs; completely resolves w/in 2-3wks
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| *Stage 3
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| **Timing: within 1hr; completed within 8-12hr
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| **Finding: Q waves
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| **Duration: persist indefinitely in 70% of cases
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| ===Reciprocal Changes===
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| #Anterior STEMI
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| ##Reciprocal ST-segment depression in at least one of leads II, III, aVF
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| ##Occurs in 40-70% of cases
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| #Inferior STEMI
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| ##Reciprocal ST-segment depression usually present in I, aVL; often in V1-V3
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| ##Occurs in 56% of cases
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| #Posterior STEMI
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| ##Reciprocal ST-segment depression in V1-V4
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| ###Differentiate from inf STEMI reciprocal depression based on upright T waves, posterior leads showing STEMI
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| ##Often associated w/ ST-segment elevation in II, III, aVF (inferior involvement)
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| ==Anatomical Correlation==
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| #Posterior
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| ##ST depression in V1-V2
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| ##R-S ratio of >1 in V1 or V2
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| ##ST elevation >1 in V7-9
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| ##Often accompanied by inferior ST changes
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| ##Often accompanied by RV MI
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| #Anterior
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| ##ST depression in II, III, aVF usually due to high lateral ST elevation (I, aVL)
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| #Inferior
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| ##Look at I, aVL for reciprocal changes (ST depression or TWI)
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| ###If no changes pt probably not having an inf STEMI
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| ==Aneurysm== | | ==Aneurysm== |
| Line 114: |
Line 36: |
| *[[ST Segment Elevation]] | | *[[ST Segment Elevation]] |
| *[[ST Segment Depression]] | | *[[ST Segment Depression]] |
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| ==Source==
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| *Electrocardiography in Emergency Medicine. ACEP Textbook.
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| [[Category:Cards]] | | [[Category:Cards]] |
