Systematic approach for 12 lead ECG Flashcards
Define ST elevation
- Measure how much higher the J point is from the isoelectric line (S wave not present in STEMI)
- 1mm ST elevation in 2 contigous leads except V2-3
- V2-3 requires at least 2mm ST elevation
What is ddx of ST elevation?
- STEMI
- Benign early repolarization
- Pericarditis
- Vasospasm
- Pulmonary embolism
- LV aneurysm
- LV hypertrophy
- LBBB
Define ST depression
- Need 0.5mm ST depression in 2 contigous leads
- Horizontal ST depression is most concerning for ischemia
- However upsloping ST depression with peaked T waves in V1-V3 is concerning for LAD occlusion
What is the ddx of ST depression?
- NSTEMI
- Posterior MI
- LBBB
- LVH w/strain
- Reciprocal changes
- Digoxin toxicity (classic U shape)
Define J wave
No S wave (has to go down through the isoelectric line than go back up)
* After R wave there is a J wave (positive deflection) creating a fish hook appearance
* Helpful to differentiate benign early repolarization vs STEMI
What is ddx of J wave?
- Benign early repolarization
- Hypothermia
- Hypercalcemia
- Brugada syndrome
Define T wave inversion
ddx
If T wave inversion in aVL only –> serial ECG as there is suspicion of inferior MI
Wellens B: proximal LAD ischemia (biphasic or deeply inverted T waves in V2-3)
Define hyperacute T wave
Ddx?
If flat T wave think early STEMI
Define biphasic T wave
ddx
Worry if see biphasic T wave in V2-V3 as this fulfils Wellens A criteria (proximal LAD ischemia): upward curve than downward curve
If downward curve than upward curve think hyperK
Define flat T wave
ddx
Sign of impending ischemia
Define peaked T waves
What is ddx
If peaked T waves and upsloping ST depression in V1-3 worry about proximal LAD occlusion (De Winters T waves)
Define wide QRS
ddx
Define pathological Q wave
ddx
Never seen in V1-V3
Pathological Q wave
* >0.04s
* >2mm in depth
* or 25% of QRS depth
ddx
* MI (old or new)
* PE
* LBBB
* LVH
Define low voltage qrs
ddx
Definition
* no QRS complex with an absolute value 10mm
* Or, no limb lead QRS 5mm (low voltage in limb leads)
ddx
Dcreased voltage production by myocardium: restrictive cardiomyopathies (amyloidosis, sarcidosis), hypothyroidism
Increased impendence between the voltage producing source (myocardium) and the ECG leads
* Fat (obesity)
* Air (COPD, tension pneumothorax)
* Water (pericardial or pleural effusion, ascites)
Define poor R wave progression
ddx
Define dominant R wave
What is ddx
Dominant R waves, ST depression and upright T waves in V1-3 think posterior MI
Rule out RBBB and RVH as well
What leads to look at and criteria for LVH?
What leads to look at and criteria for RVH?
Define prolonge QTi
What is ddx
Risk of progressing to what condition
What leads to determine right atrial enlargement?
What is ddx?
ddx
* Tricuspid stenosis
* Pulmonary hypertension
* Pulmonic stenosis
What leads to determine left atrial enlargement?
What is ddx?
ddx
* Mitral stenosis
* Hypertension
* Aortic stenosis
Define shortened PR interval
Causes?
PAC: look for shortened R-R intervals (which will also have shortened PRi)
Define prolonged PR interval?
ddx?
What leads to assess normal axis?
Lead I positive
Lead aVF positive. If negative need to check lead II to confirm.
If lead II is positive –> than normal axis
What leads to assess in left axis deviation?
What is ddx?
Whenever lead I +ve and lead aVF -ve –> need to check lead II to confirm. If lead II is also -ve than it is left axis deviation.
What leads and result to assess right axis deviation?
ddx?
What leads and result to assess extreme right axis deviation?
ddx?
Lead I and lead aVF
