Causes of ST-segment elevation
- Acute myocardial injury (ACO or trauma)
- Global ischemia (e.g. Epi, dissection, massive GI bleeding, etc.)
- Vasospasm
- Early Repolarization
- Myo/pericarditis
- Ventricular aneurysm
- LVH/high left ventricular voltage
- LBBB/pacemaker
- Pulmonary embolism
- Hyperkalemia
- Na+channelopathy (e.g. Brugada syndrome & mimics, TCA’s, etc.)
- Hypothermia
- Post-cardioversion (stunning)
- Takotsubo cardiomyopathy
- Intracranial abnormalities
- “Spiked Helmet” sign
- Hypercalcemia
ECG findings in Hyperkalemia
- Peaked T-waves (even when inverted)
- Widening of the QRS (often marked)
- Prolonged PR-interval
- Flattening and eventual loss of P-waves
- Bizarre tachydysrhythmias, pseudo ventricular tachycardia
- Bizarre bradydysrhythmias, advanced AV Blocks and sinus pauses
- Axis changes (especially RAD)
- Fascicular & Bundle Branch Blocks
- Pseudo ACS with ST-segment changes (can mimic STEMI)
- Pseudo Brugada syndrome pattern
- Sine wave morphology
Causes of Rightward Axis Deviation
- Ventricular ectopy
- Right ventricular hypertrophy
- Left posterior fascicular block
- Lateral MI (from Q-waves in lead I)
- Na+channel blocker toxicity
- Hyperkalemia
- Pulmonary HTN – Acute (PE) & chronic lung disease (COPD)
- Lead misplacement / Dextrocardia
- Normal variant in young kids & thin adults with horizontally positioned hearts
Causes of Rightward Axis + ST-segment elevation mimicking STEMI (which usually does not produce rightward axis)
- Hyperkalemia
- Na+channel blocker toxicity
- Pulmonary HTN – Acute (PE) & chronic lung disease (COPD)
Final take-home points:
- Beware hyperkalemia!!
- Peaked T’s
- Widening of QRS
- Prolonged PR
- Flattening and eventual loss of P’s
- Tachycardias
- Bradycardias, AV blocks and sinus pauses
- Pseudo-ACS, new BBB’s, ST changes
- Sine wave
- STE common in V1-V2, and aVR in hyperkalemia
- Large PE’s can often mimic STEMI with ST-segment elevation (especially in rightward leads)
- STEMI’s don’t tend to produce a rightward axis
- Rightward axis in apparent “STEMI”? Pay attention to the axis and consider large PE and hyperkalemia!
