CardioNerds ECG Challenge #4

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56 year-old woman presents to the local ED frightened.  She has a history of anxiety and is on no medications.​
Interpret this EKG


1. Sinus tachycardia at 107/min​
2. Incorrect electrode placement, specifically RA/LA transposition​
3. Otherwise normal EKG

Learning Points:​

Fright accounts for her sinus tachycardia. With RA/LA transposition lead I is inverted, lead II looks like lead III, aVR like aVL, aVL like aVR, aVF and V1-V6 are unchanged. This arm lead transposition does not account for QRS voltage in V3-V6 which is due to breast attenuation. The R/S ratio increasing from V1-V6 is one clue that this is not dextrocardia.

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