Submitted: Ms. M. Codispoti MUHC 1999 The right and left arm leads have been reversed in the top tracing. Note the negative P wave in I which suggests that this is not a form of dextrocardia. Note that the precordial leads are unchanged by this error, which also excludes dextrocardia. Note that aVF changes little, aVL switches with aVR, II switches with III.	Rate (/min)	63	QT (ms)	410
	pr (ms)	150	QRS axis (degrees)	155
	QRS (ms)	94

This is probably the most common lead reversal. The right arm lead has been switched with the left arm. Note the negative P wave in lead I that argues against dextrocardia.