To the Editor In a recent issue of JAMA Internal Medicine, Abou Ziki and Rosenfeld1 published an elegant study demonstrating how meticulous analysis of the effects of premature atrial complexes on the initiation and termination of a repetitive supraventricular tachycardia helped decipher its electrophysiologic mechanism.
I would like to raise awareness to the fact that in one of the electrocardiograms (ECGs), limb leads were almost certainly reversed. The telltale signs are more obvious when Figure 2A1 is enlarged. In that ECG, the signals in lead II are of very low amplitude, almost a flat line. Flat line in lead II is a typical finding in right arm and right leg lead reversal because when the right arm lead is placed to the right leg, lead II records the potential difference between the 2 feet which is close to 0.2,3 Lead reversal in this ECG is further supported by the presence of positive “retrograde” P waves in leads III and aVF and negative P waves in aVL (see the arrowheads in Figure 2A1). In AV nodal reentrant supraventricular tachycardia, retrograde P waves are always negative in the inferior leads and are usually positive in aVL.4
Littmann L. Beware of Limb Lead Reversal. JAMA Intern Med. 2018;178(3):435. doi:10.1001/jamainternmed.2017.8636
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