Baylor University Medical Center Proceedings April 2014, Volume 27, Number 2 | Page 50

Inverted P waves, QRS complexes, and T waves in lead I in a 64-year-old woman D. Luke Glancy, MD, and Davey L. Prout Jr., MD he combination of inverted Ps, QRSs, and Ts in lead I (Figure 1) suggests two possibilities: arm-lead reversal and situs inversus with mirror-image dextrocardia. The standard precordial leads usually settle the issue; they are normal in arm-lead reversal and show diminishing QRS voltage from V1 to V6, usually with dominant S waves, in situs inversus. This electrocardiogram (ECG), however, fits neither description. The precordial leads show a reverse of the usual progression. Lead V1 resembles the usual lead V6, V2 resembles the usual V5, and so forth, with V6 resembling the usual V1. Thus, the precordial leads also have been reversed. When the arm leads are reversed, lead I is an inversion of the true lead I; lead II is the true lead III; lead III is the true lead II; aVR is the true aVL; aVL is the true aVR; and aVF is unchanged. With these caveats and the reversed sequence of V1 to V6 in mind, this ECG is normal. An ECG recorded 12 days later (Figure 2) indeed is normal and resembles all of the ECGs recorded in this patient before the one shown in Figure 1. The bane of the electrocardiographer is the misinformation provided by artifacts, lead misplacement, and labeling the ECG with the wrong name (1). Most lead misplacement is not intentional. When it is intentional, such as recording the chest leads on the right side looking for evidence of right ventricular infarction in a patient with an acute inferior infarct, this should be stated clearly on the tracing. T 1. 124 Figure 1. ECG in a 64-year-old woman. Figure 2. ECG in the same woman 12 days later. Surawicz B, Knilans TK. Misplacement of leads and electrocardiographic artifacts. In Surawicz B, Knilans TK, eds. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric, 5th ed. Philadelphia: WB Saunders, 2001:569–582. From the Sections of Cardiology, Departments of Medicine, Louisiana State University Health Sciences Center and the Interim LSU Hospital, New Orleans, Louisiana. Corresponding author: D. Luke Glancy, MD, 7300 Lakeshore Drive, #30, New Orleans, LA 70124 (e-mail: [email protected]). Proc (Bayl Univ Med Cent) 2014;27(2):124