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Simple Diagnosis of Limb‐Lead Reversals by Predictable Changes in QRS Axis
Author(s) -
HO REGINALD T.,
MUKHERJI LENA,
EVANS G. THOMAS
Publication year - 2006
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.2006.00333.x
Subject(s) - medicine , lead (geology) , simple (philosophy) , qrs complex , cardiology , geomorphology , geology , philosophy , epistemology
Background: Limb‐lead reversals (LLRs) remain clinically problematic. Because the frontal QRS axis is derived from an equilateral Einthoven triangle and LLRs either rotate (180 ° horizontally (mirror‐image (M)) and/or 120 ° vertically (clockwise (C)/counterclockwise (CC)) or distort the triangle (by forcing a bipolar lead to record across the lower extremities (LE) where electrical potentials approach zero (zero‐potential lead)), we hypothesize that LLR axes changes from a baseline value (n) are predictable.Methods: Three hundred and sixty ECGs with all 24 limb‐lead combinations from 15 individuals were analyzed. Predicted and actual QRS axes were compared using linear regression.Results: Twenty‐four lead combinations produced only 12 (11 abnormal) ECG patterns and diagnosis depended upon identifying upper extremity (UE) cable configurations. Predicted formulas for rotation‐type LLR axes (M, C, CC, MC, and MCC) were 180 − n, n − 120, n + 120, 300 − n, and 60 − n, respectively. Corresponding mean differences between predicted and actual values were 4 ± 5 °, 4 ± 2 °, 7 ± 10 °, 5 ± 7 °, and 3 ± 4 ° (all r = 0.99 − 1.00, P < 0.0001). The predicted formula for distortion‐type LLR axes is (zero‐potential lead axis) ± 90 °. Actual mean values for zero‐potential lead I, II, and III were 90 ± 7 ° or 266 ± 17 °, −31 ± 6 ° or 148 ± 14 °, and 26 ± 14 ° or 209 ± 9 °, respectively. The mean difference between predicted and actual values for all LLRs was 5 ± 8 ° (r = 1.00, P < 0.0001).Conclusions: LLR axes are predictable within an average of 5 °. This might help differentiate an acute axis shift due to an LLR from serious medical conditions that may require treatment.