Document Detail

Simple diagnosis of limb-lead reversals by predictable changes in QRS axis.
MedLine Citation:
PMID:  16606394     Owner:  NLM     Status:  MEDLINE    
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 degrees horizontally (mirror-image (M)) and/or 120 degrees 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 degrees , 4 +/- 2 degrees , 7 +/- 10 degrees , 5 +/- 7 degrees , and 3 +/- 4 degrees (all r = 0.99 - 1.00, P < 0.0001). The predicted formula for distortion-type LLR axes is (zero-potential lead axis) +/- 90 degrees . Actual mean values for zero-potential lead I, II, and III were 90 +/- 7 degrees or 266 +/- 17 degrees , -31 +/- 6 degrees or 148 +/- 14 degrees , and 26 +/- 14 degrees or 209 +/- 9 degrees , respectively. The mean difference between predicted and actual values for all LLRs was 5 +/- 8 degrees (r = 1.00, P < 0.0001). CONCLUSIONS: LLR axes are predictable within an average of 5 degrees . This might help differentiate an acute axis shift due to an LLR from serious medical conditions that may require treatment.
Reginald T Ho; Lena Mukherji; G Thomas Evans
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Pacing and clinical electrophysiology : PACE     Volume:  29     ISSN:  0147-8389     ISO Abbreviation:  Pacing Clin Electrophysiol     Publication Date:  2006 Mar 
Date Detail:
Created Date:  2006-04-11     Completed Date:  2006-09-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7803944     Medline TA:  Pacing Clin Electrophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  272-7     Citation Subset:  IM    
Department of Medicine, Division of Cardiology, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania 19107, USA.
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MeSH Terms
Body Surface Potential Mapping / methods*
Diagnostic Errors / prevention & control*
Electrocardiography / instrumentation*,  methods*
Reproducibility of Results
Sensitivity and Specificity

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