title: Inter-lead correlation analysis for automated detection of cable reversals in 12/16-lead ECG.
abstract: OBJECTIVE
  A crucial factor for proper electrocardiogram (ECG) interpretation is the correct electrode placement in standard 12-lead ECG and extended 16-lead ECG for accurate diagnosis of acute myocardial infarctions. In the context of optimal patient care, we present and evaluate a new method for automated detection of reversals in peripheral and precordial (standard, right and posterior) leads, based on simple rules with inter-lead correlation dependencies.
  
  
  METHODS
  The algorithm for analysis of cable reversals relies on scoring of inter-lead correlations estimated over 4s snapshots with time-coherent data from multiple ECG leads. Peripheral cable reversals are detected by assessment of nine correlation coefficients, comparing V6 to limb leads: (I, II, III, -I, -II, -III, -aVR, -aVL, -aVF). Precordial lead reversals are detected by analysis of the ECG pattern cross-correlation progression within lead sets (V1-V6), (V4R, V3R, V3, V4), and (V4, V5, V6, V8, V9). Disturbed progression identifies the swapped leads.
  
  
  RESULTS
  A test-set, including 2239 ECGs from three independent sources-public 12-lead (PTB, CSE) and proprietary 16-lead (Basel University Hospital) databases-is used for algorithm validation, reporting specificity (Sp) and sensitivity (Se) as true negative and true positive detection of simulated lead swaps. Reversals of limb leads are detected with Se = 95.5-96.9% and 100% when right leg is involved in the reversal. Among all 15 possible pairwise reversals in standard precordial leads, adjacent lead reversals are detected with Se = 93.8% (V5-V6), 95.6% (V2-V3), 95.9% (V3-V4), 97.1% (V1-V2), and 97.8% (V4-V5), increasing to 97.8-99.8% for reversals of anatomically more distant electrodes. The pairwise reversals in the four extra precordial leads are detected with Se = 74.7% (right-sided V4R-V3R), 91.4% (posterior V8-V9), 93.7% (V4R-V9), and 97.7% (V4R-V8, V3R-V9, V3R-V8). Higher true negative rate is achieved with Sp > 99% (standard 12-lead ECG), 81.9% (V4R-V3R), 91.4% (V8-V9), and 100% (V4R-V9, V4R-V8, V3R-V9, V3R-V8), which is reasonable considering the low prevalence of lead swaps in clinical environment.
  
  
  CONCLUSIONS
  Inter-lead correlation analysis is able to provide robust detection of cable reversals in standard 12-lead ECG, effectively extended to 16-lead ECG applications that have not previously been addressed.
authors.affiliation: Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria. Electronic address: irena@biomed.bas.bg.
authors.forename: Irena
authors.initials: I
authors.lastname: Jekova
authors.affiliation: Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors.forename: Vessela
authors.initials: V
authors.lastname: Krasteva
authors.affiliation: Biomed Research and Signal Processing, Schiller AG, Baar, Switzerland.
authors.forename: Remo
authors.initials: R
authors.lastname: Leber
authors.affiliation: Biomed Research and Signal Processing, Schiller AG, Baar, Switzerland.
authors.forename: Ramun
authors.initials: R
authors.lastname: Schmid
authors.affiliation: Cardiovascular Research Institute Basel, University Hospital Basel, Basel, Switzerland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Twerenbold
authors.affiliation: Cardiovascular Research Institute Basel, University Hospital Basel, Basel, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Müller
authors.affiliation: Cardiovascular Research Institute Basel, University Hospital Basel, Basel, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Reichlin
authors.affiliation: Biomed Research and Signal Processing, Schiller AG, Baar, Switzerland; Cardiovascular Research Institute Basel, University Hospital Basel, Basel, Switzerland.
authors.forename: Roger
authors.initials: R
authors.lastname: Abächerli
mesh_terms: D000465:Algorithms; D001331:Automation; D004562:Electrocardiography / Q000295:instrumentation*
keywords: Cross-correlation analysis; ECG electrode interchange; ECG pattern progression; Lead swap; Limb leads; Precordial leads