title: On the variability of QRS time-duration in magnetocardiographic recordings.
abstract: High resolution electrocardiography (HRECG) recordings have already shown an increased beat-to-beat microvariability of the QRS duration of the terminal QRS in patients with a history of ventricular tachycardia (VT). The purpose of this study is to detect QRS-duration microvariability with magnetocardiographic (MCG) recordings in normals, patients with coronary heart disease (CHD), patients with a history of myocardial infarction (MI), and VT patients. QRS microvariability is calculated as the variance of time-shifts of single beats respectively to the average of all beats. The average over all channels of the MCG is performed. QRS microvariability was evaluated from 55-channel MCG in 15 normal persons, in 12 patients with CHD, in 13 patients with MI, and in 10 patients with VT. We found a significantly higher microvariability in patients with MI compared to normals. The highest microvariability was found in VT patients.
authors.affiliation: Department of Cardiology, University of Ulm, D-89081 Ulm Germany.
authors.forename: B G
authors.initials: BG
authors.lastname: Schless
authors.forename: H-P
authors.initials: HP
authors.lastname: Müller
authors.forename: A
authors.initials: A
authors.lastname: Pasquarelli
authors.forename: S N
authors.initials: SN
authors.lastname: Erné
authors.forename: V
authors.initials: V
authors.lastname: Hombach
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D003327:Coronary Disease / Q000175:diagnosis / Q000503:physiopathology*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D015233:Models, Statistical; D009203:Myocardial Infarction / Q000175:diagnosis / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology*