title: Signal averaging technique for noninvasive recording of late potentials in patients with coronary artery disease.
abstract: An advanced non invasive signal averaging technique was used to detect late potentials in two groups of patients: Group A (24 patients) with coronary artery disease (CAD) and without sustained ventricular tachycardia (VT) and Group B (8 patients) with CAD and  sustained VT. Recorded analog data were digitized and aligned using a cross correlation function with fast Fourier transform schema, averaged and band pass filtered between 60 and 200 Hz with a non-recursive digital filter. Averaged filtered waveforms were analyzed by computer program for 3 parameters: (1) filtered QRS (fQRS) duration (2) interval between the peak of the R wave peak and the end of fQRS (R-LP) (3) RMS value of last 40 msec of fQRS (RMS).  Significant change was found between Groups A and B in fQRS (101 -/+ 13 msec vs 123 -/+ 15 msec; p < .0005) and in R-LP  vs 52 -/+ 11 msec vs 71-/+18 msec, p <.002). We conclude that (1) the use of a cross correlation triggering method and non-recursive digital filter enables a reliable recording of late potentials from the body surface; (2) fQRS and R-LP durations are sensitive indicators of CAD patients susceptible to VT.
authors.affiliation: Naval Blood Research Laboratory, Boston University School of Medicine, USA.
authors.forename: S
authors.initials: S
authors.lastname: Abboud
authors.forename: C M
authors.initials: CM
authors.lastname: Blatt
authors.forename: B
authors.initials: B
authors.lastname: Lown
authors.forename: T B
authors.initials: TB
authors.lastname: Graboys
authors.forename: D
authors.initials: D
authors.lastname: Sadeh
authors.forename: R J
authors.initials: RJ
authors.lastname: Cohen
mesh_terms: D000465:Algorithms; D003327:Coronary Disease / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods; D005069:Evaluation Studies as Topic; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D012815:Signal Processing, Computer-Assisted; D017180:Tachycardia, Ventricular / Q000503:physiopathology*; D014693:Ventricular Fibrillation / Q000503:physiopathology*