title: Abnormal signal averaged ECG after surgical repair of tetralogy of Fallot--a combined analysis in the time and frequency domain.
abstract: OBJECTIVE
  The clinical significance of abnormal signal averaged ECG (SA-ECG) determined by time and frequency domain analyses was assessed in tetralogy of Fallot patients after surgical repair, and the methods of analysis were compared.
  
  
  METHODS
  SA-ECG was performed in 42 patients (mean age, 9.4 years) after radical surgical repair of tetralogy of Fallot, and in 11 preoperative patients (mean age, 2.6 years). Abnormal SA-ECGs were defined by time domain analysis (vector magnitude method) and frequency domain analysis (fast Fourier transformation).
  
  
  RESULTS
  Abnormal SA-ECGs were recognized in 10 postoperative, patients (3 by time domain and 9 by frequency domain, analysis), but in none of the preoperative patients. Three patients with abnormal SA-ECGs had nonsustained ventricular tachycardia, 5 others had premature ventricular contractions, and the remaining 2 had no ventricular tachyarrhythmias documented by 24 h Holter monitoring. Patients with abnormal SA-ECGs more commonly had ST-T segment depression on standard ECG during exercise (8/10 versus 8/32, p < 0.001), a history of resection of a hypertrophic septoparietal muscle band (8/10 versus 2/32, p < 0.001) and histologically documented myocardial fibrosis at radical surgical repair (9/10 versus 5/19, p < 0.002).
  
  
  CONCLUSIONS
  A Combination of time and frequency domain analyses was necessary to detect abnormal SA-ECGs in postoperative patients because of ventricular conduction disturbance. This technique might increase our ability to identify patients at risk of ventricular tachyarrhythmia, or those with underlying myocardial abnormalities.
authors.affiliation: Department of Pediatrics, Tokushima University Hospital, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Matsuoka
authors.forename: H
authors.initials: H
authors.lastname: Akita
authors.forename: Y
authors.initials: Y
authors.lastname: Hayabuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Taguchi
authors.forename: M
authors.initials: M
authors.lastname: Kubo
authors.forename: T
authors.initials: T
authors.lastname: Kitagawa
authors.forename: I
authors.initials: I
authors.lastname: Katoh
authors.forename: K
authors.initials: K
authors.lastname: Ii
mesh_terms: D000293:Adolescent; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000503:physiopathology; D005117:Cardiac Complexes, Premature / Q000209:etiology / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods; D005583:Fourier Analysis; D006801:Humans; D009206:Myocardium / Q000473:pathology; D011183:Postoperative Complications / Q000503:physiopathology; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000503:physiopathology; D013771:Tetralogy of Fallot / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*