title: Characterization of repolarization alternans during ischemia: time-course and spatial analysis.
abstract: T-wave alternans (TWA) has been linked to increased vulnerability to ventricular fibrillation in different settings including myocardial ischemia. In this study, we propose a methodology for the characterization of TWA induced by transient, regional ischemia. We studied the prevalence, magnitude and spatio-temporal relationship between TWA and ischemia in 95 patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Two electrocardiogram records of each patient, a control recording before PTCA and the PTCA record, were analyzed using a robust, recently proposed method for TWA analysis. The detected episodes were characterized in terms of their time-course, lead distribution and alternans waveform. One third of the patients (33.7%) showed TWA episodes during PTCA. The highest prevalence (51.7%) and amplitude were found in patients with left anterior descendent artery occlusion. The onset of TWA was detected after the first 1-2 min of occlusion, suggesting that some level of ischemia must be attained before TWA arises, while disappearance of TWA following reperfusion was much more rapid. The TWA lead distributions and waveforms showed distinct distributions according to the occluded artery reflecting the regional nature of the TWA phenomenon.
authors.affiliation: Communications Technology Group, Aragon Institute of Engineering Research, University of Zaragoza, María de Luna 1, 50018 Zaragoza, Spain. jpmart@unizar.es
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Martínez
authors.forename: Salvador
authors.initials: S
authors.lastname: Olmos
authors.forename: Galen
authors.initials: G
authors.lastname: Wagner
authors.forename: Pablo
authors.initials: P
authors.lastname: Laguna
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015906:Angioplasty, Balloon, Coronary / Q000706:statistics & numerical data; D015897:Comorbidity; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013030:Spain / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*