title: Beat-to-beat repolarization variability measured by T wave spectral variance index in chronic infarcted animals.
abstract: BACKGROUND
  Recent experimental and clinical studies have shown that beat-to-beat variability of repolarization morphology is associated with an increased risk for developing malignant ventricular arrhythmias. However, few data exist on the relationship between beat-to-beat repolarization variability and myocardial infarction itself.
  
  
  RESULTS
  In the present work we tested the algorithm of T wave spectral variance (TWSV) using the two dimension fast Fourier transform, in an animal model of myocardial infarction to extend the evidences that support the existence of beat-to-beat alteration in repolarization during the chronic stage of myocardial infarction. Thirty-four New Zealand rabbits were included in the study and divided in two groups. Group I (N = 24) exposed to surgical ligation of the left anterior descendent coronary artery. Group II (N = 10) sham operated animals. The TWSV index was calculated before and after 15 and 45 days of surgery. Both groups showed significant increments in TWSV after 15 days postsurgery. However, while the sham animals return to its control value, the infarcted group exhibited values of the TWSV index that remains significantly high after 45 days of surgery, with a mean increment of 28.7% (P < 0.05 against sham). Moreover, when the infarcted group was qualitatively divided in three subgroups, according to its infarction areas, a trend was found in the correlation between the magnitude of the infarcted area and the TWSV index.
  
  
  CONCLUSIONS
  This noninvasive measure confirms the presence of temporal repolarization variability associated with chronic myocardial infarction and further contributes to identify the infarcted animals.
authors.affiliation: Cardiac Electrophysiology Laboratory, Physiology Department, Favaloro University, Solis 453, Buenos Aires (1078), Argentina.
authors.forename: Esteban Raúl
authors.initials: ER
authors.lastname: Valverde
authors.forename: Ricardo Alberto
authors.initials: RA
authors.lastname: Quinteiro
authors.forename: Pedro David
authors.initials: PD
authors.lastname: Arini
authors.forename: Guillermo Claudio
authors.initials: GC
authors.lastname: Bertrán
authors.forename: Marcelo Oscar
authors.initials: MO
authors.lastname: Biagetti
mesh_terms: D000465:Algorithms; D000818:Animals; D002908:Chronic Disease; D003331:Coronary Vessels / Q000601:surgery; D004562:Electrocardiography; D005583:Fourier Analysis; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D009203:Myocardial Infarction / Q000503:physiopathology*; D011817:Rabbits