title: QT interval heterogeneities induced through local epicardial warming/cooling. An experimental study.
abstract: OBJECTIVE
  Abnormal QT interval durations and dispersions have been associated with increased risk of ventricular arrhythmias. The present study examines the possible arrhythmogenic effect of inducing QT interval variations through local epicardial cooling and warming.
  
  
  METHODS
  In 10 isolated rabbit hearts, the temperatures of epicardial regions of the left ventricle were modified in a stepwise manner (from 22°C to 42°C) with simultaneous electrogram recording in these regions and in others of the same ventricle. QT and activation-recovery intervals were determined during sinus rhythm, whereas conduction velocity and ventricular arrhythmia induction were determined during programmed stimulation.
  
  
  RESULTS
  In the area modified from baseline temperature (37°C), the QT (standard deviation) was prolonged with maximum hypothermia (195 [47] vs 149 [12] ms; P<.05) and shortened with hyperthermia (143 [18] vs 152 [27] ms; P<.05). The same behavior was displayed for the activation-recovery interval. The conduction velocity decreased with hypothermia and increased with hyperthermia. No changes were seen in the other unmodified area. Repetitive responses were seen in 5 experiments, but no relationship was found between their occurrence and hypothermia or hyperthermia (P>.34).
  
  
  CONCLUSIONS
  In the experimental model employed, local variations in the epicardial temperature modulate the QT interval, activation-recovery interval, and conduction velocity. Induction of heterogeneities did not promote ventricular arrhythmia occurrence.
authors.affiliation: ITACA, Universitat Politècnica de València, Valencia, Spain. Electronic address: aguill@eln.upv.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Guill
authors.affiliation: ITACA, Universitat Politècnica de València, Valencia, Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Tormos
authors.affiliation: ITACA, Universitat Politècnica de València, Valencia, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Millet
authors.affiliation: ITACA, Universitat Politècnica de València, Valencia, Spain.
authors.forename: Eduardo J
authors.initials: EJ
authors.lastname: Roses
authors.affiliation: ITACA, Universitat Politècnica de València, Valencia, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Cebrián
authors.affiliation: Departamento de Fisioterapia, Universitat de València, Valencia, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Such-Miquel
authors.affiliation: Departamento de Fisiología, Universitat de València, Valencia, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Such
authors.affiliation: Departamento de Fisiología, Universitat de València, Valencia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Zarzoso
authors.affiliation: Departamento de Fisiología, Universitat de València, Valencia, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Alberola
authors.affiliation: Servicio de Cardiología, Hospital Clínic Universitari, Valencia, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Chorro
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000503:physiopathology; D003080:Cold Temperature / Q000009:adverse effects; D004558:Electric Stimulation; D004562:Electrocardiography; D006329:Heart Conduction System / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects; D010496:Pericardium / Q000502:physiology*; D011817:Rabbits; D016276:Ventricular Function / Q000502:physiology
keywords: Arrhythmia; Arritmia; Electrical stimulation; Electrofisiología; Electrophysiology; Estimulación eléctrica; Left ventricle; Ventrículo izquierdo