title: T-wave morphology after epinephrine bolus may reveal silent long QT syndrome mutation carriers.
abstract: BACKGROUND
  Long QT syndrome (LQTS) gene mutation carriers with indeterminate electrocardiogram frequently escape clinical diagnosis. We assessed the use of epinephrine bolus injection in revealing T-wave abnormalities.
  
  
  METHODS
  We recruited 30 genotyped asymptomatic LQTS gene carriers with nondiagnostic QT interval and 15 controls. Electrocardiogram was recorded with body surface potential mapping after an intravenous epinephrine bolus. T-wave morphology was determined as normal, biphasic, inverted, bifid, or combined pattern.
  
  
  RESULTS
  Long QT syndrome carriers and healthy controls had different T-wave profiles (P = .027). Of controls, 12 (80%) of 15 had no change or biphasic appearance, whereas only 10 (33%) of 30 of LQTS carriers had so. Bifid or combined pattern occurred in 15 (50%) of 30 in LQTS and in 6 (60%) of 10 in the LQT3 subgroup but only in 1 (7%) of 15 of healthy.
  
  
  CONCLUSIONS
  Modification of ventricular repolarization with low-dose epinephrine injection helps to distinguish silent LQTS mutation carriers. This concerns also the LQT3 subtype, which may escape tests.
authors.affiliation: Helsinki University Central Hospital, Department of Cardiology, Helsinki, Finland. Electronic address: anna-mari.hekkala@hel.fi.
authors.forename: Anna-Mari
authors.initials: AM
authors.lastname: Hekkala
authors.affiliation: Aalto University, Department of Biomedical Engineering and Computational Science, Espoo, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Väänänen
authors.affiliation: Helsinki University Central Hospital, Department of Cardiology, Helsinki, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Swan
authors.affiliation: Helsinki University Central Hospital, Department of Cardiology, Helsinki, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Viitasalo
authors.affiliation: Helsinki University Central Hospital, Department of Cardiology, Helsinki, Finland.
authors.forename: Lauri
authors.initials: L
authors.lastname: Toivonen
mesh_terms: D000328:Adult; D058070:Asymptomatic Diseases; D018780:Body Surface Potential Mapping; D000072237:ERG1 Potassium Channel; D004837:Epinephrine / Q000008:administration & dosage; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics*; D005260:Female; D006580:Genetic Carrier Screening; D005838:Genotype; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D051657:KCNQ1 Potassium Channel / Q000235:genetics*; D008133:Long QT Syndrome / Q000145:classification / Q000175:diagnosis* / Q000235:genetics*; D008297:Male; D009154:Mutation; D062554:NAV1.5 Voltage-Gated Sodium Channel; D015222:Sodium Channels / Q000235:genetics*
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D051657:KCNQ1 Potassium Channel; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D015222:Sodium Channels; D004837:Epinephrine