title: Distribution of abnormal potentials in chronic myocardial infarction using a real time magnetic resonance guided electrophysiology system.
abstract: BACKGROUND
  Identification of viable slow conduction zones manifested by abnormal local potentials is integral to catheter ablation of ventricular tachycardia (VT) sites. The relationship between contrast patterns in cardiovascular magnetic resonance (CMR) and local electrical mapping is not well characterized. The purpose of this study was to identify regions of isolated, late and fractionated diastolic potentials in sinus rhythm and controlled-paced rhythm in post-infarct animals relative to regions detected by late gadolinium enhancement CMR (LGE-CMR).
  
  
  METHODS
  Using a real-time MR-guided electrophysiology system, electrogram (EGM) recordings were used to generate endocardial electroanatomical maps in 6 animals. LGE-CMR was also performed and tissue classification (dense infarct, gray zone and healthy myocardium) was then correlated to locations of abnormal potentials.
  
  
  RESULTS
  For abnormal potentials in sinus rhythm, relative occurrence was equivalent 24%, 27% and 22% in dense scar, gray zone and healthy tissue respectively (p = NS); in paced rhythm, the relative occurrence of abnormal potentials was found to be different with 30%, 42% and 21% in dense scar, gray zone and healthy myocardium respectively (p = 0.001). For location of potentials, in the paced case, the relative frequency of abnormal EGMs was 19.9%, 65.4% and 14.7% in the entry, central pathway and exit respectively (p = 0.05), putative regions being defined by activation times.
  
  
  CONCLUSIONS
  Our data suggests that gray zone quantified by LGE-CMR exhibits abnormal potentials more frequently than in healthy tissue or dense infarct when right ventricular apex pacing is used.
authors.affiliation: Medical Biophysics, University Of Toronto, Toronto, ON, Canada. soduneye@sri.utoronto.ca.
authors.forename: Samuel O
authors.initials: SO
authors.lastname: Oduneye
authors.affiliation: Medical Biophysics, University Of Toronto, Toronto, ON, Canada. mpop@sri.utoronto.ca.|Imaging Research, Sunnybrook Research Institute, Toronto, ON, Canada. mpop@sri.utoronto.ca.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Pop
authors.affiliation: Arrhythmia Services, Sunnybrook Health Science Centre, Toronto, ON, Canada. mohammed.shurrab@sunnybrook.ca.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Shurrab
authors.affiliation: Imaging Research, Sunnybrook Research Institute, Toronto, ON, Canada. lbiswas@swri.ca.
authors.forename: Labonny
authors.initials: L
authors.lastname: Biswas
authors.affiliation: Imaging Research, Sunnybrook Research Institute, Toronto, ON, Canada. venkat@sri.utoronto.ca.
authors.forename: Venkat
authors.initials: V
authors.lastname: Ramanan
authors.affiliation: Imaging Research, Sunnybrook Research Institute, Toronto, ON, Canada. jbarry@sri.utoronto.ca.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Barry
authors.affiliation: Arrhythmia Services, Sunnybrook Health Science Centre, Toronto, ON, Canada. Eugene.Crystal@sunnybrook.ca.
authors.forename: Eugene
authors.initials: E
authors.lastname: Crystal
authors.affiliation: Medical Biophysics, University Of Toronto, Toronto, ON, Canada. gawright@sri.utoronto.ca.|Imaging Research, Sunnybrook Research Institute, Toronto, ON, Canada. gawright@sri.utoronto.ca.
authors.forename: Graham A
authors.initials: GA
authors.lastname: Wright
mesh_terms: D000200:Action Potentials; D000818:Animals; D002304:Cardiac Pacing, Artificial; D003287:Contrast Media / Q000008:administration & dosage; D004195:Disease Models, Animal; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006329:Heart Conduction System / Q000503:physiopathology*; D019028:Magnetic Resonance Imaging, Cine; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D013552:Swine; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA