title: Implantable defibrillator electrograms and origin of left ventricular impulses: an analysis of regionalization ability and visual spatial resolution.
abstract: BACKGROUND
  The implantable cardioverter-defibrillator (ICD) electrogram (EG) is a documentation of ventricular tachycardia. We prospectively analyzed EGs from ICD electrodes located at the right ventricle apex to establish (1) ability to regionalize origin of left ventricle (LV) impulses, and (2) spatial resolution to distinguish between paced sites.
  
  
  RESULTS
  LV electro-anatomic maps were generated in 15 patients. ICD-EGs were recorded during pacing from 22 ± 10 LV sites. Voltage of far-field EG deflections (initial, peak, final) and time intervals between far-field and bipolar EGs were measured. Blinded visual analysis was used for spatial resolution. Initial deflections were more negative and initial/peak ratios were larger for lateral versus septal and superior versus inferior sites. Time intervals were shorter for apical versus basal and septal versus lateral sites. Best predictive cutoff values were voltage of initial deflection <-1.24 mV, and initial/peak ratio >0.45 for a lateral site, voltage of final deflection <-0.30 for an inferior site, and time interval <80 milliseconds for an apical site. In a subsequent group of 9 patients, these values predicted correctly paced site location in 54-75% and tachycardia exit site in 60-100%. Recognition of paced sites as different by EG inspection was 91% accurate. Sensitivity increased with distance (0.96 if ≥ 2 cm vs 0.84 if < 2 cm, P < 0.001) and with presence of low-voltage tissue between sites (0.94 vs 0.88, P < 0.001).
  
  
  CONCLUSIONS
  Standard ICD-EG analysis can help regionalize LV sites of impulse formation. It can accurately distinguish between 2 sites of impulse formation if they are ≥2 cm apart.
authors.affiliation: Cardiology Department, Hospital General Universitario Gregorio Marañon, Spain. almendral@secardiologia.es
authors.forename: Jesús
authors.initials: J
authors.lastname: Almendral
authors.forename: Felipe
authors.initials: F
authors.lastname: Atienza
authors.forename: Estrella
authors.initials: E
authors.lastname: Everss
authors.forename: Loreto
authors.initials: L
authors.lastname: Castilla
authors.forename: Esteban
authors.initials: E
authors.lastname: Gonzalez-Torrecilla
authors.forename: José
authors.initials: J
authors.lastname: Ormaetxe
authors.forename: Angel
authors.initials: A
authors.lastname: Arenal
authors.forename: Mercedes
authors.initials: M
authors.lastname: Ortiz
authors.forename: Margarita
authors.initials: M
authors.lastname: Sanromán-Junquera
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Mora-Jiménez
authors.forename: José M
authors.initials: JM
authors.lastname: Bellon
authors.forename: José L
authors.initials: JL
authors.lastname: Rojo
mesh_terms: D002304:Cardiac Pacing, Artificial; D017147:Defibrillators, Implantable; D016002:Discriminant Analysis; D004554:Electric Countershock / Q000295:instrumentation*; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted; D013030:Spain; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D016277:Ventricular Function, Left