title: Insights from Novel Noninvasive CT and ECG Imaging Modalities on Electromechanical Myocardial Activation in a Canine Model of Ischemic Dyssynchronous Heart Failure.
abstract: The interplay between electrical activation and mechanical contraction patterns is hypothesized to be central to reduced effectiveness of cardiac resynchronization therapy (CRT). Furthermore, complex scar substrates render CRT less effective. We used novel cardiac computed tomography (CT) and noninvasive electrocardiographic imaging (ECGI) techniques in an ischemic dyssynchronous heart failure (DHF) animal model to evaluate electrical and mechanical coupling of cardiac function, tissue viability, and venous accessibility of target pacing regions.
  
  
  
  Ischemic DHF was induced in 6 dogs using coronary occlusion, left bundle ablation and tachy RV pacing. Full body ECG was recorded during native rhythm followed by volumetric first-pass and delayed enhancement CT. Regional electrical activation were computed and overlaid with segmented venous anatomy and scar regions. Reconstructed electrical activation maps show consistency with LBBB starting on the RV and spreading in a "U-shaped" pattern to the LV. Previously reported lines of slow conduction are seen parallel to anterior or inferior interventricular grooves. Mechanical contraction showed large septal to lateral wall delay (80 ± 38 milliseconds vs. 123 ± 31 milliseconds, P = 0.0001). All animals showed electromechanical correlation except dog 5 with largest scar burden. Electromechanical decoupling was largest in basal lateral LV segments.
  
  
  
  We demonstrated a promising application of CT in combination with ECGI to gain insight into electromechanical function in ischemic dyssynchronous heart failure that can provide useful information to study regional substrate of CRT candidates.
authors: Division of Cardiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors: Fady
authors: F
authors: Dawoud
authors: Division of Cardiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors: Karl H
authors: KH
authors: Schuleri
authors: Division of Cardiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors: David D
authors: DD
authors: Spragg
authors: Department of Electrical and Computer Engineering, Dalhousie University, Halifax, NS, Canada.
authors: B Milan
authors: BM
authors: Horáček
authors: Division of Cardiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors: Ronald D
authors: RD
authors: Berger
authors: Division of Cardiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors: Henry R
authors: HR
authors: Halperin
authors: Division of Cardiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.|Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
authors: Albert C
authors: AC
authors: Lardo
mesh_terms: D000200:Action Potentials; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D001696:Biomechanical Phenomena; D018780:Body Surface Potential Mapping; D004195:Disease Models, Animal; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology*; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D006339:Heart Rate; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology; D011237:Predictive Value of Tests; D014022:Tissue Survival; D014057:Tomography, X-Ray Computed
keywords: CT; cardiac resynchronization therapy; dyssynchrony; electrocardiographic imaging; electromechanical coupling