title: Noninvasive cardiac activation imaging of ventricular arrhythmias during drug-induced QT prolongation in the rabbit heart.
abstract: BACKGROUND
  Imaging myocardial activation from noninvasive body surface potentials promises to aid in both cardiovascular research and clinical medicine.
  
  
  OBJECTIVE
  To investigate the ability of a noninvasive 3-dimensional cardiac electrical imaging technique for characterizing the activation patterns of dynamically changing ventricular arrhythmias during drug-induced QT prolongation in rabbits.
  
  
  METHODS
  Simultaneous body surface potential mapping and 3-dimensional intracardiac mapping were performed in a closed-chest condition in 8 rabbits. Data analysis was performed on premature ventricular complexes, couplets, and torsades de pointes (TdP) induced during intravenous administration of clofilium and phenylephrine with combinations of various infusion rates.
  
  
  RESULTS
  The drug infusion led to a significant increase in the QT interval (from 175 ± 7 to 274 ± 31 ms) and rate-corrected QT interval (from 183 ± 5 to 262 ± 21 ms) during the first dose cycle. All the ectopic beats initiated by a focal activation pattern. The initial beat of TdPs arose at the focal site, whereas the subsequent beats were due to focal activity from different sites or 2 competing focal sites. The imaged results captured the dynamic shift of activation patterns and were in good correlation with the simultaneous measurements, with a correlation coefficient of 0.65 ± 0.02 averaged over 111 ectopic beats. Sites of initial activation were localized to be ~5 mm from the directly measured initiation sites.
  
  
  CONCLUSIONS
  The 3-dimensional cardiac electrical imaging technique could localize the origin of activation and image activation sequence of TdP during QT prolongation induced by clofilium and phenylephrine in rabbits. It offers the potential to noninvasively investigate the proarrhythmic effects of drug infusion and assess the mechanisms of arrhythmias on a beat-to-beat basis.
authors.affiliation: Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Chengzong
authors.initials: C
authors.lastname: Han
authors.forename: Steven M
authors.initials: SM
authors.lastname: Pogwizd
authors.forename: Cheryl R
authors.initials: CR
authors.lastname: Killingsworth
authors.forename: Zhaoye
authors.initials: Z
authors.lastname: Zhou
authors.forename: Bin
authors.initials: B
authors.lastname: He
mesh_terms: D000818:Animals; D000889:Anti-Arrhythmia Agents; D018780:Body Surface Potential Mapping / Q000379:methods*; D002316:Cardiotonic Agents; D004195:Disease Models, Animal; D004562:Electrocardiography; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D021621:Imaging, Three-Dimensional; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000150:complications / Q000503:physiopathology; D008297:Male; D010656:Phenylephrine; D000644:Quaternary Ammonium Compounds; D011817:Rabbits; D016171:Torsades de Pointes / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D018879:Ventricular Premature Complexes / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*
chemical_list: D000889:Anti-Arrhythmia Agents; D002316:Cardiotonic Agents; D000644:Quaternary Ammonium Compounds; D010656:Phenylephrine; C022799:clofilium
keywords: 3-dimensional; 3-dimensional cardiac electrical imaging; 3D; 3DCEI; BSPM; CC; CL; Cardiac imaging; Cardiac mapping; EAD; ECG; Electrocardiography; LE; LV; PVC; QT prolongation; QTc; RV; RVOT; Rabbit model; TAT; TdP; Torsades de pointes; UFCT; body surface potential map; correlation coefficient; cycle length; early afterdepolarization; electrocardiographic/electrocardiogram; left ventricle/ventricular; localization error; premature ventricular complex; rate-corrected QT; right ventricle/ventricular; right ventricular outflow tract; torsades de pointes; total activation time; ultrafast computed tomography