title: Single-beat noninvasive imaging of ventricular endocardial and epicardial activation in patients undergoing CRT.
abstract: BACKGROUND
  Little is known about the effect of cardiac resynchronization therapy (CRT) on endo- and epicardial ventricular activation. Noninvasive imaging of cardiac electrophysiology (NICE) is a novel imaging tool for visualization of both epi- and endocardial ventricular electrical activation.
  
  
  RESULTS
  NICE was performed in ten patients with congestive heart failure (CHF) undergoing CRT and in ten patients without structural heart disease (control group). NICE is a fusion of data from high-resolution ECG mapping with a model of the patient's individual cardiothoracic anatomy created from magnetic resonance imaging. Beat-to-beat endocardial and epicardial ventricular activation sequences were computed during native rhythm as well as during ventricular pacing using a bidomain theory-based heart model to solve the related inverse problem. During right ventricular (RV) pacing control patients showed a deterioration of the ventricular activation sequence similar to the intrinsic activation pattern of CHF patients. Left ventricular propagation velocities were significantly decreased in CHF patients as compared to the control group (1.6±0.4 versus 2.1±0.5 m/sec; p<0.05). CHF patients showed right-to-left septal activation with the latest activation epicardially in the lateral wall of the left ventricle. Biventricular pacing resulted in a resynchronization of the ventricular activation sequence and in a marked decrease of total LV activation duration as compared to intrinsic conduction and RV pacing (129±16 versus 157±28 and 173±25 ms; both p<0.05).
  
  
  CONCLUSIONS
  Endocardial and epicardial ventricular activation can be visualized noninvasively by NICE. Identification of individual ventricular activation properties may help identify responders to CRT and to further improve response to CRT by facilitating a patient-specific lead placement and device programming.
authors.affiliation: Division of Cardiology, Department of Internal Medicine III, Medical University Innsbruck, Innsbruck, Austria. thomas.berger@uki.at
authors.forename: Thomas
authors.initials: T
authors.lastname: Berger
authors.forename: Bernhard
authors.initials: B
authors.lastname: Pfeifer
authors.forename: Friedrich F
authors.initials: FF
authors.lastname: Hanser
authors.forename: Florian
authors.initials: F
authors.lastname: Hintringer
authors.forename: Gerald
authors.initials: G
authors.lastname: Fischer
authors.forename: Michael
authors.initials: M
authors.lastname: Netzer
authors.forename: Thomas
authors.initials: T
authors.lastname: Trieb
authors.forename: Markus
authors.initials: M
authors.lastname: Stuehlinger
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Dichtl
authors.forename: Christian
authors.initials: C
authors.lastname: Baumgartner
authors.forename: Otmar
authors.initials: O
authors.lastname: Pachinger
authors.forename: Michael
authors.initials: M
authors.lastname: Seger
mesh_terms: D058406:Cardiac Resynchronization Therapy; D016022:Case-Control Studies; D003952:Diagnostic Imaging / Q000379:methods*; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D004699:Endocardium / Q000503:physiopathology*; D056149:Epicardial Mapping / Q000379:methods*; D006333:Heart Failure / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D010496:Pericardium / Q000503:physiopathology*