title: Imaging the Propagation of the Electromechanical Wave in Heart Failure Patients with Cardiac Resynchronization Therapy.
abstract: BACKGROUND
  Current electrocardiographic and echocardiographic measurements in heart failure (HF) do not take into account the complex interplay between electrical activation and local wall motion. The utilization of novel technologies to better characterize cardiac electromechanical behavior may lead to improved response rates with cardiac resynchronization therapy (CRT). Electromechanical wave imaging (EWI) is a noninvasive ultrasound-based technique that uses the transient deformations of the myocardium to track the intrinsic EW that precedes myocardial contraction. In this paper, we investigate the performance and reproducibility of EWI in the assessment of HF patients and CRT.
  
  
  METHODS
  EWI acquisitions were obtained in five healthy controls and 16 HF patients with and without CRT pacing. Responders (n = 8) and nonresponders (n = 8) to CRT were identified retrospectively on the basis of left ventricular (LV) reverse remodeling. Electromechanical activation maps were obtained in all patients and used to compute a quantitative parameter describing the mean LV lateral wall activation time (LWAT).
  
  
  RESULTS
  Mean LWAT was increased by 52.1 ms in HF patients in native rhythm compared to controls (P < 0.01). For all HF patients, CRT pacing initiated a different electromechanical activation sequence. Responders exhibited a 56.4-ms ± 28.9-ms reduction in LWAT with CRT pacing (P < 0.01), while nonresponders showed no significant change.
  
  
  CONCLUSIONS
  In this initial feasibility study, EWI was capable of characterizing local cardiac electromechanical behavior as it pertains to HF and CRT response. Activation sequences obtained with EWI allow for quantification of LV lateral wall electromechanical activation, thus providing a novel method for CRT assessment.
authors: Department of Biomedical Engineering, Columbia University, New York, New York.
authors: Ethan
authors: E
authors: Bunting
authors: Division of Cardiology, Columbia University, New York, New York.
authors: Litsa
authors: L
authors: Lambrakos
authors: Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands.
authors: Paul
authors: P
authors: Kemper
authors: Division of Cardiology, Columbia University, New York, New York.
authors: William
authors: W
authors: Whang
authors: Division of Cardiology, Columbia University, New York, New York.
authors: Hasan
authors: H
authors: Garan
authors: Department of Biomedical Engineering, Department of Radiology, Columbia University, New York, New York.
authors: Elisa
authors: E
authors: Konofagou
mesh_terms: D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods; D056966:Excitation Contraction Coupling; D005240:Feasibility Studies; D005260:Female; D006329:Heart Conduction System; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000517:prevention & control*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D009200:Myocardial Contraction; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
keywords: cardiac resynchronization therapy; electromechanical; heart failure; strain; ultrasound