title: Improved response to cardiac resynchronization therapy through optimization of atrioventricular and interventricular delays using acoustic cardiography: a pilot study.
abstract: BACKGROUND
  The purpose of this pilot study was to determine the utility of acoustic cardiography for the optimization of atrioventricular (AV) and interventricular (VV) delays in cardiac resynchronization therapy (CRT).
  
  
  RESULTS
  We evaluated 14 patients (86% male, mean age 64 +/- 9 years, mean time since implant 15 +/- 18 months). Subjects were enrolled >10 weeks after CRT implant. Spiroergometry and 2-dimensional/3-dimensional echocardiography were used to assess cardiac performance for "out-of-the-box" settings (baseline settings: AV 120 ms, VV 0 ms) versus optimal settings (determined by acoustic cardiography). Cardiac performance measurements were performed 6 weeks after settings were modified. Optimal AV/VV settings were determined based on the lowest electromechanical activation time (EMAT, the time from the onset of QRS to the mitral valve component of the first heart sound). Statistical analysis was performed using a paired 2-tailed Student's t-test. In comparison to "out-of-the-box" settings, AV/VV delay optimization with acoustic cardiography improved cardiac performance as indicated by significant changes in work capacity, maximum oxygen uptake, oxygen pulse, ejection fraction, end-systolic volume, and velocity-time integral in left ventricular outflow tract.
  
  
  CONCLUSIONS
  AV and VV optimization by acoustic cardiography produces significant improvements in objective clinical and hemodynamic parameters in comparison to typical "out-of-the-box" settings.
authors.affiliation: Division of Cardiology, Kantonsspital Luzern, Lucerne, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Toggweiler
authors.forename: Michel
authors.initials: M
authors.lastname: Zuber
authors.forename: Richard
authors.initials: R
authors.lastname: Kobza
authors.forename: Markus
authors.initials: M
authors.lastname: Roos
authors.forename: Peiman
authors.initials: P
authors.lastname: Jamshidi
authors.forename: Rolf
authors.initials: R
authors.lastname: Meier
authors.forename: Paul
authors.initials: P
authors.lastname: Erne
mesh_terms: D000162:Acoustics; D000368:Aged; D016275:Atrial Function / Q000502:physiology*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013997:Time Factors; D016276:Ventricular Function / Q000502:physiology*