Interplay of electrical wavefronts as determinant of the response to cardiac resynchronization therapy in dyssynchronous canine hearts

Marc Strik, Lars B van Middendorp, Patrick Houthuizen, Sylvain Ploux, Arne van Hunnik, Marion Kuiper, Angelo Auricchio, Frits W Prinzen

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

BACKGROUND: The relative contribution of electromechanical synchronization and ventricular filling to the optimal hemodynamic effect in cardiac resynchronization therapy (CRT) during adjustment of stimulation-timings is incompletely understood. We investigated whether optimal hemodynamic effect in CRT requires collision of pacing-induced and intrinsic activation waves and optimal filling of the left ventricle (LV).

METHODS AND RESULTS: CRT was performed in dogs with chronic left bundle-branch block (n=8) or atrioventricular (AV) block (n=6) through atrial (A), right ventricular (RV) apex, and LV-basolateral pacing. A 100 randomized combinations of A-LV/A-RV intervals were tested. Total activation time (TAT) was calculated from >100 contact mapping electrodes. Mechanical interventricular dyssynchrony was determined as the time delay between upslopes of LV and RV pressure curves. Settings providing an increase in LVdP/dtmax (maximal rate of rise of left ventricular pressure) of ≥90% of the maximum LVdP/dtmax value were defined as optimal (CRTopt). Filling was assessed by changes in LV end-diastolic volume (EDV; conductance catheter technique). In all hearts, CRTopt was observed during multiple settings, providing an average LVdP/dtmax increase of ≈15%. In AV-block hearts, CRTopt exclusively depended on interventricular-interval and not on AV-interval. In left bundle-branch block hearts, CRTopt occurred at A-LV intervals that allowed fusion of LV-pacing-derived activation with right bundle-derived activation. In all animals, CRTopt occurred at settings resulting in the largest decrease in TAT and mechanical interventricular dyssynchrony, whereas LV EDV hardly changed.

CONCLUSIONS: In left bundle-branch block and AV-block hearts, optimal hemodynamic effect of CRT depends on optimal interplay between pacing-induced and intrinsic activation waves and the corresponding mechanical resynchronization rather than filling.

Original languageEnglish
Pages (from-to)924-31
Number of pages8
JournalCirculation. Arrhythmia and electrophysiology
Volume6
Issue number5
DOIs
Publication statusPublished - Oct 2013

Keywords

  • Animals
  • Atrioventricular Block
  • Bundle-Branch Block
  • Cardiac Resynchronization Therapy
  • Disease Models, Animal
  • Dogs
  • Electrocardiography
  • Equipment Design
  • Hemodynamics
  • Random Allocation
  • Journal Article
  • Research Support, Non-U.S. Gov't

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