title: Resynchronization of the left ventricular contraction by tailored programming of right and left ventricular pacing.
abstract: OBJECTIVE
  The prerequisite and the rationale for the benefit of cardiac resynchronization therapy (CRT) is that it is able to resynchronize left ventricular (LV) walls that have a delayed activation.
  
  
  RESULTS
  In 69 consecutive patients who underwent biventricular (BIV) pacemaker implantation, we assessed the magnitude of intraventricular resynchronization achieved by means of simultaneous (BIV 0) and sequential BIV pacing (with an individually optimized VV interval value among +80 ms and -80 ms) using pulsed-wave tissue Doppler imaging techniques and in particular the measurement of the intra-LV electromechanical delay. The intra-LV delay was defined as the difference between the longest and the shortest activation time in the six basal segments of the LV. An abnormal intra-LV delay was defined as a value >41 ms. The intra-LV delay was 63 +/- 28 ms baseline, decreased to 44 +/- 26 ms with BIV 0 and to 26 +/- 15 ms with optimized BIV (P = 0.001). BIV 0 determined the shortest delay in 28 (41%) patients (23 +/- 12 ms). In 41 (59%) patients, a better resynchronization was achieved with optimized VV intervals (LV first in 32 and RV first in 5) or single-chamber pacing (LV in 3 and RV in 1). With BIV 0, the intra-LV delay remained abnormal in 41% and was longer than baseline in 30% of patients compared with 9 and 12% with optimized BIV, respectively (P = 0.001).
  
  
  CONCLUSIONS
  A sub-optimal resynchronization is achieved with simultaneous BIV pacing in most patients. A tailored programming of the relative contribution of RV and LV pacing forms the prerequisite for improving CRT results.
authors.affiliation: Arrhythmologic Centre, Department of Cardiology, Ospedali del Tigullio, Via don Bobbio, 16033 Lavagna, Italy. mbrignole@asl4.liguria.it
authors.forename: Michele
authors.initials: M
authors.lastname: Brignole
authors.forename: Daniele
authors.initials: D
authors.lastname: Oddone
authors.forename: Roberto
authors.initials: R
authors.lastname: Maggi
authors.forename: Gabriele
authors.initials: G
authors.lastname: Lupi
authors.forename: Roberto
authors.initials: R
authors.lastname: Bollini
authors.forename: Serena
authors.initials: S
authors.lastname: Corallo
authors.forename: Stefano
authors.initials: S
authors.lastname: Robotti
authors.forename: Alberto
authors.initials: A
authors.lastname: Solano
authors.forename: Paolo
authors.initials: P
authors.lastname: Donateo
authors.forename: Francesco
authors.initials: F
authors.lastname: Croci
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010138:Pacemaker, Artificial; D011446:Prospective Studies; D012984:Software; D018617:Ultrasonography, Doppler, Pulsed; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy