title: Efficiency, reproducibility and agreement of five different hemodynamic measures for optimization of cardiac resynchronization therapy.
abstract: BACKGROUND
  Several hemodynamic measures have been used for optimization of the AV delay of cardiac resynchronization therapy (CRT), including pulse pressure (PP), systolic blood pressure (SBP) and cardiac output (CO). We aimed to determine whether these measures identify the same optimum and whether they have the same efficiency and reproducibility at identifying this optimum.
  
  
  RESULTS
  In 22 patients with cardiac resynchronization therapy, we adjusted the AV delay while atrially pacing at 110 bpm and simultaneously recording SBP, diastolic blood pressure (DBP), PP, mean arterial pressure (MAP) and CO. SBP, PP and CO all had essentially the same signal-to-noise ratios (15.4+/-5.4, 15.5+/-6.4, 15.3+/-7.4 respectively p=NS). In contrast, MAP and DBP had significantly worse signal-to-noise ratios than SBP (14.2+/-5.6, p=0.003 and 12.1+/-4.4, p<0.0001 respectively). The optimal AV delay was very similar between SBP, PP, MAP and DBP. For example, the optima identified by SBP correlated strongly with those identified by PP (r=0.94), MAP (r=0.96) and DBP (r=0.90). In contrast, the optima detected by CO was poorly related to these (e.g. r=0.36 with SBP optima). Reproducibility was best for optima detected by SBP followed by MAP and PP.
  
  
  CONCLUSIONS
  Essentially the same AV optimum is identified, regardless of whether the parameter chosen for maximization is SBP, PP, MAP or DBP. We conclude that optimizing the CRT AV delay using SBP gives the best combination of efficiency and reproducibility, with PP and MAP being reasonable alternatives.
authors: International Centre for Circulatory Health, St Mary's Hospital and Imperial College, 59-61 North Wharf Road, W2 1LA, London, United Kingdom.
authors: Zachary I
authors: ZI
authors: Whinnett
authors: Justin E R
authors: JE
authors: Davies
authors: Gemma
authors: G
authors: Nott
authors: Keith
authors: K
authors: Willson
authors: Charlotte H
authors: CH
authors: Manisty
authors: Nicholas S
authors: NS
authors: Peters
authors: Prapa
authors: P
authors: Kanagaratnam
authors: D Wyn
authors: DW
authors: Davies
authors: Alun D
authors: AD
authors: Hughes
authors: Jamil
authors: J
authors: Mayet
authors: Darrel P
authors: DP
authors: Francis
mesh_terms: D000368:Aged; D054537:Atrioventricular Block / Q000503:physiopathology / Q000628:therapy*; D001283:Atrioventricular Node / Q000503:physiopathology*; D001794:Blood Pressure; D002037:Bundle-Branch Block; D002302:Cardiac Output; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D003971:Diastole; D005260:Female; D006305:Health Status Indicators; D006329:Heart Conduction System / Q000503:physiopathology*; D006334:Heart Function Tests; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013599:Systole