title: Cardiac resynchronization therapy optimization by finger plethysmography.
abstract: OBJECTIVE
  We tested a simple noninvasive method for cardiac resynchronization therapy (CRT) optimization using standard finger photoplethysmography (FPPG).
  
  
  BACKGROUND
  CRT can increase left ventricular cardiac output in patients with heart failure and ventricular conduction delay. Optimal therapy delivery depends on an appropriate AV delay. Multiple invasive and noninvasive methods have been attempted to identify patients and the best AV delay for CRT, but all suffer from a combination of high patient risk, cost, complexity, and low reproducibility.
  
  
  METHODS
  FPPG and invasive aortic pressure data were simultaneously collected from 57 heart failure patients during intrinsic rhythm alternating with very brief periods of pacing at 4 to 5 AV delays. After correcting data for artifacts, the median percentage responses for each AV delay were classified as positive, negative, or neutral compared to baseline (Wilcoxon rank test).
  
  
  RESULTS
  FPPG correctly identified positive aortic pulse pressure responses with 71% sensitivity (95% CI: 60-80%) and 90% specificity (95% CI: 84-94%) and negative aortic pulse pressure responses with 57% sensitivity (95% CI: 44-69%) and 96% specificity (95% CI: 91-98%). The magnitude of FPPG changes were strongly correlated with positive aortic pulse pressure changes (R(2) = 0.73, P < .0001) but less well correlated with negative aortic pulse pressure changes (R(2) = 0.43, P < .0001). FPPG selected 78% of the patients having positive aortic pulse pressure changes to CRT and identified the AV delay giving maximum aortic pulse pressure change in all selected patients.
  
  
  CONCLUSIONS
  FPPG can provide a simple noninvasive method for identifying significant changes in aortic pulse pressure with high specificity, including identifying patients in whom aortic pulse pressure increases with CRT and the AV delay giving the maximum aortic pulse pressure.
authors.affiliation: Department of Cardiology, German Heart Institute Berlin. c.butter@immanuel.de
authors.forename: Christian
authors.initials: C
authors.lastname: Butter
authors.forename: Christoph
authors.initials: C
authors.lastname: Stellbrink
authors.forename: Andres
authors.initials: A
authors.lastname: Belalcazar
authors.forename: Don
authors.initials: D
authors.lastname: Villalta
authors.forename: Michael
authors.initials: M
authors.lastname: Schlegl
authors.forename: Anil
authors.initials: A
authors.lastname: Sinha
authors.forename: Francisca
authors.initials: F
authors.lastname: Cuesta
authors.forename: Craig
authors.initials: C
authors.lastname: Reister
mesh_terms: D001011:Aorta / Q000503:physiopathology*; D001283:Atrioventricular Node / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods; D002304:Cardiac Pacing, Artificial; D005260:Female; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D017156:Photoplethysmography / Q000379:methods*; D012680:Sensitivity and Specificity