title: Detection of a and b waves in the acceleration photoplethysmogram.
abstract: BACKGROUND
  Analyzing acceleration photoplethysmogram (APG) signals measured after exercise is challenging. In this paper, a novel algorithm that can detect a waves and consequently b waves under these conditions is proposed. Accurate a and b wave detection is an important first step for the assessment of arterial stiffness and other cardiovascular parameters.
  
  
  METHODS
  Nine algorithms based on fixed thresholding are compared, and a new algorithm is introduced to improve the detection rate using a testing set of heat stressed APG signals containing a total of 1,540 heart beats.
  
  
  RESULTS
  The new a detection algorithm demonstrates the highest overall detection accuracy--99.78% sensitivity, 100% positive predictivity--over signals that suffer from 1) non-stationary effects, 2) irregular heartbeats, and 3) low amplitude waves. In addition, the proposed b detection algorithm achieved an overall sensitivity of 99.78% and a positive predictivity of 99.95%.
  
  
  CONCLUSIONS
  The proposed algorithm presents an advantage for real-time applications by avoiding human intervention in threshold determination.
authors.affiliation: Department of Computing Science, University of Alberta, 2-32 Athabasca Hall, T6G 2E1 Edmonton, Canada. moe.elgendi@gmail.com.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Elgendi
authors.forename: Ian
authors.initials: I
authors.lastname: Norton
authors.forename: Matt
authors.initials: M
authors.lastname: Brearley
authors.forename: Derek
authors.initials: D
authors.lastname: Abbott
authors.forename: Dale
authors.initials: D
authors.lastname: Schuurmans
mesh_terms: D000054:Acceleration; D000328:Adult; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000175:diagnosis; D064368:Healthy Volunteers; D006321:Heart / Q000033:anatomy & histology; D006339:Heart Rate; D006801:Humans; D008297:Male; D017156:Photoplethysmography / Q000379:methods*; D063177:Pulse Wave Analysis / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult