title: Validation of a new index for estimating arterial stiffness: measurement of the QPV interval by Doppler ultrasound.
abstract: BACKGROUND
  Pulse wave velocity (PWV), a relevant indicator of arterial stiffness, can be measured noninvasively with a variety of automatic devices, but most are complexly equipped. We developed a novel index for estimating arterial stiffness as "QPV interval," which was determined by means of surface electrocardiogram and Doppler ultrasound of the brachial artery simultaneously.
  
  
  OBJECTIVE
  This study aimed to validate the QPV interval as an exact and convenient index for estimation of arterial stiffness.
  
  
  METHODS
  Forty-seven patients with untreated essential hypertension and 19 normotensive subjects were enrolled. Brachial-ankle PWV (baPWV) was measured using an automatic volume-plethysmographic apparatus, and Doppler ultrasound was implemented sequentially to measure the QPV interval in each subject. Clinical biochemistry and echocardiography were performed on the same day.
  
  
  RESULTS
  Mean baPWV was significantly higher in hypertensive patients than in normotensive subjects (p = 0.002), whereas mean QPV interval was significantly shorter in hypertensive patients than in the normotensive group (p = 0.019). A simple regression analysis demonstrated an inverse correlation between the QPV interval and baPWV (r = -0.671, p < 0.001) in all enrolled subjects. In a stepwise regression model that adjusted for age, systolic blood pressure, and other determinants of baPWV, the negative association remained between the QPV interval and baPWV (p < 0.001).
  
  
  CONCLUSIONS
  The QPV interval correlates inversely with baPWV, independent of age and other determinants of baPWV; hence, the QPV interval can serve as a simple and convenient index for assessing arterial stiffness in clinical practice.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kaohsiung Municipal United Hospital, Taiwan.
authors.forename: Min-Yi
authors.initials: MY
authors.lastname: Lee
authors.forename: Chih-Sheng
authors.initials: CS
authors.lastname: Chu
authors.forename: Kun-Tai
authors.initials: KT
authors.lastname: Lee
authors.forename: Chan-Ming
authors.initials: CM
authors.lastname: Wu
authors.forename: Ho-Min
authors.initials: HM
authors.lastname: Su
authors.forename: Shin-Jing
authors.initials: SJ
authors.lastname: Lin
authors.forename: Sheng-Hsiung
authors.initials: SH
authors.lastname: Sheu
authors.forename: Wen-Ter
authors.initials: WT
authors.lastname: Lai
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011673:Pulsatile Flow / Q000502:physiology; D012044:Regression Analysis; D018608:Ultrasonography, Doppler