title: An ultrasound look at Korotkoff sounds: the role of pulse wave velocity and flow turbulence.
abstract: OBJECTIVE
  The aim of this study was to analyze the temporal relationships between pressure, flow, and Korotkoff sounds, providing clues for their comprehensive interpretation.
  
  
  METHODS
  When measuring blood pressure in a group of 23 volunteers, we used duplex Doppler ultrasonography to assess, under the arm-cuff, the brachial artery flow, diameter changes, and local pulse wave velocity (PWV), while recording Korotkoff sounds 10 cm downstream together with cuff pressure and ECG.
  
  
  RESULTS
  The systolic (SBP) and diastolic (DBP) blood pressures were 118.8±17.7 and 65.4±10.4 mmHg, respectively (n=23). The brachial artery lumen started opening when cuff pressure decreased below the SBP and opened for an increasing length of time until cuff pressure reached the DBP, and then remained open but pulsatile. A high-energy low-frequency Doppler signal, starting a few milliseconds before flow, appeared and disappeared together with Korotkoff sounds at the SBP and DBP, respectively. Its median duration was 42.7 versus 41.1 ms for Korotkoff sounds (P=0.54; n=17). There was a 2.20±1.54 ms/mmHg decrement in the time delay between the ECG R-wave and the Korotkoff sounds during cuff deflation (n=18). The PWV was 10±4.48 m/s at null cuff pressure and showed a 0.62% decrement per mmHg when cuff pressure increased (n=13).
  
  
  CONCLUSIONS
  Korotkoff sounds are associated with a high-energy low-frequency Doppler signal of identical duration, typically resulting from wall vibrations, followed by flow turbulence. Local arterial PWV decreases when cuff pressure increases. Exploiting these changes may help improve SBP assessment, which remains a challenge for oscillometric techniques.
authors.affiliation: aVascular Medicine and Laboratory, Nimes University Hospital, and EA2992 Research Unit, Montpellier University, Nimes bLaboratoire d'Informatique, de Robotique et de Microélectronique de Montpellier, CNRS-Montpellier University UMR 5506, Montpellier, France cBiomedical Engineering Laboratory, Faculty of Technology, Aboubekr Belkaid University, Tlemcen, Algeria.
authors.forename: Amir
authors.initials: A
authors.lastname: Benmira
authors.forename: Antonia
authors.initials: A
authors.lastname: Perez-Martin
authors.forename: Iris
authors.initials: I
authors.lastname: Schuster
authors.forename: Florent
authors.initials: F
authors.lastname: Veye
authors.forename: Jean
authors.initials: J
authors.lastname: Triboulet
authors.forename: Nicolas
authors.initials: N
authors.lastname: Berron
authors.forename: Isabelle
authors.initials: I
authors.lastname: Aichoun
authors.forename: Sarah
authors.initials: S
authors.lastname: Coudray
authors.forename: Jérémy
authors.initials: J
authors.lastname: Laurent
authors.forename: Fethi
authors.initials: F
authors.lastname: Bereksi-Reguig
authors.forename: Michel
authors.initials: M
authors.lastname: Dauzat
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology*; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D063177:Pulse Wave Analysis; D018616:Ultrasonography, Doppler, Duplex