Use of relaxation time as a marker for arterial distensibility
Download
1 / 19

Use of Relaxation Time as a Marker for Arterial Distensibility - PowerPoint PPT Presentation


  • 93 Views
  • Uploaded on

Use of Relaxation Time as a Marker for Arterial Distensibility. C.C. Winchester, N.-Y. Chou, and L.W. Winchester University of Mary Washington, Fredericksburg, VA, USA CW Optics, Inc., Seaford, VA, USA. EMBS 2008. Arterial Distensibility and Cardiovascular Disease.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Use of Relaxation Time as a Marker for Arterial Distensibility' - chika


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Use of relaxation time as a marker for arterial distensibility

Use of Relaxation Time as a Marker for Arterial Distensibility

C.C. Winchester, N.-Y. Chou, and L.W. Winchester

University of Mary Washington, Fredericksburg, VA, USA

CW Optics, Inc., Seaford, VA, USA

EMBS 2008


Arterial distensibility and cardiovascular disease
Arterial Distensibility and Cardiovascular Disease

  • Distensibility: arterial distension/pulse pressure

  • Associated with a number of cardiovascular risk factors

  • Early detection

EMBS 2008 2



Current methods of assessing arterial distensibility
Current Methods of Assessing Arterial Distensibility

  • Ankle Brachial Index (ABI)

  • Intima-Media Thickness (IMT)

  • Flow-Mediated Dilation (FMD)

EMBS 2008 4


Arterial relaxation time
Arterial Relaxation Time

  • The time it takes to relax to the baseline diameter

  • Uses timing measurements of the pulse waves to infer the conditions of peripheral arteries

EMBS 2008 5


Protocol
Protocol

  • Two different sensors, piezoelectric and photoelectric, on each hand

  • Collect baseline data with hands at heart-level

  • Arm raised while data were collected for another 400 s

EMBS 2008 6


Data collection
Data Collection

  • Sensors connected to storage oscilloscope

  • Oscilloscope connected to computer

  • >1kHz acquisition rate

EMBS 2008 7


Data analysis
Data Analysis

  • Savitzky-Golay fourth-order filtering technique

  • Peak detection algorithm

  • Computed time delays

EMBS 2008 8


Both Hands at Heart Level

Right Arm Raised

EMBS 2008 9



Observations
Observations

  • Decreased blood velocity in the right arm and a delay in pulse waveform in that arm as compared to the left arm (control)

  • After sudden dilation, brachial artery relaxes back to its normal condition as indicated by the delay approaching that of the baseline.

EMBS 2008 11


Subject characteristics
Subject Characteristics

  • Normotensive

    • 6 female, 4 male

    • Ages 19-60

  • Hypertensive

    • 4 male

    • 3 overweight, 1 with pacemaker

EMBS 2008 12


Computations
Computations

  • Delay times were fitted to the equation below

Y delay time

A constant

B maximum time delay before raising the arm

T0 time where subject raised arm

Τx relaxation time

EMBS 2008 13


Results
Results

  • Normal τP: 78.8 ± 15.60 s

  • Hypertensive τP: 584 ± 116 s

  • Normal τV: 50.45 ± 16.28 s

  • Hypertensive τV: unable to determine

EMBS 2008 14


Constant flow
Constant Flow

  • r: radius; 4.46 mm (Betik et al.)

  • v: velocity

  • 1: control; before raising the arm

  • 2: after raising the arm

EMBS 2008 15


Time delay
Time Delay

Using the measured time delay and an estimated length of the brachial artery(35 cm), the relationship between V1 and V2 can be determined.

EMBS 2008 16


Comparison with fmd
Comparison with FMD

  • a dilation of 3% is computed

  • In agreement with values of 3% to 8% obtained from ultrasound measurements (Pyke et al., Betik et al., Stoner et al.)

EMBS 2008 17


Clinical applications future work
Clinical Applications/Future Work

  • The extent of which venous emptying stimulates arterial dilation

  • Routinely conducted and reviewed in-office measurements

  • Regularly conducted to monitor pre-atherosclerotic patients and other at risk patients

  • Larger study to investigate relaxation time pre-hypertensive subjects

EMBS 2008 18


Acknowledgments
Acknowledgments

  • CW Optics, Inc

  • Volunteer subjects

EMBS 2008 19


ad