CardioTrack a NEW clinical tool for measuring arterial stiffness

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CardioTrack a NEW clinical tool for measuring
arterial stiffness vascular tone
Presented by Terry Martin, Micro Medical Ltd
? Micro Medical Ltd 2004
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SEDS Reversing Heart Disease

• SEDS Long term intense risk factor modification
• Supported Exercise
• Supported Diet
• Supported Stress Management
• 3 sessions/week _at_ 7,000/person/year
• Results of randomised control trial in 8 centres
• 173 (inc. 34 repeats) cardiac surgery (129) cost
  47,647
• 194 SEDS but 57 went for cardiac surgery
  (29) cost 18,119
• Dean Ornish et.al.Am J Cardiol 199882T72-76

? Prof Paul Johnson, University of Oxford
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?Prof Paul Johnson, University of Oxford
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What is Arterial Stiffness?

• The pressure(work) that needs to be generated in
  order to change the vessel diameter (cm/mmHg).
• The speed of the arterial pulse (Pulse Wave
  Velocity) is related to arterial stiffness
• PWV(carotid/femoral) is the gold standard
  measure for arterial stiffness
• Arterial stiffness is an independent predictor of
  cardio-vascular events and a target for therapy

? Micro Medical Ltd 2004
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Clinical Value of Arterial Stiffness (as
measured by PWV carotid-femoral)

• Arterial stiffness is an independent predictor of
  cardiovascular mortality - Key ref. include
• Diabetic and glucose intolerance patients
• Cruickshank K et al., Circulation 2002
• Elderly patients
• Meaume S et al., Arterioscler Thromb Vasc Biol
  2001
• Hypertensive patients
• Laurent S et al. Hypertension 2001
• ESRD patients
• Blacher J et al., Circulation 1999
• Therapy targeted at reducing stiffness is under
  study
• Mahmud Feely. Cardiovas. Ther. 2003

? Micro Medical Ltd 2004
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Aortic Stiffness (PWVcf) Survival
ESRD patients Blacher et al. Circulation. 1999
? Micro Medical Ltd 2004
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What Are the Barriers Preventing PWV Stiffness
becoming a Routine Measurement?

• Outcome data from a Normal population
• The current tests are time consuming
• They require a trained operator
• The subject needs to be undressed and supine
• An alternative solution is needed
• Pulse Contour Analysis

? Micro Medical Ltd 2004
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What is Pulse Contour Analysis ?

• Pulse Contour Analysis uses the characterisitic
  of the arterial pulse to derive indices related
  to arterial stiffness and arterial tone

? Micro Medical Ltd 2004
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The Arterial Pulse

• The pulse distorts the arterial wall.
• The pulse wave/distortion travels at a speed
  determined by the stiffness/elasticity of the wall

• reflections occur when the vessel changes in
  some way

? Micro Medical Ltd 2004
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The arterial pulse differs in different locations
due to wave propagation and reflections
A good location to measure the arterial pulse is
in a digit where it is easy to access
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The heart expels blood, distorting the arterial
wall to create the arterial pulse. The arterial
pulse start to propagate through the arteries
At the finger, the pulse starts to form.
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When the pulse encounters diameter changes and
arterial bifurcations, it gets reflected back and
a large wave reflection is generated in the lower
torso.
At the finger, the pulse continue to form.
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The reflected wave propagates back up in the
aorta and then in the upper arm.
At the finger, the the reflected pulse starts to
appear.
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The direct wave and the reflected add up together
...
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to form the digital pulse
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Influence of Arterial Stiffness on the Finger
Pulse
Clinical evidence supports this mechanism
? Micro Medical Ltd 2004
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Influence of Arterial Tone (Dia.) on the Finger
Pulse
Clinical evidence supports this mechanism
? Micro Medical Ltd 2004
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A simple method to monitor the Finger Pulse -
Photopletysmography
infra-red transmitter
receiver
? Micro Medical Ltd 2004
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Characteristics of the Digit Volume Pulse (DVP)
PPT related to large artery transit time
digital volume pulse
b
Amplitude related to peripheral vasodilation
a
time
? Micro Medical Ltd 2004
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Local effects
Intra-arterial GTN
Probe 1
FBF
Probe 2
Ratio left/right
RI

• DVP in left and right hand are very similar.
• Local vasodilation causes similar changes in
  both left and right DVPs.

Chowienczyk et al., JACC 1999 Allen et al.,
Physiol. Meas. 2000
? Micro Medical Ltd 2004
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RI is related to vasodilation
GTN 3 ?g/min RI 61
GTN 30 ?g/min RI 49
GTN 300 ?g/min RI 42
Saline RI 76
? Micro Medical Ltd 2004
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Are PPT and SI related to large artery stiffness ?
500
400
300
?TDVP (ms)
R 0.65 P lt 0.0001
200
R0.75
100
0
100
40
50
60
70
80
90
Aortic TT (ms)
Chowienczyk et al., JACC 1999
Millasseau et al., Clin.Sci.2002
? Micro Medical Ltd 2004
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Large artery stiffness is age dependant
PPT
Age 60 yrs PPT 147 ms SI 12.2 m/s
Age 45 yrs PPT 270 ms SI 6.8 m/s
Millasseau et al., Clin.Sci.2002
? Micro Medical Ltd 2004
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Accuracy/Reproducibility
within subject coefficient of variation
Study Reference
1
2, 4
3 inter
3 intra
subject numbers (male/female)
8/0
30/0
13/10
13/10
status
healthy
15 CAD/15 healthy
healthy
healthy
age
young
?/young
54/- 12
54/- 12
PulseTrace SI
9.6
17.8 (15)
14.4
11.9
SphygmoCor Vx Central PWV
8.8
10.5
SphygmoCor Px AI
22.4
PulseTrace RI
7.0
4.8
Sessions
300.0
?
8
investigator(s)
1
1
2
period
2 weeks
?
1 day
number of tests per session
3 every 5min
?
2 separted by 2min
1. Millaseau et al Clinical Science (2002) 103,
371377
rd
2. Woodman et al Poster presentation, 73
EAS 2002
3. Laucevicius et al Seminars in Cardiology,
2004, Vol. 10, No. 2, 83-90
4. Woodman et al Med Sci Monit, 2003 9(5)
RA81-89.
? Micro Medical Ltd 2004
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Factors influencing SI/RI ?

• BP (increasing stiffness)
• Stress
• Fatigue
• Exercise
• Aerobic exercise (vasodilation)
• Isometric exercise (vasoconstriction)
• Smoking (vasoconstriction)
• Food intake
• Alcohol (vasodilation)
• Digestion (gut vessels dilation)
• Fatty food (reduce endothelial activity)

? Micro Medical Ltd 2004
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CardioTrack from CardioCheck

• Sound scientific basis
• It is stable, easy to use
• Provides SI, a measure of large artery stiffness
  which correlates well with the gold standard
  measurement of arterial stiffness and with
  comparable repeatability
• Provides RI, a measure vessel tone which can be
  used to assess endothelial function
• A NEW CLINICAL TOOL

? Micro Medical Ltd 2004
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Thank You

• To learn more go to www.cardiocheck.co.uk or
  www.pulsetrace.com

? Micro Medical Ltd 2004
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Volume and Pressure Waveforms
The digit pressure waveform can be accurately
predicted from the DVP - They both contain the
same information
Millasseau et al Hypertension 2000
? Micro Medical Ltd 2004
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Is SI related to large artery stiffness ?
? Micro Medical Ltd 2004
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Decreasing Stiffness
As the vessel less Stiff the PWV decreases and
the reflected wave takes longer to reach the
finger. This has an impact on the finger wave
shape which is the sum of both the direct and
reflected waves.
Correct location for time markers to measure the
time taken for the reflected wave to reach the
finger
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Decreasing Wave Reflection
As the periphery dilates less energy is reflected
back (Decreasing Wave Reflections) and the
reflected wave reduces in amplitude. This has an
impact on the finger wave shape which is the sum
of both the direct and reflected waves.
A3
A1 gt A2 gt A3
Correct location for time markers to measure the
time taken for the reflected wave to reach the
finger
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Relationship between AIx, SI RI
SI height/PPT
? Micro Medical Ltd 2004