pwv & pwa parameter extraction / transfer function
DESCRIPTION
PWV & PWA Parameter Extraction / Transfer Function. Sensors. PWV. Transfer Function. Parameter Extraction. Femoral. PWA. Dorsalis. Carotid. Radial. Diagnosing Cardiovascular Disease. Pulse waves from superficial arteries. Diagnosis of vascular Disease using pulse waves. - PowerPoint PPT PresentationTRANSCRIPT
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PWV & PWA
Parameter Extraction / Transfer
Function
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Dorsalis
Carotid
Radial
Femoral
Pulse waves from superficial arteries
Different shapes of waveforms
PWV
PWA
Diagnosis of vascular Disease using pulse waves
Diagnosing Cardiovascular Disease
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Old stiff aorta
Young normal aorta
- flow wave : flow of the blood itself - doppler
- diameter wave : diameter change (volume change) of the artery – Infrared
- pressure wave : waveform through the arterial wall – pressure sensor
PWV (Pulse Wave Velocity)
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High PWV reflects arterial agingcaused by decreasing arterial elasticity and increasing systolic pressure
High PWV reflects arterial agingcaused by decreasing arterial elasticity and increasing systolic pressure
PWV (Pulse Wave Velocity)
: Velocities of Pulse waves traveling through the arterial wall between two
recording sites provides useful noninvasive index for diagnosing arterial aging and stiffness
PTT2PTT1
Distance
PTT1
PWV =
ECG Electrode
PCG Sensor
Femoral artery
Dorsalis Pedis artery
Carotid artery
Radial artery
PWV (Pulse Wave Velocity)
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Algorithm for detecting upstroke point
– Assign threshold
– 1st differential maximum amplitude
– 2nd differential maximum amplitude
– intersecting tangent method
Feature Extraction
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Patient’s DB
PWV values
Feature extraction
Calculation of PWV Values
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A Study for the comparison of newly developed medicines
• Atenolol/Bendroflumethiazide vs. Amlodipine/Perindopril
• New medicine reduced the fatal and non-fatal Stroke up to 23%
• New medicine reduced the death rate caused by cardiovascular disease and
myocardial infarction up to 16%
• However, there were no differences in the Brachial Blood Pressure values
CAFE
(conduit artery function evaluation)
ASCOT
(Anglo-Scandinavian Cardiac Outcomes Trial)
Importance of Central Blood Pressure
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forward wavefrom the heart reflected
from bifurcation
Forward and Reflected Pressure Pulse
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Resistanceartery
Central Aortic Pulse (Young Elastic Artery)
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Resistanceartery
Central Aortic Pulse (Old Stiff Artery)
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• Increased Left Ventricular Load (LV)
• The area under the pressure-time curve during systole is by definition of LV load
• Increase in LV load accelerates increase in LV mass and increases risk of LV hypertrophy
• Reducing the Coronary Artery Pressure
• The pressure that is perfusing the coronary arteries during the
critical diastole period is reduced
• increasing the risk of myocardial ischemias
(mm
Hg
)
0 100 200 300 400 500 600 700 800 900 1000
Aortic
Systole Diastole(msec)
70
80
90
100
110
120
130
140
150
(mm
Hg
)
0 100 200 300 400 500 600 700 800 900 1000
Aortic
Systole Diastole(msec)
70
80
90
100
110
120
130
140
150
Central Aortic Pulse
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• Definition : Aix(%) = AG/PP*100
• Algorithm : Augmentation Index is defined as the first zero
crossing from positive to negative of the fourth derivative and occurs 55ms after onset of systolic pressure
AG : Augmentation
PP : Pulse Pressure
AIx (Augmentation Index)
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Negative slope and zero-crossing55msec after the upstroke point
Extraction of AIx Point
4th Derivatives
a: systolic peakb: augmentation pointd: dicrotic notch
1st Derivatives after the systolic peak
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Clinical Evaluation
Transfer Function
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Data Select Model
Characterization
Modeling
Verification/Validation
Applications
System Characterization & ARX Model
General-linear polynomial model
ARX model
)(),()(),()( 11 neqHnuqGqny k
),(),(
),(),( 1
qFqA
qBqG
),(),(
),(),( 1
qDqA
qCqH
1)()()( qFqDqC
)()()()()()()()( neknuqBnenuqBqnyqA k
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RADI pressure wire
Analysis systemSBP
PP
Clinical Evaluation