pwv & pwa parameter extraction / transfer function
TRANSCRIPT
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
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)
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)
Algorithm for detecting upstroke point
– Assign threshold
– 1st differential maximum amplitude
– 2nd differential maximum amplitude
– intersecting tangent method
Feature Extraction
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
• 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
• 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)
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
Data Select Model
Characterization
Modeling
Verification/Validation
Applications
System Characterization & ARX Model
General-linear polynomial model
ARX model
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