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Blood flow monitoring incerebral vessels
A. P. ChupakhinLavrentyev Institute of Hydrodynamics, Novosibirsk, Russia
Novosibirsk State University
In collaboration with
A. A. Cherevko, A. K. Khe(Lavrentyev Institute of Hydrodynamics, Novosibirsk State University)
A. L. Krivoshapkin, K. Yu. Orlov(Meshalkin Novosibirsk Research Institute of Circulation Pathology)
IV International Workshop on the Multiscale Methods and Modelling in Biology and MedicineOctober 29–31, 2014, Moscow, Russia
Cerebral hemodynamics
Hemodynamics is a hydrodynamics of fluid with various inclusions in a complex net of vessels with walls of different properties.• Blood rheology: leucocytes, erythrocytes,
etc.• Wall properties: elasticity, fluid–structure
interaction.• Vessel net: branching, junction.
A human brain:• is of mass ≈ 1.5% mass of the body,• uses ≈ 20% blood and oxygen.
Characteristic flow parameters:• Pulsatile flow• Velocity: 20–200 cm/s• Pressure: 20–150 mm Hg• Viscosity: 4 cP• Vessel diameter: 0.5–5 mm• Vessel length: 100 cm• Re: ≤ 100
Mathematical modeling
Models:• Electric circuit, hydraulic analogy, balance relations, 1D gas dynamics,• Navier—Stokes equations, flows in elastic tubes, etc.• Local modeling: direct 3D computations.• Hemodynamics on a graph.
Problems:• Obtaining reliable measurement data: there is no unique or “standard”
circulation configuration, there is no possibility to take measurements precise enough in vivo.• Mathematical modeling: construction of models consistent with the data
obtained, definition of boundary conditions.
Arterial aneurysms (AA)
An aneurysm is a localized, blood-filled balloon-like bulge in the wall of a blood vessel.
Arteriovenous malformation (AVM)Arteriovenous malformation (AVM)is a direct connection betweenarteries and veins, without capillarysystem, which leads to inadequateblood supply, change of velocity andpressure profiles, tortuosity of vessels.
Treatment: Endovascular surgery—embolization
AVM: Onyx, Histoacryl AA: coils, stents
How it started
• Why can operations, that are visually similar, differ in results?
• What is the difference between them?
• How to measure this “difference”?
• Does the disease need to be treated? When and how?
• Does the operation really help the patient?
The aim
Complex investigation of pathological cerebral vessels of human: clinical and physiological analysis, mathematical and computer modeling, in order to develop new methods for diagnostics, prognosis and treatment.
MEASUREMENTS
MRI, CT, angiography
Diameters
Lengths
Pressure and Doppler ultrasonography measurement system
A pressure and velocity measurement sensor: diameter ≈ 0.36 mm, length ≈ 1.2 m.
Arteriovenous malformation of left temporal lobe.
Partial embolization
Operative report
• Duration: 9:00 – 11:00• Operation progress:– Measurements: arteries– Embolization of fistulae (Histoacryl, 2 ml)– Measurements: draining vein– Measurements: sinuses– Measurements: arteries
Description
• Arteriovenous malformation of mixed type (fistula component, intranidal aneurysms), located in left temporal lobe, Spetzler–Martin II grade
• Size: 33,5 х 22,5 х 25 mm.• Afferents: M3, М4 segments.• Drainage: dilated vein into left transverse sinus,
sagittal sinus.
Angiography. Frontal projectionBefore operation After operation
Angiography. Lateral projectionAfter operationBefore operation
Measurements: Arteries
BeforeAfter
Measurements: Draining vein
BeforeAfter
Duringoperation
Measurements: Sinuses
Measurements were taken after the operation
COMPARISONSEssential hemodynamic parameters
Arteries.Before the operation
BeforeAfter
12
3
4
5
6
7
2 4 6 8
2
4
6
8
12
34
5 6
7
20 40 60 80 100 120 140
10
20
30
40
50
60
70
V-P
Q-E
1
23
4
1 2 3 4 5 6
1
2
3
4
5
6
1
234
2 0 4 0 6 0 8 0 1 0 0 1 2 0
2 0
4 0
6 0Arteries.After the operation
BeforeAfter
V-P
Q-E
Parameters in arteries
09 :29 :52 09 :30 :01 09 :30 :10 09 :30 :19 09 :30 :28 09 :30 :37
405060708090
P res s ure, mm Hg
10 :55 :06 10 :55 :16 10 :55 :27 10 :55 :37 10 :55 :48 10 :55 :58
405060708090
P res s ure, mm Hg
09 :29 :52 09 :30 :01 09 :30 :10 09 :30 :19 09 :30 :28 09 :30 :37
6080100120140160180
Velo c ity, cms
10 :55 :06 10 :55 :16 10 :55 :27 10 :55 :37 10 :55 :48 10 :55 :58
6080100120140160180
Velo c ity, cms
Before the operation After the operation
09 :31 :00 09 :31 :13 09 :31 :26 09 :31 :39 09 :31 :52 09 :32 :04
405060708090
P res s ure, mm Hg
10 :57 :38 10 :57 :53 10 :58 :08 10 :58 :24 10 :58 :39 10 :58 :54
405060708090
P res s ure, mm Hg
09 :31 :00 09 :31 :13 09 :31 :26 09 :31 :39 09 :31 :52 09 :32 :04
10
20
30
40
50Velo c ity, cms
10 :57 :38 10 :57 :53 10 :58 :08 10 :58 :24 10 :58 :39 10 :58 :54
10
20
30
40
50Velo c ity, cms
Parameters in arteries
Before the operation After the operation
6
2
74
2 4 6 8
2
4
6
8
6
2
74
20 40 60 80 100 120 140
10
20
30
40
50
60
70
Arteries. Comparison
V-P
Q-E
BeforeAfter
During the operation
10:22:04 10:25:54 10:29:44 10:33:33 10:37:23 10:41:13
0.12
0.13
0.14
0.15
0.16
0.17
0.18P re ssu re
10:22:04 10:25:54 10:29:44 10:33:33 10:37:23 10:41:13
0.15
0.20
0.25
0.30
0.35Velo c ity
BeforeAfter
During the operation
Histoacryl ????? Histoacryl
12
3
5 10 15 20 25 30
5
10
15
Operation
1
2
3
1 2 3 4 5 6 7
0 .5
1 .0
1 .5
V–P
Q–E
Velocity and flow rate drop ≈ 39%
Pressure drop ≈ 12%
Sinuses1 2
3
45
67
8
9
10 20 30 40 50 60
5
10
15
1
2
3
4
56
7
89
2 4 6 8 10
0.5
1 .0
1 .5
2 .0
2 .5
3 .0
V-P
Q-E
Pressure and velocity in sinuses
Pressure Velocity
10 :45 :42 10 :45 :46 10 :45 :50 10 :45 :54 10 :45 :58
0.145
0.150
0.155
0.160
0.165
0.170P res s ure
10 :45 :42 10 :45 :46 10 :45 :50 10 :45 :54 10 :45 :58
0.05
0.10
0.15
0.20
Velo c ity
Novelty
• For the first time simultaneous pressure and velocity invasive measurements in feeding and draining vessels of AVM are taken.
• Qualitative changes in local hemodynamics during the embolization are shown.
• Experimental data are justified by AVM hydraulic model.
• The data obtained are used to propose principles of the most harmless endovascular treatment of cerebral AVMs.
Main hemodynamic parameters
• — Volumetric flow rate• — Total pressure • — Energy flow rate• — Load• — Specific load
– is energy transferred into AVM– is energy transferred out of AVM
Q vS2 2P p vαρ
E QP
1 2W E E
w W V
1E
2E
Hydraulic model of AVM
l, d — length and diameter of tubes
AVM
Dependence on the level of the AVM embolization
0
20
40
60
80
100
120
140
0 20 40 60 80 100
Pressure
пациент И
пациент К
пациент Т
Пациент С
0
10
20
30
40
50
60
70
80
0 20 40 60 80 100
Velocity
пациент И
пациент К
пациент Т
пациент С
0
0,5
1
1,5
2
2,5
3
3,5
4
0 20 40 60 80 100
Load
пациент И
пациент К
пациент Т
пациент С
0
1
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8
0 20 40 60 80 100
Specific load
пациент И
пациент К
пациент Т
пациент С
mm Hg
cJ cJ/cm3
cm/s
Dependence on the level of the AVM embolization
0
20
40
60
80
100
120
140
0 20 40 60 80 100
Pressure
пациент И
пациент К
пациент Т
Пациент С
0
10
20
30
40
50
60
70
80
0 20 40 60 80 100
Velocity
пациент И
пациент К
пациент Т
пациент С
0
0,5
1
1,5
2
2,5
3
3,5
4
0 20 40 60 80 100
Load
пациент И
пациент К
пациент Т
пациент С
0
1
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8
0 20 40 60 80 100
Specific load
пациент И
пациент К
пациент Т
пациент С
mm Hg
cJ
cJ/cm3
cm/sSpecific load
Group treatment statistics
Research group Comparison
group
Number of patients 30 94
Number of embolization sessions 34 176
Hemorrhagic complication (hemodynamic, without manipulative) 1 11
% of hemorrhagic complications per patients 3,3% 11,7%Incapacitation as a result of perioperative hemorrhage 0 4 (4,25%)
Lethality 0 1 (0,78%)
Z = 2,039; p<0,05
Thank you for your attention!