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

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0 20 40 60 80 100

Velocity

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Load

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Specific load

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mm Hg

cJ cJ/cm3

cm/s

Dependence on the level of the AVM embolization

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0 20 40 60 80 100

Pressure

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Velocity

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Specific load

пациент И

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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!