Development of Mock Circulatory System and Cardiovascular Parameters John Marshall Dr. Gerald Miller Charles Taylor VCU Biomedical Engineering

Development of Mock Circulatory System and Cardiovascular

Parameters

John MarshallDr. Gerald MillerCharles TaylorVCU Biomedical Engineering

Why is this important?!•What is congestive heart failure?

•How many donor hearts are available each year?

•How many death’s per year?

• How much is it costing the U.S.?

• How many patients need a donor heart?

Inadequate distribute of blood

OVER 300,000 in the U.S.!

Estimated less than 2,000!

100,000 need donor hearts

$35 billion in the United States

Ventricular Assist Pumps (VAD’s)

•Bridge to recovery

•Bridge to transplantation

•How’s it help?

•How’s it work?

pump blood through circulatory system

restore the patient’s cardiac output

waiting for a donor heart to become available

allowing the heart muscle to rest and heal

promote tissue and functional recovery

Left Ventricle

Aorta

Testing Using the Mock Circulatory System

•Why is this important???•Food and Drug

AdministrationRequired before moving to animal and human trials

$$$$

•Why not go straight to animal trials?

evaluate the hemodynamics

refine VAD designs

Mock Circulatory System

Harvard Pump

Compliance Chamber

Resistor

Venous Reservoir

LVAD

•Components

•Purpose?

Harvard Pump•Why is it used?

•What can it do?

•What is being pumped?

Harvard Pump

Gold standardPulsatile

stroke volume

Heart rate

time in systole

Blood analog 40% glycerin, 60% waterMimics viscosity and density properties

Harvard Pump

Compliance Chamber

•Purpose?

Compliance ChamberPulse wave dampening

•How’s it work?

mimics the elasticity of the arteries

Dispersion force

Compliance Chamber

Resistor

•What does it do?

•How does it work?

Resistor

simulate peripheral resistance

friction between the blood and the walls of blood vessels

Motor compresses plates

Adjust cross sectional circumference

Resistor

Venous Reservoir•Purpose?

Venous Reservoir

•How’s it work?

Smooth delivery of liquid Pressure based on varying volume

Venous Reservoir

Multi-Disk Centrifugal Pump•Design

LVAD•Advantages

5 disks0.063in. thick0.016in. spacing

Connected to a DC motor

Rocket fuel

Smooth ejection

High RPM generates high pressure

Multi-Disk Centrifugal Pump•How does it operate?

1- Fluid enters rotor area2- Fluid enters space between disks

3- Fluid is spun at high speeds

4- Fluid spins off disks into volute chamber

5- Fluid is ejected through outlet

What are we trying to replicate?

The human cardiovascular systemPulmonary circulation

Systemic circulation

Under what conditions?Rest

Exercise

TransitioningPathological

Development of Cardiovascular Parameters

•How did I do this?

“Cardiovascular parameters”“Postural changes affecting blood pressure”“Cardiac output during exercise”“Mock circulatory system”

What was I looking For?

•Heart rate- beats per minute- (cardiac cycle/60x1000)¯¹

Which parameters are necessary?

•Stroke volume- amount of blood pump in one contraction- CO/HR*1000

•Cardiac output- volume of blood pumped per minute- HR * SV/1000

•Systolic pressure- heart contracting•Diastolic pressure- heart relaxing•Time is systole- % heart contraction-

Ejection duration/cardiac cycle•Peripheral resistance- opposition

encountered by blood flow- ((MAP-CVP)* 80) / (CO)











































Cardiovascular responses to postural changes: differences with age for women and men.

T (s)

HR (bpm)

SV (ml/beat)

MSER (mL x sec¯¹)

CO(1 x min¯¹)

SP (mm Hg)

DP (mm Hg)

Systole (%) Sex

Postural Pos.

Head Angle (Degrees)

Condition

Activity

VAD

Mean Age

Predecessor

Reference

1300 58.7 118 379 120 77 Male supine 0Healthy Rest N21-59 0

Frey MA.

2300 66.5 82 26 108 70 Femalesupine 0Healthy Rest N21-59 0

Frey MA.

3300 65.9 87 314 120 82 Male sit 90Healthy Rest N21-59 1

Frey MA.

4300 70 62 212 111 76 Femalesit 90Healthy Rest N21-59 2

Frey MA.

5300 72.3 72 296 119 84 Male stand 90Healthy Rest N21-59 3

Frey MA.

6300 81.8 48 195 110 78 Femalestand 90Healthy Rest N21-59 4

Frey MA.

Cardiac output= (58.7 x 118)/ 1000 = 6.9

Cardiac output= (HR x SV)/ 1000

T (s)

HR (bpm)

SV (ml/beat)

MSER (mL x sec¯¹)

CO(1 x min¯¹)

SP (mm Hg)

DP (mm Hg)

Systole (%) Sex

Postural Pos.


Condition

Activity

VAD

Mean Age

Predecessor Reference

1300 58.7 118 379 6.9 120 77 Male supine 0Healthy Rest N21-59 0Frey MA.

2300 66.5 82 26 5.4 108 70 Femalesupine 0Healthy Rest N21-59 0Frey MA.

3300 65.9 87 314 5.7 120 82 Male sit 90Healthy Rest N21-59 1Frey MA.

4300 70 62 212 4.3 111 76 Femalesit 90Healthy Rest N21-59 2Frey MA.

5300 72.3 72 296 5.2 119 84 Malestanding 90Healthy Rest N

21-59 3Frey MA.

6300 81.8 48 195 4 110 78 Femalestanding 90Healthy Rest N

21-59 4Frey MA.

Time in systole= Ejection duration/cardiac cycle

Mean Stroke Ejection Rate= Stroke Volume/ Ejection DurationEjection Duration= Stroke Volume/ MSER

Ejection Duration= 118/ 379= 0.311

Time in systole= (0.311/ 1) x 100 = 31.1%

Cardiovascular responses to postural changes: differences with age for women and men.

T (s)

HR (bpm)

SV (ml/beat)

MSER (mL x sec¯¹)

CO(1 x min¯¹)

SP (mm Hg)

DP (mm Hg)

Systole (%) Sex

Postural Pos.


Condition

Activity

VAD

Mean Age

Predecessor Reference

1300 58.7 118 379 6.9 120 77 31.1Male supine 0Healthy Rest N21-59 0Frey MA.

2300 66.5 82 26 5.4 108 70 31.5Femalesupine 0Healthy Rest N21-59 0Frey MA.

3300 65.9 87 314 5.7 120 82 27.8Male sit 90Healthy Rest N21-59 1Frey MA.

4300 70 62 212 4.3 111 76 29.2Femalesit 90Healthy Rest N21-59 2Frey MA.

5300 72.3 72 296 5.2 119 84 24.3Malestanding 90Healthy Rest N

21-59 3Frey MA.

6300 81.8 48 195 4 110 78 24.6Femalestanding 90Healthy Rest N

21-59 4Frey MA.

Physiological responses to postural change in young and old healthy individuals.

T (s)

HR (bpm)

SV (ml/beat)

CO (1 x min¯¹)

SP (mm Hg)

DP (mm Hg) Sex

Postural Pos.


Condition Activity VAD

Mean Age

Predecessor

Reference

7 300 65.5 114.8 7.45 107.2 69.3BothSupine 0Healthy Rest N 31 0Vargas E.






A complete mock circulation loop for the evaluation of left, right, and biventricular assist devices.

Time (s)

Heart Rate (bpm)

Stroke Volume (ml/beat)

Cardiac Output (1 x min¯¹)

Systolic Pressure (mm Hg)

Diastolic Pressure (mm Hg)

Systemic Venous Compliance (mL/mm Hg)

Time in Systole (%)

Left Atrial Pressure (mm Hg)

24 300 60 83.33 5 120 80 22.5 40 925 300 60 41.67 2.5 70 50 11.5 40 20

Left Ventricle Pressure (mm Hg)

Left Ventricle End Diastolic Pressure (mm Hg) Sex

Postural Position


Pathological Condition Activity VAD Used Mean Age

Reference

0-120 8N/A N/A 0 Healthy Rest N N/A Timms D.15-80 20N/A N/A 0 HF Rest N N/A Timms D.

Current status…•Construction is incomplete•Parameter spreadsheet is in progress

Future…• Run developed parameters in completed mock loop

•Confidence level

Thanks for a GREAT summer!

Dr. Gerald Miller for his lab time and resources

Charles Taylor for his time, patience, and guidance

Dr. Jeff Elhai, Sherry Baldwin, and Andy Surface for directing BBSI

National Science Foundation for the grant money!

Documents

Development of Mock Circulatory System and Cardiovascular Parameters John Marshall Dr. Gerald Miller Charles Taylor VCU Biomedical Engineering