MATLAB AND CARDIOVASCULAR ENGINEERING

SOLVING PROBLEMS, SAVING TIME

Dr Michael Stevens

INNOVATIVE CARDIOVASCULAR ENGINEERING AND TECHNOLOGY LABORATORY

Using MATLAB in the ICET LAB

• Numerical Model (Computer Simulation)

• Mock Circulation Loop (Mechanical Simulation)

• Design and Tuning of Feedback Control Loops

1. Terracciano, C.M., L.W. Miller, and M.H. Yacoub, Contemporary use of ventricular assist devices. Annu. Rev. Med., 2010. 61: p. 255-70.2. Heidenreich, P.A., et al., Forecasting the Future of Cardiovascular Disease in the United States: A Policy Statement From the American Heart Association. Circulation, 2011. 123(8): p. 933-944.3. Thunberg, C.A., et al., Ventricular assist devices today and tomorrow. Journal of Cardiothoracic and Vascular Anesthesia, 2010. In Press.

• Prevalence: About 3% of population1,2

• Hospital admissions: Over 1M in US alone per year3

• Costs: $35B USD per year in US2

• Projections: $95B USD per year in US by 2030.2

• Less than 4000 heart transplants performed worldwide per year.

HEART FAILURE

Ventricular Assist Devices - VADs

• Bridge to transplantation

• Bridge to destination

Rise of VAD implantations

About The ICET LabThe Prince Charles Hospital

Combating cardiovascular disease by serving as a bridge between the engineering department and clinic.

ICET LAB - OUR AIM

Using MATLAB in the ICET LAB

• Numerical Model (Computer Simulation)

• Mock Circulation Loop (Mechanical Simulation)

• Design and Tuning of Feedback Control Loops

Testing VADs

High CostLow repeatabilityRequires proof of

concept

Low CostHigh repeatability

Numerical Model – Lumped Parameter Model

• Developed Dr Einly Lim – University of Malaya

Simulink Model – Cardiovascular System

• Created by PhD Student Frank Nestler

Simulink Model – Pump and Cannula

Validation – Left Ventricular Pressure

Literature Numerical Model

Using MATLAB in the ICET LAB

• Numerical Model (Computer Simulation)

• Mock Circulation Loop (Mechanical Simulation)

• Design and Tuning of Feedback Control Loops

Mock Circulation Loop

Instrumentation and Actuation

P

V

Q

PV

S&R

P

PP P

P

P

P

P

P

V

Q

Q

Q

PV

S&RS&R

16+ Analog inputs5+ Digital outputs7+ Analog OutputsControl @ 2000HzSample @ 100 Hz

S&R

S&R

Simulink Control Model for MCL

Controlling MCL with MATLAB and dSPACE

Simulink Model

dSpace Processor

Compile

DA out

AD in

Mock Circulation Loop In Action

MCL Validation Literature

MCL

Numerical Model

MCL Additions – Cerebral Circulation

Literature

Numerical Model

Using MATLAB in the ICET LAB

• Numerical Model (Computer Simulation)

• Mock Circulation Loop (Mechanical Simulation)

• Design and Tuning of Feedback Control Loops

Physiological Control:‘Smart’ Cruise Control for Rotary VADs

Automatically adjust speed to respond to physiological changes• Prevent collapse of ventricle

• Increase flow during exercise

Control System Tuning

• Very complex plant model

• High-order

• Non-linear

• Time and patient variance

• Tuning was performed using gradient descent optimisation.

• Initially developed own optimisation script

• Now use MATLAB Optimisation Toolbox

Optimisation Objective Function

Define Ideal Control + Plant

Behaviour

𝜔𝑛2

𝑠2 + 2ζ𝜔𝑛𝑠 + 𝜔𝑛2

+

- 0

𝑇Value to minimise

𝑥2

C(s) G(s)+-

Controller Plant

Target

Rise TimeSettling TimeOvershoot

Optimising to achieve an ideal response

Control Tuning using Optimisation: Some Considerations.

• Local vs. Global minima.

• Initial Guess of Gains.

• Requires careful selection of objective function and optimisation parameters.

• MATLAB documentation for Optimisation Toolbox very helpful.

Using MATLAB in the ICET LAB

• Numerical Model (Computer Simulation)

• Mock Circulation Loop (Mechanical Simulation)

• Design and Tuning of Feedback Control Loops

Solving Problems, saving time

Thank you