CardioLab Content Introduction Objectives Cardiov. System Cardiov. System Virtual Lab. Virtual Lab. Conclusions CARDIOLAB: A VIRTUAL LABORATORY FOR THE

CardioLabContentContent IntroductionIntroduction ObjectivesObjectives Cardiov. SystemCardiov. System Virtual Lab.Virtual Lab. ConclusionsConclusions

CARDIOLAB: A VIRTUAL LABORATORY FOR THE CARDIOLAB: A VIRTUAL LABORATORY FOR THE

ANALYSIS OF HUMAN CIRCULATORY SYSTEMANALYSIS OF HUMAN CIRCULATORY SYSTEMAlher Mauricio HernandezAlher Mauricio Hernandez11, Gino Pierfranco Herrera, Gino Pierfranco Herrera11, Miguel Angel Mañanas, Miguel Angel Mañanas22, Ramon , Ramon

Costa-CastellóCosta-Castelló33

1 Bioelectronics and Clinical Engineering Research (GIBIC), Universidad de Antioquia (UdeA), Colombia2 Department of Automatic Control (ESAII), Biomedical Engineering Research Center (CREB)

3 Institute of Industrial and Control Engineering (IOC), Universitat Polit`ecnica de Catalunya (UPC), Spain

I O C I n s t i t u t e o f I n d u s t r i a l a n d C o n t r o l E n g i n e e r i n g

GIBIC Bioelectronic and Clinical Engineering


I.I. IntroductionIntroduction

II.II. ObjectivesObjectives

III.III. The Cardiovascular SystemThe Cardiovascular System• Model descriptionModel description

• Cardiovascular stimuliCardiovascular stimuli

IV.IV. Virtual Lab DescriptionVirtual Lab Description • Tool developmentTool development

• Interactive elementsInteractive elements

• Plots and examplesPlots and examples

V.V. ConclusionsConclusions

Co

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ObjectivesObjectives Cardiov. SystemCardiov. System Virtual Lab.Virtual Lab. ConclusionsConclusions


Christian Darkin / Science Photo Library ®

Intr

od

uct

ion

Biomedical Engineering (BME) is the application of engineering sciences and technology to medicine and biology. The interdisciplinary nature of this activity implies interplay and overlapping of interest and effort between engineering and biologic points of view.

Engineers do not need a deep knowledge of certain medical topics (and vice versa).

BME is different to other engineering areas in the sense of obtaining results from experimental procedures and reproducing real physiological situations.


Intr

od

uct

ion

It is very difficult and expensive to interact with the human being body and even dangerous in certain situations.

The field of BME includes many career areas, and one of them is the application of engineering system analysis (physiologic modeling, simulation, and control) to biologic problems.

The Autonomic Nervous system interacts with the cardiovascular system in order to control the heart rate and force of heart contraction, constriction and dilatation of blood vessels.

BSIP, VILLAREAL/ Science Photo Library ®

Roger Harris/Science Photo Library ®


Ob

ject

ives

• Developing a virtual laboratory to study the

cardiovascular system and the effect of stimuli

applied to the autonomic nerve system.

• Proposing the use of Virtual Labs in the study

of cardiovascular system in BME programs, in

order to overcome the drawbacks of interaction

with human body.

• Designing a Virtual Lab in a visually attractive

and interactive way.


Th

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1. Model Description (I)1. Model Description (I)The cardiovascular system is structured in different intermediate processes:

β-SympatheticResponse

ParasympatheticResponse

Basal Heart PeriodFromAutonomicControl

ABPVascularResistance

Change

αTPR CirculatoryMechanics

HeartPeriod COHeart Rate

SV

StrokeVolume

S.A Node

ftbs

ftas

ftp

Ppl

+

+

+

+

+

1/in

Ursino [1998] and Cavalcanti and Belardinelli [1996]


The central autonomic control determines the total α-sympathetic,

ftas, β-sympathetic, ftbs, and parasympathetic, ftp, influences on heart

rate and peripheral resistance from the baroreflexes, chemoreflexes

and lung stretch receptors reflexes.

1. Model Description (II)1. Model Description (II)

Th

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iova

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Sys

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Change



SV

StrokeVolume

S.A Node

ftbs

ftas

ftp

Ppl

+

+

+

+

+

1/in

Autonomic control

afferent signals, ftas,

ftbs and ftp allow

simulation of different

stimuli related with the

sympathetic and

parasympathetic

systems.


Sino Auricular Node (S.A.) translates changes in α-sympathetic, and

parasympathetic, efferent activity into changes in Heart Period (HP):

1. Model Description (III)1. Model Description (III)

Th

e C

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Change



SV

StrokeVolume

S.A Node

ftbs

ftas

ftp

Ppl

+

+

+

+

+

1/in

0.58s






Change



SV

StrokeVolume

S.A Node

ftbs

ftas

ftp

Ppl

+

+

+

+

+

1/in

The α-sympathetic nerves control the peripheral vascular activities.

During hypotension or hypertension, vasoconstriction or

vasodilatation occurs to prevent further decreasing or increasing in

the blood pressure.

1. Model Description (IV)1. Model Description (IV)

Th

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This subsystem is modeled using a first-order dynamic system:






Change



SV

StrokeVolume

S.A Node

ftbs

ftas

ftp

Ppl

+

+

+

+

+

1/in

The stroke volume and the heart period determine the cardiac output (CO) whereas arterial blood pressure (abp) is modulated by the vasculature and cardiac output.

The model determines abp by means of the following expression:

1. Model Description (V)1. Model Description (V)

Th

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Where Cart represents the Arterial Compliance and RTPR the Total Peripheral Resistance.

The stroke volume (SV) is determined by the venous return (Vn), the heart period and the heart contractility (Cn)


1. Cardiovascular Stimuli (I)1. Cardiovascular Stimuli (I)

Exercise: Heart rate (HR) and stroke volume (SV ) increase during exercise, which produces an increase in cardiac output.

Cholinergic intoxication: Produces one increase of parasympathetic activity and produces also an increase of the cardiac period and hypotension.

Caffeine: Xanthines such as caffeine and theophylline block adenosine receptors increasing the activity that produces vasoconstriction, higher heart rate and increased heart contraction force.

Hemorrhage: An acute blood volume loss (10% of total or more), modifies the systemic arterial pressure, cardiac output and total systemic resistance.

Panic: The autonomic system switched to an alert situation characterized by higher and sympathetic activity.

Almost every process that affects the autonomic control system also affects the cardiovascular system through the vagal and sympathetic activity. Five stimuli are considered in Cardiolab:

Th

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Vir

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Des

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n1. Tool Development1. Tool Development

Presented softwarePresented software application application is based on Easy Java is based on Easy Java

Simulations (EJS),Simulations (EJS), an an open sourceopen source java-based tool that java-based tool that allowsallows

creating creating interactiveinteractive dynamic simulations. dynamic simulations.

SIMULINKSIMULINKModel (Ursino et al., 1998)

EASY JAVAEASY JAVA• The model is based on

MATLAB/Simulink®.

• The simulation runs in

Simulink while is controlled

by Easy Java.

• The interface to the user has

been designed and

implemented in EJS.


Vir

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n2. Interactive Elements (I)2. Interactive Elements (I)In the interactive moduleIn the interactive module parameters can be changed by means parameters can be changed by means

of of sliderssliders and and tabstabs in order to in order to simulate different ventilatory simulate different ventilatory

conditions.conditions.

A A multisignal scopemultisignal scope can be seen when this option is can be seen when this option is selectedselected by by

the the useruser..


Vir

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n2. Interactive Elements (II)2. Interactive Elements (II)

From Autonomic

Control


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n3. Plots and Examples (I)3. Plots and Examples (I)One of the One of the two kinds of plotstwo kinds of plots are shown are shown whenwhen the the corresponding tabcorresponding tab of of

signal scopesignal scope is selected by the user: is selected by the user:

A change fromA change from normal conditions (Toxicity Level = 0mg) normal conditions (Toxicity Level = 0mg) to a specific to a specific

amount of amount of pesticides in contact with the human pesticides in contact with the human body (Toxicity Level = body (Toxicity Level =

5mg) is produced 5mg) is produced at 60 seconds at 60 seconds in order to simulate a in order to simulate a cholinergic cholinergic

intoxication.intoxication.


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n3. Plots and Examples (II)3. Plots and Examples (II)After cholinergic intoxication begins, After cholinergic intoxication begins, blood pressure and cardiac output blood pressure and cardiac output

remain in a lightly lower value remain in a lightly lower value (see the figure on the right).(see the figure on the right).

In order to simulate the treatment In order to simulate the treatment of this intoxication, of this intoxication, a second stimulus a second stimulus

is applied at 180s: is applied at 180s: the concentration of the concentration of pesticides = 0 pesticides = 0 and the and the gain of the gain of the

parasympathetic systemparasympathetic system is eliminated in order to is eliminated in order to produce a blockade produce a blockade

(gain = 0)(gain = 0) related with the related with the AtropineAtropine administration. administration.


Vir

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n4. Cardiolab Demo4. Cardiolab Demo


Co

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s• This laboratory is completely This laboratory is completely graphic and interactive,graphic and interactive, so it so it can can

be usedbe used to illustrate to illustrate the behavior of human cardiovascular the behavior of human cardiovascular systemsystem under certain stimuli under certain stimuli..

• CardioLabCardioLab allows the students and researchers allows the students and researchers obtain obtain sensations and experiencesensations and experience that that would be very difficultwould be very difficult otherwise because of the otherwise because of the difficulties in performingdifficulties in performing experimental human studies.experimental human studies.

• The useThe use of virtual laboratories and interactivity in of virtual laboratories and interactivity in BMEBME has has proved to be an proved to be an efficient way to shortcutefficient way to shortcut the the learning process learning process an improve the students capabilities.an improve the students capabilities.

• The toolThe tool has been built combining has been built combining MATLAB/Simulink MATLAB/Simulink and and EJS.EJS. While While MATLAB/Simulink MATLAB/Simulink allows to implement allows to implement complex modelscomplex models in straightforward manner, in straightforward manner, EJS allows to design attractive EJS allows to design attractive viewsviews and and introduce interactivity easily. introduce interactivity easily.

Documents

CardioLab Content Introduction Objectives Cardiov. System Cardiov. System Virtual Lab. Virtual Lab. Conclusions CARDIOLAB: A VIRTUAL LABORATORY FOR THE