Cardiovascular system model CVS Active contraction R mt R av R tc R pv R sys R pul Hemodynamics Flow through the vessels Volume variation Cardiac valves mitral tricuspid aortic and pulmonary ID: 578054
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Slide1
Sarah KostaSlide2
Cardiovascular system model (CVS)
Active
contraction
R
mt
R
av
R
tc
R
pv
Rsys
R
pulSlide3
Hemodynamics
Flow through the vessels
Volume variation
Cardiac valves
(mitral, tricuspid, aortic and pulmonary)
= unidirectionnality of the blood flowSlide4
Pressure-volume relationship :
Passive chamber :
Active chamber (both ventricles) :
elastance of the chamber
Varying-elastance model
Input function
HemodynamicsSlide5
Cardiac contraction
From macroscopic to microscopic scale
From microscopic to macroscopic properties: Franck-Starling law
Shiels, H. a & White, E. The Frank-Starling mechanism in vertebrate cardiac myocytes.
J. Exp. Biol.
211,
2005–2013 (2008).
Adapted from Klabunde
, R. (2011). Cardiovascular physiology concepts. Lippincott Williams & Wilkins.Slide6
Modeling cardiac contraction
Varying elastance model cell-based model
Cardiac cell
Sarcomere contraction
Calcium release from the sarcoplasmic reticulum
Electrical stimulation (action potential) Slide7
Varying elastance model cell-based model
Electrophysiological
model
(
ten
Tusscher & Panfilov
2006)
Mechanical model
(
Negroni & Lascano
2008)
Modeling cardiac contractionSlide8
E
lectrophysiology
Time (ms)
Intracellular calcium (µM)Slide9
Sarcomere contraction
e
lastic length
inextensible
length Slide10
e
lastic length
inextensible
length
sliding velocity
= steady elongation
Sarcomere contraction
Slide11
Excitation-contraction coupling
,
Slide12
From cell to organ
Both ventricles are assimilated to simple spheres and the pressure and volume can be related to the force and half-sarcomere length:
Shim, E. B., Amano, A., Takahata, T., Shimayoshi, T. & Noma, A. The cross-bridge dynamics during ventricular contraction predicted by coupling the cardiac cell model with a circulation model.
J Physiol Sci
57,
275–285 (2007).
half-sarcomeres are aligned along a circle of radius
:
Blood volume inside the ventricular cavity is given by:
and
are related by:
and
are linked
The wall stress
is considered constant and is related to the pressure inside the ventricular cavity:
The wall stress is also related to the normalized force
given by the sarcomere model:
and
are linked
Slide13
Results :
Baseline
Cardiovascular system model (CVS)Slide14
Results :
Fogarty balloon
Cardiovascular system model (CVS)
P
lv
V
lv
Left V.
P
ao
V
ao
Aorta
P
vc
V
vc
Vena cava
P
rv VrvRight V.
P
pa
V
pa
Pul. Art.
P
pu
V
pu
Pul. V.
R
mt
R
av
R
tc
R
pv
R
sys
R
pul
Active
contractionSlide15
Results :
Fogarty balloon
Cardiovascular system model (CVS)
P
lv
V
lv
Left V.
P
ao
V
ao
Aorta
P
vc
V
vc
Vena cava
P
rv VrvRight V.
P
pa
V
pa
Pul. Art.
P
pu
V
pu
Pul. V.
R
mt
R
av
R
tc
R
pv
R
sys
R
pul
Active
contractionSlide16
Results :
Ventricular failure
Cardiovascular system model (CVS)Slide17
Future perspectives:
Fluid therapy: « Will a patient be fluid responsive ? »
-> Need for indicators of fluid responsiveness
Cardiovascular system model (CVS)Slide18
Future perspectives:
Fluid therapy: « Will a patient be fluid responsive ? »
-> Need for indicators of fluid responsiveness
Contractility index: « What is the
contractile
state of a
patient’s heart ? » -> Need for a contractility index that is not load dependent (and preferably available
with non-invasive measures)-> comparison of different proposed indices
Cardiovascular system model (CVS)