1 Theo Arts [email protected]Frits Prinzen, Tammo Delhaas*, Peter Bovendeerd**, J. Lumens, W. Kroon (Biophysics, Physiology, Pediatric Cardiology, Engineering) Maastricht University, *Maastricht University Hospital **University of Technology, Eindhoven The Netherlands IPAM Feb 06 Modeling of heart mechanics with adaptation of tissue to load
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Modeling of heart mechanics with adaptation of tissue to load
Modeling of heart mechanics with adaptation of tissue to load. Theo Arts [email protected] Frits Prinzen, Tammo Delhaas*, Peter Bovendeerd**, J. Lumens, W. Kroon (Biophysics, Physiology, Pediatric Cardiology, Engineering) Maastricht University, *Maastricht University Hospital - PowerPoint PPT Presentation
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- valve with inertiadoppler velocity and accelerationmass ~ dynamic membrane
→ pressure transducer
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Hypertrophy in12 wks myofiber
mechanics in AV-block
Systolic fiber stress is not the stimulus to hypertrophy.
More likely: end-diastolic stress
(Donker et al, Basic Res Cardiol, 2005).
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Adaptation rules with‘deformation intervention’
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fiber direction
torsion
fiber direction
torsion
Situs Solitus(normal)
Situs InversusTotalis (SIT) Hypothesis
SIT heart with mirrored fiber structure is an alternative solution satisfying adaptation rules of cardiac cells.
Test
SIT heart should have equal torsion but in opposite direction.
occurrence
8000 : 1
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Situs Inversus Totalis Normal
(pig SIT heart)
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Situs Solitus (normal) ?? Situs Inversus Totalis ??Torsion (rad)
-0.20 -0.10 0 0.10 0.20
Expected torsion in SIT
NOT TRUE !
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-0.10
0.00
0.10
0.20Rotation
[rad]
-0.20
-0.10
0.00
0.10Torsion
5 base43
2
1 apex
d basecba apex
Situs Solitus(normal)
Situs InversusTotalis (n=14)
0.5 s
Human torsion
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-0.20
Situs Solitus (normal) Situs Inversus Totalis
Torsion (rad)
Torsion in SIT
-0.10 0 0.10 0.20
Delhaas, T. et al. Ann N Y Acad Sci 1015: 190-201.
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Myofiber structure in SITNormal adaptation rules
Start conditions for fiber structure:- normal apex- inverse base
Development to SIT structure
→ RESULT
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Situs Inversus Totalis
A natural in vivo ‘experiment’ to investigate cell’s long term response to a variety of deformations
boundary conditions
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inverse
Dualistic myofiber structure SIT
Helix angleendo - epi
inverse
normal
normal
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Efficency
The structure of the SIT heart is different.
Because each cell optimizes generation of mechanical work (= adaptation rule), all cells work close to their optimum. Since the only escape of mechanical work is pump work, the SIT heart works about just as optimal as the normal heart.
stress-strain work
stress-strain work
stress-strain work
The only escape of work:
pump work (p-V)
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General conclusion: Self-structuring by adaptation
“morphogenetic draft”
result
Self-adaptation until load is proper
growing brick
- works for cardiovascular modeling on all levels- adaptation can be modeled- should be used as prior knowledge in heart modeling