ANALYSIS OF THE BROKEN HEART SYNDROME PROPOSED MECHANISM USING REGIONAL STRESS–STRAIN APPROACH

Mor Marks (1), Jacob Bortman (1), Ronen Beeri (2)

1. Ben-Gurion University of the Negev, Israel; 2. Hadassah Hebrew University Medical Center Heart Institute, Israel

Introduction

Computational approaches to simulate healthy and

diseased hearts have the potential to improve our

understanding of the functioning of the

myocardium and hence to assist in developing

better treatments for cardiac diseases, which

account for significant morbidity and mortality the

world over. Takotsubo Cardiomyopathy (TC), also

known as the Broken Heart Syndrome, results in

hypercontractility of the basal part with almost no

contraction of the apical part. The mechanism of

this disease is yet unknown as of today. One of the

leading proposed mechanisms is the creation of

intraventricular gradients, due to geometrical

susceptibility. [Chockalingam et al, 2009], [Sharma

et al, 2011], [Holgar et al, 2010]

Methods

For understanding the mechanical behaviour of the

heart, including the basic properties of cardiac

muscles, a novel modelling approach is developed

along the following steps: a) a constitutive

mathematical model is constructed based on

mechanical experiments on myocardial tissue –

first, using a passive uni-axial device; following, a

passive bi-axial device; passive shear device; and

finally active upgrade for shear and biaxial devices.

b) patient-specific geometry and boundary

conditions are acquired, including the orientation

of the heart muscle fibers, from MRI data and

echocardiographic methods c) Combining all the

above into an organ-scale finite element (FE) model

using the commercial software ABAQUS.

Following the literature an orthotropic behaviour is

assumed; Constitutive laws and material properties

will be compared to the literature [Holzapfel et al,

2009], [Dokos et al, 2002], [Guccione et al,

1991,1993], [Wenk et al, 2011] and [Böl et al, in

press], and integrated into ABAQUS using a user-

subroutine (UMAT).

Results

Heart modelling concepts and preliminary results

from a uni-axial stretch experiment used to obtain

constants of constitutive model of a rat cardiac

muscle will be presented. The uni-axial experiment

shows general agreement with literature.

Figure 1: Uni-axial preliminary results

However, there is still a sizable gap, and therefore

bi-axial and shear passive, as well as active, devices

are constructed to fill it. Future plans will be

presented as well.

Discussion

The heart is basically an extremely durable pump

with many correction circles, but sometimes these

correction circles damage the heart, rather than

supporting it, thereby causing a decrease in cardiac

output and ultimately cardiac arrest and death.

Using the FE approach, further validation of the

proposed TC mechanism will be achieved.

Therefore, this work serves to demonstrate the

potential effectiveness of computational approach

in clinical treatment, facilitating adjustment of the

drug treatment to moderate or even negate the

natural correction circles that may cause damage,

and to allow a better healing rate. The advantage of

the computational approach is intensified greatly

investigating this disease, since clinicians still

struggle today with the ability to develop TC

artificially.

References

Böl et al, Int. J. Multiscale Comput. Eng., in press

Chockalingam et al, Crit. Care Med. 37:729-34,

2009

Guccione et al, J Biomech Eng 113:42–55, 1991

Guccione et al, J Biomech Eng. 115:82–90, 1993

Holger et al, Nat. Rev. Cardio. 7:187-193, 2010

Holzapfel et al, Phil. Trans. R. Soc. A 367, 3445–

3475, 2009

Wenk et al, J Biomech Eng. 133(4):044501, 2011

Sharma et al, Crit. Path. Cardio. 10:142-147, 2011

Presentation 1793 − Topic 13. Cardiovascular biomechanics S153

ESB2012: 18th Congress of the European Society of Biomechanics Journal of Biomechanics 45(S1)