Page 159 - Advances in Biomechanics and Tissue Regeneration

8.4 WHOLE HEART CYCLE MODELING 155

1
FEM
PODI

0.1
Time (s)

0.01

0.001
Diastole IVC Ejection IVR
Cardiac phase
FIG. 8.11 Comparison of end-diastole, end-IVC, end-ejection, and end-IVR time spans generated from PODI against a conventional full-scale
simulation using FEM.

After the conventional full-scale simulation results are produced using EFG, the PODI calculation accuracy is now
investigated. On average, the error norms of the displacement, stress, and strain fields are 0.024, 0.032, and 0.022,
respectively. However, it is observed that those errors are not equally distributed across the different phases of a heart-
beat, as shown in Fig. 8.12. The highest error is recorded during the isovolumetric contraction phase. It is about 3.5–4
times higher than during the diastole filling phase. The computation errors of the ejection and isovolumetric relaxation
phases are either considerably lower or similar to that of the diastole filling phase. These error values show very little
variation as the energy conserved is varied from 70% to 100%. However, for the pressure-volume (PV) relationship of

0.04 0.04
Diastole Diastole
IVC IVC
0.035 Ejection 0.035 Ejection
IVR IVR
0.03 0.03
L 2 error 0.025 L 2 error 0.025

0.02 0.02
0.015 0.015

0.01 0.01

0.005 0.005
(A) (B)
0.09
Diastole
0.08 IVC
Ejection
IVR
0.07
L 2 error 0.06
0.05
0.04
0.03
0.02

(C) 0.01
FIG. 8.12 Solution field error across the diastole, isovolumetric contraction (ICV), ejection, and isovolumetric relaxation (IVR). (A) Displacement
field; (B) strain field; and (C) stress field.

I. BIOMECHANICS