Presentation on theme: "MRI-Based Finite-Element Analysis of Left Ventricular Aneurysm Julius M. Guccione, Ph.D. Walker et al, Am J Physiol. 289:H692-700, 2005. UCSF/VAMC Cardiac."— Presentation transcript:
MRI-Based Finite-Element Analysis of Left Ventricular Aneurysm Julius M. Guccione, Ph.D. Walker et al, Am J Physiol. 289:H692-700, 2005. UCSF/VAMC Cardiac Biomechanics Laboratory San Francisco, California
Important Points Forces or stresses in the intact heart wall cannot be measured directly. Mathematical models for computing ventricular wall stress must be “validated” using regional 3-D strain measurements. Ventricular function (e.g., stroke volume versus end-diastolic pressure) is more important than ejection fraction and ventricular wall stress.
Prolate Spheroidal Coordinates Costa et al, J Biomech Eng. 1996 Nov;118(4):464-72
Contractile Dysfunction in Border Zone (BZ) Regions of LV Aneurysm
End-Systolic Circumferential Strain Comparison Walker et al, Am J Physiol. 289:H692-700, 2005. BA Figure 45
Effect of Active Cross-Fiber Stress Walker et al, Am J Physiol. 289:H692-700, 2005. Figure 56
Regional End-Systolic 3-D Stress Walker et al, Am J Physiol. 289:H692-700, 2005. Figure 67
Conclusions Active cross-fiber stress development is an integral part of LV systole; FE analysis with only uniaxial contraction is insufficient. Stress calculations from our validated models show 24% increase in fiber stress and 115% increase in cross-fiber stress at the BZ relative to remote regions.
Study Limitations No validation of estimated myocardial material properties using direct measurements (e.g., biaxial testing). In vivo boundary conditions are extremely complicated to model mathematically. A formal optimization of myocardial material parameters was not performed. Tagged MRI methodology was not state- of-the-art (e.g., C-SPAMM).
Virtual Tools for Cardiac Ventricular Remodeling Surgery
Necrosis-Specific MR Contrast Media in Rats Saeed et al, Circulation. 2001 Feb 13;103(6):871-6.