Background

• I received my doctoral degree in Bioengineering jointly from the University of California, Berkeley and the University of California, San Francisco.  My thesis work was performed under Professor Kevin Healy of Berkeley, and focused on cardiac tissue engineering.  I also worked extensively with Professor Julius Guccione of UCSF during this time developing mathematical models of the left ventricle to test hypotheses related to tissue engineering applications. 

Work at Simula

• My goal as a post doctoral researcher at the Center for Biomedical Computing is to use and develop emerging computational platforms to translate experimental cardiac inquiries into the realm of computer science.  With input from clinicians and researchers, the use of advanced mathematical representations of the heart, as well as new methods and techniques for rapidly and efficiently solving these complex numerical systems, creates a powerful set of tools for theoretically examining the function and dysfunction of cardiac tissue.

Research Interests

Computational cardiac electromechanics and mechano-electric feedback (MEF) in cardiac tissue.

• MEF may play a very important role in generating electrical dispersion of activation and action potentials in the beating heart and ultimately in the formation of arrhythmias.  Developing and solving mathematical models that incorporate the entire cycle of excitation and contraction as well as the interactions between them and changing boundary conditions may help researchers understand how certain tissue states may provide a substrate for dangerous cardiac events or offer clues to treatment options.

• The ability to probe biological questions improves with the development of new, more physiologically accurate representations of the heart.  It is now possible to create accurate simulations of the injured heart to understand how the pathology of an infarct may alter both electrophysiology and stress fields in the ventricle through the complete cardiac cycle; where such injuries can serve as a driver for continued remodeling and ultimately heart failure.        

• Via improved mathematical systems to theoretically determine functional aspects of the heart, the ability to evaluate treatment options in silico presents a powerful means to test hypotheses or optimize effects prior to moving to expensive in vivo or clinical trials.  Surgical, medical, and regenerative medicine treatments are all potentially amenable to this approach, and we plan to target cardiac resynchronization therapy (CRT), and tissue engineering methods in our future research.

RECENT WORK:

• Osnes H, Thorvaldsen T, Wall ST, Sundnes J, McCulloch AD.  “An Operator Splitting Technique for Integrating Cardiac Electro-Mechanics.”  Submitted for publication
• Wall ST, Wenk JF, Peterson RC, Helgerson SL, Sabbah HN, Burger M, Stander N, Ratcliffe MB, Guccione JM.  “Implantation of Polymeric Material into the Globally Failing Left Ventricle Reduces Pathologic Myofiber Stress – A Finite Element Model Simulation.”  Submitted for publication
• Wall ST, Yeh C, Tu RYK, Mann MJ, Healy KE. “Biomimetic Extracellular Matrices for Stem Cell Transplantation and Myocardial Stabilization.”  Accepted for publication.  Journal of Biomedical Materials Research, Part A
• Su J, Wall ST, Healy KE, Wildsoet CF,  “Scleral Reinforcement Through Host Tissue Integration with Biomimetic Enzymatically Degradable Semi-Interpenetrating Polymer Network “ Tissue Engineering Part A, 2010 16(3)   
• Jhun, CS, Wenk, JF, Zhang, ZH, Wall ST, Sun K, Sabbah HN, Ratcliffe MB, Guccione JM. Effect of Adjustable Passive Constraint on the Failing Left Ventricle: A Finite-Element Model Study.” Annals of Thoracic Surgery, 2010 89(1)
• Wenk JF, Wall ST, Peterson RC, Helgerson SL, Sabbah HN, Burger M, Stander N, Ratcliffe MB, Guccione JM.  “A Method for Automatically Optimizing Medical Devices for Treating Heart Failure:  Designing Polymeric Injection Patterns.”  Journal of Biomedical Engineering. 2009 Dec 131(12)
• Wall ST, Saha KS, Schaffer DV, Healy KE. “Multivalency of Sonic Hedgehog Conjugated to Linear Polymer Chains Modulates Protein Potency.”  Bioconjugate Chemistry, 2008, April:19(4):806-812
• Ho JE, Chung EH, Wall ST, Schaffer, DV, Healy KE.  “Immobilized Sonic Hedgehog N-terminal Signaling Domain Enhances Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells.” Journal of Material Research Part A. 2007 Jun 28.
• Wall ST, Walker JC, Healy KE, Ratcliffe MB, Guccione JM.  “Theoretical Impact of the Injection of Material into the Myocardium: a Finite Element Model Simulation.” Circulation. 2006 Dec 12;114(24):2627-35.

PRESENTATIONS

• Center for Heart Failure Research 7^th Annual Symposium.  Oslo, Norway, 2009 -  “Electromechanical Modeling of the Infarct Injured Failing Ovine Heart”
• European Society of Cardiology, Heart Failure Congress. Nice, France, 2009  - “Implantation of Polymeric Material into the Globally Failing Left Ventricle Reduces Pathologic Myofiber Stress – A Finite Element Model Simulation.”
• Simula Symposium. Oslo, Norway, 2009 - “Computer Modeling of Cardiac Electro-Mechanics, Applications to Acute Myocardial Infarctions and Heart Failure”
• Society for Biomaterials, Chicago, IL, 2007. - “Multivalent Sonic Hedgehog as an Enhanced Potency Biomaterial Modification”
• Keystone Symposium. Santa Fe, NM, 2006 - “Changes in Cardiac Mechanics through Addition of Material to the Myocardium: A Finite Element Study”

BOOK CHAPTER

“Left Ventricular Implantation of Biomaterials”  Samuel Wall, Jonathan Wenk, Choon-Sik Jhun, Julius Guccione.  In: Computational Cardiovascular Mechanics - Modeling and Applications in Heart Failure.  Edited by:  Julius M. Guccione, Ghassan S. Kassab and Mark B. Ratcliffe, Chapter 14, pp 227 -239. Springer.