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Virtual Tools for Cardiac Ventricular Remodeling Surgery Julius Guccione 1 , Mark Ratcliffe 1 and Andrew McCulloch 2 1 UCSF and 2 UCSD Contact for Research: Julius Guccione, GuccioneJ@surgery.ucsf.edu National Biomedical Computation Resource ( http://nbcr.net/ )
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Virtual Tools for Cardiac Ventricular Remodeling Surgery Julius Guccione1, Mark Ratcliffe1 and Andrew McCulloch2 1UCSF and 2UCSD Contact for Research: Julius Guccione, GuccioneJ@surgery.ucsf.edu National Biomedical Computation Resource (http://nbcr.net/) NBCR Contact: parzberg@ucsd.edu
How I Got Involved in the National Biomedical Computation Resource (NBCR) • Key Aim • Transparent access to the new and emerging grid infrastructure to conduct, catalyze and enable multiscale biomedical research • Key Technologies • Cluster and grid computing • Data and web services • Visualization and interfaces • Core Projects • Integrative Modeling of Subcellular Processes (J. Andrew McCammon, Kim Baldridge, Michael Holst, Nathan Baker, Philip Papadopoulos, Michel Sanner) • Data Integration and Analytic Tools for Molecular Sequences (Amarnath Gupta, Kim Baldridge, Mary Ann Martone) • Structurally and Functionally Integrated Modeling of Cell and Organ Biophysics (Andrew McCulloch, Anushka Michailova, Mark Ellisman, Michael Sanner, Philip Papadopoulos) • Creating Visualization Environments for Multi-Scale Biomedical Modeling (Michel Sanner, Aurthur Olson) • Grid Computing and Analysis for Multi-Scale Biomedical Applications (Peter Arzberger, Mark Ellisman, Kim Baldridge, Philip Papadopoulos, Michel Sanner, Wilfred Li)
How the NBCR Helped My Research • Realistic Mathematical (Finite Element) Modeling of the Beating Heart • Complex Geometry • Anisotropic Mechanical Properties • Large Deformation • Muscle Contraction • Continuity Website (www.continuity.ucsd.edu) • Software freely available on 3 platforms • 20 new releases in 2006 alone • Applications to Cardiac Surgery • 7 R01HL058759-03 (PI: Guccione, Julius M.) • 5 R01HL063348-08 (PI: Ratcliffe, Mark B.) • 5 R01HL077921-02 (PI: Guccione, Julius M.)
Applications to Cardiac Surgery: Example #1 • The global left ventricular dysfunction characteristic of left ventricular aneurysm is associated with muscle fiber stretching in the adjacent noninfarcted (border zone) region during isovolumic systole. • Three mathematical model simulations: • Normal border zone contractility and normal aneurysmal material properties => border zone muscle fiber shortening • Greatly reduced border zone contractility (by 50%) and normal aneurysmal material propertes => border zone muscle fiber stretching • Greatly reduced border zone contractility (by 50%) and stiffened aneurysmal material properties (by 1000%) => border zone muscle fiber stretching • The mechanism underlying mechanical dysfunction in the border zone region of left ventricular aneurysm is primarily the result of myocardial contractile dysfunction rather than increased wall stress in this region. Guccione et al, Ann Thorac Surg. 2001 Feb;71(2):654-62.
Applications to Cardiac Surgery: Example #2 • Infarcted segments of myocardium demonstrate functional impairment ranging in severity from hypokinesis to dyskinesis. • Mathematical model simulations: • Diastolic and systolic properties of the infarct necessary to produce akinesis were determined by assigning a range of diastolic stiffness and percentage of contracting myocytes. • As diastolic infarct stiffness was increased to 11 times normal, the percentage of contracting myocytes necessary for akinesis increased from 20% to 50%. • Without contracting myocytes, diastolic infarct stiffness 285 times normal was necessary to achieve akinesis. • Akinetic myocardial infarcts must contain contracting myocytes. Dang et al, Am J Physiol Heart Circ Physiol. 2005 Apr;288(4):H1844-50.
Applications to Cardiac Surgery: Example #3 • Surgical anterior ventricular restoration (SAVER) has been proposed for dilated ischemic cardiomyopathy with an akinetic distal anterior left ventricular (LV) wall. • Mathematical model simulations: • Separate versions of the model with normal and dilated LV sizes were developed and used to simulate the SAVER operation with and without a patch of varying stiffness. • In all cases, stroke volume decreased while ejection fraction increased after SAVER. • The SAVER operation was more beneficial in dilated ventricles, and the reduction in stroke volume after SAVER without patch was minimal. • These simulations support the use of SAVER in dilated hearts without a patch. Dang et al, Ann Thorac Surg. 2005 Jan;79(1):185-93.
SAVER Athanasuleas et al, J Am Coll Cardiol. 2001 Apr;37(5):1199-209.
SAVER Athanasuleas et al, J Am Coll Cardiol. 2001 Apr;37(5):1199-209.
SAVER Athanasuleas et al, J Am Coll Cardiol. 2001 Apr;37(5):1199-209.
Pre-SAVER Model Dang et al, Ann Thorac Surg. 2005 Jan;79(1):185-93.
Post-SAVER Model Dang et al, Ann Thorac Surg. 2005 Jan;79(1):185-93.
Conclusion Dang et al, Ann Thorac Surg. 2005 Jan;79(1):185-93.