Virtual Tools for Cardiac Ventricular Remodeling Surgery

1
Virtual Tools for Cardiac Ventricular Remodeling
Surgery

• Julius Guccione1, Mark Ratcliffe1 and Andrew
  McCulloch2
• 1UCSF and 2UCSD
• Contact for Research Julius Guccione,
  GuccioneJ_at_surgery.ucsf.edu
• National Biomedical Computation Resource
  (http//nbcr.net/)
• NBCR Contact parzberg_at_ucsd.edu

2
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)

3
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.)

4
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 gt border zone
  muscle fiber shortening
• Greatly reduced border zone contractility (by
  50) and normal aneurysmal material propertes gt
  border zone muscle fiber stretching
• Greatly reduced border zone contractility (by
  50) and stiffened aneurysmal material properties
  (by 1000) gt 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
Feb71(2)654-62.
5
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
Apr288(4)H1844-50.
6
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
Jan79(1)185-93.
7
SAVER
Athanasuleas et al, J Am Coll Cardiol. 2001
Apr37(5)1199-209.
8
SAVER
Athanasuleas et al, J Am Coll Cardiol. 2001
Apr37(5)1199-209.
9
SAVER
Athanasuleas et al, J Am Coll Cardiol. 2001
Apr37(5)1199-209.
10
Pre-SAVER Model
Dang et al, Ann Thorac Surg. 2005
Jan79(1)185-93.
11
Post-SAVER Model
Dang et al, Ann Thorac Surg. 2005
Jan79(1)185-93.
12
Conclusion
Dang et al, Ann Thorac Surg. 2005
Jan79(1)185-93.