# Presentation: 657130

## 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](mailto:GuccioneJ@surgery.ucsf.edu)_
**National Biomedical Computation Resource (**_[http://](http://nbcr.net/)__[nbcr.net](http://nbcr.net/)__[/](http://nbcr.net/)_**)**
**NBCR Contact: **_[parzberg@ucsd.edu](mailto: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

## SAVER

## SAVER

## Pre-SAVER Model

## Post-SAVER Model

## Conclusion