Effects of Tissue Level Parameter Variation on Cardiac Output

1
Effects of Tissue Level Parameter Variation on
Cardiac Output

• By Randy Lee1
• Mentors Roy C.P. Kerckhoffs1 and David Abramson2
• Monash University, Clayton, Australia
• 20 August 2008

1 Department of Bioengineering, University of
California, San Diego, La Jolla, CA 92092 2
Faculty of Information Science, Monash
University, Clayton, Victoria, Australia
2
Anatomy and Physiology of the Heart

• Anatomy Blood Flow
• Right vs. Left Ventricle
• LV 3x mass, 2x thick
• The heart as a muscular pump
• Polarization in SA node
• Purkinje fibers
• Preload and afterload
• Contractility

1.

• Normal heart anatomy (cut section). Available at
  http//www.nlm.nih.gov/medlineplus/ency/imagepages
  /8672.htm. Accessed 18 August 2008.
• Katz, Arnold M. Physiology of the Heart, 4th ed.
  Philadelphia Lippincott Williams Williams.
  2001.

3
Motivation

• Systolic and Diastolic Heart Failure (HF)
• End stage in heart disease
• 2004 Cardiovascular diseases overall claimed
  861,826 lives (1 in 2.8) in the US.1
• HF was mentioned on 284,365 death certificates (1
  in 8).
• 57,120 (20) of which cited HF as the underlying
  cause
• Typical causes
• Systolic HF MI, dilated cardiomyopathies
• Diastolic HF Concentric ventricular hypertrophy
• Our question What is the role of contractility
  in heart failure?

1. Rosamond W, Flegal K, Furie K, et al. Heart
Disease and Stroke Statistics 2008 Update A
Report From the American Heart Association
Statistics Committee and Stroke Statistics
Subcommittee. Circulation. 2008117e25-e146.
4
Methods

• Finite element model of a dilated canine heart,
  coupled to pulmonic and systemic circulations1
• Continuity62
• Problem-solving environment for multi-scale
  modeling and data analysis, especially in
  bioengineering and physiology
• Two parameters
• Tension relationship between time to peak
  tension and sarcomere length time/µm
• Relaxation relationship between time to total
  relaxation and sarcomere length time/µm
• Nimrod/G3
• Powerful tool to sweep between 50 and 200 of
  normal physiological values, at finite steps
  (total of 110 jobs)
• Computing power derived from the PRAGMA grid

• Kerckhoffs et al. Coupling of a 3D Finite Element
  Model of Cardiac Ventricular Mechanics to Lumped
  Systems Models of the Systemic and Pulmonic
  Circulation.Ann Biomed Eng. 200735(1)1-18.
• Continuity Cardiac Mechanics Research Group.
  http//www.continuity.ucsd.edu/Continuity
• Nimrod Portal http//www.csse.monash.edu.au/davi
  da/nimrod/portal.htm

5
Results and Analysis

• Results Forthcoming!
• Some time consuming problems arose when coupling
  Continuity to computing clusters to allow
  parallelization
• Computations are currently running
• Analysis using MATLAB
• Each set of computations returns hemodynamic data
  (pressures, volumes, flows, etc.), as well as
  calculations of strains and stresses at each node
  of the FE model
• Specific measures (ejection fraction, dP/dt,
  stroke volume, etc.) can be used to compute
  cardiac output
• Determine how well the heart is working globally
  and regionally

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Acknowledgements

• Thanks to Drs. Roy Kerckhoffs and David Abramson
  for their mentorship and incredible help in
  making this project a success. Also to the
  members of Monash Universitys MESSAGE lab for
  their day to day guidance. Thanks especially to
  Blair Bethwaite, for his help configuring
  Continuity. And also to Fred Lionetti, CMRGs
  programmer and analyst, for sharing his expertise
  using Continuity.
• Finally, thank you to Dr. Peter Arzberger, Dr.
  Gabriele Weinhausen, and Teri Simas, without whom
  the PRIME program would not exist.

This project and much of the work upon which it
is based is supported by
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Thank You!

• Questions?