• what is the problem?
  • deaths due to heart attacks per year
    • get figures from Brock's writeup
    • 1/3 of all deaths per year in US
  • Normal function
    • SA node sends out pulse, electricity propogates through heart
    • heart contracts in one unified motion.
  • heart attack - what is it?
    • Blood stops flowing, body dies without oxygen
    • heart falls out of rhythm. Show slide on normal vs. abnormal cardiac traces.
    • get pictures of normal heart beat versus abnormal heart beat
    • get pictures of normal propogation versus arrythmias
  • defibrillation
    • get picture of paddles - "I have a very nice high-res picture of these" --Brock
    • Idea: "reset the heart"
    • Override all activity with strong signal, let it decay naturally.
    • show movie of this if I'm able.
  • problems with defibrillation:
    • not as simple as it seems
      • requires extremely high voltage to be effective.
    • "Feels like getting kicked in the chest by a horse"
    • high voltage damages heart tissue.
• why do we want to study defirbillation on a computer?
  • mechanism for defibrillation still unknown problem
    • Some shocks work, others don't.
    • Changing the way you shock can greatly increase effectiveness.
  • Methods for gathering data in vitro
    • show picture of experimental set up
    • stick heart tissue full of pins, measure electric potential
    • optical mapping - inject chemicals that glow when heart contracts
  • problems
    • stick heart tissue full of pins, measure electric potential
      • invasive, changes the way electricity propogates
      • can only provide low spacial resolution
    • optical mapping - inject chemicals that glow when heart contracts
      • Can only get average of activity in first few layers, no internal information
    • hard to gather data in the field
    • expensive!
    • internals unknown!
  • Simulation
    • perfect data capture
      • Can view contraction, electrical properties, at every point in the interior of the heart
    • cheap
• bidomain equations - quick derivation
  • throughout these slides, show BD equations in corner
  • grey out things that we aren't talking about.
  • two cellulary spaces
  • picture of heart tissue at the cellular level
• Computational challenges.

-- RobBlake - 13 Nov 2006