Fenton-Karma model
Fenton-Karma model on a 1D ring:
Oscillations of APD
This applet simulates the propagation of action potentials on
a ring (the edge at the right is the same as the edge at the left).
An action potential is initiated by applying a stimulus. At short
ring lengths, the pacing cycle length is effectively decreased, and
alternans develop. The alternans are
spatially discordant; that is, as the wave propagates, it initiates
action potentials whose durations vary between long and short.
To use the applet, press the Start button.
This generates a single action potential that is initially blocked
on the right so it only propagates to the left.
The simulation can be paused with the Stop button
and resumed using the simulation and the
simulation will resume by using the Cont. button.
Click inside the plot to initiate more activations.
The location of each activation corresponds
to the location on the x-axis and the
magnitude of the activation corresponds to the
value on the y-axis.
To make the simulation run faster or slower,
click on the corresponding buttons. To return the membrane
potential of all cells to the rest value, click Reset.
To initiate the original single pulse, click Restart.
To adjust the size of the ring, click on Larger ring or Smaller ring.
Things to try:
Click Smaller ring to decrease the ring size and effectively decrease
the stimulation period. Decrease the size to around 225 points to see
alternans begin.
Decrease the ring size further to about 190 points to reach
conduction block, when the wave is extinguished.
Alternatively, increase the ring size before conduction block is
reached to determine the cycle length needed for alternans to be eliminated.
For more information, see
Fenton FH, Karma A. (1998) Phys Rev Lett 81, 481-484.