This example demonstrates how to compute conduction velocity restitution in cardiac tissue. To run the experiments of this tutorial do
Conduction velocity restitution is an important property of cardiac tissue. As pacing frequency is increased, conduction velocity will become slower. For this tutorial, the user will shown how to construct conduction velocity restitution curves to describe the conduction properties of cardiac tissue in response to various pacing protocols.
A 1.0 cm cable of epicardial ventricular myocytes is used to generate a CV restitution curve for a user defined pacing protocol. The model domain was discretized with linear finite elements with an average edge length of 0.01 cm.
This tutorial uses the most recent version of the ten Tusscher ionic model for human ventricular myocytes [Tusscher2006] that was modified for the study [Bayer2016] . This ionic model is labeled GTT2_fast in openCARP's LIMPET library.
The left side of the 1D cable model is paced with 5-ms-long stimuli at twice capture amplitude for an S1S2 restitution pacing protocol defined by the user inputs.The user sets the cycle length and number of beats for S1 pacing, and the range of cycle lengths to apply for the S2.
Activation times are computed for each S2 beat of the pacing protocol using the openCARP option LATs (see tutorial X). CV is then computed along the cable by taking the difference in activation times at the locations 0.25 cm and 0.75 cm divided by the distance between the two points.
To run the experiments of this tutorial do
The following optional arguments are available (default values are indicated):
./run.py --help --Gil Default: 0.3650 S/m Intracellular longitudinal tissue conductivity --Gel Default: 1.3111 S/m Extracellular longitudinal tissue conductivity --nbeats Default: 5 Number of beats for S1 pacing at CI1 --CI0 Default: 300 ms Shortest S2 coupling interval --CI1 Default: 500 ms S1 cycle length and longest S2 coupling interval --CIinc Default: 25 ms Decrement for time interval from CI1 to CI0
After running run.py, the CI and CV are output into the ASCII file CVrestitution_GTT2_fast_bcl_.....
If the program is run with the
--visualize option, the CV restitution curve in the file above will be plotted using pythons plotting functions.
./run.py --CI0 300 --visualize --np 2
./run.py --CI0 275 --Gil 0.09125 --visualize --np 2
./run.py --CI0 275 --Gil 0.5475 --visualize --np 2
Bayer JD, Lalani GG, EJ Vigmond, SM Narayan, NA Trayanova. Mechanisms linking electrical alternans and clinical ventricular arrhythmia in human heart failure. Heart Rhythm, 13(9):1922-1931, 2016. [Pubmed]