Thank you for replying! Here are the steps to reproduce the problem. If there is anything else I need to provide, please let me know.
My experiment is based on the 02_tissue/22_simple experiment. I downloaded a vtk cardiac from a recommended website by you and transferred it to a opencarp readable way(files containing .elem, .pts, etc.). Then I modified the `run.py` in 22_simple experiment with:
1. modify the meshname to this 3d cardiac model `meshname=name/of/my/cardiac/model`
2. choose two neighbor points in the cardiac model as the stimulus block, and use stim to define the box of stimulus.
stim = [
3. run `run.py`
Thanks again for your suggestions!