Bartolucci-Passini-Severi model in tissue

Question

Hello everyone,

I was trying to use the BPS ventricular cell model in a 2D simulation of the “Basic tissue EP” example. 

The problem is that the model is particularly stiff, and with bench the simulation converges only for very small time steps (<2 us) or using cvode (max step of 0.3 ms). In either case a simple 2x2 cm tissue takes tens of minutes to solve 20 ms.

I also tried solving the 2 markovian models (for ICaL and IKr) separately with the markov_be method, but I didn’t get a benefit in the maximal step I could use for the integration with bench and so the simulations are still too slow... how can I fix this?

Here is the cellML of the model:

https://models.cellml.org/workspace/5fd/file/36c7253c0426d8fcd7326ec104e162b44b656174/BPS2020.cellml 

(with a mistake in Cao: the control value is 1.8 not 0.9), I'm also attaching how I imported it in EasyML:

https://opencarp.org/q2a/?qa=blob&qa_blobid=11054773068091813872

Thank you for the support,

Eugenio

Answer 1

Hi Eugenio,

Which ODEs are most stiff in your model? Some sodium gates?

One option could be to solve those with a higher order method, which could relax the requirements on the integration time step (a bit).

Do you have other options in mind? Otherwise, I think that one has to deal with the higher computational costs for more involved models.

Cheers,

Axel