CepModTtp.h

// SPDX-FileCopyrightText: Copyright (c) Stanford University, The Regents of the University of California, and others.
// SPDX-License-Identifier: BSD-3-Clause
 
#ifndef CEP_MOD_TTP_H 
#define CEP_MOD_TTP_H 
 
#include "Array.h"
#include "Vector.h"
#include <array>
 
#include <optional>
#include <functional>
 
template <class T>
T& make_ref(T&& x) { return x; }
 
/// @brief This module defines data structures for ten Tusscher-Panfilov
/// epicardial cellular activation model for cardiac electrophysiology
///
/// The classes defined here duplicate the data structures in the Fortran TPPMOD module defined 
/// in CEPMOD_TTP.f and PARAMS_TPP.f files. 
class CepModTtp
{
  public:
    CepModTtp();
    ~CepModTtp();
 
 
//--------------------------------------------------------------------
//
//     Constants for TenTusscher-Panfilov Ventricular Myocyte Model.
//
//--------------------------------------------------------------------
 
//     Default model parameters
      /// Gas constant [J/mol/K]
      double Rc = 8314.472;
 
      /// Temperature [K]
      double Tc = 310.0;
 
      /// Faraday constant [C/mmol]
      double Fc = 96485.3415;
 
      /// Cell capacitance per unit surface area [uF/cm^{2}]
      double Cm = 0.185;
 
      /// Surface to volume ratio [um^{-1}]
      double sV = 0.2;
 
      /// Cellular resistivity [\f$\Omega\f$-cm]
      double rho = 162.0;
 
      /// Cytoplasmic volume [um^{3}]
      double V_c = 16.404E-3;
 
      /// Sacroplasmic reticulum volume [um^{3}]
      double V_sr = 1.094E-3;
 
      /// Subspace volume [um^{3}]
      double V_ss = 5.468E-5;
 
      /// Extracellular K concentration [mM]
      double K_o = 5.4;
 
      /// Extracellular Na concentration [mM]
      double Na_o = 140.0;
 
      /// Extracellular Ca concentration [mM]
      double Ca_o = 2.0;
 
      /// Maximal I_Na conductance [nS/pF]
      double G_Na = 14.838;
 
      /// Maximal I_K1 conductance [nS/pF]
      double G_K1 = 5.405;
 
      /// Maximal epicardial I_to conductance [nS/pF]
      Vector<double> G_to = {0.294, 0.073, 0.294};
 
      /// Maximal I_Kr conductance [nS/pF]
      double G_Kr = 0.153;
 
//     G_Kr for spiral wave breakup
//      double G_Kr = 0.172;     // units: nS/pF
 
      /// Maximal epicardial I_Ks conductance [nS/pF]
      Vector<double> G_Ks = {0.392, 0.392, 0.098};
 
//     G_Ks for spiral wave breakup (epi)
//      double G_Ks(3) = (/0.441, 0.392_RKIND, 0.098_RKIND/)
 
      /// Relative I_Ks permeability to Na [-]
      double p_KNa = 3.E-2;
 
      /// Maximal I_CaL conductance [cm^{3}/uF/ms]
      double G_CaL = 3.98E-5;
 
      /// Maximal I_NaCa [pA/pF]
      double K_NaCa = 1000.;
 
      /// Voltage dependent parameter of I_NaCa [-]
      double gamma = 0.35;
 
      /// Ca_i half-saturation constant for I_NaCa [mM]
      double K_mCa = 1.38;
 
      /// Na_i half-saturation constant for I_NaCa [mM]
      double K_mNai = 87.5;
 
      /// Saturation factor for I_NaCa [-]
      double K_sat = 0.1;
 
      /// Factor enhancing outward nature of I_NaCa [-]
      double alpha = 2.5;
 
      /// Maximal I_NaK [pA/pF]
      double p_NaK = 2.724;
 
      /// K_o half-saturation constant of I_NaK [mM]
      double K_mK = 1.;
 
      /// Na_i half-saturation constant of I_NaK [mM]
      double K_mNa = 40.;
 
      /// Maximal I_pK conductance [nS/pF]
      double G_pK = 1.46E-2;
 
//     G_pK for spiral wave breakup
//      double G_pK = 2.19E-3;    // units: nS/pF
 
      /// Maximal I_pCa conductance [pA/pF]
      double G_pCa = 0.1238;
 
//     G_pCa for spiral wave breakup
//      double G_pCa = 0.8666;    // units: pA/pF
 
      /// Half-saturation constant of I_pCa [mM]
      double K_pCa = 5.E-4;
 
      /// Maximal I_bNa conductance [nS/pF]
      double G_bNa = 2.9E-4;
 
      /// Maximal I_bCa conductance [nS/pF]
      double G_bCa = 5.92E-4;
 
      /// Maximal I_up conductance [mM/ms]
      double Vmax_up = 6.375E-3;
 
      /// Half-saturation constant of I_up [mM]
      double K_up = 2.5E-4;
 
      /// Maximal I_rel conductance [mM/ms]
      double V_rel = 0.102;
 
      /// R to O and RI to I, I_rel transition rate [mM^{-2}/ms]
      double k1p = 0.15;
 
      /// O to I and R to RI, I_rel transition rate [mM^{-1}/ms]
      double k2p = 4.5E-2;
 
      /// O to R and I to RI, I_rel transition rate [ms^{-1}]
      double k3 = 6.E-2;
 
      /// I to O and Ri to I, I_rel transition rate [ms^{-1}]
      double k4 = 5.E-3;
 
      /// Ca_sr half-saturation constant of k_casr [mM]
      double EC = 1.5;
 
      /// Maximum value of k_casr [-]
      double max_sr = 2.5;
 
      /// Minimum value of k_casr [-]
      double min_sr = 1.;
 
      /// Maximal I_leak conductance [mM/ms]
      double V_leak = 3.6E-4;
 
      /// Maximal I_xfer conductance [mM/ms]
      double V_xfer = 3.8E-3;
 
      /// Total cytoplasmic buffer concentration [mM]
      double Buf_c = 0.2;
 
      /// Ca_i half-saturation constant for cytplasmic buffer [mM]
      double K_bufc = 1.E-3;
 
      /// Total sacroplasmic buffer concentration [mM]
      double Buf_sr = 10.;
 
      /// Ca_sr half-saturation constant for subspace buffer [mM]
      double K_bufsr = 0.3;
 
      /// Total subspace buffer concentration [mM]
      double Buf_ss = 0.4;
 
      /// Ca_ss half-saturation constant for subspace buffer [mM]
      double K_bufss = 2.5E-4;
 
      /// Resting potential [mV]
      double Vrest = -85.23;
 
//     Electromechanics coupling parameters: active stress model
      /// Resting Ca concentration [mM]
      double Ca_rest = 5.E-5;
 
      /// Critical Ca concentration [mM]
      double Ca_crit = 8.E-4;
 
      /// Saturation of concentration [MPa/mM]
      double eta_T = 12.5;
 
      /// Minimum activation [ms^{-1}]
      double eps_0 = 0.1;
 
      /// Maximum activation [ms^{-1}]
      double eps_i = 1. ;
 
      /// Transition rate [mM^{-1}]
      double xi_T = 4.E3;
 
//     Electromechanics coupling parameters: active strain model
//
 
      /// Active force of sacromere [-mM^{-2}]
      double alFa = -4.E6;
 
      /// Resting Ca concentration [mM]
      double c_Ca0 = 2.155E-4;
 
      /// Viscous-type constant [ms-mM^{-2}]
      double mu_Ca = 5.E6;
 
//     Force-length relationship parameters
      /// Initial length of sacromeres [um]
      double SL0 = 1.95;
 
      /// Min. length of sacromeres [um]
      double SLmin = 1.7;
 
      /// Max. length of sacromeres [um]
      double SLmax = 2.6;
 
      /// Fourier coefficients
      double f0  = -4333.618335582119;
      double fc1 =  2570.395355352195;
      double fs1 = -2051.827278991976;
      double fc2 =  1329.53611689133;
      double fs2 =  302.216784558222;
      double fc3 =  104.943770305116;
      double fs3 =  218.375174229422;
 
//-----------------------------------------------------------------------
//     Scaling factors
      /// Voltage scaling
      double Vscale  = 1.;
 
      /// Time scaling
      double Tscale  = 1.;
 
      /// Voltage offset parameter
      double Voffset = 0.;
 
//-----------------------------------------------------------------------
//     Variables
      /// Reverse potentials for Na, K, Ca
      double E_Na;
      double E_K;
      double E_Ca;
      double E_Ks;
//     Cellular transmembrane currents
      /// Fast sodium current
      double I_Na;
 
      /// inward rectifier outward current
      double I_K1;
 
      /// transient outward current
      double I_to;
 
      /// rapid delayed rectifier current
      double I_Kr;
 
      /// slow delayed rectifier current
      double I_Ks;
 
      /// L-type Ca current
      double I_CaL;
 
      /// Na-Ca exchanger current
      double I_NaCa;
 
      /// Na-K pump current
      double I_NaK;
 
      /// plateau Ca current
      double I_pCa;
 
      /// plateau K current
      double I_pK;
 
      /// background Ca current
      double I_bCa;
 
      /// background Na current
      double I_bNa;
 
      /// sacroplasmic reticulum Ca leak current
      double I_leak;
 
      /// sacroplasmic reticulum Ca pump current
      double I_up;
 
      /// Ca induced Ca release current
      double I_rel;
 
      /// diffusive Ca current
      double I_xfer;
//-----------------------------------------------------------------------
//     State variables
      double V;
      double K_i;
      double Na_i;
      double Ca_i;
      double Ca_ss;
      double Ca_sr;
      double R_bar;
 
//     Gating variables (runtime, steady state)
      double xr1, xr1i;
      double xr2, xr2i;
      double xs, xsi;
      double m, mi;
      double h, hi;
      double j, ji;
      double d, di;
      double f, fi;
      double f2, f2i;
      double fcass, fcassi;
      double s, si;
      double r, ri;
 
//     Other variables
      double k1;
      double k2;
      double k_casr;
      double O;
 
//     Jacobian variables
      double E_Na_Nai, E_K_Ki, E_Ca_Cai, E_Ks_Ki, E_Ks_Nai;
      double I_Na_V, I_Na_Nai;
      double I_to_V, I_to_Ki;
      double I_K1_V, I_K1_Ki;
      double I_Kr_V, I_Kr_Ki;
      double I_Ks_V, I_Ks_Ki, I_Ks_Nai;
      double I_CaL_V, I_CaL_Cass;
      double I_NaCa_V, I_NaCa_Nai, I_NaCa_Cai;
      double I_NaK_V, I_NaK_Nai;
      double I_pCa_Cai;
      double I_pK_V, I_pK_Ki;
      double I_bCa_V, I_bCa_Cai;
      double I_bNa_V, I_bNa_Nai;
      double I_leak_Cai, I_leak_Casr;
      double I_up_Cai;
      double I_rel_Cass, I_rel_Casr, I_rel_Rbar;
      double I_xfer_Cai, I_xfer_Cass;
      double k_casr_sr, k1_casr, O_Casr, O_Cass, O_Rbar;
 
    void actv_strn(const double c_Ca, const double I4f, const double dt, double& gf);
    void actv_strs(const double c_Ca, const double dt, double& Tact, double& epsX);
 
    void getf(const int i, const int nX, const int nG, const Vector<double>& X, const Vector<double>& Xg, 
        Vector<double>& dX, const double I_stim, const double K_sac, Vector<double>& RPAR);
 
    void getj(const int i, const int nX, const int nG, const Vector<double>& X, const Vector<double>& Xg, 
        Array<double>& JAC, const double Ksac);
 
    void init(const int imyo, const int nX, const int nG, Vector<double>& X, Vector<double>& Xg);
 
    void init(const int imyo, const int nX, const int nG, Vector<double>& X, Vector<double>& Xg,
        Vector<double>& X0, Vector<double>& Xg0);
 
    void integ_cn2(const int imyo, const int nX, const int nG, Vector<double>& X, Vector<double>& Xg,
        const double Ts, const double dt, const double Istim, const double Ksac, 
        Vector<int>& IPAR, Vector<double>& RPAR);
 
    void integ_fe(const int imyo, const int nX, const int nG, Vector<double>& X, Vector<double>& Xg, 
        const double Ts, const double dt, const double Istim, const double Ksac, Vector<double>& RPAR);
 
    void integ_rk(const int imyo, const int nX, const int nG, Vector<double>& X, Vector<double>& Xg, 
        const double Ts, const double dt, const double Istim, const double Ksac, Vector<double>& RPAR);
 
    void update_g(const int i, const double dt, const int n, const int nG, const Vector<double>& X, 
        Vector<double>& Xg);
 
};
 
#endif