Figure 1.

Overview of model workflow for fitting afterload model (upper panel) and combined EM LV model (lower panel). In a first step, the Wk3 afterload parameters Z, Z_v, R and C were identified using measured haemodynamic parameters p_op, m, ${\hat{p}}_{\text{m}}$, p_cl, m, Δp_av, m and q(t) = −dV/dt as inputs. For AS cases, p_op, m and ${\hat{p}}_{\text{m}}$ were estimated from cuff measurements, whereas p_cl, m was estimated from empirical reference data. Subsequently, the EM LV model is fitted. First, the biomechanical bulk modulus C_Guc is adjusted to fit the passive behaviour of the LV model to the empirical approximation of the end-diastolic pressure–volume relation (EDPVR) due to Klotz, using {V_ed, p_lv, ed} as inputs. For AS cases p_lv, ed was estimated from empirical reference data. Using the fitted afterload model coupled to the EM LV model through a resistive valve model, the active stress model is parametrized using fixed-point iterations to adjust the phenomenological active stress model parameters, $\{{\tau }_{\text{C}},{\hat{S}}_{\text{a}},T_{\text{dur}},{\tau }_{\text{R}}\}$, using the discrepancy between measured and simulated $p-V$ metrics during isovolumetric contraction and ejection. In the diagram: EF, ejection fraction; ESV, end-systolic volume; and EDV, end-diastolic volume. (Online version in colour.)