We develop novel models for simulating pulse wave signals under a variety of physiological and patho-physiological conditions. These signals are produced by the pumping heart and its interaction with the blood and the distensible arterial walls (Alastruey et al. 2012)
Nektar1D is our in-house code for simulating blood pressure, blood flow, vessel area, and PPG pulse waves in a given network of compliant vessels subject to boundary and initial conditions. This is achieved by solving numerically the nonlinear, one-dimensional (1-D) equations of blood flow in compliant vessels. Nektar1D has been used in the clinically relevant studies described in here and to create populations of thousands of virtual subjects for in silico evaluation of pulse wave indices and algorithms.
We have developed methods for calibrating 1-D models and understanding physical mechanisms of the simulated pulse wave signals.
1-D modelling provides a good balance between accuracy and computational cost, as we have demonstrated by comparison against
(i) experimental data in a 1:1 scale cardiovascular simulator rig of the aorta and its larger branches made of silicone tubes (J Biomech, 2011 & 2007),
(ii) in vivo data in humans (J Royal Soc Interface, 2016) and rabbits (J. Biomech, 2009),
(iii) numerical data obtained by solving the full 3-D equations of blood flow in compliant vessels (J Royal Soc Interface, 2021 & 2016; Ann Biomed Eng, 2016; Int J Numer Meth Biomed Engng, 2015 & 2014).
We have also assessed the predictions of Nektar1D pulse waveforms compared to those produced by the 1-D codes of other groups in several benchmark test cases (Int J Numer Meth Biomed Engng, 2015). The input data for all benchmark cases, experimental data where available, and numerical solutions for each scheme, are available online, providing a comprehensive reference dataset to support the development of 1-D numerical models and schemes. The clinical data used for our in vivo verification in J Royal Soc Interface, 2016 can be downloaded from here.
These tests have shown the ability of the 1-D formulation to reproduce pulse waveforms in large systemic arteries under normal anatomical and physiological conditions and with the presence of stenoses and aneurysms (J Royal Soc Interface, 2021).