Relation of a Pulse Transit Time to the Blood Pressure in Bifurcated Cardiovascular Networks

Abstract

Recent developments in cardiovascular mathematics allow to simulate blood flow in the entire circulatory network or any isolated cardiovascular subsystem. Providing measurements of a Pulse Transit Time (PTT), or the averaged value for the Pulse Wave Velocity (PWV), the patient specific computational model can create personalized transfer functions, converting distal measurements to the set of cardiovascular biomarkers. The latter has a potential to build the feasible foundation for the personalized continuous self-monitoring of cardiovascular health based on portable mobile and wearable applications. Nevertheless, although being of a great interest, an accurate and reliable PTT-based Blood Pressure (BP) estimation barely exists nowadays due to the complexity of a BP regulation in a human body.In this paper we concentrate on a physics based computational modelling to assess interconnections of a PTT to BP in a bifurcated circulatory network. The PWV is interpreted as the speed of propagation along the forward running characteristic in a related hyperbolic Fluid Structure Interaction (FSI) differential problem. PTT is calculated by integrating the reciprocal of instantaneous PWV along the characteristic line. The Y.C. Fung's exponential model is applied to describe mechanics of a thin and a thick-walled vessel, subject to the infinitesimally small or finite hyperelastic deformation. Recently published PTT and PWV based non-invasive and continuous BP monitoring methods are reviewed and analyzed.