LAUSR

The angle of arterial tapering increases with aging, and the geometrical changes of the aorta may cause an increase in central arterial pressure and stiffness. The impact of tapering has been largely studied using frequency-domain transmission line theories. In this work, we revisit the problem of tapering and investigate its effect on blood pressure and pulse wave velocity (PWV) using a time-domain analysis with a one-dimensional computational model. First, tapering is modelled as a step-wise reduction in diameter and compared with results from a continuously tapered segment. Next, we studied wave reflections in a combination of step-wise diameter reduction of a straight vessels and bifurcations, then repeated the experiments with decreasing the length to physiological values. As the model' segments became shorter, wave reflections and re-reflections resulted in waves overlapping in time. We extended our work by examining the effect of increasing the tapering angle on blood pressure and wave intensity in physiological models: a model of the thoracic aorta and a model of upper thoracic and descending aorta connected to the iliac bifurcation. Vessels tapering inherently changed the ratio between the inlet and outlet cross-sectional areas, increasing the vessel resistance and reducing the compliance compared to non-tapered vessels. These variables influence peak and pulse pressure. In addition, it is well established that pulse wave velocity increases in an aging arterial tree. This work provides confirmation that tapering induces reflections and offers additional explanation to the observation of increased peak pressure and decreased diastolic pressure distally in the arterial tree. This article is protected by copyright. All rights reserved.