P.091 A Patient Specific Wave Propagation Model of the Upper Limb

Abstract

In this study, a patient specific lumped parameter model is used to investigate pressure wave propagation phenomena and estimate mechanical properties of large arteries of the upper limb.

A set of local ultrasound measurements was obtained from a group of 7 healthy volunteers to provide vessel wall distension (WD) and blood velocity at several positions. Blood volume flow (BVF) is estimated from the centerline velocity using the Womersley profile method. The lumped parameters R, L, C along the arm are computed with a linear interpolation method from local blood pressure (BP) and WD. Thus, an entire arterial tree model, from the arm pit to the wrist, modeling the brachial, radial and ulnar arteries, is built. Time average BVF and BP values are used to determine the end impedance of the extremities. The BVF at the more proximal site is used as input for the simulations.

Simulated BVF and BP curves are compared with the in-vivo results. A reverse method adapts the model parameters resulting in values reflecting physiological results.

The results show that the shape of the simulated BVF along the arm is comparable with the in-vivo estimations. However, large differences are observed between simulated BP and in-vivo assessed WD curves. We hypothesize that those differences are due to the non-linear and viscoelastic properties of the arterial wall. Therefore, a continuous wave propagation model which takes those properties into account should be implemented. The experimental simulations provide and suggest improved physiological modeling of the pressure/flow relationships.