Simulation of arterial hemodynamics after partial prosthetic replacement of the aorta.

BACKGROUND: Replacing parts of the aorta with a non-compliant vascular prosthesis results in marked alterations of the aortic input impedance and influences arterial hemodynamics. We propose a mathematical model of circulation that can predict hemodynamic changes after simulation of vascular grafting.
METHODS: A new mathematical model of the human arterial system was developed on a 75-MHz Pentium personal computer using Matlab software. The human arterial tree was delineated according to a 128-branch design encompassing bifurcations and physical properties of the arterial wall. A digitized aortic flow wave was chosen as the input signal to the system. After determination of the modules of elasticity of native vascular tissue and standard prostheses in technical experiments, replacement of any part of the aorta with a prosthesis was simulated by increasing the elasticity in the parts desired.
RESULTS: During control conditions, the model displayed a physiologic distribution of flow and pressure waves throughout the arterial system. Simulated replacement of the aorta resulted in an increase in pressure amplitude and a partial loss of the aortic "Windkessel" function. Calculation of the aortic input impedance showed an increase in the characteristic impedance, whereas the peripheral resistance remained unaltered.
CONCLUSIONS: This mathematical model of the arterial circulation is useful for simulating hemodynamic changes after implantation of vascular grafts. The results of the model analysis are consistent with those in previous experimental work.