Wave reflection associates with cardiovascular events. However, it is less clear what information on arterial function, such as arterial stiffness and vascular resistance, can be derived. We therefore set out to find the relations between parameters obtained from wave shape analysis (Augmentation Index, Inflection and Shoulder points) and from wave separation analysis (Reflection Magnitude, and arrival time of the reflected wave) and aortic stiffness and taper.

Methods. We used a distributed model of the systemic arterial tree with properties as reported in earlier studies^1,2. We changed vascular resistance, arterial stiffness and aortic taper.

Results. Peripheral Resistance has a negligible effect on wave reflection. Backward wave amplitude results, by equal amounts, from the distal aortic reflection (at length L) and from geometric taper and (other) aortic side branches. The wave reflected at the distal aorta runs with the same Pulse Wave Velocity (PWV) as the forward wave. The return time of the reflected wave, t_return, varies a factor two between small and strong taper. The t_return decreases 20% between aortic PWV’s of 6 and 12 m/s, while 50% is predicted from 2L/t_return. The timing of the shoulder and inflection points change with aortic stiffness but also less than predicted from 2L/PWV. The Augmentation Index and Reflection Magnitude (P_backward/P_forward) depend nonlinearly on stiffness; they increase with stiffness for low stiffness but not at high stiffness.

Characteristic impedance is needed for wave separation and therefore gives no independent information.

Conclusion. The data derived from wave form analysis and wave separation give poor information on arterial stiffness, no information on resistance and cannot be used to estimate these arterial parameters.