Method of assessing the contribution of components of an anastomosing vascular network to total vascular impedance.

The cerebral circulation has extensive communications between its four feeder arteries, their tributaries, and the extracerebral arteries. A theoretically derived method and its experimental verification is described by which the various impedances in a network can be quantified. It involved serial observations of pulsatile pressure, flow, and input impedance, in response to a pattern of input vessel occlusions. Fourier analysis permitted the response of the network to be studied for the component frequencies, so that linear and phasor algebra could be used to obtain a solution. Possible errors introduced by assumptions in the original model are minimal, and do not invalidate the method in practice.