[Clinical importance of assessment of collateral capacity in the circle of Willis. Benefit of a mathematical blood flow model for the every-day practice of vascular surgery].
Collateral capacity of the Willisian arteries is of clinical importance during and after carotid endarterectomies.


OBJECTIVE
Assessment of cerebral hemodynamics using a flow circulation model based on a mathematical formula.


METHODS
Four patients suffering from ischemic stroke in moribund stage were investigated using transcranial color-coded duplex sonography. By compressing the common carotid arteries, the function of the Willisian collaterals was assessed. After the death of the patients, the circles were removed, the diameters and lengths of the arterial segments were measured. The data were analysed with the mentioned circulation model.


RESULTS
The diameters of non-functioning collateral arteries were 0.4 mm, while that of the functional ones were 0.7 and 0.8 mm, respectively. In the two cases where the anterior communicating arteries did not function, a near-critical hemodynamical status was found in the end-arteries. This was especially true if the mean arterial blood pressure was 70 mmHg. The most critical hemodynamical status developed in case 4, where internal carotid occlusion on one side, a contralateral severe carotid stenosis and a non-functioning anterior communicating artery were observed.


CONCLUSIONS
A special flow circulation model based on mathematical formula enables the calculation of the cerebral blood flow in the different arterial segments of the circle of Willis. Further studies are needed to clarify whether the method can be used for preoperative modeling of the cross-clamping phase of carotid endarterectomy.
Orosz
L
L
Debreceni Egyetem Orvos- és Egészségtudományi Centrum Aneszteziológiai és Intenzív Terápiás Tanszék, 4012 Debrecen, Nagyerdei krt. 98.
Kanyári
Z
Z
Siró
P
P
Molnár
C
C
Uray
E
E
Fülesdi
B
B
D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D002941:Circle of Willis / Q000000981:diagnostic imaging / Q000502:physiology*; D003097:Collateral Circulation; D003661:Decision Support Techniques; D016894:Endarterectomy, Carotid / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D008432:Mathematical Computing; D008954:Models, Biological; D014463:Ultrasonography