INTRACAROTID PRESSURE MEASUREMENTS IN THE EVALUATION OF A COMPUTER-MODEL OF THE CEREBRAL-CIRCULATION

BACKGROUND It is difficult to predict which patients will tolerate occ lusion of the internal carotid artery. This difficulty arises primaril y because of uncertainties in the prediction of the adequacy of collat eral circulation. Because of these uncertainties, balloon test occlusi on and other methods have been developed to determine a priori the saf ety of carotid occlusion. However, all the methods are associated with significant false-positive and false-negative rates, as well as other neurologic complications. Because of these problems, more accurate an d less invasive methods for predicting tolerance of carotid occlusion are needed. METHODS In this report, we present the initial clinical ev aluation of a new method for assessing the collateral circulation aide d by a mathematical model of the cerebral vasculature. Data from the a ngiograms of 14 patients who underwent carotid endarterectomy were use d to create individualized simulations of their cerebral circulations. As a test of the accuracy of the simulations, we compared values of t he intracarotid stump pressures predicted by the model to those measur ed at surgery during the period of carotid occlusion. RESULTS The pres sure predictions of the model correlated well with those measured at s urgery. Linear regression analysis of measured versus predicted values yielded a line with slope 1.05. The line with slope 1.00, which denot es perfect agreement between predictions and measurements, is within t he 95% confidence interval of the slope determined from the regression analysis. CONCLUSIONS Mathematical models of the cerebrovascular circ ulation can provide good predictions of intravascular pressure in the collateral circulation, and may provide accurate predictions of the fl ow as well. The present study reveals several areas that need further development, such as the models of the microvasculature, measurement o f the arterial dimensions from angiograms, and consideration of other collateral sources such as the leptomeningeal and retrograde ophthalmi c sources of flow. Incorporation of these improvements may lead to a c linically useful, noninvasive assessment of the state of the cerebrova scular collateral circulation in the individual patient. (C) 1998 by E lsevier Science Inc.