Flow dynamics in the human carotid artery: I. Preliminary observations using a transparent elastic model.

PURPOSE: We developed an elastic, transparent, life-size model of the cranial vessels that allowed us to visualize carotid artery flows directly, and wish to report our observations and recorded data.
MATERIALS AND METHODS: The brachiocephalic arteries of 12 adult cadavers were cannulated and infused with acrylic. The heads were dissolved in alkali and, using a "lost wax" technique, a silicone model that reflected the shape and size of the original artery was produced. These models were connected to a closed circuit of flowing fluid. The fluid was rendered opaque by injecting isobaric dyes at various points in the streams.
RESULTS: These dye opacified slipstreams showed a relatively low flow area visible in the posterior and lateral aspect of the carotid bulb that acted as an internal buffer, and directed the more posterior lateral slipstreams anteriorly and at the same time increased their velocity. The cervical internal carotid artery was relatively straight and showed flow patterns that were essentially laminar. In the petrous internal carotid artery, the dye-opacified slipstreams began a helical flow pattern, and areas of flow reversal became apparent along the inner aspect (lesser curvature) of the bend. The central slipstreams tended to flow in a straighter line, passing close to, and sometimes striking the wall of, the outer portion (greater curvature) of the bend. In the cavernous internal carotid artery, helical flow continued. The central slipstreams struck the outer surface (greater curve) of the arterial bend. The point that the central slipstream struck the wall was more distal during systole than during diastole. At the supraclinoid section laminar flow again became established. Certain slipstreams selectively entered individual cranial branches.
CONCLUSION: The model we describe should allow more accurate study of complicated flow dynamics in vessels supplying the brain.