The common carotid artery provides significant pressure wave dampening in the young adult sheep

BACKGROUND:It has been established that the central elastic arteries of the mammalian circulation dampen the high pulse pressure emanating from the left ventricle, so that the pulsations in distal arterioles, such as in the cerebral circulation, are of lower amplitude than more centrally. However, the contribution of the common carotid artery (CCA) to protection of the cerebral microvasculature from high pulse pressure is not known, specifically to what extent viscoelastic energy dissipation in the arterial wall might contribute to the shock absorbing function of the large conduit arteries. METHODS:Young adult sheep (n = 6) were anaesthetised and their CCAs (n = 7) exposed. Pressure catheters were inserted 10-15 cm apart, proximally and distally in the CCA; a flow probe was placed proximally on the vessel. RESULTS:The median dp/dtmax on the pressure rise of the arterial wave upstroke for the proximal CCA was 619 mm Hg/s and for the distal CCA it was significantly lower, at 197 mm Hg/s (p = 0.0156; n = 7). The median pulse pressure of the proximal CCA was 24 mm Hg/s; distal pulse pressure was significantly lower, at 18 mm Hg/s (p = 0.0156; n = 7). The median flow rate was 0.97 L/min with an interquartile range from 0.51 to 1.15 L/min. CONCLUSIONS:The native CCA in the young adult sheep is an effective "pressure dampener" in the arterial circulation, reducing both pressure slope and pulse pressure, most likely via viscous dampening in the arterial wall.