Systolic axial artery length reduction: an overlooked phenomenon in vivo

To demonstrate axial artery motion during the cardiac cycle, the common car otid arteries (CCA) of 10 pigs were exposed and equipped with piezoelectric crystals sutured onto the artery as axial position detectors. An echo-trac king system was used to simultaneously measure the CCA diameter. For each a nimal, data for pressure, length, and diameter were collected at a frequenc y of 457 Hz. At a mean pulse pressure of 33 +/- 8 mmHg, the mean systolodia stolic length difference was 0.3 +/- 0.01 mm for a mean arterial segment of 11.35 +/- 1.25 mm. Systolic and diastolic diameters were 4.1 +/- 0.3 and 3 .9 +/- 0.2 mm, respectively. The examined CCA segment displayed a mean axia l systolic shortening of 2.7%. This study clearly demonstrates, for the fir st time, that the length of a segment of the CCA changes during the cardiac cycle and that this movement is inversely correlated with pulse pressure. It is also apparent that the segmental axial strain is significantly smalle r than the diameter variation during the cardiac cycle and that the impact of the axial strain for compliance computation should be further evaluated.