Local strain measurement of arterial wall based on longitudinal observation

The purpose of this study was to establish a method for measuring the circumferential difference in the deformation of artery walls during pressurization. Thoracic aortas of Japanese white rabbits were stretched to their in vivo length and pressurized to 80 mmHg in a physiological saline at room temperature. Four 5-mm long small needles (φ0.4 mm) were stuck perpendicularly into the aortic wall at equal intervals on a circumference. Displacement of the needles during pressurization from 0 to 200 mmHg was observed from longitudinal direction with a CCD camera and laterally with two cameras placed in an opposite direction across the aorta. The images of the cameras were used to identify the points at penetration of each needle and to obtain circumferential length between the needles. Circumferential stretch ratio was significantly higher in the ventral side than in the dorsal, indicating that mechanical heterogeneity exists even in healthy arteries. The present method may be useful for further understanding of vascular mechanics.