Comparison of pulse-wave velocity in different aortic regions in relation to the extent and severity of atherosclerosis between young and older Kurosawa and Kusanagi-Hypercholesterolemic (KHC) rabbits

The present study was performed to investigate the effects of the development of atherosclerosis on foot-to-foot pulse-wave velocity (PWV) from the ascending aorta to different positions along the aorta in Kurosawa and Kusanagi-Hypercholesterolemic (KHC) rabbits aged 10–12 and 22–24 months old, in relation to the percentage fractional lesioned area (PFLA) in different aortic regions through which the pulse wave travels, as well as the rheological and pathohistological properties of the aortic wall. PWV, when measured in the KHC rabbit from the ascending aorta to each aortic position, showed the highest value on passage through the aortic arch, decreased with conduction to the distal thoracic aorta, reached the minimal value on passage to the distal thoracic aorta or to the middle abdominal aorta in the 10–12- and 22–24-month-old animals respectively, and increased gradually on conduction to the iliac artery. PWV at all aortic regions examined was significantly greater in the 22–24-month-old than in the 10–12-month-old KHC rabbits. PFLA, when measured in the aortic region from the ascending aorta to each aortic position, was maximal in the aortic arch and decreased gradually towards the peripheral aorta in both age groups. PFLA in the 22–24-month-old group was significantly greater than that in the 10–12-month-old group in all aortic regions examined. The atherosclerotic aortic wall showed a significantly lower elastic modulus in the young KHC rabbits compared with age-matched normal rabbits. A significantly higher elastic modulus was observed in the older KHC rabbits compared with that in the younger animals of both strains, associated with the progression of sclerosis. These findings indicate that the increase in PWV is due mainly to an increase with aging in the extent and severity of atherosclerosis in vessels in which the pulse wave travels.