To what extent does aortic pulse wave velocity estimate early atherosclerosis in Kurosawa and Kusanagi-hypercholesterolemic rabbits?

Pulse wave velocity (PWV), an index of arterial stiffness, is dependent not only on structural alterations in arterial wall but also on distending pressure, which could be related to wall distensibility. We investigated the efficacy of aortic PWV (AoPWV) for detecting early to moderate atherosclerosis in Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits. Pressure waves were recorded at the ascending, and proximal and distal abdominal aortas in 13 male normal and KHC rabbits aged 12 months under pentobarbital anesthesia when angiotensin II or sodium nitroprusside was infused intravenously. AoPWV was compared between the two rabbit groups at different mean arterial pressure (MAP) levels. Vascular diameter (D(m)) was measured using an intravascular ultrasound imaging system in the proximal thoracic and proximal abdominal aortas to determine pressure-strain elastic modulus (E(p)). AoPWV was correlated to MAP in the two rabbit groups (P < 0.001). AoPWV was slightly but significantly greater (< 0.5 m s(-1)) in the KHC rabbit group than in the normal rabbit group at MAP level >80 mm Hg (P < 0.01). The value of h/D(m) (h, wall thickness) was significantly high in the KHC rabbit group at any MAP level (P < 0.001) in these aortic regions. There was no significant difference in E(p) and D(m) between the two rabbit groups at any MAP level. AoPWV showed only a slight but significant increase in the young KHC rabbits at different MAP levels, which was mainly due to the increased h/D(m). AoPWV could underestimate aortic stiffness due to early to moderate atherosclerosis if AoPWV was adjusted for arterial pressure level.