Key Points
- To evaluate in vivo wall shear stress measurements across different arterial locations and animal species, assessing the validity of classical vascular design models.
- Derived wall shear rates from in vivo velocity profiles recorded using custom ultrasound systems in large arteries and optical fluorescent tracer imaging in arterioles.
- Calculated wall shear stress using whole blood viscosity in conduit vessels and plasma viscosity in arterioles across humans and animal models.
- Mean wall shear stress in humans was substantially higher in the carotid artery (1.1–1.3 Pa) than in the brachial (0.4–0.5 Pa) and femoral arteries (0.3–0.5 Pa), while arteriolar values ranged from 1.0 to 5.0 Pa.
- Mean wall shear stress decreased linearly with body mass across species, declining in the infra-renal aorta from 8.8 Pa in mice to 0.5 Pa in humans.
- Vascular shear variations invalidate global application of Murray's cube law and square law, indicating theoretical power law exponents transition from roughly 2 near the heart to 3 in arterioles.
Structured PICO
PPopulationHumans and animals (various species including mice)
OOutcomeWall shear stress (WSS) in the arterial systemsurrogate
In vivo measurements demonstrate that wall shear stress varies significantly along the arterial tree and across species, challenging theoretical assumptions of constant WSS.