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Arterial expansive remodeling induced by high flow rates
A Ben Driss1, J Benessiano, P Poitevin
1Unité 141 Institut National de la Santé et de la Recherche Médicale (INSERM), Hospital Lariboisière, Paris, France.
The American Journal of Physiology
|February 1, 1997
Summary
Chronic increase in aortic blood flow causes arterial wall remodeling. Increased shear stress promotes vasodilation, while elevated tensile stress leads to medial hypertrophy and fibrosis in the aortic wall.
Area of Science:
- Cardiovascular Physiology
- Vascular Biology
- Biomedical Engineering
Background:
- Arterial wall remodeling is a complex process influenced by hemodynamic forces.
- Understanding the specific roles of shear and tensile stress in this remodeling is crucial for cardiovascular health.
Purpose of the Study:
- To investigate the effects of chronic increased aortic blood flow on arterial wall remodeling in an in vivo rat model.
- To differentiate the roles of shear stress and tensile stress in aortic wall adaptation.
Main Methods:
- An aortocaval fistula (ACF) model was created in Wistar rats to induce chronic increases in aortic blood flow.
- Hemodynamic parameters (pressure, velocity, flow, shear stress) and aortic wall structure (cGMP content, medial cross-sectional area, elastin, collagen, smooth muscle cell hypertrophy) were measured upstream and downstream of the ACF immediately and 2 months after creation.
- Sham-operated rats served as controls.
Main Results:
- Upstream of the ACF, acute increases in blood velocity, flow, and shear stress were observed, along with elevated cGMP levels. After 2 months, sustained increases in aortic diameter and blood flow occurred, accompanied by medial hypertrophy, increased elastin and collagen content, and smooth muscle cell hypertrophy, despite decreased arterial wall thickness.
- Downstream of the ACF, acute pressure decrease was noted without significant changes in other hemodynamic parameters. After 2 months, decreased pressure, velocity, shear stress, and cGMP levels were observed, with only smooth muscle cell hypertrophy and hypoplasia noted in the aortic wall structure.
- Increased aortic wall tensile stress was consistently observed upstream.
Conclusions:
- Both shear stress and tensile stress play significant roles in aortic wall remodeling.
- Increased shear stress appears to drive expansive remodeling and flow-dependent vasodilation.
- Increased tensile stress is associated with medial hypertrophy and fibrosis, contributing to structural changes in the arterial wall.