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Zero-stress states of human pulmonary arteries and veins
1Department of Biomedical Engineering, The University of Memphis, Memphis, Tennessee 38152, USA.
Insights
Researchers studied the zero-stress states of human pulmonary arteries and veins. They found residual compressive stress in the inner vessel walls and tensile stress in the outer walls.
Area of Science:
- Cardiovascular physiology
- Biomechanical engineering
- Pulmonary medicine
Background:
- Pulmonary arteries and veins exhibit complex biomechanical properties.
- Understanding the zero-stress state is crucial for analyzing vascular mechanics.
Purpose of the Study:
- To determine the zero-stress states of human pulmonary arteries and veins.
- To quantify residual strains and estimate residual stresses in these vessels.
Main Methods:
- Vessels were dissected from human lungs within 15 hours postmortem.
- Rings were cut transversely and radially to measure opening angles.
- Residual strains were computed, and stresses estimated using Hooke's law.
Main Results:
- Mean opening angles ranged from 89 to 163 degrees in arterial and venous trees.
- Opening angles tended to increase with vessel size.
- Inner vessel walls experienced compression, outer walls experienced tension under zero-stress conditions.
Conclusions:
- Human pulmonary vasculature possesses intrinsic residual stresses.
- The inner walls are under greater compression than the outer walls are under tension.
Abstract:
The zero-stress states of the pulmonary arteries and veins from order 3 to order 9 were determined in six normal human lungs within 15 h postmortem. The zero-stress state of each vessel was obtained by cutting the vessel transversely into a series of short rings, then cutting each ring radially, which caused the ring to spring open into a sector. Each sector was characterized by its opening angle. The mean opening angle varied between 92 and 163 degrees in the arterial tree and between 89 and 128 degrees in the venous tree. There was a tendency for opening angles to increase as the sizes of the arteries and veins increased. We computed the residual strains based on the experimental measurements and estimated the residual stresses according to Hooke's law. We found that the inner wall of a vessel at the state in which the internal pressure, external pressure, and longitudinal stress are all zero was under compression and the outer wall was in tension, and that the magnitude of compressive stress was greater than the magnitude of tensile stress.