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Extensibility changes of calcified soft tissue strips from human aorta
M H Sherebrin1, H A Bernans, M R Roach
1Department of Biophysics, University of Western Ontario, London, Canada.
Canadian Journal of Physiology and Pharmacology
|September 1, 1987
Summary
Aortic calcification, common in over half of examined aortas, weakens vessel strength. This study found calcified aortic tissue has lower breaking strength and strain, increasing risk for vascular disease.
Area of Science:
- Biomedical Engineering
- Cardiovascular Research
- Materials Science
Background:
- Aortic calcification is prevalent in over 50% of individuals across a wide age range.
- Calcification in the aorta occurs in patchy distributions.
- The mechanical implications of aortic calcification on vascular integrity are not fully understood.
Purpose of the Study:
- To investigate the influence of aortic calcification on the mechanical properties of aortic tissue.
- To determine the relationship between calcification and stress-strain behavior, breaking strength, and elasticity.
- To assess the significance of calcification in the context of vascular disease.
Main Methods:
- Autopsy examination of 59 aortas to identify calcification.
- Tensile testing of 5x30 mm aortic wall strips (calcified and uncalcified) using an Instron machine.
- Calculation of true stress, true strain, and slope from stress-strain curves at various points.
Main Results:
- Statistically significant differences were observed in 13 out of 36 measured categories between calcified and uncalcified aortic strips.
- Calcified aortic strips exhibited significantly lower breaking strength and strain compared to uncalcified strips.
- Mathematical transformation of stress-strain curves suggested that calcification immobilizes tissue, creating high-stress regions at boundaries.
Conclusions:
- Aortic calcification significantly alters the mechanical properties of the aortic wall, reducing its strength and elasticity.
- The observed mechanical changes associated with calcification may predispose the aorta to tissue breakdown and contribute to vascular disease.
- Calcification acts as a localized stiffening agent, potentially leading to stress concentration and failure at the calcified tissue-normal tissue interface.