Deformations and end effects in isolated blood vessel testing.

Area of Science:

• Biomechanics
• Biomedical Engineering
• Cardiovascular Research

Background:

• Isolated blood vessel studies are vital for understanding mechanical and biological properties.
• Current methods using needle attachments to mimic in vivo conditions introduce complex, unquantified end effects.
• The boundaries of the homogeneous midsection region, essential for accurate measurements, remain underexplored.

Purpose of the Study:

• To define the extent of needle-induced end effects in isolated blood vessel experiments.
• To investigate how vessel geometry, material properties, loading conditions, and needle diameter influence these end effects.
• To establish criteria for identifying an uninfluenced midsection region for reliable data acquisition.

Main Methods:

• Utilized a computational fiber framework to model nonlinear anisotropic cylindrical tubes.
• Simulated vessel response under radial constraint at the ends, subjected to internal pressure and axial force.
• Employed a Fung-type strain energy function to define individual fiber constitutive response.

Main Results:

• Simulations showed axial stretch is highest near the needle constraint and decreases towards the midsection.
• Circumferential stretch exhibited an inverse relationship, increasing towards the midsection.
• The length of the disturbed region correlates with the difference between needle and vessel diameters under applied loads.

Conclusions:

• Quantified the influence of needle constraints on blood vessel deformation in isolated experimental setups.
• Provided a framework for understanding and defining the boundaries of the measurable midsection region.
• Findings are critical for improving the accuracy and interpretation of mechanical property measurements in vascular research.