Pressure-Pressure Loop: A Novel Method for Biophysical Characterization of Blood Vessels.

Abstract

Purpose: To develop and evaluate a pressure-only method for localized functional characterization of synthetic vascular models and vascular grafts by capturing their integrated dynamic response and its interaction with stenosis severity.

Methods: An in-vitro closed-loop pulsatile flow system tested seven vascular models and grafts (silicone, latex, ePTFE, Dacron) at 0, 50, and 90% lumen narrowing. Two proximal high-fidelity pressure sensors recorded intraluminal pressure waveforms to construct pressure-pressure loops. Loop behavior was evaluated qualitatively through loop morphology and quantitatively using the slope descriptor (α). Uniaxial tensile testing provided independent Young's modulus measurements.

Results: Increasing stenosis altered pressure magnitude while characteristic loop patterns remained recognizable across conditions, with severe stenosis modifying specific features without eliminating broader patterns. Silicone models showed broad loops, latex models displayed complex crossing patterns, and vascular grafts exhibited narrow, near-linear loops. Loop morphology and the repeatable slope descriptor (α) were consistent across measurements, together differentiating the integrated, configuration-specific dynamic responses of the tested vascular models and grafts.

Conclusion: Pressure-pressure loop analysis provides a novel pressure-only framework for functional characterization of vascular models and grafts. Combining qualitative loop morphology with a reproducible quantitative slope descriptor, the approach captures complementary features of the integrated dynamic pressure response rather than a single intrinsic material property. The study demonstrates the feasibility of extracting meaningful descriptors from two intraluminal pressure waveforms in-vitro, supporting future validation in native blood vessels and applications in vascular graft design.