Non-invasive estimation of vascular compliance and distensibility in the arm vessels: a novel ultrasound-based protocol

Cappelletti S, Caimi A, Caldiroli A, Baroni I, Votta E, Riboldi SA, Marrocco-Trischitta MM, Redaelli A, Sturla F. Non-invasive estimation of vascular compliance and distensibility in the arm vessels: a novel ultrasound-based protocol. Quant Imaging Med Surg. 2022 Jul;12(7):3515-3527. doi: 10.21037/qims-21-987. PMID: 35782271; PMCID: PMC9246759. <strong>Abstract</strong> <strong>Background: </strong>Performance and durability of arterio-venous grafts depend on their ability to mimic the mechanical behavior of the anastomized blood vessels. To select the most suitable synthetic graft, <em>in vivo</em> evaluation of the radial deformability of peripheral arteries and veins could be crucial; however, a standardized non-invasive strategy is still missing. Herein, we sought to define a novel and user-friendly clinical protocol for <em>in vivo</em> assessment of the arm vessel deformability. <strong>Methods: </strong>A dedicated protocol, applied on 30 volunteers, was specifically designed to estimate both compliance and distensibility of the brachial and radial arteries, and of the basilic and cephalic veins. Bi-dimensional ultrasound imaging was used to acquire cross-sectional areas (CSAs) of arteries in clinostatic configuration, and CSAs of veins combining clinostatic and orthostatic configurations. Arterial pulse pressure was measured with a digital sphygmomanometer, while venous hydrostatic pressure was derived from the arm length in orthostatic configuration. <strong>Results: </strong>For each participant, all CSAs were successfully extracted from ultrasound images. The basilic vein and the radial artery exhibited the largest (21.5±8.9 mm²) and the smallest (3.4±1.0 mm²) CSAs, respectively; CSA measurements were highly repeatable (Bland-Altman bias &lt;10% and Pearson correlation ≥0.90, for both arteries and veins). In veins, compliance and distensibility were higher than in arteries; compliance was significantly higher (P&lt;0.0001) in the brachial than in the radial artery (3.52×10^-4 <em>vs.</em> 1.3×10^-4 cm²/mmHg); it was three times larger in basilic veins than in cephalic veins (17.4×10^-4 <em>vs.</em> 5.6×10^-4 cm²/mmHg, P&lt;0.0001). <strong>Conclusions: </strong>The proposed non-invasive protocol proved feasible, effective and adequate for daily clinical practice, allowing for the estimation of patient-specific compliance and distensibility of peripheral arteries and veins. If further extended, it may contribute to the fabrication of biohybrid arterio-venous grafts, paving the way towards patient-tailored solutions for vascular access.