Incorporating Arterial Viscoelastic Modelling for the Assessment of Changes in Pulse Wave Velocity within a Cardiac Cycle Using Bramwell-Hill Equation

Abstract

Aims: This work presents a method & instrumentation to measure pressure-dependent intra-cardiac cycle variations in local blood pulse velocity PWV(P) using Bramwell-Hill (BH) equation by incorporating Kelvin-Voigt type viscoelastic modelling.Methods: A pilot in-vivo study on 8 subjects was conducted to verify the technique's functionality. The carotid diameter D and pressure P waveforms (sampled at 1 kHz) were measured using our extensively validated image-free ultrasound technology ARTSENS and a calibrated tonometer respectively.Results: Measurement system captured high fidelity P and D signals. Employing the viscoelastic modelling, elastic P-D curves were obtained and PWV(P) was calculated. The reliability of these curves was verified by comparing the stiffness index derived from the fit (βfit) against the theoretically calculated value βref which strongly correlated (r = 0.98, p < 0.05). The systolic PWV (PWVs) was approximately 20% higher than diastolic PWV (PWVd). The group average PWVs and PWVd were higher for hypertensive subjects. Conclusion: The proposed technique reliably measures the intra-cardiac cycle variations in PWV(P) and addresses various key considerations associated with non-invasive implementation BH equation for the same.

ARTSENS®Pen—portable easy-to-use device for carotid stiffness measurement: technology validation and clinical-utility assessment

“…The Y measurement ARTSENS ® Pen was developed to realize an affordable (<$500), portable, and minimal operator-dependent device that could perform automated measurements of such functional elastic properties from superficial arteries, with an accuracy that meets clinical standards. We have been further working on improving this technology to accommodate automatic measurement of properties such as incremental intrinsic elasticity (Raj et al 2018, Nabeel et al 2019, Raj et al 2019b, viscosity index and wall buffering function (Raj et al 2019a) that represent the direct material properties, which is beyond the scope of this article. The core image-free ultrasound technology, ARTSENS ® , was first proposed in 2008 (Joseph and Jayashankar 2008) and its principle was demonstrated via simulations, controlled phantom-based experiments (Joseph et al 2009, Joseph and Jayashankar 2008, and in-vivo studies (Joseph et al 2014(Joseph et al , 2015.…”