Estimation of Cardiovascular Relative Pressure Using Virtual Work-Energy

Abstract

Many cardiovascular diseases lead to local increases in relative pressure, reflecting the higher costs of driving blood flow. The utility of this biomarker for stratifying the severity of disease has thus driven the development of methods to measure these relative pressures. While intravascular catheterisation remains the most direct measure, its invasiveness limits clinical application in many instances. Non-invasive Doppler ultrasound estimates have partially addressed this gap; however only provide relative pressure estimates for a range of constricted cardiovascular conditions. Here we introduce a non-invasive method that enables arbitrary interrogation of relative pressures throughout an imaged vascular structure, leveraging modern phase contrast magnetic resonance imaging, the virtual work-energy equations, and a virtual field to provide robust and accurate estimates. The versatility and accuracy of the method is verified in a set of complex patient-specific cardiovascular models, where relative pressures into previously inaccessible flow regions are assessed. The method is further validated within a cohort of congenital heart disease patients, providing a novel tool for probing relative pressures in-vivo.

False lumen pressure estimation in type B aortic dissection using 4D flow cardiovascular magnetic resonance: comparisons with aortic growth

“…While FLEF and MSDR are proposed as indirect measures of FL pressure, recent developments in physics-based image analysis now enable the accurate extraction of relative pressure over vascular sections. v WERP is a validated method for relative pressure measurement that utilizes the concept of virtual work-energy, which has shown particular promise in assessing complex vasculatures and has been explicitly tested in TBAD anatomy [ 25 ]. As such, the FL ΔP max represents a global and direct measure of change in pressure from the ascending aorta to the distal thoracic FL.…”

“…3 ), although it's unclear if such small differences in strength of correlation are meaningful or simply related to statistical noise. The simplicity in derivation makes FLEF an attractive metric in clinical instances where the FL has a single dominant tear in the thoracic aorta, whereas v WERP may be better suited in scenarios with multiple or complex flap fenestrations/tears (as shown in previous in-silico work [ 25 ]. Regardless of the metric, our analysis underlines the pathophysiological importance of FL pressurization in TBAD growth, adding to the increasing number of studies highlighting its diagnostic role [ 10 – 13 , 18 , 24 , 33 ].…”

“…vWERP relative pressure analysis : v WERP was used to assess the development of intraaortic pressure through the TL and FL [ 25 ]. The registered segmentations of TL and FL were used as input, with both segmentations connected to the proximal undissected ascending aorta.…”

“…The registered segmentations of TL and FL were used as input, with both segmentations connected to the proximal undissected ascending aorta. Relative aortic pressure changes were computed for the TL and FL over a segment from the ascending aorta to the distal FL at the level of the diaphragm (see Additional file 1 : Appendix A and Marlevi et al [ 25 ] for technical method details). To account for potential differences in intersubject anatomy, relative pressure traces were normalized by aortic length.…”

“…However, recent technical advancements in physics-based image analysis have allowed for non-invasive measurement of intravascular pressure drop from 4D Flow data. v WERP (virtual Work-Energy Relative Pressure) is such a technique, which uses a virtual work-energy formulation of the Navier–Stokes equations to provide accurate estimates of relative pressure through complex vascular anatomies [ 25 ]. v WERP has even been shown to provide accurate measurements (errors of < 1 mmHg) of relative pressure in the TL and FL in-silico, and has been validated against invasive catheterization in-vivo [ 25 ].…”