P588Flow profile for a better non-invasive pressure drop in CoA

Abstract

Abstract Introduction In cardiovascular obstructions, as Coarctation of the Aorta (CoA), guidelines recommend treatment based on a relevant pressure drop (ΔP). Diagnostic ΔP is estimated by simplified Bernoulli (SB) and is measured as peak-to-peak (PtP) ΔP via catheterization. The divergences amid methods are understood, but it is common practice to widely and positively accept both as valid diagnostic. Recently, simplified advective work-energy relative pressure (SAW) to correct SB by considering the full velocity profile for the ΔP computation. Purpose To verify the correctness of peak flow derived pressure drop via maximal velocity (SB), and full flow profile (SAW) versus clinical gold-standard PtP ΔP in a CoA phantom. Methods An MRI-compatible and pulsatile CoA phantom was built and tested in eight configurations, with four levels of obstruction (9, 11 and 13 mm CoA diameter and no CoA) under two flow regimes (stress and normal). The ΔP was measured via catheterization between ascending and in descending aorta (DA) as instantaneous and as PtP. Also, MRI 4D-flow velocity vector fields were acquired, enabling the ΔP estimation by SB and SAW at effective orifice area (EOA) and DA catheterization locations. at the point of the effective orifice area (EOA) and at DA catheterization location. Results The disparity in ΔP illustrate the fundamental differences between methods (figure and table). Catheterised instant and PtP ΔPs are similar for the CoA phantom configurations, where SB and SAW are valid. The lesser the obstruction, the greater is the temporal acceleration contribution to the ΔP and discrepancies between methods arise. As recognised, SB is an overestimation of the catheterization measurements. The most equivalent ΔPs are the catheterization PtP and SAW. Velocity-based ΔPs (SB and SAW) show a drop in performance when the velocity is captured at the DA instead of the right EOA point, illustrating the sensitivity to the acquisition location. Peak ΔPs per method and per phantom 9mm CoA 11mm CoA 13mm CoA Normal R2 Linear eq. rest stress rest stress rest stress rest stress Instant ΔP 33.4 45.7 11.5 19.6 12.1 14.5 −2.7 −12.2 0.949 y=1.12x PtP ΔP 29.3 43.5 10.0 16.0 5.8 11.2 −1.8 -3.6 – – SB EOA 37.5 52.3 13.4 22.3 6.1 11.4 1.4 1.4 0.988 y=1.23x SB DA 22.6 59.8 10.7 18.6 5.2 8.5 0.9 1.2 0.893 y=1.15x SAW EOA 29.9 51.4 11.3 19.0 4.9 9.7 0.8 0.8 0.972 y=1.11x SAW DA 11.74 28.3 5.5 9.9 2.7 4.5 0.6 0.7 0.911 y=0.56x Linear comparisons were made against gold-standard catheterised PtP ΔP. Velocity meshes and ΔPs in cardiac cycle Conclusions Initial phantom evidence suggests that the non-invasive ΔP assessments based on flow should consider the full flow profile and be acquired at the point of EOA. Acknowledgement/Funding PIC project, European Union's Horizon 2020 Marie Skłodowska-Curie ITN Project under grant agreement No 764738