Assessment of ventricular flow dynamics by 4D-flow MRI in patients following surgical repair of d-transposition of the great arteries

Abstract

Objectives To use 4D-flow MRI to describe systemic and non-systemic ventricular flow organisation and energy loss in patients with repaired d-transposition of the great arteries (d-TGA) and normal subjects. Methods Pathline tracking of ventricular volumes was performed using 4D-flow MRI data from a 1.5-T GE Discovery MR450 scanner. D-TGA patients following arterial switch (n = 17, mean age 14 ± 5 years) and atrial switch (n = 15, 35 ± 6 years) procedures were examined and compared with subjects with normal cardiac anatomy and ventricular function (n = 12, 12 ± 3 years). Pathlines were classified by their passage through the ventricles as direct flow, retained inflow, delayed ejection flow, and residual volume and visually and quantitatively assessed. Additionally, viscous energy losses (ELv) were calculated. Results In normal subjects, the ventricular flow paths were well ordered following similar trajectories through the ventricles with very little mixing of flow components. The flow paths in all atrial and some arterial switch patients were more irregular with high mixing. Direct flow and delayed ejection flow were decreased in atrial switch patients’ systemic ventricles with a corresponding increase in residual volume compared with normal subjects (p = 0.003 and p < 0.001 respectively) and arterial switch patients (p < 0.0001 and p < 0.001 respectively). In non-systemic ventricles, arterial switch patients had increased direct flow and decreased delayed ejection fractions compared to normal (p = 0.007 and p < 0.001 respectively) and atrial switch patients (p = 0.01 and p < 0.001 respectively). Regions of high levels of mixing of ventricular flow components showed elevated ELv. Conclusions 4D-flow MRI pathline tracking reveals disordered ventricular flow patterns and associated ELv in d-TGA patients. Key Points • 4D-flow MRI can be used to assess intraventricular flow dynamics in d-TGA patients. • d-TGA arterial switch patients mostly show intraventricular flow dynamics representative of normal subjects, while atrial switch patients show increased flow disorder and different proportions of intraventricular flow volumes. • Flow disruption and disorder increase viscous energy losses.

4D Flow cardiovascular magnetic resonance consensus statement: 2023 update

“…Several clinical centres use the following guidance: If acquiring 4D Flow CMR directly after gadolinium administration, it is advisable to increase the flip angle to 15–25° 1.5T and 12° at 3T. [ 29 , 49 , 53 ]. If 4D Flow CMR is acquired after LGE a lower flip angle (similar to non-contrast values) is likely needed.…”

Advances in machine learning applications for cardiovascular 4D flow MRI

“…The quantification of net flow and peak velocities from 4D flow MRI has shown to be of diagnostic relevance for cardiovascular diseases such as the grading of stenoses, aortic coarctation, or aortic-and mitral valve regurgitation (6)(7)(8)(9). Also, the visualization of the direction of the blood flow is important, for example in aortic aneurysms, aortic dissections and coarctations, in hypertrophy cardiomyopathy (6,10), as well as in congenital heart disease, such as univentricular hearts or transposition of the great arteries (11,12). Moreover, 4D flow MRI allows the direct quantification of regurgitant flow compared to traditional indirect methods (i.e., subtracting stroke volume calculated from aortic 2D flow MRI from stroke volume measured by left ventricular segmentation) in mitral valve insufficiency (13).…”

Braids in the heart: global measures of mixing for cardiovascular flows

“…The flow in the healthy left ventricle remains a good example. The three-dimensional flow has been investigated by several research groups, mainly through numerical simulation (Badas, Domenichini, & Querzoli, 2017; Khalavfand, Xu, Westenberg, Gijsen & Kenjeres, 2019; Lantz et al., 2021; Lantz, Henriksson, Persson, Karlsson & Ebbers, 2016; Mangual et al., 2013; Meschini, de Tullio, Querzoli, & Verzicco, 2018; Pedrizzetti & Domenichini, 2005; Sacco et al., 2018; Seo & Mittal, 2013) but also through in vivo (Callaghan, Burkhardt, Valsangiacomo Buechel, Kellenberger & Geiger, 2021; Costello et al., 2018; Eriksson, Bolger, Ebbers, & Carlhäll, 2013; Voorneveld et al., 2020) and in vitro (Fortini, Querzoli, Espa, & Cenedese, 2013; Saaid et al., 2019) studies. While these studies have highlighted the value of the full three-dimensional flow, the observed large-scale dynamics still consists of a global swirling motion that is well captured by the plane shown in figures 1 and 3, namely, one bisecting the valve centres and the ventricle apex.…”

“…While these studies have highlighted the value of the full three-dimensional flow, the observed large-scale dynamics still consists of a global swirling motion that is well captured by the plane shown in figures 1 and 3, namely, one bisecting the valve centres and the ventricle apex. The particle trajectories, which are predominantly influenced by the larger-scale dynamics, appear to be quasi-two-dimensional in the vicinity of this plane (Badas et al., 2017; Callaghan et al., 2021; Eriksson et al., 2013; Seo & Mittal, 2013). Furthermore, several quantitative and qualitative physical features important to particle trajectories (e.g.…”