1337486 - Evaluation of Altered Hemodynamics in Asymptomatic Patients after Arterial Switch Operation for Transposition of the Great Arteries：a 4D flow CMR Study

Patients with complete transposition of the great arteries (D-TGA) have an excellent overall long-term survival after arterial switch operation (ASO). Life-long monitoring of biventricular function is required to detect potential functional deterioration late after the ASO. Because of the pathophysiological mechanisms for residual neo-aortic regurgitation and pulmonary artery stenosis after operation remain unknown and need careful follow-up in these patients. We aimed to compare hemodynamic parameter differences between D-TGA patients and age- and gender- matched controls. and to investigate the association of hemodynamic parameters with conventional ventricular volumetric.

Methods:

Twenty-seven patients with D-TGA with intact ventricular septum or D-TGA with ventricular septal defect (VSD) were prospectively recruited in this study between July 2017 and June 2022. The MRI study design was described in Figure 1.  Inclusion criterion: 1. No previous interventional management such as surgical or catheterization procedures at least in last three years. 2. Asymptomatic; All had LV ejection fraction (EF) ≥ 50%, RVEF ≥ 45% by echocardiography in recent weeks. The D-TGA patients were divided into supravalvular pulmonary stenosis and non-supravalvular pulmonary groups. The D-TGA patients were divided into stenosis neoaortic regurgitation and non-neoaortic regurgitation groups.

The emitted pathlines generated from 4D flow postprocessing were divided into four functional blood flow components and the KE was computed which was presented in Figure 2. Since vorticity magnitude represented the local spinning motion of a fluid near a point, vorticity was computed by the formula ω = ∇ × V, where ∇ was the curl of its velocity field V and was calculated using a compact derivative algorithm.

Results:

Full demographic and ventricle volumetric details were provided in Table 1.

Delayed ejection flow, average KEi_EDV, peak systolic, systolic, peak E-wave KEi_EDV and peak A-wave KEi_EDV had significantly increased in D-TGA patients (Table 2). For RV, the vorticity parameters of D-TGA patients had not significantly increased compared to controls (Figure 3). For RV, the spravalvular pulmonary patients’ group had significantly decreased delayed ejection flow and increased Average KEi_EDV, Peak systolic KEi_EDV, Diastolic KEi_EDV, Peak E-wave KEi_EDV and Peak A-wave KE_iEDV compared to non-supravalvular pulmonary patients’ group (Figure 3). Based on multivariate analysis, diastolic KEi_EDV, peak E-wave KEi_EDV peak A-wave KEi_EDV and average vorticity were multivariable multicollinearity associated with RV moderate and severe RV afterload (Figure 3).

Conclusion:

4D flow MRI led to better knowledge of cardiovascular hemodynamics and disease progression in patients with D-TGA-related aortopathy. Diastolic KEi_EDV and average vorticity were multivariable associated with RV moderate and severe RV afterload.