4D Flow MRI Following TCPC: Comparison of Kinetic Energy in the Ventricles of Patients with Extracardiac Conduit and Lateral Tunnel

Background: In this study we investigated differences in profiles of kinetic energy (KE) in the ventricles of patients with univentricular hearts after total cavopulmonary connection (TCPC) with extracardiac conduit (ECFT) or intraatrial-lateral tunnel (IAFT).

Methods: We prospectively examined 33 patients aged 19.8(14.6; 30.2) years [median (Q1; Q3)] after TCPC [14.3(9.7; 24.9) years after surgery] with a 4D-Flow sequence on a 3.0 T MRI scanner. Examinations in coronal orientation were performed with respiratory gating, voxel size 1.2 mm3, interpolated to 0.6 mm3, 224 slices per slab, FoV 460 × 460 mm (covering the heart and the large vessels near the heart). Mean scan time was 19:43 [15:01; 22:35] min. A special postprocessing software was used for segmentation of the ventricle and calculation of kinetic energy and vorticity. Over one cardiac cycle 20 measuring points were calculated and divided in systole, early-diastole and late-diastole. In addition, parameters of the annual routine check-up were evaluated. Statistical analysis was performed using U-test and Fisher´s exact test.

Results: A total of 18 patients (group 1) had an ECFT, 13 patients (group 2) an IAFT. Patients in group 1 were younger with 15.8 (12.8; 18.8) years versus 30 (26.0; 31.8) years, p = 0.001. Follow-up time (TCPC-MRI) was significantly shorter in group 1 with 10.4 (8.9; 13.4) versus 24.9 (23.1; 26.3) in group 2, p = 0.001. Waveform of late diastole could be delineated in 14 patients of group 1 and in 12 patients of group 2. Patients in group 1 showed lower peak values of KE in late diastole with 1,718 (1,231; 2,285) µJ versus 2938(2404; 3817) µJ in group 2, p = 0.003. In addition, patients in group 1 showed lower mean values of KE in late diastole with 1,367 (912; 1812) µJ versus 2,287 (1,809; 2,815) µJ in group 2, p = 0.003. These results were seen as well in absolute values of KE and KE normalized to SV and to BSA. In group 1 O2 pulse was lower with 8.1 (6.1; 9.8) versus 11.5 (8.1; 17) in group 2, p = 0.025. 5 patients in group 1 had protein-losing enteropathy versus none in group 2, p = 0.058.

Conclusion: Despite the complex anatomy of univentricular hearts, it was possible to determine the kinetic energy in the ventricle. The profile of KE in the ventricle differed in late diastole according to the type of the cavopulmonary connection probably due to a lower diastolic filling capacity. In our collective, patients with extracardiac conduit were significantly younger. Further studies are necessary to determine whether the differences in kinetic energy are due to differences in anatomy or depending on the time interval after TCPC.

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Artikel online veröffentlicht:
13. Februar 2024