4D Flow MRI Following TCPC: Comparison of the Kinetic Energy of Blood in the Ventricles of Patients with a Systemic Right and a Systemic Left Ventricle

Background: In this study, we investigated differences in profiles of kinetic energy (KE) of blood inside the ventricles of patients with univentricular hearts (UVH) after total cavopulmonary connection (TCPC) according to the morphology of the ventricle in the systemic left ventricle (LV) and systemic right ventricle (RV).

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 2.5 mm³, 64 slices per slab, FoV 300 × 400 × 160 mm³ (covering the heart and the large vessels near the heart). The mean scan time was 19:43 (15:01; 22:35) minutes. A special postprocessing software was used for segmentation of the ventricle and calculation of KE. Over one cardiac cycle 20 measuring points were calculated and divided into systole, early diastole, and late diastole. In addition, the parameters of the annual routine checkup were evaluated. Statistical analysis was performed using U-test and Fisher’s exact test.

Results: Twenty-one patients (group 1) had an LV, and 12 patients (group 2) had an RV. There were no significant differences regarding age, follow-up time after TCPC, BSA, or type of tunnel between both groups. Absolute KE values were normalized to stroke volume. Patients in group 1 showed lower peak values of KE in systole with 80 (72–103) versus 120 (96–137) μJ/mL in group 2, p = 0.006, lower peak values in early diastole with 40 (31–56) versus 60 (46–117) μJ/mL in group 2, p = 0.010, and lower peak values in late diastole with 31 (25–42) versus 42 (33–61) μL/mL in group 2, p = 0.049. Patients in group 1 showed lower mean values in systole 46 (40–59) versus 72 (60–91) μJ/mL in group 2, p < 0.001, and lower mean values in total diastole with 26 (23; 33) versus 40 (30–46) μJ/mL in group 2, p = 0.007. Patients in group 1 received significantly less β-blocker medication (23.8% vs. 66.7%, p = 0.027) and sildenafil (4.8% vs. 33.2%, p = 0.047). In the treadmill, VO_2max showed trends toward higher values in group 1 with 25.2 (22.9–31.2) versus 22.4 (19–25) mL/kg/min in group 2, p = 0.095 and trends in O₂ pulse with 10.15 (7.93–15.73) versus 8.6 (5.1–9.9) mL in group 2, p = 0.066. History of plastic bronchitis occurred in no patient in group 1 and in 4 patients in group 2 (p = 0.012).

Conclusion: KE of blood inside ventricles in patients with morphological LV was lower compared with those with morphological RV, probably as a reflection of higher myocardial efficiency of the LV in the systemic position.

Publikationsverlauf

Artikel online veröffentlicht:
11. Februar 2025