Division of Cardiology, Department of Pediatrics, Heart Institute, Children's Hospital Colorado, University of Colorado Denver | Anschutz Medical Campus, 13123 E 16th Ave, Aurora, CO, 80045-2560, USA.
Department of Radiology, Children's Hospital Colorado, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA.
Eur Radiol. 2023 Jan;33(1):302-311. doi: 10.1007/s00330-022-09017-6. Epub 2022 Jul 19.
Flow through the proximal pulmonary arteries (PAs) of patients with repaired Tetralogy of Fallot (TOF) is known to be highly disordered and associated with significant regurgitation. The purpose of this study was to evaluate 4D-Flow MRI-derived viscous energy loss [Formula: see text])-as a result of non-efficient flow propagation, and relate this parameter to standard right ventricular (RV) size and function markers in patients with repaired TOF.
Thirty-five patients with TOF and 14 controls underwent comprehensive 4D-Flow MRI evaluation for qualitative flow analysis and to calculate [Formula: see text] in the main and right pulmonary arteries. Sampled [Formula: see text] indices were correlated with the MRI-derived RV size and functional indices.
All patients with TOF exhibited abnormal, supra-physiologic helical/vortical formations in the PAs. Patients with TOF had significantly increased peak systolic [Formula: see text] (8.0 vs 0.5 mW, p < 0.001), time-averaged [Formula: see text] (2.5 vs. 0.2 mW, p < 0.001), and peak systolic [Formula: see text] indexed to stroke volume (0.082 vs. 0.012 mW/mL, p < 0.001). [Formula: see text] indexed to stroke volume correlated with the RV end-diastolic volume (R = 0.68, p < 0.001), end-systolic volume (R = 0.62, p < 0.001), ejection fraction (R = -0.45, p = 0.002), and cardiac index (R = 0.45, p = 0.002). The mean estimated energy loss due to [Formula: see text] with regard to input RV mechanical power was 4.7%.
This study demonstrates that patients with repaired TOF have highly abnormal flow conduction through the PAs which result into extensive viscous energy loss. This significant flow-mediated energy loss is associated with the RV volume and function, and might represent considerable loss of mechanical power generated by each cardiac cycle. Future studies are required to assess whether the abnormal flow conduction adds to the RV afterload and remodeling.
• Abnormal flow patterns through proximal pulmonary arteries in patients with TOF are associated with excessive viscous energy loss. • Inefficient flow conduction is associated with the RV dilation and reduced function and might contribute to the RV adaptive remodeling.
已知法洛四联症（TOF）修复术后患者近端肺动脉（PA）内血流呈高度紊乱状态，且伴大量反流。本研究旨在通过评估 4D-Flow MRI 衍生的粘性能量损耗（[Formula: see text]）——由于非有效血流传播所致，并将该参数与 TOF 修复术后患者的标准右心室（RV）大小和功能标志物相关联。
35 例 TOF 患者和 14 例对照者接受了全面的 4D-Flow MRI 评估，以进行定性的血流分析并计算主肺动脉和右肺动脉内的[Formula: see text]。对采样的[Formula: see text]指标与 MRI 衍生的 RV 大小和功能指数进行相关性分析。
所有 TOF 患者的 PA 内均出现异常的、超生理的螺旋/涡流形成。TOF 患者的收缩期峰值[Formula: see text]（8.0 比 0.5 mW，p < 0.001）、平均[Formula: see text]（2.5 比 0.2 mW，p < 0.001）和收缩期峰值[Formula: see text]与每搏量之比（0.082 比 0.012 mW/mL，p < 0.001）均显著增加。[Formula: see text]与每搏量之比与 RV 舒张末期容积（R = 0.68，p < 0.001）、收缩末期容积（R = 0.62，p < 0.001）、射血分数（R = -0.45，p = 0.002）和心指数（R = 0.45，p = 0.002）相关。由于[Formula: see text]导致的平均估计能量损耗占输入 RV 机械功率的 4.7%。
本研究表明，TOF 修复术后患者的 PA 内血流传导呈高度异常状态，导致广泛的粘性能量损耗。这种显著的血流介导的能量损耗与 RV 容积和功能相关，可能代表着每个心动周期产生的机械功率的大量损失。需要进一步的研究来评估异常的血流传导是否会增加 RV 的后负荷和重塑。
• TOF 患者近端肺动脉内的异常血流模式与过多的粘性能量损耗相关。
• 低效的血流传导与 RV 扩张和功能下降相关，并可能导致 RV 适应性重塑。
