Department of Vascular Surgery, Haga Teaching Hospital, The Hague, the Netherlands.
Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands.
Vasc Endovascular Surg. 2021 Oct;55(7):696-701. doi: 10.1177/15385744211017117. Epub 2021 Jun 3.
Four-dimensional flow magnetic resonance imaging (4D flow MRI) can accurately visualize and quantify flow and provide hemodynamic information such as wall shear stress (WSS). This imaging technique can be used to obtain more insight in the hemodynamic changes during cardiac cycle in the true and false lumen of uncomplicated acute Type B Aortic Dissection (TBAD). Gaining more insight of these forces in the false lumen in uncomplicated TBAD during optimal medical treatment, might result in prediction of adverse outcomes.
A porcine aorta dissection model with an artificial dissection was positioned in a validated ex-vivo circulatory system with physiological pulsatile flow. 4D flow MR images with 3 set heartrates (HR; 60 bpm, 80 bpm and 100 bpm) were acquired. False lumen volume per cycle (FLV), mean and peak systolic WSS were determined from 4D flow MRI data. For validation, the experiment was repeated with a second porcine aorta dissection model.
During both experiments an increase in FLV (initial experiment: ΔFLV = 2.05 ml, , repeated experiment: ΔFLV = 1.08 ml, ) and peak WSS (initial experiment: ΔWSS = 1.2 Pa, , repeated experiment: ΔWSS = 1.79 Pa, ) was observed when HR increased from 60 to 80 bpm. Raising the HR from 80 to 100 bpm, no significant increase in FLV () was seen during both experiments. The false lumen mean WSS increased significant during initial (2.71 to 3.85 Pa; ) and non-significant during repeated experiment (3.22 to 4.00 Pa; ).
4D flow MRI provides insight into hemodynamic dimensions including WSS. Our ex-vivo experiments showed that an increase in HR from 60 to 80 bpm resulted in a significant increase of FLV and WSS of the false lumen. We suggest that strict heart rate control is of major importance to reduce the mean and peak WSS in uncomplicated acute TBAD. Because of the limitations of an ex-vivo study, 4D flow MRI will have to be performed in clinical setting to determine whether this imaging model would be of value to predict the course of uncomplicated TBAD.
四维流磁共振成像（4D flow MRI）可以准确地可视化和量化血流，并提供壁切应力（WSS）等血流动力学信息。这项成像技术可用于深入了解非复杂性急性 B 型主动脉夹层（TBAD）真腔和假腔中的血流动力学变化。在接受最佳药物治疗的非复杂性 TBAD 中，对假腔中的这些力有更深入的了解，可能会预测不良结局。
将具有人工夹层的猪主动脉夹层模型置于具有生理脉动流的经验证的离体循环系统中。采集 3 组心率（HR；60 次/分、80 次/分和 100 次/分）的 4D flow MRI 图像。从 4D flow MRI 数据中确定假腔容积/心动周期（FLV）、平均和峰值收缩期 WSS。为了验证，在第二个猪主动脉夹层模型中重复了该实验。
在两次实验中，当心率从 60 次/分增加到 80 次/分时，FLV（初始实验：ΔFLV=2.05ml，；重复实验：ΔFLV=1.08ml，）和峰值 WSS（初始实验：ΔWSS=1.2Pa，；重复实验：ΔWSS=1.79Pa，）增加。当心率从 80 次/分增加到 100 次/分时，两次实验中 FLV 均无显著增加（）。假腔平均 WSS在初始实验中显著增加（2.71 至 3.85Pa；），在重复实验中无显著增加（3.22 至 4.00Pa；）。
4D flow MRI 提供了包括 WSS 在内的血流动力学参数的深入了解。我们的离体实验表明，心率从 60 次/分增加到 80 次/分导致假腔 FLV 和 WSS 显著增加。我们建议严格控制心率对于降低非复杂性急性 TBAD 中的平均和峰值 WSS 非常重要。由于离体研究的局限性，需要在临床环境中进行 4D flow MRI 以确定该成像模型是否有助于预测非复杂性 TBAD 的病程。
