Markl Michael, Carr Maria, Ng Jason, Lee Daniel C, Jarvis Kelly, Carr James, Goldberger Jeffrey J
Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Avenue Suite 1600, Chicago, IL, 60611, USA.
Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, USA.
Int J Cardiovasc Imaging. 2016 May;32(5):807-15. doi: 10.1007/s10554-015-0830-8. Epub 2016 Jan 28.
Atrial fibrillation (AF) is associated with embolic stroke due to thrombus formation in the left atrium (LA). Based on the relationship of atrial stasis to thromboembolism and the marked disparity in pulmonary versus systemic thromboembolism in AF, we tested the hypothesis that flow velocity distributions in the left (LA) versus right atrium (RA) in patients with would demonstrate increased stasis. Whole heart 4D flow MRI was performed in 62 AF patients (n = 33 in sinus rhythm during imaging, n = 29 with persistent AF) and 8 controls for the assessment of in vivo atrial 3D blood flow. 3D segmentation of the LA and RA geometry and normalized velocity histograms assessed atrial velocity distribution and stasis (% of atrial velocities <0.2 m/s). Atrial hemodynamics were similar for RA and LA and significantly correlated (mean velocity: r = 0.64; stasis: r = 0.55, p < 0.001). RA and LA mean and median velocities were lower in AF patients by 15-33 % and stasis was elevated by 11-19 % compared to controls. There was high inter-individual variability in LA/RA mean velocity ratio (range 0.5-1.8) and LA/RA stasis ratio (range 0.7-1.7). Patients with a history of AF and in sinus rhythm showed most pronounced differences in atrial flow (reduced mean velocities, higher stasis in the LA). While there is no systematic difference in LA versus RA flow velocity profiles, high variability was noted. Further delineation of patient specific factors and/or regional atrial effects on the LA and RA flow velocity profiles, as well as other factors such as differences in procoagulant factors, may explain the more prevalent systemic versus pulmonary thromboembolism in patients with AF.
心房颤动（AF）与左心房（LA）血栓形成导致的栓塞性中风相关。基于心房淤滞与血栓栓塞的关系以及AF患者肺栓塞与系统性血栓栓塞的显著差异，我们检验了这样一个假设：AF患者左心房（LA）与右心房（RA）的血流速度分布会显示出淤滞增加。对62例AF患者（成像期间n = 33例处于窦性心律，n = 29例为持续性AF）和8例对照者进行了全心4D血流MRI检查，以评估体内心房三维血流情况。对LA和RA几何结构进行三维分割并绘制标准化速度直方图，以评估心房速度分布和淤滞情况（心房速度<0.2 m/s的百分比）。RA和LA的心房血流动力学相似且显著相关（平均速度：r = 0.64；淤滞：r = 0.55，p < 0.001）。与对照者相比，AF患者的RA和LA平均及中位数速度降低了15% - 33%，淤滞增加了11% - 19%。LA/RA平均速度比值（范围0.5 - 1.8）和LA/RA淤滞比值（范围0.7 - 1.7）存在较高的个体间变异性。有AF病史且处于窦性心律的患者心房血流差异最为明显（平均速度降低，LA淤滞增加）。虽然LA与RA血流速度剖面没有系统性差异，但变异性较高。进一步明确患者特定因素和/或区域心房对LA和RA血流速度剖面的影响，以及其他因素如促凝因子差异等，可能解释AF患者中系统性血栓栓塞比肺血栓栓塞更普遍的现象。
