Wehrum Thomas, Guenther Felix, Vach Werner, Gladstone Beryl Primrose, Wendel Sarah, Fuchs Alexander, Wu Kehzong, Maurer Christoph Johannes, Harloff Andreas
Department of Neurology, University Medical Center Freiburg, Freiburg, Germany.
Cerebrovasc Dis. 2017;43(3-4):132-138. doi: 10.1159/000455053. Epub 2017 Jan 4.
Retrograde brain embolization from complex plaques of the proximal descending aorta (DAo) has been identified as a new potential mechanism of stroke. Our purpose was to identify predictors of increased retrograde aortic blood flow indicating an elevated risk of brain embolization from the DAo.
A total of 485 patients with acute ischemic stroke were prospectively included and underwent transesophageal echocardiography. Blood flow velocities in the proximal DAo were studied using 2D pulse-wave Doppler ultrasound. Velocity-time integrals (VTI) were calculated for antegrade and retrograde velocity directions. The ratio (VTIretrograde/VTIantegrade) was used to estimate retrograde flow extent. Associations between patient demographics, cardiovascular risk factors, echocardiographic parameters, and VTIratio were analyzed using multivariate linear regression.
Retrograde blood flow in the DAo occurred in all patients. Velocity profiles in the proximal DAo were as follows (mean ± SD): VTIantegrade = 21.1 ± 6.5, VTIretrograde = 11.0 ± 3.6, and VTIratio = 0.54 ± 0.16. Diameter (r = 0.25, p < 0.001), presence of complex plaques (r = 0.12, p = 0.007), and reduced strain of the DAo (r = -0.23, p < 0.001) had significant partial effects in a predictor model based on predefined variables, which predicted 26% (adjusted R2 = 0.26) of the variance in VTIratio. A unit increase in the DAo diameter was associated with a 2% increase in VTIratio (95% CI 1-2.8%, p < 0.001). Presence of complex plaques increased VTIratio by 7% (95% CI 2-13%, p = 0.007) and an increase in strain by 0.1 indicated a decrease in VTIratio by about 11% (95% CI 6.2-15.5%, p < 0.001). Complex atheroma was found in the proximal DAo of 79 subjects, of which 40 (50.6%) had a VTIratio above average (VTIratio ≥0.54) compared to 87 of 261 (33.3%) patients without any complex plaques (p < 0.001). Twenty-five of 79 (31.7%) patients with complex DAo plaques had a VTIratio ≥0.60, which indicates a high likelihood of retrograde pathline length of ≥3 cm and thus increased risk of retrograde cerebral embolization. Stroke etiology of those 25 patients was determined in 13 and cryptogenic in 12 cases.
Retrograde blood flow in the DAo was found in all stroke patients. However, it increased further in patients with concomitant complex plaques, low strain, and/or large aortic diameter, that is, in those with atherosclerosis of the DAo. Accordingly, such patients may be predisposed to retrograde embolization in case of occurrence of a complex plaque in proximity to a brain-supplying artery.
来自降主动脉近端（DAo）复杂斑块的逆行性脑栓塞已被确定为一种新的潜在卒中机制。我们的目的是确定逆行主动脉血流增加的预测因素，这表明DAo发生脑栓塞的风险升高。
前瞻性纳入485例急性缺血性卒中患者，并进行经食管超声心动图检查。使用二维脉冲波多普勒超声研究DAo近端的血流速度。计算顺行和逆行速度方向的速度时间积分（VTI）。比率（VTI逆行/VTI顺行）用于估计逆行血流程度。使用多元线性回归分析患者人口统计学、心血管危险因素、超声心动图参数和VTI比率之间的关联。
所有患者均出现DAo逆行血流。DAo近端的速度分布如下（平均值±标准差）：VTI顺行=21.1±6.5，VTI逆行=11.0±3.6，VTI比率=0.54±0.16。在基于预定义变量的预测模型中，直径（r=0.25，p<0.001）、复杂斑块的存在（r=0.12，p=0.007）和DAo应变降低（r=-0.23，p<0.001）具有显著的部分效应，该模型预测了VTI比率方差的26%（调整后R2=0.26）。DAo直径每增加一个单位，VTI比率增加2%（95%CI 1-2.8%，p<0.001）。复杂斑块的存在使VTI比率增加7%（95%CI 2-13%，p=0.007），应变增加0.1表明VTI比率降低约11%（95%CI 6.2-15.5%，p<0.001）。在79名受试者的DAo近端发现复杂动脉粥样硬化，其中40名（50.6%）的VTI比率高于平均水平（VTI比率≥0.54），而261名（33.3%）无任何复杂斑块的患者中有87名（p<0.001）。79名DAo复杂斑块患者中有25名（31.7%）的VTI比率≥0.60，这表明逆行路径长度≥3 cm的可能性很高，因此逆行性脑栓塞风险增加。这25例患者中13例确定了卒中病因，12例为隐源性。
在所有卒中患者中均发现DAo逆行血流。然而，在伴有复杂斑块、低应变和/或主动脉直径较大的患者中，即DAo动脉粥样硬化患者中，逆行血流进一步增加。因此，此类患者在供应脑动脉附近出现复杂斑块时可能易发生逆行栓塞。
