Aortic Atherosclerosis Determines Increased Retrograde Blood Flow as a Potential Mechanism of Retrograde Embolic Stroke
2017-01-01

&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; 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. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; 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 (VTI&lt;sub&gt;retrograde&lt;/sub&gt;/VTI&lt;sub&gt;antegrade&lt;/sub&gt;) was used to estimate retrograde flow extent. Associations between patient demographics, cardiovascular risk factors, echocardiographic parameters, and VTI&lt;sub&gt;ratio&lt;/sub&gt; were analyzed using multivariate linear regression. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; Retrograde blood flow in the DAo occurred in all patients. Velocity profiles in the proximal DAo were as follows (mean ± SD): VTI&lt;sub&gt;antegrade&lt;/sub&gt; = 21.1 ± 6.5, VTI&lt;sub&gt;retrograde&lt;/sub&gt; = 11.0 ± 3.6, and VTI&lt;sub&gt;ratio&lt;/sub&gt; = 0.54 ± 0.16. Diameter (&lt;i&gt;r&lt;/i&gt; = 0.25, &lt;i&gt;p &lt; &lt;/i&gt;0.001), presence of complex plaques (&lt;i&gt;r&lt;/i&gt; = 0.12, &lt;i&gt;p&lt;/i&gt; = 0.007), and reduced strain of the DAo (&lt;i&gt;r&lt;/i&gt; = -0.23, &lt;i&gt;p &lt; &lt;/i&gt;0.001) had significant partial effects in a predictor model based on predefined variables, which predicted 26% (adjusted &lt;i&gt;R&lt;/i&gt;&lt;sup&gt;2&lt;/sup&gt; = 0.26) of the variance in VTI&lt;sub&gt;ratio&lt;/sub&gt;. A unit increase in the DAo diameter was associated with a 2% increase in VTI&lt;sub&gt;ratio&lt;/sub&gt; (95% CI 1-2.8%, &lt;i&gt;p &lt; &lt;/i&gt;0.001). Presence of complex plaques increased VTI&lt;sub&gt;ratio&lt;/sub&gt; by 7% (95% CI 2-13%, &lt;i&gt;p&lt;/i&gt; = 0.007) and an increase in strain by 0.1 indicated a decrease in VTI&lt;sub&gt;ratio&lt;/sub&gt; by about 11% (95% CI 6.2-15.5%, &lt;i&gt;p&lt;/i&gt; &lt; 0.001). Complex atheroma was found in the proximal DAo of 79 subjects, of which 40 (50.6%) had a VTI&lt;sub&gt;ratio&lt;/sub&gt; above average (VTI&lt;sub&gt;ratio&lt;/sub&gt; ≥0.54) compared to 87 of 261 (33.3%) patients without any complex plaques (&lt;i&gt;p &lt; &lt;/i&gt;0.001). Twenty-five of 79 (31.7%) patients with complex DAo plaques had a VTI&lt;sub&gt;ratio&lt;/sub&gt; ≥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. &lt;b&gt;&lt;i&gt;Conclusions:&lt;/i&gt;&lt;/b&gt; 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.