Retrograde Embolism From the Descending Aorta: Visualization by Multidirectional 3D Velocity Mapping in Cryptogenic Stroke

Background and Purpose— The purpose of this study was to determine the role of plaques ≥4 mm and thrombi (complex plaques) in the descending aorta (DAo) as an embolic high-risk source for stroke. Methods— In 63 acute stroke patients scheduled for TEE, territory and embolic pattern of brain ischemia were prospectively assessed. Multidirectional 3D MRI velocity mapping of the aorta was performed to correlate the extent of retrograde diastolic blood flow with the distance of complex DAo plaques from the left subclavian artery (LSA). Embolic risk from the DAo was present for (1) retrograde flow connecting complex DAo plaques with the LSA, (2) embolic pattern of brain ischemia in a territory supplied by the left vertebral artery, and (3) stroke that could not be explained by other means. Results— 33 of 63 patients had complex DAo plaques (distance to LSA 28.1±29.9 mm). Mean retrograde flow in these subjects was 26.2±12.3 mm. In 20 of 63 patients (31.7%) retrograde flow connected complex DAo plaques with the LSA. In 4 of these 20 patients (20%) with an embolic stroke in the territory of the brain stem, cerebellum or posterior cerebral artery, etiology could not be explained by other means. Conclusions— Substantial diastolic retrograde flow originating from complex plaques in the descending aorta was detected by multidirectional 3D MRI velocity mapping and constitutes a stroke mechanism that was previously not demonstrable.