Contralateral retrograde flow diverter deployment for vertebral artery dissection after failed anterograde access: technical note

Objective Flow diverter deployment for vertebral artery (VA) dissecting aneurysms is typically performed via an anterograde ipsilateral approach, but this strategy may be unsafe or unfeasible in the presence of true lumen collapse or intraluminal thrombus. How and when to convert to a contralateral retrograde approach after failed anterograde access remains poorly defined. We report a case of contralateral retrograde flow diverter deployment and propose anatomical and procedural considerations for this conversion. Methods A 58-year-old woman with a right V4 dissecting aneurysm underwent elective flow diversion. After anterograde catheterisation failed because a dissected segment of the right VA could not be traversed and thrombus formed, a contralateral retrograde approach was performed via the left VA and basilar artery. A 3.5 × 25 mm Pipeline Embolization Device (PED; Medtronic, Irvine, California, USA) was deployed across the lesion. We considered vertebrobasilar junction angle, contralateral VA calibre, and basilar artery patency as practical anatomical considerations relevant to retrograde access. Results Retrograde PED deployment was technically successful. Postoperative MRI showed multifocal posterior-circulation embolic infarcts; the resulting alexia without agraphia and right visual-field defect improved. Follow-up angiography at 6 and 12 months demonstrated progressive reduction in aneurysm filling with preserved vertebrobasilar flow. The vertebrobasilar junction angle was approximately 76°. Conclusions Contralateral retrograde flow diverter deployment is an option when anterograde access to a VA dissecting aneurysm cannot be achieved, but it may be complicated by posterior-circulation thromboembolism, particularly when the ipsilateral VA contains thrombus. Pre-procedural anatomical assessment, confirmation of the antiplatelet response, and early recognition of anterograde failure are important considerations.