In vivo retrieval of a trapped Merci embolectomy device: technical case report

This technical note describes a complication related to the use of the Merci embolectomy device not previously reported. The device can induce critical flow limitation within an accessed vessel because of a combination of vasospasm and anatomic conformational changes. Furthermore, this can limit the safe removal of the device from intracranial vasculature. We present a novel rescue technique that can be used to safely retrieve the entrapped Merci device without inciting localized vessel injury.

A 51-year-old male with embolic occlusion of the distal basilar artery and dissection-related occlusion of the left cervical vertebral underwent mechanical thrombolysis. Flow-limiting vasospasm and/or anatomic conformational changes/ telescoping of the intracranial right vertebral artery segment was induced during deployment with subsequent entrapment of the device. Reclamation of the entrapped device was performed by initially removing the Merci microcatheter. The entrapped and fixated device was then resheathed into a 4F slip catheter within the intracranial vertebral artery. The Merci device and the slip catheter were then removed. Right vertebral and proximal basilar artery flow was reestablished after removal of the Merci device. Successful clot extraction was thereafter performed using a microsnare.

In vitro assessment of the device has demonstrated its propensity to induce vasospasm. In vivo entrapment of the device has not been previously reported. Successful retrieval can be achieved if the Merci device becomes entrapped and fixated. This may be an important consideration as increased utilization of the device occurs.