Such embolic events may worsen the patient’s neurological condition. Therefore, distal thrombectomy devices are regularly

used in combination with proximal balloon occlusion in the internal carotid artery in conjunction with aspiration from the guiding catheter in order to reduce the risk of thromboembolic events during retrieval. Furthermore, vasospasm and vessel wall damage have been reported more frequently in association with distal thrombectomy devices. Various distal thrombectomy devices with brush-like, basket-like or coil-like designs have been advocated in the past (e.g. Catch, Balt, Montmorency, France; Phenox pCR and CRC, Bochum, Germany), with most of them only available in Europe. The largest clinical experience has JNK inhibitor been reported on the Merci Retrieval System (Concentric Medical, Mountain View, USA), which is the first device of this group to receive FDA approval in 2004. The Bortezomib mouse Merci Retrieval System is somehow the pioneer of intracranial device development for acute stroke treatment. FDA approval was based on the multicenter Mechanical Embolus Removal in Cerebral Ischemia (MERCI) trial [17]. 151 patients (mean NIHSS 20) were evaluated within

8 h after onset of symptoms, who were ineligible for standard IAT. Successful recanalization was achieved in 46% of patients with favorable clinical outcome in 27.7%. Mean procedure time was 2.1 h. Clinically significant procedural complications occurred in 7.1% and rate of sICH was 7.8%. The Multi-MERCI trial [18] was a prospective, multicenter, single-arm registry that included 164 patients (mean NIHSS 19) within 8 h after onset of symptoms. In contrast to the MERCI trial, patients with persistent large vessel occlusion after IV tPA were also included in the study, adjunctive IAT using rtPA and the use of other mechanical recanalization techniques and new generation of Merci devices were allowed. Recanalization success was 57.3% using the Merci device alone and 69.5% in conjunction with other treatment modalities. Favorable clinical outcome was achieved

in 36% of patients with clinical significant complications Tacrolimus (FK506) in 5.5% and sICH in 9.8%. Mean time to recanalization was 1.6 h. The introduction of the Merci device was a landmark of mechanical recanalization in acute stroke treatment. Both MERCI trials demonstrated a significantly better clinical outcome in patients with successful recanalization. The most recent developments for mechanical acute stroke treatment are self-expandable, retrievable, stent-like thrombectomy devices. They combine the advantages of intracranial stent placement with immediate flow restoration without the need of permanent device implantation and the advantages of a thrombectomy system with the ability of definitive clot removal.