Concentric Retriever Device (CRD) in Acute Ischemic Stroke

The primary objective is to assess the safety and efficacy of the Concentric Retriever in
the treatment of thrombotic occlusions originating in the internal carotid, middle cerebral
(M1 and M2 segments), basilar, posterior cerebral or vertebral arteries. A maximum of 50
patients may be enrolled at a single site, University of California, Los Angeles.

Primary endpoints: Achievement of recanalization (TIMI/TICI grade II or III flow)
immediately post procedure without occurrence of major complications will be assessed. Major
complications are defined as vessel perforation, intramural arterial dissection, symptomatic
intra-cranial hemorrhage, and significant embolization in a previously uninvolved arterial
territory.

Secondary endpoints: Assessment of patient's neurological condition and functional state
using the NIHSS, Barthel Index, and Modified Rankin at 30 and 90 days post-procedure. A
composite of major adverse events at 30 and 90 days post-procedure will be reported. Major
adverse events are defined as death and new stroke.

Inclusion Criteria:

1(a) -Patients who present within 8 hours of stroke onset and are not candidates for
treatment with t-PA who have clinical signs consistent with the diagnosis of ischemic
stroke such as impairment of language, motor function, sensation, cognition, and/or gaze,
or vision.

1(b). Patients who have had an acute ischemic stroke treated with intravenous thrombolytic
therapy where vascular imaging (TCD, CTA, MRA, angiography) shows a persistent occlusion
after the end of the infusion treatment.

2. Patients > 18 years of age. 3. NIHSSS > 7 4. Angiogram shows a thrombotic occlusion
originating in the internal carotid, middle cerebral (M1 or M2 segment), basilar,
posterior cerebral, or vertebral arteries.

5. Patient/patient guardian is willing to comply with the protocol requirements and return
to the treatment center for all required clinical evaluations.

Exclusion Criteria:

1. Patient is pregnant (if within child bearing age).

2. Patient has baseline glucose of < 50mg/dL (<50 mg/mM).

3. Patient has excessive arterial tortuosity that precludes the device from reaching the
target area.

4. Patient has known hemorrhagic diathesis, coagulation factor deficiency, or oral
anticoagulant therapy with INR > 2.0.

5. Patient received Heparin within 48 hours with a PTT greater than 2 times the lab
normal.

6. Patient has baseline platelets < 30,000.

7. Patient has history of severe allergy to intra-arterial contrast medium.

8. Patient has severe, sustained hypertension (systolic blood pressure > 185 mm Hg or
diastolic blood pressure > 110 mm Hg).

NOTE: If the blood pressure can be successfully reduced and maintained at the
acceptable level using medication (i.e. Nipride), the patient can be enrolled.

9. CT Scan or MRI reveals significant mass effect with midline shift.

10. Patient's angiogram shows an arterial stenosis (>50%) proximal to the embolus.

11. Patient's anticipated life expectancy is less than 3 months.