The study aims to evaluate the safety and probable benefit of a medical device to treat wide-neck ruptured brain aneurysms.

Patients with ruptured brain aneurysms will be treated with the Nautilus, then will be followed up for one year.

Inclusion Criteria:

1. Subject is ≥18 years old
2. Subject who presents with an angiographically confirmed, wide neck intracranial saccular, acutely ruptured aneurysm. Wide neck is defined as 4-7mm.
3. Aneurysm dome ≥5 mm.
4. Subject is neurologically stable with a Hunt & Hess score of I, II, or III.
5. In the opinion of the treating physician, placement of the Nautilus is technically feasible and clinically reasonable.
6. The subject or authorized representative is able to provide informed consent and has signed the IRB-approved informed consent form.
7. Subject must be able to comply with all aspects of the screening, evaluation, treatment, and the post-procedure follow-up schedule.

Exclusion Criteria:

1. Subject with any neurological deficit occurred within the last 180 days; defined as previous non-aneurysmal subarachnoid hemorrhage or any other non-aneurysmal intracranial hemorrhage, stroke, transient ischemic attacks (TIA), concussion, head trauma, cranial surgery, radiation therapy to the head.

2. Premorbid mRS score ≥3.

3. Subject has another aneurysm which, in the Investigator's opinion, will require treatment within the follow-up period (1 year).

4. Women of child-bearing potential age (18-55) who cannot provide a negative pregnancy test.

5. Subject with other serious comorbidities that carry a high risk of neurologic events such as:

   • Significant acute or chronic cardiovascular disease such as myocardial infarction within the past 180 days
   • Uncorrectable coagulation abnormality
   • Uncontrolled diabetes mellitus with target organ injury
   • Organ failure of kidney, liver, heart or lungs
   • Arteriovenous malformation or arteriovenous fistula, Moyamoya disease, or any other vasoconstriction
   • Premorbid intracranial tumor or hematoma

6. Severe or unstable conditions or diseases (e.g., non-significant neurological deficit, cancer, hematologic or coronary disease) or chronic conditions that in the opinion of the investigator may increase the risk associated with study participation for study device administration or may interfere with the interpretation of study results.

7. Extreme vessel stenosis or tortuosity or other vascular anomalies that would prevent delivery of the device to the target.

8. Comorbidities that may preclude obtaining follow-up DSA.

9. Known allergy to Nickel and/or Heparin that cannot be medically treated.

10. Subject is currently participating in another interventional clinical study.

11. Subject with a relative contraindication to angiography (i.e., allergy to contrast media, coagulopathy, etc.)