♦ Preoperative
Operative Planning
- Diagnostic angiography should be performed with specific views that provide excellent visualization of all brachiocephalic vessels and the aneurysm neck and associated branches
Special Equipment
- As for retrograde percutaneous femoral artery puncture
- Five to 7.5 French (F) sheath
- A 5F catheter and guide wire (for diagnostic angiogram)
- A 6 to 7F guiding catheter (7F required for side-by side coiling and balloon remodeling microcatheters. Alternatively, this can be performed via guide catheters in each vertebral artery)
- Over-the-wire microcatheters
- 0.035-inch guide wire and micro–guide wires
- Microballoon catheter for balloon remodeling and/or stents as necessary
- Endovascular detachable coils
- In awake patients, the procedure can be done under local anesthetic with conscious sedation thereby allowing provocative testing.
- In unconscious or patients with impaired level of consciousness, general anesthesia is used for all portions of the procedure.
- Protamine should be readily available if intraoperative rupture occurs.
♦ Intraoperative
Positioning
- Patient is positioned supine.
- A Foley catheter is placed.
- Both inguinal areas are shaved and prepped with iodine solution.
- A sterile drape is placed over the prepped areas.
Treatment
- Femoral artery puncture is performed.
- A diagnostic angiogram is performed with all views necessary to determine aneurysm morphology and its association with the parent artery and its branches.
- A 5 to 7F guide catheter is placed in the appropriate cervical artery.
- An appropriate microcatheter is then selected to gain intracranial access and allow aneurysm embolization. Two types of catheters are available: flow-directed catheters and catheters that advance over a guide wire.
- Flow-directed catheters facilitate superselective catheterization of the parent vessel. They are most suitable for treating mycotic aneurysms. These catheters are also softer than catheters that are advanced over the wire. The lack of wire guidance when advancing flow-directed catheters makes it harder to engage an artery. The small diameter of these catheters precludes the use of coils.
- Catheters that advance over the wire are usually 0.014 and 0.018 inches (inner diameter). Although the authors prefer this type of catheter, its use for the treatment of mycotic aneurysms may be associated with higher rates of aneurysm or vessel perforation. The choice of catheters is based on the operator’s personal preference. There are many types of coils, and their choice also depends on the operator.
- Flow-directed catheters facilitate superselective catheterization of the parent vessel. They are most suitable for treating mycotic aneurysms. These catheters are also softer than catheters that are advanced over the wire. The lack of wire guidance when advancing flow-directed catheters makes it harder to engage an artery. The small diameter of these catheters precludes the use of coils.
- Mycotic aneurysms are usually small, occur at distal locations, have friable walls, and lack a discernible neck. Therefore, the occlusion of the parent vessel is usually required.
- When embolization involves an eloquent region of the brain, amylobarbitol (30 to 50 mg) is injected selectively before the definitive parent vessel is occluded. Positive findings on the test help to predict future deficits. However, negative findings neither preclude nor predict the late occurrence of neurologic deficits. When a clear deficit occurs during provocative testing, cerebral revascularization should be considered. The main disadvantage of provocative testing is that the patient is awake during the procedure, and movement may make the procedure more difficult and may cause parent vessel injury or dissection.
- Embolization material
- The efficacy of N-butyl cyanoacrylate (NBCA) and coils for occluding vessels is probably similar. They also have similar rates of recanalization.
- N-butyl cyanoacrylate embolization is usually faster than coil embolization, requiring less time before the ultimate goal of occlusion is achieved. If an aneurysm ruptures intraoperatively, NBCA facilitates the rapid occlusion of the parent vessel compared with coil detachment. Before NBCA is injected, the catheter is flushed with 5% dextrose to purge the ionizing saline and blood. Potentially, the catheter can adhere to the parent artery from within, making it impossible to retrieve without open surgical excision and predisposing the patient to arterial rupture with overaggressive efforts at removal.
- Coils also can be used to occlude the aneurysm or parent artery, although they take longer to deploy than NBCA, and the catheter must be advanced over the wire.
- Follow-up angiography postembolization should be performed to evaluate both the adequacy of treatment as well as to insure no untended embolization or untoward event occurred.
- The efficacy of N-butyl cyanoacrylate (NBCA) and coils for occluding vessels is probably similar. They also have similar rates of recanalization.
♦ Postoperative
- Patient should be maintained in a neurological intensive care unit overnight to evaluate for acute neurologic change.
- Some centers maintain patients on heparin anticoagulation until postoperative day 1; however, this is controversal.
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