Operative Planning

• Preoperative angiography is essential to determine clinical and objective flow failure with hypotensive challenge in the setting of temporary carotid occlusion

Special Equipment

• Micro-instruments and sewing background
  
• Heparinized irrigating solution
  
• Temporary clips

Anesthetic Issues

• Anticonvulsants
  
• Perioperative antibiotic coverage
  
• Mild hypothermia (33˚ C)
  
• Barbiturates for cerebroprotection
  
• Does not necessarily require electroencephalogram for monitoring

Positioning

• Mayfield head holder placed in anteroposterior position
  
• Patient’s head turned so that temporal squamosa is parallel to floor
  
• The hair overlying the region of the temporal squamosa is shaved (center over the STA pulse)
  
• Shoulder roll under ipsilateral shoulder
  
• The contralateral medial calf is prepped
  
• Pneumatic compression device is placed on the nonoperative calf

Sterile Scrub and Prep

• Same as for general craniotomy

Mark Incisions

• Skin incision marked ~12 cm long along the palpable STA pulse
  
• A point 6.5 cm superior to the external auditory meatus is marked (posterior sylvian fissure) and an incision is extended along the path of the sylvian fissure

Vein-Graft Harvest

• The skin is incised 1 cm anterior and rostral to medial malleolus
  
• The saphenous vein is identified and a plane just beneath the adventitia of the vessel is developed
  
• The incision is extended until ~ 10 cm of vein is exposed
  
• One or two side branches are identified that will be used for graft irrigation; they are ligated with 4–0 silk sutures and transected, leaving a 1-cm stump for irrigation
  
• The surface of the vein and its direction of flow are marked so as to avoid rotation or malpositioning of the graft
  
• The distal portion of the vein is gently dissected, leaving the saphenous nerve intact; the vessel is excised when all other side branches have been tied or cauterized
  
• The graft is gently irrigated with heparinized saline and placed in a heparinized saline bath
  
• Longer bypasses (up to 20 cm) can be harvested in similar fashion (up to the level of the knee)
  
• Hemostasis obtained at the incision site and irrigated with antibiotic solution
  
• The wound is closed with 3–0 Vicryl interrupted subcutaneous sutures and staples
  
• Ace wrap can be applied to the leg

Craniotomy: Incision and Exposure

Middle Cerebral Artery Branch Preparation

• In general, the angular branch of the MCA is an adequate recipient vessel; if not, enter the sylvian fissure to identify a large branch
  
• If necessary, a division of the MCA can be used but may carry a higher risk of ischemia or infarct secondary to the occlusion time necessary for anastomosis
  
• The recipient branch is isolated by carefully dissecting around it with microscissors
  
• Attempt to preserve as many side branches as possible, though some (up to three) can be sacrificed with bipolar cautery at low current strength
  
• Larger side branches can be temporarily occluded with 9–0 nylon with a bowtie knot or microclip to allow for removal at the conclusion of the procedure
  
• A yellow rubber tying platform is placed beneath the recipient vessel

Vein-Graft Preparation

• The orientation of the graft is reversed; the graft is temporarily placed into the craniotomy site to “test fit” the projected route of the graft with its proximal end near the MCA
  
• A bevel is made at the proximal end of the vessel with two distinct cuts at a ~45-degree angle; the bevel should be approximately twice the diameter of the recipient vessel; the tip of the bevel should not come to a point so as to hold the stitch better and to prevent luminal narrowing when the anastomosis is performed
  
• The intracranial anastomosis is then performed; 8–0 Prolene suture (Ethicon) can be optimal in this setting

Intracranial Anastomosis

Proximal Anastomosis

• The graft is tunneled subcutaneously to the proximal anastomosis site; avoid twisting or kinking of the graft
  
• The graft is trimmed to an appropriate length that will not result in excessive tension or redundant graft tissue
  
• An end-to-side anastomosis is performed with 6–0 or 8–0 monofilament suture in a fashion similar to that described previously
  
• Before the final suture, the temporary clips are sequentially removed from the parent artery to allow blood to flush through the anastomosis site
  
• The clips are replaced and the site irrigated with heparinized saline, thus flushing the graft free of air
  
• The final stitch is placed; a temporary clip is placed on the graft distal to the stump used to flush the graft
  
• The temporary clips are removed from the parent vessel
  
• The graft is assessed for flow, confirming that all air has been removed from the graft; the stump is tied with a 4–0 suture
  
• The temporary clip is removed from the graft and graft patency assessed
  
• Avitene is placed at the suture lines with gentle pressure for 5 minutes
  
• If bleeding continues, further sutures may be required
  
• The operative fields are copiously irrigated

Closure

• The dura is reapproximated with 4–0 silk sutures; avoid compression of the anastomosis
  
• Gelfoam is placed over the site
  
• The bone flap is replaced; make certain that the graft is in the burr hole
  
• The wound is closed in layers with 3–0 Vicryl; take care not to compress the graft
  
• The skin is reapproximated with interrupted 3–0 nylon sutures
  
• The proximal anastomosis site is closed in the appropriate fashion
  
• A dry sterile dressing is placed over the incisions
  
• The graft pulse is palpated to ensure patency