2 The procedure
2.1.1 Aneurysms and other abnormalities of arteries supplying the brain may be suitable for treatment by open surgery or endovascular techniques, such as insertion of coils or stents. In some cases, arterial bypass of an abnormality may be necessary. This is achieved either by direct anastomosis between branches of the external carotid and internal carotid arteries or by an interposition saphenous vein or radial artery graft. In both techniques there is a risk of stroke as the cerebral blood supply is temporarily occluded while the anastomosis to the intracranial artery is performed.
2.2.1 The laser-assisted non-occlusive anastomosis technique aims to achieve cerebral arterial bypass without the need for temporary arterial occlusion, thus maintaining cerebral blood flow throughout the procedure.
2.2.2 The procedure is performed under general anaesthesia. The distal (cerebral) anastomosis site is prepared by stitching a platinum ring onto the wall of the recipient vessel. The bypass graft is sutured end-to-side to the recipient vessel outside the ring. A combined laser–vacuum suction catheter is introduced through the bypass graft into the platinum ring on the wall of the recipient vessel. Using vacuum suction and laser pulses, a disc-shaped area is resected in the wall of the recipient vessel. This punched-out disc is withdrawn while still attached to the vacuum catheter, completing the anastomosis without interrupting cerebral blood flow. The graft is then temporarily clipped to prevent backflow while the resected wall is closed (in direct extracranial/ intracranial bypass) or the proximal anastomosis is formed (in indirect interposition extracranial/intracranial bypass). When interposition grafts are used, the proximal anastomosis is performed using a standard end-to-end or end-to-side anastomosis.
Sections 2.3 and 2.4 describe efficacy and safety outcomes which were available in the published literature and which the Committee considered as part of the evidence about this procedure. For more details, refer to the Sources of evidence.
2.3.1 In a case series of 77 patients with intracranial aneurysms undergoing bypass using laser-assisted cerebral vascular anastomosis without temporary arterial occlusion, a patent high-flow bypass was successfully created in 97% (75/77) of cases. A patent anastomosis was not achieved in 3% (2/77) of cases because the excised section of the targeted artery wall did not attach to the laser tip on withdrawal. A second procedure was required in 8 patients (10%), usually because of postoperative graft thrombosis.
2.3.2 In a second case series of 15 patients with carotid artery occlusion and recurrent ischaemic symptoms, transcranial Doppler ultrasound of 11 patients who survived to 6 months showed that a patent bypass was maintained in 91% (10/11) of them.
2.3.3 In two case series of 77 and 34 patients, 68% (52/77) and 79% (27/34) of patients were independent (using the modified Rankin scale) at 2–4-month and 3.3-year follow-up, respectively. In the first study, functional health improved in 14% (11/77) of patients, was unchanged in 65% (50/77) and had decreased in 21% (16/77) at 2–4-month follow-up. In the second study, Rankin score (a measure of functional capacity) had improved in 71% (24/34) of patients at discharge and 74% (25/34) at 3.3-year follow-up. Of the 27 patients who had pre-existing cranial nerve compression in the second study, 30% (10/27) resolved at the same follow-up.
2.3.4 The Specialist Advisers considered key efficacy outcomes to be graft patency (including angiographic assessment) without further stenosis and lack of haemorrhage during the procedure.
2.4.1 In four studies, postoperative mortality (up to 30-day follow-up) following laser-assisted cerebral vascular anastomosis without temporary arterial occlusion was reported to be 7% (1/15), 6% (2/34), 4% (3/77) and 0% (0/1), respectively. The indication for the procedure varied between studies.
2.4.2 The case series of 77 patients with intracranial artery aneurysms in whom the procedure was used reported persistent deficit caused by ischaemia in 21% (16/77), by haemorrhage in 5% (4/77) and by other intracranial events in 3% (2/77) of patients. Procedure-related complications resulting in a Rankin score of 3–5 occurred in 9% (7/77) of patients.
2.4.3 The case series of 15 patients with carotid artery occlusion reported that ischaemic stroke occurred in 20% (3/15) of patients and dysphasia with right-sided weakness occurred in 13% (2/15).
2.4.4 The Specialist Advisers considered the theoretical adverse events of the procedure to include leakage of the anastomosis and laser damage to the bypass vessel wall leading to late stenosis.