Vein graft replacement of the distal vertebral artery

A reappraisal of saphenous vein grafting

Autologous saphenous vein grafting has been broadly used as a bypass conduit, interposition graft, and patch graft in a variety of operations in cardiac, thoracic, neurovascular, general vascular, vascular access, and urology surgeries, since they are superior to prosthetic veins. Modified saphenous vein grafts (SVG), including spiral and cylindrical grafts, and vein cuffs or patches, are employed in vascular revascularization to satisfy the large size of the receipt vessels or to obtain a better patency. A loop SVG helps flap survival in a muscle flap transfer in plastic and reconstructive surgery. For dialysis or transfusion purposes, a straight or loop arteriovenous fistula created in the forearm or the thigh with an SVG has acceptable patency. The saphenous vein has even been used as a stent cover to minimize the potential complications of standard angioplasty technique. However, the use of saphenous vein grafting is now largely diminished in treating cerebrovascular disorders, superior vena cava syndrome, and visceral revascularization due to the introduction of angioplasty and stenting techniques. The SVG remains the preferable biomaterial in coronary artery bypass, coronary osteoplasty, free flap transfer, and surgical treatment of Peyronie disease. Implications associated with saphenous vein grafting in vascular access surgery for the purpose of dialysis and chemotherapy are considerable. Vascular cuffs and patches have been developed as an important and effective means of enhancing the patency rates of the grafts by linking the synthetic material to the receipt vessel. In addition, saphenous veins can be a cell source for tissue engineering. We review the versatile roles that saphenous vein grafting has played as well as its current status in therapy.

Evolution of cerebral revascularization techniques

✓As a leading cause of death and disability in patients across the world, stroke is a problem that plagues both neurosurgeons and neurologists alike. Whether a result of atherosclerosis, moyamoya disease, or a complication in the treatment of a complex intracranial aneurysm, cerebrovascular occlusion can have devastating effects on patients. For nearly half a century neurosurgeons have searched for safer, more effective ways to increase the amount of blood flow to ischemic brain tissue. From the first extracranial–intracranial bypasses to the recent technological advancements seen with endovascular therapy, cerebral revascularization techniques have been constantly evolving. Over the years cerebral ischemia has gone from a condition that was previously considered surgically untreatable, to a condition with several viable options for prevention and treatment. In this paper the authors discuss the historical evolution of treatment for cerebrovascular occlusive disease.

Cervical venous organization in the transverse foramen

The most widely accepted description of venous anatomy in the transverse foramen involves the presence of one or two veins running along and parallel to the external side of the vertebral artery. For most surgeons, the vertebral artery is surrounded by a rete of veins which is continous with the wide sinusoids which surround the thecal sac (internal vertebral venous plexus). The goal of this study was to ascertain the exact structure of the venous system in the transverse canal by micro dissection and histology. Six spinal segments (C1 to C7) removed from cadavers embalmed using 5% diluted formalin or not and studied with or without injection of colored latex after bilateral catheterization of the internal jugular vein, vertebral vein, common carotid artery, and vertebral artery. An anatomical study was performed by optical microscopy. After fixation and decalcification, tissue specimens were stained using hematoxylin-eosin-safran (HES) and immunocytochemical markers including CD43, CD31, and desmine (specific for vascular endothelium). Findings showed that venous blood in the transverse canal flows through a space formed by the periosteum. There was no evidence of a vein inside the transverse canal. The periosteum spans the space between the transverse processes and gives off fibrous leaflets to the artery thus forming a compartmentalized space lined with vascular endothelium around the artery. The venous system in the transverse canal presents itself as a sinus similar to the intracranial sinus structure.

Cerebral revascularization for aneurysms and tumors

OBJECTIVE

To discuss the indications, techniques, pitfalls, complication avoidance, and management of cerebral revascularization techniques for the treatment of aneurysms and cranial base tumors.

METHODS

The indications for cerebral revascularization procedures included microsurgical occlusion of a parent vessel during the treatment of aneurysms and occlusion of a major vessel during the treatment of basal tumors. The techniques discussed include arterial patch grafting, end-to-end anastomosis, side-to-side anastomosis, arterial interposition grafting, and extracranial-to-intracranial bypass grafting, using radial artery grafts or saphenous vein grafts.

RESULTS

During the 15-year period between 1985 and 2000, the senior author performed 24 radial artery grafts, 105 saphenous vein grafts, and 8 other revascularization procedures, among 50 patients with aneurysms and 83 patients with cranial base tumors. The overall patency rate was 95.6%. Twenty-three patients experienced a cerebral infarction; among those patients, 17 (12.5%) exhibited symptoms but the majority demonstrated considerable recovery during the follow-up period. One hundred one patients recovered to an excellent (Glasgow Outcome Scale score of 5) or good (Glasgow Outcome Scale score of 4) condition. Fifteen patients died as a result of recurrence or progression of tumors during the follow-up period. There were five perioperative deaths. For the last 35 patients, the surgical mortality rate was 0%, with all patients returning to an excellent or good condition.

CONCLUSION

Although highly specialized, these sophisticated cerebral revascularization techniques should be learned and practiced by all neurosurgeons who wish to microsurgically treat intracranial aneurysms or cranial base tumors.

Cerebral revascularization using radial artery grafts for the treatment of complex intracranial aneurysms: techniques and outcomes for 17 patients

OBJECTIVE

The goal of this report is to illustrate the use of radial artery grafts as bypass conduits in the management of complex intracranial aneurysms and to describe a new "pressure distension technique" to eliminate postoperative vasospasm, which was a common problem early in our experience.

METHODS

This study included a series of 17 patients who were surgically treated between 1994 and January 2001 for complex intracranial aneurysms. Five patients were surgically treated without the pressure distension technique; for 12 patients, the technique was used to reduce postoperative vasospasm. Fourteen of the patients had anterior circulation aneurysms, and three had posterior circulation aneurysms. Five of the patients had undergone previous attempts at direct clipping or excision and reconstruction of the aneurysm in question, and embolization had been performed for one patient with a carotid-cavernous fistula. Thirteen patients underwent permanent revascularization combined with proximal occlusion, trapping, or clipping, and four patients underwent temporary revascularization for cerebral protection during anticipated prolonged occlusion of the parent vessel during aneurysm dissection. Surgical techniques are described, with particular reference to vessel collection and bypass techniques.

RESULTS

The outcomes for this group of patients, considering the complexity of the aneurysms and their "inoperability," with respect to direct clipping, were satisfactory. The aneurysms were completely obliterated for all patients, and the grafts were patent for all except one patient on postoperative angiograms. There were two deaths, one attributable to systemic sepsis and the other attributable to cardiac arrest during a transbronchial biopsy. The postoperative Glasgow Outcome Scale scores were either better or the same for all other patients, compared with their preoperative scores. Three of the five patients treated before the institution of the pressure distension technique experienced vasospasm of the graft, with two of those patients requiring angioplasty. For one of those patients, angioplasty led to rupture of the graft. Vasospasm was not observed for any of the 12 patients for whom the pressure distension technique was used. We observed no morbidity related to radial artery collection.

CONCLUSION

Revascularization techniques are occasionally necessary for the surgical treatment of complicated intracranial aneurysms. The merits of the use of the radial artery as a bypass conduit are discussed. Radial artery grafts should be considered as alternatives to saphenous vein and superficial temporal artery grafts. The problem of vasospasm of the artery has been solved with the pressure distention technique.

Venous and arterial bypass grafts for difficult tumors, aneurysms, and occlusive vascular lesions: evolution of surgical treatment and improved graft results

OBJECTIVE: In the treatment of patients with cranial base tumors, unclippable aneurysms, or medically intractable ischemia, it may be necessary to use high-flow bypass grafts. The indications, surgical techniques and complications are discussed. METHODS: During a 10-year period, 99 saphenous vein grafts and 3 radial artery grafts were performed for 101 patients, i.e., 72 with neoplasms, 23 with aneurysms, and 6 with ischemia. Clinical follow-up monitoring of the patients was by direct examination or telephone interview, with a mean follow-up period of 41.2 months (range, 5-147 mo). Radiological follow-up monitoring was by magnetic resonance imaging, magnetic resonance angiography, or three-dimensional computed tomographic angiography, with a mean follow-up period of 32 months (range, 1-120 mo). During the follow-up period, there was one late graft occlusion and one graft stenosis. RESULTS: The use of intraoperative angiography improved the patency rate from 90 to 98% and reduced the incidence of perioperative stroke from 13 to 9.5%. Ninety-two percent of the patients were in excellent or good neurological condition at the time of discharge from the hospital, compared with 95% before surgery. The perioperative mortality rate was 2%. Other complications included three intracranial hematomas, rupture of a vein graft in a patient with Marfan's syndrome, and five tumor resection-related problems. The long-term survival rates for patients who received grafts were excellent for patients with benign tumors, fair to poor for patients with malignant tumors, good for patients with aneurysms, and excellent for patients with ischemia. CONCLUSION: The results of saphenous vein and radial artery grafting have been greatly improved by the use of intraoperative angiography, improvements in surgical techniques, and improved perioperative treatment.

Management of the vertebral artery in excision of extradural tumors of the cervical spine

Extradural tumors of the cervical spine may involve the vertebral artery on one or both sides, posing one of the limiting factors toward the radical resection of such neoplasms. A standard anterior approach may be inadequate for the management of such tumors. An anterolateral approach allows the dissection and mobilization of the vessel, which can then be preserved, resected, or reconstructed with a vein graft. An anterior approach can be supplemented with this for tumor resection and stabilization. This management strategy is described in 10 patients with a variety of tumors.

Extreme lateral transcondylar approach: technical improvements and lessons learned

An extreme lateral transcondylar or extreme lateral transfacetal surgical approach was used to treat 22 patients with complex lesions over a 22-month period. The lesions included basilar invagination with vertebral artery pathology, giant aneurysm or arteriovenous fistula of the vertebral artery, meningioma, chordoma, chondrosarcoma, and paraganglioma. The approach was used alone or in combination with a presigmoid petrosal or subtemporal-infratemporal approach. Refinements of the operative technique, treatment strategies for complex lesions, and the avoidance of complications are discussed. Complications included cerebrospinal fluid leakage, meningitis, pseudomeningocele, hemiparesis or quadriparesis, lower cranial nerve deficits, and vertebral artery injury requiring repair. With treatment, major neurological deficits resolved completely in three patients and partially in two. There was no operative mortality, but four patients died during the follow-up period. For the 18 surviving patients, the mean preoperative and postoperative Karnofsky scores were 81 and 93, respectively. For the four who died, the mean preoperative Karnofsky score was 73 and the mean postoperative score was 63.