Saphenous vein bypass grafts for giant aneurysms and intracranial occlusive disease

Transcription

1 J Neurosurg 65: , 1986 Saphenous vein bypass grafts for giant aneurysms and intracranial occlusive disease THORALF M. SUNDT, JR., M.D., DAVID G. PIEPGRAS, M.D., W. RICHARD MARSH, M.D., AND NICOLEE C. FODE, R.N. Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota v" The authors report their experience with the use of saphenous vein bypass grafts for treating advanced occlusive disease in the posterior circulation (77 patients, all of whom had failed medical management and showed severe ischemic symptoms), deteriorating patients with giant aneurysms of the posterior circulation (nine patients), progressive ischemia in the anterior circulation (26 patients, none of whom had a normal examination), and giant aneurysms in the anterior circulation (20 patients, all of whom presented with mass effect or subarachnoid hemorrhage). Graft patency in the first 65 cases treated was 74%. However, after significant technical changes of vein-graft preparation and construction of the proximal anastomosis, pateney in the following 67 cases was 94%. Excellent or good results (including relief of deficits existing prior to surgery) were achieved in 71% of patients with advanced occlusive disease in the posterior circulation, 44% of those with giant aneurysms of the posterior circulation, 58% of those with ischemia of the anterior circulation, and 80% of those with giant aneurysms of the anterior circulation. Mean graft blood flow at surgery in the series was 100 ml/min for posterior circulation grafts and 110 ml/min for anterior circulation grafts. Experience to date indicates that this is a useful operation, and is particularly applicable to patients who are neurologically unstable from advanced intracranial occlusive disease in the posterior circulation or with giant aneurysms in the anterior circulation. The risk of hyperperfusion breakthrough with intracerebral hematoma restricts the technique in patients with progressing ischemic symptoms in the anterior circulation, and the intolerance of patients with fusiform aneurysms in the posterior circulation to the iatrogenic vertebrobasilar occlusion limits the applicability of this approach to otherwise inoperable lesions in that system. KEY WORDS " cerebral aneurysm 9 ischemia 9 extracranial-intracranial bypass 9 vein graft 9 cerebrovascular disease W E have previously reported our initial experience with the use of saphenous vein bypass grafts between the external carotid artery (ECA) and the proximal posterior cerebral artery (PCA) for giant aneurysms and advanced occlusive disease in the posterior circulation. 9 These procedures were first undertaken to provide an immediate large volume of flow to patients with impending brain-stem infarction from stenoses or occlusions of the basilar artery. Eno couraging results led us to extend the use of the procedure to selected cases with advanced occlusive disease in the anterior circulation and to patients with giant aneurysms in both the anterior and posterior circulation. Our experience with this operation now seems sufficient and the follow-up period is long enough for us to report our results and complications with saphenous vein bypass grafts for giant aneurysms and intracranial occlusive disease. The indications and rationale for this operation in patients with occlusive disease and aneurysms in the posterior circulation have been considered in detail previously 9 and will not be reviewed here. However, we will consider pitfalls in the operative procedure that have led to complications and illustrate our current use of the operation with typical cases of aneurysms and occlusive disease in the anterior and posterior circulation. Clinical Material and Methods From November l, 1979, through December 31, 1985, 132 saphenous vein bypass grafts were placed in patients with giant aneurysms or advanced occlusive disease in the anterior or posterior circulation. The case records were abstracted and the data recorded on a standardized form for keypunching. The results were analyzed by standard statistical methods. J. Neurosurg. / Volume 65 / October,

2 T. M. Sundt, Jr., et al. After dismissal from the hospital, patients were scheduled for follow-up examinations. Individuals who were unable to return to our facility because of financial or logistical considerations were contacted by telephone or letter. Information regarding neurological function, work capacity, and clinical symptoms was entered into the case record. Neurological outcome, including deficits prior to surgery, was divided into four categories as follows: Excellent: patients with essentially normal neurological function Good: patients with a slight disability who were nevertheless productive and essentially capable of living a normal life with only minimal limitations Poor: patients with moderate or severe disability who required family or nursing assistance Dead. Surgical Technique The surgical technique for placement of a saphenous vein bypass graft between the ECA and the proximal PCA has been described previously and accordingly we will not dwell upon the details of the approach here. 9 However, through experience, we have found a number of potential pitfalls in the operation with possible sources for complications which we present here. Preparation of the Vein Correct preparation of the vein is one of the most important aspects of the operative procedure. The cause for many of our early graft failures was related to lack of attention to detail in the preparation of the vein. A segment of the long saphenous vein is usually harvested from the leg. However, if the patient has a relatively small saphenous vein, it is necessary to extend the incision proximally and select a segment of vein from the thigh. On two occasions it has been necessary to use segments of saphenous veins from both lower extremities and to anastomose these end-to-end in order to obtain a sufficient length of vein with an adequate caliber. When distended, the vein should be between 6 and 9 mm in diameter. A vein smaller than this will tend to occlude. Veins greater than 1 cm in diameter are too large as they create a disproportion at the anastomosis site between the calibers of the donor graft and the recipient artery. The vein is harvested from the leg as shown in Fig. I. Large branches of the vein are doubly ligated with 3-0 silk suture and smaller branches are closed with 5-0 Prolene suture. On occasion, in order to prevent the vein kinking at the point where a large tributary is ligated, instead of ligating the major branch with a single 3-0 silk suture it is better to close the junction point with a running 5-0 Prolene suture, as this creates less distortion. Before removing the vein, a 5-0 Prolene suture is placed in the adventitia of the vessel as an orientation line. We refer to this as a "Garrett line," named after the vascular surgeon from whom this tech- FIG. 1. Technique of harvesting the vein graft. A: The great saphenous vein is harvested from the leg or thigh. There is considerable variability from patient to patient in the size of this vessel and in the number of branches. B: Small branches are ligated with 5-0 Prolene stick-ties and large branches with 3-0 silk stick-ties. Sometimes it is preferable to close large tributary vessels with a running 5-0 suture rather than ligate the vessel with a larger suture, as the simple ligation with a tie sometimes distorts the lumen of the vein. The vein should be left in situ after the tributaries have been ligated and harvested only after exposure of the intracranial recipient vessel and the cervical carotid arteries. The Garrett orientation line should be placed in the adventitia of the vein before it is harvested: there is frequently 360* to 720 ~ rotation of the vein with distention after it is harvested, and the proper orientation cannot be determined. C: The vein is distended with the Shiley distention kit to 200 mm Hg. The vein is worked between the index finger and thumb under cold heparinized saline solution until the vasospasm is overcome. nique was learned. This is an extraordinarily important step in the procedure as the vein tends to rotate with distention after it is harvested from the leg and, unless its proper orientation has been identified in situ, any rotation of the vein cannot be corrected thereafter and will predispose to twisting and kinking. It is preferable to place the Garrett line before mobilizing and ligating the branches of the vein. The vein is then distended with cold heparinized saline (1000 U heparin/100 cc saline) utilizing the Shiley balloon-distention system. This system has a balloon that inflates at 200 mm Hg and thus prevents overdistention and fracture of the vein wall. The vein is gently worked between the index finger and thumb under saline irrigation until the spasm is overcome. An early cause for graft occlusion in this series was thought to be related to overdistention of the vein. Cervical Exposure of Carotid Arteries The carotid arteries are exposed as for an endarterectomy; however, the dissection is usually carried 440 J. Neurosurg. / Volume 65/October, 1986

3 Vein graft bypass for intracranial vascular disease FIG. 2. Exposure of the posterior circulation. The posterior cerebral artery is exposed through a subtemporal approach. The temporal muscle is turned with the scalp flap. The craniotomy should extend to the floor of the middle fossa. higher and the incision extended superiorly and anterior to the tragus of the ear. The parotid gland is mobilized anteriorly and superiorly to give good exposure to the distal external and/or internal carotid arteries. In some patients with a high bifurcation it is necessary to identify the seventh nerve near its point of exit from the stylomastoid foramen and trace it somewhat distally. Details of this technique have been described previously. 9 Intracranial Exposure Posterior Circulation. The subtemporal approach (Fig. 2) is routinely employed for exposure of the PCA. The temporal muscle is turned with the scalp flap and the craniotomy is carded as low as the floor of the middle fossa. We always use cerebrospinal fluid (CSF) drainage and occasionally administer mannitol as well. Mannitol has a theoretical advantage of improving the brain's tolerance to ischemia but we have concluded that it also is associated with increased problems of bleeding and an increased incidence of temporal lobe hematomas. In most instances, adequate room can be achieved with CSF drainage alone. The Ya~argil selfretaining retractor is essential (one blade is sufficient). The inferior aspect of the temporal lobe is covered with one large square of Surgicel and Gelfoam before the cottonoids are placed for the brain retractor. The Surgicel is left in place and has prevented small bleeding points from developing when the cottonoid is removed from the wound. This is important, as the 4000 to 5000 U of heparin given prior to PCA occlusion is not reversed. Just before temporary occlusion of the vessel, the patient is also given 250 mg of pentobarbital. The PCA is dissected free from the arachnoid where it courses around the peduncle. The P1 segment of the PCA and the third nerve are not exposed. The anterior half of the P2 segment is selected for the anastomosis. It is usually about 25 mm long and is essentially free of perforating vessels. The long and short circumflex thalamoperforating arteries arise proximal to the point of temporary occlusion. In some cases the anterior temporal artery arises in the field of occlusion but it is usually at the posterior limit of the area. The posterior choroidal and posterior temporal branches of the PCA arise well distal to the point of temporary occlusion. The hippocampal, peduncular perforating, and medial posterior choroidal arteries seem to arise proximal to the point of occlusion. At the point of anastomosis, the PCA is usually about 3 to 3.5 mm in diameter, which compares favorably with the diameter measured in fixed specimens by Zeal and Rhoton. ~~ Anterior Circulation. The middle cerebral artery (MCA) is exposed through the classic pterional approach. The arachnoid is opened and the frontal lobe retracted slightly superiorly. A second malleable retractor secured on a self-retaining system is occasionally used to gently retain the superior aspect of the temporal lobe. The point selected for the anastomosis is on one of the two major limbs of the MCA, usually the superior limb as in most instances it is slightly larger than the inferior limb and is more readily accessible for the anastomosis. Preparing a Tunnel for Graft A No. 20 French argyle trocar catheter is inserted into the temporal muscle and passed over the zygoma through the deep layer of subcutaneous tissue anterior to the tragus of the ear, where it is then directed deep to the parotid gland to exit in the neck at the upper end of the cervical incision. 7 Care must be taken not to injure the superficial temporal artery in this maneuver from the sharp trocar of the catheter. For this reason, we frequently use a blunt heavy guide similar to that employed for shunt procedures. The distal end of the plastic sleeve is now opened by rotating the trocar over a No. 20 blade knife. The excision of this distal end of the catheter exposes the trocar, to which is now attached a 2-0 silk suture. The trocar is then withdrawn through the sleeve bringing with it the 2-0 silk suture. Vein distention is maintained throughout using the Shiley catheter balloon system and heparinized saline, with an aneurysm clip at the most distal end of the vein. It is important to keep the vein moist during this portion of the procedure. The vein is then straightened by reference to the Garrett line, and the distal end of the vein graft is attached to the 2-0 silk suture and brought through the argyle catheter while vein distention is maintained. The argyle sleeve is then withdrawn over the vein. In this manner, the vein graft can be accurately placed without kinking, rotation, or injury. The path of a completed graft is illustrated in Fig. 3. J. Neurosurg. / Volume 65 /October,

4 T. M. Sundt, Jr., et al FIG. 3. The path of a completed vein bypass graft. The graft ascends deep to the parotid gland to enter a deep subcutaneous plane anterior to the tragus of the ear. It then curves over the zygoma and through the temporal muscle to cross the floor of the middle fossa to the posterior cerebral artery at the margin of the tentorium. ECA = external carotid artery; CCA = common carotid artery. Distal Anastomoses Posterior Circulation. The distended vein is oriented in such a fashion that there is no kinking at its point of exit through the temporal muscle to the site of the anastomosis. The correct direction or orientation of the vein can be further documented at this point by application of a temporary Sugita clip. This allows the surgeon to be quite precise about the direction of the bevel for the distal anastomosis. An additional length of vein is then brought through the wound and the vein is beveled. This additional mobilization is necessary in order to prevent the vein from compromising the surgical field. It can be packed away with a cotton ball to permit adequate visualization during the anastomosis construction. The patient now receives the heparin and 250 mg of pentobarbital. When both medications have circulated, the proximal and distal ends of the PCA are temporarily occluded with angled temporary Sugita clips (Fig. 4). The PCA is then opened for a distance of approximately 8 to 10 mm with a microscissor or tip of a broken razor blade secured in a microholde 9. The base of the beveled vein is then affixed to the distal point of the incision in the PCA using an interrupted 8-0 monofilament nylon suture. This suture should be cut to a length of approximately 4 cm before the anastomosis is made, as a longer suture than this is simply cumbersome and unnecessary. With this suture, two or three additional running stitches are then placed on the medial side of the arteriotomy. Thereafter, the tip of the beveled vein is sewn to the proximal end of the arteriotomy in the PCA with a second interrupted 8-0 monofilament nylon suture. The medial side of the anastomosis is now closed FIG. 4. Construction of the angled end-to-side intracranial anastomosis using an 8-0 monofilament nylon suture. A: The posterior cerebral artery is opened with a broken razor blade after the vessel is occluded with soft temporary clips. B: The vein graft is spatulated and the apices affixed to the ends of the arteriotomy with two sutures cut to a length of 2.5 cm. C: The two sutures are now run from the two ends on the medial wall of the arteriotomy and tied together near the midpoint. D: The self-retaining retractor is then repositioned over the vein graft placing slight tension on the graft and opening the lateral aspect of the arteriotomy. E: Lastly, the lateral walls are closed with running sutures. using these two sutures as running stitches which are tied at the center point of the arteriotomy (Fig. 4). The Ya~argil self-retaining retractor is now released and the vein is brought under the blade of the retractor so as to apply slight tension on the vein. Two additional sutures are now placed as running stitches from the proximal and distal ends of the arteriotomy, respectively, to close the lateral wall of the arteriotomy, Flow is now restored and bleeding points are identified. Not uncommonly, it is necessary to place one or two additional interrupted sutures in order to arrest bleeding. This is particularly true if there is a great disproportion in thickness between the vein and the artery. The vein is now occluded as close to the anastomosis as possible and attention is focused on the neck. Anterior Circulation. The anastomosis to the M2 segment of the MCA is performed in a fashion similar to that described for the posterior circulation. Four sutures are used for four separate running stitches and the apices are anchored as described above. Not infrequently, the two blades of the Ya~argil self-retaining retractor employed in this technique can be used to place temporary tension on the vein graft and facilitate this anastomosis. The exposure and anastomosis is usually easier technically in the anterior than in the posterior circulation, but the artery is smaller. 442 J. Neurosurg. / Volume 65 / October, 1986

5 Vein graft bypass for intracranial vascular disease FIG. 5. End-to-end anastomosis between a vein graft and the stump of the external carotid artery (ECA). The vein graft and ECA are both prepared in a fish-mouthed fashion (A) and then the anastomosis is completed with 12 to 14 interrupted 5-0 or 6-0 Prolene sutures (B). This is currently our most common type of construction for the proximal anastomosis. ICA = internal carotid artery; CCA = common carotid artery. Proximal Anastomoses There is a tendency to underestimate the technical difficulty of proximal anastomoses. It is extraordinarily important that a strong pulse be present in the vein graft after flow is restored, similar to that palpable in the carotid artery; if this is not achieved, the graft must be taken down and the anastomosis redone. Blood flow throught the graft (determined by an electromagnetic flowmeter) is largely related to the distal runoff, whereas the quality of the pulse is related to the vein and to the construction of the proximal anastomosis. Three variations in the proximal anastomosis have been used, and are described as follows. End-to-End ECA Anastomosis. We have preferred to use end-to-end anastomosis of the vein graft to the ECA stump. This technique is routinely used whenever the ECA has an adequate caliber and length. Fortunately, this proves to be the case in most instances. The anastomosis is constructed with 14 to 16 interrupted 6-0 Prolene sutures with both the vein and the artery being prepared in a fish-mouthed fashion (Fig. 5). In cases in which the vessels are smaller than average, the site of the anastomosis is enlarged with a vein roofpatch graft (Fig. 6). End-to-End ICA Anastomosis. End-to-end anastomosis of the vein graft to the internal carotid artery (ICA) is used for bypassing giant ICA aneurysms (Fig. 7). The ICA is divided just distal to its bulb at a point where it matches in caliber the distended vein graft. The anastomosis is thereafter constructed as described for the ECA. End-to-Side Common Carotid Artery Anastomosis. Not infrequently, the ECA is of such poor quality or so heavily involved with atherosclerosis that it is necessary to place the vein graft anastomosis end-toside to the common carotid artery. This anastomosis can be placed at the origin of the ECA or more inferiorly. In several cases, it has been necessary to complete FIG. 6. Enlargement of a proximal anastomosis with a roof-patch graft (steps A through D). This technique is used in cases where the external carotid artery (ECA) or the saphenous vein are smaller than average. If necessary, an anastomosis should be reopened acutely on the operating table for patch-grafting in cases in which the graft pulse appears to be inadequate. Placement of a roof-patch graft in these instances has usually resulted in a very significant improvement in the quality of the pulse and consequently in the long-term patency of the graft. ICA = internal carotid artery; CCA = common carotid artery. FIG. 7. Proximal anastomosis between a saphenous vein and the stump of the internal carotid artery (ICA). This technique is illustrated in a patient with a giant aneurysm undergoing ICA ligation with a simultaneous saphenous vein bypass graft. The bulb of the ICA is preserved for the anastomosis. The vein graft and ICA are both prepared in a fishmouthed fashion and then sewn end-to-end with 12 to 14 interrupted 5-0 or 6-0 sutures. ECA = external carotid artery; CCA = common carotid artery. J. Neurosurg. / Volume 65/October,

6 T. M. Sundt, Jr., et al. FIG. 8. Steps A, B, and C are followed to perform an endarterectomy in the common (CCA), internal (ICA), and external (ECA) carotid arteries in cases in which there is significant stenosis of the ECA. In such cases, the ECA cannot be reconstructed without also involving the CCA and ICA. A shunt is routinely employed in these cases as it is not possible to monitor these patients with cerebral blood flow measurements and electroencephalograms. Following endarterectomy, the ECA is usually divided just distal to its origin and the saphenous vein graft is sewn to the stump with interrupted sutures. Both the saphenous vein and the margin of the ECA are spatulated and then the site of the anastomosis is enlarged with a saphenous vein roof-patch as illustrated in Fig. 6. a standard endarterectomy of the common carotid artery and ICA in order to free the ECA from atherosclerosis. In these cases, experience has taught us that it is wise to patch-graft the site of the anastomosis in order to create a bulb at the origin of the vein graft (Fig. 8). Subdural-Atrial Shunt We have routinely employed subdural-atrial shunts in posterior circulation bypass procedures because we have found that a large percentage of these patients develop subdural hygromas if a shunt is not placed. This does not occur as frequently in bypass procedures involving the anterior circulation. We conclude that it is related to the diverted patterns of CSF flow around the base of the brain because of the pulsating graft in this major cistern. Clinical Material The case material can be divided into four disease categories, each of which is described here according to FIG. 9. Postoperative angiogram in a typical case of occlusive disease of the posterior circulation demonstrating a double-barreled saphenous vein bypass graft with one limb (small arrow) anastomosed to a branch of the middle cerebral artery. The main trunk of the vein is anastomosed end-to-side to the posterior cerebral artery (large arrow). There is retrograde flow in the basilar artery to the point of the anterior inferior cerebellar artery, identified by arrowhead. the patients' symptoms, neurological examination, and vascular pathology. Occlusive Disease in the Posterior Circulation Seventy-seven of the 132 patients in this series had occlusive disease in the posterior circulation. A typical postoperative angiogram is shown in Fig. 9. This 66- year-old man underwent a posterior-circulation bypass procedure because of orthostatically induced episodes of cerebral ischemia. His symptoms included lightheadedness, dysarthria, diaphoresis, double vision, rightsided weakness, and circumoral dysesthesias. These attacks would persist for over 1 hour and were occurring on a daily basis. Following the patient's admission to the hospital, the events continued while he was receiving heparin. During this time, it was observed that he was essentially asymptomatic when supine but had prompt onset of symptoms when assuming the upright position. He had also sustained episodes of right hemispheric ischemia attributable to a right MCA occlusion. Symptoms. Thirty-seven patients were operated on because of multiple transient ischemic attacks (TIA's), which represented the most common indication for 444 J. Neurosurg. / Volume 65/October, 1986

7 Vein graft bypass for intracranial vascular disease FIG. 10. Radiographic findings in a 66-year-old man who underwent surgery because of headaches, progressing ataxia, a left hemiparesis, and progressive loss of function of the fifth to eighth cranial nerves. Left: Preoperative computerized tomography scan showing a very large mass in the left cerebellopontine angle. Center: Preoperative angiogram confirming the presence of a giant aneurysm which was largely thrombosed. The patient underwent placement of a saphenous vein bypass graft between the right external carotid artery and the proximal right posterior cerebral artery, combined with a trapping procedure of the aneurysm. It was hoped that the aneurysm had occluded the origin of the pontine perforating vessels and that the patient would therefore tolerate basilar artery occlusion if provided with an adequate distal flow. Right: Postoperative angiogram demonstrating good flow through the graft. However, the patient developed typical signs and symptoms of basilar artery occlusion following surgery. surgery in this group. These TIA's could not be controlled by anticoagulant or antiplatelet agents preoperatively and were usually "crescendo" in character. Other indications for surgery included: a mild stroke with superimposed TIA's (four cases); orthostatic symptoms of diffuse posterior-circulation ischemia including visual complaints, memory dysfunction, ataxia, and alterations in level of consciousness (31 cases); and progressing stroke (five cases). Frequently, patients had more than one complex of symptoms (for example, although TIA's were the indication for surgery in 37 cases, 54 patients had TIA's). Examination. The preoperative neurological examination was normal in seven cases. Two patients had a mild fixed brain-stem deficit, 10 had mild hemiparesis, 21 had a combination of brain-stem findings such as dysarthria and dysphagia with hemiparesis, peripheral ataxia, or visual field deficit, and 11 patients had primarily severe truncal or limb ataxia. Nineteen patients had a normal examination in the supine position, but developed visual complaints or mixed brainstem deficits in the upright position (these patients were confined to bed). In five patients, the chief findings were visual field deficits. In two patients, major problems with memory and cerebration were the primary findings. Vascular Pathology. Thirty-four patients had a high-grade focal stenosis of the basilar artery, four had tandem focal lesions, six had a focal occlusion of the basilar artery, and one had a segmental basilar artery occlusion. There were 24 cases of unilateral vertebral artery occlusion associated with a contralateral intracra- nial vertebral artery stenosis, and eight cases of bilateral intracranial vertebral artery occlusions. Giant Aneurysms in the Posterior Circulation Nine patients had giant aneurysms in the posterior circulation, all of whom underwent basilar or vertebral artery ligation combined with a saphenous vein bypass graft. Cerebrovascular findings typical for this group are illustrated in Fig. 10. Symptoms. Two of the nine patients had symptoms of an acute subarachnoid hemorrhage. The other seven patients had mass-effect symptoms related to the size of the aneurysm, primarily associated with brain-stem compression; these included dysarthria, dysphagia, hemiparesis, peripheral ataxia, and extraocular muscle findings. Four patients in this group had fusiform aneurysms of the basilar artery and, according to their history, also had sustained embolic events. Examination. The patients with an acute subarachnoid hemorrhage had signs and symptoms related to the bleed but did not have a major fixed deficit. One patient had a normal examination. All other patients had signs of brain-stem compression, and examination verified the symptoms outlined above. Vascular Pathology. Five aneurysms were located at the caput of the basilar artery, and four fusiform aneurysms involved the vertebral arteries and the basilar trunk. Occlusive Disease in the Anterior Circulation Twenty-six patients had ischemia in the anterior J. Neurosurg. / Volume 65/October,

8 T. M. Sundt, Jr., et al FIG. 11. Angiograms in a 60-year-old man who presented with a 3-month history of progressive deterioration in mental function, loss of vision in the left eye, episodes of dysequilibrium, and progressive loss of function in the left hand. On examination, he had a mild left hemiparesis. Left: Preoperative angiogram showing diffuse atherosclerosis not only involving the carotid artery at its bifurcation but extending distally to the point where the vessel enters the base of the skull. There is also separate involvement of the artery in the parasiphon area. The right internal carotid artery is occluded. Right: Angiogram after the placement of a saphenous vein bypass graft from the right subclavian artery to the right middle cerebral artery. The vein graft now supplies both anterior cerebral arteries and has a potential for supplying the left middle cerebral artery group. This patient has done well postoperatively. circulation. Typical angiograms for this group are illustrated in Fig. 1 I. Symptoms. Seven patients had a slow stroke (a slowly evolving neurological deficit greater than 72 hours in duration), six patients had a progressing stroke, six had orthostatic symptoms of diffuse hemispheric ischemia, four had a completed stroke with superimposed TIA's, and three had "crescendo" TIA's. Examination. None of the patients in this group had a normal neurological examination. Nineteen patients had a mild or severe hemiparesis. Five patients had a normal examination in the supine position but the onset of a deficit was noted when they assumed an upright position. One patient had a minor fixed speech deficit, and one patient had progressive blindness from venous stasis retinopathy. Vascular Pathology. Eighteen of the 26 patients had occlusion of the ICA, five had carotid siphon stenoses, two had MCA occlusion, and one had MCA stenosis. Giant Aneurysms in the Anterior Circulation Twenty patients had giant aneurysms in the anterior circulation. A typical computerized tomography scan and pre- and postoperative angiograms from a case in this group are illustrated in Figs. 12 and 13. FIG. 12. Preoperative studies in a woman who was admitted to the hospital with a 4-year history of headache, loss of vision in the left eye, and diplopia. On neurological examination, she had a total left third nerve palsy and a visual field defect compatible with left optic nerve compression. Left: Computerized tomography scan demonstrating a giant aneurysm arising in the left parasellar area. Right: Angiogram confirming the presence of a giant aneurysm, which only partially fills. Symptoms. One patient presented with symptoms of a subarachnoid hemorrhage and four patients were diagnosed from their history as having sustained a bleed. The remainder of the patients in this group presented with symptoms related to the size of the aneurysm, such as headaches, visual problems, speech difficulty, or hemiparesis. Progressive unrelenting unilateral headache was the most common symptom. Examination. One patient had a normal neurological examination but was experiencing headache from mass effect at the time of admission to the hospital. One patient was hemiplegic prior to the bypass procedure, and four patients had a mild hemiparesis. Fourteen patients had evidence of unilateral or bilateral optic nerve compression. Vascular Pathology. Four aneurysms were located at the bifurcation of the MCA and all others arose from the ICA. In the latter group, three were located at the bifurcation of the ICA, four arose near the area of the posterior communicating artery and projected inferiorly and medially, five arose in the paraclinoidal area and projected laterally and superiorly, and two were extradural in the proximal site from the transverse portion of the ICA. Two patients had bilateral giant aneurysms. Graft Patency Results of Treatment Graft patency can easily be determined in these cases by merely palpating the pulse of the saphenous vein anterior to the ear. This pulse is similar in quality to a carotid artery pulse, and it is not necessary to search for it as is often required with temporal artery pulses. Absence of the pulse is equated with occlusion of the graft. Graft patency is summarized for both the 446 J. Neurosurg. / Volume 65/October, 1986

9 Vein graft bypass for intracranial vascular disease FIG. 14. Intraoperative graft blood flows (in ml/min) through grafts in the anterior and posterior circulation indicate in general a slightly higher proportion of high flows in the anterior than in the posterior circulation procedures. The mean graft flow for anterior circulation procedures was 110 ml/min, and mean graft flow for posterior circulation procedures was 100 ml/min. FIG. 13. Postoperative angiograms in the same patient as depicted in Fig. 12 demonstrating good flow through the saphenous vein bypass graft, which extends from the stump of the ligated internal carotid artery in the neck to the M2 segment of the middle cerebral artery. Follow-up neurological examination was normal except for a partial third nerve palsy. Ultimately, the headaches disappeared and the patient is now fully employed. anterior- and posterior-circulation bypass groups in Table 1. Graft Blood Flow Intraoperative graft blood flows were determined using an electromagnetic flowmeter. Postoperative graft flows were estimated from a determination of the diameter of the graft on angiography and a Doppler velocity probe that indicates the velocity of flow through the graft. Intraoperative blood flow measurements are summarized in Fig. 14. Postoperative blood flow measurements indicated a gradual increase in flow over the first 72 hours with stabilization of flows thereafter. In general, calculated postoperative flows agreed well with intraoperative blood flow measurements. Operative Results Results in patients with bypass vein grafts for intracranial occlusive disease, including deficits existing prior to surgery, are summarized in Table 2. Posterior Circulation Ischemia. Neurological function was improved over the preoperative status in 58% of the 77 patients with posterior circulation ischemia and was unchanged in 16% at 1 month after the date of surgery. These patients were free of recurring ischemic events. In 13%, the deficit was greater than that reported prior to surgery. There was a 13% mortality rate within 1 month after surgery. TABLE 1 Patency of vein grafts in the anterior and posterior circulation Patency Status No. of Grafts patent* 111 acute occlusion 17 late occlusion (after 30 days) 4 total grafts 132 % patency 84 * Includes three vessels with acute occlusions that became patent after reoperation. TABLE 2 Results of bypass vein grafts in 132 patients Neurological Posterior Circulation Anterior Circulation Outcome* Ischemia Aneurysms Ischemia Aneurysms excellent good poor dead total cases * For definition of neurological outcome see text. Giant Aneurysms in the Posterior Circulation. There was only one excellent result among the nine patients with giant aneurysms in the posterior circulation; three patients had a good result. There was one poor result (this patient was hemiplegic prior to surgery), and four patients died. Three of the deaths occurred among the four patients with fusiform aneurysms involving the basilar artery trunk. Anterior Circulation Ischemia. Of the 26 patients with anterior circulation ischemia, five had excellent J. Neurosurg. / Volume 65/October,

10 T. M. Sundt, Jr., et al. TABLE 3 Operative complications related to vascular disease group Type of Complication Posterior Circulation Anterior Circulation Ischemia Aneurysms Ischemia Aneurysms graft occlusion reoperation no reoperation deficit from temporarily occluding recipient vessel permanent transient homonymous field deficit permanent transient stroke from occlusion of bypassed vessel 5 4* 0 0 subdural hygroma symptomatic asymptomatic paroxysmal lateralizing epileptiform discharges hemorrhage from giant aneurysm intracerebral hyperperfusion with hemorrhage major (death) minor (no deficit) intracerebral retraction hematoma requiring surgery subdural hematoma myocardial infarction pulmonary embolus * Ligation was a planned stage of the operation. results and 10 had good results. However, six patients (all of whom were hemiparetic or hemiplegic prior to surgery) were in poor condition, and five died. Four of the five deaths were secondary to intracerebral hemorrhage and one resulted from graft occlusion. All patients with hemorrhage had undergone surgery for a slowstroke syndrome. The graft occlusion occurred in a graft originating from the subclavian artery. Giant Aneurysms in the Anterior Circulation. Of the 20 patients with anterior circulation aneurysms, l0 had excellent results and six had good results. Three patients were in poor condition and one died. Complications Complications for all groups are summarized in Table 3. It should be noted that all occlusions of the bypassed vessel occurred in the basilar artery. In the four cases in which the basilar artery had been bypassed for fusiform aneurysms, this occlusion was iatrogenic and all four patients died from this occlusion. A basilar stenosis progressed to occlusion in five cases and in each of these a brain-stem infarction occurred. Three of these developed in patients with tandem lesions and two in patients with focal stenoses. In this group, three patients died and two survived with a "locked-in" syndrome. Follow-up Findings In the patients with posterior circulation ischemia, the mean follow-up period was 1 89 years (range 1 to 5 years). Two patients with excellent postoperative results suffered strokes during that period; one was a minor stroke from which the patient recovered fully and the other was a major stroke with the patient requiring nursing care thereafter. One patient who was categorized postoperatively as having a poor result had a minor stroke in the follow-up period but ultimately improved to a good recovery. Four patients had TIA's. Six patients died during this time: three from myocardial infarction, two from cerebrovascular causes, and one from cancer. For patients with giant aneurysms in the posterior circulation, the mean follow-up period was l~ years (range 6 months to 4 years). Neurological status in the survivors at follow-up examination remained as reported under Operative Results (above) except for one patient with a good result who died from pulmonary causes. The mean follow-up period for patients with anterior circulation ischemia was 1 year (range 6 months to 4 years). All patients retained their postoperative neurological function in the follow-up period except for one patient (a poor result) who had diffuse disease preoperatively ("radiation arteritis" from the treatment of a pituitary tumor) and had a brain-stem stroke. He eventually died 3 89 years after surgery from cerebrovascular causes. Two other patients died in the follow-up period: one of cardiac causes and one from sepsis. The patients with giant aneurysms in the anterior circulation had a mean follow-up period of 21 years (range 6 months to 4 years). Fifteen of the 16 patients who had an excellent or good operative result remained well in the follow-up period. One patient died from a myocardial infarction. 448 J. Neurosurg. / Volume 65/October, 1986

11 Vein graft bypass for intracranial vascular disease Discussion Indications and Results of Surgery Posterior Circulation Ischemia. Indications for vein bypass grafts in the treatment of posterior circulation ischemia have been reviewed in detail previously. 9 Essentially, these operations are reserved for patients who are neurologically unstable and have evidence of progressing symptoms of posterior circulation ischemia in spite of anticoagulant therapy and optimal medical management. Thus, they represent a very highrisk group of individuals. Giant Aneurysms in the Posterior Circulation. The indications for posterior circulation bypass procedures in patients with giant aneurysms in the posterior circulation appear to be few. Large fusiform aneurysms of the basilar trunk have not done well following vertebral artery ligation, in spite of the fact that the bypass graft itself remained patent. These patients have a dreadful disease and essentially a hopeless prognosis, so perhaps it is still worthwhile to consider this form of surgery in isolated cases. However, no general recommendation can be made regarding the advisability of surgery for these patients. These people are often suffering from both ischemia and mass effect of the aneurysm itself) With ligation of the vertebral artery and/or trapping of the aneurysm, the aneurysm itself expands creating additional mass effect which must be prevented by a partial excision of the lesion. Thus, surgery in these patients is a major undertaking and is considered as a last resort. Anterior Circulation Ischemia. Vein bypass grafts are indicated for patients who are suffering from major symptoms of anterior circulation ischemia in whom an adequate superficial temporal artery is not available for a bypass graft or in whom immediate high flows are desired. However, the risks of hemorrhage from hyperperfusion in this group are considerable and therefore the surgery must be undertaken very cautiously. Giant Aneurysms in the Anterior Circulation. We believe that vein bypass grafting has considerable value in the management of giant aneurysms in the anterior circulation. Hemorrhage from hyperperfusion has not occurred in this group; however, hemorrhage from the aneurysm itself secondary to a redirection of flow has occurred in two patients and it is therefore important to ligate the MCA at its point of exit from the aneurysm when the aneurysm is located at the bifurcation of the ICA. Analysis of Complications Graft Occlusion. Most of our graft occlusions occurred early in our experience and were related to technical problems. These are reviewed under Surgical Technique (above), but perhaps it is worthwhile to reemphasize some of them here. Preparation of the vein is extraordinarily important. The vein should not be overdistended and proper ori- entation of the vein is mandatory. In that this is a long vein graft following a circuitous course, we believe that it is best to mark this orientation of the vein with a Garrett line as indicated above. The distal anastomosis should be constructed such that the graft inflow into the PCA is on an angle. Not infrequently, a certain degree of atherosclerosis will be present in the PCA at the site of the intended anastomosis. One should not attempt endarterectomy as it is difficult to find a clean breaking point in the wall of the vessel and avoid a ledge of intima. Rather, it is best to take deep sutures which grip the entire thickness of the plaque and thus affix the wall of the atherosclerotic vessel to the anastomosis. The continuous suture lines should be held under tension while being placed. Failure to keep the sutures tight will result in leakage at the site of the anastomosis. This will require multiple additional interrupted sutures and lead to considerable bleeding with restoration of flow. The proximal anastomosis has to be constructed in such a fashion that there is as little turbulence as possible at the transition point between the carotid arteries and graft or between the subclavian artery and the graft. It is for this reason that we have employed various techniques in order to assure good inflow into the graft. Early in our series we used an aortic punch (Goosen punch) but, with further experience, we have found that an end-to-side anastomosis through an opening this size in the carotid artery (which is frequently atherosclerotic) gives insufficient flow into the graft. It is far better to use one of the construction methods detailed in Figs. 5 through 8. An end-to-end anastomosis to the ECA is preferable to an end-to-side anastomosis. Ischemic Stroke. There has not been a high incidence of stroke from the period of temporary vessel occlusion in these patients. As indicated in Table 3, some ischemic strokes were attributable to this cause but fortunately they have not been common. However, early in our experience, we did have two major strokes from Mj occlusion. Since those complications, we have avoided placing the distal anastomosis into the M~ segment and have preferred the M2 segment of the MCA. Hyperperfusion Breakthrough. Fortunately, hyperperfusion breakthrough with hemorrhage has not been a major problem in the posterior circulation bypass procedures, but it has presented a high risk in bypass surgery for anterior circulation ischemia. In fact, the danger of hyperperfusion breakthrough in patients with anterior circulation ischemia is serious enough that we have reserved the procedure for only a very few patients with symptoms of anterior circulation ischemia. Graft Longevity Graft longevity of the four vessels that became occluded in the follow-up period was indirectly related to technical problems. One graft occlusion occurred in the J. Neurosurg. / Volume 65 /October,

12 T. M. Sundt, Jr., et al. only patient in whom a major trunk was not used as a recipient vessel. This patient was the first in the series and the anterior temporal branch of the PCA was the recipient vessel. Two late graft occlusions were related to disproportion between the vein graft and the recipient vessel. In these, the saphenous vein had been harvested from the thigh and a 12- to 14-mm diameter saphenous vein was anastomosed to the PCA. The graft remained open initially but flow through the graft was slow as demonstrated by the Doppler probe, and turbulence at the distal site of the anastomosis was identified on angiography. This graft became occluded about 3 months postoperatively. One other late graft occlusion was associated with a very small saphenous vein measuring only 3.5 mm in external diameter. In our experience, if a properly constructed graft has remained patent for 1 week, it will remain patent. Patients are routinely maintained on antiplatelet therapy, usually with both aspirin and dipyridamole. 1'2 Conclusions Patency of bypass grafts can be maintained in the vast majority of cases and the flows delivered are a great deal higher than those achieved through a temporal artery pedicle. 5,7-9 Considering the gravity of neurological dysfunction in these patients, we believe the results in this series are good. Consideration is being given to a randomized trial of medical versus surgical therapy for patients with vertebrobasilar occlusion or stenoses who are not neurologically unstable. However, the seriousness of the illness and severity of symptoms in patients reported here make them ill-suited subjects for such a trial. Furthermore, all patients had already failed medical management. It has been approximately 16 years since Lougheed, et al.,6 reported the first case of a saphenous vein bypass graft, yet enthusiasm for this approach is still great. However, with increased knowledge acquired from the use of vein grafts in coronary artery surgery the future may be brighter, particularly in light of the report of the randomized trial of temporal artery to MCA bypass procedures. 4 Acknowledgment The authors appreciate the assistance of Ms. Bernita Bruns in the preparation of this manuscript. References 1. Chesebro JH, Clements IP, Fuster V, et al: A plateletinhibitor-drug trial in coronary-artery bypass operations. Benefit of perioperative dipyridamole and aspirin therapy on early postoperative vein-graft patency. N Engl J Med 307:73-78, Chesebro JH, Fuster V, Elveback LR, et al: Effect of dipyridamole and aspirin on late vein-graft patency after coronary bypass operations. N Engl J Med 310: , Drake CG: Giant intracranial aneurysms: experience with surgical treatment in 174 patients. Clin Neurosurg 26: 12-95, The EC/IC Bypass Study Group: Failure of extracranialintracranial arterial bypass to reduce the risk of ischemic stroke. Results of an international randomized trial. N Engl J Med 313: , Little JR, Furlan A J, Bryerton B: Short vein grafts for cerebral revascularization. J Neurosurg 59: , Lougheed WM, Marshall BM, Hunter M, et al: Common carotid to intracranial internal carotid bypass venous graft. Technical note. J Neurosurg 34: , Spetzler RF, Rhodes RS, Roski RA, et al: Subclavian to middle cerebral artery saphenous vein bypass graft. J Nenrosurg 53: , Story JL, Brown WE Jr, Eidelberg E, et al: Cerebral revascularization: common carotid to distal middle cerebral artery bypass. Neurosurgery 2: , Sundt TM Jr, Piepgras DG, Houser OW, et al: Interposition saphenous vein grafts for advanced occlusive disease and large aneurysms in the posterior circulation. J Neurosurg 56: , Zeal AA, Rhoton AL Jr: Microsurgical anatomy of the posterior cerebral artery. J Neurosurg 48: , 1978 Manuscript received January 2, Address reprint requests to: Thoralf M. Sundt, Jr., M.D., Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota J. Neurosurg. / Volume 65/October, 1986