J Neurosurg 77:941-944, 1992
Angioplasty for basilar artery atherosclerosis Case report ARVIND AHUJA, M.D., LEE R. GUTERMAN, PH.D., M.D., AND LEO N. HOPKINS, M.D. Departments of Neurosurger.v and Radiology, School of Medicine and Biomedical Sciences, State University of New York, Buffalo, New York ~" A case is presented of severe atherosclerosis of the basilar artery, successfully treated with percutaneous transluminal balloon angioplasty. Crescendo daily transient ischemic attacks consisted of alternating hemiplegia and were refractory to medical management, including anticoagulation therapy. The clinical course, endovascular treatment, and results are described. Prior published experiences with this condition are reviewed. KEY WORDS
9
9 atherosclerosis basilar artery vertebrobasilarinsufficiency
angioplasty
percutaneous surgery
p
ERCUTANEOUS transluminal angioplasty is being used successfully to treat atherosclerosis of the coronary, subclavian, vertebral, and peripheral arteries. However, there are few reports on the use of this procedure to treat disease of the basilar artery because of the technological limitations involved and the initially discouraging results) 9"~~We present a symptomatic case of atherosclerotic basilar artery stenosis treated successfully by angioplasty with a dilatation catheter system. This investigational system,* unlike earlier devices, employs a catheter of graded stiffness and an inflatable balloon that is placed into the proper location with a steerable guidewire.
30 to 45 minutes. He also complained of TIA's on rotation of his head. Since he had not improved on antiplatelet therapy, anticoagulation therapy with warfarin was instituted. After the prothrombin time (PT) was increased to one and one-half times baseline, the patient continued to suffer TIA's of alternating hemiplegia at a rate of 10 to 12 per day. Anticoagulation therapy was continued for 3 months; however, the TIA's persisted with increasing frequency. An extracranial-intracranial (EC-IC) ar-
Case Report This 68-:y'ear-old white man with coronary artery disease experienced a transient sensation of lightheadedness and right-sided hemiplegia lasting 30 minutes. Examination. Angiography revealed minimal carotid artery disease and a 95% stenosis of the basilar artery, cephalic to the origin of the posterior inferior cerebellar artery (PICA) (Fig. 1). He was placed on a course of antiplatelet therapy but continued to experience transient ischemic attacks (TIA's) of alternating hemiplegia with facial numbness that resolved within
* Stealth dilatation system manufactured by Target Therapeutics, Freemont, California.
J. Neurosurg. / Volume 77/December, 1992
FIG. 1. Preoperative angiogram, anteroposterior view, showing severe stenosis of the midbasilar artery (arrow). 941
A. A h u j a , L. R. G u t e r m a n , a n d L, N. H o p k i n s
FIG. 3. Postangioplasty angiogram, anteroposterior view, demonstrating a change in the shape of the plaque and enlargement of the vessel lumen (arrow).
FIG. 2. Photographs showing the Stealth dilatation system set-up with the graduated inflation syringe (tq)per) and an inflated balloon 2.5 mm in diameter with a 0.014-in. occluding wire in place (lower).
terial bypass procedure was considered but believed to be too risky in view of the patient's unstable neurological condition and coronary artery disease. Operation, Four months after experiencing the initial TIA and 3 months after being fully anticoagulated, the patient was admitted for basilar artery angioplasty. Twelve hours before the procedure, warfarin was reversed with fresh frozen plasma. A course of heparin was begun which could easily be reversed. The procedure was performed in the angiography suite under sedation with Versed (midazolam hydrochloride); however, the patient remained conscious enough to be examined neurologically. A No. 5.5 French guide catheter]" was inserted through the right femoral artery, positioned in the right vertebral artery, and then advanced to the C-2 level. A Stealth angioplasty balloon catheter was bench-tested with nonionic, full-strength Isovue 260 contrast medium~ at pressures up to 80 psi (Fig. 2 upper). A balloon with a maximum diameter of 2.5 mm at 80 psi was selected. A 0.014-in. Teflon-coated steerable guidewirew was placed through the balloon catheter with the wire protruding past the end of the balloon (Fig. 2 lower). With a real-time digital subtraction angiography technique, the balloon catheter (with guidewire) was placed i Guide catheter manufactured by Cook Co., Bloomington, Indiana. :~Contrast medium manufactured by E.R. Squibb and Sons, Inc., Princeton, New Jersey. wGuidewire manufactured by Target Therapeutics, Freemont, California. 942
through the guide catheter and maneuvered into the distal basilar artery beyond the area of stenosis. The steerable guidewire was then replaced with a special occlusion wire that allows closure of the distal part of the balloon for inflation. The balloon was positioned distal to the stenosis and test-inflated under fluoroscopy. The occluding valve wire was locked in place with a torque device. The balloon was withdrawn across the stenosis and inflated to 20 psi initially and subsequently up to 80 psi, in 20-psi increments, for up to 5 to 10 seconds per inflation. During angioplasty, there was no change in the patient's neurological status. Postoperative Course. Angiography performed immediately postangioplasty showed a reduction of the stenosis (Fig. 3). The patient remained on a course of heparin which was subsequently converted to warfarin therapy. Postoperatively, he had two episodes of transient numbness in the left facial region and right shoulder without any weakness. Angiography performed 10 days postangioplasty showed continued patency of the basilar artery. The patient remained asymptomatic for 3 months after angioplasty until he developed transient left lower-extremity weakness. On readmission, his PT was 12.2 msec. After heparinization with increased warfarin dosage, his PT increased to 20.6 rnsec. He noted no further neurological episodes until 5 months following angioplasty when he experienced ataxia and slurred speech for a period of 15 minutes. At that time, he had a low PT value which improved after adjustment of the warfarin dosage; he did not suffer any further neurological deterioration. Angiography at 6 months after the procedure demonstrated complete occlusion of the midbasilar artery with collateral supply from the posterior communicating artery, the PICA, and the anterior inferior cerebellar artery. The patient has remained asymptomatic during the subsequent 2 years.
J. Neurosurg, / Volume 77 / December, 1992
A n g i o p l a s t y for b a s i l a r a r t e r y a t h e r o s c l e r o s i s Discussion Basilar A rico' A therosch, rosis
The clinical signs of basilar artery stenosis and occlusion are identical. 3 According to Castaigne, et al.,4 most infarcts in the vertebrobasilar circulation result from thrombosis of the atherosclerotic lesion. In 1946, Kubik and Adams ~ studied 18 postmortem cases of basilar artery, occlusion and emphasized the abrupt onset of symptoms. Archer and Horenstein ~studied 20 patients who had severe neurological deficits and confirmed basilar artery occlusion angiographically. Meyer, et al., s emphasized the frequency of abnormality in the basilar artery in 35 patients with occlusive disease of the posterior circulation. Two patients in their series had complete occlusion of the basilar artery and were clinically asymptomatic. Caplan 2 analyzed the clinical course of six patients who survived occlusion of the basilar artery. In this group, TIA's were quite frequent in four of the six patients, occurring 1 month before the final stroke. Later, Caplan 3 concluded from his series and a review of the literature that the outcome in patients with basilar artery occlusive disease is quite variable; while some patients survive with little or no deficit, others die or are left severely disabled. He also noted that the critical period for acquisition of a central nervous system deficit depends primarily on the development of adequate collateral circulation and the presence of distal embolization at the time of occlusion. Prognosis depends on rapidity of the occlusion, location and extent of the thrombus, and the presence or absence of adequate collateral flow. Most infarctions are preceded by TIA's, which provide a therapeutic window of opportunity. In most patients, vertebrobasilar insufficiency can be treated medically with antiplatelet and anticoagulation therapy. If the patient is not responsive to medical treatment, there are limited options to prevent a vascular accident. Although EC-IC arterial bypass remains one of the options, the procedure can be associated with significant morbidity, particularly in neurologically unstable patients. 6 Angioplasty is another alternative for those patients who fail medical therapy. Our patient with severe vaso-occlusive disease of the basilar artery had TIA's that were not responsive to antiplatelet and anticoagulation therapy. Due to the patient's coronary artery disease and hence possible morbidity and death from an EC-IC bypass, angioplasty of the basilar artery was preferred. Previous A ngioplasty Procedures
Angioplasty of the basilar artery for vaso-occlusive disease has been reported by Sundt, et al., 9~~ in three patients who were unresponsive to anticoagulation therapy. All three patients underwent surgical exposure of the vertebral artery under general anesthesia for placement of the angioplasty balloon into the basilar artery. The authors considered that the balloon could not be J. Neurosurg. / Volume 77/December, 1992
placed percutaneously because of the tortuosity of the vertebral arteries. Within 24 hours after angioplasty, two of the three patients had one episode of TIA which resolved completely. The third patient had an episode of T1A within the 1st week after angioplasty. The TIA's were believed to have been caused by vasospasm of the artery and were treated with calcium channel blockers. Two of the three patients were asymptomatic at 26 and 30 months after angioplasty. The third developed a pseudoaneurysm at the site of dilatation 20 days postangioplasty and died when it ruptured 26 days later. Higashida, el al., ~ reported a patient with tandem stenotic basilar lesions. During initial angioplasty, a soft flow-directed balloon was deformed by atherosclerotie plaque. The patient underwent a second angioplasty under general anesthesia and barbiturate coma, and the vertebral artery was surgically exposed and cannulated. Unfortunately, this patient developed a brain-stern infarct. The disadvantages of previous embolization procedures include the necessity of surgical exposure of the vertebral artery for introduction of the balloon 5~~~and, in one case, the deformation of a soft balloon by plaque. 5 Piepgras, el al., 9 and Higashida, et al., ~ used flow-directed balloons inserted via surgical exposure of the vertebral artery under general anesthesia. Under such circumstances, balloon placement is difficult. R e c o m m e n d e d Angioplasty Technique
The dilatation system used in the current case consists of a single-lumen balloon attached to a steerable catheter. The balloon has a distal lumen wide enough for a guidewire to be placed distal to the balloon, and the balloon can be tracked over the wire through a percutaneous approach. Percutaneous transluminal angioplasty allows the procedure to be performed in an awake patient. This facilitates neurological monitoring, which may reduce risk. After adequate placement, the guidewire can be replaced with another (occlusion) wire with distal dilatation that acts as a valve to seal offthe distal end of the balloon section, allowing the balloon to be inflated (Fig. 2 lower). The superior flexibility of a single lumen allows access to lesions in distal tortuous vasculature. The system's ability to transmit axial forces (its "pushability") can be enhanced by pressing the valve portion of the wire against the distal end of the catheter and advancing both catheter and wire as a unit. This open-ended system also allows injection of contrast medium during the procedure. In addition, a radiopaque coil fused in the balloon section allows fluoroscopic visualization of the entire length of the balloon and improves its placement. The system has a working pressure of 60 to 80 psi and an inflation/deflation time of less than 4 seconds. Several other important technical points were learned in managing this case. For angioplasty, full-strength contrast medium should be used in order to fully visualize balloon inflation/deflation under real-time digital 943
A. A h u j a , L. R. G u t e r m a n , a n d L. N. H o p k i n s subtraction angiography. When possible, the inflated angioplasty balloon should first be maneuvered distal to the stenosis, then pulled back (uninflated) across the stenotic segment. Angioplasty is then carried out with the catheter under slight tension to minimize wandering of the balloon during inflation. Otherwise, there might be significant play in the system, allowing the balloon to migrate out of the stenotic area. Angioplasty should be carried out by increments for short periods of time to avoid prolonged occlusion of perforating vessels and to allow gradual opening of the stenotic vessel. Sudden maximal enlargement might predispose the vessel to damage by dissection or rupture. A torque device helps to lock the wire into the proper position in the catheter and to prevent migration of the wire. Angiography should be carried out intermittently during the procedure to determine the progress of angioplasty and to document any intimal disruption. Intracranial angioplasty need not be carried beyond 50% to achieve a significant improvement in flow, as evidenced by the dramatic clinical improvement in this case. Although more aggressive angioplasty results in a lower incidence of recurrent stenosis in coronary and peripheral vessels, we hesitate to dilate to more than 50% in intracranial vessels because of the lack of supporting tissues and the resulting risk of vessel rupture. A vessel lumen of 50% will allow adequate cerebral blood flow. The purpose of angioplasty should be to provide enough perfusion to reduce ischemic symptoms, not to provide angiographic "cure." This may help to prevent the rupture of the basilar artery observed by Piepgras, et air The average inside diameter of the midbasilar artery is 3 mm (unpublished data). Most angioplasty balloons have a maximum inflation greater than 3 ram, which predisposes vessels to excessive dilatation and possible change. The system used in the current case has graduated inflation diameters down to 2 mm and uniform pressure-modulated inflation, features that seem to be ideal for safe effective intracranial angioplasty. We suggest always starting with the smallest possible balloon for intracranial vessels and dilating it less than is recommended for peripheral and coronary vessels to provide an increased margin of safety. Although restenosis is more likely in this situation, the angioplasty may allow time for sufficient collateral vessels to develop and may result in an asymptomatic occlusion, as happened in this case.
944
Conclusions
This 68-year-old man with symptomatic atherosclerosis of the basilar artery did not benefit from medical therapy but was treated successfully by angioplasty. Angioplasty using proper instruments and technique may constitute suitable treatment of an otherwise lifethreatening stenosis of the basilar artery. In our patient, dilatation of the vessel provided the time needed to develop collateral blood flow, thus preventing the patient from suffering any permanent neurological deficit. Disclaimer
Target Therapeutics is the sole proprietor and distributor of the Stealth dilatation system. None of the authors has any proprietary interest in this product. References
1. Archer CR, Horenstein S: Basilar artery occlusion. Clinical and radiological correlation. Stroke 8:383-390, 1977 2. Caplan LR: Occlusion of the vertebral or basilar artery. Follow up analysis of some patients with benign outcome. Stroke 10:277-282, 1979 3. Caplan LR: Vertebrobasilar disease. Time for a new strategy. Stroke 12:111-114, 1981 4. Castaigne P, Lhermitte F, Gautier JC, et al: Arterial occlusions in the vertebrobasilar system. A study of 44 patients with post-mortem data. Brain 96:133-154, 1973 5. Higashida RT, Hieshima GB, Tsai FY, el al: Transluminal angioplasty of the vertebral and basilar artery. AJNR 8:745-749, 1987 6. Hopkins LN, Budny JL: Complications of intracranial bypass for vertebrobasilar insufficiency. J Nearosarg 70: 207-211, 1990 7. Kubik CS, Adams RD: Occlusion of the basilar artery - a clinical and pathological study. Brain 69:73-121, 1946 8. Meyer JS, Sheehan S, Bauer RB: An arteriographic study of cerebrovascular disease in man. 1. Stenosis and occlusion of the vertebral-basilar arterial system. Arch Neurol 2:27-45, 1960 9. Piepgras DG, Sundt TM Jr, Forbes GS, et al: Balloon catheter transluminal angioplasty for vertebrobasilar ischemia, in Berguer R, Bauer RB (eds): VertebrobasUar Arterial Occlusive Disease. Medical and Surgical Management. New York: Raven Press, 1984, pp 215-224
10. Sundt TM Jr, Smith HC, Campbell JK, et al: Transluminal angioplasty for basilar artery stenosis. Mayo Clin Proc 55:673-680, 1980 Manuscript received January 29, 1992. Accepted in final form May 14, 1992. Address reprint requests to: Leo N. Hopkins, M.D., Department of Neurosurgery, 3 Gates Circle, Buffalo, New York 14209.
J. Neurosurg. / Volume 77/December, 1992
Angioplasty for basilar artery atherosclerosis Case report ARVIND AHUJA, M.D., LEE R. GUTERMAN, PH.D., M.D., AND LEO N. HOPKINS, M.D. Departments of Neurosurger.v and Radiology, School of Medicine and Biomedical Sciences, State University of New York, Buffalo, New York ~" A case is presented of severe atherosclerosis of the basilar artery, successfully treated with percutaneous transluminal balloon angioplasty. Crescendo daily transient ischemic attacks consisted of alternating hemiplegia and were refractory to medical management, including anticoagulation therapy. The clinical course, endovascular treatment, and results are described. Prior published experiences with this condition are reviewed. KEY WORDS
9
9 atherosclerosis basilar artery vertebrobasilarinsufficiency
angioplasty
percutaneous surgery
p
ERCUTANEOUS transluminal angioplasty is being used successfully to treat atherosclerosis of the coronary, subclavian, vertebral, and peripheral arteries. However, there are few reports on the use of this procedure to treat disease of the basilar artery because of the technological limitations involved and the initially discouraging results) 9"~~We present a symptomatic case of atherosclerotic basilar artery stenosis treated successfully by angioplasty with a dilatation catheter system. This investigational system,* unlike earlier devices, employs a catheter of graded stiffness and an inflatable balloon that is placed into the proper location with a steerable guidewire.
30 to 45 minutes. He also complained of TIA's on rotation of his head. Since he had not improved on antiplatelet therapy, anticoagulation therapy with warfarin was instituted. After the prothrombin time (PT) was increased to one and one-half times baseline, the patient continued to suffer TIA's of alternating hemiplegia at a rate of 10 to 12 per day. Anticoagulation therapy was continued for 3 months; however, the TIA's persisted with increasing frequency. An extracranial-intracranial (EC-IC) ar-
Case Report This 68-:y'ear-old white man with coronary artery disease experienced a transient sensation of lightheadedness and right-sided hemiplegia lasting 30 minutes. Examination. Angiography revealed minimal carotid artery disease and a 95% stenosis of the basilar artery, cephalic to the origin of the posterior inferior cerebellar artery (PICA) (Fig. 1). He was placed on a course of antiplatelet therapy but continued to experience transient ischemic attacks (TIA's) of alternating hemiplegia with facial numbness that resolved within
* Stealth dilatation system manufactured by Target Therapeutics, Freemont, California.
J. Neurosurg. / Volume 77/December, 1992
FIG. 1. Preoperative angiogram, anteroposterior view, showing severe stenosis of the midbasilar artery (arrow). 941
A. A h u j a , L. R. G u t e r m a n , a n d L, N. H o p k i n s
FIG. 3. Postangioplasty angiogram, anteroposterior view, demonstrating a change in the shape of the plaque and enlargement of the vessel lumen (arrow).
FIG. 2. Photographs showing the Stealth dilatation system set-up with the graduated inflation syringe (tq)per) and an inflated balloon 2.5 mm in diameter with a 0.014-in. occluding wire in place (lower).
terial bypass procedure was considered but believed to be too risky in view of the patient's unstable neurological condition and coronary artery disease. Operation, Four months after experiencing the initial TIA and 3 months after being fully anticoagulated, the patient was admitted for basilar artery angioplasty. Twelve hours before the procedure, warfarin was reversed with fresh frozen plasma. A course of heparin was begun which could easily be reversed. The procedure was performed in the angiography suite under sedation with Versed (midazolam hydrochloride); however, the patient remained conscious enough to be examined neurologically. A No. 5.5 French guide catheter]" was inserted through the right femoral artery, positioned in the right vertebral artery, and then advanced to the C-2 level. A Stealth angioplasty balloon catheter was bench-tested with nonionic, full-strength Isovue 260 contrast medium~ at pressures up to 80 psi (Fig. 2 upper). A balloon with a maximum diameter of 2.5 mm at 80 psi was selected. A 0.014-in. Teflon-coated steerable guidewirew was placed through the balloon catheter with the wire protruding past the end of the balloon (Fig. 2 lower). With a real-time digital subtraction angiography technique, the balloon catheter (with guidewire) was placed i Guide catheter manufactured by Cook Co., Bloomington, Indiana. :~Contrast medium manufactured by E.R. Squibb and Sons, Inc., Princeton, New Jersey. wGuidewire manufactured by Target Therapeutics, Freemont, California. 942
through the guide catheter and maneuvered into the distal basilar artery beyond the area of stenosis. The steerable guidewire was then replaced with a special occlusion wire that allows closure of the distal part of the balloon for inflation. The balloon was positioned distal to the stenosis and test-inflated under fluoroscopy. The occluding valve wire was locked in place with a torque device. The balloon was withdrawn across the stenosis and inflated to 20 psi initially and subsequently up to 80 psi, in 20-psi increments, for up to 5 to 10 seconds per inflation. During angioplasty, there was no change in the patient's neurological status. Postoperative Course. Angiography performed immediately postangioplasty showed a reduction of the stenosis (Fig. 3). The patient remained on a course of heparin which was subsequently converted to warfarin therapy. Postoperatively, he had two episodes of transient numbness in the left facial region and right shoulder without any weakness. Angiography performed 10 days postangioplasty showed continued patency of the basilar artery. The patient remained asymptomatic for 3 months after angioplasty until he developed transient left lower-extremity weakness. On readmission, his PT was 12.2 msec. After heparinization with increased warfarin dosage, his PT increased to 20.6 rnsec. He noted no further neurological episodes until 5 months following angioplasty when he experienced ataxia and slurred speech for a period of 15 minutes. At that time, he had a low PT value which improved after adjustment of the warfarin dosage; he did not suffer any further neurological deterioration. Angiography at 6 months after the procedure demonstrated complete occlusion of the midbasilar artery with collateral supply from the posterior communicating artery, the PICA, and the anterior inferior cerebellar artery. The patient has remained asymptomatic during the subsequent 2 years.
J. Neurosurg, / Volume 77 / December, 1992
A n g i o p l a s t y for b a s i l a r a r t e r y a t h e r o s c l e r o s i s Discussion Basilar A rico' A therosch, rosis
The clinical signs of basilar artery stenosis and occlusion are identical. 3 According to Castaigne, et al.,4 most infarcts in the vertebrobasilar circulation result from thrombosis of the atherosclerotic lesion. In 1946, Kubik and Adams ~ studied 18 postmortem cases of basilar artery, occlusion and emphasized the abrupt onset of symptoms. Archer and Horenstein ~studied 20 patients who had severe neurological deficits and confirmed basilar artery occlusion angiographically. Meyer, et al., s emphasized the frequency of abnormality in the basilar artery in 35 patients with occlusive disease of the posterior circulation. Two patients in their series had complete occlusion of the basilar artery and were clinically asymptomatic. Caplan 2 analyzed the clinical course of six patients who survived occlusion of the basilar artery. In this group, TIA's were quite frequent in four of the six patients, occurring 1 month before the final stroke. Later, Caplan 3 concluded from his series and a review of the literature that the outcome in patients with basilar artery occlusive disease is quite variable; while some patients survive with little or no deficit, others die or are left severely disabled. He also noted that the critical period for acquisition of a central nervous system deficit depends primarily on the development of adequate collateral circulation and the presence of distal embolization at the time of occlusion. Prognosis depends on rapidity of the occlusion, location and extent of the thrombus, and the presence or absence of adequate collateral flow. Most infarctions are preceded by TIA's, which provide a therapeutic window of opportunity. In most patients, vertebrobasilar insufficiency can be treated medically with antiplatelet and anticoagulation therapy. If the patient is not responsive to medical treatment, there are limited options to prevent a vascular accident. Although EC-IC arterial bypass remains one of the options, the procedure can be associated with significant morbidity, particularly in neurologically unstable patients. 6 Angioplasty is another alternative for those patients who fail medical therapy. Our patient with severe vaso-occlusive disease of the basilar artery had TIA's that were not responsive to antiplatelet and anticoagulation therapy. Due to the patient's coronary artery disease and hence possible morbidity and death from an EC-IC bypass, angioplasty of the basilar artery was preferred. Previous A ngioplasty Procedures
Angioplasty of the basilar artery for vaso-occlusive disease has been reported by Sundt, et al., 9~~ in three patients who were unresponsive to anticoagulation therapy. All three patients underwent surgical exposure of the vertebral artery under general anesthesia for placement of the angioplasty balloon into the basilar artery. The authors considered that the balloon could not be J. Neurosurg. / Volume 77/December, 1992
placed percutaneously because of the tortuosity of the vertebral arteries. Within 24 hours after angioplasty, two of the three patients had one episode of TIA which resolved completely. The third patient had an episode of T1A within the 1st week after angioplasty. The TIA's were believed to have been caused by vasospasm of the artery and were treated with calcium channel blockers. Two of the three patients were asymptomatic at 26 and 30 months after angioplasty. The third developed a pseudoaneurysm at the site of dilatation 20 days postangioplasty and died when it ruptured 26 days later. Higashida, el al., ~ reported a patient with tandem stenotic basilar lesions. During initial angioplasty, a soft flow-directed balloon was deformed by atherosclerotie plaque. The patient underwent a second angioplasty under general anesthesia and barbiturate coma, and the vertebral artery was surgically exposed and cannulated. Unfortunately, this patient developed a brain-stern infarct. The disadvantages of previous embolization procedures include the necessity of surgical exposure of the vertebral artery for introduction of the balloon 5~~~and, in one case, the deformation of a soft balloon by plaque. 5 Piepgras, el al., 9 and Higashida, et al., ~ used flow-directed balloons inserted via surgical exposure of the vertebral artery under general anesthesia. Under such circumstances, balloon placement is difficult. R e c o m m e n d e d Angioplasty Technique
The dilatation system used in the current case consists of a single-lumen balloon attached to a steerable catheter. The balloon has a distal lumen wide enough for a guidewire to be placed distal to the balloon, and the balloon can be tracked over the wire through a percutaneous approach. Percutaneous transluminal angioplasty allows the procedure to be performed in an awake patient. This facilitates neurological monitoring, which may reduce risk. After adequate placement, the guidewire can be replaced with another (occlusion) wire with distal dilatation that acts as a valve to seal offthe distal end of the balloon section, allowing the balloon to be inflated (Fig. 2 lower). The superior flexibility of a single lumen allows access to lesions in distal tortuous vasculature. The system's ability to transmit axial forces (its "pushability") can be enhanced by pressing the valve portion of the wire against the distal end of the catheter and advancing both catheter and wire as a unit. This open-ended system also allows injection of contrast medium during the procedure. In addition, a radiopaque coil fused in the balloon section allows fluoroscopic visualization of the entire length of the balloon and improves its placement. The system has a working pressure of 60 to 80 psi and an inflation/deflation time of less than 4 seconds. Several other important technical points were learned in managing this case. For angioplasty, full-strength contrast medium should be used in order to fully visualize balloon inflation/deflation under real-time digital 943
A. A h u j a , L. R. G u t e r m a n , a n d L. N. H o p k i n s subtraction angiography. When possible, the inflated angioplasty balloon should first be maneuvered distal to the stenosis, then pulled back (uninflated) across the stenotic segment. Angioplasty is then carried out with the catheter under slight tension to minimize wandering of the balloon during inflation. Otherwise, there might be significant play in the system, allowing the balloon to migrate out of the stenotic area. Angioplasty should be carried out by increments for short periods of time to avoid prolonged occlusion of perforating vessels and to allow gradual opening of the stenotic vessel. Sudden maximal enlargement might predispose the vessel to damage by dissection or rupture. A torque device helps to lock the wire into the proper position in the catheter and to prevent migration of the wire. Angiography should be carried out intermittently during the procedure to determine the progress of angioplasty and to document any intimal disruption. Intracranial angioplasty need not be carried beyond 50% to achieve a significant improvement in flow, as evidenced by the dramatic clinical improvement in this case. Although more aggressive angioplasty results in a lower incidence of recurrent stenosis in coronary and peripheral vessels, we hesitate to dilate to more than 50% in intracranial vessels because of the lack of supporting tissues and the resulting risk of vessel rupture. A vessel lumen of 50% will allow adequate cerebral blood flow. The purpose of angioplasty should be to provide enough perfusion to reduce ischemic symptoms, not to provide angiographic "cure." This may help to prevent the rupture of the basilar artery observed by Piepgras, et air The average inside diameter of the midbasilar artery is 3 mm (unpublished data). Most angioplasty balloons have a maximum inflation greater than 3 ram, which predisposes vessels to excessive dilatation and possible change. The system used in the current case has graduated inflation diameters down to 2 mm and uniform pressure-modulated inflation, features that seem to be ideal for safe effective intracranial angioplasty. We suggest always starting with the smallest possible balloon for intracranial vessels and dilating it less than is recommended for peripheral and coronary vessels to provide an increased margin of safety. Although restenosis is more likely in this situation, the angioplasty may allow time for sufficient collateral vessels to develop and may result in an asymptomatic occlusion, as happened in this case.
944
Conclusions
This 68-year-old man with symptomatic atherosclerosis of the basilar artery did not benefit from medical therapy but was treated successfully by angioplasty. Angioplasty using proper instruments and technique may constitute suitable treatment of an otherwise lifethreatening stenosis of the basilar artery. In our patient, dilatation of the vessel provided the time needed to develop collateral blood flow, thus preventing the patient from suffering any permanent neurological deficit. Disclaimer
Target Therapeutics is the sole proprietor and distributor of the Stealth dilatation system. None of the authors has any proprietary interest in this product. References
1. Archer CR, Horenstein S: Basilar artery occlusion. Clinical and radiological correlation. Stroke 8:383-390, 1977 2. Caplan LR: Occlusion of the vertebral or basilar artery. Follow up analysis of some patients with benign outcome. Stroke 10:277-282, 1979 3. Caplan LR: Vertebrobasilar disease. Time for a new strategy. Stroke 12:111-114, 1981 4. Castaigne P, Lhermitte F, Gautier JC, et al: Arterial occlusions in the vertebrobasilar system. A study of 44 patients with post-mortem data. Brain 96:133-154, 1973 5. Higashida RT, Hieshima GB, Tsai FY, el al: Transluminal angioplasty of the vertebral and basilar artery. AJNR 8:745-749, 1987 6. Hopkins LN, Budny JL: Complications of intracranial bypass for vertebrobasilar insufficiency. J Nearosarg 70: 207-211, 1990 7. Kubik CS, Adams RD: Occlusion of the basilar artery - a clinical and pathological study. Brain 69:73-121, 1946 8. Meyer JS, Sheehan S, Bauer RB: An arteriographic study of cerebrovascular disease in man. 1. Stenosis and occlusion of the vertebral-basilar arterial system. Arch Neurol 2:27-45, 1960 9. Piepgras DG, Sundt TM Jr, Forbes GS, et al: Balloon catheter transluminal angioplasty for vertebrobasilar ischemia, in Berguer R, Bauer RB (eds): VertebrobasUar Arterial Occlusive Disease. Medical and Surgical Management. New York: Raven Press, 1984, pp 215-224
10. Sundt TM Jr, Smith HC, Campbell JK, et al: Transluminal angioplasty for basilar artery stenosis. Mayo Clin Proc 55:673-680, 1980 Manuscript received January 29, 1992. Accepted in final form May 14, 1992. Address reprint requests to: Leo N. Hopkins, M.D., Department of Neurosurgery, 3 Gates Circle, Buffalo, New York 14209.
J. Neurosurg. / Volume 77/December, 1992
