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Neuroradiology |
1 From the Departments of Radiology (W.Y., J.J.S., J.K.K., H.K.K.), Neurology (K.H.C., M.K.K., B.C.K., M.S.P.), and Neurosurgery (T.S.K.), Chonnam National University Hospital, Chonnam National University Medical School, 8 Hak-dong, Dong-ku, Gwangju 501-757, South Korea. Received September 20, 2004; revision requested November 24; revision received December 13; accepted January 14, 2005. Address correspondence to W.Y. (e-mail: radyoon{at}cnuh.com).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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MATERIALS AND METHODS: Institutional review board approval to perform angioplasty procedures for MCA stenosis was obtained, and written informed consent was obtained from each patient or the patient's family. Institutional review board approval was also obtained for the retrospective review of patients' data. The institutional review board waived the need for informed consent for this retrospective analysis.Thirty-two consecutive patients (18 men, 14 women; median age, 55 years) with symptomatic MCA stenosis greater than 70% underwent angioplasty between June 1994 and July 2003. The indication for angioplasty was recurrent transient ischemic attack (TIA) refractory to antithrombotic therapy in 24 patients and acute ischemic stroke in eight. Patient records were retrospectively reviewed for angiographic findings, periprocedural complications, and follow-up data.
RESULTS: Angioplasty reduced the degree of stenosis to less than 50% in 29 of 32 patients (91%). There were two major complications during angioplasty: acute occlusion of the treated MCA and vascular rupture that resulted in death. Thus, the risk of disabling stroke or death was 6% (two of 32 patients), and the mortality rate was 3% (one of 32 patients). The rate of periprocedural TIA was 19% (six of 32 patients). Five patients had asymptomatic intimal dissection. During the follow-up period, which ranged from 5 to 92 months (median, 20 months), TIA occurred in one patient in whom the results of angioplasty were suboptimal. The remaining 29 patients did not experience further ischemic events attributable to the treated MCA stenosis during the follow-up period. Asymptomatic restenosis occurred in one of five patients in whom data from follow-up angiography were available.
CONCLUSION: MCA angioplasty resulted in a low recurrence rate of ischemic symptoms during long-term follow-up.
© RSNA, 2005
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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With advances in device technology, intracranial angioplasty has emerged as a potential therapeutic option. At present, intracranial angioplasty is usually performed in patients with symptomatic intracranial internal carotid or vertebrobasilar arteries (8–17). The reports of intracranial angioplasty for symptomatic MCA stenosis remain insufficient, and most series have been limited in terms of the small number of MCA cases included or because of the lack of long-term follow-up. The purpose of our study, therefore, was to retrospectively review the outcome after angioplasty in 32 patients with symptomatic high-grade MCA stenoses refractory to medical therapy.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Our institutional review board approved the angioplasty procedure for MCA stenosis, and written informed consent was obtained from each patient or the patient's family. Approval from the institutional review board was also obtained for the retrospective review of patients' data. The institutional review board waived the need for informed consent for this retrospective analysis.
Procedures
All angiographic procedures and angioplasty were performed by one of two radiologists with 3 years (W.Y.) and 7 years (J.K.K.) of experience in neurovascular intervention. The patients received 325 mg of aspirin daily for at least 3 days before the procedure. A bolus of 3000–5000 U of heparin was given intravenously at the beginning of the procedure in all patients. All endovascular procedures were performed with the patient under local anesthesia. Complete diagnostic cerebral angiography was performed in each patient. The degree of MCA stenosis (S), expressed as a percentage, was measured by comparing the diameter of the vessel at the site of greatest stenosis (Dsten) with the normal diameter of the vessel just distal to the stenosis (Ddist), as follows: S = [1 – (Dsten/Ddist)] · 100 (20). Until 1999, vessel diameter was measured with software provided with the digital subtraction angiography equipment (Angiostar; Siemens Medical Systems, Erlangen, Germany) used for angiography. After that time, the measurement was derived from angiographic images obtained with biplane digital subtraction angiography equipment (Advantx LCN+; GE Medical Systems, Milwaukee, Wis) by using reference markers of known size applied to each patient's head.
A 6-F guiding catheter was inserted into the cervical portion of the internal carotid artery over an exchange wire. Since 2002 (from patient 17 to patient 32), abciximab (Reopro; Eli Lilly, Indianapolis, Ind) was given as a 0.25 mg per kilogram of body weight intravenous bolus along with heparin just after placement of the guiding catheter. The first 30 patients were treated with Stealth angioplasty balloons (Target Therapeutics, Fremont, Calif), and the last two patients were treated with coronary balloons (HayatePro; Terumo, Tokyo, Japan). With use of road mapping, the stenosis in the MCA was crossed with a 0.014-inch micro-guidewire and a balloon angioplasty catheter was introduced across the stenosis. The micro-guidewire was subsequently replaced by an occlusion valve wire when Stealth balloons were used. The size of the balloon catheter used was determined according to the size of the adjacent artery just distal to the stenosis. Until 1996 (for patients 1–5), the diameter of the balloon catheter was approximated to the diameter of the normal vessel and the balloon catheter was inflated for less than 30 seconds with a pressure of 6–8 atm (0.6–0.8 nm). Since 1997 (for patients 6–32), the diameter of the balloon was chosen to be 0.5 mm smaller than that of the normal vessel just distal to the stenosis. The balloon was inflated slowly with a screw-type pressure inflation device at 2–4 atm (0.2–0.4 nm) for 30–60 seconds up to two times. Follow-up angiography was performed by means of a guiding catheter after the procedure, and the degree of residual stenosis was recorded. Technical success was defined as a residual stenosis of less than 50% on follow-up angiograms without any serious complications (eg, vessel rupture, acute thrombotic occlusion of the MCA).
Postprocedural Management
After the procedure, a complete neurologic examination was performed in each patient by one of three neurologists (K.H.C., M.K.K., or B.C.K.). The arterial sheath was removed, and hemostasis was achieved with manual compression. Heparin was infused intravenously for 12–24 hours after the procedure. Antiplatelet medication was administered as it had been before the procedure. The National Institutes of Health Stroke Scale (NIHSS) score was recorded before treatment, 24 hours after treatment, and on the day of discharge.
After discharge, patients received daily doses of 325 mg of aspirin and 250 mg of ticlopidine or 75 mg of clopidogrel. Aspirin was administered for at least 1 year; ticlopidine or clopidogrel was discontinued after 3 months. All patients were followed up at regular intervals of 1–3 months in the outpatient clinic at our institution. Symptom recurrence was defined as cerebral ischemic events (eg, TIA or stroke) in the territory that angioplasty was performed during the follow-up period. In patients who initially had acute ischemic stroke, clinical outcomes were measured 3 months after the procedure with use of the modified Rankin scale. Restenosis was evaluated with catheter angiography or transcranial Doppler ultrasonography (US). Results of follow-up catheter angiography were available in five patients after 15–33 months (median, 19 months) (Fig 1). There was no specific indication for follow-up angiography in these patients. Baseline transcranial Doppler US examinations were performed before angioplasty in 27 patients. Follow-up transcranial Doppler US examinations were performed more than two times, usually at 3 months and 1 year after angioplasty, in 24 patients. Restenosis was defined as an increase in mean flow velocity of more than 30 cm/sec between two consecutive transcranial Doppler US examinations (2,21) or as an increase in the degree of residual stenosis measured on follow-up catheter angiograms. Follow-up information was obtained with chart review and/or telephone interview by one of two authors (W.Y. or J.J.S.).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Patients with Acute Ischemic Stroke before Angioplasty
Eight patients had an acute, nonfatal ischemic stroke before MCA angioplasty. The results of angioplasty in these patients are given in Table 2. Of these eight patients, five had an acute infarction in the ipsilateral MCA territory 4–8 weeks before angioplasty. Acute infarction was diagnosed on the basis of the findings seen on diffusion-weighted MR images obtained within 7 days of symptom onset. All five patients had subcortical infarcts; three (patients 1, 20, and 21) had deep perforator infarcts, one (patient 13) had superficial perforator infarcts, and one (patient 17) had combined subcortical infarcts. These patients underwent scheduled angiography and subsequent angioplasty after antithrombotic therapy. The NIHSS scores in these patients ranged from 1 to 9 (median, 8.5) before the procedure. Three of these five patients showed neurologic improvement, and their NIHSS scores 24 hours after treatment ranged from 1 to 6. Substantial improvements in motor weakness contributed to the decreased NIHSS score in these three patients. Two patients were neurologically unchanged after the procedure. All five patients had good clinical outcomes at 3 months: Three patients had a modified Rankin score of 0, and two had a score of 1.
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Angiographic Follow-up
Images from follow-up catheter angiography were available in five patients. The results of follow-up angiography are shown in Table 3. In one patient (patient 9) who had residual stenosis of 10% just after angioplasty, the degree of stenosis increased to 30% on angiograms obtained 33 months after angioplasty. This patient, however, did not have any ischemic symptoms during follow-up. No restenosis occurred in the remaining four patients. Thus, the symptomatic restenosis rate was 0% in five patients who underwent follow-up angiography. Twenty-four patients underwent serial transcranial Doppler US more than two times during the follow-up period. No patients in whom follow-up transcranial Doppler US data were available showed restenosis at transcranial Doppler US.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Patients with MCA stenosis are at high risk of further ischemic events despite medical treatment. In the extracranial-intracranial bypass study group, patients with stenosis in the MCA who received medical treatment had an annual stroke rate of 8%–10% (1). Arenillas et al (2) reported an annual ischemic event rate of 9.1% in 40 patients with symptomatic MCA stenosis who were receiving antiplatelet or anticoagulation agents. Wong et al (3) reported a recurrent ischemic event rate of 10.5% at 6 months after first stroke in 143 Asian patients with MCA occlusive disease detected at transcranial Doppler US. Recently, the Warfarin-Aspirin Symptomatic Intracranial Disease Study (23) was prematurely terminated owing to the high end-point results (ischemic stroke or brain hemorrhage) with both agents and the confirmed increased bleeding with warfarin. As a result of that study, the 1-year rate of stroke in the territory of the symptomatic intracranial stenosis was 11%–12% with medical therapy with either warfarin or aspirin (M. I. Chimowitz, written communication, December 2004). The results of these studies demonstrate the need for more effective treatment—other than drug therapy—for the prevention of future stroke. More invasive revascularization procedures, such as angioplasty and stent placement, may prove to be alternative methods in patients with intracranial atherosclerosis who are at high risk for stroke.
Results of previous studies have indicated that intracranial angioplasty may reduce the rate of further stroke in patients with intracranial atherosclerosis. Results of a retrospective study involving 23 patients (14), including three with MCA lesions, showed that the annual stroke rate was 3.2% in the region of the treated artery after intracranial angioplasty. Mori et al (12) reported a cumulative stroke risk of 8% 1 year after angioplasty in 12 patients with focal (5 mm or less in length) intracranial stenosis, including five with MCA stenosis. Alazzaz et al (16) reported their results in 15 patients, including five with MCA lesions, with a follow-up period of 1 month to 2 years in which two patients developed recurrent ischemic symptoms at 1 month and at 2 years. In the present study, 29 of 32 patients did not have further cerebral ischemic events attributed to MCA treatment during a follow-up period of 10–92 months (median, 20 months). On the basis of our results, we believe that intracranial angioplasty for symptomatic MCA stenosis refractory to drug therapy can be a promising alternative for reducing the risk of further TIA or stroke if it can be performed safely.
Intracranial angioplasty for the treatment of atherosclerotic stenosis has been associated with potential periprocedural risks, including arterial dissection, arterial rupture, and acute thrombotic occlusion. The major periprocedural complication rate associated with intracranial angioplasty has been reported to be 0%–50% in the literature (8–11,13–17). Connors and Wojak (15) described an overall periprocedural stroke or death rate of 7.1% (three strokes and two deaths) in 70 patients who underwent intracranial angioplasty for anterior and posterior circulation. Marks et al (14) reported one MCA rupture among 23 patients, including three with MCA stenosis, for a mortality rate of 4.3%. Alazzaz et al (16) reported a 13% stroke rate and no mortality in 15 patients, including five with MCA lesions. Recently, Gupta et al (17) reported a major complication rate of 50%, including 39% of cases that were hemorrhagic complications (17% intracranial and 22% extracranial), in 18 patients who underwent intracranial angioplasty for the treatment of impending stroke and neurologic instability. An aggressive combination of various antithrombotics, anticoagulants, and thrombolytics was mainly responsible for the high rate of hemorrhagic complications in that series of patients.
In the present study, two major complications, including one death, occurred during angioplasty. In one patient with a 95% diffuse stenosis in the distal M1 segment, angioplasty was performed with a 3-mm balloon and resulted in fatal rupture of that segment. Several factors—the large size of the balloon used, rapid inflation, and a long, high-grade stenosis—probably contributed to this arterial rupture. To avoid this event, extremely slow inflation with a screw-type inflation device is mandatory. The following is a brief description of our current angioplasty technique, which is especially focused on the prevention of vessel rupture: The balloon catheter is very slowly inflated for 30 seconds to 1 atm (0.1 nm), with monitoring of the pressure gauge on the inflation device; another 30 seconds are needed for holding on the pressure. Thus, the entire inflation time will be 4 minutes if the balloon catheter is inflated to 4 atm (0.4 nm). The balloon pressure should not exceed 6 atm (0.6 nm) and is usually in the range of 4–6 atm (0.4–0.6 nm). In addition, according to recommendations made by Connors and Wojak (15), the balloon is always undersized; the diameter of the balloon should always be 0.5 mm less than that of the normal vessel just distal to the stenosis.
Recently, several investigators reported the technical feasibility and safety of intracranial stent placement for the treatment of intracranial atherosclerotic stenosis (24–26). In comparison with intracranial angioplasty, stent placement theoretically can minimize the risk of acute vessel occlusion from dissection and decrease restenosis resulting from the recoil of atherosclerotic vessels. Intracranial stent placement, however, has potential hazards, such as arterial rupture, in-stent thrombosis, malposition of the stent, or the inability to pass the stent to the appropriate location. Furthermore, the reported complication rate of intracranial stent placement is high, especially in the MCA. In a retrospective study of intracranial stent placement in 12 patients because of symptomatic MCA stenosis, Kim et al (25) reported a major complication rate of 33%—including two vessel ruptures and two thromboembolic complications—and a mortality rate of 8.3%. In a relatively large series of primary stent placement, Jiang et al (26) used a coronary balloon stent in 40 patients with MCA stenosis and reported a procedural complication rate of 10%—including one acute vessel occlusion and three subarachnoid hemorrhages—and a mortality rate of 2.5%. In addition, data from long-term follow-up after intracranial stent placement are lacking to date.
Our study had several limitations. First, the rates of periprocedural TIA and stroke in this study may not reflect those of current state-of-the-art practices because the technique of angioplasty (with regard to balloon sizing, dilation pressure, and inflation time) has evolved during the 9-year study period. The rate of procedure-related complications in this study would be minimized if current techniques were used. In addition, only those patients who were treated in the last half of the study received a bolus of abciximab, a platelet glycoprotein IIb/IIIa receptor inhibitor that is currently considered effective for preventing acute thrombosis associated with neurovascular procedures. Another limitation of this study was that the follow-up imaging to evaluate restenosis was not perfect. Catheter angiography, which is a standard of reference, was performed in only a small number of patients. Although transcranial Doppler US was performed for follow-up in a large number of patients, it has several disadvantages in the diagnosis of MCA stenosis: The diagnostic transcranial Doppler US criteria for identifying MCA stenosis are variable, and concomitant stenoses in other cerebral arteries may cause over- or underestimation of the degree of MCA stenosis (27).
In conclusion, MCA angioplasty resulted in a low rate of recurrence of ischemic symptoms at follow-up in patients with symptomatic MCA stenosis refractory to medical therapy.
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FOOTNOTES |
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Abbreviations: MCA = middle cerebral artery • NIHSS = National Institutes of Health Stroke Scale • TIA = transient ischemic attack
Authors stated no financial relationship to disclose.
Author contributions: Guarantor of integrity of entire study, W.Y.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, W.Y.; clinical studies, all authors; statistical analysis, W.Y.; and manuscript editing, W.Y., J.J.S., K.H.C., H.K.K.
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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