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Vascular and Interventional Radiology |
1 From the Departments of Clinical Radiology (H.I.M., E.T.K., P.M.), Medicine (R.I., P.K., E.L.), and Radiotherapy (T.L.), Kuopio University Hospital, Puijonlaaksontie 2, PO Box 1777, FIN-70211 Kuopio, Finland. Received February 16, 2000; revision requested March 27; final revision received June 30; accepted July 25. Supported by a grant from Kuopio University Hospital. Address correspondence to H.I.M. (e-mail: Hannu.Manninen@kuh.fi)
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSION REFERENCES |
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MATERIALS AND METHODS: Altogether, 103 interventions were performed in 53 Brescia-Cimino shunts in 51 patients by means of antegrade brachial arterial access. Twelve interventions were initiated with pharmacomechanical thrombolysis and/or thromboaspiration. All interventions included balloon angioplasty that was completed with stent placement in eight cases and with endovascular brachytherapy with an iridium 192 source in five cases.
RESULTS: The technical success rate of the primary interventions was 92% (49 of 53) and that for all interventions was 95% (98 of 103). The rate of major complications was 4% (four of 103). Clinical success was achieved in 92% (95 of 103) of the interventions. By including the initial failures, 58% ± 7 (standard error of the estimate), 44% ± 8, 40% ± 8, and 32% ± 10 primary and 90% ± 5, 85% ± 5, 79% ± 7, and 79% ± 7 secondary clinical patency rates were registered at 6 months and 1, 2, and 3 years, respectively, by means of Kaplan-Meier analysis. The location of the main treated lesion at the arteriovenous anastomosis (P = .03) was a predictor of poorer long-term patency.
CONCLUSION: Endovascular interventions with antegrade brachial arterial access are highly effective in restoring function in failing Brescia-Cimino fistulas.
Index terms: Arteries, transluminal angioplasty, 91.454 • Dialysis, shunts, 91.1282, 91.442, 91.454, 91.457 • Grafts, interventional procedures, 91.1282, 91.454, 91.457 • Grafts, stenosis or thrombosis, 91.1282, 91.442, 91.454, 91.457 • Thrombolysis, 91.1265
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSION REFERENCES |
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The purpose of this prospective study was to evaluate the safety and efficacy of endovascular interventions via antegrade brachial arterial access in failing Brescia-Cimino hemodialysis fistulas.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSION REFERENCES |
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All patients provided informed consent, and the study protocol was approved by our hospital’s institutional review board for scientific trials. During the study period, eight patients underwent only diagnostic studies, without any further endovascular intervention; in five patients, intervention was not thought feasible, and in three patients no hemodynamically significant lesions were detected. These patients were not included in the study.
Patient Population and Indications for Endovascular Intervention
During the study period, endovascular interventions were performed in 53 failing antebrachial end-to-side Brescia-Cimino fistulas (the site of the anastomosis was a few centimeters proximal to the wrist joint) in 51 patients (29 men, 22 women; mean age, 59 years; median age, 65 years; age range, 22–80 years). The signs indicating the need for angiography and endovascular therapy are listed in Table 1. The mean functional time of the fistula before the first endovascular intervention was 10.5 months (median time, 9.5 months; range, 0–72.0 months).
All interventions included PTA of the occluded and/or stenotic segments with stenosis of more than 50% of the diameter. If small amounts of thrombus were seen, aspiration through the introducer sheath was used. In cases of total occlusion and a considerable amount of visible thrombus, selective thrombolysis was performed. The indication for stent placement was inadequate PTA results: residual stenosis exceeding 50% and/or a flow-limiting dissection. From the beginning of 1998, PTA for intrastent restenosis was completed with endovascular brachytherapy to prevent further restenosis. Furthermore, endovascular brachytherapy was used in cases with less than 3 months between interventions for restenosis of the same antebrachial venous lesion.
Technique Used in the Endovascular Interventions
All endovascular interventions were initiated by means of angiography of the fistula through an antegrade, high brachial arterial puncture with a 17-gauge needle. The angiographic study was considered to give sufficient diagnostic information about the afferent radial artery and efferent veins up to the level of the caval vein in every case, and there were no failures in accessing the brachial artery. For the endovascular treatments, a 12-cm-long, 5- or 6-F introducer sheath was inserted with the aid of digital road mapping control, and 5,000 units of heparin was administered intraarterially.
The stenosed or occluded segments were traversed with a hydrophilic guide wire, and balloon angioplasty (mean balloon diameter, 5.5 mm; range, 3.0–8.0 mm) was performed by using high-pressure balloons up to 25 atm (Fig 1). Intravenous boluses of fentanyl citrate (0.05 mg, up to a total dose of 0.15 mg) were administered if the patient experienced pain during balloon dilation. Nitroglycerin boluses of 0.25 mg were administered intraarterially into the radial artery in cases of spasm. Balloon inflation for 2–4 minutes was routinely used, and in cases of flow-limiting dissections and/or elastic recoil, inflation for up to 15 minutes was performed.
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In cases of endovascular brachytherapy, an adjunctive 6- to 8-F introducer sheath was inserted into the cephalic vein, and an uncentered bronchial catheter with a closed end (Nucletron, Veenendaal, the Netherlands) (Fig 2) or a centering balloon inflation delivery catheter (Paris; Nucletron) was then inserted. The treatment area covered the diseased segment plus margins of 1.5–2.0 cm at both ends, or to the arteriovenous anastomosis. The treatment was not extended to the radial artery. Patients were transferred to a brachytherapy suite, and a dose of 10–12 Gy to an area of 3 mm around the source center (three patients) or 12–14 Gy 2 mm deep to the vessel wall (two patients) was delivered by means of a remotely afterloaded high-dose-rate iridium 192 gamma source.
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Criteria for the Classification of Procedure Outcome
Procedure outcome was classified according to the recommendations of the Society of Cardiovascular and Interventional Radiology (8). Anatomic success for the treated lesion was defined as achievement of stenosis of less than 30% of the residual diameter. Furthermore, the procedure was defined as technically successful if residual stenosis of any of the treated lesions in the fistula did not exceed 50% and uncompromised flow was achieved. Clinical outcome, clinical events, and complications of the procedure were assessed by one nephrologist (R.I.) without knowledge of the angiographic result of the intervention. Clinical success after treatment of a thrombosed fistula was defined as resumption of normal dialysis, and clinical success after treatment of a stenosis was defined as improvement in clinical parameters (flow during dialysis, >250 mL/min).
Primary patency was defined as uninterrupted patency after intervention until the next thrombosis or reintervention. Assisted primary patency was defined as patency after the primary intervention achieved by means of repeated endovascular interventions, except thrombolysis and/or thromboaspiration. Secondary patency was defined as patency achieved by means of all repeated endovascular interventions. Complications were classified as major or minor according to criteria of the Society of Cardiovascular and Interventional Radiology (8).
Analysis of the Angiograms
Angiograms were assessed by two experienced interventional radiologists (H.I.M., E.T.K.) in a consensus reading without knowledge of the clinical outcome of the intervention. The locations of the treated lesions were classified into the following four segments: afferent radial artery, arteriovenous anastomosis, efferent antebrachial vein, and cephalic vein. The lengths of the treated lesions were measured by using an external x-ray–positive ruler. Stenoses and the caliber (normal or small) of the afferent radial artery were assessed.
Statistical Analysis
Univariate logistic regression analyses for continuous variables and the Pearson 
2 test for discrete variables were used for analyzing determinants of initial success and complications. The Kaplan-Meier method was used to calculate the cumulative patency rate versus time of follow-up for individual variables and subgroups, and the statistical difference between the survival curves was determined by means of Cox-Mantel and generalized Wilcoxon statistics (9). Variables that reached statistical significance (P < .05) were used as covariants in the stepwise Cox proportional hazards model. All statistical analyses were performed with statistical software (BMDP; University of California, Berkeley).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSION REFERENCES |
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Preinterventional angiographic findings in the fistulas and characteristics of the 169 treated lesions are shown in Table 2. In four of the eight fistulas with delay in maturation, the treated lesion was located at the anastomosis, and in four the treated lesion was located at the efferent vein (Fig 3). The endovascular techniques used in the 103 interventions are shown in Table 3. All interventions were started with brachial arterial access, but in eight cases an adjunctive retrograde cephalic venous puncture was needed for endovascular brachytherapy (n = 5) or treatment of a stenosis in a hypertrophied collateral draining vein (n = 2) or because of difficulties in traversing the occluded arteriovenous anastomosis antegradely (n = 1). Arterial spasm was registered during 38% (39 of 103) of the interventions and required intraarterial boluses of nitroglycerin in nine procedures. Endovascular brachytherapy with an uncentered catheter was performed in four interventions, and a balloon inflation centering catheter was used in one patient.
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Complications
The rate of complications was 12% (12 of 103). Minor complications included six hematomas that did not require active treatment and two pseudoaneurysms of the brachial artery that were successfully treated with ultrasonographically (US) guided compression. The rate of major complications was 4% (four of 103): two pseudoaneurysms and two cases of persistent bleeding from the puncture site (none of these interventions included pharmacomechanical thrombolysis) that required surgical treatment. Two patients with puncture site pseudoaneurysms received warfarin during the intervention. No clinical signs of pulmonary emboli were detected after the endovascular interventions.
Clinical Events during Follow-up
During follow-up (mean time, 23.2 months; median time, 16.8 months; range, 0.5–67.1 months), 14 patients received an allograft kidney, and a new Brescia-Cimino hemodialysis fistula was created in the contralateral antebrachium in two patients. No surgical revisions were performed in the failing fistulas. The 30-day mortality rate was 6% (three of 51; two patients died 5 days and one patient died 21 days after the intervention), and the total death rate during the study period was 25% (13 of 51).
Long-Term Patency
By including the initial failures, the 6-month and 1-, 2-, and 3-year primary clinical patency rates of 58% ± 7, 44% ± 8, 40% ± 8, and 32% ± 10, respectively, were obtained by means of the Kaplan-Meier analysis (Fig 4). The corresponding assisted primary patency rates were 88% ± 5, 82% ± 6, 77% ± 7, and 77% ± 7. Including the repeated interventions, 6-month and 1-, 2-, and 3-year secondary patency rates of 90% ± 5, 85% ± 5, 79% ± 7, and 79% ± 7, respectively, were registered. The primary intervention increased the functional time of the fistula a mean of 28.0 months (median time, 9.1 months). For those 20 fistulas with more than one intervention, the mean functional time of 6.1 months (median time, 3.7 months) achieved with the primary intervention was shorter than that achieved with each of the repeated interventions (mean time, 12.4 months; median time, 6.9 months; P = .02, Cox-Mantel test).
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One of the five patients who underwent endovascular brachytherapy died 5 months later with a functional fistula (Fig 2), and in two patients the fistula was clinically patent after 2- and 6-month follow-up. Two patients underwent repeated PTA 6 and 9 months after brachytherapy because of a stenotic lesion at the edge of the irradiated venous segment. To eliminate the effect of brachytherapy on the long-term results, the secondary patency rate was also calculated by stopping the follow-up time of the patients undergoing brachytherapy immediately after the intervention in which radiation therapy was administered (ie, observations after this time point were treated as censored observations in the statistical analysis). The 6-month and 1-, 2-, and 3-year secondary patency rates with this analysis were 89% ± 5, 87% ± 5, 81% ± 7, and 81% ± 7, respectively.
Among the factors that were not statistically significant determinants for clinical long-term patency after initially successful intervention, in univariate analyses, were the number of treated lesions (one vs several), the total length of the treated segments, the type of intervention (thrombolysis and/or thromboaspiration vs balloon dilation and/or stent placement only), and the duration of the functional time of the fistula before the first failure. Location of the main lesion at the arteriovenous anastomosis rather than at other segments and a small inflow artery rather than a normal-caliber inflow artery predicted a poorer long-term result (Table 4).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSION REFERENCES |
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Brachial arterial puncture offers some advantages. The puncture is usually technically straightforward, since the pulse of the hypertrophied brachial artery is strong. Injection of contrast medium antegradely to the blood flow provides superb depiction of the arterial and venous vascular tree, including the collateral veins that often develop from the fistula in cases of stenosis or occlusion in the main efferent antebrachial vein. Traversing the fistula and the diseased venous segments in the direction of the blood flow is simple: In only one early case did we encounter difficulty in finding the totally occluded arteriovenous anastomosis through the brachial arterial access, which necessitated adjunctive venous puncture. Moreover, brachial arterial access facilitates the treatment of all lesions from one puncture, including those in the cephalic vein, which is not possible from the venous access.
On the other hand, brachial arterial access can be criticized because of potential damage to the artery, which causes bleeding problems. Our rate of minor complications was 8%, and major complications were encountered in 4% of cases. Our complication rate is similar to that reported recently by Lay et al (10), who used venous access in Brescia-Cimino fistulas: The authors reported a rate of minor complications of 6.4% (two of 31) and of major complications of 3.2% (one of 31). Analysis of reports (4,12–14) of endovascular interventions in both synthetic grafts and native arteriovenous fistulas revealed total complication rates of 4%–15%.
One may also argue that manipulation of the radial artery with the guide wires and catheters may induce acceleration of athero-occlusive processes; however, we saw no evidence of that. Atherosclerotic stenoses were registered in 13 fistulas, seven of which were hemodynamically significant and in which balloon angioplasty was performed (Table 2). All these lesions were evident at the first diagnostic study, and we did not encounter any new lesions in the 50 repeated interventions. Slight arterial spasm was a common phenomenon during the antegrade intervention through the brachial artery (Fig 1), but treatment with intraarterial nitroglycerin was required in only 9% of the interventions and never hindered successful completion of the intervention.
Determinants of Initial Success and Long-term Results
Table 5 summarizes the published results of endovascular interventions in failing antebrachial Brescia-Cimino hemodialysis shunts. In these trials, there is considerable variation in the criteria used for the definition of initial success and long-term results, as well as in the endovascular techniques used. Consequently, comparison of the results is difficult. The initial success achieved in the present study is on the same order as results reported by other authors during the 1990s: the primary technical and clinical success rates are 75%–100% in the published series (5,6,10–14).
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The small patient populations in previous studies does not facilitate life-table analysis without excessive statistical uncertainty (Table 5). In the present study, the primary patency rate at 1 year was only 44%, and 20 of 53 shunts required repeated interventions. However, a majority of the originally successfully reopened fistulas were functional at 3 years; the secondary patency rate calculated by excluding initial failures was 87%. The primary patency rate of endovascular therapy in failing Brescia-Cimino shunts seems to be somewhat better than that reported in most studies of synthetic hemodialysis grafts (patency rate at 1 year, 8%–40%), whereas the secondary patency rate is similar (20). Fewer interventions are needed to attain this goal in native fistulas, but we needed a mean of 1.9 interventions per fistula to attain a 79% secondary patency rate at 3 years. Turmel-Rodrigues et al (4), however, reported the need for reintervention every 8 months to attain a 73% 3-year secondary patency rate for synthetic grafts.
Authors of previous reports (4,6,10,11) have concentrated on the treatment of lesions at the venous segments of mature Brescia-Cimino shunts. We were able to successfully treat 32 fistulas with anastomotic stenoses. Three of these shunts were recently created, and there were no occurrences of vessel rupture. Although arteriovenous anastomosis was a predictor for poorer long-term patency (Table 4), it seems evident that PTA should be the primary therapy for hemodynamically significant anastomotic stenosis, since there was no need for later surgical reconstruction in any of the anastomoses.
Although 33 interventions in our study were performed in totally occluded fistulas (Table 2), we encountered only 11 interventions with considerable amounts of visible thrombus that necessitated pharmacomechanical thrombolysis or catheter thromboaspiration during the intervention. This number of interventions is probably because of our policy of active angiographic evaluation of the shunts when hemodynamic parameters show signs of failure of the fistula (Table 1). Doppler US imaging of the shunt was routinely used during the study period in cases of uncertainty to confirm clinical suspicion of failing fistulas; focal acceleration was used to predict stenoses, thereby increasing the risk for thrombosis (21) and prompting early angiography.
Many trials have demonstrated the benefit of close hemodynamic monitoring and early treatment of hemodialysis access graft stenoses on the total life span of hemodialysis shunts (14,22) in which synthetic grafts were used, but there are few reports about native arteriovenous fistulas (4). Although pharmacomechanical thrombolysis and thromboaspiration are well-established treatments (15,23,24), it is evident that endovascular therapy of a stenotic shunt without a considerable amount of thrombus is a more straightforward and secure procedure than intervention in a shunt with a long occluded segment and extensive thrombus.
Role of Endovascular Stent Placement and Brachytherapy
Several authors (5,6,10) showed that the indications for stent placement in antebrachial venous stenoses in hemodialysis shunts should be strict because the long-term benefit in comparison with that of PTA is modest. Vorwerk et al (6) reported primary patency rates of 56%, 31%, and 14% at 6 months and 1 and 2 years, respectively, in the treatment of mainly central and upper arm venous lesions in a population with both native fistulas and synthetic graft shunts. Primary patency rates of only 47% and 20% at 6 months and 1 year, respectively, were obtained in another study (5) in a subgroup of Brescia-Cimino fistulas.
We used stent placement during the whole 5-year study period only in cases with an inadequate result after prolonged balloon dilation, and in all cases the patients previously had undergone angioplasty several times. The mean interval between endovascular interventions to maintain a functional fistula increased 1.9-fold (3.4 months increased to 6.3 months) after stent placement, a finding similar to that reported by others (5). Elective stent placement in restenosed lesions with a short recurrence interval may therefore be warranted in antebrachial veins with Brescia-Cimino fistulas (5).
Several experimental studies and preliminary clinical results show promising results of the usefulness of endovascular brachytherapy in preventing restenosis in peripheral (25) and coronary arterial (26) angioplasty and stent placement. Since the process of restenosis in hemodialysis shunts is sometimes aggressive, necessitating several balloon angioplasties and/or stent placements within short time intervals, endovascular brachytherapy also seems an attractive treatment modality in these lesions. Waksman et al (7) used endovascular brachytherapy in restenosed lesions in 18 hemodialysis grafts, and only 11 sites remained patent at a mean follow-up of 44 weeks. The authors speculated that the poor results may have resulted from poor gamma source centering within a large vessel.
We also used an uncentered catheter with a closed end for the first four patients in our study. This technique has a major theoretic weakness, since the radiation dose distribution is not uniform in the vessel wall and lesion. A centering balloon inflation catheter is now available, and it may improve the accuracy of radiation therapy.
Several unanswered questions remain regarding endovascular brachytherapy, including exact knowledge of potential target cells, the width of the therapeutic radiation dose window, and the long-term effects. Because we used endovascular brachytherapy in fewer than 5% of the interventions in our study—only in selected restenosed lesions during the last year of the study—the effect of this treatment modality on the long-term results as expressed by means of the Kaplan-Meier method is negligible. However, our preliminary experience indicates that endovascular brachytherapy with an 192Ir gamma source in antebrachial Brescia-Cimino hemodialysis shunts is feasible and seems not to have acute complications.
Our results show that endovascular interventions with antegrade brachial arterial access are feasible and highly effective in restoring the function of failing antebrachial Brescia-Cimino fistulas; with repeated interventions, the majority of shunts remain functional until the patient’s death or receipt of a transplanted kidney.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Abbreviation: PTA = percutaneous transluminal angioplasty
Author contributions: Guarantor of integrity of entire study, H.I.M; study concepts and design, R.I., H.I.M., E.T.K.; definition of intellectual content, H.I.M.; literature research, H.I.M.; clinical studies, R.I., P.M., P.K., E.L., H.I.M.; data acquisition, E.T.K., P.K.; data analysis, H.I.M.; statistical analysis, H.I.M.; manuscript preparation, H.I.M., P.M., T.L.; manuscript editing, R.I., T.L.; manuscript review, T.L.; manuscript final version approval, H.I.M., E.T.K.
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSION REFERENCES |
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represents arbitrary time points for indicating the number of cases remaining under evaluation.