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Vascular and Interventional Radiology |
1 From the Department of Angiography and Interventional Radiology, Universitatsklinik fur Radiodiagnostik, AKH Universitatskliniken, Wahringer Gurtel 18-20, A-1090 Vienna, Austria (J.L., M.C.); Department of Radiology, Division of Interventional Radiology, Stanford University, Palo Alto, Calif (M.D.D.); Antwerp Bloedvaten Centrum, Belgium (J.B.); Miami Cardiac and Vascular Institute, Fla (B.T.K., G.J.B.); Department of Vascular Surgery, Hopital De La Timone, Marseille, France (P.P.); W. L. Gore and Associates, Flagstaff, Ariz (R.A.S.). Received July 7, 1999; revision requested August 16; revision received November 29; accepted December 7. Financial support is listed at the end of this article. Address correspondence to J.L. (e-mail: Johannes.Lammer@univie.ac.at).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: A self-expanding endoprosthesis with an expanded polytetrafluoroethylene tube inside a nitinol support structure was implanted in 127 patients with symptomatic PAOD in the iliac (61 limbs) and femoral arteries (80 limbs). Clinical category status, ankle-brachial index, and color duplex flow imaging results were recorded before treatment, at discharge, and at 1, 3, 6, and 12 months after treatment. Aspirin was administered throughout the study, and heparin was administered during and for 2 days after the procedure.
RESULTS: Endoprosthesis deployment was technically successful in all patients. Complications occurred in 24 of 141 procedures and included three major complications. Early thrombosis (within 30 days) occurred in one iliac and three femoral arteries. Late restenosis or reocclusion was observed in five iliac and 14 femoral arteries within the 1st year. Primary patency rates in iliac arteries were 98% ± 3% (standard error) and 91% ± 4%, respectively, at 6 and 12 months after treatment. Primary patency rates in femoral arteries were 90% ± 3% and 79% ± 5%, respectively, at 6 and 12 months. Secondary patency rates were 95% and 93% for iliac and femoral arteries, respectively, at 12 months after treatment.
CONCLUSION: The device used in this study can be implanted without additional risks to the patient and provided encouraging patency rates up to 1 year.
Index terms: Arteriosclerosis, 92.721 , 98.721 • Arteries, peripheral • Arteries, restenosis, 92.44, 98.44 • Arteries, stenosis or obstruction, 92.44, 92.721, 98.44, 98.721 • Arteries, grafts and prostheses, 92.1286, 98.1286
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Long-term patency is dependent on several factors, such as the initial increase in luminal diameter, arterial remodeling, and intimal hyperplasia. The first two factors can be positively influenced by stents. Stents trigger an increase in the activity of intimal hyperplasia, however, and may cause recurrent stenoses. In coronary arteries, the Benestent Study Group (31) and the Stent Restenosis Study Group (32) demonstrated a reduced incidence of recurrent stenoses after placement of balloon-expandable stents. In iliac and femoropopliteal arteries, however, similar results have not been reported. The Dutch Iliac Stent Trial Group (23) used color duplex ultrasonography (US) to demonstrate 2-year patency rates of 71% in patients who underwent stent placement alone versus 70% in those who underwent PTA plus stent placement. In a meta-analysis in which the results of aortoiliac PTA were compared with those of stent placement, Bosch and Hunink (29) found a 4-year primary patency rate, excluding technical failures, of 68% for PTA versus 77% for stent placement in patients with claudication. In a randomized study to compare femoropopliteal PTA and Palmaz stent placement (33), the 1-year primary patency rate was 64% for PTA versus 62% for stent placement.
A stent-graft consists of a metallic stent with a biologically compatible polymer cover usually made of polyester or polytetrafluoroethylene. The purpose of the polymer cover is to prevent or limit myointimal ingrowth along the length of the treated segment and thereby improve patency, as compared with the patency achieved with conventional angioplasty and stent placement.
The purpose of this prospective multicenter study was to investigate the safety and efficacy of the HEMOBAHN Endoprosthesis (W. L. Gore and Associates, Flagstaff, Ariz), a flexible, self-expanding, endoluminal prosthesis for treatment of peripheral arterial obstruction.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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The inclusion criteria were as follows: documented atherosclerotic stenotic or occlusive lesions that caused either lifestyle-altering claudication (Rutherford-Becker category 1–3) or chronic, critical, lower-limb ischemia (Rutherford-Becker category 4 or 5); lesions in either an iliac and/or a femoral artery; and a lesion length of 3–20 cm. Patients were excluded if they had renal failure (creatinine level > 2.0 mg/dL [177 µmol/L]); severe, sustained hypertension (systolic blood pressure > 160 mm Hg); poor distal runoff (one or no distal runoff vessel); and presence of a persistent residual 30% stenosis after predeployment balloon angioplasty (which would have been performed because of potential difficulty in deploying the device in a relatvely narrow lumen). A total of 127 patients (83 men, 44 women) with a mean age of 65 years (range, 37–89 years) were enrolled in this multicenter clinical study from September 1996 to February 1998.
Device Description
The HEMOBAHN Endoprosthesis is a flexible, self-expanding, endoluminal prosthesis. The two principle components of the device are an expanded polytetrafluoroethylene (ePTFE) tube inside a nitinol sinusoidally shaped helically wrapped stent. The tube is composed of thin-walled radially reinforced ePTFE with a wall thickness of approximately 0.1 mm and pore diameter of about 30 µm (pore density = 0.45 g/cm3, or 80% air by volume). The external supporting structure of the graft consists of a single strand of nitinol wire formed into a sinusodal shape that is wound in a helical fashion around the tube. The nitinol wire structure is secured to the ePTFE tube by means of fluorinated ethylene propylene and ePTFE tape. The nitinol supporting structure is located along the entire external surface of the ePTFE tube. The diameter of the nitinol wire ranges from 0.152 mm in a 6-mm-diameter device to 0.229 mm in a 13-mm-diameter device. Therefore, the resistance against external compression ("hoop strength" or radial strength) is different for the various device diameters. For the 6-mm device, for example, the radial strength is 317–766 N/cm. The prosthesis does not shorten during expansion.
The prosthesis is available in a variety of diameters and lengths. Selection of an appropriately sized prosthesis is based on the diameter and nature of the vessel segment to be treated and the length of the target lesion(s). The endoprosthesis is available in labeled diameters of 6 mm for 4.8–5.5-mm-diameter vessels, 7 mm for 5.6–6.5-mm-diameter vessels, 8 mm for 6.6–7.5-mm-diameter vessels, 9 mm for 7.6–8.5-mm-diameter vessels, 10 mm for 8.6–9.5-mm-diameter vessels, 11 mm for 9.6–10.5-mm-diameter vessels, and 13 mm for 10.6–12.0-mm-diameter vessels and in lengths of 5, 10, and 15 cm. Recommended introducer sheath sizes for the device range from 8 F for the 6-mm prosthesis to 12 F for the 13-mm device (Table 1).
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The procedure was initiated with standard transfemoral angiography to document the obstructive lesion and peripheral run-off vessels. For accurate measurement of vessel size, a graduated sizing catheter was used as an internal calibration reference. Standard PTA was performed after intraarterial administration of 5,000 U of heparin (to achieve an activated clotting time of longer than 250 seconds). The success of PTA was determined at angiography, and the percentage of residual stenosis was ascertained by using the stenosis-grading software (if available) of the digital subtraction angiography (DSA) unit.
The device was inserted over a 0.025-inch or smaller guide wire through an 8–12-F introducer sheath (sheath diameter was dependent on prosthesis diameter). The prosthesis was flexible enough to be used for treatment of contralateral lesions by using a crossover technique. For treatment of obstructions, the endoprosthesis should extend into a portion of healthy vessel by at least 1 cm proximal and distal to the margins of the lesion. Once in position, the device was deployed by unscrewing the deployment hub on the catheter and pulling the deployment line. Deployment of the prosthesis occurs from the trailing end of the catheter toward the leading end (catheter tip). The prosthesis does not shorten as it deploys. After device deployment, the delivery catheter was removed, and balloon angioplasty was performed within the lumen of the prosthesis to dilate residual narrowing and achieve optimal contact with the arterial wall. The balloon selected for postdeployment PTA should ideally have the same diameter as the prosthesis, to fully expand the device and seat it to the vessel wall. An angiogram of the treated segment and peripheral run-off vessels was obtained prior to completion of treatment. Heparin administration was maintained for up to 48 hours, according to standard practice (activated partial thromboplastin time of 1.5 times the normal value), if indicated. Antiplatelet therapy with acetylsalicylic acid was maintained at appropriate dosages throughout the course of the study.
Follow-up Examinations
Clinical assessment, treadmill testing, and resting ankle-brachial index measurements were performed before discharge and at 1, 3, 6, and 12 months. Functional results were categorized according to a standard limb ischemia score (34,35). Color duplex flow US of the treated limb was performed at each visit to determine the presence of flow through the treated area.
Definition of Success and End Points
Treatment safety was defined by recording device-related and treatment-related adverse events. Major adverse events were defined as those necessitating an increased level of care (ie, treatment in the intensive care unit), surgery, prolonged hospital stay, or death.
The efficacy of the treatment was defined by recording patency up to 12 months after implantation of the prosthesis. Hemodynamic success was defined as improvement of 0.10 or more or deterioration from the first postprocedural measurement of no more than 0.15 in the resting ankle-brachial index. The device was deemed patent if flow was present and if the peak systolic velocity ratio was less than 2.5 at the time of color duplex flow US.
Clinical effectiveness was determined by using the chronic limb ischemia categories proposed by the Society of Vascular Surgery and the International Society of Cardiovascular Surgery (34,35). Limb ischemia categories were scored from grade 0 for asymptomatic to grade 6 for major tissue loss with a functional foot that can no longer be salvaged. Clinical effectiveness was defined as improvement by at least one clinical category level over the pretreatment level.
The primary end points of the study were based on assessment of complications and primary and secondary patency as determined with color duplex flow US. Secondary end points included functional parameters such as the ankle-brachial index and clinical status. The Clinical Status Scale (35) is a functional grading scale from -3 (markedly worse) to 0 (baseline) to +3 markedly better.
Statistical Analyses
Goals for 1-year primary patency were set according to where the device was deployed. If the device was deployed in a femoral artery, the goal of 75% primary patency at 1 year was set; for the iliac artery, the goal of 85% primary patency at 1 year was set. To improve confidence in this estimate, a further condition was set: The standard error of the estimate of 1-year primary patency was required to be less than 0.05 for prostheses implanted in either the femoral or iliac arteries. Therefore, to estimate primary patency with the required precision, a sample size of 80 subjects was necessary for the femoral application, and a sample size of 60 was necessary for the iliac application.
Data were analyzed according to the intention-to-treat principle. Discrete variables are expressed as counts and percentages, and continuous data are expressed as means and SDs. The arterial patency rates based on color duplex flow US results were calculated with actuarial (life-table) analysis and were expressed as a survival (patency) probability percentages with a survival standard error and 95% CIs. Life-table calculations were performed by using SAS software (SAS Institute, Cary, NC).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Pretreatment risk factors among the patients, such as hypertension, coronary arterial disease, hyperlipidemia, and diabetes, are listed in Table 2. Pretreatment chronic limb ischemia categories for the 53 patients in the iliac arterial treatment group were as follows: no patients with grade 0, five with grade 1, 22 with grade 2, 21 with grade 3, two with grade 4, three with grade 5. Pretreatment grades for the 74 patients in the femoral arterial treatment group were as follows: one with grade 0, five with grade 1, 25 with grade 2, 34 with grade 3, three with grade 4, and six with grade 5 (Fig 3a, 3b).
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In the femoral arterial treatment group, nine (11%) of 80 lesions were category A obstructions, 49 (61%) were category B, and 22 (28%) were category C. Fifty (62%) of the lesions were considered to represent diffuse disease longer than 10 cm or occlusions. The mean length of devices used in the femoral treatment group was 13.1 cm (range, 5–40 cm), and the mean diameter of the devices was 6.3 mm (range, 6–7 mm).
In the iliac arterial treatment group, a total of 72 devices were implanted, and the mean length of the treated segments was 6.9 cm. Two devices were placed in 11 limbs, and three devices were placed in one limb. The mean length of the treated segments in the 12 limbs with multiple devices was 11.7 cm. In the femoral arterial treatment group, 103 devices were deployed, and the mean length of the treated segments was 13.1 cm. Two devices were placed in 11 limbs, and three to five devices were placed in four limbs. The mean length of the treated segments in the 15 limbs with multiple devices was 25.7 cm.
Primary technical success, with correct placement and antegrade flow through the prosthesis, was achieved in all patients (Figs 4 –7). In one case, an 8-mm-diameter device could not be advanced across the lesion; the device was therefore removed, and a 7-mm prosthesis was successfully placed.
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Dissections occurred during angioplasty before device placement in two iliac and four femoral arteries. In four arteries, the dissections were covered by the prosthesis. In one case (after open surgical access to the femoral artery), the angioplasty-related dissection proximal to the deployed device was treated by means of endarterectomy and surgical-patch plasty. In another patient, dissection occurred during sheath insertion after open surgical access. This dissection had to be treated surgically, and the adverse event was counted as a major complication. In one patient, an dilation of a too-large balloon within the distal end of the prosthesis caused rupture of the uncovered vessel. This was treated successfully by placing a second overlapping device.
Complications at the access site consisted of minor hematomas in three patients (two after antegrade punctures) and wound infections in two patients (both after arteriotomy). In one of the cases of infection, débridement, sartorious muscle flap rotation, and antibiotics were necessary (major complication).
Knee hydrarthrosis was observed once and treated with injection of cortisone drugs; the relationship between this complication and the device remained unclear. One patient was diagnosed with amyotrophic lateral sclerosis. Although this was classified as a major adverse event during the trial, this complication probably was not related to the device. None of the complications necessitated conversion to open surgical revascularization. No device- or procedure-related deaths were reported during the study. During follow-up, four patients died of other causes (acute pulmonary edema, stroke, heart attack, and sepsis).
Patient follow-up at 1 year after treatment was performed in 50 (94%) patients in the iliac treatment group and in 67 (91%) patients in the femoral treatment group. Ten patients (three in the iliac group and seven in the femoral group) were lost to follow-up during the course of the study.
At 1 year after treatment, chronic limb ischemia grades were reported for 46 patients in the iliac treatment group, as follows: 29 with grade 0 ischemia, seven with grade 1, seven with grade 2, three with grade 3, and none with grades 4–6 (Fig 3a). In addition, Clinical Status Scale scores at 1 year after treatment were reported for 44 patients in the iliac treatment group: One patient showed a mild decline (score, -1), four showed no change or minimal improvement (score, 0 or +1), 10 showed moderate improvement (score, +2), and 29 showed marked improvement (score, +3).
At 1 year after treatment, limb ischemia grades for the femoral group were reported for 55 patients: 45 with grade 0 ischemia, seven with grade 1, one with grade 2, one with grade 3, none with grade 4, and one with grades 5 and 6 (Fig 3b). In the femoral group, Clinical Status Scale scores were reported for 51 patients at 1 year after treatment: Two patients showed a minimal decline or no change (score, -1 or 0), seven showed minimal or moderate improvement (score, +1 or +2), and 42 showed marked improvement (score, +3).
In the iliac group, the mean ankle-brachial indexes were 0.59 before treatment and 0.92, 0.91, 0.93, and 0.85 at 1, 3, 6, and 12 months after treatment, respectively. In the femoral group, the mean ankle-brachial indexes were 0.60 before treatment and 0.97, 0.92, 0.96, and 0.94 at 1, 3, 6, and 12 months after treatment, respectively. Although posttreatment scores represented only those patients in whom data were reported at a point in time and cannot be analyzed statistically, these scores demonstrate a strong trend toward improved function after device placement.
During follow-up, early occlusion of the prosthesis (within 30 days) occurred in four limbs, once in the iliac treatment group and three times in the femoral treatment group. Late occlusions (30 days to 12 months) occurred in an additional five limbs in the iliac group and in 14 limbs in the femoral group. The length of the stenosed or occluded device in the iliac arterial treatment group was 5 cm in four patients, 10 cm in one, and 15 cm in one. In the femoral treatment group, stenosis or occlusion occurred in one 5-cm-long device, 10 10-cm-long devices, and six 15-cm or longer devices (these included cases of multiple devices in a single artery). The obstructed devices were treated with PTA (with or without additional fibrinolysis) in 15 patients, with thrombectomy in one, and with bypass surgery in six. One patient remained untreated.
In the iliac arterial treatment group, the primary patency rate (based on color duplex flow US findings and calculated with life-table analysis) was 98% ± 3% at 6 months after treatment (at the start of the 180–210-day follow-up interval) and 91% ± 4% at 12 months after treatment (at the start of the 360–390-day follow-up interval). In the femoral arterial treatment group, the primary patency rates were 90% ± 3% at 6 months after treatment and 79% ± 5% at 12 months. The secondary patency rates were 98% at 6 months and 95% at 12 months for the iliac treatment group and 96% at 6 months and 93% at 12 months for the femoral treatment group (Tables 4, 5; Figs 8, 9).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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The use of stent-grafts for the treatment of peripheral arterial occlusive disease is of particular interest because of the considerable incidence of restenosis after PTA. These restenoses are caused by residual obstructive plaque or constrictive remodeling and intimal hyperplasia. In iliac arteries, the 1-year primary patency rate after PTA ranges has been reported (1–4,29) to be between 67% and 92% (weighted mean, 78%). In long diffuse lesions involving the external iliac artery (American Heart Association categories 2 and 3), however, the 1-year patency rate may be as low as 67%–74% (4). Stent placement has improved midterm patency rates by enhancing the initial technical success rate and reducing delayed remodeling. The reported (14–21, 23,29) 1-year primary patency rate after iliac artery stent placement is 78%–97% (weighted mean, 90%).
The theoretic benefit of stent-grafts is manifold. Like bare stents, stent-grafts may help improve the technical success rate by fixing obstructive flaps and dissections, by preventing elastic recoil, and by permanently compressing plaque. In the long term, the stent structure may prevent remodeling, and the fabric tube may prevent tissue infiltration and intimal hyperplasia. Limited research (47–52) has been conducted to test these hypotheses and to evaluate tissue response to the presence of endovascular stent-grafts. Healing associated with surgically placed ePTFE grafts progresses from the anastomotic region toward the center of the graft. In grafts 7–9 cm long, healing is 60% complete at 12 months (47). Pore size affects the healing mechanism: As pore size increases, both polyester and ePTFE graft materials can heal by allowing transmural migration of cells. Thus, a pore size of 6–90 µm was claimed to be optimal for promotion of graft healing (48). Dolmatch et al (49) studied the tissue response to ePTFE-covered Palmaz stents in a dog model. They compared two stent-grafts with ePTFE graft material that covered either the luminal or abluminal surface of Palmaz stents; a bare stent served as the control stent. Dolmatch et al reported patency rates to be highest in the bare stent control group and intimal thickness to be greatest in the stent-graft group when the graft material was on the luminal surface of the stent. Because the ePTFE material was sutured only at the ends of the stent, it is possible that movement of the graft material accounted for the neointimal thickening and poor patency. In a study of tissue healing associated with stent-grafts in a sheep model, we found that a prosthesis with a luminal ePTFE graft showed less intimal hyperplasia than a device with an abluminal graft (Cejna M, unpublished results, 1999). Virmani et al (50) found that nitinol stents with an ePTFE inner lining (a 4.5-cm-long prototype of the stent used in the present study) that were placed in the iliofemoral arteries of adult greyhound dogs remain patent up to 1 year and show almost complete endothelialization of the flow surfaces after 3 months. In addition, neointimal formation peaked at 3 months and then progressively decreased. Virmani et al speculated that the very thin ePTFE material may have allowed graft endothelialization to occur by means of transgraft migration of endothelial cells. They also suggested that the self-expanding nature of the device limited medial injury and thereby limited proliferation of smooth muscle cells.
The healing associated with graft materials is known to be less extensive in humans. Marin et al (51,52) studied the development of intimal hyperplasia and healing associated with stent-grafts in humans and found endothelium at a distance of 1–3 cm from the ends of the stent-grafts at 3 months and 8 cm from the ends at 5 months. However, there also was tissue ingrowth through the grafts. Thus, experimental studies have provided limited evidence that stent-grafts may undergo re-endothelialization and reduce the amount of intimal hyperplasia.
The present multicenter clinical study of a self-expanding nitinol endoluminal prosthesis with an ePTFE flow surface for the treatment of symptomatic peripheral arterial occlusive disease was designed to evaluate complications, device-related mechanical problems, and initial device effectiveness (patency up to 1 year). Placement within the predilated obstruction was technically successful in all 141 lesions. The flexibility of the catheter-mounted prosthesis permitted insertion through tortuous vessels and allowed for retrograde placement of the device with the use of a crossover technique. This is an advantage over other designs in which the stent-graft must be pushed through an introducer sheath, and the prosthesis is not flexible enough to cross the aortic bifurcation. Initial technical failures, such as breakage of the deployment line and friction at the distal olive during withdrawal, were corrected during the early part of the trial. The spiral folding of the endoprosthesis around the delivery catheter may lead to incomplete opening in a tight lesion. Therefore sufficient predilation is mandatory before placement of the device.
Complications were observed in 17.0% of the procedures; however, major complications were seen in only 2.1% of the cases. Reported rates of major complications after iliac arterial PTA versus iliac arterial stent placement are 2.3%–4.4% versus 1.0%–10.8%, and the reported rates after femoropopliteal PTA versus stent placement are 2.4%–6.3% versus 1%–17% (2–4,9–16,18–21,53). However, it must be mentioned that increased experience with and use of smaller introducer systems for PTA and stent placement have led to reductions in the complication rates in the more recent reports. Wound infections in two patients were seen only after surgical cutdown, which is not the most commonly used procedure because the prosthesis can be inserted percutaneously. Antibiotic treatment was not delivered during implantation of the endoprosthesis. Despite the larger introducer system for femoropopliteal (8–9 F) and for iliac (9–12 F) devices, important hematomas were observed in only three (2.4%) patients. Distal embolization after recanalization of total occlusions occurred in four limbs (2.8%); thus, it is not known whether the emboli were attributable to the recanalization and PTA or to the use of the device. Dissections after PTA were documented and covered by means of subsequent placement of the prosthesis. Finally, device-related minor complications in seven patients, such as problems with the delivery catheter, guide wire, and deployment line, were technically solved during the early part of the study. Thus, use of the endoprosthesis in peripheral arterial obstructions (stenoses and occlusions) did not lead to an increased complication rate over that previously reported for procedures for peripheral arterial occlusive disease. Henry et al (54) reported major complications in 15 (14%) of 105 patients after implantation of polyester-covered stent-grafts (Cragg EndoPro System 1; Minimally Invasive Technologies, La Ciotat, France [no longer available]) in peripheral arteries. In addition, Henry et al observed fever and local pain in 27 (26%) patients. Such symptoms, which were also observed by other groups (55,56) using the EndoPro System 1 device, were not observed in the current study.
Early thrombosis is a potential problem of implants. Antithrombotic therapy (aspirin and heparin) was used to prevent early thrombosis in the present study. Early thrombosis, defined as thrombosis within 30 days, occurred in four (2.8%) limbs, including one iliac segment and three femoral segments. In comparison, in the series of Henry et al (54), eight (7.6%) of 105 polyester-covered stent-grafts led to thrombosis within 30 days, including one in an iliac segment and seven in femoropopliteal segments, despite administration of low-molecular-weight heparin, ticlopidine hydrochloride, and aspirin as antithrombotic medications. Maynar et al (56) reported five cases of thrombosis in 11 patients after implantation of the EndoPro System 1 stent-graft in a superficial femoral artery. After coronary arterial stent placement, it has been demonstrated that more aggressive platelet inhibition therapy, which blocks different pathways of platelet activation, may reduce the rate of early thrombosis (57). The use of a glycoprotein IIb/IIIa–receptor antagonist, as well as prolonged anticoagulation with low-molecular-weight heparin, may further reduce the thrombosis rate (58,59). Early failures (within the 1st month) have also been observed after PTA. In his analyses, Johnston (4,10) reported early reobstruction rates of 4% and 9% after PTA of iliac arterial stenoses and occlusions, respectively, and 11% after PTA of femoropopliteal obstructions.
Late reobstruction of the endoprosthesis used in the present study was observed in five cases of iliac arterial and 14 cases of femoral arterial implantation. Thus, the primary patency rates, determined on the basis of color duplex flow US results in iliac arterial implants, was 91% at 1 year after treatment for both stenoses and occlusions (mean length of treated segment, 6.9 cm); the secondary patency rate was 95%. These results compare well with the 1-year patency rate of 98% for polyester-covered stent-grafts as reported by Henry et al (54) and with the reported (14–22,29,53) 1-year patency rates for iliac arterial stents, which range between 78% and 97% for stenoses and 68% and 94% for occlusions. The 1-year primary patency rates after PTA alone seem to be less, however: 67%–92% for stenoses and 60%–94% for occlusions (1–8,29). Of course, it would be valuable to determine the particular clinical or morphologic characteristics of iliac arterial obstructions in which stent-grafts might be beneficial. However, this question cannot be answered in the present study.
In the femoral arterial treatment group, the primary patency rate of the device, measured with color duplex flow US, was 79% at 1 year after treatment for both stenoses and occlusions; the secondary patency rate was 93%. It is interesting to note that the mean device length used in cases of femoral arterial obstruction was 13.1 cm, which would be a type C lesion according to the Society of Vascular Surgery and the International Society of Cardiovascular Surgery criteria or a category 3 lesion according to the American Heart Association criteria, both of which types are associated with generally poor long-term prognoses after PTA. Matsi et al (11) reported a 1-year primary patency rate of 47% after PTA for femoropopliteal arterial obstructions (both stenoses and occlusions) in patients with claudication (140 limbs). The secondary patency rate was 63% at 1 year. They also found a statistically significant difference in patency rates that was dependent on the length of the lesion. When lesion length is less than 15 cm, the primary patency rate at 1 year is 56%, but when longer than 15 cm, the primary patency rate at 1 year is 23%. Murray et al (60) reported initial patency rates of 23% at 6 months for PTA-treated femoropopliteal stenoses longer than 7 cm. In a separate study of long (>10-cm) femoropopliteal stenoses and occlusions in patients with severe claudication, Murray et al (12) reported a cumulative primary patency rate after PTA of 69% at a mean long-term follow-up of 18 months (range, 12–24 months). Thus, it appears that the endoprosthesis used in the present study has the potential to increase the long-term patency after recanalization of long femoropopliteal arterial obstructions. A randomized trial to compare PTA and the HEMOBAHN Endoprosthesis in superficial femoral arterial obstructions is in progress in the United States.
The design of an appropriate stent-graft for endoluminal treatment of obstructive arterial lesions is a complex problem. A critical issue in endoluminal stent-grafts is early thrombogenicity, which may be mitigated by newer more effective antithrombotic agents. Delayed reocclusions may be caused by intimal hyperplasia at the proximal or distal end of the stent-graft, due to compliance mismatch if the stent-graft is too stiff or to myointimal ingrowth through the fabric if the pore size is too large. Re-endothelialization also is important to prevent delayed rethrombosis.
Various modes of reducing recurrent stenoses are currently under investigation. Local drug delivery or local gene therapy are in an early preclinical testing stage. Endoluminal radiation therapy and endoluminal bypass with stent-grafts are in the early clinical feasibility evaluation stage. The results of the present multicenter clinical study of an ePTFE-nitinol endoprosthesis showed that the device could be implanted without additional risks to the patient and provided encouraging patency rates up to 1 year.
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FOOTNOTES |
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Author contributions: Guarantors of integrity of entire study, J.L., R.A.S. Study concepts and design and definition of intellectual content, R.A.S., J.L., M.D.D., B.T.K.; literature research, J.L., M.C.; clinical studies, J.L., M.D.D., J.B., B.T.K., P.P., M.C., G.J.B.; data acquisition, J.L., M.D.D., J.B., B.T.K., P.P., M.C.; data analysis, J.L., R.A.S.; statistical analysis, R.A.S., M.C.; manuscript preparation, J.L.; manuscript editing, J.L., M.D.D., M.C.; manuscript review, M.D.D., B.T.K., R.A.S.
Participating Investigators and University Hospitals: J. D. Blankensteijn, MD: Academisches Ziekenhuis Utrecht, the Netherlands; J. M. Cardon, MD: Clinique Les Franciscaines, Nimes, France; J. M. Fichelle, MD: Clinique De La Defense, Nantarre, France; G. Hagmüller, MD: Wilhelminenspital, Vienna, Austria; F. F. Joffre, MD: Hopital De Rangueil, Toulouse, France; H. Müller-Wiefel, MD: St Johannes Hospital, Duisburg, Germany; U. Nyman, MD: Universitetssjukhuset, Malmø, Sweden; D. Raithel, MD: Klinikum Stadt Nürnberg, Germany; G. A. Sicard, MD: Washington University School of Medicine, St Louis, Mo; D. Vorwerk, MD: Medinzinische Einrichtungen der RWTH Aachen, Germany; C. Zollikofer, MD: Kantonspital Winterthur, Switzerland; J. P. Fichere, MD: Clinique Sainte Marthe, Dijon, France.
Funding/Support: This study was supported by W. L. Gore and Associates, Flagstaff, Ariz.
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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  T. Zeller Current state of endovascular treatment of femoro-popliteal artery disease Vascular Medicine, August 1, 2007; 12(3): 223 - 234. [Abstract] [PDF]
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 H. H. Dosluoglu, L. M. Harris, and G. S. Cherr Recanalization of Concomitant Iliac Artery and Common Femoral Artery Occlusions Using an Antegrade Hybrid (Open/Endovascular) Approach Vascular and Endovascular Surgery, April 1, 2007; 41(2): 130 - 134. [Abstract] [PDF]
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 C. Klonaris, A. Katsargyris, A. Giannopoulos, and E. Bastounis Advances in Endovascular Treatment of Femoropopliteal Arterial Occlusive Disease Perspectives in Vascular Surgery and Endovascular Therapy, December 1, 2006; 18(4): 329 - 341. [Abstract] [PDF]
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 V. J. Yacyshyn, M. R. Thatipelli, R. J. Lennon, K. R. Bailey, A. W. Stanson, D. R. Holmes Jr, and P. Gloviczki Predictors of Failure of Endovascular Therapy for Peripheral Arterial Disease Angiology, August 1, 2006; 57(4): 403 - 417. [Abstract] [PDF]
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 R. Bonvini, I. Baumgartner, D. D. Do, M. Alerci, J.-M. Segatto, P. Tutta, K. Jager, M. Aschwanden, E. Schneider, B. Amann-Vesti, et al. Late acute thrombotic occlusion after endovascular brachytherapy and stenting of femoropopliteal arteries J. Am. Coll. Cardiol., February 5, 2003; 41(3): 409 - 412. [Abstract] [Full Text] [PDF]
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 K. Schurmann, A. Mahnken, J. Meyer, P. Haage, K. Chalabi, I. Peters, R. W. Gunther, and D. Vorwerk Long-term Results 10 Years after Iliac Arterial Stent Placement Radiology, September 1, 2002; 224(3): 731 - 738. [Abstract] [Full Text] [PDF]
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 A. Odurny Radiological Investigation and Treatment of the Critically Ischemic Limb--A Review International Journal of Lower Extremity Wounds, March 1, 2002; 1(1): 33 - 42. [Abstract] [PDF]
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A. Bostrdm, S. Karacagil, A.-M. Lofberg, C. Ljungman, R. Nyman, K. Logason, and A. Hellberg Selection of Patients with Lower Limb Arterial Occlusive Disease for Endovascular Treatment of the Iliac Arteries with Duplex Scanning Vascular and Endovascular Surgery, November 1, 2001; 35(6): 437 - 442. [Abstract] [PDF]
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