Intravascular Stent Placement Research Articles

Intermediate follow‐up following intravascular stenting for treatment of coarctation of the aorta

We report a multiinstitutional study on intermediate-term outcome of intravascular stenting for treatment of coarctation of the aorta using integrated arch imaging (IAI) techniques. Medical records of 578 patients from 17 institutions were reviewed. A total of 588 procedures were performed between May 1989 and Aug 2005. About 27% (160/588) procedures were followed up by further IAI of their aorta (MRI/CT/repeat cardiac catheterization) after initial stent procedures. Abnormal imaging studies included: the presence of dissection or aneurysm formation, stent fracture, or the presence of reobstruction within the stent (instent restenosis or significant intimal build-up within the stent). Forty-one abnormal imaging studies were reported in the intermediate follow-up at median 12 months (0.5-92 months). Smaller postintervention of the aorta (CoA) diameter and an increased persistent systolic pressure gradient were associated with encountering abnormal follow-up imaging studies. Aortic wall abnormalities included dissections (n = 5) and aneurysm (n = 13). The risk of encountering aortic wall abnormalities increased with larger percent increase in CoA diameter poststent implant, increasing balloon/coarc ratio, and performing prestent angioplasty. Stent restenosis was observed in 5/6 parts encountering stent fracture and neointimal buildup (n = 16). Small CoA diameter poststent implant and increased poststent residual pressure gradient increased the likelihood of encountering instent restenosis at intermediate follow-up. Abnormalities were observed at intermediate follow-up following IS placement for treatment of native and recurrent coarctation of the aorta. Not exceeding a balloon:coarctation ratio of 3.5 and avoidance of prestent angioplasty decreased the likelihood of encountering an abnormal follow-up imaging study in patients undergoing intravascular stent placement for the treatment of coarctation of the aorta. We recommend IAI for all patients undergoing IS placement for treatment of CoA.

Right ventricular outflow tract and pulmonary artery stents in children under 18 months of age

To report our experience on patients less than 18 months of age in whom stents were placed either in the right ventricular outflow tract (RVOT) or pulmonary arteries. Although percutaneous placement of intravascular stents in congenital heart disease is common practice, there are few reports regarding placement in young children. Retrospective review of our database identified 19 patients less than 18 months of age who underwent placement of 26 stents in either the RVOT or pulmonary arteries. Data evaluated were patient age, gender, weight, site of narrowing, type of stent, gradient across the area of narrowing pre- and post-stent placement, vessel size pre- and post-stent placement, gradient, and vessel size on followup, and ability to redilate the stent if necessary. Mean patient age was 9.7 months (range 0.5-17.5 months). There were 14 males and 5 females with a mean weight of 7.1 kg (range 2.3-10.2 kg). Five patients had stents placed in the RVOT and 14 patients had 21 stents placed in the branch pulmonary arteries. Two Johnson and Johnson P188 stents were used, 23 premounted Genesis biliary stents and 1 other. Gradient across the stenotic area decreased from a mean of 52.9 mm Hg (range 20-80 mm Hg) to 15 mm Hg (range 3-40 mm Hg) (P<.001). Percutaneous placement of intravascular stents in young children is a viable procedure, can provide excellent relief of stenoses, and increases vessel size in the short term. Although many of these stents cannot be dilated to adult size, their efficacy in small infants and children in whom further surgery will ultimately be required makes them desirable for this group of patients.

Transcatheter intravascular stent placement to relieve supravalvular pulmonic stenosis

Valvular pulmonic stenosis has been successfully treated in dogs via minimally invasive transcatheter balloon dilation procedures for almost 20 years. Supravalvular pulmonic stenosis however is not amenable to balloon dilation procedures. Although several surgical procedures are described for treatment of pulmonic stenosis, the morbidity and mortality of these procedures are significantly higher than for transcatheter approaches. Two cases of supravalvular pulmonic stenosis are presented, one acquired and one congenital, which were successfully treated with transcatheter intravascular stent placement. The procedure alleviated the stenotic lesion and resolved clinical signs.

Applications of Intravascular Ultrasound in the Treatment of Peripheral Occlusive Disease

Intravascular ultrasound (IVUS) has emerged as a useful and often necessary adjunct in a rising number of catheter-based peripheral interventions. IVUS catheters enable luminal and transmural cross-sectional imaging of peripheral vessels with high dimensional accuracy and provide detailed information about lesion morphology. IVUS is able to guide the optimal choice of appropriate angioplasty technique, guide the delivery of endovascular devices, and assess the immediate outcome of an intervention. In this review we discuss the role of IVUS for peripheral occlusive diseases, specifically the application of IVUS technology during percutaneous transluminal angioplasty (PTA), intravascular stent placement, crossing total occlusions, and venous obstructive disease.

Endovascular Treatment of Spontaneous Isolated Dissecting Aneurysm of the Superior Mesenteric Artery Using Stent-Assisted Coil Embolization

Spontaneous isolated dissecting aneurysm of the main trunk of the superior mesenteric artery is a rare condition. We treated a patient with this condition successfully by stent-assisted coil embolization. Intravascular stent placement may widen the indications for endovascular coiling of the aneurysmal false lumen to avoid perforation.

Stent placement for the treatment of nonsaccular aneurysms of the vertebrobasilar system

Vertebrobasilar nonsaccular aneurysms represent a small subset of intracranial aneurysms and usually are among the most challenging to be treated. The aim of this article was to review the literature and summarize the experience in the treatment of these lesions with endovascular approaches. The method of stent implantation as it is performed at the authors' institution, including options available for vertebral artery access, is described. Practitioners involved in the treatment of these lesions should be aware of the potential application of intravascular stent placement as well as the associated postprocedure risks and potential complications.

The changing roles of radiologists, cardiologists, and vascular surgeons in percutaneous peripheral arterial interventions during a recent five-year interval

This study aimed to determine the relative roles of radiologists, cardiologists, vascular surgeons, and other physicians in performing percutaneous peripheral arterial interventions and how these roles have changed over a recent 5-year period. The authors reviewed the Medicare Part B fee-for-service databases between 1997 and 2002 for the Current Procedural Terminology (4th ed.) (CPT-4) surgical procedure codes for percutaneous transluminal angioplasty (PTA) of noncardiac peripheral arteries (six codes), the transcatheter placement of noncardiac intravascular stents (two codes), and endovascular aortic stent graft placement (six codes). Using the Medicare physician specialty codes, procedure volume in each CPT-4 code was determined for radiologists, cardiologists, vascular surgeons, and other physicians. Percentage changes from 1997 to 2002 were calculated for PTA and intravascular stent placement procedures. Between 1997 and 2002, the total Medicare procedure volume in the eight procedure codes relating to PTA and stent placement increased by 95%. In 2002, radiologists performed 72,657 of these procedures, cardiologists 62,901, vascular surgeons 17,895, and other physicians 19,666. Over the 5-year interval, procedure volume among radiologists increased 29%, among cardiologists by 181%, among vascular surgeons by 398%, and among other physicians by 195%. Radiologists' share in the total pool of procedures in 2002 was 42.0% (down from 63.3% in 1997), cardiologists' 36.3% (up from 25.2% in 1997), vascular surgeons' 10.3% (up from 4.0% in 1997), and other physicians' 11.4% (up from 7.5% in 1997). Trend data were not available for endovascular aortic stent graft procedures. Between 1997 and 2002, procedure volume in percutaneous peripheral arterial interventions grew at faster rates among cardiologists, vascular surgeons, and other physicians than it did among radiologists. As a result, radiologists' share of this market declined during the interval. However, procedure volume among radiologists continued to grow over the 5 years, and in 2002, they still had the largest share among the four physician specialty groups. Thus, despite the erosion, interventional radiologists still maintain a strong position in this rapidly growing field.

Distal septic emboli and fatal brachiocephalic artery mycotic pseudoaneurysm as a complication of stenting

The use of percutaneous angioplasty with subsequent intravascular metallic stent placement has gained increasing acceptance over the past decade. Infections of these stents appear to be uncommon; however, the rarity of this complication may in part be the result of a lack of availability of long-term follow-up data. A number of examples of infected cardiac and peripheral vascular stents have been reported, often with fatal consequences. Herein, we report a 74-year-old woman who underwent subclavian and brachiocephalic artery angioplasty and stent placement for symptomatic stenoses. Six months after the initial intervention, the patient returned with restenosis of the stents and underwent repeat angioplasty to restore full patency. Two weeks later, the patient was readmitted with generalized malaise and multiple erythematous, macular lesions on the right forearm and hand. Blood cultures grew Staphylococcus aureus, and a computed tomographic scan of the chest showed a large brachiocephalic artery pseudoaneurysm with surrounding hematoma. Despite prompt surgical intervention, this complication proved ultimately fatal. Infections of metallic endovascular stents are potentially life-threatening complications and must be addressed urgently, including possible surgical intervention. (J Vasc Surg 2002;36:625-8.)

Effect of endovascular stent strut geometry on vascular injury, myointimal hyperplasia, and restenosis

Purpose: Early restenosis and the development of myointimal hyperplasia in stented blood vessels have been attributed to deep vascular injury with fracture of the internal elastic lamina (IEL). The purpose of this study was the evaluation of the vascular wall response to superficial injury (without IEL rupture) after balloon angioplasty and intravascular stent placement in porcine arteries and the determination of the effect of stent strut geometry on the degree of vessel injury and early restenosis. Methods: Balloon-expandable stainless-steel stents were placed into the iliac arteries of 10 Sinclair miniature swine that had been fed an atherogenic diet. A Palmaz stent, with rectangular struts and smooth corners, was randomly assigned to one iliac artery (group 1), and a novel stent, which was designed and manufactured in the laboratory with thicker struts and sharper corners specifically to induce large wall stress concentrations, was placed in the contralateral iliac artery (group 2). Intravascular ultrasound scan was used in all deployments to ensure accurate balloon sizing and to avoid stent overexpansion and deep vascular injury. At 90 days after implantation, the animals were killed, the stented vessels harvested, and histomorphometric analysis performed. Results: Deployment of novel stents in group 2 resulted in a statistically higher incidence rate of deep vascular injury (fracture of the IEL) compared with group 1, despite identical balloon size used for deployment (with Student t test, P < .05). Vessels with deep injury showed a 10-fold increase in myointimal thickening compared with those vessels in which the IEL remained intact. A statistically higher restenosis rate was observed for group 2 (33.5% ± 19.90%) compared with group 1 (20.39% ± 14.70%). For both stent designs, there was a trend toward lower degrees of restenosis within the mid-portion of the stent. For superficially injured arteries in both groups, no correlation was observed between the amount of vessel wall/medial layer compression and the development of restenosis from myointimal hyperplasia. Conclusion: Maintenance of an intact IEL is an important factor in the prevention of myointimal hyperplasia and restenosis in stented porcine iliac arteries. The alteration of stent strut height and geometry does not significantly affect restenosis and the development of myointimal hyperplasia in vessels with superficial injury. Superficial injury elicits a response that is independent of stent strut geometry and vessel wall compression. Stent strut profile may, however, increase local vessel wall stress concentrations, leading to IEL rupture and an exaggerated response to injury. (J Vasc Surg 2002;36:143-9.)

Balloon dilation and stent implant through the side of a previously placed intravascular stent: a new option for the interventionalist.

Intravascular stent placement for relief of vascular stenoses often requires that a stent be positioned across the origin of side-branch vessels. Most currently available peripheral vascular stents have a closed-cell design that will not allow catheter manipulation, dilation, or stenting through the stent cells. Therefore, if a side branch arising off a previously stented vessel is stenotic or if its origin has been compromised, transcatheter dilation of the branch vessel has not been possible. We report a series of successful balloon dilation and stent placement through the sides (cells) of previously placed IntraStent DoubleStrut LD stents in the aortic arch and abdominal aorta of pigs.

Angiography versus intravascular ultrasound-directed stent placement: a cost analysis from AVID

Angiography versus intravascular ultrasound-directed stent placement: a cost analysis from AVID

Clopidogrel

Clopidogrel is an ADP receptor antagonist that is indicated for the reduction of atherosclerotic events including myocardial infarction, ischaemic stroke and vascular death in patients with atherosclerosis manifested by recent stroke, myocardial infarction or established peripheral vascular disease. In the 19 185 patients enrolled in the multicentre, randomised double-blind CAPRIE study, the annual risk of the combined end-point of ischaemic stroke, myocardial infarction and death from vascular disease (vascular death) was significantly lower during treatment with clopidogrel 75 mg/day than aspirin 325 mg/day [5.3 vs 5.8%/year, respectively; relative risk reduction (RRR) 8.7%, p = 0.043] after a mean follow-up of 1.9 years. Clopidogrel provided even greater reductions in the risk of recurrent ischaemic events than aspirin in patients with a history of coronary artery bypass surgery, diabetes mellitus and in those receiving concomitant lipid-lowering therapy. Moreover there was a significant reduction in the incidence of hospitalisation in patients treated with clopidogrel. In a patient population (Saskatchewan, Canada) with a greater risk of ischaemic events than the CAPRIE study population, the number of patients needed to be treated with clopidogrel to prevent 1 ischaemic event was estimated to be 70 (vs 200 in the CAPRIE study). In randomised trials and registry surveys, clopidogrel 75 mg/day plus aspirin had similar efficacy (as measured by adverse cardiac outcomes) to ticlopidine 250mg twice daily plus aspirin during the 30 days after placement of intracoronary stents. Tolerability of clopidogrel was significantly better than ticlopidine in the randomised, double-blind CLASSICS study. Among patients treated with clopidogrel or aspirin in the CAPRIE study, the overall gastrointestinal tolerability of clopidogrel was generally better than that of aspirin; the frequency of gastrointestinal haemorrhage was significantly lower among patients treated with clopidogrel than aspirin. Diarrhoea, rash and pruritus were significantly more common with clopidogrel than aspirin. Clopidogrel was significantly more effective than aspirin in the prevention of vascular events (ischaemic stroke, myocardial infarction or vascular death) [corrected] in patients with atherothrombotic disease manifested by recent myocardial infarction, recent ischaemic stroke or symptomatic peripheral arterial occlusive disease [corrected] in the CAPRIE study. The overall tolerability profile of the drug was similar to that of aspirin, although gastrointestinal haemorrhage occurred significantly less often in clopidogrel recipients. The drug is widely used in combination with aspirin for the prevention of atherothrombosis after placement of intravascular stents, and available data suggest that this combination is as effective as ticlopidine plus aspirin for this indication.

Resultate von Ballonangioplastie und Stenting nach Clips- und Nahtarteriestenosen: Eine experimentelle Studie

Background: Comparative evaluation of balloon angioplasty following intravascular stenting after experimental stenoses caused by arterial reconstruction with vascular clips and conventional sutures. Materials and methods: A total of 24 arteriotomies were carried out at the carotid and common iliac arteries of pigs following a 10mm longitudinal arteriotomy and provocation of stenosis. Twelve of the arteries were reconstructed with vascular clips and 12 with conventional suture. Ultrasonography revealed stenosis fluctuating from 60–95% (PSV: 1.8–3.5 m/sec EDV: 1.3–1.47 m/sec PSV ratio &gt; 3.5). After 8 weeks, following digital subtraction angiography, which revealed &gt; 50% stenosis in all of the cases, balloon angioplasty followed by placement of intravascular stent was carried out. Results: All the angioplasties remained angiographically and macroscopically patent two months after without thrombus formation. Rupture during dilatation occurred in one of the sutured cases. Histologically no degenerative changes, necrosis or remarkable intimal thickness were observed in either method. Focal inflammatory reaction was seen in 2 sutured and in 1 clipped cases while intimal ulceration was observed in 2 sutured cases. All cases with clips presented an intact endothelial surface. Conclusion: Early experimental results suggested that arterial stenosis provoked by clipped reconstruction could be managed successfully by balloon angioplasty followed by placement of intravascular stent.

Stent for Acute Aortic Dissection

Intravascular stent placement is emerging as a less invasive treatment of acute aortic dissection originating in the descending thoracic aorta.

Intravascular stents do not cause microangiopathic hemolysis or thrombotic microangiopathy

An increased incidence of TTP has been noted among patients receiving intravascular stents to improve patency in diseased coronary, renal, and peripheral arteries. Placement of transjugular intrahepatic porto-systemic shunt stents is often associated with subsequent development of severe hemolysis. We have propsectively studied the development of microangiopathic hemolysis or TTP in patients undergoing intravascular stent placement for peripheral vascular or renal artery disease. Hemolysis was evaluated both before and after stent placement by measuring complete blood count, total bilirubin, lactate dehydrogenase (LDH), haptoglobin and reticulocyte count, and examining peripheral blood films of all patients. Coagulation parameters, blood urea nitrogen and creatinine were measured to exclude disseminated intravascular coagulation or thrombotic thrombocytopenic purpura as a potential cause of hemolysis. Seventeen patients (median age 69 years) were evaluated. One patient was on ticlopidine. Mean hematocrit fell from 41.8% pre-stenting to 35.5% post-stenting (P = 0.003) but without significant change in reticulocyte count (1.7 vs. 1.6%, P = 0.605), LDH (546 vs. 560 IU/l; P = 0.836), bilirubin (0.62 vs. 0.63 mg/dl; P = 1.0), or haptoglobin (183 vs. 158 mg/dl; P = 0.083). Thus, this drop in hematocrit could not be attributed to hemolysis. Peripheral blood films revealed fewer than 1% schistocytes before and after stent placement in all cases. Absence of significant changes in mean platelet count (240 vs. 210 × 109/L; P = 0.088), fibrinogen (385 vs. 378 mg/dl; P = 0.789), BUN (24.5 vs. 16.8; P = 0.079), and creatinine (1.38 vs. 1.24; P = 0.757) argue against development of TTP or DIC resulting from stent placement. No patient developed new renal impairment, a neurological syndrome, or unexplained fever after stent placement. At a mean of 6 weeks follow-up after stent placement, patients have not developed signs of hemolytic anemia or worsening renal function. Our findings argue against a primary risk of microangiopathic hemolytic anemia or TTP due to intravascular stents in patients not receiving ticlopidine. J. Clin. Apheresis 14:130–134, 1999. © 1999 Wiley-Liss, Inc.

Comparison of Conventional Angioplasty with the Palmaz Stent in the Treatment of Abdominal Aortic Stenoses from the STAR Registry

To retrospectively compare the safety and short-term efficacy of conventional percutaneous transluminal angioplasty (PTA) and PTA with the Palmaz balloon-expandable intravascular stent for the treatment of infrarenal abdominal aortic atherosclerotic stenoses. The records of 25 patients with infrarenal aortic stenoses treated by means of percutaneous techniques were retrieved from the SCVIR Transluminal Angioplasty and Revascularization (STAR) Registry and analyzed. Thirteen patients were treated with PTA alone and 12 were treated with the Palmaz intravascular stent. Technical success was achieved in 92% of patients treated with PTA alone and in 100% of those treated with the Palmaz stent. Significant improvements in lesion morphology, hemodynamics, clinical status, and ankle arm indexes were shown in both groups. There was no statistically significant difference in percent stenosis reduction, decrease in trans-stenotic gradient, or initial clinical outcome between the group treated by means of PTA and the group treated by means of PTA with the Palmaz stent. PTA and intravascular stent placement of atherosclerotic stenoses involving the infrarenal aorta are both safe and efficacious therapeutic modalities. At present, it does not appear that primary stent placement confers any short-term benefits over technically successful PTA in aortic stenoses.

Iatrogenic dissection of the abdominal aorta

Iatrogenic dissection of the abdominal aorta

An experimental study of endovascular stenting with special reference to the effects on the aortic vasa vasorum.

To evaluate the effects of bare stents and covered stents on the aortic wall, especially the vasa vasorum. Eight bare stents and nine covered stents were placed in the infrarenal aorta of nine dogs. The dogs were euthanized at 4-45 weeks after stent placement. The vasa vasorum was evaluated by microstereoscopy with vascular casting, and the histopathology of the aortic wall was examined by light microscopy. In the unstented normal aorta, vasa vasorum nourished the adventitia and the outer media, and the intima and inner media were avascular. In the stented segment, vascular dilatation and proliferation of vasa vasorum, medial atrophy, and intimal hyperplasia were observed, more prominent for covered stents than for bare stents. Intravascular stent placement caused not only medial atrophy and intimal hyperplasia but also proliferation of the vasa vasorum, probably due to hypoxia in the aortic wall.

Intraluminal signal intensity of iliac artery stents investigated by contrast-enhanced three-dimensional MR angiography

The purpose of this study is to investigate the intraluminal signal of iliac artery stents by contrast-enhanced three-dimensional magnetic resonance (MR) angiography with a short echo time. Ten patients with iliac arterial diseases treated by intravascular metallic stent placement were examined with a 1.5 T MR imager. Gadolinium-enhanced MR angiography depicted the intraluminal signal in Strecker stent, but not in the Wallstent and Palmaz stent. Strecker stent made of nonferromagnetic tantalum was the best-suited stent for use with contrast-enhanced MR angiography.

Intravascular stent and endovascular coil placement for a ruptured fusiform aneurysm of the basilar artery

The authors demonstrate the technical feasibility of using intravascular stents in conjunction with electrolytically detachable coils (Guglielmi detachable coils [GDCs]) for treatment of fusiform, broad-based, acutely ruptured intracranial aneurysms and review the literature on endovascular approaches to ruptured aneurysms and cerebral stent placement. A 77-year-old man presented with an acute subarachnoid hemorrhage of the posterior fossa. A fusiform aneurysm with a broad-based neck measuring 12 mm and involving the distal vertebral artery (VA) and proximal third of the basilar artery (BA) was demonstrated on cerebral angiography. The aneurysm was judged to be inoperable. Six days later a repeated hemorrhage occurred. A 15-mm-long intravascular stent was placed across the base of the aneurysm in the BA and expanded to 4 mm to act as a bridging scaffold to create a neck. A microcatheter was then guided through the interstices of the stent into the body and dome of the aneurysm, and GDCs were deposited for occlusion. The arteriogram obtained after stent placement demonstrated occlusion of the main dome and body of the aneurysm. The coils were stably positioned and held in place by the stent across the distal VA and BA fusiform aneurysm. Excellent blood flow to the distal BA and posterior cerebral artery was maintained through the stent. There were no new brainstem ischemic events attributable to the procedure. No rebleeding from the aneurysm had occurred by the 10.5-month follow-up evaluation, and the patient has experienced significant neurological improvement. Certain types of intracranial fusiform aneurysms may now be treated by combining intravascular stent and GDC placement for aneurysm occlusion via an endovascular approach. This is the first known clinical application of this novel approach in a ruptured cerebral aneurysm.