Balloon-mounted Stents Research Articles

Symptomatic stenosis of the vertebrobasilar arteries: results of extra‐ and intracranial stent‐PTA

About half of all transient ischaemic attacks (TIAs) or strokes in the posterior circulation are caused by the arterial stenosis. The purposes of this study were to determine the safety of stent-assisted percutaneous transluminal angioplasty (stent-PTA) and its efficacy for the prevention of recurrent stroke in patients with symptomatic artery stenosis in the extra- and intracranial posterior circulation. Forty-six patients with a previous stroke or TIA who received balloon-mounted coronary stents for vertebral artery origin stenosis (VAOS; 29 patients) or self-expanding nitinol stents for vertebrobasilar intracranial stenosis (VBIS; 17 patients) were followed-up for a mean of 24.1 (VAOS) and 12.7 (VBIS) months. When all cause morbidity/mortality within 30 days from stent-PTA and stroke or death from stroke in the treated vascular territory during the first 12 months of follow-up are combined, the incidence of periprocedural complications and disease progression for the first year is 10.3% in VAOS patients and 17.6% in the VBIS group. Vessel restenosis >/=50% was found in 52.0% of VAOS and in 32.1% of VBIS patients who completed 6 months follow-up. We observed a higher periprocedural complication rate for patients with VBIS and a higher rate of restenosis in VAOS patients after stent-PTA for symptomatic artery stenosis.

Stent Management of Coil Herniation in Embolization of Internal Carotid Aneurysms

Coil herniation into the parent artery after detachment is an uncommon complication of embolization of the intracranial aneurysm. We report our experience with stent reconstruction of the lumen and flow of the internal carotid artery (ICA) after coil herniation during embolization for intracranial ICA aneurysms and the possible mechanisms of coil herniation. A series of 216 consecutive patients was treated by endovascular coil embolizations for intracranial aneurysms. Of these patients, there were 9 (4 men, 5 women; 32-68 years of age) complicating with coil herniation into the ICA and undergoing stent deployment to reconstruct the ICA lumen (n = 8) or both lumen and flow (n = 1). Wide-neck aneurysms were found in 8 and narrow-neck, in 1. Aneurysms were in the posterior communicating artery (n = 5) and the paraophthalmic (n = 3) and cavernous portions (n = 1) of the ICA. Self-expandable stents were deployed in the ICA in 6; balloon-mounted stents were selected in 3. The causes of coil herniation appeared to be coil instability after detachment (n = 6), excessive embolization (n = 1), microcatheter-related problems (n = 1), or being pushed by subsequent coil embolization (n = 1). Endovascular stent placement to reconstruct the lumen and/or flow of the ICA was technically successful in all 9 patients; 1 needed a second stent due to further coil migration. No significant procedure-related complications were found. Clinical follow-up was 8-35 months. Coil herniation occasionally occurs during endovascular embolization of ICA aneurysms because of coil instability after detachment, excessive embolization, microcatheter-related problems, or pushing by subsequent coil embolization. In this small series, stent placement was safe and effective in the reconstruction of the arterial lumen and/or restoration of flow past a herniated coil mass.

STENT-MEDIATED WEDGING OF A CALCIFIC EMBOLUS TO RECANALIZE AN OCCLUDED MIDDLE CEREBRAL ARTERY

Calcific cerebral emboli are rare yet pose a difficult therapeutic challenge because of their lack of response to thrombolytic therapy and their propensity for fragmentation. A 75-year-old woman developed aphasia and hemiparesis after cardiac catheterization from a near-occlusive calcific embolus to the left middle cerebral artery origin. The calcific embolus was shown to be hemodynamically limiting by computed tomographic perfusion and diffusion-weighted magnetic resonance imaging. The patient was treated medically for 6 days with anticoagulation, antiplatelet, and hypertensive therapies but continued to deteriorate. A decision was made to attempt retrieval of the calcific embolus. Conventional intracranial mechanical clot and coil retrieval systems were used initially but were unsuccessful and caused migration of the calcific embolus, leading to complete occlusion of the left middle cerebral artery origin. At this point, the decision was made to wedge the calcific embolus against the vessel wall. A balloon-mounted coronary stent was used to achieve this successfully, resulting in recanalization of the middle cerebral artery trunk and flow restoration. Symptomatic calcific emboli, which are poorly responsive to pharmacological therapy and difficult to recover using conventional retrieval systems, may be treated by immobilization against the vessel wall using a balloon-mounted stent.

Carotid artery stenting in the Zucker rat: a novel, potentially ‘diabetes-specific’ model of in-stent restenosis

Both morbidity and mortality from coronary artery disease are higher in patients with diabetes. Moreover, percutaneous treatment of coronary artery disease using coronary stents – with either bare metal or the newer drug-eluting stents – is associated with poorer outcomes in patients with diabetes compared to those without, adding to their burden of disease. Surprisingly, given these broadly poor outcomes in patients with diabetes, there is a paucity of data using animal models examining the responses to stenting in a diabetic context. Such an animal model is proposed below. Five adult lean Zucker rats underwent stenting of the left common carotid artery. This was performed following an open cutdown under general anaesthesia (using 2% isofluorane) and an arteriotomy. Balloon-mounted human coronary stents (2.0 x 7mm, BiodivYsio, Abbott Vascular, Illinois, US) were placed in the common carotid artery under direct vision (OPMI Pico-microscope, Zeiss, Germany), advanced to a mid-arterial position and deployed at 12 atmospheres. The balloon was then removed, the arteriotomy ligated, and the animals allowed to recover. There was one peri-operative death, thought to be secondary to anaesthesia. After two weeks, the remaining four animals were sacrificed and the carotids dissected free en bloc. The tissue block was placed in 10% buffered formalin, then plasticised in methylmethacrylate. Sections (100 μm thick) were cut using a band cutting system (Exakt GmbH, Norderstedt, Germany), polished, stained with haematoxylin and eosin and imaged using light microscopy. A representative section is shown (figure 1). This processing technique leaves individual stent struts in situ. These were observed stretching and compressing, but not lacerating the media, suggesting a mild degree of vessel injury. The medial stretch and compression was associated with variable, but concentric, neointima (NI) formation (figure 1). This technique therefore demonstrates the potential to provide a specific model of in-stent restenosis in the setting of diabetes. Clearly, these are preliminary observations. The degree of NI formation has not yet been quantified in relation to the degree of vessel stretch; the molecular and cellular characterisation of the NI is yet to be elucidated; and the response to drug-eluting stent deployment has not yet been established. However, the technique is straightforward, low cost, readily available and importantly, to our knowledge, the first such description of carotid stenting in the Zucker rat, a readily available animal model of diabetes. In an environment where the clinical need for such models is clear, we trust that these preliminary observations will assist researchers in this important area of investigation. RESEARCH LETTER

Aneurysmabehandlung der Arteria carotis interna mit gecoverten Stents

Evaluation of the use of covered stents in treating pseudoaneurysms of the cervical and intracranial/extradural carotid artery and determination of the periprocedural and short- to mid-term complication rate. 8 patients with 9 spontaneous dissecting aneurysms of the cervical carotid artery--5 of which were symptomatic--plus one patient with ofthalmoplegia due to an aneurysm of the cavernous carotid artery were studied. While the latter was treated with a PTFE-covered balloon-mounted stainless steel stent (Jostent/Graftmaster), a self-expanding PTFE-covered Nitonol Stent (Symbiot) was used in all other cases. Intervention was performed with local anesthesia. Aspirin and Clopidogrel were both used as antiplatelet drugs. Clinical signs and symptoms and vascular imaging with DS, MR, CT angiography and ultrasound were recorded during patient follow-up, with a mean follow-up period of 14.6 months (4 - 30). We were able to treat 8 out of 10 aneurysms (80%) using covered stents. The aneurysms were immediately occluded and the associated stenoses of the parent vessel were eliminated. No clinically relevant complications occurred during the procedure or in the follow-up interval. In two cases, elongation of the carotid artery prevented the stent from being positioned over the aneurysm neck. These cases were shown to be stable with the use of antiplatelet drugs. Covered stents can be used in the treatment of pseudoaneurysms of the carotid artery as an alternative to long-term antithrombotic medication or surgery. In our study treatment was effective (80%) and free of complications in the short- and mid-term follow-up. Possible indications, technique and the use of imaging modalities for patient follow-up are discussed.

Emerging Endovascular Therapies for Symptomatic Intracranial Atherosclerotic Disease

Marc Fisher MD Section Editor Over the past 2 decades there has been an exponential growth in the scope of disease processes amenable to neuroendovascular treatment. The number and sophistication of the available devices and correspondingly the number of patients undergoing treatment has expanded accordingly. The development and implementation of these new procedures has in some cases outpaced our ability to carefully assess their merits. In comparison to peripheral and coronary vascular disease, neurovascular lesions are less common and far more heterogeneous, ranging from acquired cerebrovascular ischemic disease to hemorrhagic congenital arteriovenous malformations. Each individual disease process (eg, cerebral aneurysm) is composed of a myriad of lesions with different anatomical and pathophysiological characteristics. The natural history of these lesions and their subtypes are likewise poorly defined. For these reasons, personal bias, institutional custom, and anecdotal experience rather than scientific evidence have played a dominant role in guiding therapy. We must move toward collaborative multi-center efforts, prospective data collection and well designed randomized controlled trials to mature as a field over the coming decades. In some ways, symptomatic intracranial atherosclerotic disease (SxICAD) represents an optimal disease process with which to establish this progress toward evidenced based treatment. SxICAD is considerably less heterogeneous than other cerebrovascular disease processes and is arguably best suited as a paradigm for study. In the current article we have attempted to review the available evidence describing the natural history of medically treated SxICAD to determine those patients best suited for invasive treatment strategies. We will also discuss the available treatment modalities which may represent viable options to medical therapy. These data form the basis for the design of future prospective multicenter studies to evaluate the relative merits of interventional treatment. Any invasive treatment strategy for symptomatic intracranial atherosclerosis must satisfy two criteria to establish viability as a …

Stent Placement For Intracranial Cysts By Combined Stereotactic/Endoscopic Surgery

The treatment of space-occupying cystic lesions includes percutaneous cyst aspiration, marsupialization, percutaneous ventriculocystotomy, or Rickham catheter implantation. In some patients, the cysts tend to recur and repeated evacuations are necessary. The authors present a new treatment method with internal drainage of cysts into the ventricular system using a balloon-mounted vascular stent. Six patients with cysts of low-grade gliomas, one with monocystic craniopharyngioma, and one with suprasellar arachnoid cyst were treated between September 2003 and May 2005. All patients were symptomatic after multiple previous treatments. Stent implantations were performed under local anesthesia in adults and under general anesthesia in children. In all patients, the stereotactic frame and computed tomographic and magnetic resonance fusion were used for an optimized approach. The treatment was performed in a compassionate manner and the patients were informed about the off-label use of the device. Stent placement was successful in all eight patients without procedure-related complications. Improvement of clinical symptoms was seen in seven out of eight patients. Seven out of eight cysts decreased in size within a follow-up period of up to 23 months (mean, 17 mo; median, 18 mo; range, 6-23 mo). The first patient showed recurrence of the tumor cyst 3 months after initial treatment with a Herkulink stent (5 x 18 mm), followed by retreatment with an Omnilink stent (6 x 28 mm; Guidant Corp., Santa Clara, CA). Stenting was ineffective in one patient. Treatment of intracranial cystic lesions by internal drainage is possible with the use of stent-assisted ventriculocystostomy.

New Technique for Fenestration of the Interatrial Septum

Achieving controlled flow between the systemic and pulmonary venous circulations is desirable in many complex congenital heart diseases. This includes the Fontan circulation, primary pulmonary hypertension, double inlet ventricles, or hypoplastic left heart with obstruction to the atrioventricular valve. As no specific device is available for this purpose, we developed a balloon-mounted stent technique to achieve a predetermined-sized fenestration of an atrial baffle in a patient with Fontan circulation. The details of the technique are described.

Angioplasty and stenting of intracranial stenosis

The review summarizes recent advances in angioplasty and stenting of intracranial atherosclerotic stenosis. Several single-center studies show that, with the technological advancements in device technology, intracranial stenting is feasible even in the distal internal carotid artery or middle cerebral artery. However, the clinical outcomes vary between moderate and high risk rates for morbidity and mortality. To date, the only prospective multi-center study that has been conducted is the SSYLVIA (Stenting of Symptomatic Atherosclerotic Lesions in the Vertebral or Intracranial Arteries) study, which demonstrated stroke rates of 6.6% and 13.1% at 30 days and 1 year, respectively. A unique feature of this trial is the assessment of restenosis rates and their potential association with clinical symptoms and risks. A promising new concept for stent-assisted procedures in the intracranial vasculature is the use of self-expanding stents. The high flexibility of these stents makes them suitable for treatment of lesions of the distal internal carotid artery and middle cerebral artery that are either inaccessible or difficult to reach with a balloon-mounted stent. Additionally, these self-expanding stents may result in fewer traumas to the parent vessel and in reduced rates of iatrogenic complications and restenosis. Intracranial angioplasty with or without stenting is a promising treatment option. Patient selection, careful periprocedural medical management, and a highly skilled neuroendovascular surgeon are all required to perform the procedure with an acceptable risk. If stenting is to be shown to be a safe therapeutic alternative, prospective trials comparing stenting with optimal medical treatment need to be performed.

Cardiological aspects in preoperative anaesthesiological evaluation: old heroes, new shadows

Cardiological aspects in preoperative anaesthesiological evaluation: old heroes, new shadows

A Comparison of Balloon-Mounted and Self-Expanding Stents in the Carotid Arteries:Immediate and Long-term Results of More Than 500 Patients

<b>A Comparison of Balloon-Mounted and Self-Expanding Stents in the Carotid Arteries:</b>Immediate and Long-term Results of More Than 500 Patients

In vitro evaluation of c7E3-Fab (ReoPro) eluting polymer-coated coronary stents.

Stent thrombosis and in-stent restenosis remain problematic in certain patient sub-groups. c7E3-Fab (ReoPro, abciximab) inhibits the platelet glycoprotein IIb/IIIa receptor as well as the smooth muscle cell alpha(v)beta3 receptor, and thus may influence both processes, especially if high local concentrations could be achieved. We have studied the adsorption and elution characteristics of c7E3-Fab on commercially available polymer-coated stents. We have also investigated the effect of such antibody binding on platelet deposition in vitro, and on antibody deposition into ex vivo human saphenous vein wall to assess whether such stents may influence stent thrombosis and restenosis. Adsorption was measured using a radioisotope technique after immersing segments of polymer-coated stents in c7E3-Fab solutions. Uptake was dependent on antibody concentration and duration of immersion of wire in the solution. After 22 h (at 5 mg ml(-1)), 1146+/-101 ng cm(-1) wire was adsorbed. In an in vitro perfusion circuit, the antibody eluted slowly, with 53% remaining after 12 days washing. To determine the value that such stents might have in clinical practise, adsorption to balloon-mounted stents was assessed at room temperature, using commercially available c7E3-Fab (2 mg ml(-1)). Efficacy of eluting c7E3-Fab was determined by measuring deposition of 111-Indium platelets. Immersing stents in c7E3-Fab for 20 min inhibited platelet deposition by 82.3% compared to controls (P=0.018). Deployment of treated stents in ex vivo saphenous vein resulted in the deposition of c7E3-Fab in the intima and media. c7E3-Fab can be passively adsorbed onto polymer-coated stents. It elutes slowly and in a predictable manner, significantly inhibiting platelet deposition in vitro. These studies pave the way to developing stent-based delivery of a potent anti-platelet agent that may additionally affect smooth muscle cell activity.

Coronary stents: Impact on modern interventional practice

SummaryThere has been a rapid increase in coronary-stent placement as part of routine coronary angioplasty in the last few years. There are many reasons for this, including rapid developments in stent and balloon technology, which have resulted in low-profile, securely balloon-mounted stents, facilitating placement in complex coronary lesions. The indications for stent placement have been widened so that not placing a stent takes place in only a significant minority of procedures. In many centres stent placement accompanies > 70% of coronary angioplasty procedures. New developments in stent technology, including covered stents, coated stents and stents for particular uses, such as bifurcation lesions, continue to expand the indications for this type of angioplasty technology. The increased use of stents has been facilitated by the introduction of effective new antiplatelet drugs, which have reduced the need for systemic anticoagulation of stented patients. There are strong indications that stent placement affects the natural history of restenosis following angioplasty, significantly reducing the incidence of this condition.

Retrieval of a migrated coronary stent by means of an alligator forceps catheter

Stent migration and embolization are well-known complications of intracoronary stenting with balloon-mounted stents. During an elective stenting procedure of a proximal right coronary artery stenosis, a 3.5 mm Wiktor stent (Medtronic Inc., Minneapolis) was displaced from its delivery balloon. The guiding catheter and the delivery system were withdrawn, leaving the stent around a 3 m 0.014 inch High Torque floppy guidewire (ACS, Santa Clara, CA) in the abdominal aorta. An 40 cm 5F Alligator Forceps catheter (Cook OB/Gyn., Spencer, IN), introduced through a cut-off 8F coronary guiding catheter, allowed improved torque control of the retrieval catheter and a safe and successful withdrawal of the stent through the arterial introducer sheet.

Enalapril in the prevention of restenosis following intracoronary intervention in a swine model.

Restenosis following percutaneous transluminal coronary angioplasty continues to be a major limitation of the procedure. To test whether an angiotensin-converting enzyme inhibitor may reduce restenosis, this study utilized an atherosclerotic, stented, Hanford miniature swine model of restenosis. Each animal first was started on an atherogenic diet and had balloon abrasion of the left anterior descending and right coronary arteries. Four months later, balloon-mounted coil stents were placed into the abraded coronary arteries of each animal. Twenty-four animals then were randomly assigned to one of two groups: enalapril, and control. The enalapril group received 50 mg orally twice daily starting 1 week before intracoronary stenting. Follow-up 2 months later revealed angiographic stenosis in the control group of 30% +/- 13%/25% +/- 10% (left anterior descending/right coronary artery) versus 37% +/- 9%/20% +/- 11% in the enalapril group (P = not significant). The change in minimal lumen diameter from immediately after stenting to follow-up was not significantly different between control and enalapril groups. Area stenosis and maximal intimal thickness obtained by morphometric analysis were also compared, and the mean percentage area stenosis for the control group was 39 +/- 12%/31% +/- 16% and for enalapril 36% +/- 14%/35% +/- 19%. The maximal intimal thickness in the control group was 573 microns +/- 204 microns/605 microns +/- 266 microns and in the enalapril group 530 microns +/- 220 microns/424 microns +/- 237 microns. There was no statistical difference. Enalapril fails to reduce restenosis in this animal model.