Stenting within a stent for treatment of residual dissection

We describe the management of residual dissection protruding through the struts of a Wiktor stent (Medtronic Inc., Minneapolis, MN) implanted in bailout conditions. In general, negotiating a stent through an expanded Wiktor stent is not recommended, but using this strategy, an AVE (Advanced Vascular Engineering, Santa Clara, CA) Micro stent was successfully implanted inside the Wiktor stent, leading to an excellent final angiographic result. Cathet. Cardiovasc. Diagn. 40:319–321, 1997. © 1997 Wiley-Liss Inc.     

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 The guiding catheter and the delivery system were withdrawn, leaving the stent around a 3 m 0.014 inch High Torque floppy guidewire (ACS, Santa Clara, CA) in the abdominal aorta.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. © 1993 Wiiey-Liss, Inc.     

Initial clinical results with the Wiktor stent: a new balloon-expandable coronary stent

The Wiktor stent, a new coronary balloon-expandable tantalum stent, was implanted in 17 patients for other wise nonmanageable occlusion after balloon angioplasty (n = 11) and for recurrent restenosis (n = 6). Stents of 3.0 to 4.0 mm were implanted (right coronary artery: n = 10, left anterior descending artery: n = 4, left circumflex artery: n = 2, venous graft: n = 1). All patients were fully anticoagulated initially with heparin followed by coumadin for 3 months and were treated with acetylsalicylic acid indefinitely. Due to its good radiopacity, the device could be placed easily without complications. Early occlusion occurred in one patient after 8 h probably due to friable atheromatous material prolapsing between the meshes of the stent. Late occlusion occurred in another patient who was admitted in cardiogenic shock after pre-hospital reanimation and was stented after occlusive disection following balloon angioplasty of an occluded right coronary artery. In this patient with severe hypoxic brain damage, reocclusion and reinfarction to which the patient finally succumbed occurred following cessation of anticoagulation. Histology demonstrated occlusive thrombosis without evidence of a neointimal covering of the stent. Another thrombotic occlusion due to inadvertent omission of anticoagulation occurred in another patient two weeks after stenting. Control angiography after 6 months in 12 patients revealed restenosis in two patients (50% and 80%). The patient with 80% restenosis of the right coronary artery and pathologic results during stress testing underwent surgical revascularization. The other patient with a 50% restenosis of the right coronary artery was managed medically as he was asymptomatic and without evidence of ischemia during stress testing.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immediate changes in stenosis geometry following stent implantation: comparison between a self-expanding and a balloon-expandable stent

The immediate changes in stenosis geometry following Wallstent and Wiktor stent implantation in native coronary arteries were compared in 92 patients (46 in each group) using automated edge detection. Patients with comparable baseline stenosis characteristics were selected. Lesions were matched for lesion site, reference diameter, and minimal luminal diameter. In both groups, the stented coronary artery was the left anterior descending artery in 27 patients (59%), the left circumflex artery in four patients (9%), and the right coronary artery in 15 patients (33%). The baseline reference diameter was 2.86 +/- 0.39 mm and 2.87 +/- 0.42 mm in the Wallstent and Wiktor stent study group, respectively (NS). The baseline minimal luminal diameter was identical in both groups (1.13 +/- 0.24 mm). The nominal size (mean +/- SD) of the unconstrained Wallstent was 3.5 +/- 0.3 mm and 3.3 +/- 0.3 mm for the Wiktor stent (P less than 0.05). Both types of stents resulted in a similar increase in minimal luminal diameter immediately following implantation (Wallstent: 2.34 +/- 0.38 mm, Wiktor stent: 2.43 +/- 0.27 mm, NS). Furthermore, there was a similar decrease in diameter stenosis and increase in minimal luminal cross-section area following implantation of both stents. These morphological changes were associated with a normalization of the hemodynamic parameters in both groups. It is concluded that, although the Wallstent and Wiktor stent are different in design and mechanical characteristics, there is a similar immediate improvement in stenosis geometry following implantation of both devices.     

Randomized study to compare balloon angioplasty and elective stent implantation in venous bypass grafts: the Venestent study.

The aim of the study was to compare acute and long-term angiographic and clinical outcome of balloon angioplasty and elective stenting in de novo lesions in the body of a saphenous vein graft (SVG). A total of 150 patients, with de novo lesions in SVG, were randomly assigned to balloon angioplasty or elective Wiktor I stent implantation. The angiographic restenosis rate at 6-month follow-up was 32.8% in the balloon group and 19.1% in the stent group (P = 0.069). At 1-year follow-up, target vessel revascularization rate was 31.4% vs. 14.5% (P < 0.05), and event-free survival was 60.0% vs. 76.3% (P < 0.05) for the balloon and stent group, respectively. Elective stent implantation in de novo SVG lesions is associated with a significant lower target vessel revascularization rate and a significant higher event-free survival at 1-year follow-up as compared to balloon angioplasty.     

Retrieval of undeployed stents from the right coronary artery: report of two cases

Two patients are described in whom an undeployed stent (1 Wiktor and 1 Palmaz-Schatz) was retained in the proximal segment of the right coronary artery during coronary angioplasty. In both cases the stent was caught by a technique using a second guidewire. The stent was removed in the first patient during bypass surgery; in the second patient it was removed from the femoral sheath© 1993 Wlley-Liss, Inc     

Should we avoid ostial implantations of wiktor stents?

Complications arising during stent implantations in coronary arteries have been reduced by technological progress and the accumulated experience of interventional cardiologists. Retrospective and prospective randomized studies with several types of stents are currently available and show improved short and mid-term results. Wiktor stent provides increased flexibility for ease of implantation particularly in curved lesions. However, the flexibility of the Wiktor stent is also associated with low resistance in the longitudinal axis. We report four cases (in 4 out of 6 ostial lesions treated and 4 out of 43 Wiktor stents implanted during a 9-month period) in which stents have become unraveled during procedures on ostial lesions (2 saphenous venous grafts and 2 native coronary arteries). Death occurred in one case and one patient was treated by emergency coronary bypass surgery. In three cases the distal extremity of the guiding catheter streched the stent meshes during the final control angiograms, and in one case the stent was stretched during withdrawal of the deflated balloon into the guiding catheter. We believe that it is preferable to avoid using this stent in ostial lesions. © 1994 Wiley-Liss,Inc..     

Placement of multiple and different stent types for very long dissections during coronary angioplasty

We have been investigating the safety and efficacy of multiple and different stent types placed in the unfavorable situation of a very long dissection (>20 mm) after coronary angioplasty. We report our preliminary experience in 20 patients who were treated by the following combinations: Palmaz-Schatz and Micro stent (14 patients); Walistent and Micro stent (4 patients); Wiktor and Micro stent (1 patient); and Palmaz-Schatz, Micro, and Walistent (1 patient). Normal distal flow was restored in all except one (no reflow phenomenon) patient and complete covering of the dissection was obtained in all but two patients. Event-free survival at 30 days was 90% (18 of 20 patients). During follow-up (mean period: 8 ± 3 months), two patients died. Of the 18 other patients, 16 remained asymptomatic and free of complications. Symptomatic restenosis was treated by standard angioplasty in the two remaining patients. In conclusion, placement of different stent types seems a feasible, safe, and efficient treatment for very long dissections caused by standard angioplasty. © 1996 Wiley-Liss, Inc.     

Effect of stent design on reduction of elastic recoil: A comparison via quantitative intravascular ultrasound

The increase in minimum lumen diameter achieved by coronary stent placement can be further enhanced by reducing the immediate recoil that occurs after stent deployment. The effect of various stent designs—flexible coils, slotted tubes, and a locking stent—on minimization of postdilation stent recoil was evaluated using an in vitro model of circumferential compression. The stents were expanded to 7 atm (3.82 ± 0.02 mm); as pressure was reduced, lumen diameter and cross-sectional area (CSA) were determined by on-line intravascular ultrasound imaging (30 MHz) positioned inside the dilating balloon (n = 10–15 inflation-deflation cycles). Stent recoil was assessed by calculation of percent change in CSA from 7 atm to negative balloon pressure: −33.1 ± 5.6%(GR-II) and −22.4 ± 3.8%(Wiktor) in the coil stents; −20.0 ± 4.2%(JJIS coronary), −8.4 ± 2.6%(JJIS biliary), and −6.9 ± 1.5%(Multilink) in the slotted tube stents; and −1.9 ± 3.2%in the Navius ZR1 locking stent (P<0.05 vs. Multilink, P<0.0001 vs. others). A range of resistances to recoil is demonstrated by this model, with coil stent designs undergoing greater elastic recoil than slotted tube stent designs. The locking stent design demonstrated the greatest radial strength and the most reduction in elastic recoil. Cathet. Cardiovasc. Intervent. 47:251–257, 1999. Published 1999 Wiley-Liss, Inc.     

Morphologic change in coronary artery stenosis with the medtronic Wiktor™ stent: Initial results from the core laboratory for quantitative angiography

The purpose of this study was to assess the early changes in stenosis geometry after implantation of the Medtronic Wiktor? stent in human coronary arteries. Morphologic changes were evaluated by quantitative coronary angiography using automated edge detection. The hemodynamlc significance of the morphologic changes were assessed by the calculation of the theoretical pressure drop across the dilated and stented stenosis derived from the Poiseuile and turbulent resistances assuming a coronary blood flow of either 0.5, 1, or 3 ml/sec. Fifty patients were studied before and immediately after stent implantation. The stented coronary artery was the left anterior descending artery in 26 patients, the circumflex artery in eight patients, and the right coronary artery in 16 patients. Stent implantation resulted in an additional increase in the minimal lumlnal cross-sectional area and minimal luminal diameter of the dilated vessel without changing the curvature of the stenosis. Furthermore, there was a significant reduction of the “plaque area.” This was associated with a normalization of the calculated resistances to flow and presure drop across the stenosis. To a minimal extent, recoil (0.1 ± 0.36 mm) was observed after stent implantation.     

Additional luminal area gain by intravascular ultrasound guidance after coronary stent implantation with high inflation pressure

Aims: Studies by intravascular ultrasound demonstrated inadequate expansion in a large number of stents, which lead to the increase of inflation pressures for stenting. The present study examined whether routine use of high-pressure inflation would be sufficient for an optimum stent expansion without sonographic guidance. Methods and results: Two types of single coronary stents (Palmaz-Schatz in 54, and Wiktor in 25) were implanted with inflation pressures of 16–20 atm in 79 nonocclusive coronary lesions. IVUS before stenting was used in 78% to select the adequate stent size. Intravascular ultrasound after stenting was used to assess the minimum stent area and diameter, the reference areas, and the strut apposition to the vessel wall. The difference between the area of the expanding balloon and the stent area was calculated as the luminal deficit of the stent. Completeness of stent expansion required full strut apposition and lesion coverage, and a minimum stent area that was larger than the distal reference, and larger than 60% of the proximal reference. Intravascular ultrasound before stenting lead to an increase of the stent size in 47%. After high-pressure expansion, even with the optimized balloon size, 8% of stents had struts protruding into the lumen. The stent area (6.87 ± 1.93 mm²) was significantly smaller than both the proximal (9.59 ± 2.91 mm²; p<0.001) and distal reference area (8.23 ± 3.03 mm²; p<0.001). The criteria for complete expansion were met in 48%. The expansion with a larger high-pressure balloon in 28 stents lead to an increase of the stent area by 19% (8.19 ± 2.24; p<0.001), and full stent apposition in all cases. The criteria of stent expansion were met in 82%. A wide range of the luminal deficit upto 48% was observed, which was not related to sonographic lesion characteristics, except in lesions with complete circumferential calcifications. The different stent designs were characterized by a slightly lower luminal deficit in slotted-tube stents (23 ± 13% vs. 28 ± 12%; p=0.11) and a better index of stent symmetry as compared with the coil stent (0.87 ± 0.08 vs. 0.82 ± 0.09; p<0.05). Conclusion: Routine use of high-pressure stent expansion did not lead to a sufficient stent expansion, even when the initial stent size had been guided by intravascular ultrasound. Further stent dilatation with larger balloons under ultrasound guidance would be required to optimize the luminal area gain.     

Novel use of a stent graft for uncontrollable intraprocedural stent thrombosis in a patient with acute myocardial infarction

We report the case of a patient who developed uncontrollable intraprocedural stent thrombosis (IPST) during an emergent percutaneous coronary intervention for acute myocardial infarction that was mitigated only by covering the culprit lesion with a stent graft. Although several factors can induce stent thrombosis, IPST was likely a result of intrastent plaque protrusion in this patient. This is the first case report on the use of stent graft implantation as an effective bailout procedure for uncontrolled IPST. The findings described in this case study warrant the adoption of stent grafts for the complete sealing of plaque protrusion in lesions.     

肝素涂层支架植入术对冠心病患者血浆内皮素、丙二醛水平的影响及临床意义

目的 :研究肝素涂层支架植入术对冠状及体循环中血浆内皮素 （ET）和丙二醛 （MDA）水平的影响。方法　选择冠心病患者 30例 ,随机植入普通无涂层支架 （NCS） 16例和肝素涂层支架 （HCS） 14例 ,于手术前后不同时间点 ,同时采集冠状静脉窦和外周肘静脉血检测血浆 ET- 1和 MDA浓度。结果　 1NCS组 :ET- 1水平在支架后即刻和支架后 12 h呈现大小两个高峰 ,MDA水平在支架后 5 m in达高峰 （P<0 .0 1） ;2 HCS组 :ET- 1水平在支架后5 m in,10 min和 12 h明显低于同时间点 NCS组水平 （P值分别 <0 .0 5 ,<0 .0 1和 <0 .0 5 ） ,MDA水平于支架后5 m in至术后 1d均明显低于 NCS组 （均 P<0 .0 5 ）。结论　 HCS可降低术后 ET- 1和 MDA水平 ,这可能对支架植入术后防止急性血管痉挛和 （亚 ）急性血栓形成的发生有一定保护作用     

Increasing arterial wall injury after long-term implantation of two types of stent in a porcine coronary model

Aims There is increased late loss in luminal diameter following long-termcoronary stenting, compared with balloon angioplasty. We evaluatedshort- and long-term vessel wall injury after experimental implantationof two stent designs as well as balloon angioplasty and theirrelationship to neointimal hyperplasia. Methods and Results Wiktor stents and Palmaz-Schatz stents were implanted in normalcoronary arteries of pigs (balloon/artery ratio: 0·9–1·1).In control coronary arteries, balloon angioplasty was performed.At 1, 4 and 12 weeks, the vessel injury score, neointimal thicknessand inflammatory response were assessed by histology.The vesselinjury score increased over time in both Wiktor and Palmaz-Schatzstents: 0·9±0·1, 1·5±0·5and 1·7±0·6 (mean±SD) for Wiktorstents and 0·7±0·2, 1·0±0·1and 1·2±0·3 for Palmaz-Schatz stents at1, 4 and 12 weeks follow-up, respectively. No increase in injurywas seen in balloon angioplasty controls. Inflammation was seenin both stented groups but was absent 12 weeks after balloonangioplasty. No strong correlation between injury and neointimalthickness was apparent. Conclusion Stents induce chronic injury in contrast to balloon angioplasty.Stent design (coil vs slotted tube) as well as inflammationmay influence vessel response.     

Development of a reexpandable covered stent for children.

The use of covered stents in children is limited by the need for a large long sheath for delivery and the impossibility of redilation once implanted. The authors developed a reexpandable covered stent implantable in children through a small sheath and evaluated its clinical feasibility in mini piglets. An original Palmaz stent was covered with a polyurethane membrane that could be stretched up to 700%. Under general anesthesia, the authors implanted the covered stents in six mini piglets using a long sheath with a diameter approximately 1 French larger than the recommended size required to deliver an uncovered Palmaz stent. The implantation technique was similar to conventional stent implantation. In six piglets, the stent could be redilated from 7.5 to 8.7 mm 28-70 days after implantation. Macroscopic and microscopic examination showed intimal coverage of the coating with minimal inflammatory reaction around the stent. Our newly designed reexpandable stent covered with a polyurethane membrane is promising for use in children.     

Antiplatelet treatment with cilostazol after stent implantation

Objectives—To evaluate the efficacy of cilostazol, a new synthetic inhibitor of phosphodiesterase, in preventing stent thrombosis after successful implantation.
Design—Preliminary prospective study.
Setting—A single coronary care unit in Japan.
Patients—Elective, bailout, or primary stents were implanted in 85 consecutive patients with 93 lesions. Primary stent implantation was performed in 18 patients with acute myocardial infarction. Patients received 200 mg cilostazol and 243 mg aspirin after stenting.
Main outcome measures—Stent thrombosis, major and minor complications, and side effects were assessed in the six months after stenting.
Results—Gianturco-Roubin stents were implanted in 37 lesions, Wiktor stents in 55, and Palmaz-Schatz stents in 27. Multiple stents were used in 26 lesions. There was no mortality, stent thrombosis related Q wave myocardial infarction, emergency bypass surgery, repeat intervention, or vascular complications in the six months of follow up. Acute or subacute closure did not occur after stenting. There were no serious side effects such as leucopenia and/or abnormal liver function for three months. Cilostazol was withdrawn in one patient because of skin rash. Patients who underwent primary stenting had no clinical events, such as acute or subacute thrombosis, or side effects.
Conclusions—Cilostazol is an effective antiplatelet agent with minimum side effects after elective, bailout, or primary stent implantation.

Keywords: antiplatelet treatment; stents; stent thrombosis; cilostazol     

Late aortic dislocation of a stent following stent angioplasty for ostial renal artery stenosis.

A patient with left RAS was treated by stent angioplasty followed by a multivessel percutaneous coronary intervention. Six months later, an aortic dislocation of the stent was diagnosed. The fully expanded stent was caught with a balloon catheter and fixed in the left external iliac artery. Stent migration after initially successful stent angioplasty for RAS is possible. Fully expanded, dislocated balloon-expandable stents can be secured by implanting them into the iliac artery.     

Wiktor stent implantation in patients with restenosis following balloon angioplasty of a native coronary artery.

Intracoronary stenting has been introduced as an adjunct to balloon angioplasty aimed at overcoming its limitations, namely acute vessel closure and late restenosis. This study reports the first experience with the Wiktor stent implanted in the first 50 consecutive patients. All patients had restenosis of a native coronary artery lesion after prior balloon angioplasty. The target coronary artery was the left anterior descending artery in 26 patients, the circumflex artery in 7 patients and the right coronary artery in 17 patients. The implantation success rate was 98% (49 of 50 patients). There were no procedural deaths. Acute or subacute thrombotic stent occlusion occurred in 5 patients (10%). All 5 patients sustained a nonfatal acute myocardial infarction. Four of these patients underwent recanalization by means of balloon angioplasty; the remaining patient was referred for bypass surgery. A major bleeding complication occurred in 11 patients (22%): groin bleeding necessitating blood transfusion in 6, gastrointestinal bleeding in 3 and hematuria in 2. Repeat angiography was performed at a mean of 5.6 +/- 1.1 months in all but 1 patient undergoing implantation. Restenosis, defined by a reduction of greater than or equal to 0.72 mm in the minimal luminal diameter or a change in diameter stenosis from less than to greater than or equal to 50%, occurred in 20 (45%) and 13 (29%) patients, respectively. In this first experience, the easiness and high technical success rate of Wiktor stent implantation are overshadowed by a high incidence of subacute stent occlusion and bleeding complications.(ABSTRACT TRUNCATED AT 250 WORDS)     

硅酮支架与覆膜金属支架并发症的对比观察

目的对照观察硅酮支架与Z型不锈钢覆膜金属支架置入后的并发症,为临床支架的选择提供参考。方法 2014年4月至2015年2月因气道狭窄或气道瘘65例患者置入硅酮支架,77例患者置入覆膜金属支架,术后定期支气管镜检查,观察2个月内两组病例的主要并发症。结果硅酮支架组置入分叉型支架45例、沙漏状支架7例、直筒型支架13例;覆膜支架组置入分叉型支架70例、直筒型支架7例。两组并发症比较:痰液潴留硅酮支架50例(76.9%)、覆膜支架61例(79.2%),相差不显著(P0.05);肉芽增生硅酮支架39例(60.0%)、覆膜支架69例(89.6%),相差显著(P0.01);支架移位:分叉型及沙漏状支架均无移位,直筒型支架移位硅酮支架2例(15.3%)、覆膜支架6例(85.7%),相差显著(P0.01);顽固性咳嗽硅酮支架4例(6.1%)、覆膜支架7例(9.0%),相差不显著(P0.05)。因肉芽增生明显经处理效果差,9例覆膜支架取出支架,硅酮支架未因肉芽增生取出支架。结论硅酮支架与覆膜支架比较,硅酮致肉芽增生较轻,其直筒型移位较少,建议对需长期放置支架的患者,优先考虑硅酮支架。     

Clinical applications of a new enhanced stent imaging technology

Enhanced Stent Imaging (ESI) refers to a rapidly evolving class of imaging tools that seek to provide enhanced visualization of coronary stent architecture with minimal disruption to the catheterization laboratory workflow. Various ESI stent platforms are available, all of which utilize a brief cine acquisition of a deflated balloon within a stent to generate a motion‐corrected, enhanced image of the stent. The enhanced image permits detailed assessment of stent architecture, integrity, and positioning relative to other stents. We present two illustrative cases of percutaneous coronary intervention utilizing a new ESI platform. The relevant literature is briefly reviewed.© 2013 Wiley Periodicals, Inc.