Incomplete Stent Expansion Research Articles

Side branch ostium stenting with main vessel drug-eluting balloon kissing (BOMB): An innovative approach for isolated coronary stenosis at side branch ostium

Side branch ostium stenting with main vessel drug-eluting balloon kissing (BOMB): An innovative approach for isolated coronary stenosis at side branch ostium

Superficial coronary calcium analysis by OCT: Looking forward an imaging algorithm for an automatic 3D quantification

Coronary artery calcium (CAC) is a sign of significant coronary artery disease [1]. Superficial calcium [2] may be associated to several procedural and long term complications of percutaneous coronary intervention (PCI) [3]. The reduced wall compliance in a calcific lesion may lead to inadequate (incomplete and asymmetrical) stent expansion, which is associated to thrombosis [4] and restenosis [5]. Since calcifications are very often eccentric, an inhomogeneous stiffness distribution within the vessel wall occurs; this structural setting is the harbinger of dissection and of the vessel perforation when high pressure balloon dilations are performed to prepare the lesion for stent implantation, due to a non uniform distribution of the shear stress generated by the balloon catheter inflation.

Intravascular ultrasound assessed incomplete stent apposition and stent fracture in stent thrombosis after bare metal versus drug-eluting stent treatment the Nordic Intravascular Ultrasound Study (NIVUS)

This prospective multicenter registry used intravascular ultrasound (IVUS) in patients with definite stent thrombosis (ST) to compare rates of incomplete stent apposition (ISA), stent fracture and stent expansion in patients treated with drug-eluting (DES) versus bare metal (BMS) stents. ST is a rare, but potential life threatening event after coronary stent implantation. The etiology seems to be multifactorial. 124 patients with definite ST were assessed by IVUS during the acute ST event. The study was conducted in 15 high-volume percutaneous coronary intervention -centers in the Nordic-Baltic countries. In early or late ST there were no differences in ISA between DES and BMS. In very late ST, ISA was a more frequent finding in DES than in BMS (52% vs.16%; p=0.005) and the maximum ISA area was larger in DES compared to BMS (1.1 ± 2.3mm(2) vs. 0.1 ± 0.5mm(2); p=0.004). Further, ISA was more prevalent in sirolimus-eluting than in paclitaxel-eluting stents (58% vs. 37%; p=0.02). Stent fractures were found both in DES (16%) and BMS (24%); p=0.28, and not related to time of stent thrombosis occurrence. For stents with nominal diameters ≥ 2.75 mm, 38% of the DES and 22% of the BMS had a minimum stent area of less than 5mm(2); p=0.14. Very late stent thrombosis was more prevalent and associated with more extensive ISA in DES than in BMS treated patients. Stent fracture was a common finding in ST after DES and BMS implantation.

Sealing old plaques, seeding new plaques

In stent restenosis (ISR) is a heterogeneous phenomenon. The classical paradigm is neointimal proliferation in response to vessel wall injury often in combination with incomplete stent expansion. Drug-eluting stents (DES) have been designed to reduce or eliminate hyperplasia and in fact dramatically reduced restenosis and target lesion revascularization (TLR). The drawback of DES has been an increase in late and very late stent thrombosis, a potentially life-threatening complication considered a consequence of delayed and incomplete strut endothelialization. The article of Habara et al .1 challenges this concept by analysing in-stent restenosis with optical coherence tomography (OCT) in the first generation DES at different time intervals from the implantation. In this study of 86 sirolimus-eluting Cypher and paclitaxel-eluting Taxus stents ISR they described different neointimal patterns and assessed their prevalence at various time intervals from DES implantation. They demonstrated that restenotic …

Transcatheter Aortic Valve-in-Valve-in-Valve Implantation for a Failed Xenograft

A 78-year-old gentleman with a diagnosis of symptomatic severe xenograft aortic stenosis with multiple comorbidities was referred for transcatheter aortic valve implantation, that is, a "valve-in-valve" procedure. Transcatheter aortic valve implantation was performed by transapical approach using a balloon-expandable bioprosthesis. During valve deployment, the prosthesis moved toward the left ventricle and a second balloon-expandable valve was implanted within the first one-a "valve-in-valve-in-valve" to avoid further ventricular embolization of the first bioprosthesis. Echocardiography at hospital discharge showed a residual mean transvalvular gradient of 17 mm Hg and trivial paravalvular aortic regurgitation. At 1 year follow-up, the patient was in New York Heart Association functional class II.

Comparison of Complete Versus Incomplete Stent Frame Expansion After Transcatheter Aortic Valve Implantation With Medtronic CoreValve Bioprosthesis

We sought to determine the significance of incomplete stent frame expansion after transcatheter aortic valve implantation with the Medtronic-CoreValve device. Incomplete coronary stent expansion is a well-described phenomenon. Transcatheter valves are mounted on stents; however, the incidence of incomplete stent expansion after transcatheter aortic valve implantation, its sequelae and predictors are poorly elucidated. The 18Fr CoreValve revalving system was used to treat anatomically and clinically suitable patients with severe calcific aortic stenosis. The postdeployment stent dimensions were measured on fluoroscopic images at multiple levels of the stent frame. Incomplete expansion at each was defined as <100% expected and complete expansion as ≥100%. These parameters were correlated to the hemodynamic and clinical end points. A total of 50 consecutive patients underwent transcatheter aortic valve implantation with the Medtronic-CoreValve at a single center from January 2007 to December 2008. For the inflow portion, incomplete expansion was seen in 54% of patients and was unrelated to the aortic valve area, peak or mean aortic valve gradients, or measures of aortic regurgitation, although it was paradoxically associated with a lower incidence of prosthesis-patient mismatch. Incomplete expansion of the constrained portion was seen in 62% of the patients and displayed a trend toward a greater incidence of aortic regurgitation grade 2 or greater, although this was rare. Incomplete expansion of the Medtronic CoreValve stent frame is common. For the most part, valvular hemodynamic function was satisfactory, regardless of the degree of expansion of the stent frame that carries it and a strategy of reluctant postdilation in the context of incomplete stent frame expansion was supported.

Complexity and simplicity in percutaneous bifurcation interventions

We read with interest the paper by Catakoglu and Aytekin describing a novel stenting technique aiming at ensuring side branch (SB) access when treating bifurcation lesions. We praise the commitment of the authors to preserve SB access, however, a few points of their strategy deserve some comments. As a first step, the authors recommend to predilate both the main vessel (MV) and the SB. Predilation of a SB without severe atherosclerotic disease is generally not recommended because of the risk of dissection and the subsequent probability to recross, through a dissection plane, a strut which is too proximal with respect to the carina. Bench testing of provisional stenting has indeed shown that rewiring through the strut closest to the carina provides a far better scaffolding than proximal rewiring. Accordingly, SB predilation is also discouraged in order to take advantage of the carina shift ensuing MV stenting so that the wire could cross the stent exactly at the carina level. In the highway technique, the incomplete stent expansion in the proximal MV due to the simultaneous inflation of a SB balloon is of concern for distal strut rewiring. Owing to stent underexpansion in the proximal MV, the stent cell which is closest to the carina is likely not facing the SB ostium, thus possibly preventing optimal SB rewiring. Just the opposite, optimisation of proximal MV stent expansion with a slightly bigger balloon (the so called POT, which stands for proximal optimisation technique) has been proposed as a mean to favour SB rewiring through the carina cell. Prior to this stage, the highway technique requires both SB balloon and SB wire to be removed. However, jailed wire removal should be avoided until effective recrossing has been performed because it marks the SB, it keeps it open and modifies favourably the angle between the two bifurcation branches. On the whole, the highway technique is a rather complex approach to improve SB access following provisional MV stenting. In the same issue of EuroIntervention, the description by Burzotta et al of the jailed balloon technique offers a far simpler approach to SB preservation when performing provisional stenting. When choosing this strategy, a balloon is just left jailed in the SB during MV stent inflation in order to reduce carina shift in addition to a favourable modification of the bifurcation angle. The jailed balloon helps rewire the SB; in case of an unsuccessful attempt, the jailed balloon may be inflated to displace the carina toward the MV, thus facilitating SB rewiring. A main concern with this technique is related to the possible risk of balloon entrapment in the SB, which, however, never happened in the authors descriptive series. In this respect, we would like to report an unexpected drawback that we encountered during our learning curve with the technique (Figure 1). Despite high pressure deployment of the MV stent, removal of its delivery catheter pulled the jailed balloon out of the SB due to friction between the stent delivery system and the shaft of the jailed balloon in the guiding catheter. We guess this harmless event could be reassuring about jailed balloon entrapment.

Transcatheter aortic valves inadequately relieve stenosis in small degenerated bioprostheses☆☆☆☆☆☆

Transcatheter aortic valves (TAVs) are a promising treatment for high risk surgical patients suffering from degeneration of previously implanted bioprostheses (valve-in-valve therapy). However, unlike native stenosed aortic valves which have accommodated Edwards SAPIEN transcatheter valves after valvuloplasty, rigid bioprostheses may prevent full TAV stent expansion and disrupt leaflet function. We hypothesized that current 23 mm TAVs would not completely relieve severe stenosis in small bioprosthetic valves. The objective of this study was to study the hemodynamics of TAVs in degenerated bioprostheses. Twelve TAVs designed to mimic the 23 mm SAPIEN valve were created. Using a pulse duplicator, hemodynamics of valve-in-valve implantation were measured within 19, 21, and 23 mm Carpentier-Edwards PERIMOUNT degenerated bioprostheses (n=6 each). Bioprosthetic degeneration was simulated using BioGlue to achieve a mean pressure gradient of 50 mmHg. TAVs significantly reduced the mean pressure gradient (50.9+/-4.7-9.1+/-4.1 mmHg, P<0.001) and total energy loss (870.3+/-157.4-307.8+/-87.3 mJ, P<0.001) in 23 mm degenerated bioprostheses. In 21 mm bioprostheses, the pressure gradient (52.3+/-7.0-19.5+/-5.0 mmHg, P<0.001) and energy loss (785.5+/-128.1-477.8+/-123.2 mJ, P=0.007) were reduced significantly. However, no significant changes in the pressure gradient (57.1+/-4.3-46.5+/-9.3 mmHg, P=0.086) or energy loss (839.3+/-49.3-960.5+/-158.1 mJ, P=0.144) were obtained after TAVI implantation in 19 mm bioprostheses. Incomplete stent expansion resulted in leaflet distortion and central regurgitation when implanted in 19 and 21 mm bioprostheses. The bioprosthetic annulus and stent posts offered a suitable landing zone for TAVs. However, oversized transcatheter valves were constrained by the rigid bioprostheses resulting in inadequate resolution of bioprosthetic stenosis. Hemodynamics of valve-in-valve intervention was worse than comparable size surgical valve replacements, particularly in 19 and 21 mm valves. Small degenerated bioprostheses require modification of current TAV design to yield acceptable hemodynamics.

Heavily Calcified Coronary Arteries: The Bane of an Interventionalist's Existence

(J Interven Cardiol 2010;23:254–255)

Can an incomplete stent expansion modulate the effects of TIPS?

We found the paper entitled TIPS for refractory ascites: a single center experience by Thalheimer et al. [1] to be of great interest, since it reports the retrospective analysis of their results obtained in patients with refractory ascites submitted to transjugular intrahepatic portosystemic shunt (TIPS) according to a protocol in which the stent used to construct the shunt was not completely expanded. The authors suggest that an incomplete stent expansion may reduce the occurrence of hepatic encephalopathy by also maintaining the efficacy of the shunt in terms of resolution of ascites. However, to test such a hypothesis, a randomized controlled trial comparing a limited versus a complete stent expansion should have been carried out. This was not the case, and, considering that the paper is a pilot study, we have some doubts regarding the methodology used and the possibility that a limited stent expansion can be useful in patients who need a TIPS. The portal pressure gradient (PPG) value that should be achieved after the stent expansion to solve the ascites and the PPG value that can avoid the occurrence of encephalopathy are in fact both unknown. It is therefore difficult to understand why the authors decided to stop the stent dilatation when the PPG reduction was more than 25%. Furthermore, we do not believe that the PPG value measured immediately after TIPS opening remains stable over time. Immediately after the procedure, in fact, the amount of blood reaching the heart increases rapidly, and a rise in the right atrium and the central venous pressure has already been described [2]. This value does not remain stable over time [3, 4]; it is therefore possible that a reduction of 25% in the PPG value measured immediately after TIPS may not be the same a few days or weeks later. We therefore wonder whether the authors have some evidence that the PPG value reached immediately after TIPS opening had remained stable over time. In addition, the authors used a self-expandable stent (Memotherm) to construct the shunt. This is an uncovered, nitinol, laser-cut stent that is no longer available in the market. It has thermal memory, which means that the nominal stent diameter expands fully when immersed in warm water. When this stent is released into a narrower liver tract, as is described by the authors in their paper, the radial force will continue to push against the surrounding liver parenchyma until the nominal size is reached. Unless the surrounding tissues are very fibrotic, this will occur in a few days. Most probably, then, although this is not specified in the paper, this type of stent continued to dilate after its initial expansion to finally reach its nominal diameter. Another issue, therefore, is whether the authors have some evidence that a partially dilated self-expandable stent is able to maintain the diameter initially reached after balloon dilatation. As a final consideration, we would like to underline that uncovered stents are presently less frequently used for TIPS creation, since the new PTFE-covered stents offer a higher patency rate and a better clinical efficacy [5, 6]. For all of these reasons, we think that the idea of modulating both the stent diameter and the PPG in TIPS construction is a good one, but randomized controlled trials comparing stents of different diameters are needed to An answer to this letter to the editor is available at doi:10.1007/s00535-009-0177-9.

Impact of intravascular ultrasound guidance in patients with acute myocardial infarction undergoing percutaneous coronary intervention

The aim of this study was to examine the utility of routine intravascular ultrasound (IVUS) guidance in patients with acute myocardial infarction (MI) undergoing percutaneous coronary intervention (PCI) with stent implantation. Stent thrombosis (ST) is a serious complication of PCI with stent implantation for patients presenting with acute MI. Mechanical factors such as incomplete stent expansion and smaller stent diameters are known to correlate with ST and restenosis. IVUS guidance for stent deployment is reported to reduce these events in stable patients. We analyzed a cohort of 905 consecutive patients who underwent primary PCI for acute MI and were discharged alive. The clinical outcomes of 382 patients who underwent IVUS-guided PCI were compared to those of 523 patients who did not. Patients who presented with cardiogenic shock and rescue PCI were excluded. The primary composite endpoint of death, MI, and target lesion revascularization at 1-year follow-up was systematically indexed and a propensity score was performed with regard to the use of IVUS-guided PCI. Patients undergoing IVUS-guided PCI were older, more diabetic and hypertensive, but presented with less history of previous MI. The severity of coronary artery disease was balanced between both groups. The number of treated lesions and stents used was higher in the IVUS-guided group, with a longer procedural duration. The overall rates of the composite primary outcome were similar (14.5% vs. 14.3%, P = 0.94) as were the rates of definite and probable stent thrombosis at 1 year (2.1% vs. 2.1%, P = 0.99) in the IVUS-guided and no-IVUS groups, respectively. After multivariate and propensity score adjustment, IVUS guidance was not an independent predictor for the primary endpoint. This study does not support the routine use of IVUS guidance for stent deployment in patients who present with acute MI and undergo primary PCI.

Membrane Degradation of Covered Stents in the Upper Gastrointestinal Tract: Frequency and Clinical Significance

To evaluate the frequency, clinical significance, and predictive factors of membrane degradation of covered stents in the upper gastrointestinal (UGI) tract. From 1996 to 2006, 166 stents were removed from 151 patients. Indications for stent removal included temporary stent placement for esophageal cancer before radiation therapy or radiation-chemotherapy (n = 53), stent migration (n = 40), temporary stent placement for a benign UGI stricture (n = 32), pain (n = 21), recurrent obstruction (n = 16), incomplete stent expansion (n = 1), recurrent transesophageal fistula (n = 2), and aspiration (n = 1). Removed stents were examined to evaluate possible causes of membrane degradation. Multivariate analysis was performed to determine the predictive factors of membrane degradation. Degradation of the covering membrane occurred in 14 of the 166 stents (8%). Recurrent obstruction due to tumor ingrowth (n = 7) and reopening of the transesophageal fistula (n = 1) through the degraded membrane occurred in eight stents (5%). At multivariate logistic regression analysis, the type of covering membrane (P = .018), stricture location (P = .006), and duration of stent placement (P = .002) were significantly associated with degradation of the covering membrane. Degradation of the covering membrane after stent placement in the UGI tract is not an uncommon event, and recurrent obstruction or fistula can occur through the degraded membrane. A polyurethane membrane is not biostable and dissolves over time, particularly in the gastroduodenal area.

Late Coronary Stent Thrombosis

Introduced >20 years ago,1 coronary artery stents have improved the safety and particularly the efficacy of percutaneous coronary interventions (PCIs).2 Abrupt vessel closure, complicating 6% to 8% of balloon angioplasty procedures, was associated with a 5% mortality, 40% rate of myocardial infarction (MI), and 40% rate of emergency coronary artery bypass grafting.3 Stents significantly reduced these adverse events (Figure 1).4,5 The reduction of restenosis afforded by bare metal stents (BMS) was modest (30% to 40%). Repeat revascularization still occurred in 15% to 20% of cases.6 Drug-eluting stents (DES) with antiproliferative drugs attached via polymers on the stent surface to minimize smooth muscle proliferation have reduced restenosis and rates of target lesion revascularization by 50% to 70% compared with BMS across nearly all lesion and patient subsets.7 Initially8 and again more recently,9–16 safety concerns were raised about DES, particularly about late stent thrombosis (ST). Figure 1. Outcome of 112 patients with abrupt vessel closure in the prestent balloon angioplasty experience of a registry (1985 to 1986; total, 1801 patients)3 and 339 patients with abrupt vessel closure during balloon angioplasty treated with BMS (Palmaz-Schatz) (total, 4596 patients).5 CABG indicates coronary artery bypass grafting. ST was a bane of stent implantation from the beginning. The initial experience with Wallstents in the late 1980s was overshadowed by ST rates approaching 24%.17 Subsequent series with Palmaz-Schatz and Gianturco-Roubin stents (still predominantly bailout stenting) observed ST in 6% to 12% of cases.4,18 The postprocedural antithrombotic regimen at the time consisted of aspirin, often in conjunction with oral anticoagulation. Dual antiplatelet therapy of aspirin and the thienopyridine ticlopidine in conjunction with a shift from bailout to elective stenting resulted in a significant reduction of ST to <2%.5,19 Earlier oral antiplatelet drug loading and …

A Rare Complication of Carotid Artery Stenting: Displacement of Marker Ring Causing Locking of Stent and Incomplete Stent Expansion

We present a rare case of a complication of placement of a carotid artery stent represented by partial opening of a carotid Wallstent caused by displacement of its metal ring marker, which thus hindered complete expansion of the stent. An intraluminally locked carotid stent necessitated referral of the patient for urgent carotid endarterectomy. A possible reason of this unusual complication can be a manufacturing defect, which, to our knowledge, was not documented previously in open public data bases or on the Internet.

A dual-design expandable colorectal stent for malignant colorectal obstruction: results of a multicenter study

It is known that metal stent placement is safe, easy, and effective for the treatment of malignant colorectal obstruction, but these stents are associated with delayed complications of tumor ingrowth and stent migration. The aim of this study was to prospectively investigate the technical feasibility, clinical effectiveness, and safety of a dual-design colorectal stent (consisting of an outer stent and an inner bare nitinol stent) in patients with malignant colorectal obstruction. Placement of the dual stent using a 4.5-mm stent delivery system was attempted in 151 patients with malignant colorectal obstruction, either before surgery (n = 50) or for palliation (n = 101). Multivariate logistic regression analysis was used to identify risk factors associated with complications. Stent placement was technically successful in 145/151 patients (96%). Of the patients who had a technically successful placement, bowel obstruction resolved within 2 days after stent placement in 48/50 (96%) of the patients in the bridge-to-surgery group and in 87/95 (92%) of the patients in the palliative group. Perforation occurred in 16 patients, incomplete stent expansion in eight patients, stent migration in four patients, tumor overgrowth in five patients, severe rectal pain in five patients, and bleeding in eight patients. Complete obstruction was the only significant risk factor for perforation (odds ratio 6.88, 95% CI 2.04-23.17, P = 0.002). In the palliative group, the median survival was 152.0 days and the mean survival was 263.8 days. The dual stent with a 4.5-mm stent delivery system is easy to insert, safe, and reasonably effective for the palliative treatment of malignant colorectal obstruction. However, a great deal of care is needed in its deployment because of the high rate of perforation.

Postmarket Surveillance for Drug-Eluting Coronary Stents

The development and introduction of new medical devices have radically changed the practice of medicine. No area of medicine has been affected more than cardiology, with new devices facilitating the effective treatment of coronary artery disease (percutaneous coronary interventions [PCIs]/stents), valvular heart disease (mechanical and bioprosthetic valves), and electrophysiological disorders (pacemakers and automatic implantable cardiodefibrillators). In addition to fueling the growth of the medical device industry, this explosion of technology has driven the development of new medical subspecialties, eg, interventional cardiology and electrophysiology. Other areas of medicine, including orthopedics and general surgery, have witnessed similar transformations. The current regulatory pathway for a significant-risk first-in-class medical device is typically a long, expensive, and risky process, culminating in a pivotal trial designed to demonstrate safety and efficacy. The pivotal trial phase is typically the most time-consuming and costly phase of the process. In the United States, medical devices are regulated by the Center for Devices and Radiological Health at the Food and Drug Administration (FDA), which has been charged by Congress to seek the “least burdensome means” when determining the scope of data required to evaluate the safety and efficacy necessary for device approval.1 Thus, pivotal trials by intention are designed to select patient cohorts most likely to demonstrate procedural benefit while limiting patient/study subject risk within the shortest time frame that can provide meaningful data. The realities of logistics, time, and resources limit the size and duration of most new device trials to 800 to 1500 patients, limiting the power of these trials to detect events with an occurrence rate of <1%. Furthermore, pivotal trials are conducted by the most experienced physician operators at medical centers with sufficient patient volume and research infrastructure to recruit and conduct clinical studies. Some have questioned whether results obtained under these settings from such …

Stent Thrombosis after Successful Drug-Eluting Stent Implantation

Background and Objectives:Stent thrombosis (ST) after a successful drug-eluting stent (DES) implantation has been reported in around 1% of clinical trials. However, the incidence of ST with a DES in practice is not well known. Here, we evaluated the possible causes of ST encountered in four Korean hospitals. Subjects and Methods:Between March 2003 and December 2003, 450 patients were treated using a DES in the four study hospitals. We reviewed the clinical and procedural characteristics of 8 patients that experienced ST after a successful DES implantation. Results:Eight patients (1.8%), who were administered antiplatelet medication, experienced ST, with a mortality of 50% at the 2 month follow-up. ST occurred within 7 days in all patients, with the exception of one, with an occurrence 37 days after intervention. Initially, all patients were diagnosed as having acute coronary syndrome. Direct PTCA was performed in 3 patients (38%). Severe calcification or a thrombus was noted in 6 (67%) of 9 lesions. In all cases, no GPIIbIIIa inhibitors were used prior to the DES implantation. Incomplete lesion coverage and incomplete stent expansion appeared in 7 (88%) cases. Conclusion:Our study demonstrated that full expansion of the DES and complete lesion coverage must be accomplished, with high pressure inflation or use of cutting balloon preferably under IVUS guidance, for the prevention of ST. Those patients with acute coronary syndrome might warrant intensive antiplatelet therapy, including GPIIbIIIa inhibitors. (Korean Circulation J 2005;35:163-171)

Removal of Retrievable Esophageal and Gastrointestinal Stents: Experience in 113 Patients

Although there are frequent clinical situations in which esophageal and gastrointestinal stents should be removed, nonsurgical stent removal has been difficult. The purpose of our study was to describe the safety and efficacy of removing the retrievable nitinol stents with a retrieval hook. Under fluoroscopic guidance, the removal of 119 esophageal, six gastroduodenal, and five rectal retrievable stents was attempted in 113 patients using a retrieval hook. Indications for stent removal included migration (n = 35), severe pain (n = 23), formation of a new stricture (n = 13), incomplete stent expansion (n = 7), airway compression (n = 2), esophagorespiratory fistula (n = 2), malpositioned stent (n = 1), and hematemesis (n = 1). The remaining 46 stents were electively removed. Of the 130 stents, 127 (97.7%) were successfully removed despite the following difficulties: untied drawstrings (n = 4), separation of the stent (n = 3), and fracture (n = 2) or disconnection (n = 2) of a retrieval hook. The removal procedure failed in three cases (2.3%). The causes of failure were the inability to place the hook into the migrated stent (n = 2) and a tight stricture above the migrated stent (n = 1). The procedure-related complications included minor (n = 4) and major (n = 1) bleeding and intramural rupture (n = 3). One patient died of major bleeding after removal of an esophageal stent. The stent retrieval hook is useful for removing retrievable esophageal and gastrointestinal stents.

1139-55 Optimal geometry is still important with sirolimus-eluting stents: Incomplete stent expansion as a risk for target lesion revascularization

1139-55 Optimal geometry is still important with sirolimus-eluting stents: Incomplete stent expansion as a risk for target lesion revascularization

Influence of stent expansion states on platelet deposition in an extracorporeal porcine arteriovenous shunt model using a multichannel perfusion chamber.

Limited data are available about incomplete stent expansion (SE) on platelet deposition (PD). We examined PD following different SE using an extracorporeal porcine arteriovenous shunt model to which a perfusion chamber with four parallel silastic tubes were connected. Blood flow was set at a 20 and 100 mL/min in 1.8 and 3.1 mm diameter tubes, respectively. P154 stents were deployed completely (Group A, n=15) or incompletely (Group B, n=15) in 1.8 mm (n=13) and 3.1 mm (n=17) tubes. 51Cr-labelled platelet autologous blood was injected 1 hr before the perfusion. After 15 min-perfusion, the testing tubes were assessed for radioactivity counts. In-stent cross sectional area was measured by intravascular ultrasound. There was a significant difference in PD between group A and B regardless of channel size (118+/-18.4 vs 261.4+/-52.1 pits x 10(6)/cm2, p<0.05). With adjusted shear rate and similar stenosis, PD was similar in both tubes. In smaller 1.8 mm tubes, a stenosis as subtle as 10% was associated with a significant PD difference (226.1+/-20 vs 112.9+/-20.5 plts x 10(6)/cm2, p<0.005). This model enabled a repetitive, simultaneous comparison of PD following different SE states. It seems that the quality of SE remains crucial in smaller channels.