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PubMed2006

In vitro evaluation of stent patency and in-stent stenoses in 10 metallic stents using MR angiography.

In vitro study to investigate the suitability of contrast enhanced magnetic resonance angiography (CEMRA) for determination of stent patency and grading of in-stent stenoses in 10 metallic stents. The Acculink carotid, DynaLink, Easy Wallstent, JostentSelfX XF, Luminexx, Omnilink, sinus-SuperFlex, SMART, Symphony and ZA stent were separately placed in a vascular phantom. Dedicated stenoses inside the stents generated a concentric lumen narrowing of 50%. CEMRA was performed for each stent. Signal loss inside the stents and artificial lumen narrowing were assessed objectively using the evaluation software of the MR imager. Moreover, three blinded observers determined visibility of stent patency and in-stent stenoses subjectively on a 3-point scale and graded in-stent stenoses. Loss of signal intensity within the stent lumen ranged between 90% (Wallstent) and 5% (ZA), artificial lumen narrowing between 56% (Symphony) and 22% (ZA). For the Symphony and Wallstent, visibility of patency and in-stent stenoses was impaired and the observers' grading exaggerated the degree of stenoses (by 23% and 33%, respectively). For the remainder of stents, patency and stenoses were visible and stenoses were graded accurately (less than 10% discrepancy from reference standard). In this in vitro study, eight of 10 stents presented with MRI characteristics which enabled determination of stent patency and accurate grading of clinically relevant in-stent stenoses.

Artifacts↗
PubMed2004

Long-term follow-up after angiographically successful coronary stenting: direct stent versus conventional stent implantation.

The purpose of the study was to compare the impacts of angiographically successful direct stent implantation and conventional stent implantation (stent implantation following predilatation) on long-term major cardiac events. The authors prospectively studied 40 patients who had successful direct stent implantation and 46 patients who had successful conventional stent implantation. The end-point of the study was defined as the occurrence of a major cardiac event, including recurrent angina, acute myocardial infarction, death, and target vessel revascularization. The demographic and clinical characteristics of the study groups were similar, except the indication of percutaneous angioplasty, which was more frequently unstable angina in the conventional stent group (63% vs 38%, P: 0.03). Procedural minor complications were more frequent in conventional stent implantation, and there was also a positive correlation between the conventional stent implantation and procedural minor complications (r = 0.231, P: 0.03), and postprocedural troponin elevation (r = 0.221, P: 0.04). The incidences of major cardiac events including recurrent angina, acute myocardial infarction, death, death or myocardial infarction, and target vessel revascularization were not different between the study groups during the long-term follow-up period (21 +/- 7.1 months for direct stent group and 20 +/- 7.5 months for conventional stent group). Overall end-points occurred in 9 patients (22%) in the direct stent group and in 9 patients (19%) in the conventional stent group. Kaplan-Meier survival analysis showed that there was no difference in event-free survival between the patients treated with direct stent implantation and conventional stent implantation (log-rank: 1.52, P = 0.21). Two-vessel intervention and hypertension were found to be related with long-term major cardiac events (r = 0.214, P: 0.048, r = 0.206, P: 0.04, respectively). In addition to the procedural advantages, direct stent implantation may also provide comparable results with conventional stent implantation concerning the late cardiac events following successful percutaneous coronary angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed2006

Sirolimus-eluting stents vs vascular brachytherapy for in-stent restenosis within bare-metal stents: the SISR randomized trial.

CONTEXT: Although vascular brachytherapy is the only approved therapy for restenosis following bare-metal stent implantation, drug-eluting stents are now being used. Data on the relative merits of each are limited. OBJECTIVE: To determine the safety and efficacy of the sirolimus-eluting stent compared with vascular brachytherapy for the treatment of patients with restenosis within a bare-metal stent. DESIGN, SETTING, AND PATIENTS: Prospective, multicenter, randomized trial of 384 patients with in-stent restenosis who were enrolled between February 2003 and July 2004 at 26 academic and community medical centers. Data presented represent all follow-up as of June 30, 2005. INTERVENTIONS: Vascular brachytherapy (n = 125) or the sirolimus-eluting stent (n = 259). MAIN OUTCOME MEASURE: Target vessel failure (cardiac death, myocardial infarction, or target vessel revascularization) at 9 months postprocedure. RESULTS: Baseline patient characteristics were well matched. Lesion length was similar between vascular brachytherapy and sirolimus-eluting stent patients (mean [SD], 16.76 [8.55] mm vs 17.22 [7.97] mm, respectively; P = .61). Procedural success was 99.2% (124/125) in the vascular brachytherapy group and 97.3% (250/257) in the sirolimus-eluting stent group (P = .28). The rate of target vessel failure was 21.6% (27/125) with vascular brachytherapy and 12.4% (32/259) with the sirolimus-eluting stent (relative risk [RR], 1.7; 95% confidence interval [CI], 1.1-2.8; P = .02). Target lesion revascularization was required in 19.2% (24/125) of the vascular brachytherapy group and 8.5% (22/259) of the sirolimus-eluting stent group (RR, 2.3 [95% CI, 1.3-3.9]; P = .004). At follow-up angiography, the rate of binary angiographic restenosis for the analysis segment was 29.5% (31/105) for the vascular brachytherapy group and 19.8% (45/227) for the sirolimus-eluting stent group (RR, 1.5 [95% CI, 1.0-2.2]; P = .07). Compared with the vascular brachytherapy group, minimal lumen diameter was larger in the sirolimus-eluting stent group at 6-month follow-up (mean [SD], 1.52 [0.63] mm vs 1.80 [0.63] mm; P<.001), reflecting greater net lumen gain in the analysis segment (0.68 [0.60] vs 1.0 [0.61] mm; P<.001) due to stenting and no edge restenosis. CONCLUSION: Sirolimus-eluting stents result in superior clinical and angiographic outcomes compared with vascular brachytherapy for the treatment of restenosis within a bare-metal stent. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00231257.

Aged↗
PubMed2002

Increased intimal hyperplasia in experimental vein graft stenting compared to arterial stenting: comparisons in a new rabbit model of stent injury.

BACKGROUND: In-stent restenosis due to intimal hyperplasia is an important clinical problem. Animal models of stent injury are limited by inconsistent arterial responses to stenting, and less intimal hyperplasia than diseased human vessels. To address these issues, we aimed to compare the degree of intimal hyperplasia in stented rabbit jugular-carotid interposition grafts (vein grafts) versus stented carotid arteries. METHODS: Jugular-carotid vein grafts were constructed in rabbits, then stented or left unstented. Carotid arteries were treated with similar stents or left instrumented only. After 3 or 28 days, vessels were perfusion fixed, embedded in resin, and sections were cut with a diamond saw. Intimal and medial thicknesses were measured in stained sections. RESULTS: After 3 days, inflammatory changes were observed in the intima of all stented vessels. After 28 days, intimal thickness in stented vein grafts was 2-fold greater than in control vein grafts and approximately 4-fold greater than in stented carotid arteries. In addition, the intimal hyperplasia response was markedly more consistent in stented vein grafts compared with stented carotid arteries. CONCLUSIONS: Stent deployment in experimental vein grafts results in increased and more reproducible smooth muscle cell intimal hyperplasia than carotid arterial stenting. This is a promising small-animal model for investigating the intimal response to stenting.

Anastomosis, Surgical↗
PubMed2006

Primary Stenting of Totally Occluded Native Coronary Arteries II (PRISON II): a randomized comparison of bare metal stent implantation with sirolimus-eluting stent implantation for the treatment of total coronary occlusions.

BACKGROUND: Sirolimus-eluting stents markedly reduce the risk of restenosis compared with bare metal stents. However, it is not known whether there are differences in effectiveness between bare metal and sirolimus-eluting stents in patients with total coronary occlusions. METHODS AND RESULTS: In a prospective, randomized, single-blind, 2-center trial, we enrolled 200 patients with total coronary occlusions: Half (n = 100) were randomly assigned to receive bare metal BxVelocity stents and half (n = 100) to receive sirolimus-eluting Cypher stents. The primary end point was angiographic binary in-segment restenosis rate at 6-month follow-up. Secondary end points were a composite of major adverse cardiac events, target vessel failure, binary in-stent restenosis rate, in-stent and in-segment minimal lumen diameter, percent diameter stenosis, and late luminal loss at 6-month follow-up. The sirolimus stent group showed a significantly lower in-stent binary restenosis rate of 7% compared with 36% in the bare metal stent group (P < 0.001). The in-segment binary restenosis rate was 11% in the group receiving a sirolimus stent versus 41% in the bare metal stent group (P < 0.0001), resulting in a target lesion revascularization rate of 4% in the sirolimus group versus 19% in the bare metal group (P < 0.001). Patients who received the drug-eluting stent also had significantly lower rates of target vessel revascularization, target vessel failure, and all major adverse cardiac events. CONCLUSIONS: In patients with total coronary occlusions, use of the sirolimus-eluting stents are superior to the bare metal stents with significant reduction in angiographic binary restenosis, resulting in significantly less need for target lesion and target vessel revascularization.

Aged↗
PubMed2001

Cost-effectiveness of coronary stenting in acute myocardial infarction: results from the stent primary angioplasty in myocardial infarction (stent-PAMI) trial.

BACKGROUND: Although several randomized trials have demonstrated that coronary stenting improves angiographic and clinical outcomes for patients with acute myocardial infarction (AMI), the cost-effectiveness of this practice is unknown. The objective of the present study was to evaluate the long-term costs and cost-effectiveness (C/E) of coronary stenting compared with primary balloon angioplasty as treatment for AMI. Methods and Results- Between December 1996 and November 1997, 900 patients with AMI were randomized to undergo balloon angioplasty (PTCA, n=448) or coronary stenting (n=452). Detailed resource utilization and cost data were collected for each patient's initial hospitalization and for 1 year after randomization. Compared with conventional PTCA, stenting increased procedural costs by approximately $2000 per patient ($6538+/-1778 versus $4561+/-1598, P<0.001). During the 1-year follow-up period, stenting was associated with significant reductions in the need for repeat revascularization and rehospitalization. Although follow-up costs were significantly lower with stenting ($3613+/-7743 versus $4592+/-8198, P=0.03), overall 1-year costs remained approximately $1000/patient higher with stenting than with PTCA ($20 571+/-10 693 versus 19 595+/-10 990, P=0.02). The C/E ratio for stenting compared with PTCA was $10 550 per repeat revascularization avoided. In analyses that incorporated recent changes in stent technology and pricing, the 1-year cost differential fell to <$350/patient, and the C/E ratio improved to $3753 per repeat revascularization avoided. The cost-utility ratio for primary stenting was <$50 000 per quality-adjusted life year gained only if stenting did not increase 1-year mortality by >0.2% compared with PTCA. CONCLUSIONS: As performed in Stent-PAMI, primary stenting for AMI increased 1-year medical care costs compared with primary PTCA. The overall cost-effectiveness of primary stenting depends on the societal value attributed to avoidance of symptomatic restenosis, as well as on the relative mortality rates of primary PTCA and stenting.

Aged↗
PubMed2002

Direct coronary stenting versus stenting with balloon pre-dilation: immediate and follow-up results of a multicentre, prospective, randomized study. The DISCO trial. DIrect Stenting of COronary Arteries.

AIMS: To assess the safety of direct coronary stenting, its influence on costs, duration of the procedure, radiation exposure, clinical outcome and angiographic restenosis. METHODS AND RESULTS: We randomized 416 patients (446 lesions) to direct stent implant or stent implant following balloon pre-dilation. Patients >75 years old, heavily calcified lesions, bifurcations, total occlusions, left main lesions and very tortuous vessels were excluded. Direct stenting was successful in 217/224 lesions (96.8%). No single loss or embolization of the stent occurred. All stents in the group with pre-dilation were effectively deployed. The immediate post-procedure angiographic results were similar with both techniques. Fluoroscopy and procedural time were significantly lower in direct stenting (6.4+/-0.3 and 21+/-0.9 min) than in pre-dilated stenting (9.1+/-0.4 and 27.5+/-1.1 min) (P>0.001). Major adverse cardiac events during hospitalization were one in direct and four in pre-dilated stenting (P=0.05) but there were no significant differences at follow-ups at 1, 6 and 12 months between the two groups. Angiographic reevaluation at 6 months was performed in 94% of the cases. Restenosis rate was 16.5% in direct stenting and 14.3% in pre-dilated stenting (P=ns). CONCLUSIONS: Direct stenting is as safe as pre-dilated stenting in selected coronary lesions. Acute angiographic results are similar but procedural costs, duration of the procedure and radiation exposure are lower in direct stenting. Overall success rate, mid-term clinical outcome and restenosis are similar with both techniques.

Adult↗
PubMed1994

Major clinical events after coronary stenting. The multicenter registry of acute and elective Gianturco-Roubin stent placement. The Gianturco-Roubin Intracoronary Stent Investigator Group.

BACKGROUND: Abrupt vessel closure and early reocclusion remain the principal vascular events underlying early recurrent ischemia complicating elective percutaneous transluminal coronary angioplasty (PTCA). Intracoronary stenting has been used to circumvent emergency bypass surgery after acute vessel closure and as an adjunct for the elective treatment of restenosis. The initial multicenter experience with the Gianturco-Roubin stent is presented, and predictors for early recurrent ischemic events are identified. METHODS AND RESULTS: Data accrued from 639 serial patients undergoing emergency stenting for abrupt closure (n = 415; 65%) or elective deployment for restenosis (n = 224; 35%) from October 1989 through May 1991 were analyzed. The incidence of subsequent ischemic events, including death, nonfatal myocardial infarction, and bypass surgery referral within 90 days of the procedure, was higher after acute deployment (20%) compared with elective stenting (9%; P = .0004). Although mortality within the two cohorts was the same (3%; P = NS), there were significant differences in the incidence of nonfatal myocardial infarction (5% versus 0.5%; P = .002) and bypass surgery (12% versus 6%; P = .02) between the acutely and electively stented patients, respectively. These events were significantly more common when the stent was undersized to the target vessel diameter (stent:artery ratio for event, 0.95 +/- 0.14 versus no event, 1.04 +/- 0.22; P = .0001) or when there was less expansion of the lesion by the deployed device (stent-to-lesion diameter ratio for event, 6.6 +/- 9.2 versus no event, 11.0 +/- 21.4; P = .0001). In a stepwise logistic regression model, acute stenting (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.3 to 2.4), multivessel disease (OR, 1.4; CI, 1.1 to 1.8), larger target lesion diameter (OR, 2.1; CI, 1.4 to 3.2), larger target vessel (OR, 2.9; CI, 1.7 to 4.7), and smaller stent size (OR, 6.1; CI, 3.0 to 12.3) were independent predictors of early, recurrent ischemic events. The presence of thrombus was associated with a higher event rate after elective stenting (OR, 2.3; CI, 1.06 to 5.4) but was not associated with a higher early event rate after acute stenting. CONCLUSIONS: Early ischemic events are more common after acute stenting for abrupt or threatened closure than after elective deployment. These events may be avoided with careful attention to morphometric characteristics to avoid undersizing the stent to the target vessel and ensure adequate lesion expansion.

Angioplasty, Balloon, Coronary↗
PubMed2004

A stent is not just a stent: Stent construction and design do matter in its clinical performance.

The undisputed superiority of stents over conventional balloon angioplasty has resulted in a plethora of stents in clinical use. Recent data, however, have indicated not all stent models are the same. Nuances in stent design and construction have impacted significantly on the immediate and long-term clinical outcome. Among the stainless steel stents, those with multicellular or tubular designs have proven to be superior to coiled or hybrid stent models, and thin-strut stents perform better than thicker-strut stents. Coating stainless steel stents with gold, carbide, phosphorylcholine or heparin do not appear to confer any additional benefit, compared with bare metal stents. In contrast, randomised trials have demonstrated that drug-eluting stents coated with various anti-proliferative drugs, with or without a carrier polymer, afford unparalleled restenosis rates compared with non-drug-eluting stents. Drug-eluting stents, however, are expensive, and their long-term durability and safety remain undefined. Notwithstanding these unresolved issues, it is likely that the majority of percutaneous coronary interventions will involve the use of drug-eluting stents once a more attractive balance between their cost and clinical effects is reached.

Angioplasty, Balloon, Coronary↗
PubMed2000

Influence of stent design on the immediate and long-term outcome after coronary stent implantation: a comparison of sinusoidal-ring and tube stents.

To evaluate the influence of stent design on the immediate and long-term outcome after coronary stent implantation, we retrospectively reviewed 151 patients (170 lesions) who underwent coronary stent implantation. The patients were divided into two groups according to the stent design, namely, the sinusoidal-ring group (GFX stent and AVE S670 stent; 64 patients, 66 lesions) and the tube group (Multi-Link stent and NIR stent; 87 patients, 104 lesions). The indication for coronary stent implantation was only provisional and additional stenting was considered in the presence of suboptimal results (residual stenosis >30%) or of a large dissection after balloon angioplasty. Angiographically confirmed success was achieved in all patients. No major adverse cardiac events were documented in either group during the hospitalization period. There were no cases of death nor of Q-wave myocardial infarction in either group during the follow-up period. The restenosis and target lesion revascularization (TLR) rates were 24.1% and 15.3% in the sinusoidal-ring group, and 20.2% and 12.6% in the tube group. respectively. The restenosis and TLR rates were similar in both groups. In conclusion, an influence of stent design on the immediate and long-term outcome after coronary stent implantation was not observed using sinusoidal-ring and tube stents.

Aged↗
PubMed2005

Stent underexpansion and residual reference segment stenosis are related to stent thrombosis after sirolimus-eluting stent implantation: an intravascular ultrasound study.

OBJECTIVES: We sought to determine the predictors of stent thrombosis after sirolimus-eluting stent (SES) implantation. BACKGROUND: A number of cases of stent thrombosis have been reported after commercial release of the SES in the "real world," such that the U.S. Food and Drug Administration issued a warning. METHODS: Fifteen patients who developed stent thrombosis after successful SES implantation were analyzed and compared with 45 matched control patients who had no evidence of stent thrombosis. RESULTS: Minimum stent cross-sectional area (MSA) (4.3 +/- 1.6 mm(2) vs. 6.2 +/- 1.9 mm(2), p < 0.001) and stent expansion (0.65 +/- 0.18 vs. 0.85 +/- 0.14, p < 0.001) were significantly smaller in the stent thrombosis group than in the matched control patients. There was no significant difference in the rate of SES malapposition between the groups. However, the presence of a significant residual reference segment stenosis was more common in the stent thrombosis group compared with the matched control group (67% vs. 9%, p < 0.001). Independent predictors of stent thrombosis were stent underexpansion (p = 0.03) and a significant residual reference segment stenosis (p = 0.02). CONCLUSIONS: Stent underexpansion and residual reference segment stenosis are associated with stent thrombosis after successful SES implantation.

Aged↗
PubMed2001

Long-term vessel response to a self-expanding coronary stent: a serial volumetric intravascular ultrasound analysis from the ASSURE Trial.A Stent vs. Stent Ultrasound Remodeling Evaluation.

OBJECTIVES: We sought to investigate the in vivo mechanical properties of a new self-expanding coronary stent (RADIUS) and, particularly, the subsequent vessel response over time. BACKGROUND: Preclinical studies have suggested that self-expanding stents may produce less vessel wall injury at initial deployment, leading to larger follow-up lumens than with balloon-expandable stents. However, the influence of the chronic stimulus from self-expanding stents on the vessel wall remains unknown. METHODS: Sixty-two patients were randomly assigned to either the RADIUS self-expanding stent group (n = 32) or the Palmaz-Schatz balloon-expandable stent group (n = 30). Intravascular ultrasound was performed after stent deployment and at six-month follow-up. RESULTS: At follow-up, the RADIUS stents had increased 23.6% in overall volume, while the Palmaz-Schatz stents had remained unchanged. Due to the greater mean neointimal area (3.0 +/- 1.7 mm2 vs. 1.9 +/- 1.2 mm2, p = 0.02) in the RADIUS group, no significant difference in net late lumen loss was observed between the two groups. On the other hand, analysis at the peristent margins demonstrated that mean late loss was significantly smaller in the RADIUS group than it was in the Palmaz-Schatz group (0.1 +/- 2.1 mm2 vs. 1.9 +/- 2.4 mm2, p = 0.02). CONCLUSIONS: Serial volumetric IVUS revealed that the RADIUS stents continued to enlarge during the follow-up period. In this stent implantation protocol, this expansion was accompanied by a greater amount of neointima than the Palmaz-Schatz stents, resulting in similar late lumen loss in both configurations. In the peristent margins, however, late lumen loss was minimized with the RADIUS stents.

Adult↗
PubMed2002

Successful repair of a damaged duodenal stent by cutting stent wires and placement of a second stent.

Duodenal stenting has been gradually established in recent years because it is less invasive than standard surgical procedures and produces a rapid therapeutic response. For palliation of both duodenal and biliary stenoses, double stenting may be performed. Duodenal stents offer a great advantage in allowing endoscopic retrograde cholangiopancreatography (ERCP) without the need for balloon dilation. When biliary stent dysfunction occurs, the patient undergoes diagnostic and/or therapeutic ERCP across the duodenal stent. We encountered a duodenal stent fracture in a patient who required repeated ERCPs for stent dysfunction. Duodenal stent fractures have not previously been reported. The damaged stent was successfully repaired by using a cutting wire filament and placing another duodenal stent coaxially with the first. Clinicians should be aware of the possibility of stent fracture following endoscopic procedures, such as an ERCP, that require passage through the stent. The procedure described in this report would be of significant benefit if a gastrointestinal stent is fractured and occluded by a broken part.

Aged↗
PubMed2000

Magnetic resonance monitoring of stent deployment: in vitro evaluation of different stent designs and stent delivery systems.

RATIONALE AND OBJECTIVES: To evaluate MR imaging features of commercially available stents before, during, and after in vitro deployment as a step toward MR-guided stent deployment. METHODS: Fourteen stents were deployed in a phantom under MR monitoring at 1.5 T by using a gradient-echo sequence. Device visibility was rated on a four-point scale (excellent, fair, poor, not visible). RESULTS: The Memotherm stent and the rolling membrane (RM) Wallstent showed excellent stent visibility and at least fair scores for artifact-induced narrowing of the stent lumen. Three stents (Palmaz, AVE, Easy Wallstent) showed excellent visibility of the stent but no visible lumen. Five stents (Strecker, Accuflex, Hemobahn, Passager, Sinus) displayed fair visibility. The delivery catheters of four stent systems (Smart, Vascucoil, Symphony, ZA) displayed severe black hole artifacts. CONCLUSIONS: The imaging features of several stent systems might be suitable for MR-guided intervention. The Memotherm and the Wallstent RM combine good visibility of the stent and the lumen.

Blood Vessel Prosthesis↗
PubMed2005

Randomized comparison of sirolimus-eluting stent versus standard stent for percutaneous coronary revascularization in diabetic patients: the diabetes and sirolimus-eluting stent (DIABETES) trial.

BACKGROUND: Outcomes after percutaneous coronary interventions in diabetic patients are shadowed by the increased rate of recurrence compared with nondiabetic patients. METHODS AND RESULTS: We conducted a multicenter, randomized trial to demonstrate the efficacy of sirolimus-eluting stents compared with standard stents to prevent restenosis in diabetic patients with de novo lesions in native coronary arteries. The primary end point of the trial was in-segment late lumen loss as assessed by quantitative coronary angiography at 9-month follow-up. The trial was stratified by diabetes treatment status. One hundred sixty patients were randomized to sirolimus-eluting stents (80 patients; 111 lesions) or standard stent implantation (80 patients; 110 lesions). On average, reference diameter was 2.34+/-0.6 mm, lesion length was 15.0+/-8 mm, and 13.1% of lesions were chronic total occlusions. In-segment late lumen loss was reduced from 0.47+/-0.5 mm for standard stents to 0.06+/-0.4 mm for sirolimus stents (P<0.001). Target-lesion revascularization and major adverse cardiac event rates were significantly lower in the sirolimus group (31.3% versus 7.3% and 36.3% versus 11.3%, respectively; both P<0.001). Non-insulin- and insulin-requiring patients demonstrated similar reductions in angiographic and clinical parameters of restenosis after sirolimus-eluting stent implantation. During the 9-month follow-up, stent thrombosis occurred in 2 patients after standard stent implantation. Conversely, this phenomenon was not seen in the sirolimus stent group. CONCLUSIONS: This randomized trial demonstrated that sirolimus stent implantation is safe and efficacious in reducing both angiographic and clinical parameters of restenosis compared with standard stents in diabetic patients with de novo coronary stenoses.

Aged↗
PubMed2002

Stent jail of the renal arteries in stent graft exclusion of AAA. An in vitro study of 3 different stent types.

BACKGROUND: The success of endoluminal stent grafts (ELG) is critically dependent on secure proximal fixation of the graft. Different types of stent grafts with uncovered proximal portions for transrenal fixation are obtainable. The present in vitro study was designed to elucidate how the flow parameters were altered by stent jail of the renal arteries with respect to different stent design. METHODS: The experiments were performed in an in vitro pulsatile circulation model. An aortic segment with bilateral side branches (like renal arteries) constructed of an ePTFE graft was perfused in the circulation model. The flow measurements were based on the ultrasound transit-time method. By varying the frequency from 30 to 100 bpm the flow parameters were altered and recorded continuously. Renal stent jailing was carried out using different stent types: Gianturco-Z-Stent, Palmaz-Stent, Powerlink Endologix. RESULTS: The flow in the aortic model increased from 1100 ml per minute to 3330 ml per minute depending on the pump frequency. In the control group without stent jail the renal flow was measured between 240 ml per minute up to 810 ml per minute. The ratio of renal flow was between 0.22 and 0.24 of the aortic flow. In the Palmaz group the ratio was between 0.21 and 0.24, in the Gianturco group between 0.23 and 0.25, and in the Powerlink group between 0.24 and 0.25 (unpaired-"t"-test: n.s.). CONCLUSIONS: The covering of the renal arteries and/ or superior mesenteric artery in case of long bared proximal stent raises the question whether the stent jail may result in flow reduction in the arteries covered or not. The present in vitro study demonstrated that the flow in the renal arteries is not decreased by these stent jails.

Aortic Aneurysm, Abdominal↗
PubMedDate not supplied

Virtual stenting of iliac arteries: a new technique for choosing stents and stent-grafts by means of 3D rotational angiography. Preliminary data.

PURPOSE: Virtual stenting (VS) is a new tool in the 3D processing work station of rotational angiography (RA) systems. This tool enables the 3D visualization of a stent or stent-graft in the site of a stenotic, obstructive or aneurysmatic lesion to be treated. We report the preliminary results obtained with this software in the treatment of segmental stenotic, obstructive or aneurysmal lesions of the iliac artery. MATERIALS AND METHODS: Seventeen patients under-went rotational angiography and 3D reformations for one or more stenoses (19 cases), obstructive lesions (2 cases) or aneurysms (2 cases) of the common and/or external iliac artery and were treated with stents in 22/23 of cases. In all cases, the VS tool was applied to the stenotic-obstructive lesion on the identified on the 3D angiogram obtained before the stenting procedure. RESULTS: The measurements of the stents/stents-grafts (length, proximal and distal diameter) provided by the tool were compared to those of the stent deployed. In 22/23 procedures, the measurements of virtual stenting and those of the deployed stent showed a good level of concordance. The system failed to provide correct measurements in only one long and tortuous iliac aneurysm. CONCLUSIONS: The ''virtual stenting'' tool proved to be reliable and fast, and enabled a more objective selection of the stent to be deployed on a stenotic-obstructive lesion in almost all cases. In cases of aneurysms of marked tortuosity, the system tends to suggest an inappropriate stent. The possibility of manually defining the optimal stent path within the aneurysmal sac might be useful.

Aged↗
PubMed1996

Wallstents versus plastic stents in malignant biliary obstruction: effects of stent patency of the first and second stent on patient compliance and survival.

OBJECTIVES: In prospective trials in patients with malignant biliary obstruction, it has been reported that Wallstents prolong stent patency, but this does not translate into a significant survival benefit. Compared with prospective trials, however, survival may be different in clinical practice because of differences in patient compliance. We report on a retrospective, long term analysis comparing Wallstents versus plastic stents. METHODS: Plastic endoprostheses (70 patients) and endoscopic Wallstents (95 patients) were placed in 165 consecutive patients with irresectable, malignant biliary obstruction in a first (1990-91) and second (1992-93) time period. Stent occlusion was treated by plastic stent placement. RESULTS: Patient characteristics were quite comparable in both stent groups. Initial placement of a Wallstent resulted in an increase of median stent patency of the first (10 vs 4 months, p < 0.001) and second (8 vs 3 months, p < 0.05) stent, a decrease of additional endoscopic procedures (20 vs 58%, p < 0.005), an increase of patient compliance reflected by a decrease of patients dying with untreated stent occlusion (9 vs 30%, p < 0.001), and an increase of survival time (6.5 vs 4 months, p < 0.05). CONCLUSIONS: Initial placement of a Wallstent results in an increase of stent patency of the first and second stent. Duration of stent patency appears to have a determinant effect on patient compliance. Increased stent patency and patient compliance seem to improve survival in clinical practice.

Aged↗