Intravascular Stent Placement Research Articles

P2Y12 inhibitors in neuroendovascular surgery: An opportunity for precision medicine.

Dual antiplatelet therapy (DAPT), primarily the combination of aspirin with a P2Y12 inhibitor, in patients undergoing intravascular stent or flow diverter placement remains the primary strategy to reduce device-related thromboembolic complications. However, selection, timing, and dosing of DAPT is critical and can be challenging given the existing significant inter- and intraindividual response variations to P2Y12 inhibitors. Assessment of indexed, peer-reviewed literature from 2000 to 2020 in interventional cardiology and neuroendovascular therapeutics with critical, peer-reviewed appraisal and extraction of evidence and strategies to utilize DAPT in cardio- and neurovascular patients with endoluminal devices. Both geno- and phenotyping for DAPT are rapidly and conveniently available as point-of-care testing at a favorable cost-benefit ratio. Furthermore, systematic inclusion of a quantifying clinical risk score combined with an operator-linked, technical risk assessment for potential adverse events allows a more precise and individualized approach to new P2Y12 inhibitor therapy. The latest evidence, primarily obtained from cardiovascular intervention trials, supports that combining patient pharmacogenetics with drug response monitoring, as part of an individually tailored, precision medicine approach, is both predictive and cost-effective in achieving and maintaining individual target platelet inhibition levels. Indirect evidence supports that this gain in optimizing drug responses translates to reducing main adverse events and overall treatment costs in patients undergoing DAPT after intracranial stent or flow diverting treatment.

Liver Transplantation Using Right Lobe Graft With Focal Nodular Hyperplasia: Report of 2 Cases

We described 2 cases of adult-to-adult liver transplantation using right lobe grafts donated by 2 patients suffering from focal nodular hyperplasia, the volumes of which were 360 cm3 and 220 cm3. This study was performed in compliance with the Declaration of the Helsinki. For preparation of the graft, back-table hepatic venous outflow reconstruction, including replacement of the retrohepatic inferior vena cava and bridging of hepatic segment V5/V8, was performed by using prosthetic vessel grafts. The liver grafts after subtracting the weight of focal nodular hyperplasia functioned well without serious small-for-size syndrome or graft dysfunction in spite of graft-to-recipient weight ratio less than 0.8%. This suggested the functioning of hepatocyte within focal nodular hyperplasia, which avoided graft deficiency. These 2 recipients were given not only conventional immunosuppressants (tacrolimus and mycophenolate sodium) but also anticoagulants (low molecular weight heparin and warfarin). Thrombosis of the prosthetic inferior vena cava 1 month after transplant in recipient 1 was treated by placement of intravascular stent. Biliary duct anastomotic stricture 2 weeks after transplant in recipient 2 was treated by placement of biliary stent. These 2 recipients remain well at more than 2 years post-transplant. These successful explorative cases highlight the safe use of a graft containing focal nodular hyperplasia. The partial liver resection grafts with focal nodular hyperplasia could be applied to the patients on the waiting list for liver transplantation.

Percutaneous Costoclavicular Bypass for Thoracic Outlet Syndrome and Cephalic Arch Occlusion in Hemodialysis Patients.

To report results of percutaneous costoclavicular bypass for symptomatic thoracic outlet or cephalic arch occlusion in patients with arteriovenous fistula. A retrospective review of percutaneous costoclavicular bypass patients between 2014 and 2018 was performed. Stent grafts were placed subcutaneously over the clavicle from the fistula outflow (axillary or cephalic vein) into a jugular vein or collateral. The procedures were performed in patients who had exhausted or were not candidates for balloon dilation or intravascular stent placement. Technical success was 100% (9/9) with resolution of symptoms in all patients. Indications were arm swelling in 67% (6/9), fistula dysfunction in 22% (2/7), and 1 enlarging aneurysm. The fistula outflow was cephalic in 67% (6/9) and axillary in 33% (3/9). The return vessel was external jugular in 78% (7/9) and internal jugular in 22% (2/9). Two overlapping Viabahn stent grafts were used in 88% of cases (7/8) and 3 stent grafts in 1 case. In the initial case, 2 Gore hybrid grafts were used. Stent graft diameter ranged from 9 mm to 13 mm. Mean follow-up was 852 ± 339 days (range, 488-1483 days). At 12 months and 24 months, primary patency was 67% and 67%, and secondary patency was 89% and 78%, respectively. Complications included late thrombosis and secondary infection. There were no anastomotic leaks or seromas associated with extravascular stent grafts. The percutaneous costoclavicular bypass is a feasible option for thoracic outlet and cephalic arch occlusion in symptomatic dialysis patients.

Hyperbilirubinemia Due to Extrinsic Biliary Compression From Direct Intrahepatic Portocaval Shunt Performed for Portal Hypertensive Bleeding

Direct intrahepatic portocaval shunt (DIPS) is a procedure involving intravascular stent placement through the caudate lobe of the liver for management of portal hypertension. It is employed less frequently than TIPS, and extrinsic biliary compression due to DIPS has never been described in the literature. A 65 year old female with history of non-cirrhotic fibropolycystic liver disease and PVT with cavernoma and sinistral portal hypertension underwent DIPS and ileal variceal embolization for massive ileal variceal bleeding. TIPS was attempted but unsuccessful, so DIPS was subsequently performed. Pre-procedural alkaline phosphatase (AP) was 56U/L, total bilirubin (TB) 1.1mg/dL, and direct bilirubin (DB) was 0.4mg/dL. Post-procedurally she was noted to have AP 326U/L, TB 9.8mg/dL, and DB 6.9mg/dL. There was report of dark stools, with initial concern of hemobilia versus bilhemia. Imaging revealed stable mild intrahepatic and common bile duct (CBD) dilatation. Given new fevers and possible enhancement of CBD, she was treated with piperacillin-tazobactam for presumed cholangitis with subsequent improvement and was discharged home. She returned ten days later with alkaline phosphatase of 2,925U/L with total bilirubin of 41.9mg/dL and direct bilirubin of 29.8mg/dL. MRI revealed intra- and extra-hepatic biliary dilatation to the mid-CBD felt to be due to extrinsic compression by the crossing DIPS. ERCP revealed CBD stenosis which did not appear to be related to crossing DIPS but was stented. Afterwards, her AP peaked at 3,062U/L with TB 56.9mg/dL and DB 38.1mg/dL. Liver biopsy revealed bland cholestasis. Her liver chemistries started to improve. Due to persistent fevers, ERCP was repeated for stent exchange and revealed sigmoid-shaped stenosis in the upper CBD due to extrinsic compression from the crossing DIPS, thus revealing the ultimate diagnosis. Stent was replaced and AP subsequently improved to 104U/L with TB 1.4mg/dL.The differential of hyperbilirubinemia after DIPS procedure includes hemolysis (typically presents with indirect hyperbilirubinemia), as well as hepatic decompensation (increase in all liver chemistries), bilhemia from biliary-venous fistula (isolated hyperbilirubinemia), infection (often a mixed picture), and biliary compression (cholestatic picture). This complicated case illustrates the difficulty in diagnosis of extrinsic biliary compression in a patient with known mild biliary dilation, requiring a second ERCP to make the final diagnosis.2187_A Figure 1. MRCP image of the 1.9 cm segmental narrowing of the mid common bile duct, thought to be related to the crossing DIPS.2187_B Figure 2. MRCP image of 1.9cm segmental narrowing of CBD secondary to extrinsic compression by the crossing TIPS

Intravascular and hybrid intraoperative stent placement for baffle obstruction in transposition of the great arteries after atrial switch.

To report our experience with intravascular and hybrid intra-operative stent placement for baffle obstruction in patients with complete transposition of the great arteries (TGA) after the atrial switch (Mustard/Senning) operation. Venous baffle obstruction is a challenging complication after atrial switch operation in patients with TGA. Traditional treatment options include intravascular stenting or surgery. A retrospective analysis of Mayo Clinic's electronic medical record was completed to identify consecutive pediatric and adult patients with TGA after atrial switch who underwent baffle stent implantation from 1994 to 2015. Overall, 64 patients were referred for cardiac catheterization, in whom 47 (73%) were noted to have hemodynamic and angiographic evidence of baffle obstruction. A total of 20 patients mean age 33 (range: 8-46) years old underwent stent implantation of baffle stenosis at a mean of 33 (range: 7.5-45) years after initial atrial switch operation (Mustard, n = 19; Senning, n = 1). Overall, 27 baffles were stented in 20 patients via the following approaches: intravascular (17); hybrid surgical (3); staged intravascular & hybrid (2). Sites of stent placement were: superior vena cava (SVC) (13); inferior vena cava (IVC) (9); pulmonary venous baffle (5). Three patients had stent placement in the SVC and IVC baffles during the same procedure. Procedural adverse events occurred in 2/22 cases (9%) including creation of unintentional baffle leak (n = 1) and stent migration (n = 1). There was no procedure-related mortality. At follow-up (median 2, range 0.02-10 years), significantly improved NYHA class and mean Doppler baffle gradient were demonstrated (P < 0.05). Mild baffle re-stenosis (mean Doppler gradient; 2-3 mmHg) occurred in two patients who have not required re-intervention. Trivial baffle leak was noted in four patients. Baffle re-intervention was only occurred in one patient. One patient with pre-procedural Class IV symptoms died 3.5 months after stent implantation. This study is the largest reported experience of intravascular and intra-operative hybrid stent placement for patients with TGA after atrial switch. Transcatheter and minimally invasive hybrid intraoperative surgical stent placement are an effective strategy for relief of systemic and pulmonary venous baffle obstruction. © 2016 Wiley Periodicals, Inc.

Outcomes of Cephalic Arch Stenosis With and Without Stent Placement after Percutaneous Balloon Angioplasty in Hemodialysis Patients

Cephalic arch stenosis is a common complication in maintenance hemodialysis (MHD) patients with brachial artery-cephalic vein fistulas and frequently leads to loss of the functioning brachial artery-cephalic vein fistula. There is paucity of conclusive data to guide appropriate management. We examined the risk of recurrence of cephalic arch stenosis after angioplasty compared to angioplasty after stent placement determined by angiography of the involved upper extremity over time in a contemporary cohort of MHD patients treated in two interventional nephrology practices from March 2008 through May 2011. We retrospectively identified 45 MHD patients with evidence of cephalic arch stenosis (age 60 ± 30 years, 45% men) on elective angiograms. The median number of days until another angioplasty was required decreased, starting with a median of 91.5 days after the first, 70.5 days after the second, 85 days after the third, and 56 days after the fourth. Angioplasty is associated with a faster rate of recurrence of cephalic arch stenosis. The placement of intravascular stent seems to prolong the patency compared to angioplasty alone. Clinical trials with a larger sample size will better elucidate the value and timing of angioplasty versus stent placement in cephalic arch stenosis.

Prasugrel is effective and safe for neurointerventional procedures

BackgroundClopidogrel bisulfate and aspirin are routinely administered as dual antiplatelet agents for many neurointerventional procedures, especially for intravascular stent placement. Many patients are non-responsive to clopidogrel, either secondary to drug...

Abstract 2764: Assessment Of Intravascular Ultrasonography Assisted Aneurysm Coil Embolization

Background: Intravascular ultrasonography (IVUS) has been previously used for guiding intravascular stent placement in interventional cardiology. Objective: To evaluate the feasibility of aneurysm embolization using detachable coils under IVUS guidance. Method: Two different experimental models of aneurysm were used. IVUS guided embolization in conjunction with flouroscopic imaging and subsequently alone were performed in a silicone model with a side wall aneurysm. IVUS guided embolization in conjunction with flouroscopic imaging was also used in in-vitro model of side wall aneurysm created using sheep vessels. The visibility of aneurysm, microcatheter, and coils ascertained by the IVUS was graded as excellent, good, or poor based on visualization of these items as distinct structures. The agreement between simultaneously acquired angiographic and IVUS images for detecting increasing intra-aneurysmal coil mass and coil prolapse was assessed in 10 and 6 simultaneously acquired angiographic and IVUS images, respectively. Results: IVUS measurements of the aneurysm dimensions strongly correlated with actual dimensions and measurements acquired by contrast angiography (Pearson’s coefficient of 0.96 and 0.99 for silicone model and arterial segment model, respectively) ( Figure 1 ). IVUS visualization of aneurysm, microcatheter tip, and coil loops were graded as excellent in the silicone aneurysm model and good in carotid artery model ( Figure 2 ). The agreement between simultaneously acquired angiographic and IVUS images was very high, for detecting increasing intra-aneurysmal coil mass (Spearman’s rank correlation coefficient of 0.98) and coil prolapse (83% agreement). We were able to successfully perform and complete embolization of silicone aneurysm model with IVUS alone (complete obliteration confirmed by direct visualization). Conclusion: This study shows IVUS-guidance during aneurysm embolization may improve the procedure by providing intravascular aneurysmal measurements and visualization of devices used in the procedure.

Aneurysm Embolization Using Detachable Coils Under Intravascular Ultrasonography Guidance

Intravascular ultrasonography (IVUS) has been used for guiding intravascular stent placement in interventional cardiology. To evaluate the feasibility of aneurysm embolization by using detachable coils under IVUS guidance. IVUS-guided embolization in conjunction with fluoroscopic imaging and subsequently alone were performed in a silicone model with a side wall aneurysm. IVUS-guided embolization in conjunction with fluoroscopic imaging was also used in an in vitro model of a side wall aneurysm created using sheep vessels. The visibility of the aneurysm, microcatheter, and coils ascertained by the IVUS was graded as excellent, good, or poor based on visualization of these items as distinct structures. The agreement between simultaneously acquired angiographic and IVUS images for detecting increasing intra-aneurysmal coil mass and coil prolapse was assessed in 10 and 6 simultaneously acquired angiographic and IVUS images, respectively. IVUS measurements of the aneurysm dimensions strongly correlated with standardized dimensions and measurements acquired by contrast angiography (Pearson coefficient of 0.96 and 0.99 for silicone model and arterial segment model, respectively). IVUS visualization of the aneurysm, microcatheter tip, and coil loops were graded as excellent in the silicone aneurysm model and good in the carotid artery model. The agreement between simultaneously acquired angiographic and IVUS images was very high for detecting increasing intra-aneurysmal coil mass (Spearman rank correlation coefficient of 0.98) and coil prolapse (83% agreement). IVUS guidance during aneurysm embolization may improve the procedure by providing intravascular aneurysmal measurements and visualization of devices used in the procedure.

The safety of clopidogrel

Importance of the field: Clopidogrel is an antiplatelet prodrug widely used in acute coronary syndromes and after intravascular stent placement. Acute or chronic use can cause bleeding, a major adverse effect, which can lead to drug discontinuation or noncompliance with therapy.Areas covered in this review: The mechanism of action of clopidogrel, safety of different loading doses of clopidogrel, its use as a solitary antiplatelet agent and concomitant use with other antiplatelet agents such as aspirin and warfarin are discussed. Thrombotic thrombocytopenic purpura, a rare but important adverse event, has also been reviewed. Literature searches including randomized controlled trials were conducted in Medline.What the reader will gain: Clinicians will be able to understand the safety profile of using different doses of clopidogrel and the incidence of bleeding when used alone or in combination with other antiplatelet agents.Take home message: Compared to aspirin, clopidogrel when taken alone causes less severe bleeding and less intracranial hemorrhage. Higher loading dose of clopidogrel is associated with increased bleeding. When combined with other antiplatelet agents, risk of bleeding increases, but like any other drug, the risks have to be weighed against potential benefits.

TCT-41: Intravascular Ultrasound-Guided Drug-Eluting Stent Placement is Associated with Reduced Incidence of Recurrent Clinical Events (Death or MI)

TCT-41: Intravascular Ultrasound-Guided Drug-Eluting Stent Placement is Associated with Reduced Incidence of Recurrent Clinical Events (Death or MI)

経皮的腎動脈形成術(PTRA)が著効した腎動脈狭窄症(RAS)による慢性腎不全の2例

We describe here two cases of renal artery stenosis(RAS) caused by atherosclerosis. Both patients were treated by percutaneous transluminal renal angioplasty(PTRA) and stent placement, leading to the improvement of renal function as well as hypertension. The two patients were a 75-year-old male(case 1) and a 56-year-old male(case 2), who both showed mild proteinuria, renal dysfunction, and refractory hypertension. Case 1 showed a unilateral ostial stenosis in the left main renal artery. On the other hand, case 2 showed an ostial stenosis in the left renal artery and a widespread narrowing in the right renal artery. After evaluation of the lesions by renal Doppler sonography, renogram, magnetic resonance signal intensity, and magnetic resonance angiography(MRA), each stenosis was treated by balloon angioplasty and intravascular stent placement without any major complications. Thereafter, in addition to hypertension, renal function also ameliorated significantly, and has remained stable for more than 12 months. Non-invasive screening tests and appropriate therapy for renovascular lesion should be considered in the case of elderly patients with refractory hypertension and progressive renal dysfunction, since ischemic nephropathy is increasing as a common cause of end stage renal disease and is showing favorable outcomes of revascularization.

A link between stent radial forces and vascular wall remodeling: The discovery of an optimal stent radial force for minimal vessel restenosis

Coronary and peripheral artery disease (PAD) continue to be primary causes of morbidity and mortality in western nations; percutaneous transluminal angioplasty (PTA) with stenting has become a popular treatment. Unfortunately, restenosis is a significant problem following intravascular stent placement. This study considers the contribution of stent forces in vascular stenosis and remodeling to develop an equation for identifying the optimal stent force. z-Type stents of three radial forces [low (3.4 N), high (16.4 N), and ultrahigh (19.4 N)] were deployed into the iliac arteries of a juvenile porcine model. Vessel diameters were measured before, after deployment, and again at 30 days. At 30 days animals were killed and the vessels fixed in situ. After implantation, there was a significant increase in total thickness and neointimal hyperplasia with increasing stent force. The model for vessel radius and experimental data was in agreement. The model shows that maximum late‐term radius is achieved with a stent deployment stress of 480 kPa, which occurs at the end of the stress–strain curve nonlinear domain and beginning of the high-strain collagen domain. The results and calculations suggest that an optimal stent force exists that is subject to the geometry, structure, and mechanics of the target vessel. To achieve maximum late-term dilatation, stents should not produce stress in the vessel wall greater than the end of the transitional domain of the vessel's stress–strain curve. This finding is extremely important for vascular stent development and will be expanded to preliminary vessel wall injury and atherosclerotic models.

Impact of diabetes mellitus on in-hospital death of patients with acute myocardial infarction.

Objective To evaluate the clinical characteristics and in-hospital mortality of acute myocardial infarction patients (AMI) with diabetes mellitus (DM) and to analyze the risk factors of in-hospital mortality of AMI. Method A total of 1023 patients with diagnosis of AMI complicated with or without DM admitted between 2000 and 2004 were analyzed to find out the clinical characteristics, in-hospital complications and mortality. Of them, 164 (16.03%) were complicated with DM. The data were analyzed by using Mann-Whitney U or chi-square test. The multivariate logistic regression analysis was used to find out the risk factors of in-hospital mortality of patient with AMI. Results In comparison with non-DM patients, the females were predominant in number over males in the DM patient cohort (42.2% vs. 28.9%, P < 0.05), the incidence of hypertension (71.7% vs. 41.6%, P < 0.01) and rate of angina (57.3% vs. 48.3%, P < 0.06). The admission time of DM patients was delayed rather than that of non-DM patients. Coronary angiography revealed that the rate of three-vessel in-volved was higher in DM patients than in non-DM patients (48.4% vs. 25.4%, P < 0.05. During hospital stay, AMI patients with DM presented mar frequently with arrhythmias, pulmonary edema (18.9% vs. 10.5%, P <0.01) and increase in in-hospital mortality (17.7% vs. 9.2%, P < 0.01) compared with non-DM patients. Di-uretics (43.9% vs. 32%, P <0.01) and digitalis (27.4% vs. 16.8%, P <0.01) were more frequently used in DM patients rather than in non-DM patients. Compared to medication, primary coronary intervention (PCI) with placement of intra-vascular stent significantly decreased the mortality of DM patients (χ~2 = 4.536, P < 0.05).Logistic regression analysis showed DM was an independent risk factor for in-hospital mortality (OR = 2.109;95% CI:1.229-3.619). Conclusions AMI patients with DM exhibit more risk factors for in-hospital complications and higher mortality than those without DM.DM is an independent risk factor for in-hospital mortality of patients with AMI. Key words: Myocardial infarction; Diabetes mellitus; in-hospital mortality; Prognosis; Multiple factors analysis

Results of Intravascular Stent Placement for Fibrosing Mediastinitis

Fibrosing mediastinitis is a rare disorder characterized by an excessive fibrotic reaction in the mediastinum which can result in compromise of mediastinal structures. We sought to evaluate short- and midterm results of intravascular thoracic vessel stent placement for patients with fibrosing mediastinitis. We reviewed all records of fibrosing mediastinitis patients who were referred for stent placement to treat mediastinal vascular compression over a 7-year period. Catheterization reports and digital angiography were assessed to determine vessel dimension and stent characteristics. Thirteen catheterizations were performed in six patients (five females, mean age 39 years, range 23-63) with a range of 1-4 per patient. Four patients were treated with intravascular stents placed percutaneously. One patient underwent surgical intravascular stent placement, and one patient declined surgical therapy. The right pulmonary artery was treated in three patients, the superior vena cava was treated in one patient, and three pulmonary veins were treated in one patient. Pertinent vessel and hemodynamics including immediate short-, and mid-term results were assessed. Procedural complications, midterm follow-up (up to 7 years), and overall survival were determined. Each intervention resulted in hemodynamic improvement with subsequent clinical improvement. Reintervention was required within 12 months in two of four percutaneously treated patients. One death occurred 4 days after cutting balloon angioplasty in a preexisting pulmonary vein stent. Percutaneous therapy for vessel compression secondary to fibrosing mediastinitis is an option that is effective in improving short-term vascular patency. In-stent stenosis was a frequent complication in patients with fibrosing mediastinitis, particularly when pulmonary veins were involved. Short- and midterm success can be achieved, but progressive fibrosing mediastinitis remains a difficult clinical problem with repeat dilation of stents and/or additional stent placement necessary to maintain optimal stent patency and improvement in clinical symptomatology.

Stent salvage for parent vessel coil herniation during intracranial aneurysm embolization

Background: Despite accumulated experience and improved understanding of the tools, endovascular treatment of cerebral aneurysms still has risks associated with the technique itself and with the specificity of the pathology treated. An important risk is parent vessel Guglielmi detachable coil herniation. Here we review and illustrate our experiences in using a stent to manage this complication.Methods: We reviewed our experiences in 142 intracranial aneurysm embolizations over a four and a half year period and identified 13 cases with intravascular stent deployment. Three cases were unique in using a stent for salvage of coil herniation into the parent vessel.Results: We reported these cases and reviewed the literature for the management of parent vessel coil herniation.Conclusion: Parent vessel coil herniation was an uncommon but important complication of endovascular coiling of intracranial aneurysm. Intravascular stent placement provided a tool to sequester herniated coils from the lumen of the parent artery to minimize thromboembolic complications and restore flow.

Stent Placement in Hemodialysis Access

Vascular access stenosis in patients undergoing chronic hemodialysis is a major issue that is associated with increased morbidity, mortality, and cost of medical care. Recent data have emphasized that endovascular stents could be used in the treatment of central as well as peripheral stenotic lesions. In general, a peripheral or central vein lesion that is elastic or recurs within a three-month period after an initially successful balloon angioplasty or a stenosis where surgical revision is not possible are some indications for intravascular stent placement. Recent reports have expanded the role of stents in the management of pseudoaneurysms associated with dialysis access. In this context, the utilization of these devices must take into account a fair comparison with the traditional (surgical) approaches regarding effectiveness as well as costs. This report describes the role of stents in arteriovenous dialysis access. In addition, some of the recent advances in the structure and complicating issues such as stent fracture, migration, and infection, as well cannulation through the stent, are discussed.

A Randomized Controlled Trial of Angiography Versus Intravascular Ultrasound-Directed Bare-Metal Coronary Stent Placement (The AVID Trial)

AVID (Angiography Versus Intravascular ultrasound-Directed stent placement) is a multicenter, randomized controlled trial designed to assess the effect of intravascular ultrasound (IVUS)-directed stent placement on the 12-month rate of target lesion revascularization (TLR). After elective coronary stent placement and an optimal angiographic result (<10% stenosis), 800 patients were randomized to Angiography- or IVUS-directed therapy. Blinded IVUS was performed in the Angiography group without further therapy. In the IVUS group, IVUS criteria for optimal stent placement (<10% area stenosis, apposition, and absence of dissection) were applied. Final minimum stent area was 6.90+/-2.43 mm(2) in the Angiography group and 7.55+/-2.82 mm(2) in the IVUS group (P=0.001). In the IVUS group, only 37% with inadequate expansion (<90%) received further therapy. The 12-month TLR rate was 12.0% in the Angiography group and 8.1% in the IVUS group (P=0.08, 95% confidence level [CI], [-8.3% to 0.5%]). When vessels with a distal reference diameter <2.5 mm by core laboratory angiography measurement were excluded from analysis, the 12-month TLR rate was 10.1% in the Angiography group and 4.3% in the IVUS group (P=0.01, 95% CI, [-10.6% to -1.2%]). With a pre-stent angiographic stenosis of > or =70%, the TLR rate was lower in the IVUS group compared with the Angiography group (3.1% versus 14.2%; P=0.002; 95% CI, [-18.4% to -4.2%]). IVUS-directed bare-metal stent placement results in larger acute stent dimensions without an increase in complications and a significantly lower 12-month TLR rate for vessels > or =2.5 mm by angiography and for vessels with high-grade pre-stent stenosis. However, for the entire sample analyzed on an intention-to-treat basis, IVUS-directed bare-metal stent placement does not significantly reduce the 12-month TLR rate when compared with stent placement guided by angiography alone. In addition, IVUS evaluation of adequate stent expansion is underutilized by experienced operators.

Comparison of vasa vasorum after intravascular stent placement with sirolimis drug‐eluting and bare metal stents

The cytostatic drug, sirolimis has shown prevention in neointimal hyperplasia after stent placement. Recent studies have shown persistent inflammation seen with drug-eluting stents (DES) may result in late stent thrombosis. The aim of this study is to compare effects of bare metal stents (BMS) and sirolimis DES on the neointima and vasa vasorum in stented rabbit aortas. Stents were implanted in eight New Zealand rabbits for 9 weeks. Group I rabbits received BMS. Group II rabbits received sirolimis DES. A balloon-mounted BMS or DES was placed in the infrarenal aorta. Following euthanasia, aortas were perfused with barium sulfate and sectioned for histology. After 9 weeks the qualitative intrastent luminal diameter was fairly uniform in both the DES and the BMS. The thickness of neointima was similar in both groups. The number of vasa vasorum in the sirolimis DES increased compared with the BMS (P < 0.05). An increased number of vasa vasorum produced by the DES when compared with the BMS shows a difference in response to local vessel injury in rabbits. This result suggests that vasa vasorum may play a role in the persistent inflammation generated by sirolimis-coated stents.

Endovascular Interventions of Juxtaanastomotic Stenoses and Thromboses of Hemodialysis Arteriovenous Fistulas

To assess the primary and secondary patency rates for juxtaanastomotic stenoses, with or without superimposed thromboses, of arteriovenous hemodialysis fistulas treated with angioplasty and to compare it with National Kidney Foundation Dialysis Outcomes Quality Initiative treatment guidelines for stenosed and occluded arteriovenous fistulas (50% primary patency rate at 12 months). This study was a retrospective analysis, covering a period of 5(1/2) years. Forty-three hemodialysis patients were referred due to secondary fistula dysfunction, and angiography was diagnostic of a juxtaanastomotic lesion. Interventions consisted of standard angioplasty techniques along with thrombolysis and/or thrombectomy and intravascular stent placement as needed. Follow-up was performed at the attending dialysis center, and repeat angiography was performed as clinically required. Immediate postprocedural angiography demonstrated an angiographic success rate of 98%. Clinical success, with at least one session of normal dialysis, occurred in 95% of interventions. Primary patency rates at 12 months for the stenosed and stenosed/thrombosed fistulas were 56% and 64%, respectively. Secondary patency rates at 12 months were 64% and 63%, respectively. Half of the stenosed fistulas were patent at 1.5 years, 28% were patent at 4 years, and 13% remained patent at 6 years. No major complications were documented. Four minor complications, which did not require therapy, were noted. The results achieved are comparable to those reported for interventions at nonjuxtaanastomotic sites and exceed those quoted by the National Kidney Foundation Dialysis Outcomes Quality Initiative guidelines. Angioplastic interventions in a juxtaanastomatic area of arteriovenous fistulas are safe, promote prolonged patency, and postpone the need for surgical intervention or creation of a new fistula.