Stent Apposition Research Articles

Optical Coherence Tomography as an Adjunct During Carotid Artery Stenting for Carotid Atherosclerotic Disease.

Carotid artery stenting (CAS) has been proven to decrease the risk of stroke in symptomatic patients with moderate/high-grade carotid stenosis; however, there is an increased periprocedural risk of stroke with CAS compared to carotid endarterectomy. The goal of this article is to report the utilization of endovascular optical coherence tomography (OCT) during CAS to aid in the identification of stent malapposition, plaque prolapse, and adjacent residual thrombus that could cause periprocedural stroke. Approval was obtained for endovascular OCT imaging in patients undergoing CAS. Images were obtained before and after stenting. Images were acquired with proximal balloon occlusion and saline to clear luminal blood during acquisition. Atotal of seven patients provided informed consent for imaging. There were no complications during image acquisition or the stenting procedure. Optical coherence tomography imaging revealed free intraluminal red thrombi, fibrous cap dissections, and thin cap fibroatheromas with underlying ulcerative plaques. Plaque herniation through stents was also demonstrated along with thrombus. Poor stent apposition was clearly visible. Optical coherence tomography image acquisition was found to be safe, effective, and to provide valuable information about plaque morphology and stent-vessel interactions. The role of perioperative anticoagulation after stenting should be re-evaluated given the new findings. Astudy comparing CAS with and without OCT with aclinical primary outcome such as ipsilateral stroke could help determine if OCT is an innovative tool to guide stenting and antithrombotic management.

Morphologic performance analysis of the Relay nonbare stent graft in dissected thoracic aorta

ObjectiveThe aim of this study was to evaluate morphologic changes in dissected aortas after thoracic endovascular aortic repair (TEVAR) with the use of the Relay Nonbare stent graft stent graft by focusing on the geometric stent graft's performance in remodeling aortas. MethodsWe conducted a retrospective three-dimensional computed tomography analysis preoperatively, postoperatively, and 6 months after TEVAR in patients with residual dissection after type A and those with acute and chronic type B dissections at two German centers. ResultsThirty-nine acute and 54 chronic aortic dissections were included. Median follow-up was 200 (interquartile range, 109-617) days. TEVAR induced aortic remodeling in both groups. Complete false lumen thrombosis along the stent graft (postoperative, 73%; follow-up, 84%; P < .0001) led to a decrease in aortic diameter at the middle stent graft level (preoperative, 45.9 mm [38.6-56.6] vs follow-up, 43.6 [37.4-52.4] mm; P = .009). True lumen expansion was observed in both groups and peaked in acute dissections in the distal landing zone (acute, +9.3 mm vs chronic, +5.8 mm; P < .0001). Migration was 2 (0-5) mm, and bird-beak and endoleak type IA rates were 20% and 4%, respectively. There was no retrograde type A dissection. Distal stent graft-induced new entry occurred in 15%; the major risk factor for incidence was the stent graft's wedge apposition angle (odds ratio, 1.365 [confidence interval, 1.115-1.671]; P = .003). ConclusionsTEVAR with the use of the Relay NBS promotes aortic remodeling in acute and chronic dissections, entailing a low risk of migration, type IA endoleaks, and retrograde type A dissections. Wedge apposition was the predominant risk factor for distal stent graft-induced new entry.

Automated stent coverage analysis in intravascular OCT (IVOCT) image volumes using a support vector machine and mesh growing.

Absence of vascular-stent tissue coverage by IVOCT is a biomarker for potential stent-related thrombosis. We developed highly-automated algorithms to classify covered and uncovered struts and quantitatively evaluate stent apposition. We trained a machine learning model on 7,125 images, and included an active learning, relabeling step to improve noisy labels. We obtained uncovered strut classification sensitivity/specificity (94%/90%) comparable to analyst inter-and-intra-observer variability and AUC (0.97), and tissue coverage thickness measurement arguably better than the commercial product. By comparing classification models from regular and relabeled data sets, we observed robustness of the support vector machine to noisy data. A graph-based algorithm detected clusters of uncovered struts thought to pose a greater risk than isolated uncovered struts. The software enables highly-automated, objective, repeatable, comprehensive stent analysis.

Numerical Study of Incomplete Stent Apposition Caused by Deploying Undersized Stent in Arteries With Elliptical Cross Sections.

Incomplete stent apposition (ISA) is one of the causes leading to poststent complications, which can be found when an undersized or an underexpanded stent is deployed at lesions. The previous research efforts have focused on ISA in idealized coronary arterial geometry with circular cross section. However, arterial cross section eccentricity plays an important role in both location and severity of ISA. Computational fluid dynamics (CFD) simulations are carried out to systematically study the effects of ISA in arteries with elliptical cross section, as such stents are partially embedded on the minor axis sides of the ellipse and malapposed elsewhere. Overall, ISA leads to high time-averaged wall shear stress (TAWSS) at the proximal end of the stent and low TAWSS at the ISA transition region and the distal end. Shear rate depends on both malapposition distance and blood stream locations, which is found to be significantly higher at the inner stent surface than the outer surface. The proximal high shear rate signifies increasing possibility in platelet activation, when coupled with low TAWSS at the transition and distal regions which may indicate a nidus for in-stent thrombosis.

STENT EXPANSION AND ENDOTHELIAL SHEAR STRESS IN BIFURCATION LESION: COMPARISON OF KISSING BALLOON INFLATION AND PROXIMAL OPTIMIZING TECHNIQUE

Treatment of bifurcation lesions remains technically challenging for interventional cardiologists. Previous idealized in vitro bench models have shown that kissing balloon inflation (KBI) might result in a less circular stent shape, worse stent apposition and lower endothelial shear stress (ESS)

Experimental investigation of influence of stent designs and sizes on stent apposition using a left main coronary artery bifurcation model

Experimental investigation of influence of stent designs and sizes on stent apposition using a left main coronary artery bifurcation model

Intravascular ultrasound-guided internal carotid artery stenting.

The study was aimed at demonstrating efficacy and feasibility of intravascular ultrasound during internal carotid artery stenting for assessment of atheromatous plaque protrusion through a stent. Over the period from October to December 2018, the specialists of our Centre performed a total of 90 internal carotid artery stenting procedures in 83 patients (of these, 7 patients underwent bilateral staged stenting of both internal carotid arteries) using intravascular ultrasound in order to assess intraoperative protrusion of an atherosclerotic plaque through the implanted stent. The patients' age varied from 42 to 87 (mean 68.6±6.9) years. Symptomatic lesions of internal carotid arteries were revealed in 14 (16.9%) operated patients and asymptomatic lesions in 69 (83.1%). The degree of stenosis varied from 60% to 90% according to the findings of preliminary duplex ultrasonography and was subsequently confirmed by the results of multislice computed tomography or selective angiography. The assessment of the patients' neurological status, as well as duplex ultrasonography of brachiocephalic arteries were performed at a scheduled follow-up visit on day 30 after discharge from hospital. The technical success of stenting was achieved in 100% of patients. According to the findings of intravascular ultrasound, plaque protrusion was observed in eight (8.8%) stented patients. Among them, six (6.6%) were free from angiographic signs of protrusion and only two (2.2%) had apparent angiographic signs of protrusion. During the early postoperative period, transient ischaemic attack was identified in four (4.4%) cases. One (1.1%) patient was found to develop ST-segment elevation acute myocardial infarction 24 hours after internal carotid artery stenting, followed by large hemispheric stroke on the side of stenting revealed on postoperative day 3. Nine (10%) patients according to the findings of intravascular ultrasound were diagnosed as having incomplete stent apposition after postdilatation, with the absence of such signs on angiography. Intravascular ultrasound during carotid stenting provides a more accurate assessment of such an event as atherosclerotic plaque protrusion through a stent's cells. At the same time, IVUS-guided assessment of the intraoperative outcome may prevent the risk for the development of stroke in the early postoperative period. Besides, intravascular ultrasound allows a more detailed assessment of stent apposition and the degree of stent expansion in order to optimize and improve the remote results of the operation.

Intraprocedural Stent Thrombosis: Case Series of a Rare Complication Managed Successfully

Intra-procedural stent thrombosis (IPST) is defined as the development of occlusive or non-occlusive new thrombus in or adjacent to a recently implanted stent before the PCI procedure is completed. The frequency of occurrence currently ranges between 0.5 – 1.7% of all PCI procedures and it seems to be considerably reduced with newer drug eluting stents and improved techniques. The occurrence of IPST is relatively rare, even in ACS patients, and is related strongly to clinical presentation and procedural factors (e.g., anticoagulation regimen, lesion type, presence of thrombus at baseline, stent under expansion and edge dissection etc.) than to baseline demographic characteristics. Imaging modalities like IVUS or OCT can prevent as well as identify the underlying cause for IPST. IPST not only decreases success rate of PCI but is also associated with higher rates of slow flow or no reflow, distal embolization and side branch closure. It is also associated with higher mortality, myocardial infarction, ischemia driven revascularisation and stent thrombosis on follow up. IPST can be managed immediately in cath lab and involves use of GP2b3a inhibitors, optimising stent apposition by repeat balloon dilatation, use of imaging to identify the cause and accordingly corrective measures to be taken. Rarely emergency CABG may be required if underlying cause cannot be corrected. Prevention is the key. IPST can be prevented by using newer anti-platelets, use of GP2b3a inhibitors especially in presence of ACS or high thrombus load, preparing the lesion well before stenting, use of atherectomy devices when needed, appropriate stent size selection and use of imaging modalities in complex lesions to optimise stent selection and apposition. We describe three cases of the intra procedural stent thrombosis under different clinical scenarios and its management.

Coronary restenosis

Coronary restenosis is the answer of the arterial wall to amechanical violation through balloon angioplasty, bare-metal (BM) stent implantation or rotational atherectomy through repeated narrowing. It has great clinical and prognostic relevance and occurs in approximately 30% of non-coated stents and in 10% of coated coronary stents. The wound healing process that precedes restenosis includes inflammatory reactions, cellular proliferation and remodeling of the arterial wall, where protein synthesis of the extracellular matrix is initiated. The inflammatory reaction activates platelets, leucocytes and monocytes and stimulates smooth muscle cells. The medications on the drug-eluting stents (rapamycin, paclitaxel, sirolimus, evarolimus and zotarolimus) inhibit cell division, are cytotoxic and only these sustainably influence restenosis. Whether they play arole in neoatherosclerosis needs to be determined. The mechanism of restenosis with implantation of drug-eluting stents is heterogeneous and associated with the deposition of T‑lymphocytes and fibrin. Risk factors for the development of restenosis include mechanical factors, such as incorrect apposition and expansion of stents, inflammation, diabetes mellitus, genetic factors, bypass operations, stent length and stent diameter. The restenosis rate is lower with drug-eluting stents and must be considered differently between the drug-eluting stents. Drug-eluting stents of the latest generation and drug-coated balloons (DCB) showed the best clinical and angiographic results for in-stent restenosis in randomized trials. The BM and older first-generation drug-eluting stents should be avoided. Further randomized studies are needed.

Protocol Adaptation of Optical Coherence Tomography in Lower Limb Arteries Revascularization

In lower limb arteries, assessment of stent apposition and/or the single opening of the diseased artery remains poor since this relies on 2-dimensional angiogram. Extrapolating experience gained with coronary arteries, optical coherence tomography (OCT) could provide 3-dimensional reconstructions of the arterial wall and the stent implanted. A modified protocol of OCT acquisition, which usually includes large amount of iodine contrast flush, is presented here in 3 patients with long and complex occlusion of the superficial femoral artery. Its potential benefits and wider application to improve patient outcomes are discussed.

Rotational atherectomy in everyday clinical practice. Association of Cardiovascular Interventions of the Polish Society of Cardiology (Asocjacja Interwencji Sercowo-Naczyniowych Polskiego Towarzystwa Kardiologicznego - AISN PTK): Expert opinion.

The common use of stents, including antiproliferative drug-eluting stents, has been a major breakthrough in invasive cardiology. Nowadays, a change in the clinical presentation of patients treated with percutaneous coronary intervention (PCI) is observed. The typical clinical characteristics now include advanced age, diabetes, chronic kidney disease, heart failure, and multilevel atherosclerosis. Age, diabetes, and chronic kidney disease are the main predictors of coronary artery calcifications. Severe coronary artery calcifications are the main factor limiting the efficacy of PCI. Successful stent implantation is challenging in the presence of calcifications, because it is difficult to achieve full stent expansion and proper stent apposition. Therefore, it is necessary to adequately prepare the lesion before stent implantation. This document presents the technique of rotational atherectomy (rotablation) as well as indications for and contraindications to the procedure, along with its possible complications and their prevention. Training in rotablation for operators as well as reimbursement policy for the procedure in Poland are also discussed.

GW29-e1386 Long term clinical effects of stent postdilatation versus non-postdilatation with current drug-eluting stents or bare metal stents - A Systemic review and Meta Analysis

Stent postdilatation following coronary stent implantation is often used to achieve optimal stent expansion and apposition in the current practice of percutaneous coronary intervention (PCI). Therefore our study aim to analysize the long term clinical benefit between the angiographic-guided

Refractory Vascular Wall Healing after Paclitaxel-Coated Nitinol Stent Implantation in the Femoropopliteal Artery: A High-Resolution Angioscopic Assessment.

It is unclear whether arterial healing occurs beyond 1 year following paclitaxel-coated stent implantation in peripheral artery disease. An 81-year-old woman with superficial femoral artery disease underwent endovascular therapy with a paclitaxel-coated stent. An angiography 21 months later revealed peri-stent contrast staining in the superficial femoral artery, and optical frequency domain imaging demonstrated incomplete stent apposition with significant positive vascular remodeling. High-resolution angioscopy detected positive vascular wall remodeling and in-stent yellow plaque more clearly than conventional angioscopy. Refractory superficial femoral arterial wall healing was apparent more than 20 months after paclitaxel-coated stent implantation.

Optical coherence tomography-verified longer balloon inflation time may provide better stent apposition and optimal index parameters.

Incomplete stent expansion and inadequate apposition predispose to stent thrombosis following percutaneous coronary intervention. Recent studies have shown that increasing the duration of balloon inflation during stent employment was beneficial. Thus, the balloon inflation time required for optimal stent expansion and apposition in patients receiving second-generation drug-eluting stents (DES) were determined using optical coherence tomography (OCT). Between April 2014 and March 2015, 38patients (28men, 10women; mean age 60.5 ± 11.4years) with stable angina pectoris due to single significant de novo coronary artery stenosis were prospectively enrolled. All patients were administered aspirin and clopidogrel and received weight-adjusted intravenous unfractionated heparin. Images of basal lesions were obtained using the C7XR LightLab Dragonfly OCT catheter. Expansion and apposition parameters improved with increasing duration of balloon inflation (30 s or 60 s) with nominal pressure (12 atm). Mean lesion length was 19.8 ± 7.6 mm. Mean stent diameter and length were 2.8 ± 0.36 mm and 24.9 ± 7.6 mm, respectively. With deployment of astent at nominal pressure with conventional duration, inadequate stent expansion and malapposition frequently occurred as detected by OCT; however, aballoon inflation duration of 60 s markedly improved stent expansion and apposition parameters without significant complications.

TCT-313 In-Vivo Acute Expansion of Bioresorbable Scaffolds and Metallic Stents in Normal Porcine Coronary Arteries: A Critical Appraisal of Compliance Chart Accuracy

Accurate sizing and stent apposition are of paramount importance to achieve an optimal stenting result. Bioresorbable scaffolds (BRS), in particular, require more rigorous implant optimization than drug eluting stent (DES) and bare metal stents (BMS) to achieve a favorable outcome. We investigated

TCT-506 Cut-off value of malapposition volume on resolution of acute incomplete stent apposition at one month using serial optical coherence tomography after cobalt- chromium everolimus-eluting stent implantation in patients with stable coronary artery disease.

A previous optical coherence tomography (OCT) study showed that incomplete stent apposition (ISA) of drug eluting stents is a major risk factor for stent thrombosis. The cobalt-chromium everolimus-eluting stent (CoCr- EES) incorporating a highly biocompatible stent is used in combination with short

TCT-470 Worldwide Everyday Practice Registry Assessing the Xposition S Self-apposing Stent in Challenging Lesions with Vessel Diameter Variance (SIZING Registry)

While performing a PCI, difficulties are encountered in vessels with very large diameter, significant diameter variance or difficult diameter estimation (e.g. STEMI). Optimization steps are required, which may be aggressive for the vessel or stent structure, without ensuring stent apposition. Self-

TCT-507 Increase of coronary lumen area with improved stent apposition after self-expandable stenting in total occlusions: results of the SPACIOUS pilot study

After successful percutaneous coronary intervention (PCI) of a chronic total occlusion (CTO), distal vessel diameter can increase 12-18% over time, due to recuperation of endothelial and smooth muscle cell function. Increase of diameter might lead to a mismatch of stent size and malapposition.

TCT-504 Incidence and natural course of incomplete stent apposition in heavily calcified lesions requiring rotational atherectomy prior to stenting: an optical coherence tomography study

Persistent or late acquired incomplete stent apposition (ISA) may be associated with late or very late stent thrombosis following drug-eluting stent implantation. Presence of calcium at the target lesion may increase the risk of ISA even after rotational atherectomy (RA) followed by stenting with

TCT-503 Cut-off value of strut vessel distance on resolution of acute incomplete stent apposition at one month using serial optical coherence tomography after cobalt- chromium everolimus-eluting stent implantation in patients with stable coronary artery disease

TCT-503 Cut-off value of strut vessel distance on resolution of acute incomplete stent apposition at one month using serial optical coherence tomography after cobalt- chromium everolimus-eluting stent implantation in patients with stable coronary artery disease