Longitudinal Stent Research Articles

Longitudinal Stent Deformation at the Proximal Segment of the Left Main Coronary Artery Caused by a Stuck OCT Catheter: Case Report and Review of Literature.

It has been rarely reported that a stuck optical coherence tomography (OCT) catheter can lead to longitudinal stent deformation (LSD). This complication can result in incomplete stent apposition and dissection after stent implantation. In this study, we present a case where a bailout stent was implanted in the distal segment of the left anterior descending artery (LAD) after longitudinal stent deformation caused by a stuck OCT catheter. This approach was taken to prevent acute stent thrombosis, subacute stent thrombosis, in-stent restenosis (ISR), and death. The patients were followed up for one year, and no adverse events were observed.

Longitudinal Stent Elongation: A Rare Complication of Third-Generation Drug-eluting Stent Platform

Abstract Longitudinal stent deformation (LSD) is an infrequent complication of percutaneous coronary intervention. While the occurrence of gross LSD is a rare phenomenon, minor changes in length are common and have been recognized as accepted behavior of stents during implantation. Due to the proximity of the guide catheter, ostial or ostio-proximal lesions are prone to stent deformation either by the guide or other devices during navigation. Moreover, to satisfy the fractal geometry of coronary bifurcation, the proximal optimization technique is commonly performed during different bifurcation procedures, which can subject the stent to extreme overexpansion resulting in structural deformation. We describe two cases of longitudinal stent elongation during ostial deployment and try to analyze the factors behind this rare, yet complicated behavior of the latest-generation drug-eluting stent.

Longitudinal stent elongation or shortening after deployment in the coronary arteries: which is dominant?

BackgroundStent manufacturers always record stent shortening data while they do not record stent elongation data. The aim of this study is to identify both stent shortening and elongation occurring after deployment in the coronary arteries and know their percentage.ResultsThe length of coronary stents was measured by intravascular ultrasound (IVUS) by (1) edge-to-edge (E-E) length, measured from the appearance of the first distal strut to the last proximal strut, and (2) area-to-area (A-A) length, measured from the first distal struts seen at more than one IVUS quadrant to the last proximal struts seen at more than one IVUS quadrant. Stent shortening was defined as both E-E and A-A lengths were shorter than the manufacturer box-stated length (shortened group). Stent elongation was defined as both E-E and A-A lengths were longer than the manufacturer box-stated length (elongated group), otherwise unchanged group. Consecutive 102 stents deployed in ischemic patients were included. Stent elongation was detected in 67.6% (69 stents), and shortening was detected in 15.7% (16 stents), while unchanged stents were detected in 16.7% (17 stents). Although the 3 groups had similar box-stated length and predicted foreshortened length, they had significantly different measurements by IVUS, p<0.001 for each comparison. Differences from box-stated length were 1.9±1.4mm, −1.4±0.4mm, and 0.4±0.3mm, respectively, p<0.001. The elongated group had significantly longer differences from the corresponding box-stated and predicted foreshortened lengths, while the shortened group had significantly shorter differences from the corresponding box-stated length and similar foreshortened length. By multinomial regression analysis, the plaque-media area and stent deployment pressure were the independent predictors of the stent length groups, p=0.015 and p=0.026, respectively.ConclusionsChange in stent length is not only shortening—as mentioned in the manufacturer documents—but also stent elongation. Stent elongation is dominant, and the most important predictors of longitudinal stent changes are plaque-media area and stent deployment pressure.

Pericardial Tamponade Caused by Rotational Atherectomy Ablation Grinding Through a Barrier Stent Protruding From the Diagonal Artery: A Case Report

Rotational atherectomy (RA) has been described in case reports to be effective in ablating under-expanded stents. We present a case of calcified bifurcation lesion percutaneous coronary intervention (PCI), in which the branch stent protruding into main branch blocked the balloon getting through, and the following RA led to pericardial tamponade. The first stent was deployed from the proximal of left anterior descending artery (LAD) to the proximal of diagonal for an 80-year-old man who suffered from non-ST-elevation myocardial infarction to make a Culotte dual stent PCI. The operator failed to make balloon get through the struts protruding into LAD lumen anyway. After RA drill through the LAD lumen, it showed an excellent angiographic outcome. Stent deployment in LAD was successful, but pericardial tamponade occurred in a short time. After pericardiocentesis was performed under fluoroscopic guidance, the patient was uneventful. After 1 year, the follow-up coronary computed tomography (CT) angiography showed no in-stent restenosis, stent fracture or disrupted struts protruding outside of the vessel’s outline of LAD and the first diagonal (D1). This case shows stents’ RA could be dangerous in grinding across the stents’ lateral hole in an unsymmetrical lumen. Although RA could be a useful remedy in the situation of under-expansion of implanted stents, the debulking should be performed for longitudinal stent ablation and cautiously performed for bifurcation lesion in which the protruding stents from side branch were unsymmetrically blocking the path. J Med Cases. 2021;12(6):230-232 doi: https://doi.org/10.14740/jmc3678

Impact of Coronary Artery Curvature on the Longitudinal Stent Foreshortening: Real-World Observations

Longitudinal stent foreshortening is a known phenomenon, however, the impact of coronary artery curvature on longitudinal stent foreshortening remains unclear. The aim of this study is to determine the impact of coronary artery curvature on the longitudinal stent foreshortening in the real-world scenarios. A total of 86 consecutive patients underwent coronary stent implantation were included in the present study. The degree of coronary artery curvature was defined as the length of the coronary artery curvature divided by the straight length. Longitudinal stent foreshortening was defined as the stent length after implantation divided by the stent length before implantation. The mean longitudinal foreshortening rate of coronary stents was about 94% in curved coronary arteries. Longitudinal stent foreshortening rate was positively correlated with the degree of coronary artery curvature (r = –0.86, P < 0.01). Coronary artery curvature is associated with significant longitudinal foreshortening of coronary stents, thus longitudinal foreshortening should be considered on deciding the stent length in curved coronary artery and a longer stent is usually needed in curved coronary artery.

Effectiveness of the proximal optimization technique for longitudinal stent elongation caused by post-balloon dilatation.

To evaluate the effectiveness of the proximal optimization technique (POT) to prevent longitudinal stent elongation. The mechanism of stent elongation, which occurs after post-balloon dilation, is still unclear. A total of 103 lesions treated with optical coherence tomography guided coronary intervention between May 2013 and November 2017 were retrospectively analyzed. Lesions were divided according to the circumferential degree of malapposition at the stent edge immediately after deployment into well-apposed group (<180°) and malapposed group (≥180°). Post-dilation was performed from distal to proximal within the stent until August 2016 (non-POT cohort), and POT was applied thereafter (POT cohort). In the POT cohort, post-dilation was done at the proximal portion of the stent with sufficiently large balloon to minimize malapposition followed by distal dilatations. Stent elongation length was defined as the change in stent length from stent deployment to after post-dilatation. In the non-POT cohort, 72 lesions, including 54 lesions in the well-apposed group and 18 in the malapposed group were analyzed. Stent elongation length was significantly longer in the malapposed group than in the well-apposed group (1.51 ± 1.34 mm vs 0.13 ± 0.84 mm, P < 0.01). In the POT cohort, 31 lesions including 21 in the well-apposed group and 10 in the malapposed group were analyzed. Stent elongation length was not significantly different between the groups (-0.09 ± 0.91 mm vs 0.30 ± 0.99 mm, P = 0.29). Malapposition of the stent edge is responsible for longitudinal stent elongation caused by post-dilatation. POT appeared to effectively prevent longitudinal stent elongation.

Impact of post-dilatation on longitudinal stent elongation: An in vitro study

ObjectivesTo evaluate whether balloon inflation for post-dilatation causes longitudinal stent deformation (LSD). Methods and resultsTwo stents, sized 2.5mm×28mm and 3.5mm×28mm (Nobori®, biodegradable polymer biolimus-eluting stent; Ultimaster®, biodegradable polymer sirolimus-eluting stent; Terumo Co., Tokyo, Japan), were deployed at nominal pressure in straight and tapered silicon vessel models. Then, post-dilatation was performed in two ways: dilatation from the distal (D-P group) or proximal (P-D group) side of the stent. Microscopic findings showed that the stents were elongated during every step of the procedure regardless of the post-dilatation method and type of vessel model. The D-P group showed linear elongation during each step of post-dilatation (straight model: 28.7±0.3mm vs. 29.9±0.3mm, p=0.002; tapered model: 28.0±0.1mm vs. 29.9±0.1mm, p<0.001). In contrast, in the P-D group, the most significant change was observed in the first step of post-dilatation and only slight changes were observed thereafter (straight model: 28.6±0.1mm vs. 29.5±0.1mm, p<0.001; tapered model: 28.2±0.1mm vs. 29.5±0.1mm, p<0.001). Optical frequency domain imaging analysis showed that the frequency of stent strut malapposition was positively correlated with the percentage change in stent length (r=0.74, p<0.0001). ConclusionLSD was observed during every step of post-dilatation in both the straight and tapered vessel models. However, some differences were observed between the D-P and P-D groups. Minimizing stent strut malapposition may reduce the risk of LSD.

Effects of Metal Material Stent Design Parameters on Longitudinal Stent Strength

The longitudinal stent deformation (LSD) was usually caused by the external force in the blood vessel. The effects of metal material stent design parameters on the longitudinal stent strength (LSS) were studied using finite element method (FEA). A longitudinal stent compression model was developed and a rigid surface was used to compress the stent after stent deployment in coronary arteries. Results showed that the connector length, the strut amplitude and the curvature radius at the crown junctions influenced the LSS hardly. However, the number of connector played the most significant role in the LSS, and increasing the number of connectors can substantially improve the LSS, and the LSS of stent with four connectors was nearly three times than that of the stent with two connectors. For the shape of connector, the LSS of the S-stent, M-stent and L-stent were successively increased. With regard to the L-stent, increasing the width of connector can improve the LSS. Reasonably changing stent design parameters can effectively strengthen the LSS. Conclusions obtained from this paper can help surgeons to select appropriate stents and designers to optimize the stent design to reduce the LSD.

Haemodynamic Variations of Flow to Renal Arteries in Custom-Made and Pivot Branch Fenestrated Endografting

This study aimed to investigate variation of blood flow to renal arteries in custom-made and pivot branch (p-branch) fenestrated endografting, using a computational fluid dynamics (CFD) technique. Idealised models of custom-made and p-branch fenestrated grafting were constructed on a basis of a 26mm stent graft. The custom-made fenestration was designed with a 6mm diameter, while the 5mm depth renal p-branch was created with a 6mm inner and 15mm outer fenestration. Two configurations (option A and option B) were constructed with different locations of p-branches. Option A had both renal p-branches at the same level, whereas option B contained two staggered p-branches at lower positions. The longitudinal stent orientation in both custom-made and p-branch models was represented by a takeoff angle (ToA) between the renal stent and distal stent graft centreline, varying from 55° to 125°. Computational simulations were performed with realistic boundary conditions governing the blood flow. In both custom-made and p-branch fenestrated models, the flow rate and wall shear stress (WSS) were generally higher and recirculation zones were smaller when the renal stent faced caudally. In custom-made models, the highest flow rate (0.390L/min) was detected at 70° ToA and maximum WSS on vessel segment (16.8Pa) was attained at 55° ToA. In p-branch models, option A and option B displayed no haemodynamic differences when having the same ToA. The highest flow rate (0.378L/min) and maximum WSS on vessel segment (16.7Pa) were both calculated at 55° ToA. The largest and smallest recirculation zones occurred at 90° and 55° ToA respectively in both custom-made and p-branch models. Custom-made fenestrated models exhibited consistently higher flow rateand shear stress and smaller recirculation zones in renal arteries than p-branch models at the same ToA. Navigating the renal stents towards caudal orientation can achieve better haemodynamic outcomes in both fenestrated devices. Custom-made fenestrated stent grafts are the preferred choice for elective patients. Further clinical evidence is required to validate the computational simulations.

Impact of stent platform on longitudinal stent deformation: an in vivo frequency domain optical coherence tomography study.

Recently, longitudinal coronary stent deformation has been highlighted as a possible cause of drug-eluting stent failure. Although bench tests and in vivo studies have demonstrated difference in longitudinal stent strength among the stents with different platforms, its clinical impact is still unknown. Furthermore, it is unknown if modified stent platform favorably affect the incidence of stent deformation. The aim of this study was to investigate the longitudinal deformation of the everolimus-eluting stents (EES) with different stent platforms by using frequency domain optical coherence tomography (FD-OCT). Seventy-eight lesions treated with EES (Xience Prime: n=26, Promus element: n=29, Promus premier: n=23) were studied. After successful stent implantation, FD-OCT was performed and stent length was measured using three-dimensional reconstruction of the images in vivo. Percent longitudinal stent shortening (%SS) was defined as the in vivo stent length divided by nominal stent length. Longitudinal stent deformation was defined as %SS>10%. Patients' and procedural characteristics were similar among 3 EESs. There was no difference in mean %SS between Xience Prime, Promus Element and Promus Premier (1.0±5.8, 2.9±6.7 and 0.8±3.7%, p=0.322). Incidence of the longitudinal stent deformation was significantly higher in Promus Element than the other stents (0, 13.8 and 0%, p=0.028). Incidence of longitudinal stent deformation was different between EESs with different stent platforms. Stent material, stent design and/or stent delivery balloon may affect longitudinal stent deformation.

Longitudinal stent foreshortening of Stentys Xposition S self-apposing stents and its impact on overlapping stenting strategy

Longitudinal stent foreshortening of Stentys Xposition S self-apposing stents and its impact on overlapping stenting strategy

TCTAP A-142 Longitudinal Stent Elongation: Is Stent Elongation Occurs in Our Daily Practice?

We experienced two cases of longitudinal stent elongation (LSE) during stent deployment and disclose that LSE occurs when stents were expanded in air pressure and in malapposition vessel models. Following tests were performed to disclose the occurrence LSE. Test1: Five kinds of drug eluting stents

INCIDENCE AND CLINICAL IMPACT OF LONGITUDINAL STENT DEFORMATION AFTER THE PROMUS ELEMENT PLATINUM CHROMIUM-EVEROLIMUS ELUTING STENT IMPLANTATION

The PROMUS Element platinum-chromium everolimus-eluting stent (PtCr-EES) has a novel metal and stent design intended to improve deliverability, comformability, and radial strength, whereas such features might have the trade-off of reducing longitudinal stent strength, which would account for the

Abstract 13701: Impact of Stent Platform on Longitudinal Stent Deformation: an in vivo 3-dimensional Optical Coherence Tomography Study

Introduction: Recently, longitudinal coronary stent deformation has been highlighted as a possible cause of drug-eluting stent failure. Although bench tests and in-vivo studies have demonstrated difference in longitudinal stent strength among the stents with different platforms, its clinical impact is still unknown. The aim of this study was to investigate the longitudinal deformation of the everolimus-eluting stents (EES) with different stent platforms by using 3-dimensional frequency domain optical coherence tomography (3D FD-OCT). Methods: Fifty-nine lesions treated with EES (Xience Prime (CoCr-EES): n=28, Promus element (PtCr-EES): n=31) were studied. Stent length was measured by 3D FD-OCT. Percent longitudinal stent shortening (%SS) was defined as the longitudinally shortened stent length standardized by nominal stent length. Longitudinal stent deformation was defined as %SS &gt;10%. Results: Patients’ and procedural characteristics were similar between CoCr- and PtCr-EES. There was no difference in mean %SS between PtCr-EES and CoCr-EES (3.1±6.5 vs. 0.9±5.6%, p=0.197). However, incidence of longitudinal stent deformation was significantly higher in PtCr-EES than in CoCr-EES (16.1% vs 0%, p=0.026) (Figure). Conclusions: Incidence of longitudinal stent deformation was different between EESs with different stent platforms. Stent material, stent design and/or stent delivery balloon may affect longitudinal stent deformation.

Compression longitudinale de stent dans le traitement d’une bifurcation coronaire

Longitudinal stent deformation is defined as a compression of stent length after its implantation. It's a rare complication but dangerous seen with several stents. We reported a case of longitudinal stent deformation during bifurcation lesion treatment with a Promus Element® and we perform a short review of this complication.

The Relationship Between Post-Stent Strut Apposition and Follow-Up Strut Coverage Assessed by a Contour Plot Optical Coherence Tomography Analysis

This study sought to evaluate the relationship between post-stent strut apposition and follow-up strut coverage using contour plot optical coherence tomographic analysis. Tracking the fate of interested regions of struts at different time points has not been investigated. Post-intervention and 6-month follow-up optical coherence tomographic evaluations were performed in 82 patients treated with biolimus- (n = 37) or sirolimus-eluting stents (n = 45). Post-stent apposition was classified as embedded, apposed, or malapposed. For volumetric stent evaluation, the post-intervention strut-artery distance and the neointimal thickness at follow-up were measured as a function of the circumferential arc length and longitudinal stent length. Computer-generated contour plots of the strut-artery distance and neointimal thickness were compared. The percentages of embedded and malapposed struts after intervention were 1.8% (Interquartile range [IQR]: 0.6% to 6.2%) and 2.3% (IQR: 0.5% to 5.2%), respectively. The percentages of uncovered and malapposed struts at 6 months were 16.0% (IQR: 7.4% to 33.3%) and 0% (IQR: 0% to 0.7%), respectively. The percentage of uncovered struts at 6 months varied significantly with post-stent strut apposition (0% [IQR: 0% to 11.4%] in embedded, 16.3% [IQR: 8.1% to 31.3%] in apposed, and 26.8% [IQR: 0% to 56.3%] in malapposed, p < 0.001 for all pairwise comparisons). In lesions without tissue prolapse, embedded struts were all covered (100% covered struts) compared with those with tissue prolapse (76.8% covered, p < 0.001). The optical coherence tomography-guided optimization of stent strut apposition enhances strut coverage at follow-up. This comprehensive method for evaluating strut apposition may provide more useful information to understanding the serial changes in strut coverage. (Neointimal Coverage After Implantation of Biolimus Eluting Stent With Biodegradable Polymer: Optical Coherence Tomographic Assessment According to the Treatment of Dyslipidemia and Hypertension and the Types of Implanted Drug-Eluting Stents; NCT01502904).

Effects of stent design on new clinical issue of longitudinal stent compression in interventional cardiology

In recent years, interventional cardiologists have discussed over a new clinical issue called longitudinal stent compression (LSC), a failure mode not previously observed in coronary stents. This phenomenon occurs when the physician attempts to cross a deployed stent with a second device, causing the stent to dramatically shorten when two devices are accidentally entangled. While this phenomenon has been observed with a number of stent platforms, it seems more common with the Element stent. In this paper, a computational LSC model using finite element analysis was developed. A systematic investigation was conducted in attempts to quantify individual contribution of the stent design pattern, connector number, design parameter, and connector location on LSC. Computational simulations were performed on two representative coronary stents resembling Element and Endeavor for comparison. Simulation results show that the connector number plays the most significant role in LSC. The LSC could be easily tripled or quadrupled for the same stent design simply by increasing the connector number from two to three. The design pattern and design parameter play a secondary role in LSC, with the LSC improved by up to 30 and 65%, respectively. It was also found that the LSC could be doubled for the Element stent simply by rearranging its connector location. This small design tweak could help improve the current Element LSC significantly, while still maintaining the majority of its excellent deliverability. These findings could provide great insights into this new clinical issue and help optimize future stent design to reduce the associated risk involved in LSC.

Prevalence and anatomical features of acute longitudinal stent deformation: An intravascular ultrasound study

We report the prevalence and anatomical features of longitudinal stent deformation as detected by intravascular ultrasound (IVUS) BACKGROUND: Angiographic studies have recently reported longitudinal stent deformation as a mechanical complication occurring during percutaneous coronary intervention; however, there are no IVUS studies on this phenomenon We retrospectively analyzed 1,489 consecutive stent-treated lesions in 1,057 patients who underwent IVUS post-stent implantation Seventeen longitudinal stent deformations in 17 lesions (1.1% per lesion) in 17 patients (1.6% per patient) were identified by IVUS. Of the 17 IVUS-detected deformations, only three deformations (17.6%) were detectable by angiography. By IVUS, there were three patterns of longitudinal stent deformation: (1) Deformation with intra-stent wrinkling and overlapping of the proximal and distal stent fragments within a single stent (n = 14), (2) deformation with elongation (n = 2), and (3) deformation with shortening (n = 1). Most of the deformations were located near to the proximal stent edge (88%), consistent with the finding that they were observed in 11 ostial (65%) and eight left main lesions (47%), and 8.3% of 96 left main stented lesions had evidence of deformation By IVUS, longitudinal stent deformation during percutaneous coronary intervention was seen more frequently than in previous studies; however, it is still uncommon (1.1%) except in the left main location. The most frequent pattern was intrastent wrinkling and overlapping of the proximal and distal stent fragments.

Occurrence of longitudinal stent compression before stent deployment: Two case studies

Several recent reports have described the occurrence of longitudinal stent deformation (LSD, defined as the distortion or shortening of a stent along the longitudinal axis), following its successful deployment. However, few reports have described LSD prior to any stent deployment. This previously unrecognized complication is the result of modifications to stent design. It has been noted that the new-generation stent platforms have a reduced number of connectors, which in turn causes a reduction in longitudinal stent strength. To corroborate previous findings by our lab and others (Vijayvergiya et al, 2013), we describe here two cases of LSD prior to stent deployment that occurred due to crushing of the proximal stent edge by the guide catheter while attempting to withdraw the crimped stent. In addition, we discuss the associated risk factors, such as the length of the stent, and specific management strategies, including technical guidelines and use of fluoroscopic guidance for maneuvering the stent during the procedure.

New clinical failure mode triggered by a new coronary stent design

Longitudinal stent compression (LSC) is a new failure mode not previously observed in coronary stents. This phenomenon occurs when the physician tries to cross the deployed stent with other devices. While this phenomenon has been observed with a number of stent designs, it seems more common with the Element stent. A computational LSC model using finite element analysis was developed. Computational simulations were performed on two representative coronary stents in the current market resembling Element and Endeavor in attempts to quantify individual contribution of the stent design pattern and connector number on LSC. Simulation results show that the connector number plays the most significant role in the development of the LSC issue. The LSC could be easily tripled for the Element stent simply by increasing the connector number from two to three. The stent design pattern plays a secondary role in LSC. The LSC could be improved by up to 30% when the design pattern changes from the offset peak-to-peak design (Element) to the peak-to-peak design (Endeavor). Conclusions obtained from this paper may help clinical stent selection and future stent design optimization to reduce the risk associated with longitudinal stent compression.