光学相干断层成像评价药物洗脱支架置入术后晚期支架贴壁不良

目的 探讨药物洗脱支架(DES)置入术后晚期支架贴壁不良的特点.方法 分析32例(包括51支血管、共置入71个支架)置入DES 1年后[(14.8±5.2)个月]行光学相干断层成像(OCT)检查的患者资料,对支架节段的OCT图像每间隔0.5 mm取1帧图像进行分析,找出贴壁不良的支架金属结构,测量支架到参照血管内壁的距离及支架表面内膜厚度,分析晚期支架贴壁不良的特点.结果 OCT检查在7例(21.9%)患者中检出支架贴壁不良,其中4例合并支架段血管的正性重构,1例重叠置入支架,2例发现由血栓覆盖支架金属结构,7例患者随访期间无心脏不良事件发生.97.6%的支架金属结构完全贴壁并不同程度的内膜覆盖,2.4%的支架金属结构贴壁不良,包括1.2%的支架金属结构位于血管分支开口.位于血管分支开口的支架金属结构与其他贴壁不良支架表面的内膜覆盖厚度差异无统计学意义[(0.06±0.05)mm比(0.05±0.03)mm,P>0.05].绪论晚期支架贴壁不良见于DES置入最初的贴壁不良、血管壁正性重构、重叠置入支架以及支架金属结构位于分支血管开口;贴壁不良的支架金属结构表面亦有不同程度的内膜覆盖.     

Evaluating Stent Optimisation Technique (StentBoost®) in a Dedicated Bifurcation Stent (the Tryton™)

Background/PurposeTo evaluate the use of StentBoost® in the Tryton™ dedicated SideBranch Stent.Methods & ResultsThe Tryton™ SideBranch Stent has been effectively used to manage complex bifurcations. However, the paucity of scaffolding in the proximal part of the stent makes it often difficult to visualise under standard radiographic imaging. We set out to evaluate whether by using an augmented radiographic imaging technique it was possible to aid visualisation of the stent. In particular the so call 'wedding ring' band which is crucial to the procedural success. We further evaluated whether it was possible to determine the apposition of the stent at the carina, its coverage and the ability to aid recrossing of the struts closest to the carina as well as the added radiation exposure.ConclusionsStentBoost® was found to be invaluable to the procedural success of the Tryton™ deployment without adding any extra cost to the procedure and with only a 3.7% increase in radiation to the patient. It allowed enhanced visualisation in all cases to aid apposition, recrossing and coverage.     

Relative dependence of diameters of branches in coronary bifurcations after stent implantation in main vessel--importance of carina position

BACKGROUND AND AIM: Bifurcation lesions are relatively frequently encountered in everyday interventional practice. Stenting of the vessel chosen to be main (usually the larger one) frequently leads to stenosis at the ostium of the side branch (SB) and compromises its flow (side branch compromise--SBC). The relative dependence of main and side branch diameters, based on the concept of carina displacement of stent struts, was examined in a cohort of patients with bifurcation stenting. METHODS: We accept that the basic mechanism for SBC after stent placement in the parent vessel is carina shifting from expanded stent struts. The ostial SB minimal lumen diameter (MLD), percentage diameter stenosis (%DS) at maximal and calculated actual carina displacement, as well as distal limb diameter (DLD) in the main branch were calculated and compared with actually observed values. RESULTS: A group of 55 consecutive patients with acceptable quality angiograms formed the study population. General patient characteristics were similar to other bifurcation studies. Left anterior descending artery was predominantly treated in 73% of patients. There was worsening SB ostial stenosis after stent implantation (%DS increase from 48%+/-23% to 69%+/-21%, p <0.001) and final improvement because of kissing balloon inflation or SB postdilatation (post vs. final-69+/-21% and 53+/-25%, p<0.001). Stent implantation causes straightening of the main vessel, evident from a significant increase in angle C (pre- 148 degrees +/-19 degrees vs. 156 degrees +/-16 degrees after stenting, p=0.007). Relations between observed and predicted values for main branch DLD and %DS demonstrated a good correlation between predicted and observed values (for DLD r=0.66, p<0.001, and for %DS r=0.53, p <0.001). There was an excellent fit of regression lines between theoretical predictions and actual measurements for side branches (MLD r=0.91, p<0.001, %DS r=0.89, p<0.001).CONCLUSIONS: Carina displacement from stent struts is a major mechanism governing changes in coronary bifurcations after main vessel stenting. Improvement in the ostium of the side branch causes shifting back of the carina and a decrease of main vessel diameter. The long-term consequences of this phenomenon are not currently known.     

Limited balloon expansion through the struts of the Palmaz-Schatz and NIR stents compared with the Multi-Link stent

After placing a stent in the main vessel of a bifurcation lesion, it is sometimes necessary to perform further balloon inflation in order to treat an ostial lesion in a side branch. The stent struts may prevent full balloon expansion at the ostium of a side branch, resulting in residual ostial stenosis. The degree of completeness of balloon inflation may vary significantly depending on the stent design and structure. A model of a bifurcation lesion with an angle of 45 degrees was created from acrylic resin. The diameters of the main vessel and the side branch were both 3.5 mm. Deployment of the Palmaz-Schatz stent (n=5), NIR stent (n=5) or Multi-Link stent (n=5) was performed in the main vessel with a 3.5-mm balloon catheter inflated to 12 atm. A 3.5-mm balloon catheter was then inflated to 12 atm through the stent struts of the main vessel and into the ostium of the side branch. The degree of completeness of balloon inflation (% balloon expansion) was calculated as (smallest diameter of balloon catheter/reference diameter of balloon catheter) x 100%. The minimal lumen diameter (MLD) and cross-sectional area (CSA) at the ostium of the side branch created with the stent struts were also measured. Limited balloon expansion through the struts was observed with the Palmaz-Schatz stent and the NIR stent, but almost full balloon expansion was observed with the Multi-Link stent (% balloon expansion: Palmaz-Schatz stent 80%, NIR stent 60%, Multi-Link stent 94%, p<0.01). The MLD and CSA of the dilated struts, representing the ostium of the side branch, of the Palmaz-Schatz stent (2.2+/-0.1 mm, 4.5+/-0.3 mm2) and the NIR stent (1.8+/-0.1 mm, 3.1+/-0.3 mm2) were significantly smaller compared with those of the Multi-Link stent (3.0+/-0.2 mm, 8.4+/-0.6 mm2) (p<0.01). The struts of the Palmaz-Schatz stent and the NIR stent deployed in the main vessel of a bifurcation prevent full expansion of a balloon catheter inflated at the side branch ostium. In contrast, almost full balloon expansion through the struts of the Multi-Link stent is achieved.     

Membranous diaphragm formation after simultaneous kissing stenting with sirolimus‐eluting stents for the left main bifurcation

Two patients who underwent simultaneous kissing stenting with sirolimus‐eluting stents in the left main coronary artery were investigated with optical coherence tomography (OCT) at just more than 1 year postoperatively. In both cases, follow‐up angiogram indicated complete coverage of the new metal carina with a membranous diaphragm, yet OCT showed varying tissue‐coverage patterns transitioning from stent inflow to stent outflow. These patterns included single‐strut coverage, bridge‐like membrane formation between more than 1 strut, and end‐to‐end coverage of the carina; no uncovered stent struts were detected. OCT also demonstrated mixed patterns of tissue characteristics on the metal carina, ranging from poor endothelialization to modest neointima formation. These varying tissue characteristics suggest that the process of tissue coverage in the metal carina is different from that occurring on the vessel wall; this may indicate delayed healing in the carina. © 2013 Wiley Periodicals, Inc.     

Evaluation of a Bifurcation Drug‐Eluting Stent System versus Provisional T‐Stenting in a Perfused Synthetic Coronary Artery Model

Background: Provisional T‐stenting is a widely used strategy for the treatment of coronary artery bifurcation lesions. However, the use of conventional stents in this setting is limited by multiple factors; this includes technical considerations such as wire wrap when accessing the involved vessel, and stent overlap at or near the carina of the lesion. In addition, current slotted tube stent technology tends to be associated with gaps in the coverage of the side branch ostium, which may result in restenosis in that segment of the lesion. The Pathfinder device, now more commonly referred to as the Xience Side Branch Access System (Xience SBA) is a drug‐eluting stent (DES) designed specifically to assist in the treatment of bifurcation lesions by allowing wire access into the side branch, irrespective of the treatment strategy to be employed. Methods: The Xience SBA drug‐eluting stent was compared with the standard Vision coronary stent system using a provisional T‐stenting strategy in a perfused synthetic model of the coronary vasculature with side branch angulations of 30°, 50°, 70°, and 90°. Stent delivery was performed under fluoroscopic guidance. Following the procedure, high‐resolution 2D Faxitron imaging was used to evaluate deployment accuracy of the side branch stent relative to the main branch stent. Results: Deployment of the Xience SBA was accomplished in the same total time as the standard stents in a provisional T‐stenting approach (14.9 vs. 14.6 minutes). However, the time required to achieve stent deployment in the main branch was less with the Xience SBA (4.0 vs. 6.6 minutes), and as a result, total contrast usage (49.4 vs. 69.4 cm³) and fluoroscopy time (5.1 vs. 6.2 minutes) was lower. Additionally, the Xience SBA had a lower incidence of wire wrap (22% vs. 89%) and less distal protrusion of the side branch stent into the main branch (0.54 vs. 1.21 mm). Significant gaps in ostial side branch coverage were not seen in either group. Conclusions: The Xience Side Branch Access DES is a viable device for consistently accessing coronary bifurcation lesions; it allows for easy wire access into the side branch. This may assist the operator in overcoming those well‐recognized limitations associated with use of standard one‐ or two‐stent strategies. In this perfused synthetic coronary model, Xience SBA deployment required less contrast usage and shorter fluoroscopy times. Further testing of this device is warranted.     

Immediate results of bifurcational stenting assessed with optical coherence tomography

Background : A tubular stent may adapt with difficulty to coronary bifurcation lesions (CBLs). Methods : Time domain or frequency domain (FD) optical coherence tomography (OCT) was performed to assess strut apposition immediately after stent implantation across four segments inside the bifurcation, in a consecutive series of patients. OCT pullbacks were performed in the main vessel (MV). Results : A total of 13,142 struts in 45 CBL in 41 patients were assessed. Strut malapposition was significantly more frequent in the half bifurcation facing the side‐branch (SB) ostium (42.9%) than in the proximal segment of the bifurcation 11.8%, half bifurcation opposite the SB 6.7%, or the distal segment 5.7% (all P < 0.0001). Lesions (n = 15) treated with stenting of both MV and SB had a total higher rate of malapposition than those (n = 30) treated with stenting of the MV only (17.6% vs. 9.5%; P = 0.0014). In latter group, lesions treated with FD‐OCT‐guided stent implantation (n = 13) presented a lower rate of malapposition than those treated with conventional angiographic‐guided stent implantation (n = 17) (7.1% vs. 17.5%; P = 0.005). Conclusions : In CBL, strut malapposition is particularly high at the SB ostium. However, a strategy of stenting MV only with adjunctive FD‐OCT guidance is associated with lower rates of malapposition. © 2012 Wiley Periodicals, Inc.     

A New Stent Design for the Treatment of True Bifurcation Lesions: H-Side Branch Stents

Background: There has been much debate for the adequate treatment strategies for true bifurcation lesions. The purpose of this study is to introduce and test a novel stent design for the treatment of true bifurcation lesions.
Methods: This side branch stent is composed of three parts: proximal, connecting, and distal parts. The distal part for the side branch vessel has a slope-side stent margin for circumferential coverage of the ostium and one radio-opaque marker for targeting the carina. The proximal part with two radio-opaque markers operates for safe stent delivery and useful guidance for a more precise placement of the distal part on the side branch ostium. Results of the in vitro test in the acrylic resin-made bifurcation phantom model were evaluated with microcomputer tomography. Animal experiments with this new stent platform were also performed in five pigs.
Results: In vitro test and microcomputer tomography showed complete coverage of the side branch ostium circumferentially with stent struts, and the absence of stent struts in the main vessel above the side branch ostium level. This side branch stents were successfully deployed in all 5 pigs. The results of animal experiments were also similar to those of in vitro tests.
Conclusions: In vivo and vitro tests demonstrated the effective modality of this side branch stent for the treatment of true bifurcation lesions. (J Interven Cardiol 2010;23:54–59)     

OCT对冠状动脉介入术后即刻支架周围组织结构改变的评价

目的通过光学相干断层成像(OCT)初步评价冠状动脉内支架术后即刻支架周围组织结构特点。方法随机入选15例冠状动脉粥样硬化性心脏病(冠心病)行支架置入术患者,在患者置入支架后用OCT成像系统评价术后即刻支架释放情况及支架贴壁情况。结果15例患者共置入36枚支架,OCT检查得到满意图像并显示有14例患者冠状动脉内支架各部分充分释放,支架与血管壁贴合良好,无斑块组织向血管腔内突入,支架连接处贴合好;有1例患者支架部分节段释放不充分,支架与血管壁贴合不良,支架连接处贴合欠佳。结论OCT检查可充分评价支架释放及血管壁贴合和支架连接处管壁贴合情况,是检查支架术后支架周围组织结构的一种重要方法。     

A modified balloon crush approach improves side branch access and side branch stent apposition during crush stenting of coronary bifurcation lesions.

OBJECTIVES: Despite the advent of drug eluting stents and newer interventional techniques designed to treat the main vessel and side branch in bifurcation stenoses, optimal treatment of the side branch remains problematic. We aimed to assess the feasibility of a modified balloon crush technique for percutaneous treatment of coronary bifurcation stenoses. BACKGROUND: Use of the crush technique in bifurcation stenoses remains limited by access to the side branch after main vessel stent deployment, as well as limitations of side branch stent deployment. The modified balloon crush technique aims to improve side branch access and stent apposition. METHODS: The modified balloon crush is similar to the previously described balloon crush technique. Following side branch stent deployment, a balloon positioned in the main vessel is deployed to crush the proximal side branch stent. A guide wire is then placed into the side branch with a subsequent high-pressure balloon inflation at the side branch ostium. This opens the stent struts at the ostium of the side branch, facilitating future passage of the guide wire following main vessel stent deployment, prior to kissing balloon inflation. RESULTS: We performed this modification of the crush technique safely in 10 patients. We were successful in obtaining side branch access in nine of ten patients following initial main vessel stent deployment. In the only failure, there was a 90 degrees angle between the main vessel and side branch. CONCLUSIONS: The modified balloon crush technique can be safely performed, while optimizing side branch access and side branch stent apposition.     

Novel self‐expanding stent system for enhanced provisional bifurcation stenting: Examination by StentBoost and intravascular ultrasound

A 62‐year‐old man underwent percutaneous coronary intervention of a bifurcation lesion (Medina type 010) involving the mid‐left anterior descending coronary artery and an important first diagonal branch with a novel stent specifically designed for bifurcations, the Stentys coronary bifurcation system. This is a self‐expanding nitinol stent, with Z‐shaped struts linked by interconnections that can be disconnected (in prespecified points every 1.5 mm all around the circumference and the length of the stent) at the level of the ostium of the side branch, simply by inflating an angioplasty balloon tracked to the ostium of the side branch, through the stent struts. The steps required for deployment of the stent and the final result obtained were evaluated by intravascular ultrasound examination and StentBoost Subtract, a specific X‐ray stent‐enhancing visualization technique. © 2009 Wiley‐Liss, Inc.     

Analysis of bifurcation lesions treated with novel drug-eluting dedicated bifurcation stent system: intravascular ultrasound results of the AXXESS PLUS trial.

OBJECTIVE: The aim of this intravascular ultrasound (IVUS) study was to assess the efficacy of the AXXESS Plus stent system for the treatment of bifurcation coronary lesions. BACKGROUND: The AXXESS Plus is a novel bifurcation drug-eluting stent, comprised of a self-expanding flare-shaped stent platform and bioabsorbable polymer coating that releases Biolimus A9. METHODS: Data were obtained from the AXXESS PLUS trial, a prospective, multicenter, nonrandomized, single-arm study to evaluate safety and efficacy. Six-month follow-up IVUS analysis was available in 49 cases. Volumetric analysis using Simpson's method within the AXXESS stent, and cross-sectional analysis at the ostium of main branch and/or side branch was performed. Impact of bifurcation angle on stent expansion at the carina was also evaluated. Results: Within the AXXESS stent, neointimal volume obstruction percentage was 2.3% +/- 2.2%, with a minimum lumen area of 7.9 +/- 2.6 mm(2). Lumen area was 5.2 +/- 1.7 mm(2) at main branch ostium, and 4.0 +/- 1.5 mm(2) at side branch ostium. In two cases, incomplete stent apposition was observed at the proximal edge of the AXXESS stent. In one case, a gap between the AXXESS stent and an additional stent was observed. Greater bifurcation angle inversely correlated with smaller stent area at side branch ostium (r = -0.54, P = 0.03) but not at main branch ostium (r = -0.2, P = 0.29). CONCLUSIONS: This novel self-expanding, drug-eluting bifurcation stent demonstrated effective lesion coverage along with significant neointimal suppression equivalent to current generation balloon-expandable drug-eluting stent technology.     

A “Jail Escape Technique” (JET) for distal side branch wiring during provisional stenting: Feasibility and first‐in‐man study

Objective

To evaluate the feasibility of a novel technique for achieving distal SB access and improve strut apposition during provisional stenting.

Background

While distal rewiring and stent expansion toward the side branch (SB) are associated with better results during provisional stenting of coronary artery bifurcation lesions, these techniques are technically challenging and often leave unopposed struts near the carina.

Methods

The “Jail Escape Technique” (JET) is performed by passing the proximal tip of the SB wire between the main vessel (MV) stent struts and balloon before implantation, allowing the MV stent to push the SB wire against the distal part of the carina. The MV stent can then be deployed without jailing the SB wire. Distal SB access and strut distribution at the carina were tested in phantom and swine models. Stent distortion, dislodgement forces, and material damage were evaluated with tensile testing. Human feasibility was then tested on 32 patients.

Results

Preclinical testing demonstrated that the SB wire was located at the most distal part of the carina and no strut malapposition at the carina was present after balloon inflation. Stent distortion, dislodgement forces, or material damage were not affected. JET was successfully performed in 30 of 32 patients. No major adverse cardiovascular events occurred in any patient at 6‐month follow‐up.

Conclusion

The “JET” enables distal SB access and eliminates strut malapposition at the carina. Further studies with larger numbers of patients are needed to further investigate this technique.

     

Double bifurcation lesion treated with double tryton sidebranch stent: First case report

The optimal percutaneous treatment strategy for coronary bifurcation lesions is still unknown. Several dedicated coronary bifurcation stents, such as the Tryton Side Branch Stent^TM (Tryton Medical, Durham, NC) have been developed to improve clinical outcomes. We presented a double bifurcation lesion case treated with two Tryton sidebranch stents, with a single drug eluting stent covering the main vessel and both bifurcations. © 2013 Wiley Periodicals, Inc.     

Inter–Core Lab Variability in Analyzing Quantitative Coronary Angiography for Bifurcation Lesions: A Post-Hoc Analysis of a Randomized Trial

ObjectivesThis study sought to evaluate inter–core lab variability in quantitative coronary angiography (QCA) analysis of bifurcation lesions.BackgroundQCA of bifurcation lesions is challenging. To date there are no data available on the inter–core lab variability of bifurcation QCA analysis.MethodsThe randomized Tryton IDE (Tryton Pivotal IDE Coronary Bifurcation Trial) compared the Tryton Side Branch Stent (Tryton Medical, Durham, North Carolina) with balloon angioplasty as side branch treatment. QCA was performed in an angiographic subcohort (n = 326) at 9-month follow-up. Inter-core lab variability of QCA analysis between the Cardiovascular Research Foundation and the Cardialysis core labs was evaluated before and after alignment of the used QCA methodology using angiographic data derived from this angiographic follow-up cohort.ResultsIn the original analysis, before alignment of QCA methodology, the mean difference between the core labs (bias) was large for all QCA parameters with wide 95% limits of agreement (1.96 × SD of the bias), indicating marked variability. The bias of the key angiographic endpoint of the Tryton trial, in-segment percentage diameter stenosis (%DS) of the side branch, was 5.5% (95% limits of agreement: –26.7% to 37.8%). After reanalysis, the bias of the in-segment %DS of the side branch reduced to 1.8% (95% limits of agreement: –16.7% to 20.4%). Importantly, after alignment of the 2 core labs, there was no longer a difference between both treatment groups (%DS of the side branch: treatment group A vs. group B: 34.4 ± 19.4% vs. 32.4 ± 16.1%, p = 0.340).ConclusionsOriginally, a marked inter–core lab variability of bifurcation QCA analysis was found. After alignment of methodology, inter–core lab variability decreased considerably and impacted angiographic trial results. This latter finding emphasizes the importance of using the same methodology among different core labs worldwide. (Tryton Pivotal Prospective, Single Blind, Randomized Controlled Study to Evaluate the Safety & Effectiveness of the Tryton Side Branch Stent Used With DES in Treatment of de Novo Bifurcation Lesions in the Main Branch & Side Branch in Native Coronaries [TRYTON]; NCT01258972)     

Bail-Out of Stent Jail: Stent Delivery Through Stent Struts

Stent deployment in a lesion with a large side branch is an example of the potential limitation of intracoronary stents, especially the Palmaz-Schatza stent with its tubular slotted design. This case study describes a patient in whom a Palmaz-Schatz stent of excessive length covered the origin of a side branch (òstent jailó). Thrombus developed in the jailed branch as well as in the main vessel, causing abrupt vessel closure and impending acute myocardial infarction within one hour after the procedure. This complication was successfully managed by emergency repeat angioplasty and implantation of a Micro Stenta on both branches, i.e. in the main vessel distal to the Palmaz-Schatz stent and in the side branch through the struts of the Palmaz-Schatz stent.     

Dedicated Tryton Side Branch Stents used in the treatment of coronary bifurcation lesions

IntroductionCoronary bifurcation lesions account for 15–20% of all percutaneous coronary interventions.Dedicated bifurcation stents have recently been introduced with the aim to simplify treatment and improve early and late outcomes following stenting of bifurcation lesions.The purpose of our study was to assess the safety and effectiveness of the Tryton dedicated side branch stent at a 6-month clinical and angiography follow-up.MethodsForty-two patients with bifurcation lesions were included in our study. The primary endpoint was a 6-month MACE and angiographic stent patency was also evaluated by MS-CT coronarography.ResultsTwenty-two patients (52.38%) were treated for acute coronary syndromes, 39 (92.85%) lesions were “true bifurcations”. The 6-month clinical follow-up was performed in all patients. The 6-month MACE rate (cardiac death, myocardial infarction and target lesion revascularization) was 9.52% (95% CI: 2.66–22.62%); of these one patient (2.38%; 95% CI: 0.06–12.57%) died due to cardiogenic shock caused by early stent thrombosis and three patients (7.14%; 95% CI: 1.50–19.48%) required repeated revascularization (TVR) due to in-stent restenosis, all of them in bare metal stents. Tryton stent implantation was successful in 100% lesions.6-Month MS-CT coronarography was performed in 39 (92.85%) patients. The implanted bifurcation Tryton stents were satisfactorily visualized in 97.43% of them and a satisfactory 6-month angiographic patency was demonstrated in 37 patients (88.1%).ConclusionThe usage of a dedicated bifurcation Tryton Side Branch Stent for PCI of the bifurcation lesions is technically feasible with satisfactory long-term results.     

Neointimal coverage and late apposition of everolimus-eluting bioresorbable scaffolds implanted in the acute phase of myocardial infarction: OCT data from the PRAGUE-19 study

Incomplete stent apposition and uncovered struts are associated with a higher risk of stent thrombosis. No data exist on the process of neointimal coverage and late apposition status of the bioresorbable vascular scaffold (BVS) when implanted in the highly thrombogenic setting of ST-segment elevation acute myocardial infarction (STEMI). The aim of this study was to assess the serial changes in strut apposition and early neointimal coverage of the BVS using optical coherence tomography (OCT) in selected patients enrolled in the PRAGUE-19 study. Intracoronary OCT was performed in 50 patients at the end of primary percutaneous coronary intervention for acute STEMI. Repeated OCT of the implanted BVS was performed in 10 patients. Scaffold area, scaffold mean diameter and incomplete strut apposition (ISA) were compared between baseline and control OCT. Furthermore, strut neointimal coverage was assessed during the control OCT. Mean scaffold area and diameter did not change between the baseline and control OCT (8.59 vs. 9.06 mm²; p = 0.129 and 3.31 vs. 3.37 mm; p = 0.202, respectively). Differences were observed in ISA between the baseline and control OCT (0.63 vs. 1.47 %; p < 0.05). We observed 83.1 % covered struts in eight patients in whom the control OCT was performed 4–6 weeks after BVS implantation, and 100 % covered struts in two patients 6 months after BVS implantation. Persistent strut apposition and early neointimal coverage were observed after biodegradable vascular scaffold implantation in patients with acute ST-segment elevation myocardial infarction.     

Theoretical prediction of side branch compromise after main branch stenting in coronary bifurcation

One of the main problems of treatment of bifurcation lesions is side branch (SB) stenosis appearing after stent placement in the main vessel.The aim of this study was to create quantitative method for prediction of side branch compromise extent.We accepted that the main mechanism for SB ostial stenosis is flow divider (FD) displacement from stent struts after stent implantation in the main vessel.Using easily measurable parameters from coronary angiography,as SB diameter,angle α (initial angle between axes of parent vessel and SB axis) and angle α' (angle between above mentioned axes after stent placement) we can calculate percentage diameter stenosis at branch ostium (%DS):%DS = sin (α - α')/(tan α).In boundary condition of full FD displacement %DS = cos α.We tested our theoretical predictions with fluoroscopic observation of elastic wall model of bifurcation (45°distal angle between branches)permitting wall deformations with stent.There is full coincidence of values of %DS and percentage area stenosis (%AS).The regular formulas for calculations of %DS and %AS overestimate stenosis severity between 10% and 25%.Our model tests have shown full coincidence between predicted values for %DS and observed values.We demonstrate that part of the SB ostium is not visible in regular angiography and contributes to ostial lumen area.This is a method that permits quantitative prediction of side branch compromise.