1. Articles from Christos V. Bourantas

    1-24 of 30 1 2 »
    1. Utility of Multimodality Intravascular Imaging and the Local Hemodynamic Forces to Predict Atherosclerotic Disease Progression

      Utility of Multimodality Intravascular Imaging and the Local Hemodynamic Forces to Predict Atherosclerotic Disease Progression

      Objectives This study sought to examine the utility of multimodality intravascular imaging and of the endothelial shear stress (ESS) distribution to predict atherosclerotic evolution. Background There is robust evidence that intravascular ultrasound (IVUS)-derived plaque characteristics and ESS distribution can predict, with however limited accuracy, atherosclerotic evolution; nevertheless, it is yet unclear whether multimodality imaging and ESS mapping enable more accurate prediction of coronary plaque progression. Methods A total of 44 patients admitted with a myocardial infarction that had successful revascularization and 3-vessel IVUS and optical coherence tomography (OCT) imaging at baseline and 13-month follow-up were included in the study ...

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    2. Efficacy and Reproducibility of Attenuation-Compensated Optical Coherence Tomography for Assessing External Elastic Membrane Border and Plaque Composition in Native and Stented Segments ― An In Vivo and Histology-Based Study ―

      Efficacy and Reproducibility of Attenuation-Compensated Optical Coherence Tomography for Assessing External Elastic Membrane Border and Plaque Composition in Native and Stented Segments ― An In Vivo and Histology-Based Study ―

      Background: Attenuation-compensated (AC) technique was recently introduced to improve the plaque characterization of optical coherence tomography (OCT). Histological validation demonstrated promising results but the efficacy and reproducibility of this technique for assessing in-vivo tissue composition remains unclear. Methods and Results: OCT images portraying native (n=200) and stented (n=200) segments and 31 histological cross-sections were analyzed. AC-OCT appeared superior to conventional (C)-OCT in detecting the external elastic lamina (EEM) borders (76% vs. 65.5%); AC-OCT enabled larger EEM arc detection compared with C-OCT (174.2±58.7° vs. 137.5±57.9°; P<0.001). There was poor ...

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    3. Optical coherence tomography enables more accurate detection of functionally significant intermediate non-left main coronary artery stenoses than intravascular ultrasound: A meta-analysis of 6919 patients and 7537 lesions

      Optical coherence tomography enables more accurate detection of functionally significant intermediate non-left main coronary artery stenoses than intravascular ultrasound: A meta-analysis of 6919 patients and 7537 lesions

      Objective Fractional flow reserve (FFR) is regarded as the gold standard for the physiological assessment of intermediate coronary artery stenoses. However, FFR does not allow assessment of plaque morphology and lesion geometry. Intracoronary imaging techniques such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT) can help treatment planning by optimising stent implantation, which can improve patient outcomes. The aim of this meta-analysis is to compare the efficacy of IVUS and OCT-derived metrics in detecting flow limiting stenoses in non-left main stem lesions. Methods A systematic review of PubMed, Medline, and Cochrane databases was performed and identified studies examining the ...

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    4. Clinical use of intracoronary imaging. Part 2: acute coronary syndromes, ambiguous coronary angiography findings, and guiding interventional decision-making: an expert consensus document of the European Association of Percutaneous Cardiovascular Intervent

      Clinical use of intracoronary imaging. Part 2: acute coronary syndromes, ambiguous coronary angiography findings, and guiding interventional decision-making: an expert consensus document of the European Association of Percutaneous Cardiovascular Intervent

      This consensus document is the second of two reports summarizing the views of an expert panel organized by the European Association of Percutaneous Cardiovascular Interventions (EAPCI) on the clinical use of intracoronary imaging including intravascular ultrasound (IVUS), optical coherence tomography (OCT), and near infrared spectroscopy (NIRS)-IVUS. Beyond guidance of stent selection and optimization of deployment, invasive imaging facilitates angiographic interpretation and may guide treatment in acute coronary syndrome. Intravascular imaging can provide additional important diagnostic information when confronted with angiographically ambiguous lesions and allows assessment of plaque morphology enabling identification of vulnerability characteristics. This second document focuses on useful ...

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    5. Feature Of The Week 08/01/2018: OCT Shows Promise in Effecting Outcomes after Coronary Intervention Being Associated with Improved Long-Term Survival

      Feature Of The Week 08/01/2018: OCT Shows Promise in Effecting Outcomes after Coronary Intervention Being Associated with Improved Long-Term Survival

      Objectives This study aimed to determine the effect on long-term survival of using optical coherence tomography (OCT) during percutaneous coronary intervention (PCI). Background Angiographic guidance for PCI has substantial limitations. The superior spatial resolution of OCT could translate into meaningful clinical benefits, although limited data exist to date about their effect on clinical endpoints. Methods This was a cohort study based on the Pan-London (United Kingdom) PCI registry, which includes 123,764 patients who underwent PCI in National Health Service hospitals in London between 2005 and 2015. Patients undergoing primary PCI or pressure wire use were excluded leaving 87,166 ...

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    6. Angiography Alone Versus Angiography Plus Optical Coherence Tomography to Guide Percutaneous Coronary Intervention: Outcomes From the Pan-London PCI Cohort

      Angiography Alone Versus Angiography Plus Optical Coherence Tomography to Guide Percutaneous Coronary Intervention: Outcomes From the Pan-London PCI Cohort

      Objectives This study aimed to determine the effect on long-term survival of using optical coherence tomography (OCT) during percutaneous coronary intervention (PCI). Background Angiographic guidance for PCI has substantial limitations. The superior spatial resolution of OCT could translate into meaningful clinical benefits, although limited data exist to date about their effect on clinical endpoints . Methods This was a cohort study based on the Pan-London (United Kingdom) PCI registry, which includes 123,764 patients who underwent PCI in National Health Service hospitals in London between 2005 and 2015. Patients undergoing primary PCI or pressure wire use were excluded leaving 87,166 ...

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    7. Coronary calcification as a mechanism of plaque/media shrinkage in vessels treated with bioresorbable vascular scaffold: A multimodality intracoronary imaging study

      Coronary calcification as a mechanism of plaque/media shrinkage in vessels treated with bioresorbable vascular scaffold: A multimodality intracoronary imaging study

      Background and aims Whether coronary calcification is correlated with plaque/media shrinkage (PS) remains unclear. The aim of this study was to assess the relationship between the calcification process and PS, combining serial optical coherence tomography (OCT) and intravascular ultrasound (IVUS) in vessels treated with bioresorbable vascular scaffolds (BVS). Methods In 15 patients (16 vessels), OCT and IVUS images were matched using anatomic landmarks at post-procedure and five years. PS was defined as relative decrease in plaque/media area >5%. The association between the calcification process and PS was investigated. Mixed effects model was used to assess correlations and changes ...

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    8. Hemodynamic analysis of a novel bioresorbable scaffold in porcine coronary artery model

      Hemodynamic analysis of a novel bioresorbable scaffold in porcine coronary artery model

      Background The shear stress distribution assessment can provide useful insights for the hemodynamic performance of the implanted stent/scaffold. Our aim was to investigate the effect of a novel bioresorbable scaffold, Mirage on local hemodynamics in animal models. Method The main epicardial coronary arteries of 7 healthy mini-pigs were implanted with 11 Mirage Microfiber sirolimus-eluting Bioresorbable Scaffolds (MMSES). Optical coherence tomography (OCT) was performed post scaffold implantation and the obtained images were fused with angiographic data to reconstruct the coronary artery anatomy. Blood flow simulation was performed and Endothelial Shear Stress(ESS) distribution was estimated for each of the 11 ...

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    9. Non-Newtonian pulsatile shear stress assessment: a method to differentiate bioresorbable scaffold platforms

      Non-Newtonian pulsatile shear stress assessment: a method to differentiate bioresorbable scaffold platforms

      In-vitro and in-sili co studies have shown that the implantation of coronary stent or scaffold induces changes in local haemodynamic microenvironment. Coronary angiography and optical coherence tomography (OCT) data were used to perform three-dimensional reconstruction of the right coronary of two healthy mini pigs after implantation of a 3.0 × 18 mm Absorb BVS with strut thickness of 157 µm (Abbott Vascular, USA) and 3.0 × 14 mm ArterioSorb with strut thickness of 95 µm (Arterius, UK) ( Figure ). Computational fluid dynamic (CFD) techniques were implemented to simulate pulsatile coronary blood flow. Quemada equation was implemented for shear-thinning blood rheology which ...

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    10. Hybrid intravascular imaging: recent advances, technical considerations, and current applications in the study of plaque pathophysiology

      Hybrid intravascular imaging: recent advances, technical considerations, and current applications in the study of plaque pathophysiology

      Cumulative evidence from histology-based studies demonstrate that the currently available intravascular imaging techniques have fundamental limitations that do not allow complete and detailed evaluation of plaque morphology and pathobiology, limiting the ability to accurately identify high-risk plaques. To overcome these drawbacks, new efforts are developing for data fusion methodologies and the design of hybrid, dual-probe catheters to enable accurate assessment of plaque characteristics, and reliable identification of high-risk lesions. Today several dual-probe catheters have been introduced including combined near infrared spectroscopy-intravascular ultrasound (NIRS-IVUS), that is already commercially available, IVUS-optical coherence tomography (OCT), the OCT-NIRS, the OCT-near infrared fluorescence (NIRF) molecular ...

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    11. Biomechanical stress in coronary atherosclerosis: emerging insights from computational modelling

      Biomechanical stress in coronary atherosclerosis: emerging insights from computational modelling

      Coronary plaque rupture is the most common cause of vessel thrombosis and acute coronary syndrome. The accurate early detection of plaques prone to rupture may allow prospective, preventative treatment; however, current diagnostic methods remain inadequate to detect these lesions. Established imaging features indicating vulnerability do not confer adequate specificity for symptomatic rupture. Similarly, even though experimental and computational studies have underscored the importance of endothelial shear stress in progressive atherosclerosis, the ability of shear stress to predict plaque progression remains incremental. This review examines recent advances in image-based computational modelling that have elucidated possible mechanisms of plaque progression and rupture ...

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    12. Bioresorbable vascular scaffold treatment induces the formation of neointimal cap that seals the underlying plaque without compromising the luminal dimensions: a concept based on serial optical coherence tomography data

      Bioresorbable vascular scaffold treatment induces the formation of neointimal cap that seals the underlying plaque without compromising the luminal dimensions: a concept based on serial optical coherence tomography data

      Aims: To evaluate the implications of an Absorb bioresorbable vascular scaffold (Absorb BVS) on the morphology of the superficial plaques. Methods and results: Forty-six patients who underwent Absorb BVS implantation and 20 patients implanted with bare metal stents (BMS) who had serial optical coherence tomographic examination at baseline and follow-up were included in this analysis. The thin-capped fibroatheromas (TCFA) were identified in the device implantation regions and in the adjacent native coronary segments. Within all regions, circumferential locations of TCFA and calcific tissues were identified, and the neointimal thickness was measured at follow-up. At six to 12-month follow-up, only 8 ...

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    13. Error propagation in the characterization of atheromatic plaque types based on imaging

      Error propagation in the characterization of atheromatic plaque types based on imaging

      Imaging systems transmit and acquire signals and are subject to errors including: error sources, signal variations or possible calibration errors. These errors are included in all imaging systems for atherosclerosis and are propagated to methodologies implemented for the segmentation and characterization of atherosclerotic plaque. In this paper, we present a study for the propagation of imaging errors and image segmentation errors in plaque characterization methods applied to 2D vascular images. More specifically, the maximum error that can be propagated to the plaque characterization results is estimated, assuming worst-case scenarios. The proposed error propagation methodology is validated using methods applied to ...

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    14. Scaffold and Edge Vascular Response Following Implantation of Everolimus-Eluting Bioresorbable Vascular Scaffold : A 3-Year Serial Optical Coherence Tomography Study

      Scaffold and Edge Vascular Response Following Implantation of Everolimus-Eluting Bioresorbable Vascular Scaffold : A 3-Year Serial Optical Coherence Tomography Study

      Objectives This study sought to investigate the in-scaffold vascular response (SVR) and edge vascular response (EVR) after implantation of an everolimus-eluting bioresorbable scaffold (BRS) using serial optical coherence tomography (OCT) imaging. Background Although studies using intravascular ultrasound have evaluated the EVR in metal stents and BRSs, there is a lack of OCT-based SVR and EVR assessment after BRS implantation. Methods In the ABSORB Cohort B (ABSORB Clinical Investigation, Cohort B) study, 23 patients (23 lesions) in Cohort B1 and 17 patients (18 lesions) in Cohort B2 underwent truly serial OCT examinations at 3 different time points (Cohort B1: post-procedure, 6 ...

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    15. Bioresorbable vascular scaffold treatment induces the formation of neointimal cap that seals the underlying plaque without compromising the luminal dimensions: a concept based on serial optical coherence tomography data

      Bioresorbable vascular scaffold treatment induces the formation of neointimal cap that seals the underlying plaque without compromising the luminal dimensions: a concept based on serial optical coherence tomography data

      Aims: To evaluate the implications of an Absorb bioresorbable vascular scaffold (Absorb BVS) on the morphology of the superficial plaques. Methods and results: Forty-six patients who underwent Absorb BVS implantation and 20 patients implanted with bare metal stents (BMS) who had serial optical coherence tomographic examination at baseline and follow-up were included in this analysis. The thin-capped fibroatheromas (TCFA) were identified in the device implantation regions and in the adjacent native coronary segments. Within all regions, circumferential locations of TCFA and calcific tissues were identified, and the neointimal thickness was measured at follow-up. At six to 12-month follow-up, only 8 ...

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    16. Endothelial Shear Stress and Coronary Plaque Characteristics in Humans: A Combined Frequency-Domain Optical Coherence Tomography and Computational Fluid Dynamics Study

      Endothelial Shear Stress and Coronary Plaque Characteristics in Humans: A Combined Frequency-Domain Optical Coherence Tomography and Computational Fluid Dynamics Study

      Background —Despite the exposure of the entire vasculature to the atherogenic effects of systemic risk factors, atherosclerotic plaques preferentially develop at sites with disturbed flow. This study aimed at exploring in vivo the relationship between local endothelial shear stress (ESS) and coronary plaque characteristics in humans, using computational fluid dynamics and frequency-domain optical coherence tomography (FD-OCT). Methods and Results —Three-dimensional coronary artery reconstruction was performed in 21 patients (24 arteries) presenting with acute coronary syndrome using FD-OCT and coronary angiography. Each coronary artery was divided into sequential 3-mm segments, and analyzed for the assessment of local ESS and plaque characteristics ...

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    17. Currently available methodologies for the processing of intravascular ultrasound and optical coherence tomography images

      Currently available methodologies for the processing of intravascular ultrasound and optical coherence tomography images

      Optical coherence tomography and intravascular ultrasound are the most widely used methodologies in clinical practice as they provide high resolution cross-sectional images that allow comprehensive visualization of the lumen and plaque morphology. Several methods have been developed in recent years to process the output of these imaging modalities, which allow fast, reliable and reproducible detection of the luminal borders and characterization of plaque composition. These methods have proven useful in the study of the atherosclerotic process as they have facilitated analysis of a vast amount of data. This review presents currently available intravascular ultrasound and optical coherence tomography processing methodologies ...

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    18. Incomplete Stent Apposition Causes High Shear Flow Disturbances and Delay in Neointimal Coverage as a Function of Strut to Wall Detachment Distance: Implications for the Management of Incomplete Stent Apposition

      Incomplete Stent Apposition Causes High Shear Flow Disturbances and Delay in Neointimal Coverage as a Function of Strut to Wall Detachment Distance: Implications for the Management of Incomplete Stent Apposition

      BACKGROUND: Lack of re-endothelialization and neointimal coverage on stent struts has been put forward as the main underlying mechanism leading to late stent thrombosis. Incomplete stent apposition (ISA) has been observed frequently in patients with very late stent thrombosis after drug eluting stent implantation, suggesting a role of ISA in the pathogenesis of this adverse event. The aim of this study was to evaluate the impact of different degrees of ISA severity on abnormal shear rate and healing response with coverage, because of its potential implications for stent optimization in clinical practice. METHODS AND RESULTS: We characterized flow profile and ...

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    19. Effect of the Endothelial Shear Stress Patterns on Neointimal Proliferation Following Drug-Eluting Bioresorbable Vascular Scaffold Implantation : An Optical Coherence Tomography Study

      Effect of the Endothelial Shear Stress Patterns on Neointimal Proliferation Following Drug-Eluting Bioresorbable Vascular Scaffold Implantation : An Optical Coherence Tomography Study

      Objectives The goal of this study was to investigate the effect of endothelial shear stress (ESS) on neointimal formation following an Absorb bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, California) implantation. Background Cumulative evidence, derived from intravascular ultrasound–based studies, has demonstrated a strong association between local ESS patterns and neointimal formation in bare-metal stents, whereas in drug-eluting stents, there are contradictory data about the effect of ESS on the vessel wall healing process. The effect of ESS on neointimal development following a bioresorbable scaffold implantation remains unclear. Methods Twelve patients with an obstructive lesion in a relatively straight ...

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    20. Methodology for fully automated segmentation and plaque characterization in intracoronary optical coherence tomography images

      Methodology for fully automated segmentation and plaque characterization in intracoronary optical coherence tomography images

      Optical coherence tomography (OCT) is a light-based intracoronary imaging modality that provides high-resolution cross-sectional images of the luminal and plaque morphology. Currently, the segmentation of OCT images and identification of the composition of plaque are mainly performed manually by expert observers. However, this process is laborious and time consuming and its accuracy relies on the expertise of the observer. To address these limitations, we present a methodology that is able to process the OCT data in a fully automated fashion. The proposed methodology is able to detect the lumen borders in the OCT frames, identify the plaque region, and detect ...

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    21. Fusion of optical coherence tomographic and angiographic data for more accurate evaluation of the endothelial shear stress patterns and neointimal distribution after bioresorbable scaffold implantation: comparison with intravascular ultrasound-derived rec

      Fusion of optical coherence tomographic and angiographic data for more accurate evaluation of the endothelial shear stress patterns and neointimal distribution after bioresorbable scaffold implantation: comparison with intravascular ultrasound-derived rec

      Intravascular ultrasound (IVUS)-based reconstructions have been traditionally used to examine the effect of endothelial shear stress (ESS) on neointimal formation. The aim of this analysis is to compare the association between ESS and neointimal thickness (NT) in models obtained by the fusion of optical coherence tomography (OCT) and coronary angiography and in the reconstructions derived by the integration of IVUS and coronary angiography. We analyzed data from six patients implanted with an Absorb bioresorbable vascular scaffold that had biplane angiography, IVUS and OCT investigation at baseline and 6 or 12 months follow-up. The IVUS and OCT follow-up data were ...

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    22. Fully automated calcium detection using optical coherence tomography

      Fully automated calcium detection using optical coherence tomography

      Optical Coherence Tomography (OCT) is a new invasive technology for performing high-resolution cross-sectional imaging of the coronary arteries. In OCT images only Calcified plaque (CA) components can be accurately depicted as light penetrates hard tissue. In this work we present an automated method for detecting CA in OCT images. The method is fully automated as no user intervention is needed and includes three steps. In the first step the region between the lumen and the maximum penetration depth of OCT from the lumen border is determined. In the second step the region is classified into 3 clusters using the K-means ...

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    23. New Developments in Hybrid Optical Coherence Tomographic Imaging: Current Status and Potential Implications in Clinical Practice and Research

      New Developments in Hybrid Optical Coherence Tomographic Imaging: Current Status and Potential Implications in Clinical Practice and Research

      Optical coherence tomography (OCT) is a relatively new imaging technique that was introduced to overcome limitations of previous imaging modalities. OCT provides high resolution cross-sectional images of the coronaries which permit detailed evaluation of the luminal morphology and assessment of coronary artery pathology. These unique qualities render OCT a useful tool in clinical practice and research arena. However, apart from its significant advantages OCT imaging has also considerable limitations. To overcome the pitfalls of OCT, fusion of this modality with other imaging techniques has been proposed. Today several hybrid catheter and sophisticated data fusion methodologies have been developed for this ...

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    24. In vivo assessment of the three-dimensional haemodynamic micro-environment following drug-eluting bioresorbable vascular scaffold implantation in a human coronary artery: fusion of frequency domain optical coherence tomography and angiography

      In vivo assessment of the three-dimensional haemodynamic micro-environment following drug-eluting bioresorbable vascular scaffold implantation in a human coronary artery: fusion of frequency domain optical coherence tomography and angiography

      The biplane angiographic data, acquired after implantation of an everolimus-eluting bioresorbable vascular scaffold (Absorb™ BVS; Abbott Vascular, Santa Clara, CA, USA) in the right coronary artery of a 46-year-old patient, were separately fused with frequency domain optical coherence tomography (FD-OCT) and intravascular ultrasound (IVUS) data to reconstruct the three-dimensional (3-D) anatomy. The local shear stress (SS) distribution in the FD-OCT- and IVUS-based models was assessed using computational fluid dynamics. The FD-OCT-based reconstruction (Figure 1A) allowed imaging of the lumen irregularities in the scaffolded segment due to strut protrusion (Figure 1B), which caused recirculation zones around the struts (Figure 1C). In ...

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    1. (30 articles) Christos V. Bourantas
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    Focus on the research utility of intravascular ultrasound - comparison with other invasive modalities Fusion of optical coherence tomography and coronary angiography — In vivo assessment of shear stress in plaque rupture In vivo three dimensional optical coherence tomography. A novel imaging modality to visualize the edge vascular response Edge Vascular Response After Percutaneous Coronary Intervention : An Intracoronary Ultrasound and Optical Coherence Tomography Appraisal: From Radioactive Platforms to First- and Second-Generation Drug-Eluting Stents and Bioresorbable Scaffolds Intracoronary Optical Coherence Tomography and Histology of Overlapping Everolimus-Eluting Bioresorbable Vascular Scaffolds in a Porcine Coronary Artery Model : The Potential Implications for Clinical Practice In vivo assessment of the three-dimensional haemodynamic micro-environment following drug-eluting bioresorbable vascular scaffold implantation in a human coronary artery: fusion of frequency domain optical coherence tomography and angiography New Developments in Hybrid Optical Coherence Tomographic Imaging: Current Status and Potential Implications in Clinical Practice and Research Hybrid intravascular imaging: recent advances, technical considerations, and current applications in the study of plaque pathophysiology Angiography Alone Versus Angiography Plus Optical Coherence Tomography to Guide Percutaneous Coronary Intervention: Outcomes From the Pan-London PCI Cohort Feature Of The Week 08/01/2018: OCT Shows Promise in Effecting Outcomes after Coronary Intervention Being Associated with Improved Long-Term Survival Line-field confocal optical coherence tomography-Practical applications in dermatology and comparison with established imaging methods Optical coherence tomography detection of changes in inner retinal and choroidal thicknesses in patients with early retinitis pigmentosa