1. Articles in category: Cardiology

    481-504 of 2686 « 1 2 ... 18 19 20 21 22 23 24 ... 110 111 112 »
    1. The qualitative assessment of biodegradable coronary stents with the use of intravascular ultrasound, optical coherence tomography and histology (Thesis)

      The qualitative assessment of biodegradable coronary stents with the use of intravascular ultrasound, optical coherence tomography and histology (Thesis)

      Percutaneous coronary intervention (PCI) is the most common treatment for coronary artery disease (CAD). The first form of PCI introduced was balloon angioplasty. After that, the advent of coronary stents (tubular wire mesh for intravascular mechanical support) led to a new era in interventional cardiology. Through the implantation of bare metal stents (BMS), all three limitations of balloon angioplasty – coronary artery dissection, elastic recoil and negative remodelling – are prevented. Unfortunately, bare metal stents have their own drawbacks: most significantly, in-stent stenosis as a result of deep focal vascular injury caused by stent struts, followed by excessive tissue proliferation. This drawback ...

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    2. Computational Evaluation of Shear Stress and Restenosis in Stented Coronary Arteries Using Optical Coherence Tomography (Thesis)

      Computational Evaluation of Shear Stress and Restenosis in Stented Coronary Arteries Using Optical Coherence Tomography (Thesis)

      The cause of coronary artery neointimal thickness (NT) leading to restenosis in ~10% of drug-eluting stents (DES) is unknown, but adverse wall shear stress (WSS) may contribute. Prior studies comparing WSS to restenosis for first generation DES yielded conflicting results, and cited different mechanisms of action for DES agents. Studies to date have not accounted for stent geometry, which dictates local WSS patterns influencing drug concentration. The objective of this investigation was to evaluate current generation stent platforms via their WSS patterns and their respective impact on NT. We prospectively enrolled 19 patients, who were randomized to thin-strut (81μm ...

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    3. Frequency-Domain Optical Coherence Tomographic Analysis of Plaque Microstructures at Non-culprit Narrowings in Patients Receiving Potent Statin Therapy

      Frequency-Domain Optical Coherence Tomographic Analysis of Plaque Microstructures at Non-culprit Narrowings in Patients Receiving Potent Statin Therapy

      Potent statin therapy has been demonstrated to reduce cardiovascular events. While statins have been considered to stabilize atherosclerotic plaque, this effect has not been well characterized in vivo. We investigated the relationship between potent statin therapy and plaque microstructures imaged by frequency-domain optical coherence tomography (FD-OCT). 290 non-culprit lipid plaques in 275 patients with stable coronary artery disease receiving atorvastatin or rosuvastatin were analyzed. Patients were stratified into no statin, low- and high-dose statin group. Plaques in the high-dose statin group demonstrated a smaller lipid arc (p=0.02) and a greater fibrous cap thickness (p=0.01). In patients ...

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    4. Difference of Ruptured Plaque Morphology between Asymptomatic Coronary Artery Disease and Non-ST Elevation Acute Coronary Syndrome Patients: an Optical Coherence Tomography Study

      Difference of Ruptured Plaque Morphology between Asymptomatic Coronary Artery Disease and Non-ST Elevation Acute Coronary Syndrome Patients: an Optical Coherence Tomography Study

      Background Autopsy studies have reported that rupture of a thin-cap fibroatheroma and subsequent thrombus formation is the major mechanism leading to acute coronary syndrome (ACS). However, it is not clear why only some plaque ruptures lead to ACS. Optical coherence tomography (OCT) is a high-resolution imaging modality which is capable of investigating detailed coronary plaque morphology in vivo. The objective of this study was to determine whether ruptured plaque morphology assessed by OCT differs between asymptomatic coronary artery disease (CAD) and non-ST elevation acute coronary syndrome (NSTEACS). Methods We examined ruptured plaque morphology using OCT in 80 patients, 33 with ...

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    5. Feasibility of Intracoronary Frequency Domain Optical Coherence Tomography Derived Fractional Flow Reserve for the Assessment of Coronary Artery Stenosis

      Feasibility of Intracoronary Frequency Domain Optical Coherence Tomography Derived Fractional Flow Reserve for the Assessment of Coronary Artery Stenosis

      Frequency domain optical coherence tomography (FD-OCT) provides cross-sectional images of coronary arteries and deployed stents with micron resolution and measures lumen dimensions with excellent reproducibility. FD-OCT combined with a blood flow resistances model can overcome many limitations of conventional measures of stenosis severity based on quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS). The aim of this feasibility study was to investigate the relationship between pressure derived fractional flow reserve (FFR) and FD-OCT derived FFR, a new method for quantitative measure of stenosis severity that estimates the blood flow resistance and microvascular resistance of the vessel segments imaged by FD-OCT ...

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    6. Segmentation and quantification for intravascular optical coherence tomography images

      Segmentation and quantification for intravascular optical coherence tomography images

      A system and related methods for automatic or semi-automatic segmentation and quantification of blood vessel structure and physiology, including segmentation and quantification of lumen, guide wire, vessel wall, calcified plaques, fibrous caps, macrophages, metallic and bioresorbable stents are described, and including visualization of results. Calcified plaque segmentation can be used to estimate the distribution of superficial calcification and inform strategies stenting. Volumetric segmentation and quantification of fibrous caps can provide more comprehensive information of the mechanisms behind plaque rupture. Quantification of macrophages can aid diagnosis and prediction of unstable plaque and associated acute coronary events. Automated detection and quantification of ...

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    7. Imaging Plaques to Predict and Better Manage Patients With Acute Coronary Events

      Imaging Plaques to Predict and Better Manage Patients With Acute Coronary Events

      Culprit lesions of patients, who have had an acute coronary syndrome commonly, are ruptured coronary plaques with superimposed thrombus. The precursor of such lesions is an inflamed thin-capped fibroatheroma. These plaques can be imaged by means of invasive techniques, such as intravascular ultrasound (and derived techniques), optical coherence tomography, and near-infrared spectroscopy. Often these patients exhibit similar (multiple) plaques beyond the culprit lesion. These remote plaques can be assessed noninvasively by computed tomographic angiography and MRI and also using invasive imaging. The detection of these remote plaques is not only feasible but also in natural history studies have been associated ...

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    8. Research and Clinical Applications of Optical Coherence Tomography in Invasive Cardiology: A Review

      Research and Clinical Applications of Optical Coherence Tomography in Invasive Cardiology: A Review

      In cardiology, optical coherence tomography (OCT) is an invasive imaging technique based on the principle of light coherence. This system was developed to obtain three-dimensional high resolution images to examine coronary artery normal and/or pathological structure. This technique replaces the ultrasound used by its main alternative procedure, intravascular ultrasound, by a near-infrared light source. Acute coronary syndromes due to atherosclerotic vascular disease are the leading cause of mortality in developed and developing countries. As a consequence, intravascular imaging systems became an important area of research and 1991 marks the first use of OCT in coronary artery observations. Since its ...

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    9. Two Different Mechanisms of Very Late Stent Thrombosis: Assessment and Guidance of Therapy with Optical Coherence Tomography

      Two Different Mechanisms of Very Late Stent  Thrombosis: Assessment and Guidance of Therapy  with Optical Coherence Tomography

      Incomplete coverage of stent struts and atherosclerosis within the neointima are the two most frequently mechanisms of very late stent thrombosis (VLST). As the determination by conventional coronary angiography is not always possible, the use of optical coherence tomography (OCT) is getting more and more important. The high resolution of OCT allows a closer look to the pathomechanisms of VLST, which helps to make the right decisions in the catheterization laboratory. These cases demonstrate the evaluation of VLST by OCT and the resulting therapeutical decisions.

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    10. Bifurcated Lesions and Optical Coherence Tomography

      Bifurcated Lesions and Optical Coherence Tomography

      Coronary artery bifurcation lesions constitute a complex subgroup that are encountered in 15–20 % of all percutaneous coronary interventions (PCI). 1–5 Compared with simple lesions, bifurcations have been associated with lower procedural success rates, higher adverse event rates, longer procedures, and worse angiographic and clinical outcomes. 1,3,5–12 The less favourable outcomes associated with bifurcation treatment compared with non-bifurcation lesions may in part result from the inability of current devices and techniques to adequately scaffold and preserve the side branch (SB) ostium, which is a common location of restenosis. 1,3,5–13

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    11. OCT Findings from the European Multi-centre Prestige Stent Thrombosis Study

      OCT Findings from the European Multi-centre Prestige Stent Thrombosis Study

      Background Coronary stent thrombosis (ST) remains the ‘Achilles Heel’ of percutaneous coronary intervention (PCI). Although relatively rare, it is associated with a high rate of acute myocardial infarction and death.A specific point of concern is the ongoing risk of very late ST, occurring more than one year after stent implantation, and the fact that this seems to occur steadily at an annual rate of 0.5% with a high risk of recurrence. The exact mechanisms are multi-factorial and poorly understood and previous studies have been hampered by small sample sizes, incomplete patient characterisation, and a lack of intracoronary imaging ...

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      Mentions: St. Jude Medical
    12. Feasibility of Optical Coherence Tomography in Children with Kawasaki Disease and Pediatric Heart Transplant Recipients

      Feasibility of Optical Coherence Tomography in Children with Kawasaki Disease and Pediatric Heart Transplant Recipients

      Background —Optical Coherence Tomography (OCT) is a high-resolution intravascular imaging technique used in adults. We tested the hypothesis that OCT could identify coronary abnormalities not seen by angiography in children with a history of Kawasaki Disease (KD) and pediatric heart transplant (TX) recipients. Methods and Results —KD patients and TX recipients were evaluated between December 2012 and October 2013 with angiography and OCT (Ilumien System, LightLabs, St Jude Medical, Westford, MA). Modifications were made to the adult OCT protocol to adapt this technique for children. Serial cross sectional area (CSA) measurements of the lumen, intima and media were made. Entire ...

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    13. Optical coherence tomography and intravascular ultrasound of double kissing crush coronary bifurcation stenting

      Optical coherence tomography and intravascular ultrasound of double kissing crush coronary bifurcation stenting

      A 55-year-old male underwent percutaneous coronary intervention (PCI) of a Medina 1,1,1 circumflex (LCx) and a first obtuse marginal (OM1) bifurcation lesion. A double kissing crush technique was performed, utilising a 2.75×12 mm everolimus-eluting stent (EES) in OM1 and a XIENCE V 4.0×15 mm EES (Abbott Vascular, Santa Clara, CA, USA) in the LCx (Online Figure 1). Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) runs were performed (Online Figure 2, Online Figure 3, Moving image 1). 3D reconstruction of the OCT further clarified the reconstruction of the bifurcation carina and paving, in particular ...

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    14. Noncontact quantitative biomechanical characterization of cardiac muscle using shear wave imaging optical coherence tomography

      Noncontact quantitative biomechanical characterization of cardiac muscle using shear wave imaging optical coherence tomography

      We report on a quantitative optical elastographic method based on shear wave imaging optical coherence tomography (SWI-OCT) for biomechanical characterization of cardiac muscle through noncontact elasticity measurement. The SWI-OCT system employs a focused air-puff device for localized loading of the cardiac muscle and utilizes phase-sensitive OCT to monitor the induced tissue deformation. Phase information from the optical interferometry is used to reconstruct 2-D depth-resolved shear wave propagation inside the muscle tissue. Cross-correlation of the displacement profiles at various spatial locations in the propagation direction is applied to measure the group velocity of the shear waves, based on which the Young ...

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    15. Interpretation of optical coherence tomography images : The Lancet

      Interpretation of optical coherence tomography images : The Lancet

      We read with great interest the Clinical Picture reported by Dennis Wong and colleagues (Feb 8, p e11) 1 who took advantage of the unprecedented resolution of optical coherence tomography (OCT) to identify the culprit lesion and guide coronary stenting in a patient with acute myocardial infarction. Over the last decade, OCT has become the method of choice to investigate the mechanisms responsible for acute coronary syndromes. 2 In this report, 1 the authors describe a ruptured thin-cap fibroatheroma with overlying thrombus as cause of acute coronary syndrome. However, this observation raises some important issues. Plaque rupture is typically detected ...

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    16. Interpretation of optical coherence tomography images – Authors' reply

      Interpretation of optical coherence tomography images – Authors' reply

      We would like to express our gratitude for the feedback that we received following our Clinical Picture 1 on a potential ruptured plaque and intracoronary thrombus. We acknowledge the concerns raised about our initial interpretation of the optical coherence tomography (OCT) images. Image interpretation remains the Achilles' heel of interventional cardiology with invasive intracoronary imaging, but must also always be done in the context of the clinical scenario. In our Clinical Picture, 1 a patient who had a recent non-ST segment elevation myocardial infarction had a hazy severe stenosis in the first diagonal artery on coronary angiography. This was then ...

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    17. Searching Between the Plaques Layers to Understand the Past and Predict the Future ∗

      Searching Between the Plaques Layers to Understand the Past and Predict the Future ∗

      The layers of the earth and the fossils hidden within the rocks reveal to the geologist the secrets of the past, sending him back for a trip millions of years long. Pathologists and nowadays cardiologists try to do the same, interrogating the vessel wall and atherosclerotic plaques, looking for the missing pieces of the complex puzzle that determine the pathophysiology of myocardial infarction and sudden death. Tian et al. 1 should be congratulated for their effort to collect new insights on the “in vivo” anatomy of coronary lesions, using a complex approach combining intravascular ultrasound and optical coherence tomography (OCT ...

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      Mentions: Francesco Prati
    18. Does optical coherence tomography optimize results of stenting? Rationale and study design.

      Does optical coherence tomography optimize results of stenting? Rationale and study design.

      Background To date, no randomized study has investigated the value of optical coherence tomography (OCT) in optimizing the results of coronary angioplasty for non-ST elevation acute coronary syndromes (NSTE-ACS). Methods DOCTORS is a randomized, prospective, multicentre, open-label clinical trial to evaluate the utility of OCT to optimize results of angioplasty of a lesion responsible for NSTE-ACS. Patients (n = 250) will be randomized to undergo OCT-guided angioplasty (use of OCT to optimise procedural result, including change to strategy with the possibility of additional interventions); or angioplasty under fluoroscopy alone. The primary endpoint is the functional result of the angioplasty procedure as ...

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    19. Development of Optical Coherence Tomography for Quantitative Analysis of Cardiac Morphology (Thesis)

      Development of Optical Coherence Tomography for Quantitative Analysis of Cardiac Morphology (Thesis)

      Transgenic mouse models have been instrumental in the elucidation of the molecular mechanism behind many cardiac diseases such as Marfan syndrome. However, the small size of the murine heart has hampered the characterization of its cardiac morphology. In this project, we describe the development of a murine cardiac imaging modality using optical coherence tomography (OCT). After fixation and optical clearing, the hearts were imaged from multiple perspectives. These data sets were then corrected for refraction and registered together to yield a single volume of the whole heart. From this OCT volume, we then applied techniques from computational anatomy to quantify ...

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    20. Serial 2-Dimensional and 3-Dimensional Optical Coherence Tomography Assessment of Overhanging Struts of Drug-Eluting Absorbable Metal Scaffold

      Serial 2-Dimensional and 3-Dimensional Optical Coherence Tomography Assessment of Overhanging Struts of Drug-Eluting Absorbable Metal Scaffold

      A 75-year-old woman with stable angina pectoris underwent percutaneous coronary intervention of the left anterior descending coronary artery, whereby a 3.25/16-mm paclitaxel-eluting absorbable metal scaffold (DREAMS, Biotronik, Bülach, Switzerland) was successfully implanted. Post-procedural angiography showed excellent results without pinching of the side branch ostium. The patient experienced no procedure-related complications, and was discharged 48 h after the procedure on dual antiplatelet therapy. Optical coherence tomography (OCT) (LightLab Imaging, Westford, Massachusetts) was performed post-procedure and at 12 months follow-up. Post-procedurally, the scaffold was well expanded with good apposition of struts to the vessel wall, and a side branch ...

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    21. Patient-Specific Coronary Stenoses Can Be Modeled Using a Combination of OCT and Flow Velocities to Accurately Predict Hyperemic Pressure Gradients

      Patient-Specific Coronary Stenoses Can Be Modeled Using a Combination of OCT and Flow Velocities to Accurately Predict Hyperemic Pressure Gradients

      Computational fluid dynamics (CFD) is increasingly being developed for the diagnostics of arterial diseases. Imaging methods such as computed tomography (CT) and angiography are commonly used. However, these have limited spatial resolution and are subject to movement artifact. This study developed a new approach to generate CFD models by combining high-fidelity, patient-specific coronary anatomy models derived from optical coherence tomography (OCT) imaging with patient-specific pressure and velocity phasic data. Additionally, we used a new technique which does not require the catheter to be used to determine the centerline of the vessel. The CFD data were then compared with invasively measured ...

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

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

      Objectives This study sought to evaluate the relationship between post-stent strut apposition and follow-up strut coverage using contour plot optical coherence tomographic analysis. Background Tracking the fate of interested regions of struts at different time points has not been investigated. Methods 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 ...

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