Decline of Low-Frequency Hearing in People With Ski-Slope Hearing Loss; Implications for Electrode Array Insertion.

Hypothesis: The decline of low-frequency hearing in people with ski-slope hearing loss varies and might depend on etiology.

Background: People with ski-sloping hearing loss might benefit from cochlear implantation with preservation of residual hearing. To reduce the risk of losing low-frequency hearing after implantation, the electrode-array can be inserted partially up to the desired frequency.

OCT-measured plaque free wall angle is indicative for plaque burden: overcoming the main limitation of OCT?

The aim of this study was to investigate the relationship between the plaque free wall (PFW) measured by optical coherence tomography (OCT) and the plaque burden (PB) measured by intravascular ultrasound (IVUS). We hypothesize that measurement of the PFW could help to estimate the PB, thereby overcoming the limited ability of OCT to visualize the external elastic membrane in the presence of plaque. This could enable selection of the optimal stent-landing zone by OCT, which is traditionally defined by IVUS as a region with a PB < 40 %.

High shear stress relates to intraplaque haemorrhage in asymptomatic carotid plaques.

Background And Aims: Carotid artery plaques with vulnerable plaque components are related to a higher risk of cerebrovascular accidents. It is unknown which factors drive vulnerable plaque development. Shear stress, the frictional force of blood at the vessel wall, is known to influence plaque formation.

Positive remodeling at 3 year follow up is associated with plaque-free coronary wall segment at baseline: a serial IVUS study.

Aims: At present it is unknown what limits the arterial remodeling process during atherosclerotic plaque formation. In healthy arteries remodeling is regulated by the shear stress induced response by the endothelium. As endothelium at the plaque site is assumed to be dysfunctional, we tested the hypothesis that plaque free wall (PFW) determines vascular remodeling during atherosclerotic plaque build-up.

A CT-based Medina classification in coronary bifurcations: does the lumen assessment provide sufficient information?

Aims: To evaluate the distribution of atherosclerosis at bifurcations with computed tomography coronary angiography (CTCA) and propose a novel CT-Medina classification for bifurcation lesions.

Methods: In 26 patients (age 55 ± 10 years, 81% male) imaged with CTCA, 39 bifurcations were studied. The bifurcations analysis included the proximal main vessel, the distal main vessel and the side branch (SB).

3D reconstruction techniques of human coronary bifurcations for shear stress computations.

Background: Heterogeneity in plaque composition in human coronary artery bifurcations is associated with blood flow induced shear stress. Shear stress is generally determined by combing 3D lumen data and computational fluid dynamics (CFD). We investigated two new procedures to generate 3D lumen reconstructions of coronary artery bifurcations for shear stress computations.

Advanced three-dimensional quantitative coronary angiographic assessment of bifurcation lesions: methodology and phantom validation.

Aims: Validation of new three-dimensional (3-D) bifurcation quantitative coronary angiography (QCA) software.

Methods And Results: Cardiovascular Angiography Analysis System (CAAS 5v10) allows 3-D angiographic reconstructions based on two or more 2-D projection images. Measurements for minimal lumen diameter (MLD), reference vessel diameter (RVD), percent diameter stenosis (DS) and bifurcation angle (BA) were validated against precision manufactured phantom bifurcations.

In vivo assessment of the relationship between shear stress and necrotic core in early and advanced coronary artery disease.

Aims: Atherosclerotic plaques develop at low shear stress locations in the arterial tree. However, at a certain moment, plaques encroach into the lumen causing local wall shear stress (WSS) increase. Minimal information is available on the relationship between WSS and plaque composition.

Advances in two-dimensional quantitative coronary angiographic assessment of bifurcation lesions: improved small lumen diameter detection and automatic reference vessel diameter derivation.

Aims: To validate a new two dimensional (2-D) bifurcation quantitative coronary angiography (QCA) software.

Methods And Results: In the latest edition of the Cardiovascular Angiography Analysis System (CAAS 5.9; Pie Medical Imaging, Maastricht, The Netherlands) video-densitometric information is dynamically integrated into the edge-detection algorithm of 11- and 6-segment models to reduce overestimation of small diameters.

Validity and variability in visual assessment of stenosis severity in phantom bifurcation lesions: a survey in experts during the fifth meeting of the European Bifurcation Club.

Objectives: To investigate the adequacy of visual estimate regarding the percent diameter stenosis (DS) in bifurcation lesions.

Background: Quantitative coronary angiography (QCA) is more accurate and precise compared to visual estimate in assessing stenosis severity in single-vessel lesions.

Methods: Thirty-six experts in the field of bifurcation PCI visually assessed the DS in cine images of five precision manufactured phantom bifurcation lesions, experts being blinded to the true values.

Detection and quantification of coronary atherosclerotic plaque by 64-slice multidetector CT: a systematic head-to-head comparison with intravascular ultrasound.

Objective: We evaluated the ability of 64-slice multidetector computed tomography (MDCT)-derived plaque parameters to detect and quantify coronary atherosclerosis, using intravascular ultrasound (IVUS) as the reference standard.

Methods: In 32 patients, IVUS and 64-MDCT was performed. The MDCT and IVUS datasets of 44 coronary arteries were co-registered using a newly developed fusion technique and quantitative parameters were derived from both imaging modalities.

High shear stress induces a strain increase in human coronary plaques over a 6-month period.

Aims: Atherosclerotic plaques develop in low shear stress regions. In the more advanced phase of the disease, plaques are exposed to altered shear stress levels, which could influence plaque composition. We investigated changes in plaque composition in human coronary arteries over a 6-month period and how these changes are related to shear stress.

Two-dimensional quantitative coronary angiographic models for bifurcation segmental analysis: in vitro validation of CAAS against precision manufactured plexiglas phantoms.

Background: Quantitative coronary angiography (QCA) analysis for bifurcation lesions needs to be standardized.

Objectives: In vitro validation of two models for bifurcation QCA segmental analysis.

Methods: In the latest edition of the Cardiovascular angiography analysis system (CAAS 5v8, Pie Medical Imaging, Maastricht, The Netherlands) a 6-segment model for two-dimensional coronary bifurcation analysis was implemented next to the currently available 11-segment model.

Novel bifurcation phantoms for validation of quantitative coronary angiography algorithms.

Background: Validation is lacking for two- and three-dimensional (2D and 3D) bifurcation quantitative coronary angiography (QCA) algorithms.

Methods: Six plexiglas phantoms were designed, each of them mimicking a coronary vessel with three successive bifurcations lesions, wherein at least one vessel segment had a percent diameter stenosis (DS) of ≥60%. The five most frequently occurring Medina classes (1,1,1), (1,1,0), (0,1,0), (0,1,1), and (1,0,0) were used in the design.

In vivo validation of CAAS QCA-3D coronary reconstruction using fusion of angiography and intravascular ultrasound (ANGUS).

Objectives: The CAAS QCA-3D system (Pie Medical Imaging BV, the Netherlands) was validated against 3D reconstructions based on fusion of angiography and intravascular ultrasound (ANGUS), allowing slice by slice validation of the lumen areas and 3D geometric values.

Background: Accurate online 3D reconstruction of human coronary arteries is of outmost importance during clinical practice in the catheterization laboratory. The CAAS QCA-3D system provides technology to 3D reconstruct human coronary arteries based on two or more angiographic images, but was not validated in realistic arteries before.

Strain distribution over plaques in human coronary arteries relates to shear stress.

Once plaques intrude into the lumen, the shear stress they are exposed to alters with hitherto unknown consequences for plaque composition. We investigated the relationship between shear stress and strain, a marker for plaque composition, in human coronary arteries. We imaged 31 plaques in coronary arteries with angiography and intravascular ultrasound.

Coronary plaque composition as assessed by greyscale intravascular ultrasound and radiofrequency spectral data analysis.

Objectives: (i) To explore the relation between greyscale intravascular ultrasound (IVUS) plaque qualitative classification and IVUS radiofrequency data (RFD) analysis tissue types; (ii) to evaluate if plaque composition as assessed by RFD analysis can be predicted by visual assessment of greyscale IVUS images.

Methods: In 120 IVUS-RFD cross-sections, a sector of the plaque with homogenous tissue composition (e.g.

A new imaging technique to study 3-D plaque and shear stress distribution in human coronary artery bifurcations in vivo.

Objective: Bifurcations of coronary arteries are predilection sites for atherosclerosis and expansive remodeling, the latter being associated with plaque vulnerability. Both are related to blood flow-induced shear stress (SS). We present a new approach to generate 3-D reconstructions of coronary artery bifurcations in vivo and investigate the relationship between SS, wall thickness (WT) and remodeling.

Virtual histology and remodelling index allow in vivo identification of allegedly high-risk coronary plaques in patients with acute coronary syndromes: a three vessel intravascular ultrasound radiofrequency data analysis.

Background: Virtual histology (VH) uses intravascular ultrasound (IVUS) radiofrequency spectral analysis to locally identify the morphology and composition of atherosclerotic plaques. We sought to explore in vivo the relation between IVUS-derived thin cap fibro-atheroma (IDTCFA) and remodelling index in patients with acute coronary syndromes using IVUS-VH.

Methods And Results: Twenty-one patients (63 vessels) were enrolled.

The role of shear stress in the generation of rupture-prone vulnerable plaques.

Blood-flow-induced shear stress acting on the arterial wall is of paramount importance in vascular biology. Endothelial cells sense shear stress and largely control its value in a feedback-control loop by adapting the arterial dimensions to blood flow. Nevertheless, to allow for variations in arterial geometry, such as bifurcations, shear stress control is modified at certain eccentrically located sites to let it remain at near-zero levels.

Geometry guided data averaging enables the interpretation of shear stress related plaque development in human coronary arteries.

The average low shear stress (SS) is known to determine predilection sites of atherosclerotic plaques. However, as plaques encroach into the lumen and thereby increase SS, interpretation of patient-specific data obtained at one moment in time regarding the influence of SS in the generation of atherosclerosis is not straightforward. This study aims to compare two methods of data analysis for the aid of data interpretation: (a) point-wise analysis of the raw data, (b) global analysis: to assess the history related natural SS distribution in coronary arteries by averaging the data in the axial vessel direction.

A biplane angiographic study on cardiac motion of coronary artery stents: options to minimize the target volume for high-precision external beam radiotherapy of coronary artery in-stent restenosis.

Purpose: High-precision external beam radiotherapy (EBRT) has been suggested as a potential alternative to endovascular brachytherapy for the treatment of coronary artery in-stent restenosis. The purpose of our study was to investigate and compare different options to define a smallest feasible target volume.

Methods And Materials: The cardiac motion of 17 coronary artery stents in 17 patients was studied by use of biplane conventional angiography, recorded during breath-hold.

Usefulness of shear stress pattern in predicting neointima distribution in sirolimus-eluting stents in coronary arteries.

The true 3-dimensional neointimal thickness distribution in sirolimus-eluting stents was investigated in relation to the shear stress distribution, which was obtained from computational fluid dynamics calculations. Small pits were observed between the stent struts in all patients, and a significant inverse relation between neointimal thickness and shear stress was found, indicating that deeper pits were present in the outside curve of the stented segments.