Eccentric Plaque Research Articles

3039Vulnerability of carotid atherosclerosis: relationship with plaque location, plaque eccentricity and vessel remodeling patterns. Insight from the the MAGNETIC observational study

Abstract Carotid atherosclerosis is a cause of brain ischemic events. Cardiovascular magnetic resonance (CMR) can assess plaque vulnerability. We investigated atherosclerosis vulnerability in relation to plaque location, eccentricity and vessel remodeling. Methods-Baseline CMR evaluations of the MAGNETIC observational study, were analyzed. We quantitated with MRI-Plaque View™, vessel lumen/wall and vulnerable plaque components of a 32-mm segment of common carotid artery (12 mm), bulb (8 mm) and internal carotid artery (12 mm). Lipid-rich necrotic core [LRNC], fibrous cap [CAP] and intraplaque hemorrhage [IPH] were expressed as percent of wall area. Results-A data-set of 8080 sections of adequate quality in 260 patients (198 male [76%], median age 71 years [65–76]), were analyzed. Patients were on therapy with antiplatelet, ACE-inhibitors/ARB and statins (196–229 out of 260 [75–88%]). We found significant differences in plaque composition according to longitudinal and circumferential location, eccentricity and vessel remodeling (table). At multivariate regression analysis, including classical RF and atherosclerotic burden, we found an independent association of: LRNC and IPH with longitudinal location, eccentricity and positive remodeling, and of CAP with eccentricity (p<0.001 for all). Lipid-rich necrotic core Fibrous cap Intraplaque hemorrhage Longitudinal distribution Common carotid artery 4% [1–10] p<0.001 6% [4–11] p<0.001 0% [0–3] p<0.001 Carotid bulb 7% [3–13] 9% [5–13] 1% [0–4] Internal carotid artery 3% [0–10] 7% [4–11] 0% [0–1] Circunferenzial location Antero-medial 4% [0–11] p<0.001 7% [4–12] p=0.07 0% [0–2] p<0.001 Antero-lateral 6% [1–12] 8% [5–12] 1% [0–4] Postero-lateral 5% [0–11] 7% [4–12] 0% [0–3] Postero-medial 5% [0–11] 7% [4–12] 0% [0–1] Plaque eccentricity Concentric 3% [0–9] p<0.001 7% [4–11] p<0.001 0% [0–2] p<0.001 Eccentric 9% [4–15] 9% [5–13] 1% [0–4] Remodelling pattern Negative 4% [0–10] p<0.001 7% [4–11] p<0.001 0% [0–2] p<0.001 Positive 7% [3–13] 8% [5–13] 1% [0–4] Plaque eccentricity was defined as eccentricity index (EI = [maximum wall thickness − minimum wall thickness]/maximum wall thickness) in the highest quartile. Positive remodeling was defined as remodeling index (= [vessel cross-sectional area − reference area]/cross-sectional area) in the highest quartile. Conclusions Carotid atherosclerotic plaque vulnerability seems to be independently associated with longitudinal location, plaque eccentricity and vessel positive remodeling. Acknowledgement/Funding Bayer AG, Leverkusen, Germany

P3596The role of MSCT and SPECT in patients with acute coronary syndromes and non-obstructive coronary artery disease

Abstract Background Approximately 1–14% of patients with ACS not have obstructive changes in the coronary arteries according to the data of invasive coronary angiography (ICA) is myocardial infarction (AMI) with non-obstructive coronary artery- MINOCA. MSCT has the ability to assess the lumen of the vessel, visualize the artery wall, the structure of the atherosclerotic plaque. SPECT is used to detect myocardial ischemia, determine the functional significance of atherosclerotic plaques, and evaluate regional tissue perfusion. There are no data on a research of a structurally functional condition of a coronary blood-groove by means of MSCT, SPECT.Aim. To study the role of MSCT and SPECT in patients with MINOCA, to compare MSCT with invasive coronarography. Material and methods The study is registered on ClinicalTrials.gov. Inclusion criteria are listed on the site. All patients underwent CT, SPECT, on the 6th day from the beginning of the index event. All MSCT and SPECT studies were performed on a 64-section combined single-photon-emission and X-ray computer tomograph GE Discovery NM/CT 570C. Endpoint: Frequency of occurrence of atherosclerosis, frequency of occurrence of unstable plaques according to MSCT, the magnitude of a transient defect in myocardial perfusion according to SPECT. Results The study included 14 patients with MINOCA, women predominate – 11 (78.6%), the average age was 61.1±14 years. The risk of GRACE was moderate in 8 (57%) pts. 12 (85.7%) pts were hospitalized within the first 6 hours of the onset of the disease.Thrombolytic therapy was performed in 3 (21.4%) pts, 2 of them were effective (14%). 57% of patients at admission were troponin-positive.According to the results of ICA, intact coronary arteries were detected in 9 (64.3%) pts, 5 (35%) had stenosis up to 50%. Coronary slow flow (TIMI 2) was determined in 11 (78.6%) pts, of which 8 (57%) pts have coronary slow flow and intact coronary arteries. Coronary spasm was in 1 (7.1%) patient. According to MSCT, the proportion of pts with intact coronary arteries decreased (9 (64.3%) → 5 (35.7%)) and the proportion with non-obstructive atherosclerosis increased (5 (35%) → 9 (64.3%)). All pts had a positive remodeling index, soft-tissue, predominantly calcified stenoses and eccentric plaques. The average Segment Involvement Score was 2.1 (0; 5), the Segment Stenosis Score was −2.4 (1; 3). 12 pts (85%) had transitory perfusion defects. The median SSS values were 7.5 (4; 13), SRS 4.7 (1.0; 9.0), SDS 4.7 (3.0; 8.0). Conclusion In 78% of pts had a slowing of the coronary blood flow and intact coronary arteries according to ICAG. However, according to MSCT, only 36% of the patients did not have plaques. MSCT allows to identify eccentric soft tissue atherosclerotic plaques that have a high risk of rupture/erosion, and, accordingly, the high risk of the development of AMI in this group. Using SPECT revealed a statistically significant transient perfusion defect.

P3644Plaque progression from normal vessel wall to fibroatheroma: lessons from over 5-year follow-up optical coherence tomography study

Abstract Background Progression of atherosclerosis is a non-uniform process characterized by coexistence of normal vessel wall (NVW) and advanced fibroatheroma within the same cross-section (Figure). Plaque progression from NVW to fibroatheroma usually takes years, that has never been investigated in human. Purpose To investigate the incidence and related factors associated with atherosclerotic progression from NVW to fibroatheroma using long-term serial optical coherence tomography (OCT) follow-up data over 5 years. Methods We enrolled 47 vessels in 30 patients who had undergone serial OCT imaging over 5 years (average: 6.8 years). Baseline and follow-up OCT images were matched for longitudinal and circumferential location and OCT cross-sections that had NVW >30 degrees were enrolled. NVW was defined as vessel wall having OCT-detectable three-layer structure with intimal thickening ≤300μm. Cross-sections were diagnosed as +Progression when NVW in the cross-section reduced by >30 degrees during >5-year follow-up. Results In the present study, atherogenic progression from NVW to fibroatheroma was observed only in 37.2% of the enrolled cross-sections. On the other hand, despite an average long-term follow-up period of 6.8 years, the extent of NVW was maintained in 62.8% of cross-sections. The incidence of microchannel in adjacent fibroatheroma within the same cross-section (23.6% vs. 13.1%, p=0.023), eccentric plaque distribution (21.7% vs. 11.4%, p=0.019), and concave shape (6.6% vs. 0%, p=0.001) at baseline was significantly higher in cross-sections with +Progression than those without Progression. Average intimal thickness of NVW (187.2±64.9μm vs. 170.7±68.6μm; p=0.048) at baseline was significantly thicker in cross-sections with +Progression than those without. Multivariate analysis demonstrated that the presence of microchannel, eccentric plaque distribution and thicker average intimal thickness of NVW at baseline were independently associated with plaque progression during the follow-up. Atheroma progression Conclusion The presence of microchannel in adjacent fibroatheroma, eccentric plaque distribution, and thicker intimal thickening of NVW were potentially associated with plaque progression from NVW to fibroatheroma.

78-Year-Old Woman With Intermittent Chest Pain and Palpitations

78-Year-Old Woman With Intermittent Chest Pain and Palpitations

Looking into the Future: Optical Coherence Tomography for the Assessment of Cardiac Allograft Vasculopathy

Introduction Current guidelines recommend coronary angiography with intravascular ultrasound (IVUS) as a screening and surveillance tool for the assessment of cardiac allograft vasculopathy (CAV). The role of optical coherence tomography (OCT) has not been thoroughly evaluated for patients with CAV. Case Description A 59 M with history of ICM with subsequent OHT in 2016 with evidence of an eccentric LAD plaque and CAV with IMT of 0.66 mm on IVUS being treated with Rosuvastatin and Sirolimus presented for second annual follow up angiogram. On coronary angiography all of his vessels appeared angiographically “pristine” without evidence of vasculopathy (Figure 1). OCT showed show evidence of extensive subintimal hyperplasia (0.45 mm at thickest area) with negative vessel remodeling, unappreciable on the coronary angiography (Figure 2). Conclusion IVUS has traditionally been used for the assessment of CAV. OCT has a much higher resolution (10microns) compared to IVUS (80microns) and provides exceptional tissue characterization similar to a light microscope. OCT should hence be considered for the routine evaluation and surveillance of CAV.

ACUTE CORONARY SYNDROME WITH NONOBSTRUCTIVE CORONARY ARTERIES: THE SEVERITY OF CORONARY ATHEROSCLEROSIS AND MYOCARDIAL PERFUSION DISORDERS (PILOT STUDY)

Aim. To study the structural and functional status of coronary blood flow in patients with acute coronary syndrome with nonobstructive coronary arteries using multispiral computed tomography (MSCT) and single photon emission tomography (SPECT) and to compare data of MSCT and invasive coronary angiography (ICA).Material and Methods. This study is a non-randomized, open-label, controlled clinical trial. The study is registered on ClinicalTrials.gov. The inclusion criteria are listed on the site. All patients underwent CT and SPECT.Results. The study included 14 patients with MINOCA; the group comprised predominantly women (n=11, 78.6%); the average age was 61.1±14 years. The risk according to GRACE (Global Registry of Acute Coronary Events) risk score was moderate in 8 patients (57%) and high in 5 patients (35.7%). 85.7% of patients were admitted to hospital within the first six hours from onset of diseases. Three patients (21.4%) received thrombolytic therapy and it was effective in two of them (14%). Risk factors included hypertension (64.2%), dyslipidemia (50%), and burdened history (71.4). According to the results of invasive coronary angiography, intact coronary arteries were detected in 9 patients (64.3%); 5 patients (35.7%) had stenosis up to 50%. Coronary slow-flow phenomenon (TIMI 2) was detected in 11 patients (78.6%) including 8 patients (57.1%) who had coronary slow-flow phenomenon and intact coronary arteries. Severe coronary spasm was registered in 1 patient (7.1%) in the group with ST segment elevation acute coronary syndrome (STE ACS). According to MSCT data, the proportion of patients with intact coronary arteries decreased from 7 (50%) to 5 patients (35.7%) whereas the proportion of patients with nonstenosing atherosclerosis increased from 7 (50%) to 9 patients (64.3%). Twenty six atherosclerotic plaques were detected including eccentric (76%), circular (11.5%), and semi-circular plaques (11.5%). In regard to morphological structure, the atherosclerotic plaques were calcified (59.5%), mostly calcified (7.7%), and soft (29%). Normal myocardial perfusion (Summed Stress Score (SSS) and Summed Rest Score (SRS) <4) was detected in two patients (14.3%); 12 patients (85%) had transitory perfusion defects. The median score values were 7.5 (4; 13) for SSS, 4.7 (1.0; 9.0) for SRS, and 4.7 (3.0; 8.0) for SDS.Conclusion.The introduction of MCTA and SPECT into the algorithm of the examination of patients with acute myocardial infarction and non-obstructive atherosclerosis of the coronary arteries was safe when additionally used during index hospitalization. These approaches provided new information about the structure and function of the coronary arteries. These data provide rationale for further study using a larger group of patients to determine a prognostic significance of detecting the atherosclerotic plaques with the signs of instability in this patient category.

Vulnerability analysis on the interaction between Asymmetric stent and arterial layer.

The utilization of Asymmetric stent for recovering atherosclerotic diseases, particularly non-symmetric obstruction, is a quite challenging breakthrough treatment. In terms of eccentric plaque, the non-uniform stiffness of arterial layer causes the increasingly complex issues of vulnerability. This study investigated the vulnerability of the interaction between the Asymmetric stent and the surrounding arterial layer using structural transient dynamic analysis in ANSYS. Four combinations of stent deployment, i.e. the Sinusoidal stent expanded by the offset balloon, the Sinusoidal stent expanded by the ordinary cylindrical balloon, the Asymmetric stent expanded by the offset balloon, and the Asymmetric stent expanded by the ordinary cylindrical balloon, are generated for this comparative study. Multilayer material properties from recent in vitro experiments are adopted for the surrounding arterial layer, such as a fibrous cap, lipid core, diseased-healthy intima, and diseased-healthy media. In order to address plaque vulnerability, the Cauchy stresses and Hencky strains are used for stress measure because of convenience in comparison with the uniaxial/biaxial tension test data. The location-specific threshold value from the diseased human carotid artery is adopted for rupture criteria. The simulation indicated that as regards the eccentric plaque, the plaque vulnerability is caused by the plaque shape and components rather than caused by the geometrical structure of the stent or balloon expansion method. Nevertheless, the non-symmetric inflation of balloon, which leads against the plaque, contributed to an increase in the vulnerability of fibrous cap of fibroatheroma plaque.

Combination of Plaque Characteristics, Pial Collaterals, and Hypertension Contributes to Misery Perfusion in Patients With Symptomatic Middle Cerebral Artery Stenosis.

Atherosclerotic plaque in the middle cerebral artery (MCA) is linked to ischemic stroke events, but the relationship between plaque characteristics and cerebral perfusion is unclear. To investigate MCA plaque characteristics between intracranial atherosclerotic patients with and without hypoperfusion area, and to identify the variables affecting hypoperfusion volume. Retrospective. Seventy-one patients with MCA stenosis (>50%), and all with ischemic onset in recent 2 weeks. 3.0T MRI / diffusion-weighted imaging (DWI), time-of-flight magnetic resonance angiography (TOF-MRA), inversion-recovery prepared sampling perfection with application-optimized contrast using different flip angle evolutions (IR-SPACE), dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI). Plaque characteristics including eccentric index (EI), eccentricity, plaque length, and enhancement on MCA were measured on IR-SPACE. Pial collaterals (PCs) were evaluated on axial TOF-MRA source images. Time-to-maximum (Tmax) maps with a threshold more than 6 seconds were assessed by rapid processing of perfusion and diffusion (RAPID) software. Two independent-samples t-tests, Mann-Whitney U-test, chi-square test, Z test, univariate and multivariate logistic analysis, and receiver operating characteristic (ROC) curve were used. Patients with hypoperfusion had fewer eccentric plaque, lower EI, longer plaque length, and poor PCs compared with those without (P = 0.002, 0.016, 0.003, and 0.001). Eccentricity, plaque length, PCs, and hypertension were the factors independently associated with the occurrence of hypoperfusion after adjustment for risk factors of cerebrovascular disease (P = 0.014, 0.017, 0.035, and 0.018). The area under the curve (AUC) (95% confidence interval) was 0.865 (0.763-0.934) for a combination of the above four variables, which was significantly higher than any variable alone (P < 0.001, 0.016, < 0.001, and < 0.001). Patients with lower EI, concentric morphology, and grade 2 enhancement trended to have larger hypoperfusion volume (P = 0.028, 0.037, and 0.009). Plaque eccentricity, plaque length, PCs, and hypertension showed an association with the occurrence of hypoperfusion. 4 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:195-204.

Serial Coronary Plaque Assessment Using Computed Tomography Coronary Angiography

Serial Coronary Plaque Assessment Using Computed Tomography Coronary Angiography

Coronary Plaque Geometry and Thoracic Fat Distribution in Patients with Acute Chest Pain – a CT Angiography Study

Abstract The aim of our study was to investigate the correlation between volumes of thoracic fat distributed in different compartments and the geometry of vulnerable coronary plaques assessed by coronary computed tomography angiography (CCTA), in patients with acute chest pain. Methods: This was a non-randomized, observational, single-center study, including 50 patients who presented in the emergency department with acute chest pain who underwent 128-slice single-source CCTA. Plaque geometry was evaluated in transversal and longitudinal planes, and the assessment of adipose tissue was performed using the Syngo.via Frontier (Siemens AG, Healthcare Sector, Forchheim, Germany) research platform. Results: Eccentric plaques presented a significantly higher incidence of spotty calcification (40% vs. 22%, p = 0.018), whereas positive remodeling, volume of low attenuation plaque, and incidence of napkin-ring sign were not significantly different between the study groups or in ascending versus descending plaques. The volume of pericoronary fat around the plaque was significantly larger near eccentric lesions (707.68 ± 454.08 mm3 vs. 483.25 ± 306.98 mm3, p = 0.046) and descendent plaques (778.26 ± 479.37 mm3 vs. 473.60 ± 285.27 mm3, p = 0.016). Compared to ascending lesions, descendent ones presented a significantly larger volume of thoracic fat (1,599.25 ± 589.12 mL vs. 1,240.71 ± 291.50 mL), while there was no significant correlation between thoracic fat and cross-sectional eccentricity. Conclusions: The phenotype of plaque distribution and geometry seems to be associated with a higher vulnerability of coronary lesions and may be influenced by the local accumulation of inflammatory mediators released by the pericoronary epicardial adipose tissue.

Quantitative score of the vessel morphology in middle cerebral artery atherosclerosis

BackgroundWe aimed to quantitatively assess the vessel morphology of middle cerebral artery (MCA) atherosclerosis and explore its value in discriminating plaque types. MethodsPatients were selected from a high-resolution magnetic resonance imaging (HRMRI) study from January 2007 to December 2015. One hundred and three patients with acute cerebral infarcts due to MCA stenosis (>50%) and eighty-nine patients with asymptomatic MCA stenosis (>50%) were included. Quantitative measurements of MCA morphology, including lumen area, outer-wall and wall area at stenotic site and reference site, stenotic degree, plaque length, remodeling index and plaque eccentricity, were performed on HRMRI with observers blinded to clinical presentations. Firth's penalized logistic regression analysis was used to construct a symptomatic plaque score (SPS) model. Then, the HRMRI data of 39 patients prospectively enrolled from January 2016 to January 2017 were used to validate the SPS model. ResultsThe HRMRI data of 103 patients with symptomatic MCA stenosis and 89 patients with asymptomatic MCA stenosis in the construction cohort were analyzed. Four main factors were found to be associated with symptomatic plaques: stenotic lumen area ≥ 2.28 mm2, stenotic wall area ≥ 8.88 mm2, plaque length and presence of an eccentric plaque. Summation of each logistic regression coefficient multiplying the corresponding score produced the SPS with an area under curve (AUC) of 0.890 on receiver operating characteristics analysis. Validation of the score of 39 plaques (19 symptomatic and 20 asymptomatic) revealed an AUC of 0.862, confirming the continued diagnostic ability. When the data were pooled in all 235 plaques, the optimal cutoff score of discriminating symptomatic and asymptomatic plaques was 2.79 (SPS ≥ 2.79 indicating a symptomatic plaque) with AUC = 0.886, sensitivity 81.1% and specificity 80.5%. ConclusionsThe quantitative analysis of MCA morphology can independently and accurately discriminate plaque types, suggesting its close association with the underlying pathophysiology. Further prospective studies are required to verify whether the SPS model is clinically valuable in monitoring plaque progression and assessing the vulnerability.

Invited commentary

In laminar flow situations, shear occurs in the zone between the blood vessel wall (velocity = zero) and the central column of flow. In vitro measurement of shear, sometimes difficult, has been achieved with laser Doppler sensors and with magnetic resonance techniques.1Yap C.H. Saikrishnan N. Tamilselvan G. Yoganathan A.P. Experimental technique of measuring dynamic fluid shear stress on the aortic surface of the aortic valve leaflet.J Biomech Eng. 2011; 133: 061007Crossref PubMed Scopus (27) Google Scholar, 2Campagnolo L. Nikolić M. Perchoux J. Lim Y.L. Bertling K. Loubiere K. et al.Flow profile measurement in microchannel using the optical feedback interferometry sensing technique.Microfluidics Nanofluidics. 2013; 14: 113-119Crossref Scopus (54) Google Scholar Casa et al diagrammed the cross section of flow velocity as parabolic for laminar flow and showed how platelets and blood clotting factors can be activated in the shear zone, the region where the velocity curve becomes asymptotic with the wall (Casa Fig 1). The thickness of this zone is related to many parameters, including viscosity. Shear forces are not uniform in the proximal internal carotid artery: under physiologic conditions, the zone of abnormal shear can vary longitudinally as well as along the circumference, as measurements with magnetic resonance techniques have demonstrated.3Markl M. Wegent F. Zech T. Bauer S. Strecker C. Schumacher M. et al.In vivo wall shear stress distribution in the carotid artery: effect of bifurcation geometry, internal carotid artery stenosis, and recanalization therapy.Circ Cardiovasc Imaging. 2010; 3: 647-655Crossref PubMed Scopus (160) Google Scholar The biologic behavior of artery walls in zones of severe stenosis is more difficult to model. Not only is there the problem of turbulence, but measurement accuracy is difficult because of physical limitations of instrumentation. A normal internal carotid artery diameter ranges from 6 to 8 mm, and a significantly stenotic segment is at or less than 1 mm. The axial gate size used to measure carotid flow velocity by duplex ultrasound is typically 1 to 3 mm. The axial resolution for this measurement is on the order of magnitude 0.1 to 0.2 mm, depending on the frequency selected, typically 9 to 12 MHz. Axial resolution is inversely proportional to frequency.4Kremkau F.W. Sonography principles and instruments.9th edition. Elsevier, St. Louis, MO2016: 66Google Scholar Because the formula for shear stress includes 1/(D3), there is potential for any value to have an inherent error between 30% and 70% based on the physics of ultrasound probes, irrespective of operator-related variability. Velocity measurements in a duplex ultrasound scan are sensitive to the beam angle, which is also operator dependent. If shear is to be used as a parameter for risk, it is therefore necessary that the measurement is conducted at the highest probe frequency and is not in an area of severely eccentric plaque, which may distort the measurements. For any vascular laboratory, the overall reproducibility of velocity measurements is not generally ascertained. Understanding that this is the case, reporting standards therefore mandate ranges, not use of precise velocities. Shear stress criteria may need to be formulated in a similar manner. Shear stress is proportional to blood viscosity. For the purposes of clarity, Casa et al did not factor variability of viscosity in their analysis, but it is well established that blood viscosity can vary significantly in any individual over time.5Wells Jr., R.E. Merrill E.W. The variability of blood viscosity.Am J Med. 1961; 31: 505-509Abstract Full Text PDF PubMed Scopus (26) Google Scholar Some literature indicates that viscosity is not really important in terms of carotid-related stroke risk,6Parkhurst K.L. Lin H.F. Devan A.E. Barnes J.N. Tarumi T. Tanaka H. Contribution of blood viscosity in the assessment of flow-mediated dilation and arterial stiffness.Vasc Med. 2012; 17: 231-234Crossref PubMed Scopus (21) Google Scholar but this should be validated in the context of the present study. Therefore, before translating from Casa to clinical utility, as proposed in this paper, it will be necessary for some significant research to occur. In particular, standards for precise vascular laboratory measurement will need to be redefined. The opinions or views expressed in this commentary are those of the author and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery. Shear rate is a better marker of symptomatic ischemic cerebrovascular events than velocity or diameter in severe carotid artery stenosisJournal of Vascular SurgeryVol. 69Issue 2PreviewThis study was designed to test the hypothesis that the high shear rate of flow in the area of carotid stenosis is associated with the incidence of ischemic symptoms in patients with a high degree of carotid stenosis. Full-Text PDF Open Archive

A New RF Heating Strategy for Thermal Treatment of Atherosclerosis.

Restenosis remains a challenge for the treatment of atherosclerosis due to the damage of the endothelial layer and induced proliferation of the smooth muscle cell. A new RF heating strategy was proposed to selectively ablate the atherosclerosis plaque, and to thermally inhibit the proliferation of smooth muscle cells, while keeping the endothelial cells intact. To achieve the goal, an internal cooling agent and distributed electrodes have been integrated in the new designed balloon catheter to focus the shape conformal energy onto the plaque shape. A three-dimensional (3-D) model with experimentally fitted parameters has been established to demonstrate the heating ability of the design and evaluate the microelectrodes configurations for different plaque geometries. The 3-D shape of the lesions resulting from different electrodes settings is obtained. It is found that by individual control of the micro-electrodes, special shapes of the lesions can be formed, which can match the eccentric crescent plaques. Besides, through changing of the polarity of the electrodes, separate lesions can be reached. This suggests the possibility for treatment of disconnected plaques in situ. By the control of RF heating and convection coefficient of the internal cooling agent, a targeted heating region away from the inner surface of the blood vessel can be realized. This study has illustrated the possibility of achieving a precision thermal treatment of atherosclerosis in favor of inhibiting further restenosis.

Using IVUS to improve treatment of complex lesions in the femoropopliteal arteries

Despite rapid advances in in peripheral endovascular therapy over the last 15 years, the rate of restenosis and revascularization in the femoropopliteal arteries remains high. This is particularly the case for more complex lesions, such as longer lesions, those with severe calcification and chronic total occlusions (CTO). The recognised limitations of angiography, particularly the planar and luminal nature of the imaging, result in incomplete assessment of lesion characteristics which may well contribute to problems with achieving satisfactory outcomes. Intravascular ultrasound (IVUS) is a fundamentally different mode of imaging to angiography and is able to produce high quality imaging of the entire artery rather than just the lumen. IVUS provides a range of imaging parameters, many of which are unique to this form of imaging and are unobtainable with angiography. IVUS can therefore assist with a more complete characterisation of the artery and lesion beyond the luminal silhouette and diameters provided by angiography. In this presentation, the role of intravascular imaging (IVUS) in treating complex femoropopliteal lesions will be reviewed, drawing on more than five years’ experience with this technology. The value of IVUS both before and after treatment will be discussed. This will include how pre-treatment IVUS imaging can assist selection of the most appropriate treatment methods by providing accurate assessment of vessel dimensions, length of the diseased segment, severity of calcification, presence of negative remodelling and the degree of plaque eccentricity. This information can inform the choice of treatment technology as well as optimising device size and the length of treatment. IVUS can also provide unique information after initial treatment. This includes accurate measurement of minimum lumen size post angioplasty and stenting, the presence of dissection and the effects of atherectomy, including assessment of the effectiveness of plaque removal and identification of vessel wall damage. IVUS imaging is simple, quick and safe to use during endovascular interventions and can provide unique information that can supplement standard angiographic imaging and help optimise treatments.

Reproducibility of quantitative coronary computed tomography angiography in asymptomatic individuals and patients with acute chest pain.

PurposeQuantitative computed tomography (QCT) provides important prognostic information of coronary atherosclerosis. We investigated intraobserver and interobserver QCT reproducibility in asymptomatic individuals, patients with acute chest pain without acute coronary syndrome (ACS), and patients with acute chest pain and ACS.MethodsFifty patients from each cohort, scanned between 01/02/2010-14/11/2013 and matched according to age and gender, were retrospectively assessed for inclusion. Patients with no coronary artery disease, previous coronary artery bypass graft surgery, and poor image quality were excluded. Coronary atherosclerosis was measured semi-automatically by 2 readers. Reproducibility of minimal lumen area (MLA), minimal lumen diameter (MLD), area stenosis, diameter stenosis, vessel remodeling, plaque eccentricity, plaque burden, and plaque volumes was assessed using concordance correlation coefficient (CCC), Bland-Altman, coefficient of variation, and Cohen’s kappa.ResultsA total of 84 patients (63 matched) were included. Intraobserver and interobserver reproducibility estimates were acceptable for MLA (CCC = 0.94 and CCC = 0.91, respectively), MLD (CCC = 0.92 and CCC = 0.86, respectively), plaque burden (CCC = 0.86 and CCC = 0.80, respectively), and plaque volume (CCC = 0.97 and CCC = 0.95, respectively). QCT detected area and diameter stenosis ≥50%, positive remodeling, and eccentric plaque with moderate-good intraobserver and interobserver reproducibility (kappa: 0.64–0.66, 0.69–0.76, 0.46–0.48, and 0.41–0.62, respectively). Reproducibility of plaque composition decreased with decreasing plaque density (intraobserver and interobserver CCC for dense calcium (>0.99; 0.98), fibrotic (0.96; 0.93), fibro-fatty (0.95; 0.91), and necrotic core tissue (0.89; 0.84). Reproducibility generally decreased with worsening clinical risk profile.ConclusionsSemi-automated QCT of coronary plaque morphology is reproducible, albeit with some decline in reproducibility with worsening patient risk profile.

Endovascular treatment for the common femoral artery: is there a challenger to open surgery?

Common femoral artery (CFA) atherosclerotic lesions currently remain one of the last limitations for adoption of endovascular repair as the first-line treatment. The bulky, eccentric, heavily calcified character of the CFA plaques, frequent involvement of the femoral bifurcation, easy surgical accessibility and last but not least, favorable long-term outcomes still make CFA disease treatment part of the surgical domain. In the last 5 years, improvement of the endovascular equipment and technical skills of the operators have led to an increase in percutaneous CFA procedures. Especially the vascular mimetic implant Supera Peripheral Stent system (Abbott Vascular), with its extreme crush resistance (if correctly implanted), seems to be an ideal tool to deal with eccentric calcified plaques, crush risk and maintaining access possibilities. The multicentric, prospective, single arm VMI-CFA Trial evaluates the outcome of treatment of symptomatic (Rutherford 2-4) CFA stenotic or occlusive lesions with the Supera Peripheral Stent System. A 6-month cumulative primary patency rate of 100% is noticed, up to 210 days. The cumulative freedom from TLR rate is 100%. Four patients died, not procedure or device related. From a clinical point of view, a tremendous switch from Rutherford 2-4 towards Rutherford 0-1 happened. No procedure nor device related adverse events are noticed. These short-term data confirm the safety and feasibility of an endovascular approach with the Supera stent to the "no-stent zone" CFA. Of course 12- and 24-month data are essential to bring more clarification in this interesting field.

The effect of plaque eccentricity on blood hemodynamics and drug release in a stented artery

Atherosclerosis in the coronary arteries is one of the leading causes of death in the world. Percutaneous coronary interventions (PCI) associated with the implantation of drug eluting stents (DES) is one of the most common forms of revascularization in patients with atherosclerotic coronary artery disease. The use of DES is considered as an effective tool to reduce restenosis after PCI. However despite all the progress made in DES procedures, the rate of restenosis remains relatively high. Mathematical modeling and numerical simulation are believed to play an essential role in identifying zones with a higher risk of in-stent restenosis. In this work the local delivery of a therapeutic agent, from a stent implanted in a coronary artery, is mathematically modeled and numerically simulated. The mathematical model includes the diffusion of the dissolved drug in the biodegradable polymeric coating of the stent, the diffusion and convection of the drug with reversible binding in the viscoelastic arterial wall with plaques of different morphology and the local hemodynamics. The study is an attempt to detect zones with a higher risk of in-stent restenosis and their relation to plaque eccentricity. The location of zones with highest risk of thrombosis and plaque rupture is also addressed. The results are in agreement with claims presented in clinical papers.

Influences of plaque eccentricity and composition on the stent-plaque-artery interaction during stent implantation.

This work aims to investigate the effects of plaque eccentricity and composition on the stent performance and stress distributions of plaque and artery during stenting by the finite element method. Three-dimensional stent-plaque-artery models for plaques with five different eccentricities and four different compositions were simulated, and the influences on stent recoil, stent plastic strain, stent foreshortening, stress distributions of artery and plaque, and lumen gain were studied. The results show that greater plaque eccentricity leads to greater stent recoil, stent plastic strain, stent foreshortening, maximum von Mises stresses of artery and plaque, and volume percentage of plaque in higher stress. Plaque composition exerts a great effect on all indices except the maximum von Mises stress of artery. The lipid pool declines stent recoil, but increases the maximum plastic strain of stent due to its softness, while the fibrous cap reduces stent foreshortening. Because of the existence of fibrous cap/calcified zones, plaque with greater eccentricity and higher mixture of components is more vulnerable during stenting process; thus, a larger expanding pressure should be carefully applied and a slightly longer stent should be used. The present study suggests that the real plaque geometry and composition in numerical simulations should be considered as an integral part of stent design and development, also is useful in enhancing our understanding of the mechanics of stent-plaque-artery interaction during stent implantation to improve the stent's long-term clinical outcome.

Left ventricular hypertrophy diagnosed after a stroke: a case report

BackgroundStroke is a recognized clinical course of hypertrophic cardiomyopathy. This interesting case showed notable difference on the electrocardiogram of a patient 4 months prior to suffering a stroke and 10 days after suffering a stroke. The pre-stroke electrocardiogram showed atrial fibrillation with a narrow QRS complex, while the post-stroke electrocardiogram showed marked left ventricular hypertrophy. Left ventricular hypertrophy was diagnosed using the Sokolow-Lyon indices. The development of left ventricular hypertrophy a few days after suffering a stroke has not previously been reported.Case presentationAn 83-year-old white British woman with a background history of permanent atrial fibrillation, hypertension, and previous stroke attended the emergency department with a 2-day history of exertional dyspnea, and chest tightness. On examination, she had bibasal crepitations with a systolic murmur loudest at the apex.In-patient investigations include an electrocardiogram, blood tests, chest X-ray, contrast echocardiogram, coronary angiogram, and cardiovascular magnetic resonance imaging. An electrocardiogram showed atrial fibrillation, with inferolateral T wave inversion, and left ventricular hypertrophy. A chest X-ray showed features consistent with pulmonary edema. A contrast echocardiogram showed marked hypertrophy of the mid to apical left ventricle, appearance consistent with apical hypertrophic cardiomyopathy. Coronary angiography showed eccentric shelf-type plaque with non-flow-limiting stenosis in the left coronary artery main stem. Cardiovascular magnetic resonance imaging reported findings highly suggestive of apical hypertrophic cardiomyopathy. Our patient was treated and discharged on rivaroxaban, bisoprolol, and atorvastatin with a follow-up in the cardiomyopathy outpatient clinic.ConclusionsElectrocardiogram diagnosis of left ventricular hypertrophy led to the diagnosis of apical hypertrophic cardiomyopathy in this patient. Left ventricular hypertrophy was only evident a few days after our patient suffered a stroke. The underlying mechanisms responsible for this remain unclear. Furthermore, differential diagnosis of hypertrophic cardiomyopathy should be considered in people with electrocardiogram criteria for left ventricular hypertrophy. Cardiovascular magnetic resonance imaging is an important diagnostic tool in identifying causes of left ventricular hypertrophy. Family screening should be recommended in patients with new diagnosis of hypertrophic cardiomyopathy.

Development of asymmetric stent for treatment of eccentric plaque.

The selection of stent and balloon type is decisive in the stenting process. In the treatment of an eccentric plaque obstruction, a symmetric expansion from stent dilatation generates nonuniform stress distribution, which may aggravate fibrous cap prone to rupture. This paper developed a new stent design to treat eccentric plaque using structural transient dynamic analysis in ANSYS. A non-symmetric structural geometry of stent is generated to obtain reasonable stress distribution safe for the arterial layer surrounding the stent. To derive the novel structural geometry, a Sinusoidal stent type is modified by varying struts length and width, adding bridges, and varying curvature width of struts. An end ring of stent struts was also modified to eliminate dogboning phenomenon and to reduce the Ectropion angle. Two balloon types were used to deploy the stent, an ordinary cylindrical and offset balloon. Positive modification results were used to construct the final non-symmetric stent design, called an Asymmetric stent. Analyses of the deformation characteristics, changes in surface roughness and induced stresses within intact arterial layer were subsequently examined. Interaction between the stent and vessel wall was implemented by means of changes in surface roughness and stress distribution analyses. The Palmaz and the Sinusoidal stent were used for a comparative study. This study indicated that the Asymmetric stent types reduced the central radial recoiling and the dogboning phenomenon. In terms of changes in surface roughness and induced stresses, the Asymmetric stent has a comparable effect with that of the Sinusoidal stent. In addition, it could enhance the distribution of surface roughening as expanded by an offset balloon.