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Acute cerebral ischemic events and thrombosis are associated with the rupture/erosion of carotid atherosclerotic plaques. The aim of the present study was to determine the impact of calcification deposition on the wall shear stress (WSS) and stresses within the plaques using 3D fluid-structure interaction (FSI) models. Six patients with calcified carotid atherosclerosis underwent multisequence magnetic resonance imaging (MRI) and were divided into three groups according to the calcification volume. To evaluate the role of the calcification deposition on the stresses, the calcification content was replaced by lipids and arterial tissue, respectively. By comparing the results from the simulation with calcification, and when changing it to lipids there was a significant increment in the stresses at the fibrous cap (p = 0.004). Instead, by changing it to arterial tissue, there was no significant difference (p = 0.07). The calcification shapes that presented the highest stresses were thin concave arc-shaped (AS1) and thin convex arc-shaped (AS3), with mean stress values of 107 ± 54.2 and 99.6 ± 23.4 kPa, respectively. It was also observed that, the calcification shape has more influence on the level of stress than its distance to the lumen. Higher WSS values were associated with the presence of calcification. Calcification shape plays an important role in producing high stresses in the plaque. This work further clarifies the impact of calcification on plaque vulnerability.

Background: Carotid atherosclerosis is one of the main underlying inducements of stroke, which is a leading cause of disability. The morphological feature and biomechanical environment have been found to play important roles in atherosclerotic plaque progression. However, the biomechanics in each patient's blood vessel is complicated and unique., Method: To analyse the biomechanical risk of the patient-specific carotid stenosis, this study used the fluid-structure interaction (FSI) computational biomechanical model. This model coupled both structural and hemodynamic analysis. Two patients with carotid stenosis planned for carotid endarterectomy were included in this study. The 3D models of carotid bifurcation were reconstructed using our in-house-developed protocol based on multisequence magnetic resonance imaging (MRI) data. Patient-specific flow and pressure waveforms were used in the computational analysis. Multiple biomechanical risk factors including structural and hemodynamic stresses were employed in post-processing to assess the plaque vulnerability., Results: Significant difference in morphological and biomechanical conditions between 2 patients was observed. Patient I had a large lipid core and serve stenosis at carotid bulb. The stenosis changed the cross-sectional shape of the lumen. The blood flow pattern changed consequently and led to a complex biomechanical environment. The FSI results suggested a potential plaque progression may lead to a high-risk plaque, if no proper treatment was performed. The patient II had significant tandem stenosis at both common and internal carotid artery (CCA and ICA). From the results of biomechanical factors, both stenoses had a high potential of plaque progression. Especially for the plaque at ICA branch, the current 2 small plaques might further enlarge and merge as a large vulnerable plaque. The risk of plaque rupture would also increase., Conclusions: Computational biomechanical analysis is a useful tool to provide the biomechanical risk factors to help clinicians assess and predict the patient-specific plaque vulnerability. The FSI computational model coupling the structural and hemodynamic computational analysis, better replicates the in vivo biomechanical condition, which can provide multiple structural and flow-based risk factors to assess plaque vulnerability., (© 2021 S. Karger AG, Basel.)

Background and Purpose: The hemodynamic environment of an atherosclerotic plaque varies along the longitudinal direction. Investigating the changes in plaque morphology and its biomechanical environment along the longitudinal direction and their correlations will enhance our understanding of plaque progression and arterial remodeling., Methods: Six male patients with carotid stenosis >70% were recruited. Multisequence high-resolution MRI was performed at the carotid bifurcation. Carotid endarterectomy was performed following MRI, and the plaque tissue was collected for histological and mechanical testing. Patient-specific biomechanical modeling and simulations were conducted to calculate the mechanical stresses (wall shear stress [WSS] and von Mises stress [VMS]). Changes in plaque cross-sectional morphology, WSS, and VMS as well as their correlations were evaluated., Results: Positive correlations were found between % stenosis and % inflammation (MA) (p = 0.019), % lipid area and % MA (p = 0.026), and % calcification area and VMS (p = 0.007). Negative correlations were found between VMS and % stenosis (p = 0.028) and VMS and average WSS (p = 0.034). Moreover, the peak stresses and neovessels were found to be in the shoulder regions. High-stress concentrations were found in the interface regions of the calcification and surrounding tissue, thereby increasing plaque vulnerability., Conclusions: Correlations between the morphology and stresses suggest that arterial remodeling is a dynamic interaction between mechanical environment and plaque progression resulting in plaque heterogeneity. Our finding indicates that plaque heterogeneity is associated with plaque progression and can be combined with mechanical stresses for identifying high-risk plaques., (© 2021 S. Karger AG, Basel.)

The initiation and progression of atherosclerosis, which is the main cause of cardiovascular diseases, correlate with local haemodynamic factors such as wall shear stress (WSS). Numerical simulations such as computational fluid dynamics (CFD) based on medical imaging have been employed to analyse blood flow in different arteries with and without luminal stenosis. Patient-specific CFD models, however, have assumptions on blood rheology. The differences in the calculated haemodynamic factors between different rheological models have not been fully evaluated. In this study, carotid magnetic resonance imaging (MRI) was performed on six patients with different degrees of carotid stenosis and two healthy volunteers. Using the 3D reconstructed carotid geometries and the patient-specific boundary conditions, CFD simulations were performed by applying a Newtonian and four non-Newtonian models (Carreau, Cross, Quemada and Power-law). WSS descriptors and pressure gradient were analysed and compared between the models. The differences in the maximum and the average oscillatory shear index between the Newtonian and the non-Newtonian models were lower than 12.7% and 12%, respectively. The differences in pressure gradient were also within 15%. The differences in the mean time-averaged WSS (TAWSS) between the Newtonian and Cross, Carreau and Power-law models were lower than 6%. In contrast, a higher difference (26%) was found in Quemada. For the low TAWSS, the differences from the Newtonian to the non-Newtonian models were much larger, in the range of 0.4-31% for Carreau, 3-22% for Cross, 5-51% for Quemada and 10-41% for Power-law. The study suggests that the assumption of a Newtonian model is reasonable when the overall flow pattern or the mean values of the WSS descriptors are investigated. However, the non-Newtonian model is necessary when the low TAWSS region is the focus, especially for arteries with severe stenosis.

Background: Primary mycotic aneurysms and prosthetic graft infections are traditionally managed by resection of infected vascular tissue and revascularisation with an extra-anatomical bypass. Long-term patency for this method has been reported to be poor with associated high reinfection and limb amputation rates. The aim of this study was to analyse the outcomes of those patients in our department between 2010 and 2018 whom had revascularisation with in-situ arterial reconstruction using cryopreserved allograft as a conduit., Methods: The data were retrospectively reviewed and 13 patients were identified. There were five patients with primary mycotic aneurysms and eight patients with prosthetic graft infections, three of which were complicated by aortoenteric fistulae (AEF)., Results: There were three peri-operative mortalities (23%) with all three mortalities related to graft re-infection and post-implantation haemorrhage; two of these from uncontrolled bile leaks related to the original AEF with persistent graft contamination. The 10 surviving patients were followed up for a mean duration of 15.8 months with an overall primary graft patency of 89% and no incidence of graft re-infection or aneurysmal degeneration., Conclusion: Patients that survived the peri-operative period demonstrated acceptable medium-term allograft durability, with the most favourable outcomes observed in those patients who had arterial infections uncomplicated by AEF. The main barrier to more wide-spread use in our state remains inadequate supply of banked cryopreserved tissue., (© 2020 Royal Australasian College of Surgeons.)

Cardiac myxomas are the most common benign cardiac tumors in adults that can present with peripheral embolization. Complete detachments of myxomas are rare and tend to cause aortoiliac embolism. We report a case of a middle-aged woman with bilateral popliteal artery and segmental renal artery embolisms secondary to a completely detached cardiac myxoma. This case highlights cardiac myxomas as an important cause of acute limb ischemia and that it is not excluded by a normal echocardiogram result., (Copyright © 2019 Society for Vascular Surgery. All rights reserved.)

Atherosclerotic plaque rupture is a catastrophic event that contributes to mortality and long-term disability. A better understanding of the plaque mechanical behavior is essential for the identification of vulnerable plaques pre-rupture. Plaque is subjected to a natural dynamic mechanical environment under hemodynamic loading. Therefore, it is important to understand the mechanical response of plaque tissue under cyclic loading conditions. Moreover, experimental data of such mechanical properties are fundamental for more clinically relevant biomechanical modeling and numerical simulations for risk stratification. This study aims to experimentally and numerically characterize the stress-relaxation and cyclic mechanical behavior of carotid plaque tissue. Instron microtester equipped with a custom-developed setup was used for the experiments. Carotid plaque samples excised at endarterectomy were subjected to uniaxial tensile, stress-relaxation, and cyclic loading protocols. Thirty percent of the underlying load level obtained from the uniaxial tensile test results was used to determine the change in mechanical properties of the tissue over time under a controlled testing environment (Control tests). The stress-relaxation test data was used to calibrate the hyperelastic (neo-Hookean, Ogden, Yeoh) and linear viscoelastic (Prony series) material parameters. The normalized relaxation force increased initially and slowly stabilized toward the end of relaxation phase, highlighting the viscoelastic behavior. During the cyclic tests, there was a decrease in the peak force as a function of the cycle number indicating mechanical distension due to repeated loading that varied with different frequencies. The material also accumulated residual deformation, which increased with the cycle number. This trend showed softening behavior of the samples. The results of this preliminary study provide an enhanced understanding of in vivo stress-relaxation and cyclic behavior of the human atherosclerotic plaque tissue., (Copyright © 2020 Paritala, Yarlagadda, Kansky, Wang, Mendieta, Gu, McGahan, Lloyd and Li.)

A patient-specific carotid bifurcation with tandem stenosis found at both internal carotid artery (ICA) and common carotid artery (CCA) was studied. The in vivo pre-carotid endarterectomy (pre-CEA) multi-spectral magnetic resonance imaging (MRI) were performed and in vitro post-CEA carotid plaque tissue sample was collected. MR imaging data and tissue sample staining histology were used to recognize the plaque components. Further, the computational fluid dynamics (CFD) were performed on four MR-based reconstructed 3D carotid bifurcation models (the patient-specific geometry with tandem stenosis and three presumptive geometries by removing the stenosis part). The flow and shear stress behavior affected by the tandem stenosis was analyzed. From the results of MR segmentation and histology analysis, plaque lipid pool and calcification were found at both ICA and CCA. From the result of CFD simulation, the flow shear stress behavior suggested the tandem stenosis as a more "dangerous" situation than a single-stenosis artery. Besides, the CFD results deduced that the stenosis at the CCA location formed initially and led to the subsequent formation of stenosis at ICA. This study suggests that when planning CEA, CFD simulation on the presumptive models could help clinicians to estimate the blood flow behavior after surgery. Particular attention should be paid to the case of tandem stenosis, as the local hemodynamic environment is more complex and treatment of one stenosis may lead to a variation in the hemodynamic loading on the second plaque, which may result in either a higher risk of plaque rupture or restenosis., (Copyright © 2019 Wang, Paritala, Mendieta, Gu, Raffel, McGahan, Lloyd and Li.)

Background: Median arcuate ligament syndrome (MALS) is a condition characterized by chronic abdominal symptoms associated with median arcuate ligament compression of the celiac artery. The selection of patients is difficult in the management of MALS. This study aimed to identify factors that predict outcomes of surgical and nonoperative treatment in these patients., Methods: Patients referred with a possible diagnosis of MALS between 1998 and 2013 were identified retrospectively. Only patients with chronic symptoms and radiologically confirmed celiac artery compression were included. The clinical features, investigations, and management were documented. Outcome was assessed using the Visick score, Gastrointestinal Symptom Rating Scale, and 12-Item Short Form Health Survey by telephone interview and review of medical records., Results: There were 67 patients, 43 (64%) treated surgically and 24 (36%) managed without surgery, with a median follow-up of 25 months and 24 months, respectively. After surgical treatment, 16 (37%) were asymptomatic, 24 (56%) were partially improved, 3 (7%) had no changes in symptoms, and none had worsening of symptoms. Postexertional pain predicted improvement after surgery (P = .022). Vomiting (P = .046) and unprovoked pain (P = .006) were predictors of poor surgical outcome. After nonoperative management, 1 (4%) was asymptomatic, 7 (29%) were partially improved, 12 (50%) had no changes in symptoms, and 4 (17%) had worsening of symptoms. No outcome predictors of nonoperative treatment were identified., Conclusions: MALS was more likely to respond to decompression if patients had postexertional pain. Patients who presented with vomiting and unprovoked pain were unlikely to respond to surgery. In contrast with previous studies, postprandial pain was not found to be predictive of outcome., (Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.)

There have been few reported cases of management of an aortobronchial fistula. We describe the case of a 68 year-old male with a very high operative risk who had a successful staged management of a primary aortobronchial fistula. An endovascular stent was placed initially, however due to recurrence of the fistula a second stent was deployed within the first one some three months after. Fifteen months later he represented with massive haemoptysis, severe cachexia and at this stage the best course of surgical management was thought to be lobectomy via thoracotomy followed by trapezius flap overlay covering the exposed stent and separating it from the remaining lung., (Copyright © 2012 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.)

Chronic lymphocytic leukemia (CLL) B cells that express unmutated immunoglobulin heavy-chain variable region genes (IgV(H)) generally express ZAP-70, in contrast to normal B cells or most CLL cases with mutated IgV(H). Following IgM ligation, ZAP-70+ CLL cells had significantly higher levels of phosphorylated p72(Syk), BLNK, and phospholipase-Cgamma (PLCgamma) and had greater[Ca2+]i flux than did ZAP-70-negative CLL cases, including unusual ZAP-70-negative cases with unmutated IgV(H). IgM ligation of ZAP-70-negative CLL B cells infected with an adenovirus vector encoding ZAP-70 induced significantly greater levels of phosphorylated p72(Syk), BLNK, and PLCgamma and had greater[Ca2+]i flux than did similarly stimulated, noninfected CLL cells or CLL cells infected with a control adenovirus vector. We conclude that expression of ZAP-70 in CLL allows for more effective IgM signaling in CLL B cells, a feature that could contribute to the relatively aggressive clinical behavior generally associated with CLL cells that express unmutated IgV(H).

Objective: Laryngeal and tongue function was assessed in 28 patients to evaluate the presence, nature, and resolution of superior recurrent laryngeal and hypoglossal nerve damage resulting from standard open primary carotid endarterectomy (CEA)., Methods: The laryngeal and tongue function in 28 patients who underwent CEA were examined prospectively with various physiologic (Aerophone II, laryngograph, tongue transducer), acoustic (Multi-Dimensional Voice Program), and perceptual speech assessments. Measures were obtained from all participants preoperatively, and at 2 weeks and at 3 months postoperatively., Results: The perceptual speech assessment indicated that the vocal quality of "roughness" was significantly more apparent at the 2-week postoperative assessment than preoperatively. However, by the 3-month postoperative assessment these values had returned to near preoperative levels, with no significant difference detected between preoperative and 3-month postoperative levels or between 2-week and 3-month postoperative levels. Both the instrumental assessments of laryngeal function and the acoustic assessment of vocal quality failed to identify any significant difference on any measure across the three assessment periods. Similarly, no significant impairment in tongue strength, endurance, or rate of repetitive tongue movements was detected at instrumental assessment of tongue function., Conclusions: No permanent changes to vocal or tongue function occurred in this group of participants after primary CEA. The lack of any significant long-term laryngeal or tongue dysfunction in this group suggests that the standard open CEA procedure is not associated with high rates of superior recurrent and hypoglossal nerve dysfunction, as previously believed.

Purpose: To report the results of a postmortem examination in a patient who died of unrelated causes 7 months following endoluminal treatment of an infrarenal abdominal aortic aneurysm (AAA)., Methods: As part of an FDA Phase I pilot study, a 73-year-old man underwent successful endoluminal exclusion of an infrarenal AAA using a 9-cm-long endograft (Endovascular Grafting System). Seven months later, he succumbed to complications of a spontaneous esophageal rupture. At autopsy, the aorta was dissected in situ by a vascular surgeon and pathologist before being explanted in order to examine the wound healing characteristics at the aorta-endograft interface. Particular attention was also directed to the hooks composing the attachment system at each end of the endograft., Results: Macroscopic and microscopic examination revealed that the graft had completely excluded the aneurysm sac from the circulation and was incorporated into the aortic wall at the proximal neck and distal cuff. A smooth pannus of endothelial cells covered the proximal end of the endograft at the areas of contact with the aorta, while microscopic examination of the distal end of the graft revealed poorly formed, fibrinous pannus. The neointima deep to the endothelium consisted of a collagenous matrix containing myofibroblasts and histiocytes, providing evidence of healing between the endograft and aorta. Both renal arteries were clear of the proximal end of the endograft, but a previously unrecognized right lower pole renal artery with an extremely caudal origin was excluded from the aortic lumen. Each hook of the attachment system was seen protruding through the adventitia of the aorta. There was no evidence of trauma to the aortic wall or the surrounding tissues caused by these hooks., Conclusion: There appears to be evidence that an endoluminally placed aortic graft may be incorporated by the host aortic tissue.

A 62-year-old male patient was admitted with acute dissociation of the descending thoracic aorta and an infrarenal abdominal aortic aneurysm (AAA). Investigation revealed that the thoracic dissection probably had arisen retrogradely in the posterior wall of the AAA and extended superiorly to the left subclavian artery as a blind sac. Implantation of an endoluminal graft device below the renal arteries enabled simultaneous treatment of the AAA and the thoracic aortic dissection. The patient had an uncomplicated recovery. Postoperative aortography and computed tomography demonstrated normal flow through the aorta and endograft without leak of contrast into the AAA sac or the false lumen of the dissection. Contrast computed tomography 6 months after operation demonstrated that the false lumen was no longer evident.

Purpose: The aim of this study was to report early experiences with the Sydney and Endovascular Technologies (EVT) prostheses for the treatment of abdominal aortic aneurysms (AAA) deemed suitable for endoluminal tube graft repair., Methods: Consecutive endoluminal tube graft repairs were analyzed over the first 12 months in which the Sydney and EVT prostheses were used. Patients eligible for the EVT prosthesis had type I AAAs: a proximal neck length > or = 2 cm, a distal cuff length > or = 1.5 cm, and nontortuous iliac arteries > or = 8 mm. Selection criteria for the Sydney device were more liberal and included AAAs that had distal cuffs < 1.5 cm. During the study period, 28 of 91 patients evaluated for AAA repair were thus selected for endoluminal grafting: 18 patients received the Sydney endograft and 10 the EVT device. Medical comorbidities were present in slightly less than one third of patients in both groups. Contrast-enhanced computerized tomography (CT) was performed preoperatively, within 10 days of operation, and at 6 and 12 months postprocedure., Results: All endografts were successfully deployed in both groups. Postprocedural CT scans revealed incomplete aneurysm exclusion in four patients with the Sydney endograft. Subsequent deployment of a second endograft sealed these "leaks" in two cases; the other two were converted to open repair (89% clinical success). No leaks were seen with the EVT device. Local/vascular complications occurred in 33% of the Sydney group compared with 20% for the EVT device (p = 0.001); systemic sequelae were more common in the EVT group (30% versus 17% in the Sydney cohort, p = 0.002). There were no deaths within 30 days; three late deaths were not procedure related., Conclusion: AAAs that are suitable for endoluminal tube graft repair may be treated with a high rate of initial success with either the Sydney or EVT prostheses. More liberal selection criteria may increase the likelihood of local/vascular complications.

Purpose: The aim of this study was to analyze the causes of failure of endoluminal grafting for abdominal aortic aneurysms (AAA) and to put forward proposals for preventing these failures., Methods: Since May 1992, endoluminal repair of aneurysms was undertaken in 47 patients. Forty-three of these patients had AAAs and are the basis of this study. All procedures were nonurgent and were performed in the operating room with the patient draped for an open repair in the event of failed endoluminal repair. Radiographic guidance was used to pass the endografts into the aorta via a delivery sheath introduced through the femoral or iliac arteries. The configuration of the endografts was tubular (n = 28), tapered aortoiliac/aortofemoral (n = 11), and bifurcated (n = 4)., Results: Successful endoluminal repair was achieved in 34 of 43 (79%) patients. The remaining nine were terminated in favor of an open repair. The causes of failure were problems with access (2), balloon malfunction (1), stent dislodgment (3), graft thrombosis (1), and inability to deploy the contralateral limb of a bifurcated graft (2). All failed endoluminal repairs proceeded to successful open repair. There was no perioperative mortality in patients undergoing endoluminal repair or in those whose endoluminal repair was converted to open operation., Conclusions: The failures of endoluminal grafting have been analyzed. Methods of avoiding access problems, balloon malfunction, and stent dislodgment have been defined and recommendations made.

Endogenous ligands complicate radioligand-binding assays of high-affinity binding proteins by obscuring binding sites or by diluting the labeled ligand. We have developed a mathematical model for such systems where radioligand and endogenous ligand are structurally identical. Data which relate radioligand binding at equilibrium as a function of sample volume can be plotted such that the concentrations of endogenous ligand and binder are graphically determined; however, a more precise determination may be done by nonlinear regression with the aid of a microcomputer. The method is demonstrated for the assay of biotin-binding proteins in the presence of a range of endogenous biotin concentrations below and above that required to saturate the binding sites.

1. Riboflavin-binding protein (RBP) has been isolated for the first time from reptilian sources. 2. RBP from eggs of Python molurus (Indian python) and Chrysemys picta (painted turtle) has been isolated and compared to RBP from Gallus gallus domesticus (chicken), a well-characterized protein, and a newly isolated RBP from Cairina moschata (Muscovy duck). 3. Each of the proteins is phosphorylated and glycosylated. 4. The ratio of riboflavin binding to protein is 1:1 and the KD for each protein is between 1-3 nM. 5. The mol. wts, different for each species, range from 30,000-40,000, with the reptilian proteins being approx. 10,000 larger than the avian proteins.