On the Importance of Including Cohesive Zone Models in Modelling Mixed-Mode Aneurysm Rupture.

INTRODUCTION: The precise mechanism of rupture in abdominal aortic aneurysms (AAAs) has not yet been uncovered. The phenomenological failure criterion of the coefficient of proportionality between von Mises stress and tissue strength does not account for any mechanistic foundation of tissue fracture. Experimental studies have shown that arterial failure is a stepwise process of fibrous delamination (mode II) and kinking (mode I) between layers. Such a mechanism has not previously been considered for AAA rupture. METHODS: In the current study we consider both von Mises stress in the wall, in addition to interlayer tractions and delamination using cohesive zone models. Firstly, we present a parametric investigation of the influence of a range of AAA anatomical features on the likelihood of elevated interlayer traction and delamination. RESULTS: We observe in several cases that the location of peak von Mises stress and tangential traction coincide. Our simulations also reveal however, that peak von Mises and intramural tractions are not coincident for aneurysms with Length/Radius less than 2 (short high-curvature aneurysms) and for aneurysms with symmetric intraluminal thrombus (ILT). For an aneurysm with (L/R = 2.0), the peak σ vm moves slightly towards the origin while the peak T t is near the peak bulge with a separation distance of ~ 17 mm. Additionally, we present three patient-specific AAA models derived directly from CT scans, which also illustrate that the location of von Mises stress does not correlate with the point of interlayer delamination. CONCLUSION: This study suggests that incorporating cohesive zone models into clinical based FE analyses may capture a greater proportion of ruptures in-silico.

Influence of shape-memory stent grafts on local aortic compliance.

The effect of repair techniques on the biomechanics of the aorta is poorly understood, resulting in significant levels of postoperative complications for patients worldwide. This study presents a computational analysis of the influence of Nitinol-based devices on the biomechanical performance of a healthy patient-specific human aorta. Simulations reveal that Nitinol stent-grafts stretch the artery wall so that collagen is stretched to a straightened high-stiffness configuration. The high-compliance regime (HCR) associated with low diastolic lumen pressure is eliminated, and the artery operates in a low-compliance regime (LCR) throughout the entire cardiac cycle. The slope of the lumen pressure-area curve for the LCR post-implantation is almost identical to that of the native vessel during systole. This negligible change from the native LCR slope occurs because the stent-graft increases its diameter from the crimped configuration during deployment so that it reaches a low-stiffness unloading plateau. The effective radial stiffness of the implant along this unloading plateau is negligible compared to the stiffness of the artery wall. Provided the Nitinol device unloads sufficiently during deployment to the unloading plateau, the degree of oversizing has a negligible effect on the pressure-area response of the vessel, as each device exerts approximately the same radial force, the slope of which is negligible compared to the LCR slope of the native artery. We show that 10% oversizing based on the observed diastolic diameter in the mid descending thoracic aorta results in a complete loss of contact between the device and the wall during systole, which could lead to an endoleak and stent migration. 20% oversizing reaches the Dacron enforced area limit (DEAL) during the pulse pressure and results in an effective zero-compliance in the later portion of systole.

A Dual-VENC Four-Dimensional Flow MRI Framework for Analysis of Subject-Specific Heterogeneous Nonlinear Vessel Deformation.

Advancement of subject-specific in silico medicine requires new imaging protocols tailored to specific anatomical features, paired with new constitutive model development based on structure/function relationships. In this study, we develop a new dual-velocity encoding coefficient (VENC) 4D flow MRI protocol that provides unprecedented spatial and temporal resolution of in vivo aortic deformation. All previous dual-VENC 4D flow MRI studies in the literature focus on an isolated segment of the aorta, which fail to capture the full spectrum of aortic heterogeneity that exists along the vessel length. The imaging protocol developed provides high sensitivity to all blood flow velocities throughout the entire cardiac cycle, overcoming the challenge of accurately measuring the highly unsteady nonuniform flow field in the aorta. Cross-sectional area change, volumetric flow rate, and compliance are observed to decrease with distance from the heart, while pulse wave velocity (PWV) is observed to increase. A nonlinear aortic lumen pressure-area relationship is observed throughout the aorta such that a high vessel compliance occurs during diastole, and a low vessel compliance occurs during systole. This suggests that a single value of compliance may not accurately represent vessel behavior during a cardiac cycle in vivo. This high-resolution MRI data provide key information on the spatial variation in nonlinear aortic compliance, which can significantly advance the state-of-the-art of in-silico diagnostic techniques for the human aorta.

Quantification of the regional bioarchitecture in the human aorta.

Regional variance in human aortic bioarchitecture responsible for the elasticity of the vessel is poorly understood. The current study quantifies the elements responsible for aortic compliance, namely, elastin, collagen and smooth muscle cells, using histological and stereological techniques on human tissue with a focus on regional heterogeneity. Using donated cadaveric tissue, a series of samples were excised between the proximal ascending aorta and the distal abdominal aorta, for five cadavers, each of which underwent various staining procedures to enhance specific constituents of the wall. Using polarised light microscopy techniques, the orientation of collagen fibres was studied for each location and each tunical layer of the aorta. Significant transmural and longitudinal heterogeneity in collagen fibre orientations were uncovered throughout the vessel. It is shown that a von Mises mixture model is required accurately to fit the complex collagen fibre distributions that exist along the aorta. Additionally, collagen and smooth muscle cell density was observed to increase with increasing distance from the heart, whereas elastin density decreased. Evidence clearly demonstrates that the aorta is a highly heterogeneous vessel which cannot be simplistically represented by a single compliance value. The quantification and fitting of the regional aortic bioarchitectural data, although not without its limitations, including mean cohort age of 77.6 years, facilitates the development of next-generation finite element models that can potentially simulate the influence of regional aortic composition and microstructure on vessel biomechanics.

Late Dacron Patch Inflammatory Reaction after Carotid Endarterectomy.

OBJECTIVE: The aim was to analyse the incidence and presentation of carotid patch inflammatory reactions following carotid endarterectomy (CEA). METHODS: This was a cohort study using a prospectively maintained database. All patients who underwent elective CEA at a tertiary vascular centre between 2002 and 2016 were included. Computed tomography scan angiogram, duplex scan, and leucocyte scintigraphy were used to assess patients with suspected inflammatory patch complications. Re-intervention procedures and outcomes were noted. Histopathology and organisms cultured from the harvested material during re-intervention were assessed. RESULTS: During the study period, 633 patients underwent elective CEA. Fifty-one underwent eversion endarterectomy: 111 did not require a patch, whereas 471 patients had a patch repair. Four hundred and twenty eight had a Dacron patch repair and 43 a biological patch. Eight patients returned with late Dacron patch inflammatory complications (1.3% of all CEA and 1.9% of Dacron patch closures) after a period ranging from 18 months to 7 years (mean 4.1 ± 2.1 years). Seven of the eight patients underwent surgical re-intervention, and the eighth patient was deemed high surgical risk. One patient underwent a vein bypass, three had vein patch repair, one required internal carotid artery (ICA) ligation after patch excision, and two were managed by debridement, with omohyoid and sternomastoid muscle covering of the patch. The patient who required ICA ligation suffered a fatal stroke. The remaining patients had a satisfactory outcome. All patients showed evidence of foreign body reaction in pathological examination with no pathological organism cultured from swabs or tissue harvested during surgery. CONCLUSION: Late wound complications after CEA may be related to inflammatory reaction of the Dacron patch rather than infection. Infection should be excluded first. Reconstruction with vein is effective. However, debridement with sternomastoid and omohyoid muscle covering of the patch may be considered in high risk patients after exclusion of infection with regular follow-up.

The Role of Sequential Pneumatic Compression in Limb Salvage in Non-reconstructable Critical Limb Ischemia.

OBJECTIVE: Critical limb ischemia (CLI) is an increasingly alarming presentation of advanced generalized circulatory failure. Most patients presenting with CLI have profound cardiovascular comorbidities that hinder surgical intervention. Moreover, some patients present with non-reconstructable arterial anatomy. For this vulnerable cohort, primary amputation is often the only available option. This study aims at answering the question: Can sequential pneumatic compression (SPC) preclude amputation? METHODS: A retrospective analysis of 187 patients (262 limbs) prescribed the Artassist SPC compared outcomes between the group of patients who acquired the device and those who did not. The primary end point was limb salvage; secondary end points were amputation-free survival and improvement in toe pressures. RESULTS: The mean age was 74.78 years, the median follow-up was 16 months, and the median duration of usage was 4 months. 81.72% of the patient acquired the device and 18.28% did not. The mean toe pressure was 61.4 mmHg pre-application, and 65 mmHg after application (p = .071). Amputation-free survival was 98% and 96% for those who acquired the device and 90% and 84% for those who did not at 6 and 12 months, respectively. There was a non-significant association between limb salvage and device acquisition (p = .714); however, there was a significant improvement in rest pain (p < .0001), reduction in minor amputation (p = .023), and amputation-free survival associated with using the device (p = .01). CONCLUSIONS: Although limb salvage is the paramount ambition for patients referred to vascular services, some patients with CLI are better served with primary amputation. Although the mechanism of SPC action is still ambiguous, there is strong evidence to support its role in preventing minor amputation, prolonging amputation-free survival, and improving rest pain in patients with non-reconstructable CLI; nevertheless, its role in prevention of major amputation lacks statistical significance.

Ten-year experience in subclavian revascularisation. A parallel comparative observational study.

INTRODUCTION: Subclavian stenosis has a prevalence of approximately 2% in the community, and 7% within a clinical population. It is closely linked with hypertension and smoking. There is a relative paucity of published data to inform clinicians on the optimal mode of treatment for subclavian artery stenosis. OBJECTIVES: To compare clinical outcomes of subclavian bypass surgery with that of subclavian endovascular re-vascularisation. Endpoints were survival time, re-intervention-free survival, and symptom-free survival. METHOD: In all, 21 subclavian interventions were performed from 2000 to 2010. We compared angioplasty vs angioplasty with stenting vs bypass. RESULTS: Technical success was 100% in all groups. Symptom-free survival, at 70 months, was 60% in the angioplasty group, 100% in the angioplasty and stenting group and 75% in the bypass group. Re-intervention rate was 40% in the angioplasty group, 0% in the angioplasty and stenting group and 25% in the bypass group. Median time for re-intervention was 9.5 months in angioplasty patients and 36 months in bypass patients (p = 0.102). Target lesion revascularisation was 20.0% for angioplasty procedures, 16.67% for angioplasty and stenting and 25% for bypass procedures. CONCLUSION: Angioplasty with stenting provides improved symptom-free survival and freedom from re-intervention in patients with symptomatic subclavian artery stenosis.

An Experimental Evaluation of Device/Arterial Wall Compliance Mismatch for Four Stent-Graft Devices and a Multi-layer Flow Modulator Device for the Treatment of Abdominal Aortic Aneurysms.

OBJECTIVE/BACKGROUND: To investigate experimentally the arterial wall/device compliance mismatch of four stent-graft devices and a multilayer flow modulator within the supra- and infrarenal locations for the treatment of abdominal aortic aneurysms (AAA). METHODS: Five devices (MFM, EndurantII, Excluder, Zenith, and Fortron) were tested under physiological flow conditions within a flow simulator system comprising of a patient-specific thin-walled flexible AAA perfusion model with replicated intraluminal thrombus, supported by the spinal column. Devices were submitted to circumferential force tests and implanted in the perfusion model for circumferential arterial pressure/diameter measurements. Parameters, including radial resistive force, supra-/infrarenal compliance, pulsatile arterial energy loss (PAEL), pulse wave velocity (PWV), and wave reflection coefficient (Γ), were computed to characterise the devices' performance. RESULTS: The Zenith and EndurantII devices had the highest radial resistive force (up to 3 N/cm), while the Fortron device had the lowest (0.11 N/cm). Supra- and infrarenal compliance varied between 6.9-5.1 × 10(-4)/mmHg and 4.8-5.4 × 10(-4)/mmHg, respectively. Two devices (EndurantII and Excluder) significantly decreased infrarenal compliance by 13-26% (p < .001). Four devices increased the PAEL by 13-44% (p < .006). The PWV ranged from 10.9 m/s (MFM; p = .164) to 15.1 m/s (EndurantII; p < .001). There was an increase of 8-238% (p < .001) in the reflection coefficient for all devices. CONCLUSION: Commercially available endovascular devices lower the aortic wall compliance after implantation. The MFM was found to be the most compliant in the suprarenal region, while the Fortron device was the most compliant in the infrarenal region. Choosing the most compliant devices for treating AAAs produces positive gains in the aortic elastic recoil, thus minimising the device related complications.

Contemporary management of critical lower limb ischemia in TASC D lesions with subintimal angioplasty in femoro-popliteal lesions, tibial angioplasty and sequential compression biomechanical device for infra-inguinal arterial occlusion. Experience and quality of life outcome learned over 25 years.

AIM: Patients with end-stage critical limb ischemia (CLI) survive on borrowed time and amputation is inevitable if an aggressive management stratagem is not instigated. Our primary aim was to equate effectiveness of subintimal angioplasty (SIA) and tibial balloon angioplasty (TBA) in sustaining clinical improvement and amputation free survival (AFS) in patients with CLI TASD II D. Moreover, patients with severe CLI, who were not suitable for revascularization and who were offered therapy with a sequential compression biomechanical device (SCBD) were scrutinised as part of a comprehensive lower limb salvage program. METHODS: From 2002-2012, 5876 patients were referred with peripheral vascular disease (PVD); 987 presented with CLI and 798 had intervention; 189 patients presenting with CLI were not candidates for revascularisation, out of which 171 were offered SCBD. We formed a prospective observational group study of 441 patient who had TASC D disease. All of these patients presented as emergencies and were allocated to the next available treatment list. Duplex ultrasound arterial mapping (DUAM) was the sole preoperative investigation tool in 92% of all cases. Of the 441 patients studied, 190 patients (206 procedures) has SIA for TASC D femero-popliteal occlusions, 80 patients (89 procedures) had TBA and cool eximer laser angioplasty (CELA) for tibial artery occlusions and 171 patients with severe CLI were not suitable for revascularization and joined the SCBD program. Mean age (SIA 73±13 years vs. TBA/CELA 74±8 years vs. SCBD 75±13 years), and comorbidity severity scores (P>0.05) were similar between groups. RESULTS: Perioperative mortality within the SIA group was 1.6% vs. 0% within the TBA group and 0.6% in SCBD. Length of hospital stay within the TBA group was 3.8±2 days vs. SIA 14±16 days, P<0.0001. The 5-year freedom from major adverse events (MAE) for the SIA group was 68% that was comparable to the results obtained for both the TBA group; 59%, and SCBD group: 62.5% (P=0.1935). Five-year freedom from target lesion revascularization was 85.9% within the SIA group and 79% within the TBA group. A sustained clinical improvement was seen in 82.8% of primary SIA and 68% of TBA, which mimics the outcome of SCBD at 68% at one year. A total of 83% SCBD patients had no rest pain within one week of starting the program and gangrene remained dry and non-progressive. Ulceration healed in all but 12 patients. There were no device-related complications. Limb salvage was 94% at 5 years. All-cause survival was 69%. Quality time spent without symptoms of disease or toxicity of treatment (Q-TWiST) was 24.7 months for SIA and 8.5 months for TBA and was 38.13 for SCBD for a total of 708 months of usage. Cost per quality adjusted-life years (QALY) for SIA was € 5662.79, € 12,935.18 for TBA and € 2943.56 for SCBD. CONCLUSION: All treatment pathways augmented patient-specific Q-TWiST with substantial cost reduction. SIA, TBA and SCBD expand AFS and symptom-free survival. All treatment modalities are minimally invasive and allow for a high patient turnover without compromising limb salvage, once they are performed by experienced vascular surgeons in high deliberate practice volume centers.

Secondary aortoduodenal fistula following endovascular repair of inflammatory abdominal aortic aneurysm due to Streptococcus anginosus infection: A case report and literature review.

INTRODUCTION: Aortoenteric fistula is a rare but very serious complication of both surgical and endovascular abdominal aortic reconstruction. Since the advent of endovascular abdominal aortic aneurysm repair (EVAR), 20 cases of aortoduodenal fistula associated with aortic stent grafts have been reported.(1) However, only a handful has been reported following inflammatory abdominal aortic aneurysm repair. It most commonly presents with bleeding, usually from the upper gastro-intestinal tract. With recent advances in the screening, diagnosis and management of abdominal aortic aneurysms either surgically or through an endovascular approach, the diagnosis of an aortoduodenal fistula in patients with gastro-intestinal bleeding must be suspected and excluded. PRESENTATION OF CASE: We describe a case of secondary aortoduodenal fistula that occurred two and a half years following endovascular stent graft repair of an inflammatory abdominal aortic aneurysm. We also outline the emergency correction plan and the attempts at repair. DISCUSSION: This case defies the general concept that patients with inflammatory abdominal aortic aneurysms are relatively immune to rupture. Although the presence of a peri-aneurysm thick inflammatory membrane decreases the possibility of rupture, these patients are more susceptible to other related complications such as aorto-enteric and aorto-caval fistulas.(2) This case also demonstrates the peculiar presence of Streptococcus anginosus as the pathological organism leading to graft infection and subsequent fistula, as opposed to enterococci which are often found in endograft infection. CONCLUSION: Aorto-enteric fistulas are associated with a grave prognosis. Early diagnosis is crucial and extra vigilance should be taken in cases of inflammatory AAA.

Endovascular aneurysm repair for multiple aneurysms as a sequel of hypereosinophilic syndrome.

This case represents the first report of multiple arterial aneurysms including aortic, iliac, visceral, and coronary aneurysms associated with hypereosinophilic syndrome. It presents an interesting case of epinephrine abuse and the unfortunate sequelae. This case illustrates novel approaches in emergency repair of internal iliac artery aneurysm rupture and the management of visceral artery aneurysms and exemplifies how multiple endovascular technologies can be utilized even in the high-risk polymorbid patient.

Early mid-term results of the first 103 cases of multilayer flow modulator stent done under indication for use in the management of thoracoabdominal aortic pathology from the independent global MFM registry.

AIM: We report mid-term results from the Global Independent multilayer flow modulator (MFM) registry using a uni-modular multilayer flow modulator stent technology. METHODS: We present the first 103 cases out of the 380 cases implanted in Europe under indications for use. All were done on a compassionate basis, in 12 countries, and were fully analyzed through the MFM registry. Primary endpoints were: one-year freedom from rupture and aneurysm-related death, one year all cause mortality, patency of visceral branches at one year, and one year incidence of stroke and paraplegia. Primary technical endpoints were aneurysm sac volume modulation at one year. Secondary technical endpoints were technical success and one-year freedom from reintervention. Mean age of 69.2 years (16-93 years), mean aneurysm diameter was 6.4±1.66 cm and mean length was 12.96 cm. They were 75 Crawford thoracoabdominal aortic aneurysms (TAAA) (11 Type I, 14 Type II, 26 Type III, and 24 Type IV), 7 arch aneurysms, 15 suprarenal aortic aneurysms and 6 type B dissections. The mean number of side branches covered for a total number of 378 branches is 3.7 side branches per case. Total numbers of stents used was 176 with a mean of 1.71 MFM stents per case; 77.77 were ASA IV E, 72.7% had previous thoracic endovascular aortic repair or open TAAA repair. RESULTS: Thirty-day morbidity was 5.4% with zero mortality. Aneurysm related survival was 91.7% at one year. No rupture occurred. Four cases of consumptive coagulopathy were observed, two of which resulted in death from hemorrhagic cerebrovascular stroke and one of which resulted in death from a gastrointestinal bleed. Technical success was 97.3%. One-year all-cause survival was 86.8%. At 12 months 95.1% of all visceral branches were patent. There were no stent fractures. One-year intervention free survival was 89.4%. At six months the mean rate of sac volume increase was 0.57%% per month, resulting in a mean volume increase of 2.56%. At 12 months the rate of increase had slowed to 0.33% per month, resulting in a total average increase in sac volume of 5.07%. Mean base line thrombus volume was 297.54 cm3. At one year the mean thrombus volume was 361.38 cm3 with mean volume change of 63.45 cm3. However, mean base line total volume was 332.79 cm3. At one year the mean total volume was 355.4 cm3 with a mean total volume change of 22.61 cm3. The mean base line maximum diameter was 6.27 cm. At one year mean maximum diameter was 7.06 cm with mean total change of 0.79 cm3. The mean baseline residual flow volume was 71.75 cm3. At one year, mean residual flow volume had decreased to 63.3cm3 with mean volume change of 8.4 cm3. CONCLUSION: Increasing sac volume, thrombus or diameter size was not associated with rupture. MFM implantation instigates a process of aortic remodeling involving initial thrombus deposition, which slows between six and twelve months. This Global MFM Registry data has demonstrated the proof of concept of this disruptive technology.

Preoperative vascular screening in the presence of aortic, carotid and peripheral pathology for patients undergoing their first arterial intervention: 18 month follow-up.

BACKGROUND: The aim of this paper was to determine prevalence and incidence of intervention required for concomitant Asymptomatic Vascular Disease (AVD) on patients undergoing their first elective peripheral arterial intervention. METHODS: This is a prospective observational study Data was obtained on patients undergoing peripheral revascularisation, abdominal aortic aneurysmal (AAA) repair or carotid procedure from 2006 to 2009. Of 542 complex arterial procedures, 328 patients had their first vascular intervention. (PAD=127, AAA=97, CAD=83, concomitant AAA and PAD=21). Primary endpoint is detection of any concomitant asymptomatic AAA, CAS or PAD. Secondary endpoints are need for intervention of AVD detected on screening, and major adverse clinical events during follow-up. RESULTS: Prevalence of AVD detected was 13% PAD, 51% CAS and 8%AAA. Symptomatic and Asymptomatic PolyVasBed patients had 11.4- and 8.16-fold increased likelihood for detection of asymptomatic CAS respectively (P<0.0001) relative to the remaining study population. Asymptomatic PolyVasBed patients had 8.2 fold increased likelihood of asymptomatic AAA, P<0.0001, compared to the remaining study population. Likelihood for intervention in Asymptomatic PolyVasBed is OR 5.740 (P=0.044) and Symptomatic PolyVasBed is OR 4.500 (P<0.001). Asymptomatic AAA detected in both symptomatic and asymptomatic vascular disease patients, is the strongest predicting factor of intervention in 18 months follow-up. In Asymptomatic PolyVasBed patients, CAS and AAA have the highest prevalence. CONCLUSIONS: Screening for AVD is mandatory prior to any vascular intervention.

A role for MRP8 in in stent restenosis in diabetes.

OBJECTIVE: The most common cause of death in diabetes mellitus is cardiovascular disease. Patients frequently undergo vascular intervention such as stenting. The occurrence of in stent restenosis (ISR) has been reduced by the use of drug eluting stents in non-diabetic patients but the incidence of restenosis and stent thrombosis remains higher in diabetic patients. We investigated the pathogenesis of in stent restenosis in an animal model of type 2 diabetes mellitus. METHODS AND RESULTS: Stents were placed in Zucker Fatty rat (ZFR) and wild type rat carotid arteries, and tissues were harvested 14 days post surgery for morphometric analysis. Unstented carotid arteries from both groups were harvested for microarray analysis. In vitro apoptosis, proliferation and migration assays were performed on rat and human aortic endothelial cells (EC). ZFRs developed an exaggerated intimal response to stent placement compared to wild type controls 14 days post stent placement. MRP8 and MRP14 were up-regulated in unstented ZFR carotid arteries in comparison to controls. Expression of MRP8/14 was also elevated in EC exposed to high glucose conditions. EC function was impaired by high glucose concentrations, and this effect could be mimicked by MRP8 over-expression. MRP8 knockdown by shRNA significantly restored EC function after exposure to high glucose concentrations. MRP8 expression in glucose exposed cells was also inhibited using pharmacological blockade of glucose-induced pathways. CONCLUSIONS: EC dysfunction caused by elevated glucose levels could be mimicked by MRP8/14 over-expression and reversed/prevented by MRP8 knockdown. Thus, MRP8/14 likely plays a role in exaggerated ISR in diabetes mellitus, and MRP8 inhibition may be useful in improving outcome after stent placement in diabetes mellitus.

Phosphoinositide 3-kinase signaling is critical for ErbB3-driven breast cancer cell motility and metastasis.

Many malignancies show increased expression of the epidermal growth factor (EGF) receptor family member ErbB3 (HER3). ErbB3 binds heregulin ß-1 (HRGß1) and forms a heterodimer with other ErbB family members, such as ErbB2 (HER2) or EGF receptor (EGFR; HER1), enhancing phosphorylation of specific C-terminal tyrosine residues and activation of downstream signaling pathways. ErbB3 contains six YXXM motifs that bind the p85 subunit of phosphoinositide 3 (PI3)-kinase. Previous studies demonstrated that overexpression of ErbB3 in mammary tumor cells can significantly enhance chemotaxis to HRGß1 and overall metastatic potential. We tested the hypothesis that ErbB3-mediated PI3-kinase signaling is critical for heregulin-induced motility, and therefore crucial for ErbB3-mediated invasion, intravasation and metastasis. The tyrosines in the six YXXM motifs on the ErbB3 C-terminus were replaced with phenylalanine. In contrast to overexpression of the wild-type ErbB3, overexpression of the mutant ErbB3 did not enhance chemotaxis towards HRGß1 in vitro or in vivo. We also observed reduced tumor cell motility in the primary tumor by multiphoton microscopy, as well as a dramatically reduced ability of these cells to cross the endothelium and intravasate into the circulation. Moreover, whereas mutation of the ErbB3 C-terminus had no effect on tumor growth, it had a dramatic effect on spontaneous metastatic potential. Treatment with the PI3-kinase inhibitor PIK-75 similarly inhibited motility and invasion in vitro and in vivo. Our results indicate that stimulation of the early metastatic steps of motility and invasion by ErbB3 requires activation of the PI3-kinase pathway by the ErbB3 receptor.

Copine-III interacts with ErbB2 and promotes tumor cell migration.

ErbB2 amplification and overexpression in breast cancer correlates with aggressive disease and poor prognosis. To find novel ErbB2-interacting proteins, we used stable isotope labeling of amino acids in cell culture followed by peptide affinity pull-downs and identified specific binders using relative quantification by mass spectrometry. Copine-III, a member of a Ca(2+)-dependent phospholipid-binding protein family, was identified as binding to phosphorylated Tyr1248 of ErbB2. In breast cancer cells, Copine-III requires Ca(2+) for binding to the plasma membrane, where it interacts with ErbB2 upon receptor stimulation, an interaction that is dependent on receptor activity. Copine-III also binds receptor of activated C kinase 1 and colocalizes with phosphorylated focal adhesion kinase at the leading edge of migrating cells. Importantly, knockdown of Copine-III in T47D breast cancer cells causes a decrease in Src kinase activation and ErbB2-dependent wound healing. Our data suggest that Copine-III is a novel player in the regulation of ErbB2-dependent cancer cell motility. In primary breast tumors, high CPNE3 RNA levels significantly correlate with ERBB2 amplification. Moreover, in an in situ tissue microarray analysis, we detected differential protein expression of Copine-III in normal versus breast, prostate and ovarian tumors, suggesting a more general role for Copine-III in carcinogenesis.

A prospective feasibility study of duplex ultrasound arterial mapping, digital-subtraction angiography, and magnetic resonance angiography in management of critical lower limb ischemia by endovascular revascularization.

Duplex ultrasound arterial mapping (DUAM) allows precise evaluation of peripheral vascular disease (PVD). However, magnetic resonance angiography (MRA) and digital-subtraction angiography (DSA) are the diagnostic tools used most frequently prior to intervention. Our aim was to compare clinical pragmatism, hemodynamic outcomes, and cost-effectiveness when using DUAM alone compared to DSA or MRA as preoperative assessment tools for endovascular revascularization (EvR) in critical lower limb ischemia (CLI). From 2002 through 2005, 465 patients were referred with PVD. Of these, 199 had CLI and 137 required EvR. Preoperative diagnostic evaluation included DUAM (n = 41), DSA (n = 50), or MRA (n = 46). EvR was aortoiliac in 27% of cases and infrainguinal in 73%. Patients were assessed at day 1, 6 weeks, 3 months, and 6 months. Composite end points were relief of rest pain, ulcer/gangrene healing, and increase in perfusion pressure, as measured by ankle-brachial index (ABI) and digital pressures. Patency by DUAM, limb salvage, morbidity, mortality, length of stay, and cost-effectiveness were compared between groups using nonparametric t-test, analysis of variance, and Kaplan-Meier analysis. The three groups were comparable in terms of age, sex, comorbidity, and Society for Vascular Surgery/International Society of Cardiovascular Surgery clinical classification. Six-month mean improvement in ABI in the DUAM group was comparable to that in the DSA group (P = 0.25) and significantly better than that in the MRA group (P < 0.05). Six-month patency rates for the DUAM group were comparable to those in the DSA group (P = 0.68, relative risk [RR] = 0.74, 95% confidence interval [CI] 0.18-2.99) and superior to that in the MRA group (P = 0.022, RR = 0.255, 95% CI 0.09-0.71). Length of hospital stay was lower in the DUAM group compared with the DSA group (P < 0.0001) and the MRA group (P = 0.0003). The cost of DUAM is lower than that of both DSA and MRA. DUAM accurately identified the total number of target lesions for revascularization; however, MRA overestimated it. Our results indicate that DUAM is outstanding when compared with other available modalities as a preoperative imaging tool in a successful EvR program. DUAM is a minimally invasive preoperative evaluation for EvR and offers precise consecutive data with patency and limb salvage rates comparable to EvR based on DSA and superior to MRA. We believe that our feasibility study has established DUAM as an economically proficient primary modality for investigating patients with CLI that significantly shortens length of hospital stay.

Haemoglobin A1c (HbA1C) in non-diabetic and diabetic vascular patients. Is HbA1C an independent risk factor and predictor of adverse outcome?

BACKGROUND: Plasma Haemoglobin A1c (HbA1c) reflects ambient mean glycaemia over a 2-3 months period. Reports indicate that patients, with and without diabetes, with an elevated HbA1c have an increased risk of adverse outcome following surgical intervention. Our aim was to determine whether elevated plasma HbA1c level was associated with increased postoperative morbidity and mortality in patients undergoing vascular surgical procedures. METHODS: Plasma HbA1c was measured prospectively in 165 consecutive patients undergoing emergency and elective vascular surgical procedures over a 6-month period. Patients were categorized into four groups depending on whether their plasma HbA1c was < or =6%, 6.1-7%, 7.1-8% or >8% and clinical data was entered into a prospectively maintained database. Patients were also classified by diabetic status with suboptimal HbA1c in a patient without diabetes being >6 to < or =7% and suboptimal HbA1c in a patient with diabetes being >7%. Patients with plasma HbA1c >7% were reclassified as having undiagnosed diabetes mellitus. Composite primary endpoints were all cause 30-day morbidity and mortality and all cause 6-month mortality. Composite secondary endpoints were procedure specific complications, adverse cardiac events, stroke, infection and mean length of hospital stay. RESULTS: Of the 165 patients studied, 43 (26.1%) had diabetes and the remaining 122 (73.9%) did not. The mean age was 72 years and 59% were male. Suboptimal HbA1c levels were found in 58% patients without diabetes and in 51% patients with diabetes. In patients without diabetes those with suboptimal HbA1c levels (6-7%) had a significantly higher incidence of overall 30-day morbidity compared to patients with HbA1c levels < or =6% (56.5 vs 15.7%, p<0.001). Similarly, for patients with diabetes those with suboptimal HbA1c levels (HbA1c >7%) had a significantly higher incidence of 30-day morbidity compared to those with HbA1c levels < or =7% (59.1% vs 19%, p=0.018). Multivariate analysis revealed that a plasma HbA1c level of >6 to < or =7% was a significant independent predictor of overall 30-day morbidity in patients without diabetes undergoing vascular surgical procedures. No difference in mortality, composite secondary endpoints, procedure specific complications, stroke or mean length of hospital stay was observed between any of the groups in the study. CONCLUSION: Suboptimal HbA1c levels may hold prognostic significance in patients without diabetes undergoing vascular surgery.

The impact of differential expression of extracellular matrix metalloproteinase inducer, matrix metalloproteinase-2, tissue inhibitor of matrix metalloproteinase-2 and PDGF-AA on the chronicity of venous leg ulcers.

INTRODUCTION: Alteration in the expression of extracellular matrix metalloproteinase inducer (EMMPRIN), matrix metalloproteinase-2 (MMP-2), tissue inhibitors of matrix metalloproteinases (TIMP-2) and platelet derived growth factor (PDGF-AA) may contribute to poor healing in venous leg ulcers. AIM: The aim of this study is to determine the expression of EMMPRIN, MMP-2, TIMP-2 and PDGF-AA in the ulcer exudates and perivascular tissue of healing and non-healing chronic venous ulcers. PATIENTS, MATERIALS AND METHODS: Forty patients with chronic venous ulcers were included in this study, with a mean age of 60 years. Eleven patients were males and 29 were females. All patients had normal ankle brachial index and a venous ulcer of at least 8 weeks duration. Immuno-histochemistry using monoclonal antibodies to PDGF-AA, MMP-2, TIMP-2 and EMMPRIN was carried out on paraffin embedded punch biopsy skin specimens from the ulcer edge. Enzyme linked immunosorbent assay for PDGF, MMP-2 and TIMP-2 were carried out on wound fluids collected from patients. The ulcer size and character at the initial assessment and after 8 weeks were assessed to determine the status of ulcer healing. RESULTS: No significant difference was seen in the expression of TIMP-2, MMP-2 and EMMPRIN between the two groups. However, in the non-healing group high levels of MMP-2 and low levels of TIMP-2 in the wound fluid suggest a strong correlation of these two markers in the state of healing. Analysis of wound fluid by ELISA demonstrated high PDGF-AA in the healing group (p = 0.021). Significantly increased levels of PDGF-AA (p<0001) was noted in the perivascular area on immuno-histochemistry of healing ulcers. These data suggest that PDGF-AA plays an important role in healing of venous ulcers. CONCLUSION: Non-healing venous ulcers are associated with greater activity MMP-2 activity. The ratio of MMPs to their inhibitors TIMPs, dictate the rate of healing of the ulcers. PDGF-AA activity is associated with ulcer healing, though the mechanism is unclear. EMMPRIN expression in chronic venous ulcers probably parallels the chronicity of the condition rather than propagate it. However, further studies with larger samples are needed.

Recombinant factor VIIa in the treatment of intractable bleeding in vascular surgery.

Intractable bleeding unresponsive to conventional haemostatic measures is an uncommon but potentially life threatening surgical complication. Several studies have suggested that recombinant factor VIIa (rVIIa), a genetically engineered substitute for endogenous factor VIIa may have therapeutic application in patients with uncontrollable haemorrhage not previously diagnosed with coagulopathy. We report our experience of rVIIa use in eight such vascular surgery patients who developed life-threatening non-surgical haemorrhage either intra-operative or post-operatively. In all but one patient a marked clinical improvement was noted following treatment with rVIIa with significantly less transfusion, and obvious haemostasis associated with haemodynamic stability without adverse thrombotic complications.