Anti-phosphorylcholine IgM, an Anti-inflammatory Mediator, Predicts Peripheral Vein Graft Failure: A Prospective Observational Study.

OBJECTIVES: One third of infrainguinal vein bypasses may fail within the first 1.5 years. Pro- and anti-inflammatory mechanisms are thought to be involved in these graft stenoses and occlusions. In previous studies, low levels of anti-phosphorylcholine IgM (anti-PC IgM, an innate anti-inflammatory IgM) have been associated with increased cardiovascular events. In this study, the peri-operative dynamics of anti-PC IgM levels were established during leg bypass surgery, and associations assessed between anti-PC IgM levels and primary graft patency. DESIGN AND METHODS: This was a prospective, observational cohort study of infrainguinal autogenous vein bypass for peripheral arterial occlusive disease involving four university affiliated hospitals. Plasma cytokine and anti-PC IgM levels were measured pre- and post-operatively. The outcome of interest was loss of primary graft patency because of occlusion or intervention for graft stenosis. RESULTS: One hundred and forty-two consecutive patients were enrolled: mean age 66 (46-91); 91% white race and male; 72.5% critical limb ischaemia (Fontaine III or IV). Median pre-operative anti-PC IgM levels were 49 units/mL (IQR 32.3-107.7, mean 89.8 + 101 sd). During follow up of an average of 1.8 years (1 month-7.4 years), 50 (35.2%) grafts lost primary patency. Pre-operative levels of interleukin 6 or C-reactive protein did not predict graft failure. Patients with pre-operative anti-PC IgM values in the lowest quartile had a twofold increased risk of graft failure (multivariable Cox proportional hazard, p = .03, HR 2.11, 95% CI 1.09-4.07), even after accounting for the other significant factors of conduit diameter, distal anastomosis, smoking, and the severity of leg ischaemia. CONCLUSIONS: Low levels of anti-PC IgM are associated with vein bypass graft failure. This biological mediator may be a useful marker to identify patients at higher risk, and offers the potential for novel, directed therapies for vascular inflammation and its consequences.

Tissue Factor Activity in Dialysis Access Grafts.

BACKGROUND: Intimal hyperplasia at the venous anastomosis of dialysis grafts causes early failure. We developed a sheep model of arteriovenous prosthetic grafts that fail rapidly due to intimal hyperplasia with histologic features nearly identical to human access grafts. A prominent feature of lesion development in this model is formation of luminal thrombus that becomes organized into stenosing lesions by macrophage and myofibroblast infiltration. To better understand this process, we examined the presence and activity of tissue factor (TF) in this system. This protein is the physiological initiator of coagulation in vivo and is known to contribute to development of intimal hyperplasia after vascular injury. METHODS: Expanded polytetrafluorethylene (ePTFE) grafts were placed between the carotid artery and external jugular vein in sheep. Grafts were examined for luminal TF activity using a novel ex vivo assay. In a separate series of grafts, immunohistochemistry was used to localize smooth muscle cells, monocytes, and TF protein. RESULTS: At 2 days, luminal TF activity already was higher in the venous and arterial end of the graft than in the adventitia. This high level of activity persisted at 8 weeks. TF activity was higher in the venous end of the grafts than in the arterial end at 2 and 8 weeks (40% and 47% increase, n = 5, n = 3, respectively, P < 0.05). Immunohistochemistry revealed TF protein localized in regions with or adjacent to fibrin accumulation and often in regions close to the lumen. CONCLUSIONS: This study further examines the development of intimal hyperplasia in ePTFE dialysis access grafts. In this model, TF levels on the luminal surface were increased throughout the arteriovenous grafts and the adjacent vessels as early as 2 days after engraftment and for as long as 8 weeks thereafter. The highest levels of activity were found in the venous end of the graft, where hyperplasia is most robust. Increased activity of TF is associated with luminal thrombus, which provides a scaffolding for development of intimal hyperplasia. These findings present an opportunity to develop strategies to limit TF activity within the graft. Further studies using agents delivered locally or incorporated into the graft matrix to block the luminal activity of TF are warranted.

Low levels of a natural IgM antibody are associated with vein graft stenosis and failure.

BACKGROUND: All humans have natural, protective antibodies directed against phosphorylcholine (PC) epitopes, a common inflammatory danger signal appearing at sites of cell injury, oxidative stress, and on bacterial capsules. In large human cohorts, low levels of anti-PC IgM were associated with a significantly increased risk of stroke or myocardial infarction. However, it is not known if these antibodies protect against the premature closure of arterial reconstructions. METHODS: A prospective, observational study of patients undergoing elective, infrainguinal, autogenous vein bypasses for atherosclerotic occlusive disease of the legs was conducted. Clinical data were recorded prospectively, and preoperative levels of anti-PC IgM measured with the CVDefine kit from Athera Biotechnologies (Solna, Sweden). The principal clinical end point was the loss of primary patency (loss of graft flow, or any intervention for stenosis). Patients were followed regularly by duplex ultrasound at 1, 3, 6, 12, 18 months, and yearly thereafter. RESULTS: Fifty-six patients were studied, for an average of 1.3 years. Indications for surgery were claudication (33.9%), ischemic rest pain (17.9%), and ischemia with ulceration or gangrene (48.2%). Seventeen (30.4%) patients experienced loss of primary patency (10 graft occlusions, seven surgical or endovascular revisions of graft stenoses). Kaplan-Meier survival analysis showed that the quartile of patients with the lowest anti-PC IgM levels had significantly worse primary graft patency (log-rank test, P = .0085). Uni- and multivariate Cox proportional hazards analysis revealed that the preoperative anti-PC IgM level was an important predictor of graft failure. Patients with IgM values in the lowest quartile had a 3.6-fold increased risk of graft failure (95% confidence interval: 1.1-12.1), even after accounting for other significant clinical or technical factors such as indication for surgery, site of distal anastomosis, or vein graft diameter. CONCLUSIONS: A naturally occurring IgM antibody directed against the proinflammatory epitope PC may be protective against vein graft stenosis and failure, through anti-inflammatory mechanisms. Measurement of this antibody may be a useful prognostic indicator, although larger studies of more diverse populations will be needed to confirm these results. The biological actions of anti-PC IgM suggest it may be useful in developing immunotherapies to improve bypass longevity.

Favorable discharge disposition and survival after successful endovascular repair of ruptured abdominal aortic aneurysm.

OBJECTIVE: Endovascular repair of ruptured abdominal aortic aneurysm (rEVAR) has been shown to improve perioperative outcomes compared with open surgical repair (OSR). Follow-up of these patients, however, is lacking. In this study, we compare the discharge disposition and midterm survival of ruptured aneurysm patients who survived treatment with either rEVAR or OSR. METHODS: We performed an institutional review board-approved, single-institution, retrospective review of all patients with ruptured abdominal aortic aneurysms (rAAAs) admitted from July 2007 to February 2012. Primary outcomes were discharge disposition and midterm survival (>30 days after the index operation). We also evaluated compliance with follow-up and prevalence of endoleak. RESULTS: A total of 118 patients were analyzed. Eight patients received only comfort care, 10 died in the operating room, 39 underwent OSR, and 61 had rEVAR. Average age and sex were similar (OSR, 77 ± 7.8 years, 85% male; rEVAR, 74 ± 7.4 years, 79% male). Seventy-two survived to discharge (54% OSR [21/39]; 84% rEVAR [51/61]; P = .001). OSR patients had longer lengths of intensive care unit and total length of stay than rEVAR (11.8 ± 10.4/23 ± 16.4 days vs 6.3 ± 8.5/12.3 ± 13.0 days; P = .002/.02). Only 19% (4/21) of patients were discharged home after OSR, rather than to a skilled nursing facility. Significantly more rEVAR patients were discharged to home rather than a skilled nursing facility (65%; 33/51) (P = .0004). Overall, the follow-up rate for determination of survival for patients who lived past 30 days was 86% (56/65; median, 14 months; 25th-75th interquartile, 3.1-27.8). Multivariable logistic regression revealed only the type of procedure performed and perioperative hypotension predicted discharge destination. Kaplan-Meier analysis revealed a significant midterm survival benefit for patients after rEVAR compared with OSR (P = .01, log-rank). Subgroup analysis of survivors past 30 days revealed similar rates of midterm survival (P = .7, log-rank). Overall, midterm relative risk reduction for death after rEVAR vs OSR was 35% (95% confidence interval, 0.06-0.59). CONCLUSIONS: We have previously demonstrated that successful utilization of rEVAR improves the early survival of rAAA patients compared with OSR. This study shows that more patients are able to be discharged to home after rEVAR and that the early survival advantage is continued in midterm follow-up, suggesting that rEVAR should be attempted first when feasible. Further studies are needed to determine the long-term durability of endovascular repair in the management of rAAA as well as the impact on cost and long-term quality of life.

Mycotic aortic aneurysm caused by haemophilus influenzae group F.

BACKGROUND: Haemophilus influenzae is a rare cause of mycotic aortic aneurysm. We present a case of H. influenzae mycotic aortic aneurysm, which was complicated by prior endovascular stent-graft placement at another facility. METHODS: A 58 year-old man was treated by endograft placement for a presumed penetrating aortic ulcer after having symptoms of abdominal pain and malaise for one month. He presented to our institution 11 days after endograft placement with septic physiology. Repeat computed tomography angiogram demonstrated an inflammatory mass around the distal aorta and right common iliac artery, which had an associated contained rupture. RESULTS: The patient was treated using intravenous antibiotics, axillo-bifemoral bypass followed by endograft explantation and aortic and iliac ligation. Intraoperative cultures grew Haemophilus influenzae, serotype f. CONCLUSIONS: Aortic endografts have been successfully used for treatment of selected mycotic aneurysms, generally after adequate treatment of the primary infection with intravenous antibiotics. This case demonstrates the unfavorable natural history of endograft placement in an unsuspected mycotic aneurysm. A high index of suspicion for possible aortic infection should be maintained for patients with systemic symptoms and unusual aortic pathology prior to choosing endovascular repair.

Three-dimensional ultrasonography measurements after endovascular aneurysm repair.

BACKGROUND: Ultrasonographic (US) assessment of abdominal aortic aneurysms is typically performed by measuring maximal aneurysm diameter from two-dimensional images. These measurements are prone to inaccuracies owing to image planes and interobserver variability. The purpose of this study was to compare the variability in diameter, cross-sectional area (CSA), and volume measurements of abdominal aortic aneurysms obtained using a three-dimensional (3D) US imaging system with those obtained using computed tomographic (CT) angiography, and to determine the reliability of these measures. METHODS: Seven patients in whom endovascular aneurysm repairs were performed underwent CT angiography in addition to a 3D US scan. Measurements computed using 3D surface reconstructions of CT and 3D US scans included maximum diameter, CSA, and aneurysm volume. The seven matched CT and 3D US scans were compared at baseline and 6 to 8 weeks later. RESULTS: The average aneurysm measured 57.2 mm on CT and 56.2 mm on US (P = 0.14). Correlation coefficients for diameter, CSA, and volume were 0.88, 0.90, and 0.93, respectively (all P values < 0.001). A Bland-Altman analysis demonstrated a strong agreement between 92% of the diameter, 96.4% of the CSA, and 100% of the volume measurements. The interrater reliability was remarkably high comparing the modalities (CT vs. US), and ranged from 0.934 to 0.997 for single measurements and 0.965 to 0.998 for all measurements together; moreover, there was a strong reliability when the tests were reviewed 6 to 8 weeks later, with a reliability of 0.962 to 0.998 for single measurements and 0.992 to 0.999 for all tests (all P values < 0.001). CONCLUSIONS: The 3D US is an accurate and noninvasive method of determining aneurysm size and geometry that is reproducible. Volumetric measurements may represent a significant advancement in long-term follow-up after endovascular aneurysm repair.

Enhancement of capillary and cellular ingrowth in ePTFE implants with a proangiogenic recombinant construct derived from fibronectin.

Based on our discoveries of a unique, synergistic interplay between vascular endothelial growth factor (VEGF) and specific domains of the matrix protein fibronectin (FN), we used recombinant technology to create a new protein construct derived from the cell-binding and VEGF-binding domains of FN. We wished to test the hypothesis that this prototype recombinant FN (rFN) protein would enhance cellular and capillary ingrowth in vivo into expanded polytetrafluoroethylene (ePTFE) implants. ePTFE disks of high porosity (60 micron internodal distance) were embedded with fibrin gel and heparin, with/without mixtures of VEGF and rFN and were implanted subcutaneously in rats. Control implants embedded with fibrin glue and heparin alone showed an average of 8.5% (±0.51% standard error mean (SEM)) cellular ingrowth. The addition of either VEGF or rFN caused a modest but significant increase in cellular ingrowth (12.7 ± 1% and 11.8 ± 0.98%, respectively, p < 0.004). However, the combination of rFN/VEGF/heparin dramatically increased cellular ingrowth (27.6 ± 1.62%, p < 0.001), compared with all other treatments. Quantification of capillary ingrowth yielded the same pattern. These results suggest that the incorporation of such biological modulators into cardiovascular implants could offer new strategies for the design of a ready-made small diameter prosthetic graft with enhanced capacity for neovascularization and endothelialization.

Outcomes following endovascular vs open repair of abdominal aortic aneurysm: a randomized trial.

CONTEXT: Limited data are available to assess whether endovascular repair of abdominal aortic aneurysm (AAA) improves short-term outcomes compared with traditional open repair. OBJECTIVE: To compare postoperative outcomes up to 2 years after endovascular or open repair of AAA in a planned interim report of a 9-year trial. DESIGN, SETTING, AND PATIENTS: A randomized, multicenter clinical trial of 881 veterans (aged > or = 49 years) from 42 Veterans Affairs Medical Centers with eligible AAA who were candidates for both elective endovascular repair and open repair of AAA. The trial is ongoing and this report describes the period between October 15, 2002, and October 15, 2008. INTERVENTION: Elective endovascular (n = 444) or open (n = 437) repair of AAA. MAIN OUTCOME MEASURES: Procedure failure, secondary therapeutic procedures, length of stay, quality of life, erectile dysfunction, major morbidity, and mortality. RESULTS: Mean follow-up was 1.8 years. Perioperative mortality (30 days or inpatient) was lower for endovascular repair (0.5% vs 3.0%; P = .004), but there was no significant difference in mortality at 2 years (7.0% vs 9.8%, P = .13). Patients in the endovascular repair group had reduced median procedure time (2.9 vs 3.7 hours), blood loss (200 vs 1000 mL), transfusion requirement (0 vs 1.0 units), duration of mechanical ventilation (3.6 vs 5.0 hours), hospital stay (3 vs 7 days), and intensive care unit stay (1 vs 4 days), but required substantial exposure to fluoroscopy and contrast. There were no differences between the 2 groups in major morbidity, procedure failure, secondary therapeutic procedures, aneurysm-related hospitalizations, health-related quality of life, or erectile function. CONCLUSIONS: In this report of short-term outcomes after elective AAA repair, perioperative mortality was low for both procedures and lower for endovascular than open repair. The early advantage of endovascular repair was not offset by increased morbidity or mortality in the first 2 years after repair. Longer-term outcome data are needed to fully assess the relative merits of the 2 procedures. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00094575.

Proliferative capacity of vein graft smooth muscle cells and fibroblasts in vitro correlates with graft stenosis.

OBJECTIVE: About a quarter of peripheral vein grafts fail due in part to intimal hyperplasia. The proliferative capacity and response to growth inhibitors of medial smooth muscle cells and adventitial fibroblasts in vitro were studied to test the hypothesis that intrinsic differences in cells of vein grafts are associated with graft failure. METHODS: Cells were grown from explants of the medial and adventitial layers of samples of vein grafts obtained at the time of implantation. Vein graft patency and function were monitored over the first 12 months using ankle pressures and Duplex ultrasound to determine vein graft status. Cells were obtained from veins from 11 patients whose grafts remained patent (non-stenotic) and from seven patients whose grafts developed stenosis. Smooth muscle cells (SMCs) derived from media and fibroblasts derived from adventitia were growth arrested in serum-free medium and then stimulated with 1 muM sphingosine-1-phosphate (S1P), 10 nM thrombin, 10 ng/ml epidermal growth factor (EGF), 10 ng/ml platelet-derived growth factor-BB (PDGF-BB), PDGF-BB plus S1P, or PDGF-BB plus thrombin for determination of incorporation of [(3)H]-thymidine into DNA. Cells receiving PDGF-BB or thrombin were also treated with or without 100 microg/ml heparin, which is a growth inhibitor. Cells receiving thrombin were also treated with or without 150 nM AG1478, an EGF receptor kinase inhibitor. RESULTS: SMCs and fibroblasts from veins of patients that developed stenosis responded more to the growth factors, such as PDGF-BB alone or in combination with thrombin or S1P, than cells from veins of patients that remained patent (P = .012). In addition, while PDGF-BB-mediated proliferation of fibroblasts from grafts that remained patent was inhibited by heparin (P < .03), PDGF-BB-mediated proliferation of fibroblasts from veins that developed stenosis was not (P > .5). CONCLUSION: Inherent differences in the proliferative response of vein graft cells to PDGF-BB and heparin may explain, in part, the variability among patients regarding long term patency of vein grafts.

Inhibition of neointimal hyperplasia in a sheep model of dialysis access failure with the bioabsorbable Vascular Wrap paclitaxel-eluting mesh.

OBJECTIVE: This study evaluated the effect of a bioabsorbable mesh containing paclitaxel on neointimal hyperplasia in a sheep model of dialysis access failure. METHODS: Forty neutered male sheep were randomized to one of five parallel groups: no mesh; or a 3-cm x 6-cm mesh with 0.0, 0.3, 0.7, or 1.2 microg/mm(2) of paclitaxel for a total dose of 0.0, 0.6, 1.3, or 2.2 mg, respectively. Commercially available 6-mm internal diameter expanded polytetrafluoroethylene grafts were surgically placed between the left common carotid artery and the right external jugular vein. For those animals randomized to one of the mesh groups, the mesh was placed around the distal end of the graft and venous anastomosis. Patency was assessed at weekly intervals throughout the study. Animals were euthanized 8 weeks after implantation, and grafts and veins were harvested. After histologic processing, six cross sections were cut at the venous end of the graft and vessel. The primary and secondary efficacy outcome measures, respectively, were the area and capillary density of the neointima at the graft-vein anastomosis. Histologic analyses were also performed to investigate the effects of the paclitaxel-eluting mesh on the anastomotic site. RESULTS: Grafts occluded before the scheduled sacrifice in five animals, and they were excluded from the study and not replaced. Control animals developed significant neointimal hyperplasia at the cross section taken perpendicular to the graft at its most distal end: the neointimal area measured 10.5 +/- 6.8 mm(2) in the no mesh group and 6.4 +/- 3.2 mm(2) in the zero-dose mesh group (P = .28). In contrast, neointimal area was significantly reduced in the paclitaxel mesh groups: 0.9 +/- 1.4 mm(2) in the 0.3 microg/mm(2) group (P = .008 vs zero-dose mesh), 1.3 +/- 1.5 mm(2) in the 0.7 microg/mm(2) group (P = .004 vs zero-dose mesh), and 1.2 +/- 1.4 mm(2) in the 1.2 microg/mm(2) group (P = .008 vs zero-dose mesh). Capillary density in the neointima at the graft-vein anastomosis decreased with paclitaxel and was significantly reduced in the paclitaxel mesh groups with 0.3 and 1.2 mug/mm(2) compared with the zero-dose mesh control (3.6 +/- 2.9 vs 8.9 +/- 5.6 per mm(2) [P = .022] and 1.1 +/- 1.7 vs 8.9 +/- 5.6 per mm(2) [P = .001] respectively). The paclitaxel mesh had no significant effect on healing of the anastomosis or on the thickness of the adjacent vein. CONCLUSIONS: In this model, the paclitaxel-eluting mesh significantly reduced neointimal hyperplasia and neointimal capillary density without apparent toxicity to the adjacent vein.

Very late survival after vascular surgery.

PURPOSE: The aim of this study was to define very late survival in veterans who routinely underwent preoperative assessment of left ventricular function using radionuclide ventriculography (RNVG) before elective major vascular surgery from 7/84 to 7/88 at one Veterans Affairs Medical Center. METHODS: RNVG defined left ventricular ejection fraction (EF) and determined the presence of ventricular wall motion abnormalities. Patients undergoing elective vascular surgery (n = 310) who had preoperative RNVG were then followed over the years using direct contact, VA administrative databases, and, most recently, the Social Security Death Index. RESULTS: Follow-up was 6.64 +/- 4.62 years (range 0 to 16.2 years). Current survival is 10% (11/107) after carotid surgery, 12% (10/82) after aortic aneurysm repair, 15% (17/111) after extremity reconstruction, and 0% (0/10) after visceral artery reconstruction (ns). There was no statistically significant difference in mortality between the different types of vascular surgery at 30 days or at 1, 5, and 10 years after surgery (ns). Actual survival rates at 5 years after carotid surgery, aneurysm repair, extremity reconstruction, and visceral reconstruction were 55, 61, 59, and 50%, respectively. Stepwise logistic regression analysis was performed which included preoperatively defined cardiovascular risk factors, type of surgery, and results of RNVG. The final regression model indicated that age, diabetes, smoking at the time of surgery, and low EF were independently associated with overall mortality while angina, prior myocardial infarction (MI), and type of operation were not. Mean survival duration with normal EF (>50%) was 7.99 years versus 4.78 years with low EF (P < 0.001). No patient with severe left ventricular dysfunction (EF < or = 35%; n = 39) or who had postoperative cardiac complications (MI, CHF, ventricular arrhythmia; n = 38) survived to the present. CONCLUSIONS: Very late survival after major vascular surgery was related to the presence of diabetes, active smoking at the time of surgery, left ventricular function, and postoperative cardiac complications. Since there was no association of overall mortality with angina or prior MI, an aggressive approach to coronary evaluation in such patients might not alter very late survival.