Ronald M. Fairman

Regulation of Notch1 and Dll4 by Vascular Endothelial Growth Factor in Arterial Endothelial Cells: Implications for Modulating Arteriogenesis and Angiogenesis

ABSTRACT Notch and its ligands play critical roles in cell fate determination. Expression of Notch and ligand in vascular endothelium and defects in vascular phenotypes of targeted mutants in the Notch pathway have suggested a critical role for Notch signaling in vasculogenesis and angiogenesis. However, the angiogenic signaling that controls Notch and ligand gene expression is unknown. We show here that vascular endothelial growth factor (VEGF) but not basic fibroblast growth factor can induce gene expression of Notch1 and its ligand, Delta-like 4 (Dll4), in human arterial endothelial cells. The VEGF-induced specific signaling is mediated through VEGF receptors 1 and 2 and is transmitted via the phosphatidylinositol 3-kinase/Akt pathway but is independent of mitogen-activated protein kinase and Src tyrosine kinase. Constitutive activation of Notch signaling stabilizes network formation of endothelial cells on Matrigel and enhances formation of vessel-like structures in a three-dimensional angiogenesis model, whereas blocking Notch signaling can partially inhibit network formation. This study provides the first evidence for regulation of Notch/Delta gene expression by an angiogenic growth factor and insight into the critical role of Notch signaling in arteriogenesis and angiogenesis.

Endovascular repair of traumatic thoracic aortic injury: Clinical practice guidelines of the Society for Vascular Surgery

The Society for Vascular Surgery® pursued development of clinical practice guidelines for the management of traumatic thoracic aortic injuries with thoracic endovascular aortic repair. In formulating clinical practice guidelines, the Society selected a panel of experts and conducted a systematic review and meta-analysis of the literature. They used the Grading of Recommendations Assessment, Development and Evaluation methods (GRADE) to develop and present their recommendations. The systematic review included 7768 patients from 139 studies. The mortality rate was significantly lower in patients who underwent endovascular repair, followed by open repair, and nonoperative management (9%, 19%, and 46%, respectively, P < .01). Based on the overall very low quality of evidence, the committee suggests that endovascular repair of thoracic aortic transection is associated with better survival and decreased risk of spinal cord ischemia, renal injury, graft, and systemic infections compared with open repair or nonoperative management (Grade 2, Level C). The committee was also surveyed on a variety of issues that were not specifically addressed by the meta-analysis. On these select matters, the majority opinions of the committee suggest urgent repair following stabilization of other injuries, observation of minimal aortic defects, selective (vs routine) revascularization in cases of left subclavian artery coverage, and that spinal drainage is not routinely required in these cases.

Pivotal results of the Medtronic Vascular Talent Thoracic Stent Graft System: the VALOR trial.

OBJECTIVE This report summarizes the 30-day and 12-month results of endovascular treatment using the Medtronic Vascular Talent Thoracic Stent Graft System (Medtronic Vascular, Santa Rosa, Calif) for patients with thoracic aortic aneurysms (TAA) who are considered candidates for open surgical repair. METHODS The study was a prospective, nonrandomized, multicenter, pivotal trial conducted at 38 sites. Enrollment occurred between December 2003 and June 2005. Standard follow-up interval examinations were prescribed at 1 month, 6 months, 1 year, and annually thereafter. These endovascular results were compared with retrospective open surgical data from three centers of excellence. RESULTS The Evaluation of the Medtronic Vascular Talent Thoracic Stent Graft System for the Treatment of Thoracic Aortic Aneurysms (VALOR) trial enrolled 195 patients, and 189 were identified as retrospective open surgical subjects. Compared with the open surgery group, the VALOR test group had similar age and sex distributions, but had a smaller TAA size. Patients received a mean number of 2.7 +/- 1.3 stent graft components. The diameters of 25% of the proximal stent graft components implanted were <26 mm or >40 mm. Left subclavian artery revascularization was performed before the initial stent graft procedure in 5.2% of patients. Iliac conduits were used in 21.1% of patients. In 33.5% of patients, the bare spring segment of the most proximally implanted device was in zones 1 or 2 of the aortic arch. In 194 patients (99.5%), vessel access and stent graft deployment were successful at the intended site. The 30-day VALOR results included perioperative mortality, 2.1%; major adverse advents, 41%; incidence of paraplegia, 1.5%; paraparesis, 7.2%; and stroke, 3.6%. The 12-month VALOR results included all-cause mortality, 16.1%; aneurysm-related mortality, 3.1%; conversion to open surgery, 0.5%; target aneurysm rupture, 0.5%; stent graft migration >10 mm, 3.9%; endoleak (12.2%), stent graft patency, 100%; stable or decreasing aneurysm diameter, 91.5%; and loss of stent graft integrity, four patients. No deployment-related events or perforation of the aorta by a graft component occurred. The Talent Thoracic Stent Graft showed statistically superior performance with respect to acute procedural outcomes (P < .001), 30-day major adverse events (41% vs 84.4%, P < .001), perioperative mortality (2% vs 8%, P < .01), and 12-month aneurysm-related mortality (3.1% vs 11.6%, P < .002) vs open surgery. CONCLUSIONS The pivotal VALOR 12-month trial results demonstrate that the Medtronic Talent Thoracic Stent Graft System is a safe and effective endovascular therapy as an alternative to open surgery in patients with TAA who were considered candidates for open surgical repair.

The CAPTURE registry: Results of carotid stenting with embolic protection in the post approval setting

Background: Pivotal study data examining carotid stenting with embolic protection as a less invasive alternative to endarterectomy for high surgical risk patients have been acquired under controlled conditions with highly selected physicians and hospitals. This report examines outcomes of carotid stenting post‐approval after diffusion of this technology to a broader cross‐section of physicians and hospitals. Methods: The Carotid Acculink/Accunet Post‐Approval Trial to Uncover Unanticipated or Rare Events (CAPTURE) is a prospective, multi‐center registry to assess two important aspects of the post‐IDE experience: the safety of carotid stenting by physicians with varying levels of experience as a measure of the adequacy of physician training, and the identification of rare/unexpected device‐related complications. The primary endpoint was a composite of death, any stroke, or myocardial infarction within 30 days post‐procedure. Results: 3,500 patients were enrolled by 353 physicians at 144 sites. The 30‐day primary endpoint event rate was 6.3% (95% CI: 5.5–7.1%) and did not differ among the three operator experience levels (5.3%, 6.0%, and 7.4%; P = 0.31) from most to least experienced, respectively. There were no differences in outcomes among physician specialties when adjusted for case mix. There were no unanticipated device related adverse events. Conclusions: The results of the CAPTURE study compare favorably to those achieved in the predicate pivotal investigations, and suggest that the post‐approval transfer of this new therapy to the community practice setting via carotid stent training programs is effective in preparing physicians with varying experience levels and specialty training backgrounds.

Bone Formation in Carotid Plaques A Clinicopathological Study

Background and Purpose— Bone formation and dystrophic calcification are present in carotid endarterectomy plaques. The clinical significance of these findings is unknown. The purpose of this study was to determine whether bone formation and extensive dystrophic calcification are associated with stable plaques and protective against ischemic vascular events. Methods— Carotid endarterectomy plaques were collected from 142 patients (94 men) with carotid stenosis. The specimens were evaluated for lamellar bone formation, dystrophic calcifications, inflammatory infiltrates, neovascularization, and histological type or grade of plaque according to a standard AHA grading system. Immunohistochemical staining was performed to identify vascular endothelial cells in neovascularization (factor VIII) and lymphocytes. Clinical data, including history of cerebrovascular and cardiovascular events, were recorded at the time of surgery. Results— Patients with calcification of carotid plaques had fewer symptoms of stroke and transient ischemic attack (P =0.042) than those without calcification. Stroke and transient ischemic attack occurred less frequently in patients with plaques with large calcific granules (P =0.021). Of the patients, 13% had lamellar bone formation, which directly correlated with the presence of sheetlike calcifications (P =0.0001) and inversely correlated with ulcerated lesions (P =0.048). The presence of bone also correlated with diabetes (P <0.01) and coronary artery disease (P <0.01). Of the 20 patients with bone, 6 had a history of stoke and transient ischemic attack (P =0.5). Conclusions— The results indicate that bone formation tends to occur in heavily calcified carotid lesions devoid of ulceration and hemorrhage. Patients with extensive calcification of the carotid plaques are less likely to have symptomatic disease.

The Society for Vascular Surgery Practice Guidelines: Management of the left subclavian artery with thoracic endovascular aortic repair

The Society for Vascular Surgery pursued development of clinical practice guidelines for the management of the left subclavian artery with thoracic endovascular aortic repair (TEVAR). In formulating clinical practice guidelines, the society selected a panel of experts and conducted a systematic review and meta-analysis of the literature. They used the grading of recommendations assessment, development, and evaluation (GRADE) method to develop and present their recommendations. The overall quality of evidence was very low. The committee issued three recommendations. Recommendation 1: In patients who need elective TEVAR where achievement of a proximal seal necessitates coverage of the left subclavian artery, we suggest routine preoperative revascularization, despite the very low-quality evidence (GRADE 2, level C). Recommendation 2: In selected patients who have an anatomy that compromises perfusion to critical organs, routine preoperative LSA revascularization is strongly recommended, despite the very low-quality evidence (GRADE 1, level C). Recommendation 3: In patients who need urgent TEVAR for life-threatening acute aortic syndromes where achievement of a proximal seal necessitates coverage of the left subclavian artery, we suggest that revascularization should be individualized and addressed expectantly on the basis of anatomy, urgency, and availability of surgical expertise (GRADE 2, level C).

The CAPTURE registry: Predictors of outcomes in carotid artery stenting with embolic protection for high surgical risk patients in the early post-approval setting

The use of carotid artery stenting with embolic protection has been practiced for over a decade in the United States, and increasingly so since carotid stenting received FDA approval in 2004. While there have been attempts at establishing predictors of outcomes in carotid artery stenting, they have generally been limited to single center experiences and/or multicenter retrospective surveys. This report examines predictors of outcomes in carotid stenting in the earliest and largest prospective multicenter neurologist‐adjudicated experience in the United States post device approval.

Results of a New Surgical Paradigm: Endovascular Repair for Acute Complicated Type B Aortic Dissection

BACKGROUND Conventional open repair of acute complicated type B aortic dissection is associated with significant morbidity and mortality. This study examined the results of thoracic endovascular aortic repair (TEVAR) in acute type B aortic dissection complicated with rupture or malperfusion syndrome. METHODS From 2004 through 2007, 35 patients (22 men) with acute complicated type B aortic dissection were treated with TEVAR. Indications included rupture in 18 (51.4%) and malperfusion syndrome in 17 (48.6%; mesenteric or renal, 5;lower extremities, 3; both, 9). Three types of endograft devices were used (mean per patient, 1.9 devices). Intravascular ultrasound imaging was used in 15 patients (42.8%). In patients with malperfusion syndrome, distal adjunct procedures to expand the true lumen included infrarenal aortic stents in 4, mesenteric/renal stents in 4, and iliofemoral stents in 7. Follow-up was 93.9% during a period of 18.3 months (range, 3 to 47 months). RESULTS The mean age was 58.6 +/- 13.4 years. Technical success (coverage of the primary tear site) was achieved in 34 patients (97.1%). Coverage of the left subclavian artery was required in 25 patients (71.4%). Thirty-day mortality was 2.8%. One-year survival was 93.4% +/- 4.6%. Complications included permanent renal failure (2.8%), stroke (2.8%), spinal cord ischemia (transient [5.7%], permanent [(2.8%]), and vascular access (14.2%). The mean intensive care unit and hospital stay were 4.7 +/- 2.6 and 16.7 +/- 12.0 days, respectively. CONCLUSIONS Endovascular repair of acute complicated type B aortic dissection is associated with low morbidity and mortality and has emerged as the surgical therapy of choice.

Platelet factor 4 localization in carotid atherosclerotic plaques: correlation with clinical parameters

Emerging evidence supports a role for platelets in the progression of atherosclerosis in addition to an involvement in thrombotic vascular occlusion. Platelet Factor 4 (PF4), a chemokine released by activated platelets, stimulates several pro-atherogenic processes. Therefore, we examined the localization of PF4 and the homologous protein, Neutrophil Activating Protein-2 (NAP-2) in lesions representing the evolution of human atherosclerotic plaques. Carotid plaques from 132 patients with critical carotid stenosis and 6 autopsy specimens were studied. Clinical, histologic and immunohistochemical data were analyzed using a chi(2)-test. PF4 was detected in the cytoplasm of luminal and neovascular endothelium, in macrophages and in regions of plaque calcification. The presence of PF4 in macrophages and neovascular endothelium correlated with lesion grade (p = 0.004; p = 0.044). Staining of macrophages for PF4 correlated with the presence of symptomatic atherosclerotic disease (p = 0.028). In early lesions, PF4 was commonly found in macrophages of early lesions (Grade I/II), whereas NAP-2 was rarely present. In conclusion, correlation between PF4 deposition, lesion severity and symptomatic atherosclerosis suggests that persistent platelet activation may contribute to the evolution of atherosclerotic vascular lesions. These studies support the rationale for the chronic use of anti-platelet therapy in patients at risk for developing symptomatic atherosclerosis.

The effect of left subclavian artery coverage on morbidity and mortality in patients undergoing endovascular thoracic aortic interventions: A systematic review and meta-analysis

OBJECTIVES Thoracic endografts (stent grafts) have emerged as a less invasive modality to treat various thoracic aortic lesions. The intentional coverage of the left subclavian artery (LSA) during the placement of these endografts is associated with several complications including stroke, spinal cord ischemia, and arm ischemia. In this review, we synthesize the available evidence regarding the complications associated with LSA coverage. METHODS We searched electronic databases (MEDLINE and EMBASE) from January 1990 through February 2008 for studies that included patients who received thoracic endografts and had intentional LSA coverage. Eligible studies had a control group that either received the endograft without LSA coverage or had primary revascularization prior to coverage. Two independent reviewers determined trial eligibility and extracted descriptive, methodological and outcome data from each eligible study. Meta-analyses estimated Peto odds ratio (OR) and 95% confidence intervals (CI) to describe the strength of association between coverage and complications; the I(2) statistic described the proportion of inconsistency of treatment effect among studies not due to chance. RESULTS We found 51 eligible observational studies. LSA coverage was associated with significant increase in the risk of arm ischemia (OR 47.7; CI, 9.9-229.3; I(2) = 72%, 19 studies) and vertebrobasilar ischemia (OR 10.8; CI, 3.17-36.7; I(2) = 0%; eight studies); and nonsignificant increase in the risk of spinal cord ischemia (OR 2.69; CI, 0.75-9.68; I(2) = 40%; eight studies) and anterior circulation stroke (OR 2.58; CI, 0.82-8.09; I(2) = 64%, 13 studies). There were no significant associations between LSA coverage and death, myocardial infarction, or transient ischemic attacks. The incidence of phrenic nerve injury as a complication of primary revascularization was 4.40% (CI, 1.60%-12.20%). Data on perioperative infection were sparse and rarely reported. CONCLUSIONS Very low quality evidence suggests that LSA coverage increases the risk of arm ischemia, vertebrobasilar ischemia, and possibly spinal cord ischemia and anterior circulation stroke.