Blood flow and the tractive force shear stress are important determinants of artery caliber, and reduced shear predisposes arteries to intimal thickening and atherosclerosis. The molecular basis for shear-induced changes in artery wall structure is poorly defined. A number of factors associated with normal and pathological artery wall remodeling are induced by shear stress in endothelial cell cultures. These include platelet-derived growth factor (PDGF), a potent mitogen, chemoattractant, and vasoconstrictor. To determine whether similar changes occur in vivo, we examined the effects of reduced blood flow on endothelial cell PDGF expression and proliferation in the rat carotid artery. Branches of the right internal and external carotid arteries were ligated, reducing common carotid artery blood flow from 8.0+/-0.6 to 0.5+/-0.1 mL/min while increasing flow in the left carotid from 7.1+/-0.6 to 10.8+/-0.7 mL/min. Shear stress following the procedure was 1.4+/-0.2 and 33.4+/-1.1 dyne/cm2 in carotids with reduced blood flow (RF) and increased blood flow (IF), respectively. Arteries were harvested 6, 24, 48, or 72 hours after ligation, perfusion-fixed, and opened longitudinally. Endothelial cell proliferation (bromodeoxyuridine [BrdU] labeling) was assessed en face at 24, 48, and 72 hours; expression of mRNA for PDGF-A and -B chains and PDGF alpha- and beta-receptors (in situ hybridization) was determined at 6, 48, and 72 hours after unilateral flow reduction. RF induced endothelial cell proliferation, which peaked at 48 hours (RF BrdU labeling: 24 hours, 0.4+/-0.2%; 48 hours, 7.2+/-2.0%; and 72 hours, 4.1+/-0.6%; n=5). PDGF-B expression increased in RF compared with IF endothelium within 48 hours and persisted at 72 hours (percent labeling [RF/IFx100]: 6 hours, 76+/-20%; 48 hours, 395+/-179%; and 72 hours, 208+/-44%; n=3). PDGF-A expression was similarly increased in RF endothelium. In contrast, expression of PDGF alpha- and beta-receptors was undetectable in RF and IF endothelium at all times. We conclude that endothelial cell PDGF ligand expression is induced by reduced shear stress in vivo and may play an important role in flow-mediated remodeling and atherogenesis.

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Restenosis after angioplasty has been attributed to intimal hyperplasia, equating loss of lumen caliber with neointimal mass. The data presented herein suggest that lumen narrowing after arterial wall injury may have little to do with intimal mass per se, but rather that a change in wall caliber or wall narrowing is the cause of restenosis.

Introduction: Physician burnout has been linked to medical errors, decreased patient satisfaction, and decreased career longevity. In light of the increasing prevalence of cardiovascular disease, vascular surgeon burnout presents a legitimate public health concern owing to the impact on the adequacy of the vascular surgery workforce. The aims of this study were to define the prevalence of burnout among practicing vascular surgeons and identify factors that contribute to burnout to facilitate future Society for Vascular Surgery (SVS) initiatives to mitigate this crisis.Methods: In 2018, active SVS members were surveyed electronically and confidentially using the Maslach Burnout Inventory. The survey was tailored to explore specialty-specific issues, and to capture demographic and practice-related characteristics. Emotional exhaustion (EE) and depersonalization (DP) were analyzed as dimensions of burnout. Consistent with convention, surgeons with a high score on the DP and/or EE subscales of the Maslach Burnout Inventory were considered to have at least one manifestation of professional burnout. Risk factors associated with symptoms of burnout were identified using bivariate analyses (c 2 , Kruskal-Wallis). Multivariate logistic regression models were developed to identify independent risk factors for burnout.Results: Of 2905 active SVS members, 960 responded to the survey (34% participation rate). After excluding retired surgeons and incomplete submissions, responses from 872 practicing vascular surgeons were analyzed. The mean age was 49.7 6 11.0 years; the majority of respondents (81%) were male. Primary practice settings were academic (40%), community practice (41%), veteran's hospital (3.3%), active military practice (1.5%), or other. Years in practice averaged 15.7 6 11.7. Overall, 41% of respondents had at least one symptoms of burnout (ie, high EE and/or high DP), 37% endorsed symptoms of depression in the past month, and 8% indicated they had considered suicide in the last 12 months. In unadjusted analysis, factors significantly associated with burnout (P < .05) included clinical work hours, on-call frequency, electronic medical record and documentation requirements, work-home conflict, and work-related physical pain. On multivariate analysis, age, work-related physical pain and work-home conflict were independent predictors for burnout.Conclusions: Symptoms of burnout and depression are common among vascular surgeons. Advancing age, work-related physical pain, and work-home conflict are independent predictors for burnout among vascular surgeons. Efforts to promote vascular surgeon well-being must address specialty-specific challenges, including the high prevalence of workhome conflict and occupational factors that contribute to work-related pain.