Effects of exercise on gene expression in human peripheral blood mononuclear cells

Exercise leads to increases in circulating levels of peripheral blood mononuclear cells (PBMCs) and to a simultaneous, seemingly paradoxical increase in both pro- and anti-inflammatory mediators. Whether this is paralleled by changes in gene expression within the circulating population of PBMCs is not fully understood. Fifteen healthy men (18–30 yr old) performed 30 min of constant work rate cycle ergometry (∼80% peak O2 uptake). Blood samples were obtained preexercise (Pre), end-exercise (End-Ex), and 60 min into recovery (Recovery), and gene expression was measured using microarray analysis (Affymetrix GeneChips). Significant differential gene expression was defined with a posterior probability of differential expression of 0.99 and a Bayesian P value of 0.005. Significant changes were observed from Pre to End-Ex in 311 genes, from End-Ex to Recovery in 552 genes, and from Pre to Recovery in 293 genes. Pre to End-Ex upregulation of PBMC genes related to stress and inflammation [e.g., heat shock protein 70 (3.70-fold) and dual-specificity phosphatase-1 (4.45-fold)] was followed by a return of these genes to baseline by Recovery. The gene for interleukin-1 receptor antagonist (an anti-inflammatory mediator) increased between End-Ex and Recovery (1.52-fold). Chemokine genes associated with inflammatory diseases [macrophage inflammatory protein-1α (1.84-fold) and -1β (2.88-fold), and regulation-on-activation, normal T cell expressed and secreted (1.34-fold)] were upregulated but returned to baseline by Recovery. Exercise also upregulated growth and repair genes such as epiregulin (3.50-fold), platelet-derived growth factor (1.55-fold), and hypoxia-inducible factor-I (2.40-fold). A single bout of heavy exercise substantially alters PBMC gene expression characterized in many cases by a brisk activation and deactivation of genes associated with stress, inflammation, and tissue repair.

Negative energy balance plays a major role in the IGF-I response to exercise training

Circulating IGF-I is correlated with fitness, but results of prospective exercise training studies have been inconsistent, showing both increases and decreases in IGF-I. We hypothesized that energy balance, often not accounted for, is a regulating variable such that training plus an energy intake deficit would cause a reduction in IGF-I, whereas training plus energy intake excess would lead to an increased IGF-I. To test this, 19 young, healthy men completed a 7-day strenuous exercise program in which they were randomly assigned to either a positive energy balance [overfed (OF), n = 10] or negative energy balance [underfed (UF), n = 9] group. IGF-I (free and total), insulin, and IGF-binding protein-1 were measured before, during, and 1 wk after the training. Weight decreased in the UF subjects and increased in the OF subjects. Free and total IGF-I decreased substantially in the UF group (P < 0.0005 for both), but, in the OF group, IGF-I remained unchanged. The UF group also demonstrated an increase in IGF-binding protein-1 (P < 0.027), whereas glucose levels decreased (P < 0.0005). In contrast, insulin was reduced in both the OF and UF exercise-training groups (P < 0.044). Finally, within 7 days of the cessation of the diet and training regimen, IGF-I and IGF-binding protein-1 in the UF group returned to preintervention levels. We conclude that energy balance during periods of exercise training influences circulating IGF-I and related growth mediators. Exercise-associated mechanisms may inhibit increases in IGF-I early in the course of a training protocol, even in overfed subjects.

Assessing the Perioperative Safety of Common Femoral Endarterectomy in the Endovascular Era

Introduction:

Common femoral endarterectomy (CFE) has historically been the preferred treatment for atherosclerotic lesions involving the common femoral artery. The objectives of this study are to delineate the safety of this open procedure in the endovascular era, establish contemporary benchmarks for morbidity and mortality after CFE, and identify the subgroup of patients at increased risk of postoperative adverse events.

Methods:

Patients undergoing elective CFE in the 2007 to 2010 National Surgical Quality Improvement Project database were examined. Univariate analyses were used to identify the factors associated with major morbidity and mortality. Significant variables by univariate analysis were used to create multivariate logistic regression models for morbidity and mortality.

Results:

A total of 1513 patients underwent elective CFE. The 30-day mortality rate was 1.5%. Postoperative morbidities included cardiac (1.0%), pulmonary (1.9%), renal (0.4%), urinary tract infection (1.7%), thromboembolic (0.5%), neurologic (0.4%), sepsis (2.7%), superficial (6.3%), and deep surgical site complications (2.0%). At least 1 complication, including major and minor, was seen in 7.9% of the patients. By multivariate analysis, partial- and total-dependent functional status (odds ratio [OR] 9.0, 95% confidence interval [CI] 2.8-28.4 and OR 21.3, 95% CI 3.3-139.4) and dyspnea at rest (OR 8.2, 95% 1.2-58.8) predicted mortality. Independent predictors of morbidity include steroid use (OR 2.4, 95% 1.4-4.1), diabetes (OR 1.8, 95% CI 1.3-2.4), and obesity (OR 1.6, 95% CI 1.1-2.4).

Discussion:

Overall, CFE is tolerated well by the majority of patients with peripheral arterial disease. These results affirm the safety of CFE and can still be used as standard first-line therapy in most patients. Long-term results for endovascular interventions need to be studied to see whether high-risk patients that we identified for CFE would benefit more from an endovascular approach.

Risk factors for protracted postoperative length of stay after lower extremity bypass for critical limb ischemia

BACKGROUND

Compared with other common chronic conditions, admissions for management of peripheral arterial disease (PAD) are associated with prolonged hospitalizations. Length of stay (LOS) is one of many metrics receiving increased attention in the current focus on efficient healthcare delivery. Our objective was to characterize LOS among patients with severe PAD, those undergoing surgical bypass for critical limb ischemia (CLI), and identify risk factors for protracted postoperative LOS.

METHODS

Patient data from the 2007 to 2009 American College of Surgeons National Surgical Quality Improvement Program were used to develop a database consisting of patients undergoing bypass surgery for CLI (n = 4,894). Protracted postoperative LOS was defined as the top quartile of days hospitalized from surgery to discharge. Preoperative risk factors with significant association (Pearson chi-squared test; P < 0.05) were used to develop a logistic regression model for protracted postoperative LOS.

RESULTS

Average postoperative LOS was 7.5 days (median 6 days). The top quartile of postoperative LOS, >8 days, was used to define protracted LOS. Independent preoperative risk factors for protracted postoperative LOS included demographic characteristics (advanced age and non-Caucasian race), comorbidities, and medical history (e.g., obesity, dialysis dependence, severe cardiac and pulmonary disease, and bleeding disorders). Indicators of PAD severity (e.g., distal target sites, open wounds or gangrene, and prior arterial surgery) were also independent predictors of protracted LOS after surgery. The greatest predictors of extended postoperative LOS were prolonged preoperative hospitalization (OR 2.2 [95% CI: 1.8-2.6], P < 0.001) and preoperative dependent functional status (OR 2.0 [95% CI: 1.7-2.3], P < 0.001 for partial dependence; OR 2.8 [95% CI: 1.8-4.3], P < 0.001 for totally dependent status), where OR and CI stand for odds ratio and confidence interval.

CONCLUSIONS

Here, we identify preoperative risk factors for protracted postoperative LOS after infrainguinal bypass for CLI. These findings provide an important evidence basis for ongoing efforts to reduce healthcare spending and facilitate provision of efficient health care. Future efforts will include prospective identification of patients at high risk for protracted postoperative LOS and targeted multidisciplinary efforts to reduce associated costs without sacrificing healthcare quality.

Characterizing the evolution of perioperative outcomes and costs of endovascular abdominal aortic aneurysm repair

OBJECTIVE

The purpose of this study is to characterize the evolution in perioperative outcomes and costs of endovascular abdominal aortic aneurysm (AAA) repair (EVAR) by detailing changes in adjusted outcomes and costs over time.

METHODS

National Inpatient Sample (2000-2011) data were used to evaluate patient characteristics, outcomes, and perioperative costs for elective EVAR performed for intact AAA. Outcomes were adjusted for patient demographics and comorbidities, and hospital factors by multivariate analysis. Costs were calculated from hospital cost to charge ratio files and adjusted to 2011 dollars.

RESULTS

From 2000 to 2011, 185,249 patients underwent elective EVAR for intact AAA. The absolute rates of in-hospital major morbidity, mortality, and procedural costs all decreased significantly over time (P < .0001). The prevalence of major comorbidities in patients undergoing EVAR, including obesity, diabetes, and dyslipidemia, all increased significantly over time. After adjusting for multiple demographics, comorbidities, and hospital-level factors, recent outcomes of EVAR (2009-2011) remain superior to the early experience (2000-2002) with respect to mortality and major complications.

CONCLUSIONS

From 2000-2011, the perioperative outcomes of EVAR improved significantly despite a higher prevalence of comorbidities among patients undergoing repair. Concurrently, procedure-associated costs declined. Advanced technology is often implicated in escalating healthcare spending, and the value of novel techniques is often questioned. These findings highlight that, in the case of EVAR, procedural outcomes have improved while the initial costs of repair have declined over time. EVAR offers an interesting example for stakeholders to consider in the era of cost-containment pressures and criticism of nascent, expensive technology in healthcare.

Risk factors of nonretrieval of retrievable inferior vena cava filters

BACKGROUND

Optimal use of retrievable inferior vena cava (IVC) filters is an important health care issue, and despite an exponential rise in the use of retrievable IVC filters, national trends suggest that most of these filters are not removed. The purpose of this study was to identify risk factors associated with nonretrieval of retrievable IVC filters at our institution.

METHODS

A retrospective institutional review of all patients undergoing IVC filter placement from June 2010 to June 2012 was performed. A number of patient parameters were studied, including relevant demographics, indication for filter placement, clinical history, related hospitalization, and whether filter retrieval was performed. Patient parameters were compared by univariate and multivariate logistic regression analyses.

RESULTS

There were 605 retrievable IVC filters placed over a 24-month period by vascular surgery, intervention radiology, and interventional cardiology. The follow-up retrieval rate was 25%. By indication, 272 (45%), 53 (9%), and 280 (46%) filters were placed for absolute, relative, and prophylactic indications, respectively. Independent predictors for nonretrieval by multivariate analysis were age >80 years (hazard ratio [HR], 5.0; 95% confidence interval [CI], 1.7-20; P < 0.001), acute bleed (HR, 2.5; 95% CI, 1.4-5; P < 0.001), current malignancy (HR, 2.0; 95% CI, 1.3-3.3; P = 0.011), postfilter anticoagulation (HR, 0.5; 95% CI, 0.28-0.9; P = 0.017), and history of pulmonary embolism and/or venous thromboembolism (HR, 0.5; 95% CI, 0.28-0.35; P < 0.001). Filter placement team and indication were not identified as independent predictors of nonretrieval of IVC filters.

CONCLUSIONS

Patient variables identified by univariate and multivariate analyses as risk for nonretrieval of retrievable IVC filters have several implications: first, some of these patients may represent a group of patients with a low life expectancy or unresolvable underlying condition in which filter retrieval has diminishing returns and may indicate the clinical option for permanence of the filter; second, identification of risk factors for nonretrieval in patients before filter placement will help to optimize use of retrievable IVC filters and enhance retrieval rates.

Indocyanine Green Angiography Aids in Prediction of Limb Salvage in Vascular Trauma

BACKGROUND

In cases of severe vascular trauma, traditional means for assessing viability using Doppler and angiography can have limited application. Indocyanine green angiography (ICGA) allows for a rapid qualitative assessment of tissue perfusion that serves as an important adjunct to these traditional methods, which can also be particularly helpful in guiding therapy.

METHODS/RESULTS

We present a case of complicated ankle fracture with severe vascular compromise, which illustrates the role of ICGA as an assessment tool to guide therapy and decision-making in cases of acute limb threat. ICGA using SPY system (Novadaq, Bonita Springs, FL) was performed as part of our initial assessment to evaluate the extent of malperfusion and potential for revascularization. Preprocedural imaging with ICGA showed very limited uptake in the foot. Treatment was also performed with traditional angiography and infusion of intra-arterial nitroglycerin into the posterior tibial artery. Postprocedure imaging with ICGA was performed a day later and showed marked difference in the perfusion profile, with rapid uptake into the forefoot and toes, which corresponded with the patient's clinical improvement. The patient went on to have complete limb salvage.

CONCLUSIONS

The addition of ICGA for assessment of tissue perfusion in cases of complex vascular trauma has several implications: it guides surgical therapy for excision of devitalized tissue and aids in decision-making for major considerations such as revascularization efforts or amputation.

Restenosis and symptom recurrence after endovascular therapy for claudication: does duplex ultrasound correlate with recurrent claudication?

After endovascular therapy, duplex ultrasound surveillance to detect restenosis guides clinical decisions and defines treatment failure. However, the correlation between duplex ultrasound and symptom recurrence remains unclear. We reviewed our institutional experience (2007-2010) to identify patients undergoing endovascular therapy for claudication. The association between post-intervention systolic velocity ratio and patient-reported symptom recurrence was determined. We analyzed 183 follow-up visits following treatment in 88 limbs (femoropopliteal (56%) or iliac (44%) arteries). After femoropopliteal intervention, median systolic velocity ratio was higher in patients with symptom recurrence (2.99 symptomatic vs. 1.69 asymptomatic; p<0.001). Elevated systolic velocity ratio or occlusion correlated with symptom recurrence (area under receiver operator characteristic curve=0.82 [95% CI 0.74-0.83]), and systolic velocity ratio>2.5 was 71% sensitive and 72% specific for symptom recurrence. After femoropopliteal endovascular therapy for claudication, duplex ultrasound-detected restenosis is highly associated with clinical deterioration. This validates objective criteria for treatment failure in claudicants and suggests that symptom status can serve as a primary indicator of anatomic restenosis.

Risk Factors for Suboptimal Utilization of Statins and Antiplatelet Therapy in Patients Undergoing Revascularization for Symptomatic Peripheral Arterial Disease

BACKGROUND

The objective of this study was to identify risk factors for suboptimal medical therapy (defined as reported antiplatelet and statin use) among patients undergoing lower extremity bypass (LEB) and peripheral vascular interventions (PVIs) for symptomatic peripheral arterial disease (PAD).

METHODS

The Vascular Study Group of Greater New York (VSGGNY) database was used to identify all patients undergoing PVI or LEB for PAD (2011-2013). Bivariate analyses were performed to identify characteristics of patients who were not prescribed statins and/or antiplatelet agents before revascularization. Multivariate relative risk regression models were developed to identify patients at risk for suboptimal therapy, with regards to antiplatelet and statin therapy.

RESULTS

About 1,030 patients underwent endovascular therapy (n = 822; 80%) or surgical bypass (n = 208; 20%) for symptomatic PAD (57.2% claudication; 15% rest pain and 27.8% tissue loss). Overall, preoperative statin use was observed in 59%. Preoperative antiplatelet therapy was observed in 79% of patients. Bivariate analysis revealed comparatively reduced statin use among patients without other cardiovascular risk factors including hypertension (63% vs. 39.3%; P < 0.0001) and coronary artery disease (CAD) with or without prior cardiac revascularization (coronary artery bypass grafting [CABG]/percutaneous coronary intervention [PCI]; 75.2% vs. 47.4%; P < 0.0001). Multivariate relative risk regression confirmed higher rates of statin use among patients with other cardiovascular risk factors including hypertension (1.14 [1.02-1.27]; P = 0.02) and CAD with prior CABG/PCI (1.22 [1.13-1.31]; P < 0.0001). Reduced statin use was observed in patients over 80 years old. (0.92 [0.84-0.1.0]; P = 0.059). By multivariate regression, antiplatelet therapy use was associated with CAD and/or prior CABG/PCI (1.11 [1.04-1.17]; P = 0.0015) and prior peripheral revascularization (1.07 [1.01-1.13]; P = 0.03).

CONCLUSIONS

Patients with symptomatic PAD, but without an antecedent cardiovascular history, are less likely to be optimally managed with statins and antiplatelet therapy preoperatively. Given the established role of these medications in the optimal medical management of patients with PAD, this presents an opportunity for improvement in the overall vascular care of patients undergoing intervention for symptomatic PAD at VSGGNY centers.

Transradial interventions in contemporary vascular surgery practice

OBJECTIVES

Upper extremity arterial access is often required for endovascular procedures, especially for antegrade access to the visceral aortic branches. Radial arterial access has been shown previously to have low complication rates, and patients tolerate the procedure well and are able to recover quickly. However, transradial access remains relatively uncommon amongst vascular surgeons.

METHODS

The radial artery was evaluated by ultrasound to evaluate for adequate caliber, and to identify any aberrant anatomy or arterial loops. A modified Barbeau test was performed to ensure sufficient collateral circulation. A cocktail of nitroglycerin, verapamil and heparin was administered intra-arterially to combat vasospasm. Sheaths up to 6 French were utilized for interventions. On completion of the procedure, a compression band was used for hemostasis in all cases.

RESULTS

Twenty-five interventions were performed in 24 patients. The left radial artery was used in 23/25 cases (92.0%). Procedures included visceral and renal artery interventions; stent graft repair of a renal artery aneurysm; embolization of splenic, pancreaticoduodenal and internal mammary aneurysms; embolization of bilateral hypogastric arteries following blunt pelvic trauma; interventions for peripheral arterial disease; delivery of a renal snorkel graft during endovascular aortic aneurysm repair, and access for diagnostic catheters during thoracic endovascular aortic aneurysm repair. Technical success was 92.0%. There was one post-operative radial artery occlusion (4.3%) which led to paresthesias but resolved with anticoagulation. There were no instances of arterial rupture, hematoma, or hand ischemia requiring intervention.

CONCLUSIONS

Using the transradial approach, we have demonstrated a high technical success rate over a range of clinical contexts with minimal morbidity and no significant complications such as bleeding or hand ischemia. The safety profile compares favorably to historical complication rates from brachial access. Radial access is a safe and useful skill for vascular surgeons to master.

Defining risks and predicting adverse events after lower extremity bypass for critical limb ischemia

Successful treatment of patients with critical limb ischemia (CLI), hinges on the adequacy of revascularization. However, CLI is associated with a severe burden of systemic atherosclerosis, and patients often suffer from multiple cardiovascular comorbidities. Therefore, CLI patients in general represent a cohort at increased risk for procedural complications and adverse events. Although endovascular therapy represents a minimally invasive alternative to open surgical bypass, the durability of surgical reconstruction is superior, and it remains the "gold standard" approach to revascularization in CLI. Therefore, selection of the optimal treatment modality for individual patients requires careful consideration of the procedural risks and likelihood of adverse events associated with surgery. Individualized decision-making with regard to revascularization strategy requires a comprehensive understanding of the likelihood of adverse outcomes after major surgery. Here we review the risks of surgical bypass in patients with CLI, with particular emphasis on the identification of preoperative variables that predict poor outcome.