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Anton N Sidawy

Publications and source records attributed to Anton N Sidawy.

At least 19 recordsLinked to original sources
PubMed2006

The effects of the type of anesthesia on outcomes of lower extremity infrainguinal bypass.

OBJECTIVE: Three main types of anesthesia are used for infrainguinal bypass: general endotracheal anesthesia (GETA), spinal anesthesia (SA), and epidural anesthesia (EA). We analyzed a large clinical database to determine whether the type of anesthesia had any effect on clinical outcomes in lower extremity bypass. METHODS: This study is an analysis of a prospectively collected database by the National Surgical Quality Improvement Program (NSQIP) of the Veterans Affairs Medical Centers. All patients from 1995 to 2003 in the NSQIP database who underwent infrainguinal arterial bypass were identified via Current Procedural Terminology codes. The 30-day morbidity and mortality outcomes for various types of anesthesia were compared by using univariate analysis and multivariate logistic regression to control for confounders. RESULTS: The NSQIP database identified 14,788 patients (GETA, 9757 patients; SA, 2848 patients; EA, 2183 patients) who underwent a lower extremity infrainguinal arterial bypass during the study period. Almost all patients (99%) were men, and the mean age was 65.8 years. The type of anesthesia significantly affected graft failure at 30 days. Compared with SA, the odds of graft failure were higher for GETA (odds ratio, 1.43; 95% confidence interval [CI], 1.16-1.77; P = .001). There was no statistically significant difference in 30-day graft failure between EA and SA. Regarding cardiac events, defined as postoperative myocardial infarction or cardiac arrest, patients with normal functional status (activities of daily living independence) and no history of congestive heart failure or stroke did worse with GETA than with SA (odds ratio, 1.8; 95% CI, 1.32-2.48; P < .0001). There was no statistically significant difference between EA and SA in the incidence of cardiac events. GETA, when compared with SA and EA, was associated with more cases of postoperative pneumonia (odds ratio: 2.2 [95% CI, 1.1-4.4; P = .034]. There was no significant difference between EA and SA with regard to postoperative pneumonia. Compared with SA, GETA was associated with an increased odds of returning to the operating room (odds ratio, 1.40; 95% CI, 1.20-1.64; P < .001), as was EA (odds ratio, 1.17; 95% CI, 1.05-1.31; P = .005). GETA was associated with a longer surgical length of stay on univariate analysis, but not after controlling for confounders. There was no significant difference in 30-day mortality among the three groups with univariate or multivariate analyses. CONCLUSIONS: Although GETA is the most common type of anesthesia used in infrainguinal bypasses, our results suggest that it is not the best strategy, because it is associated with significantly worse morbidity than regional techniques.

Aged↗
PubMed2006

Thiamine (vitamin B1) improves endothelium-dependent vasodilatation in the presence of hyperglycemia.

Brachial artery vasoactivity (BAVA) is a reliable, noninvasive method of assessing endothelium-dependent vasodilatation (EDV) in vivo. Acute hyperglycemia, impaired glucose tolerance (IGT), and diabetes mellitus impair EDV, a precursor to atherosclerosis. Thiamine is a coenzyme important in intracellular glucose metabolism. The purpose of this study was to evaluate the effect of thiamine on BAVA in the presence of hyperglycemia. Ten healthy subjects (group H, mean age 27 years), 10 patients with impaired glucose tolerance by World Health Organization criteria (group IGT, mean age 65 years), and 10 patients with non-insulin-dependent diabetes mellitus (group NIDDM, mean age 50 years) were studied. Duplex ultrasound was used to measure brachial artery flow changes in response to reactive hyperemia following brachial artery tourniquet occlusion for 5 min. This test was performed after a 10 hr fast and at 30, 60, and 120 min after a 75 g oral glucose challenge along with measurements of blood glucose level (BGL). A week later, BAVA evaluation was repeated after administration of 100 mg of intravenous thiamine. BAVA (% increased blood flow) at peak and trough BGL was compared with and without thiamine. BAVA at peak glucose improved from 69.0 +/- 6.4% to 152.8 +/- 22.9% in group H (p < 0.005), from 57.6 +/- 12.6% to 139.7 +/- 12.4% in group IGT (p < 0.005), and from 57.8 +/- 8.3% to 167.8 +/- 11.6% in group NIDDM (p < 0.005) following administration of thiamine. On the other hand, at trough glucose levels, BAVA remained essentially unchanged in group H (prethiamine 83.8 +/- 6.5% vs. post-thiamine 83.8 +/- 17.0%, p > 0.05) as well as group IGT (prethiamine 96.7 +/- 8.5% vs. post-thiamine 104.0 +/- 17.4%, p > 0.05). BAVA at trough glucose was not measured in group NIDDM secondary to trough BGL > 140 mg/dL. EDV was improved by thiamine in the presence of hyperglycemia in healthy subjects and in patients with IGT and NIDDM. The mechanism by which thiamine improves EDV is not due to a glucose-lowering effect as thiamine had no effect on EDV under normoglycemic conditions. Routine administration of thiamine might improve endothelial function and therefore slow the development and progression of atherosclerosis, especially in patients with IGT and NIDDM who are prone to develop accelerated atherosclerosis.

Adult↗
PubMed2006

Hypoxia attenuates insulin-induced proliferation and migration of human diabetic infrapopliteal vascular smooth muscle cells.

The proliferative effects of insulin on infrapopliteal vascular smooth muscle cells (VSMCs) have been established. We examined the effect of hypoxia in the presence and absence of insulin on the proliferation and migration of human diabetic infrapopliteal VSMCs in vitro. VSMCs isolated from the infrapopliteal arteries of male diabetic patients of identical disease and clinical patterns undergoing below-knee amputation were harvested and grown to subconfluence. Cells were then exposed to control medium (M199/1% fetal bovine serum/2% antibiotic-antimycotic) or control medium with 100 ng/mL insulin in oxygen concentrations of 17% (normoxia), 5%, and 1%. Cellular proliferation was assayed using [methyl-3H]-thymidine incorporation. Migration assays were performed using the Corning Costar Transwell system. Lactate dehydrogenase was assayed and compared among groups as a marker for cytotoxicity. VSMCs in normoxic conditions (17%) had a significant increase in both proliferation (100 +/- 6.5% vs. 124 +/- 4.7%, p = 0.007) and migration [73.2 +/- 9.3 vs. 118.1 +/- 14.9 cells/4 high-power fields (HPF), p = 0.03] when exposed to insulin. Of cells exposed to insulin, those at both 5% (75.9 +/- 7.9%, p = 0.0001) and 1% (73.6 +/- 4%, p < 0.0001) hypoxia proliferated at a significantly decreased rate compared with cells at normoxia (124 +/- 4.7%). Migration of these insulin-exposed cells was significantly decreased at 1% hypoxia (63.1 +/- 9.0 cells/4HPF) compared to those at normoxia (118.1 +/- 14.9 cells/4HPF, p = 0.006) and 5% hypoxia (101.2 +/- 10.0 cells/4HPF, p = 0.01). There were no significant differences in migration between cells at normoxia and 5% hypoxia. Finally, hypoxia and insulin exerted no significant effect on cytotoxicity. The proliferative and promigratory effects of insulin on diabetic VSMCs are attenuated in hypoxic conditions in a manner unrelated to cytotoxicity.

Cell Hypoxia↗
PubMed2006

Endovascular abdominal aortic aneurysm repair: long-term outcome measures in patients at high-risk for open surgery.

PURPOSE: The study was conducted to determine the outcome in the United States after endovascular repair (EVAR) of infrarenal abdominal aortic aneurysms (AAAs) in patients at high-risk for open surgery by using independently audited, high-compliance, chart-verified data sets, and to compare those results with open surgery. METHODS: High-risk was defined to match a recent European trial (EVAR2) and included age of > or =60 years with aneurysm size of > or =5.5 cm, plus at least one cardiac, pulmonary, or renal comorbidity. Data from five multicenter investigational device exemption clinical trials leading to Food and Drug Administration (FDA) approval were analyzed. Of 2216 EVAR patients, 565 met the high-risk criteria. Of 342 surgical controls (OPEN), 61 met high-risk criteria. Primary outcome comparisons included AAA-related death, all-cause death, and aneurysm rupture. Secondary measures were endoleak, AAA sac enlargement, and migration. RESULTS: Average age of the high-risk EVAR subset was 76 +/- 7 years vs 74 +/- 6 years OPEN (P = 0.07), mean EVAR AAA size was 6.4 +/- 0.8 cm vs 6.6 +/- 1.0 cm OPEN (P = .33), and average EVAR follow-up was 2.7 years vs 2.5 years OPEN. The 30-day operative mortality was 2.9% in EVAR vs 5.1% in OPEN (P = .32). The AAA-related death rate after EVAR was 3.0% at 1 year and 4.2% at 4 years compared with 5.1% at both time points after OPEN (P = .58). Overall survival at 4 years after EVAR was 56% vs 66% in OPEN (P = .23). After treatment, EVAR successfully prevented rupture in 99.5% at 1 year and in 97.2% at 4 years. CONCLUSIONS: Endovascular repair of large infrarenal AAAs in anatomically suited high-surgical-risk patients using FDA-approved devices in the United States is safe and provides lasting protection from AAA-related mortality. EVAR mortality remained comparable with OPEN up to 4 years. The decision to treat AAAs in patients with advanced age and significant comorbidities must be individualized and carefully considered, but repair provides excellent protection from AAA-related death.

Aged↗
PubMed2006

Physiological changes in venous hemodynamics associated with elective fasciotomy.

It has been postulated that lower extremity fasciotomy may disrupt the calf musculovenous pump and predisposes to development of chronic venous insufficiency (CVI). However, studies based on trauma patients who undergo emergent fasciotomy are confounded by the possibility of concomitant vascular and soft tissue injury and use historical controls. This is a prospective study that evaluates venous hemodynamics in young patients undergoing elective fasciotomy for chronic exertional compartment syndrome (CECS), eliminating the problems associated with retrospective study of trauma patients. CECS was diagnosed by history and, when indicated, measurement of compartment pressures. Prior to elective two- or four-compartment fasciotomy, each patient underwent lower extremity air plethysmography (APG) and colorflow duplex ultrasonography. These studies were repeated a minimum of 6 weeks postoperatively. Fifteen patients who had fasciotomies for CECS were studied; two of these patients had bilateral fasciotomies for a total of 17 limbs. There were 13 male and two female patients (average age 31.2 years). APG and colorflow duplex were performed an average of 12 weeks after fasciotomy. Outflow fraction, venous volume, and ejection volume showed no significant changes postoperatively. However, the venous filling index (VFI) increased (0.9 +/- 0.1 vs. 1.1 +/- 0.1 mL/sec; p < 0.05, paired t-test), the ejection fraction tended to decrease (59 +/- 4% vs. 52 +/- 2%; p < 0.08, paired t-test), and the residual volume fraction (RVF) increased (26 +/- 3% vs. 36 +/- 5%; p < 0.05, paired t-test). There were no patients with evidence of deep venous reflux. Two extremities with preoperative greater saphenous vein (GSV) reflux did not worsen, and three extremities developed new GSV reflux following fasciotomy, although VFI remained normal in each extremity. Elective fasciotomy for CECS does not lead to significant venous reflux but likely does diminish calf muscle pump function and increases RVF moderately in young adult patients. With longer follow-up this diminished calf muscle pump function may increase the risk of CVI.

Adult↗
PubMed2006

Training in vascular medicine for vascular surgeons--what is it and how will we accomplish it?

The goal of vascular surgery training program should be the training of a complete vascular surgeon proficient not only in the management of established peripheral vascular disease but also in the prevention of the atherosclerotic process through management of risk factors. In addition, vascular surgeons should develop expertise in the treatment of nonatherosclerotic arterial disease, nonoperative management of acute and chronic venous disease, lymphedema, and the treatment of various coagulation disorders. To accomplish these goals, we should establish a comprehensive, patient-centered vascular medicine curriculum and appropriate methods for its implementation.

Atherosclerosis↗
PubMed2006

Transforming growth factor-beta and wound healing.

Acute and chronic wounds are a source of significant morbidity for patients, and they demand a growing portion of health-care time and finances to be devoted to their care. Transforming growth factor-beta (TGF-beta) has surfaced from abundant research as a key signal in orchestrating wound repair. In beginning this review, we discuss the inflammatory, proliferative, and maturational phases of wound healing. We then focus on TGF-beta by first discussing the pathway from its production to the target cell where Smad proteins execute an intracellular signaling cascade. To review TGF-beta's role in wound healing, we discuss the actions of it individually on keratinocytes, fibroblasts, endothelial cells, and monocytes, which are the major cell types involved in wound repair. From illustrating these cellular actions of TGF-beta, we summarize its multipotent role in the process of wound repair. As a clinical correlation, we also review research dedicated to the involvement of TGF-beta in venous stasis ulcers.

Animals↗
PubMed2006

Carotid plaque morphologic characteristics.

Carotid artery atherosclerosis is predominantly believed to mirror atherosclerosis elsewhere in the body. Endothelial injury results in expression of cell surface adhesion molecules with expression of sequence of genes involved in the inflammatory pathway and expression of proinflammatory cytokines. The combination of the inflammatory mediators and contribution by monocytes infiltrating the intima and vascular smooth muscle cell proliferation result in the development of atheromatous plaque with a lipid-rich necrotic core. Complications of these atheromatous plaques can lead to plaque instability, rupture, and subsequent hemorrhage or ulceration. The significant risk factors, characteristics associated with symptoms, and available diagnostic imaging modalities are also discussed with review of the relevant literature.

Carotid Artery Diseases↗
PubMed2005

Inactivation of ELF/TGF-beta signaling in human gastrointestinal cancer.

TGF-beta/Smads regulate a wide variety of biological responses through transcriptional regulation of target genes. ELF, a beta-spectrin, plays a key role in the transmission of TGF-beta-mediated transcriptional response through Smads. ELF was originally identified as a key protein involved in endodermal stem/progenitor cells committed to foregut lineage. Also, as a major dynamic adaptor and scaffolding protein, ELF is important for the generation of functionally distinct membranes, protein sorting and the development of polarized differentiated epithelial cells. Disruption of elf results in the loss of Smad3/Smad4 activation and, therefore, a disruption of the TGF-beta pathway. These observations led us to pursue the function of ELF in gastrointestinal (GI) epithelial cell-cell adhesion and tumor suppression. Here, we show a significant loss of ELF and reduced Smad4 expression in human gastric cancer tissue samples. Also, of the six human gastric cancer cell lines examined, three show deficient ELF expression. Furthermore, we demonstrate the rescue of E-cadherin-dependent homophilic cell-cell adhesion by ectopic expression of full-length elf. Our results suggest that ELF has an essential role in tumor suppression in GI cancers.

Antibodies, Monoclonal↗
PubMed2005

Aortic angiosarcoma presenting as distal arterial embolization.

Aortic angiosarcoma is a rare, malignant neoplasm of the vasculature, with 24 case reports in the literature. Patients usually present with either aneurysmal or occlusive disease. Treatment consists of en bloc resection of the vessel and contiguous structures with postoperative chemoradiation therapy. Despite surgery and adjunctive measures, prognosis remains dismal as a result of early metastasis and late diagnosis. We report a case of aortic angiosarcoma that presented with distal thromboembolic phenomenon.

Aged↗
PubMed2005

Characteristics of the applicant pool to vascular surgery residency programs.

OBJECTIVE: Based on the significant number of unfilled vascular fellowship positions in the 2004 National Residency Matching Program (NRMP) and the perception of program directors that the quality of candidates is deteriorating, the Issues Committee of the Association of Program Directors in Vascular Surgery (APDVS) explored the characteristics and the trend of the applicant pool to develop recommendations for improvement. METHODS: The Electronic Residency Application Service (ERAS) database was queried for the total number of applicants, medical school, gender, and age, among other characteristics. The vascular surgery applicant pool was compared to the applicant pool for general surgery; the applicant pool for all fellowship positions, including a variety of medical subspecialties; the applicant pool for all residency positions; and the applicant pool for colorectal surgery, the only other surgical subspecialty participating in ERAS in 2004. NRMP data was used prior to 2004. The chi(2) test was used for statistical analysis, with significance set at P < .05. RESULTS: In the 2004 match for June 2005 positions, there were 100 applicants for 110 first-year vascular surgery positions in 90 programs. In 1989, there were 123 applicants for 56 positions in 49 programs. In 1989, 55% of vascular surgery applicants did not match; whereas in 2004, only 7% were unmatched. Although the overall number of vascular surgery applicants has remained relatively stable, the number of United States applicants has decreased from 89% in 1990 to 68% in 2004 (P < .01). There was a significant geographic variation: 34% of those in the applicant pool came from the state of New York, but 23 states did not contribute a single applicant to the pool. In addition, vascular surgery, like other fellowships, attracts fewer female applicants. CONCLUSIONS: The data from the ERAS database support the impression held by many in the vascular surgery education community that the size of the applicant pool for vascular surgery fellowship positions has remained stagnant, while the number of positions has significantly increased. Strategies to increase the size and quality of the applicant pool are needed.

Adult↗
PubMed2005

Evaluation of the microcirculation in vascular disease.

Insufficient blood flow through end-resistance arteries leads to symptoms associated with peripheral vascular disease. This may be caused in part by poor macrocirculatory inflow or impaired microcirculatory function. Dysfunction of the microcirculation occurs in a similar fashion in multiple tissue beds long before the onset of atherosclerotic symptoms. Impaired microcirculatory vasodilatation has been shown to occur in certain disease states including peripheral vascular disease, diabetes mellitus, hypercholesterolemia, hypertension, chronic renal failure, abdominal aortic aneurysmal disease, and venous insufficiency, as well as in menopause, advanced age, and obesity. Microcirculatory structure and function can be evaluated with transcutaneous oxygen, pulp skin flow, iontophoresis, and capillaroscopy. We discuss the importance of the microcirculation, investigative methods for evaluating its function, and clinical applications and review the literature of the microcirculation in these different states.

Humans↗
PubMed2005

Evaluation of macrocirculatory endothelium-dependent and endothelium-independent vasoreactivity in vascular disease.

Macrocirculatory endothelium-dependent and independent vasodilatation is integral to tissue-bed oxygen delivery and homeostasis. Dysfunction of macrocirculatory vasoreactivity is a precursor to atherosclerosis and occurs in a similar fashion in multiple tissue beds long before the onset of symptoms. Impaired macrocirculatory vasodilatation has been shown to occur in certain disease states including diabetes mellitus, hypercholesterolemia, chronic renal failure, peripheral arterial atherosclerosis, and abdominal aortic aneurysms, as well as secondary to smoking, advanced age, menopause, high-fat diet, and sedentary lifestyle. Brachial artery vasoreactivity is a noninvasive means of assessing macrocirculatory vasodilatory capacity that may help identify patients at increased risk for peripheral and cardiovascular disease and allow for objective assessment and monitoring of treatment. Endothelium-dependent vasoreactivity, or flow-mediated dilatation, is measured after brachial artery occlusion with a pneumatic blood pressure cuff, and endothelium-independent vasoreactivity is measured after the administration of sublingual nitroglycerin. The accuracy of brachial artery vasoreactivity is dependent on hematologic variables, as well as diurnal, day-to-day, ultrasound operator, and reader variations; however, the overall coefficient of variation is only 1.8%. We discuss the importance of the macrocirculation, investigative methods for evaluating macrocirculatory vasoreactivity, and review the literature of vasoreactivity in these different states.

Atherosclerosis↗
PubMed2004

Influence of renal insufficiency on limb loss and mortality after initial lower extremity surgical revascularization.

OBJECTIVE: Limb loss after lower extremity surgical revascularization occurs relatively frequently in patients receiving dialysis. The goal of the present study was to determine whether patients with milder degrees of renal insufficiency are also at risk for this complication. MATERIAL AND METHODS: This cohort study was carried out at the Department of Veterans Affairs (VA). The study sample consisted of 9932 patients undergoing an initial surgical revascularization procedure between October 1, 1995, and September 30, 2000, recorded by the VA National Surgical Quality Improvement Program (NSQIP). We examined the occurrence of major amputation within 1 year of lower extremity surgical revascularization by level of renal function. RESULTS: Eleven percent of study patients underwent major lower extremity amputation within 1 year of NSQIP-documented lower extremity revascularization surgery: 10% (739 of 7335) of patients with normal renal function, 11% (251 of 2210) of patients with moderately reduced renal function, 12% (24 of 205) of patients with severe renal insufficiency, and 29% (53 of 182) of patients receiving dialysis. After adjustment for demographic characteristics and comorbid conditions, only patients receiving dialysis were at significantly increased risk for amputation, compared with patients with normal renal function (odds ratio, 2.46; 95% confidence interval, 1.74-3.47; P<.001). Compared with all other veterans undergoing bypass procedures, patients receiving dialysis were more likely to have a wound infection; a diagnostic code for lower extremity gangrene, infection, or ischemic ulceration; an elevated white blood cell count; and preoperative sepsis at the time of initial revascularization. In addition, they were more likely to have a preoperative hospital stay longer than 1 week, undergo concurrent minor amputation, and undergo an outflow (vs inflow) procedure. CONCLUSION: Only patients receiving dialysis, and not patients with milder degrees of renal insufficiency, appear to be at higher risk for limb loss after revascularization, compared with patients with normal renal function. Further studies are needed to determine why patients receiving dialysis are at a singularly increased risk for limb loss after lower extremity revascularization and whether their more frequent presentation with limb-threatening infection at the time of revascularization reflects late presentation for surgery or a more rapid course of peripheral arterial disease in this patient group.

Aged↗
PubMed2004

Choice of vascular surgery as a specialty: survey of vascular surgery residents, general surgery chief residents, and medical students at hospitals with vascular surgery training programs.

PURPOSE: Under the direction of the Association of Program Directors in Vascular Surgery, a survey was mailed to vascular surgery residents (VSRs), general surgery chief residents (GS-CRs), and fourth-year medical students (MSs) to better define reasons why trainees do and do not choose vascular surgery as a career. METHODS: Questionnaires were mailed to all accredited VSR programs and their associated GS programs in the United States and Canada in 2001 (survey 1) and in 2003 (survey 2) and to 2 medical schools with VSR programs in 2001. A total of 197 VSRs, 169 GS-CRs, and 78 MSs responded (overall program response rate of 78% for VSRs, 46% for GSRs, 20% for MSs). A scoring system was assigned, with 1.0 the least important and 5.0 the most important reasons to choose or not choose vascular surgery. RESULTS: Technical aspects, role of mentors, and complex decision making involved in vascular surgery were the most important reasons that VSRs, GS-CRs, and MSs would choose vascular surgery as a specialty (average scores > or =4.0 for VSRs and GS-CRs; > or =3.5 for MSs). Responses of GS-CRs and VSRs did not vary significantly between surveys 1 and 2, except endovascular capabilities of vascular surgeons had a more important role in choosing vascular surgery, and future loss of patients to other interventionalists had a more important role in not choosing this specialty in the more recent survey of GS-CRs and VSRs. MSs identified lifestyle as a surgical resident (4.3) and as a surgeon (4.2) as the most important negative factors. A training paradigm consisting of 4 years general surgery + 2 years vascular surgery with a GS certificate was favored by 64% of GS-CRs and 48% of VSRs, compared with a paradigm of 5 years + 2 years with a general surgery certificate, which was favored by 29% of GS-CRs and 25% of VSRs, or 3 years + 3 years without a general surgery certificate, favored by 7% of GS-CRs and 27% of VSRs. Of note, 86% of MSs favored 3 years general surgery + 3 years vascular surgery or 2 years general surgery + 4 years vascular surgery compared with longer general surgery training periods. CONCLUSION: These findings may help vascular surgery program directors devise strategies to attract future trainees. The importance of mentorship to general surgery junior residents and medical students in choosing vascular surgery cannot be overestimated. Endovascular capabilities of vascular surgeons have an increasingly positive role in career choice by GS-CRs and VSRs, but these residents express increasing concerns about potential loss of patients to other specialists. Lifestyle concerns are the most important reasons why medical students do not choose vascular surgery as a career.

Adult↗