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Biomedical subjects

Luis Leon

Publications and source records attributed to Luis Leon.

8 recordsLinked to original sources
PubMed2006

Development of reflux in the perforator veins in limbs with primary venous disease.

OBJECTIVE: To determine the patterns by which perforator vein (PV) reflux develops in patients with primary chronic venous disease (CVD). METHODS: Patients with CVD who had at least two examinations with duplex ultrasonography before any treatment were included in this study. These were patients who were offered an operation at their first visit, but for various reasons treatment was postponed. All affected limbs were classified by the CEAP classification system. A detailed map of normal and refluxing sites was drawn on an anatomic chart by using several landmarks of the skin, muscle, and bone. Reflux was induced by distal limb compression followed by sudden release by using rapid-inflation pneumatic cuffs and dorsiplantar flexion. All new reflux sites were documented. The PV reflux was divided into ascending type, descending type (re-entry flow), and those that developed in new locations, which did not have reflux in any system at that level. RESULTS: The total number of patients studied was 127 (158 limbs). There were 29 limbs (18%) in 26 patients with reflux development in the PV. In total, 38 new incompetent PVs were identified. The median time for the examination was 25 months (range, 9-52 months). Reflux in a previously normal PV at a re-entry site was detected in 15, in an ascending manner from an extension of superficial vein reflux in 18, and in a new, previously intact location in 5. At the new sites, reflux in the superficial veins connected to the incompetent PVs was always present. PVs connected to the great saphenous vein system were most common (n = 27), followed by those connected to short saphenous (n = 8) and nonsaphenous (n = 3) veins. Worsening in the clinical class was observed in 11 limbs: 5 from class 2 to 3, 2 from class 2 to 4, 2 from class 3 to 4, and 2 from class 4 to 6. The worsening could not be attributed to the PV reflux alone, because other veins became incompetent as well. CONCLUSIONS: Reflux in PVs develops in ascending fashion through the superficial veins, at re-entry points, and at new sites. Worsening of CVD is observed with new PV reflux, but many other factors play a major role, and therefore a causative association is difficult to prove.

Chronic Disease↗
PubMed2006

The shape of things to come: results from a national survey of trauma surgeons on issues concerning their future.

BACKGROUND: This study seeks to characterize the opinions of practicing surgeons as a basis for formulating a plan to restructure the discipline of trauma surgery and its training path. METHODS: A 52-item questionnaire was administered to the membership of the American Association for the Surgery of Trauma, the Eastern Association for the Surgery of Trauma, and the Western Trauma Association. The survey tool investigated issues related to current and future practice. RESULTS: Response rate was 60%. Mean age was 49 years and 88% were male. The average time in practice is 15 years. The average workweek is 80 hours with 48% of that time devoted to clinical practice. About half take in-house call and about one-third receive an on-call stipend. The median annual number of major trauma cases was 50. The most important disincentives to entering the field were felt to be lifestyle issues and a limited scope of practice. Almost 90% felt their work as trauma surgeons was undervalued by society and the health care system. The great majority (88%) responded that the discipline of trauma surgery must change. Respondents feel this restructuring should include broader general surgery (83%) as well as limited orthopedic (60%) and neurosurgical trauma-related procedures (59%). About one-half of respondents favored in-house call (54%) and a practice model similar to emergency medicine (55%). Factors that would most enhance practice were thought to be guaranteed appropriate salary and guaranteed time away from work. Training in a broad range of skills was felt to be essential or useful to the trauma surgeon of the future, although few currently employ such a wide breadth of skills. CONCLUSIONS: Current practicing trauma surgeons feel that the discipline must change to remain viable. This change should entail broader training to allow more procedures in trauma, emergency surgery, critical care, and elective general surgery. The preferred practice model is a large, hospital-based, diversified group practice with a predictable lifestyle and guaranteed salary commensurate with effort. Inclusion of selected emergency orthopedic and neurosurgical procedures are viewed favorably, as is in-house call. Efforts to increase public perception of trauma surgery's value to society and its impending demise are warranted.

Attitude of Health Personnel↗
PubMed2005

The prophylactic use of inferior vena cava filters in patients undergoing high-risk spinal surgery.

Prophylactic inferior vena cava filter (IVCF) placement is advocated in some high-risk groups. We sought data regarding safety and efficacy for prophylactic IVCF placement in patients at high risk for venous thromboembolism (VTE) following major spinal reconstruction. Seventy-four spine surgery patients with contraindication to anticoagulation (44 females, 30 males; mean age 56.2) received prophylactic IVCFs. Criteria were (1) history of thromboembolism, (2) diagnosed thrombophilia, (3) malignancy, (4) bedridden >2 weeks prior to surgery, (5) staged procedures or multiple levels, (6) combined anterior/posterior approaches, (7) expected need for significant iliocaval manipulation during exposure, and (8) single-stage anesthetic time >8 hr. Seventy patients had at least two risk factors. All received IVCFs prior to the first stage of spine reconstruction. Patients were evaluated for filter complications, deep vein thrombosis (DVT), and pulmonary embolism (PE). Patients' lower extremity veins from groin to ankle were imaged weekly until discharge using duplex ultrasound (DUS). One-third also underwent thoracic and pelvic computed tomography scans, and the pelvic veins, IVC, and pulmonary vasculature were evaluated for VTE. Multiple DUS (n = 198, mean 2.6 studies per patient) were performed in 68 patients. At a mean follow-up of 11 months, one of the patients developed PE. Twenty-seven limbs in 23 patients developed DVT. Five limbs had isolated calf DVT, and 22 had proximal vein involvement. Insertion site DVT accounted for nearly one-third of the DVTs. Six patients died from unrelated complications. There was one technical error with an IVCF deployed in the iliac vein. Despite a high incidence of DVT following high-risk spinal surgery, prophylactic IVCF placement appears to protect patients from PE.

Adolescent↗
PubMed2005

Study of the venous reflux progression.

BACKGROUND: Patients with chronic venous disease (CVD) often ask whether elective vein surgery could be delayed without consequences. Because the natural history of CVD is not well known, this study was designed to determine its progression in such patients. METHODS: One hundred and sixteen limbs in 90 patients who had at least 2 exams with duplex ultrasound (DU) scanning prior to vein surgery at a university medical center were studied. These were patients who were offered an operation but for various reasons were treated at a later stage. Patients were classified by the CEAP system. RESULTS: The mean age of the patients was 49 years (range, 23 to 81 years). A second DU scan was performed 1 to 43 months after the initial exam (median, 19 months). Eighty-five limbs (73.3%) were unchanged. Thirteen limbs (11.2%) had progression of clinical stage, and seven had progression on DU scanning as well. Seven limbs progressed from C2 to C3, four limbs from C3 to C4, and two limbs from C4 to C6. Thirty-four limbs had a documented change on repeat DU scanning. In 3 of these limbs, reflux was missed on the initial exam; therefore, 31 limbs had progression of disease. The great saphenous vein and tributaries were the most often anatomic sites affected by a change, followed by perforators. Seventeen limbs (14.7%) had extension of pre-existing reflux, and 14 (12.1%) had reflux in a new segment. In 11 of these limbs, a change in the initial plan for treatment was required. Symptomatic or DU changes were noted 6 months or later in 95% of limbs and 74.2% of limbs with disease progression were diagnosed at 12 months or later. All but one of the 13 symptomatic limbs developed symptoms at least a year later. CONCLUSION: Nearly one third of patients with venous reflux had progression. Anatomic extension is frequent with disease progression but not a pre-requisite. Progression was found in most limbs 6 months after the initial study. Patients undergoing treatment for their veins may need another DU exam if this time interval is exceeded.

Adult↗
PubMed2005

Neovascularization in acute venous thrombosis.

OBJECTIVE: The aim of this study was to describe the phenomenon of arteriovenous fistula (AVF) formation in venous thrombus. METHODS: Patients referred to the vascular laboratory for evaluation for deep venous thrombosis were included. Duplex ultrasound scanning was used to detect flow within the thrombus. The flow patterns and the resistivity index were obtained in the veins above/proximal and below/distal to the thrombus, in the adjacent arteries, and within the perivenous vessels. Patients with trauma, hemodialysis access, endovenous ablation, known AVF, or inflammatory conditions were excluded. RESULTS: There were 22 patients with AVF flow in thrombosed veins. Deep veins were involved in 15 cases and superficial veins in the remainder. Perivenous vessels feeding the AVF in the thrombus could be clearly identified in 16 patients (19 vein segments). In 21 of 22 patients, multiple flow channels were present throughout the involved thrombosed vein segment. These flow channels were isolated to a single vein segment. They measured <4 cm in length in 19 cases and were more extensive in the remaining three. Reflux within the vein segment was identified in 13 cases. Local symptoms that could be attributed to the arterialization of thrombosed veins occurred in four cases, and none of the patients manifested systemic symptoms. The flow within the thrombus had high end-diastolic velocities with a mean resistivity index of 0.48 (SD, 0.08), which is typical of a fistula flow pattern. The flow in the main arteries was unaffected. CONCLUSION: Neovessels were found with AVF flow in thrombi of superficial and deep veins. They had variable length and multiple flow channels, with inflow from perivenous arteries. The flow in the adjacent main arteries was not affected, and no systemic symptoms were detected. The exact etiology and natural history of this phenomenon are not known, and its clinical significance is unclear.

Adult↗
PubMed2005

Arteriovenous access: managing common problems.

The creation and maintenance of hemoaccess occupies a significant portion of most vascular and general surgery practices. In this article, the methods used to detect hemoaccess at risk for failure and the endovascular and surgical techniques used to prolong or restore their patency are reviewed. Also, the management of hemoaccess infection, aneurysmal degeneration, false aneurysm formation, and symptomatic arterial steal syndrome are described.

Aneurysm, False↗
PubMed2003

Vascular grafts.

Autogenous vein is the conduit of choice in the surgical creation of bypasses of small-to-medium-caliber vessels in patients with peripheral occlusive arterial disease and will remain so for the near future. The success rate of bypasses using conduits of diameters greater than 6 mm has been excellent, whereas the majority of bypasses using smaller conduits fail within 5 years. In addition, due to a steep increase in rates of diabetes and decreasing cardiovascular mortality rates, increasing challenges are presented by this population. These facts have motivated much of the research in the cardiovascular arena over the past four decades, with improved techniques and new materials. Strategies to improve outcomes include the use of alternative materials including autologous, nonautologous and prosthetic grafts, utilizing different methods for their harvesting and preservation; tissue engineering, using either polymer- or biological-based scaffolds for cell seeding; endovascular methodologies; and gene therapy. This report presents an overview of the several options currently available in the management of patients with peripheral arterial occlusive disease, as well as the ongoing research directed towards the creation of an artificial engineered vessel, discussing experimental work in which endothelial cells have been seeded on different scaffolds and finally the potential application of gene therapy in the field of vascular reconstruction.

Arterial Occlusive Diseases↗