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1.
PLoS One ; 17(10): e0276522, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36288347

RESUMEN

A surface plasmon polariton (SPP) is an excitation resulting from the coupling of light to a surface charge oscillation at a metal-dielectric interface. The excitation and detection of SPPs is foundational to the operating mechanism of a number of important technologies, most of which require SPP excitation via direct reflectance, commonly achieved via Attenuated Total Reflection (ATR) using the Kretschmann configuration. As a result, the accessible modes are fundamentally high-loss "leaky modes," presenting a critical performance barrier. Recently, our group provided the first demonstration of "forbidden," or guided-wave plasmon polariton modes (GW-PPMs), collective modes of a MIM structure with oscillatory electric field amplitude in the central insulator layer with up to an order of magnitude larger propagation lengths than those of traditional SPPs. However, in that work, GW-PPMs were accessed by indirect reflectance using Otto configuration ATR, making them of limited applied relevance. In this paper, we demonstrate a technique for direct reflectance excitation and detection of GW-PPMs. Specifically, we replace the air gap used in traditional Otto ATR with a low refractive index polymer coupling layer, mirroring a technique previously demonstrated to access Long-Range Surface Plasmon Polariton modes. We fit experimental ATR data using a robust theoretical model to confirm the character of the modes, as well as to explore the potential of this approach to enable advantageous propagation lengths. The ability to excite GW-PPMs using a device configuration that does not require an air gap could potentially enable transformative performance enhancements in a number of critical technologies.


Asunto(s)
Refractometría , Resonancia por Plasmón de Superficie , Resonancia por Plasmón de Superficie/métodos , Polímeros , Modelos Teóricos , Metales/química
2.
Ann Vasc Surg ; 68: 192-200, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32339695

RESUMEN

BACKGROUND: The prevalence of obesity is increasing in the United States. The treatment of end-stage renal disease (ESRD) via hemodialysis spans the spectrum of body mass index (BMI). This study examines the impact of BMI on outcomes of autogenous fistulas for hemodialysis access in a large population-based cohort of patients. METHODS: A retrospective study of all patients in the prospectively maintained United States Renal Database System who initiated hemodialysis between 2007 and 2014 was performed. Chi-squared test, t-tests, Kaplan-Meier estimates, log-rank tests, multivariable logistic and Cox regression analysis were employed to evaluate access maturation, interventions, patency, and mortality. RESULTS: There were 300,778 patients studied. Of these, 9,394 (3.1%) were underweight, 87,351 (29.1%) were normal weight, 86,101 (28.6%) were overweight, 57,047 (19%) were obese class I, 31,077 (10.3%) were obese class II, and 29,808 (9.9%) were obese class III. There was no significant difference in maturation for patients who were underweight (adjusted hazard ratio [aHR] 0.97, 95% CI 0.89-1.06, P = 0.48), overweight (aHR 1.01, 95% CI 0.97-1.05, P = 0.66), obese class I (aHR 1.05, 95% CI 0.99-1.09, P = 0.22), or obese class II (aHR 1.01, 95% CI 0.94-1.05, P = 0.98 relative to normal weight. However, there was a 6% decrease in maturation for obese class III patients (aHR 0.94, 95% CI 0.89-0.99, P = 0.02) compared to normal weight patients. Primary (aHR 0.93, 95% CI 0.91-0.96, P < 0.001), primary assisted (aHR 0.90, 95% CI 0.88-0.93, P < 0.001), and secondary patency (aHR 0.89, 95% CI 0.86-0.92, P < 0.001) were lower for underweight compared to normal weight patients. There was 8%, 10%, and 7% decrease in primary (aHR 0.92, 95% CI 0.90-0.93, P < 0.001), primary assisted (aHR 0.90, 95% CI 0.88-0.92, P < 0.001), and secondary patency (aHR 0.93, 95% CI 0.91-0.94, P < 0.001) respectively for patients in obese class III compared to patients with normal weight. There was an increase in patient survival with increasing BMI. CONCLUSIONS: In this population-based cohort of hemodialysis-dependent patients, severe obesity was associated with a decrease in fistula maturation. Extremes of BMI were associated with lower patency, but higher BMI was associated with better patient survival. Obese patients nearing ESRD might require earlier referral for arteriovenous fistula (AVF) placement in order to allow for maturation and AVF use at incident hemodialysis.


Asunto(s)
Derivación Arteriovenosa Quirúrgica , Índice de Masa Corporal , Enfermedades Renales/terapia , Obesidad/diagnóstico , Diálisis Renal , Anciano , Anciano de 80 o más Años , Derivación Arteriovenosa Quirúrgica/efectos adversos , Derivación Arteriovenosa Quirúrgica/mortalidad , Bases de Datos Factuales , Femenino , Humanos , Enfermedades Renales/diagnóstico , Enfermedades Renales/mortalidad , Masculino , Persona de Mediana Edad , Obesidad/mortalidad , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Índice de Severidad de la Enfermedad , Delgadez/diagnóstico , Factores de Tiempo , Resultado del Tratamiento , Estados Unidos , Grado de Desobstrucción Vascular
3.
J Vasc Surg ; 71(6): 1941-1953.e1, 2020 06.
Artículo en Inglés | MEDLINE | ID: mdl-32085961

RESUMEN

BACKGROUND: There are limited data on the impact of carotid angioplasty and stenting (CAS)-related changes in blood pressure, heart rate, and preprocedural medications on periprocedural stroke in contemporary, real-world practice. This study evaluates the risk attributable to the CAS-related hemodynamic events and the impact preprocedural medications have on mitigating this risk in a large, population-based cohort. METHODS: We studied all patients in the Vascular Quality Initiative who underwent CAS between January 2006 and December 2016. Kaplan-Meier, multivariable logistic, and Cox regression analyses were used to evaluate the impact of periprocedural hypertension, hypotension, bradycardia, and medication use on immediate periprocedural stroke (IPPS), 30-day, and 1-year stroke. RESULTS: Of the 13,698 CAS procedures studied, 1239 (9.1%), 1824 (13.3%), and 1333 (9.7%) patients experienced periprocedural hypertension, hypotension, and bradycardia, respectively. IPPS was 3.2% vs 2.1% vs 0.65% (P < .001), comparing patients with periprocedural hypertension vs hypotension vs normotension and 1.4 vs 1.0% (P = .19) for bradycardic vs nonbradycardic patients. Periprocedural hypertension was associated with a four-fold increase in IPPS (adjusted odd ratio [aOR], 3.97; 95% confidence interval [CI], 2.63-5.99; P < .001). periprocedural hypotension and bradycardia were associated with 5.5-fold (aOR, 5.56; 95% CI, 3.24-9.52; P < .001) and 2.3-fold (aOR, 2.31; 95% CI, 1.26-4.25; P = .007) increases in IPPS among patients with carotid symptoms. There was 76% decrease in IPPS for patients who did not experience a periprocedural hemodynamic event (aOR, 0.24; 95% CI, 0.16-0.35; P < .001). Unlike preprocedural beta-blockers and angiotensin-converting enzyme inhibitors, prophylactic antibradyarrhythmic agents conferred a 58% reduction in IPPS among patients with carotid symptoms (aOR, 0.42; 95% CI, 0.23-0.78; P = .006). The periprocedural hemodynamic events were also associated with 7.7-fold increase in myocardial infarction (aOR, 7.70; 95% CI, 4.77-12.45; P < .001), a 2.2-fold increase in 30-day mortality (aOR, 2.24; 95% CI, 1.61-3.12; P < .001), and a 16% increase in length of stay (aOR, 1.16; 95% CI, 0.04-2.28; P = .042). The occurrence of these hemodynamic events is higher in patients with prior cardiac disease and the difference in periprocedural outcomes extended to 1 year. CONCLUSIONS: Periprocedural hemodynamic events are associated with an increase in periprocedural stroke, myocardial infarction, death, and length of stay. Periprocedural hypertension in all patients; hypotension and bradycardia in patients with symptomatic carotid disease are associated with significant increase in IPPS. Prophylactic antibradyarrhythmic agents are associated with decrease in bradycardia and IPPS. These results heighten the need to anticipate and promptly address these CAS-related hemodynamic events, especially in susceptible patients.


Asunto(s)
Angioplastia/efectos adversos , Angioplastia/instrumentación , Estenosis Carotídea/terapia , Hemodinámica , Stents , Accidente Cerebrovascular/etiología , Anciano , Angioplastia/mortalidad , Antiarrítmicos/uso terapéutico , Presión Sanguínea , Estenosis Carotídea/complicaciones , Estenosis Carotídea/mortalidad , Estenosis Carotídea/fisiopatología , Bases de Datos Factuales , Femenino , Frecuencia Cardíaca , Hemodinámica/efectos de los fármacos , Humanos , Tiempo de Internación , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Accidente Cerebrovascular/mortalidad , Accidente Cerebrovascular/fisiopatología , Accidente Cerebrovascular/prevención & control , Factores de Tiempo , Resultado del Tratamiento , Estados Unidos
5.
Phys Chem Chem Phys ; 21(18): 9538-9546, 2019 May 08.
Artículo en Inglés | MEDLINE | ID: mdl-31020981

RESUMEN

A model is introduced for treating early-stage nucleation, growth kinetics, and mesoscale domain structure in submonolayer polycrystalline films prepared by solution-phase processing methods such as spin casting, dip coating, liquid-based printing, and related techniques. The model combines a stochastic treatment of nucleation derived from classical nucleation theory with deterministic computation of the spatiotemporal dynamics of the monomer concentration landscape by numerical solution of the two-dimensional diffusion equation, treating nuclei as monomer sinks. Results are compared to experimental measurements of solution-processed submonolayer tetracene films prepared using a vapor-liquid-solid deposition technique. Excellent agreement is observed with most major kinetic and structural film characteristics, including the existence of distinct induction, nucleation, and growth regimes, the onset time for nucleation, the number of domains formed per unit area, and the micron- to millimeter-scale spacing statistics of those domains. The model also provides a detailed description the dynamically-evolving monomer concentration landscape during film formation as well as quantities derived from it, such as time- and position-dependent domain nucleation and growth rates.

8.
Phys Chem Chem Phys ; 20(1): 694, 2017 12 20.
Artículo en Inglés | MEDLINE | ID: mdl-29218348

RESUMEN

Correction for 'A simple model of burst nucleation' by Alexandr Baronov et al., Phys. Chem. Chem. Phys., 2015, 17, 20846-20852.

11.
Ann Surg Oncol ; 23(4): 1371-9, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26661409

RESUMEN

BACKGROUND: Without prospective data establishing a consensus multimodality approach to borderline resectable pancreatic adenocarcinoma, institutional treatment regimens vary. This study investigated the outcomes of the clinical pathway at the author's institution, which consists of neoadjuvant gemcitabine, docetaxel, capecitabine, and stereotactic radiotherapy followed by surgery. METHODS: The study reviewed all cases that met the National Comprehensive Cancer Network (NCCN) diagnostic criteria for borderline resectable pancreatic adenocarcinoma from 1 January 2006, to 31 December 2013. Pancreatectomy rates, margin status, pathologic response, disease-free survival (DFS), disease-specific survival (DSS), and overall survival (OS) were retrospectively examined. Standard statistical methods and Kaplan-Meier survival analysis were used for statistical comparisons. RESULTS: Of 121 patients who met criteria, 101 entered the clinical pathway, and 94 (93.1 %) completed neoadjuvant chemotherapy and radiation therapy. Of the 101 patients, 55 (54.5 %) underwent pancreatectomy, with 53 patients (96.4 %) having microscopically negative margins (R0) and 2 patients (3.6 %) having microscopically positive margins (R1). Vascular resection was required for 22 patients (40 %), with rates of 95.5 % for R0 (n = 21) and 4.5 % for R1 (n = 1). A pathologic response to treatment was demonstrated by 45 patients (81.8 %) and a complete response by 10 patients (14.5 %). Pancreatectomy resulted in a median DFS of 23 months (95 % conflidence interval [CI] 14.5-31.5), a median DSS of 43 months (95 % CI, 25.7-60.3), and a median OS of 33 months (95 % CI, 25.0-41.0) versus a median DSS and OS of 14 months (95 % CI, 10.9-17.1) for patients without pancreatectomy (DSS: P = 3.5 × 10(-13); OS: P = 4.7 × 10(-10)). CONCLUSIONS: The study demonstrated high rates for neoajduvant therapy completion (93.1 %) and pancreatectomy (54.5 %). After pancreatectomy, DSS was significantly improved (43 months), with a pathologic response demonstrated by 81.8 % and a complete response by 14.5 % of the patients. The results support further study of this borderline resectable pancreatic adenocarcinoma clinical pathway.


Asunto(s)
Adenocarcinoma/patología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Vías Clínicas , Terapia Neoadyuvante , Pancreatectomía , Neoplasias Pancreáticas/patología , Radiocirugia , Adenocarcinoma/terapia , Anciano , Anciano de 80 o más Años , Capecitabina/administración & dosificación , Terapia Combinada , Desoxicitidina/administración & dosificación , Desoxicitidina/análogos & derivados , Docetaxel , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Neoplasias Pancreáticas/terapia , Pronóstico , Estudios Prospectivos , Estudios Retrospectivos , Tasa de Supervivencia , Taxoides/administración & dosificación , Gemcitabina
12.
Phys Chem Chem Phys ; 17(32): 20846-52, 2015 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-26214058

RESUMEN

We introduce a comprehensive quantitative treatment for burst nucleation (BN)-a kinetic pathway toward self-assembly or crystallization defined by an extended post-supersaturation induction period, followed by a burst of nucleation, and finally the growth of existing stable assemblages absent the formation of new ones-based on a hybrid mean field rate equation model incorporating thermodynamic treatment of the saturated solvent from classical nucleation theory. A key element is the inclusion of a concentration-dependent critical nucleus size, determined self-consistently along with the subcritical cluster population density. The model is applied to an example experimental study of crystallization in tetracene films prepared by organic vapor-liquid-solid deposition, where good agreement is observed with several aspects of the experiment using a single, physically well-defined adjustable parameter. The model predicts many important features of the experiment, and can be generalized to describe other self-organizing systems exhibiting BN kinetics.

13.
Ann Vasc Surg ; 28(1): 253-9, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24161440

RESUMEN

BACKGROUND: To determine whether the formation of an integrated vascular surgery residency (0 + 5) has negatively impacted the case volume and diversity of the vascular surgery fellows (5 + 2) and chief general surgeons at the same institution. METHODS: Operative data from the vascular integrated (0 + 5), independent (5 + 2), and general surgery residencies at a single institution were retrospectively reviewed and analyzed to determine vascular surgery case volumes from 2006-2012. National operative data (Residency Review Committee) were used for comparison of diversity and volume. Standard statistical methods were applied. RESULTS: During this period, the 5 + 2 fellows at our institution performed on average 741 (range, 554-1002) primary cases and 1091 (range, 844-1479) combined primary and secondary cases for the 2-year fellowship. Our integrated residency began in July 2007. Our fellows' primary case volumes remained relatively stable between 2006 and 2011, with a 4% increase in the number of cases, although their total (primary and secondary) case volumes fell 15%; by comparison, the equivalent national 50th percentile rates rose 16% during this time frame. Our institution's general surgery residents performed an average of 116 (range, 56-221) vascular cases individually during their 5-year residency from 2005-2011. From 2006-2011, the total case volume fell only 5%, while the national 50th percentile rate fell 24%. Across all years, however, resident and fellow volumes both continue to be above Accreditation Council for Graduate Medical Education minimum requirements, and the major vascular case volume at our institution in all groups studied remained statistically greater than or equal to the national 50th percentile of cases. Our first integrated resident to graduate finished in June 2012 with 931 total vascular cases and 249 general surgery cases for a total operative experience of 1180 cases during the 5-year residency. Finally, after an 8-year period (2003-2010) in which none of our general surgery residents pursued vascular training, 1 resident in each of the 2011, 2012, and 2013 graduating years has now done so. CONCLUSIONS: At our institution, the introduction of a 0 + 5 vascular residency has correlated with a modest drop (15%) in overall case volume for the 5 + 2 fellows, but the number of primary cases have actually increased slightly and they continue to meet or exceed Accreditation Council for Graduate Medical Education requirements and national 50th percentile rates. General surgery residents' vascular volumes, by contrast, have remained stable, and interest in vascular surgery by residents has increased. Our integrated vascular residents are projected to exceed the fellows' 50th percentile case volume and diversity targets during their residency experience.


Asunto(s)
Educación de Postgrado en Medicina/métodos , Becas , Cirugía General/educación , Internado y Residencia , Procedimientos Quirúrgicos Vasculares/educación , Carga de Trabajo , Acreditación , Certificación , Competencia Clínica , Curriculum , Educación de Postgrado en Medicina/normas , Educación de Postgrado en Medicina/estadística & datos numéricos , Becas/normas , Becas/estadística & datos numéricos , Florida , Cirugía General/normas , Cirugía General/estadística & datos numéricos , Humanos , Internado y Residencia/normas , Internado y Residencia/estadística & datos numéricos , Estudios Retrospectivos , Factores de Tiempo , Procedimientos Quirúrgicos Vasculares/normas , Procedimientos Quirúrgicos Vasculares/estadística & datos numéricos , Carga de Trabajo/normas , Carga de Trabajo/estadística & datos numéricos
14.
J Surg Res ; 157(2): 223-6, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19560786

RESUMEN

OBJECTIVES: To evaluate the efficacy of antibiotic-impregnated polymethylmethacrylate (PMMA) beads in eradication of an arterial prosthetic graft methicillin-resistant Staphylococcus aureus (MRSA) biofilm in an experimental animal model. METHODS: Forty rats underwent subcutaneous implantation of a MRSA-colonized arterial polytetrafluoroethylene (PTFE) 1 x 1 cm wafer on the back. The effect of regional antibiosis produced by antibiotic PMMA bead placement adjacent to the infected PTFE wafer was determined using four 10-animal study groups: control (no antibiotic), PMMA bead with no antibiotic, PMMA bead with 10% vancomycin, and PMMA bead with 10% daptomycin. After 3 d, the PTFE wafers were explanted and quantitative biofilm cultures, expressed as colony-forming units (CFU) per graft wafer, performed using real-time polymerase chain reaction to assess MRSA eradication. No systemic antibiotic was administered. Bioassays of antibiotic bead bacteriocidal were performed by measuring zone of inhibition diameters on MRSA colonized agar culture plates prior to and following graft explantation. RESULTS: All animal tolerated implantation of the MRSA-infected PTFE wafer and survived the 3 d until graft explantation. Quantitative biofilm cultures demonstrated a significant decrease (P < 0.01) in MRSA CFUs present on the PTFE wafer surfaces in the presence of both the vancomycin- and daptomycin-impregnated beads compared to controls and plain PMMA beads. Both vancomycin and daptomycin PMMA beads retained antibacterial activity after 3 d of implantation with decrease in zones of inhibition of 15% and 45%, respectively. CONCLUSIONS: Regional antibiotic delivery using an antibiotic-impregnated PMMA bead reduced the bacterial biofilm concentration in experimental subcutaneous pocket model of vascular surgical site infection. The delivery of antibiotics via a PMMA bead may be a useful adjunct in the treatment of vascular surgical site infection.


Asunto(s)
Antibacterianos/administración & dosificación , Antibacterianos/uso terapéutico , Sistemas de Liberación de Medicamentos/métodos , Staphylococcus aureus Resistente a Meticilina , Infecciones Relacionadas con Prótesis/tratamiento farmacológico , Infecciones Estafilocócicas/tratamiento farmacológico , Animales , Biopelículas , Daptomicina/administración & dosificación , Daptomicina/uso terapéutico , Modelos Animales de Enfermedad , Masculino , Microesferas , Polimetil Metacrilato , Infecciones Relacionadas con Prótesis/microbiología , Ratas , Ratas Sprague-Dawley , Infecciones Estafilocócicas/microbiología , Resultado del Tratamiento , Vancomicina/administración & dosificación , Vancomicina/uso terapéutico
16.
Vasc Endovascular Surg ; 42(6): 537-44, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18782790

RESUMEN

The authors report the microbiology and outcomes following an individualized treatment algorithm for extracavitary (EC) prosthetic graft infection, including the use of graft preservation and in situ graft replacement techniques. A retrospective 8-year review of 87 patients treated for EC prosthetic graft infections was carried out. The treatment algorithm included culture-specific antibiotic therapy, surgical site debridement with antibiotic bead placement, selected graft preservation with muscle flap coverage, or graft excision with in situ conduit replacement. Outcomes measured included death, limb loss, and recurrent infection. It was found that present-day management of EC prosthetic graft infections is associated with lower mortality and morbidity despite changes in microbiology and the increased application of graft preservation and in situ grafting treatments.


Asunto(s)
Implantación de Prótesis Vascular/efectos adversos , Prótesis Vascular/efectos adversos , Infecciones Relacionadas con Prótesis/microbiología , Infecciones Relacionadas con Prótesis/terapia , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Amputación Quirúrgica , Antibacterianos/uso terapéutico , Implantación de Prótesis Vascular/instrumentación , Terapia Combinada , Desbridamiento , Remoción de Dispositivos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infecciones Relacionadas con Prótesis/mortalidad , Recurrencia , Reoperación , Estudios Retrospectivos , Colgajos Quirúrgicos , Factores de Tiempo , Resultado del Tratamiento
17.
J Vasc Surg ; 48(3): 613-8, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18639428

RESUMEN

OBJECTIVE: Controversy regarding the efficacy of duplex ultrasound surveillance after infrainguinal vein bypass led to an analysis of patient and bypass graft characteristics predictive for development of graft stenosis and a decision of secondary intervention. METHODS: Retrospective analysis of a contemporary, consecutive series of 353 clinically successful infrainguinal vein bypasses performed in 329 patients for critical (n = 284; 80%) or noncritical (n = 69; 20%) limb ischemia enrolled in a surveillance program to identify and repair duplex-detected graft stenosis. Variables correlated with graft stenosis and bypass repair included: procedure indication, conduit type (saphenous vs nonsaphenous vein; reversed vs nonreversed orientation), prior bypass graft failure, postoperative ankle-brachial index (ABI) < 0.85, and interpretation of the first duplex surveillance study as "normal" or "abnormal" based on peak systolic velocity (PSV) and velocity ratio (Vr) criteria. RESULTS: Overall, 126 (36%) of the 353 infrainguinal bypasses had 174 secondary interventions (endovascular, 100; surgery, 74) based on duplex surveillance; resulting in 3-year Kaplan-Meier primary (46%), assisted-primary (80%), and secondary (81%) patency rates. Characteristics predictive of duplex-detected stenosis leading to intervention (PSV: 443 +/- 94 cm/s; Vr: 8.6 +/- 9) were: "abnormal" initial duplex testing indicating moderate (PSV: 180-300 cm/s, Vr: 2-3.5) stenosis (P < .0001), non-single segment saphenous vein conduit (P < .01), warfarin drug therapy (P < .01), and redo bypass grafting (P < .001). Procedure indication, postoperative ABI level, statin drug therapy, and vein conduit orientation were not predictive of graft revision. The natural history of 141 (40%) bypasses with an abnormal first duplex scan differed from "normal" grafts by more frequent (51% vs 24%, P < .001) and earlier (7 months vs 11 months) graft revision for severe stenosis and a lower 3-year assisted primary patency (68% vs 87%; P < .001). In 52 (15%) limbs, the bypass graft failed and 20 (6%) limbs required amputation. CONCLUSIONS: The efficacy of duplex surveillance after infrainguinal vein bypass may be enhanced by modifying testing protocols, eg, rigorous surveillance for "higher risk" bypasses, based on the initial duplex scan results and other characteristics (warfarin therapy, non- single segment saphenous vein conduit, redo bypass) predictive for stenosis development.


Asunto(s)
Extremidades/irrigación sanguínea , Oclusión de Injerto Vascular/diagnóstico por imagen , Isquemia/cirugía , Vena Safena/trasplante , Ultrasonografía Doppler Dúplex , Grado de Desobstrucción Vascular , Procedimientos Quirúrgicos Vasculares , Anticoagulantes/efectos adversos , Femenino , Oclusión de Injerto Vascular/etiología , Oclusión de Injerto Vascular/fisiopatología , Oclusión de Injerto Vascular/cirugía , Humanos , Isquemia/diagnóstico por imagen , Isquemia/fisiopatología , Masculino , Cuidados Posoperatorios , Reoperación , Estudios Retrospectivos , Factores de Riesgo , Factores de Tiempo , Insuficiencia del Tratamiento , Procedimientos Quirúrgicos Vasculares/efectos adversos , Warfarina/efectos adversos
18.
J Vasc Surg ; 46(6): 1160-6, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17920227

RESUMEN

BACKGROUND: We sought to describe modes of failure and associated limb loss after infrainguinal polytetrafluoroethylene bypass grafting in patients lacking a saphenous venous conduit and to define specific clinical or hemodynamic factors prognostic for bypass failure. METHODS: We identified 121 patients (mean age, 67 years; 90 men and 31 women) with determinable outcomes (minimum follow-up, 2 months; mean, 17 months) after 130 prosthetic infrainguinal bypasses between 1997 and 2005. Ischemic presentation was rest pain in 52%, tissue loss in 34%, and disabling claudication and/or popliteal aneurysm in 14%, with 24% of patients requiring a redo bypass. Distal targets were the above-knee (n = 44), distal popliteal (n = 27), or tibial/pedal (n = 59) arteries. Sixty-six (77%) of the below-knee (BK) target (distal popliteal or tibial) bypasses had distal anastomotic adjuncts (vein cuff or patch). Duplex graft surveillance was performed at 1, 4, and 7 months after surgery and twice yearly thereafter, with recording of midgraft velocities and imaging encompassing inflow and outflow vessels. Arteriography and open/endovascular intervention was performed for stenoses identified by duplex scanning (peak systolic velocity >300 cm/s; velocity ratio >3.5). An attempt was made to salvage occluded grafts by using catheter-directed thrombolysis or open techniques. Eighty-six patients (74% of BK bypasses) were placed on chronic warfarin therapy with a target international normalized ratio range between 2 and 3. Prognostic factors were identified by using univariate statistics and multivariate logistic regression analysis. RESULTS: Three-year primary, assisted, and secondary patency rates were 39%, 43%, and 59%, respectively, for all bypasses, with no difference noted between above-knee and BK grafts (P = .5). At 3 years, freedom from limb loss was 75%, and patient survival was only 70%, with no adverse effect on survival imparted by amputation. Sixty-nine total adverse events occurred as a result of thrombotic occlusion (n = 51), duplex scan-detected stenosis (n = 13), or graft infection (n = 5). Forty-nine percent of all initial graft occlusions eventually led to amputation. Twenty-three grafts (27% of 86 patients) in patients maintained on chronic warfarin were subtherapeutic at the time of occlusion. Use of a distal anastomotic adjunct with BK bypasses reduced graft thrombosis (35% with vs 60% without) but did not impart a significant patency advantage (P = .07). Multivariate analysis revealed low graft flow (midgraft velocity < or =45 cm/s; odds ratio [OR], 6.1; 95% confidence interval [CI], 1.9-19.2), use of warfarin (OR, 8.4; 95% CI, 2.1-34.5), and therapeutic warfarin (OR, 24.6; 95% CI, 5.7-106) to be independently predictive for bypass patency. Graft patency was maintained in 89% of grafts remaining therapeutic on warfarin compared with only 55% of subtherapeutic or nonanticoagulated grafts (P < .001). Low-flow grafts (n = 61) occluded more frequently than higher-flow grafts (46% vs 13%; P < .001). Therapeutic warfarin augmented the patency of low-flow (P < .001) but not high-flow (P = .15) grafts. CONCLUSIONS: Low graft flow was a more common mode of prosthetic bypass failure than development of duplex scan-detected stenotic lesions during follow-up. Early duplex scanning may be more important for characterizing midgraft velocity and related thrombotic potential and selecting patients for chronic anticoagulation. Maintenance of therapeutic warfarin is paramount in optimizing prosthetic bypass patency and limb preservation.


Asunto(s)
Anticoagulantes/uso terapéutico , Implantación de Prótesis Vascular/efectos adversos , Prótesis Vascular , Oclusión de Injerto Vascular/prevención & control , Isquemia/cirugía , Extremidad Inferior/irrigación sanguínea , Trombosis/prevención & control , Ultrasonografía Doppler Dúplex , Warfarina/uso terapéutico , Anciano , Anciano de 80 o más Años , Amputación Quirúrgica , Implantación de Prótesis Vascular/instrumentación , Femenino , Estudios de Seguimiento , Oclusión de Injerto Vascular/diagnóstico por imagen , Oclusión de Injerto Vascular/etiología , Oclusión de Injerto Vascular/fisiopatología , Humanos , Isquemia/diagnóstico por imagen , Isquemia/mortalidad , Isquemia/fisiopatología , Recuperación del Miembro , Modelos Logísticos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Selección de Paciente , Politetrafluoroetileno , Diseño de Prótesis , Falla de Prótesis , Flujo Sanguíneo Regional , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Trombosis/diagnóstico por imagen , Trombosis/etiología , Trombosis/fisiopatología , Factores de Tiempo , Insuficiencia del Tratamiento , Grado de Desobstrucción Vascular
19.
J Vasc Surg ; 46(3): 460-5; discussion 465-6, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17681713

RESUMEN

OBJECTIVE: A duplex ultrasound (DUS) surveillance algorithm used after carotid endarterectomy (CEA) was applied to patients after carotid stenting and angioplasty (CAS) to determine the incidence of high-grade stent stenosis, its relationship to clinical symptoms, and the outcome of reintervention. METHODS: In 111 patients who underwent 114 CAS procedures for symptomatic (n = 62) or asymptomatic (n = 52) atherosclerotic or recurrent stenosis after CEA involving the internal carotid artery (ICA), DUS surveillance was performed 300 cm/s, diastolic velocity >125 cm/s, internal carotid artery stent/proximal common carotid artery ratio >4) involving the stented arterial segment prompted diagnostic angiography and repair when >75% diameter-reduction stenosis was confirmed. Criteria for >50% CAS stenosis was a PSV >150 cm/s with a PSV stent ratio >2. RESULTS: All 114 carotid stents were patent on initial DUS imaging, including 90 (79%) with PSV <150 cm/s (94 +/- 24 cm/s), 23 (20%) with PSV >150 cm/s (183 +/- 34 cm/s), and one with high-grade, residual stenosis (PSV = 355). During subsequent surveillance, 81 CAS sites (71%) exhibited no change in stenosis severity, nine sites demonstrated stenosis regression to <50% diameter reduction, and five sites developed velocity spectra of a high-grade stenosis. Angiography confirmed >75% diameter reduction in all six CASs with DUS-detected high-grade stenosis, all patients were asymptomatic, and treatment consisted of endovascular (n = 5) or surgical (n = 1) repair. During the mean 33-month follow-up period, three patients experienced ipsilateral, reversible neurologic events at 30, 45, and 120 days after CAS; none was associated with severe stent stenosis. No stent occlusions occurred, and no patient with >50% CAS stenosis on initial or subsequent testing developed a permanent ipsilateral permanent neurologic deficit or stroke-related death. CONCLUSION: DUS surveillance after CAS identified a 5% procedural failure rate due to the development of high-grade in-stent stenosis. Both progression and regression of stent stenosis severity was observed on serial testing, but 70% of CAS sites demonstrated velocity spectra consistent with <50% diameter reduction. The surveillance algorithm used, including reintervention for asymptomatic high-grade CAS stenosis, was associated with stent patency and the absence of disabling stroke.


Asunto(s)
Implantación de Prótesis Vascular/métodos , Estenosis Carotídea/cirugía , Endarterectomía Carotidea/métodos , Oclusión de Injerto Vascular/diagnóstico por imagen , Ultrasonografía Doppler Dúplex , Anciano , Anciano de 80 o más Años , Velocidad del Flujo Sanguíneo/fisiología , Estenosis Carotídea/diagnóstico por imagen , Femenino , Oclusión de Injerto Vascular/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Pronóstico , Índice de Severidad de la Enfermedad
20.
J Vasc Surg ; 46(1): 71-8, 2007 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-17606124

RESUMEN

BACKGROUND: The complexity of variables associated with vascular surgical site infections (VSSI) often contribute adversely to reinfection, limb salvage, and mortality rates. This report details our experience with the selective use of a sartorius muscle flaps (SMF) as part of an overall treatment strategy focused on staged surgical debridement (SSD) to control prosthetic graft bed infection prior to a graft preservation or revision plan. METHODS: From our vascular registry, we identified 422 VSSI of which 89 (21%) had SMF for 24 aorto-bifemoral (ABF), 19 extra-anatomic bypasses (EAB), 34 infrainguinal bypasses, and 12 combined inflow/outflow reconstructions. All 86 patients had Szilagyi grade III prosthetic (Dacron-36, polytetrafluoroethylene [PTFE]-50) graft infections. The treatment algorithm included: SSD, culture-directed parenteral antibiotics, graft preservation (n = 3), or reconstruction (graft excision/EAB, n = 4; rifampin-bonded PTFE, n = 22; autologous conduit, n = 57) based on microbiology and consideration for SMF for extensive soft tissue defects (n = 43) or non-sterilized graft beds (n = 40). Analysis of microbiology, recurrent infection, vascular reconstruction, limb salvage, and mortality was completed over a mean follow-up of 52 months (range: 12 to 132 months). RESULTS: Thirty-day mortality was 2% with two aortic graft infections dying from sepsis. Survival by life table analysis at 1, 3, and 5 years was 94%, 92%, and 90%, respectively. Wound isolates were most commonly gram positive organisms (n = 58, 65%), with gram negative isolates and mixed infections accounting for 19% and 10%, respectively. A single recurrent groin infection was documented at 30 days. Freedom from recurrent infection (n = 6) at 1 and 5 years was 98% and 92% by life tables. Methicillin-resistant Staphylococcus aureus (MRSA) was involved for 50% of reinfections. No amputations were attributable to uncontrolled VSSI and graft patency was 100% in surveillance monitored patients. CONCLUSION: These results suggest that selective utilization of SMF as part of SSD treatment plan in an attempt to achieve graft bed sterilization can effectively control the complex infectious process allowing for potentially improved outcomes for in situ or preservation graft salvage techniques. Lifelong graft surveillance is recommended.


Asunto(s)
Implantación de Prótesis Vascular/instrumentación , Prótesis Vascular/efectos adversos , Desbridamiento , Infecciones Relacionadas con Prótesis/cirugía , Colgajos Quirúrgicos , Algoritmos , Árboles de Decisión , Femenino , Estudios de Seguimiento , Humanos , Tablas de Vida , Masculino , Músculo Esquelético/trasplante , Guías de Práctica Clínica como Asunto , Infecciones Relacionadas con Prótesis/microbiología , Infecciones Relacionadas con Prótesis/mortalidad , Recurrencia , Sistema de Registros , Estudios Retrospectivos , Índice de Severidad de la Enfermedad , Factores de Tiempo , Resultado del Tratamiento
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