Erasmo Simão da Silva

Biomechanical failure properties and microstructural content of ruptured and unruptured abdominal aortic aneurysms.

PURPOSE To test the hypothesis that ruptured abdominal aortic aneurysms (AAA) are globally weaker than unruptured ones. METHODS Four ruptured and seven unruptured AAA specimens were harvested whole from fresh cadavers during autopsies performed over an 18-month period. Multiple regionally distributed longitudinally oriented rectangular strips were cut from each AAA specimen for a total of 77 specimen strips. Strips were subjected to uniaxial extension until failure. Sections from approximately the strongest and weakest specimen strips were studied histologically and histochemically. From the load-extension data, failure tension, failure stress and failure strain were calculated. Rupture site characteristics such as location, arc length of rupture and orientation of rupture were also documented. RESULTS The failure tension, a measure of the tissue mechanical caliber was remarkably similar between ruptured and unruptured AAA (group mean ± standard deviation of within-subject means: 11.2±2.3 versus 11.6±3.6N/cm; p=0.866 by mixed model ANOVA). In post-hoc analysis, there was little difference between the groups in other measures of tissue mechanical caliber as well such as failure stress (95±28 versus 98±23 N/cm(2); p=0.870), failure strain (0.39±0.09 versus 0.36±0.09; p=0.705), wall thickness (1.7±0.4 versus 1.5±0.4mm; p=0.470) , and % coverage of collagen within tissue cross section (49.6±12.9% versus 60.8±9.6%; p=0.133). In the four ruptured AAA, primary rupture sites were on the lateral quadrants (two on left; one on left-posterior; one on right). Remarkably, all rupture lines had a longitudinal orientation and ranged from 1 to 6 cm in length. CONCLUSION The findings are not consistent with the hypothesis that ruptured aortic aneurysms are globally weaker than unruptured ones.

Aortoesophageal fistula caused by aneurysm of the thoracic aorta: Successful surgical treatment, case report, and literature review

Aortoesophageal fistula induced by atherosclerotic thoracic aortic aneurysm is rare, but is usually a fatal disorder, with few survivors reported. We report the case of a 72-year-old man with aortoesophageal fistula successfully treated in a two-stage operation. In the first stage, we performed resection and replacement of the aortic aneurysm with a prosthetic graft in situ, esophagectomy, cervical esophagostomy, and jejunostomy. After the patient recovered well postoperatively, a transmediastinal retrosternal interposition of the stomach was performed, with esophagogastroanastomosis in the cervical area, to re-establish the gastrointestinal tract. We include a discussion of the causes, diagnostic approach, management of the aorta and esophagus, and review of the literature.

Atenção integral ao portador de pé diabético

Sao apresentadas, nessa separata, as principais orientacoes sobre a atencao as complicacoes do pe diabetico. A neuropatia, com suas diversas apresentacoes que acometem os membros inferiores dos diabeticos, as lesoes da doenca arterial obstrutiva periferica (DAOP), as multiplas apresentacoes da infeccao do pe diabetico, e, principalmente, os cuidados preventivos que possam impedir o estabelecimento ou a evolucao dessas complicacoes sao tratados de forma sistematica e simplificada, visando a atencao integral desses doentes. Especial cuidado e dado as orientacoes diferenciadas para os diversos niveis de atencao nos servicos publicos de saude, porta de entrada virtual de 80% dos infelizes portadores dessa complicacao. Sao aqui apresentados modelos de atencao e sugeridos protocolos que podem contribuir para a efetiva reducao do numero de amputacoes, internacoes e obitos de diabeticos com complicacoes nos membros inferiores.

Primary aortoenteric fistula related to septic aortitis

CONTEXT Primary aortoenteric fistulas usually result from erosion of the bowel wall due to an associated abdominal aortic aneurysm. A few patients have been described with other etiologies such as pseudoaneurysm originating from septic aortitis caused by Salmonella. OBJECTIVE To present a rare clinical case of pseudoaneurysm caused by septic aortitis that evolved into an aortoenteric fistula. CASE REPORT A 65-year-old woman was admitted with Salmonella bacteremia that evolved to septic aortitis. An aortic pseudoaneurysm secondary to the aortitis had eroded the transition between duodenum and jejunum, and an aortoenteric fistula was formed. In the operating room, the affected aorta and intestinal area were excised and an intestine-to-intestine anastomosis was performed. The aorta was sutured and an axillofemoral bypass was carried out. In the intensive care unit, the patient had a cardiac arrest that evolved to death.

Histologic, histochemical, and biomechanical properties of fragments isolated from the anterior wall of abdominal aortic aneurysms

OBJECTIVE To analyze biomechanical, histologic, and histochemical properties of anterior fragments of abdominal aortic aneurysms (AAA) and to correlate them with the maximum transverse diameter (MTD) and symptoms associated to the aneurysms. METHODS Fragments of the anterior aneurysm wall were obtained from 90 patients submitted to open repair of AAA of degenerative etiology from 2004 to 2009 in the Clinics Hospital of São Paulo University Medical School. Two specimens were produced from the fragments: one for histologic analysis for quantification of collagen fibers, elastic fibers, smooth muscle cells, and degree of inflammatory activity and the other for uniaxial tensile test to assess biomechanical failure properties of the material, such as strength, tension, and stress. Cases were classified according to symptoms and to the AAA MTD. RESULTS Fragments from AAA with MTD < 5.5 cm showed higher values for biomechanical failure properties than those of AAA with MTD < 5.5 cm (strength, 5.32 ± 2.07 × 4.1 ± 2.41 N; tension, 13.83 ± 5.58 × 10.82 ± 6.48 N/cm; stress, 103.02 × 77.03 N/cm(2); P < .05). No differences were observed between the groups in relation to failure strain (0.41 ± 0.12 × 0.37 ± 0.14; P = .260) and thickness of the fragments (1.58 ± 0.41 × 1.53 ± 0.42 mm; P = .662). The average values of fiber compositions of all the fragments were as follows: collagen fibers, 44.34 ± 0.48% and 61.85 ± 10.14% (Masson trichrome staining and Picrosirius red staining, respectively); smooth muscle cells, 3.46 ± 2.23% (immunohistochemistry/alpha-actin); and elastic fibers, less than 1% (traces) (Verhoeff-van Gieson staining). No differences in fiber percentages (collagen, elastic, and smooth muscle) were observed in fragments from AAA with MTD <5.5 cm and <5.5 cm, but more intense inflammatory activity was seen in larger AAA (grade 3; 70% × 28.6%; P = .011). Compared with asymptomatic aneurysms, symptomatic aneurysms showed no differences in the biomechanical failure properties (strength, 5.32 ± 2.36 × 4.65 ± 2.05 N; P = .155; tension, 14.08 ± 6.11 × 12.81 ± 5.77 N/cm; P = .154; stress, 103.02 × 84.76 N/cm(2); P = .144), strain (0.38 ± 0.12 × 0.41 ± 0.13; P = .287), thickness of the fragments (1.56 ± 0.41 × 1.57 ± 0.41 mm; P = .848), and histologic composition (collagen fibers, 44.67 ± 11.17 × 44.02 ± 13.79%; P = .808; smooth muscle fibers, 2.52 × 2.35%; P = .751; elastic fibers, <1%) CONCLUSIONS Fragments of the anterior wall from larger aneurysms were more resistant than those from smaller AAA, with no tissue properties that could explain this phenomenon in the histologic or histochemical analyses utilized. CLINICAL RELEVANCE The fragments of the anterior midsection from larger aneurysms were more resistant than those from smaller abdominal aortic aneurysms, with no tissue properties that could explain this phenomenon in the histologic or histochemical analyses. Larger aneurysms, at least in this place may be stronger than smaller aneurysms. It could point toward regional differences (heterogeneity, localized pathologies) as an important player in aneurysm rupture. Uniaxial strain tests are an important tool for the comprehension of a complex behavior such as that from an aneurysmal aortic wall. However, these tests still have limitations in providing information that would allow the calculation of the risk of rupture for abdominal aortic aneurysms.

Short-lasting systemic and regional benefits of early crystalloid infusion after intravenous inoculation of dogs with live Escherichia coli

We investigated the systemic and regional hemodynamic effects of early crystalloid infusion in an experimental model of septic shock induced by intravenous inoculation with live Escherichia coli. Anesthetized dogs received an intravenous infusion of 1.2 x 10(10) cfu/kg live E. coli in 30 min. After 30 min of observation, they were randomized to controls (no fluids; N = 7), or fluid resuscitation with lactated Ringers solution, 16 ml/kg (N = 7) or 32 ml/kg (N = 7) over 30 min and followed for 120 min. Cardiac index, portal blood flow, mean arterial pressure, systemic and regional oxygen-derived variables, blood lactate, and gastric PCO2 were assessed. Rapid and progressive cardiovascular deterioration with reduction in cardiac output, mean arterial pressure and portal blood flow (approximately 50, approximately 25 and approximately 70%, respectively) was induced by the live bacteria challenge. Systemic and regional territories showed significant increases in oxygen extraction and in lactate levels. Significant increases in venous-arterial (approximately 9.6 mmHg), portal-arterial (approximately 12.1 mmHg) and gastric mucosal-arterial (approximately 18.4 mmHg) PCO2 gradients were also observed. Early fluid replacement, especially with 32 ml/kg volumes of crystalloids, promoted only partial and transient benefits such as increases of approximately 76% in cardiac index, of approximately 50% in portal vein blood flow and decreases in venous-arterial, portal-arterial, gastric mucosal-arterial PCO2 gradients (7.2 +/- 1.0, 7.2 +/- 1.3 and 9.7 +/- 2.5 mmHg, respectively). The fluid infusion promoted only modest and transient benefits, unable to restore the systemic and regional perfusional and metabolic changes in this hypodynamic septic shock model.

Impact of stent-graft oversizing on the thoracic aorta: experimental study in a porcine model.

Purpose To analyze in an experimental animal model the effect of 4 different levels of stents-graft oversizing on non-atherosclerotic aortas such as those found in young individuals who undergo stent-graft repair for traumatic aortic injuries. Methods The diameter of the porcine thoracic aorta is similar to the aorta of young adults (18–20 mm), so 25 pigs were randomized into 5 groups: 1 control (without stent-graft) and 4 oversizing groups (A: 10%–19%, B: 20%–29%, C: 30%–39%, and D: >40%). Two types of biomechanical tests were performed on all aortas 4 weeks after endoprosthesis deployment. Results The results of the detachment test, which analyzed the strength necessary to remove the stent-graft from the aorta, were similar in the 4 groups (A: 42 N, B: 41 N, C: 46 N, and D: 46 N). However, 2 aortas ruptured during the tests (groups C and D). The second test was performed in 3 aortic segments. Maximum shear strength, maximum stress, and maximum tension supported by the aortic wall had a negative and linear correlation with oversizing. There were significant differences in all 4 groups when compared with the control group. Strain, which reflects the elastic properties of the aortic wall, was very similar in all 4 groups, but a great difference was found when compared with the control group (p<0.0001). Conclusion The study showed an important subacute change in the biomechanical properties of the aortic wall after implantation of an oversized endoprosthesis. This weakness of the aortic wall was confirmed by 2 ruptures during the detachment test. These results partially explain the interaction of stent-grafts with non-atherosclerotic thoracic aortas and may serve as a basis for further studies and the development of specific material to be used in vascular trauma and young patients.

Doença arterial obstrutiva periférica: que atenção temos dispensado à abordagem clínica dos pacientes?

OBJETIVO: Avaliar como pacientes com doenca arterial obstrutiva periferica tem sido tratados, em nosso meio, com relacao aos fatores de risco e comorbidades. METODO: Questionario sobre pesquisa e tratamento da dislipidemia, diabetes, exercicio, uso de anti-plaquetarios, tabagismo e hipertensao arterial no paciente com doenca arterial obstrutiva periferica foi aplicado entre os medicos presentes na reuniao mensal de marco de 2004 da Sociedade Brasileira de Angiologia e Cirurgia Vascular - Regional Sao Paulo. RESULTADOS: Dos 102 questionarios distribuidos, 75 foram respondidos (taxa de resposta de 73,5%). Entre os consultados, 82% pesquisam rotineiramente perfil lipidico e 20% visam alvo de LDL-colesterol abaixo de 100 mg/dl; 94% realizam pesquisa para diabetes melito; 97% recomendam exercicio; 79% prescrevem aspirina; 97% aconselham que os pacientes parem de fumar e 60% se restringem ao aconselhamento isoladamente; 18% nao realizam a medida da pressao arterial durante a consulta e 19% visam alvo pressorico de 130 x 80 mmHg. Considerando todas as avaliacoes em conjunto - intervencao no estilo de vida, no sentido de parar de fumar, orientacao de exercicios, uso de anti-plaquetarios, realizacao de pesquisa para diabetes melito, controle rigoroso da pressao arterial e lipides - observou-se que 7% dos entrevistados seguem todas essas recomendacoes como uma rotina estabelecida. CONCLUSAO: O presente estudo demonstrou que, em nosso meio, a pesquisa e o tratamento dos fatores de risco e comorbidades nos pacientes com doenca arterial obstrutiva periferica estao sendo sub-realizados.

Endovascular and open repair for blunt aortic injury, treated in one clinical institution in Brazil: a case series

OBJECTIVE The objective of this retrospective study is to analyze and compare the results of conventional surgical repair and endovascular treatment of blunt aortic injury over the past 8 years. METHODS Twenty-eight patients (25 male; mean age, 35 years) were treated for blunt aortic injury between April 2001 and March 2009 in a university hospital in Brazil. Twenty-six patients were included in the study: five were treated with operative repair (OR) and 21 with endovascular treatment (TEVAR). Two patients were excluded from analysis: one was managed conservatively, and one was treated with endovascular treatment for chronic dissection related to aortic trauma. RESULTS Mean age was lower in the OR group than in the endovascular treatment group (17.8 vs. 38 years, P = .003). There was one death in the OR group and four deaths in the endovascular treatment group. Mean follow-up for the overall group was 33.6 months, with 48.7 months (range 8-83 months) for the OR group, and 29.8 months (range 2-91 months) for the TEVAR group. Mean time elapsed from injury to repair was 23.4 hours (range 8-48 h, median 20 h) for the OR group and 30.3 hours (range 2-240 h, median 18 h) for the TEVAR group (P = .374). The duration of surgery was shorter in the endovascular treatment group (142 versus 237 minutes; P = .005). There were no significant differences with respect to the number of postoperative days requiring mechanical ventilation, duration of ICU stay or duration of hospital stay. CONCLUSION In this retrospective analysis, endovascular treatment was a safe method for repair of blunt aortic trauma, with immediate and midterm results that were comparable to those results obtained with operative repair. No complications from the stent graft were identified during follow-up. Nevertheless, long-term follow-up is necessary to confirm the effectiveness of this treatment.

Mandibular Subluxation for Distal Cervical Exposure of the Internal Carotid Artery

Introduction: Surgical access to the distal segment of the cervical internal carotid artery (ICA) is a challenge because of the limited exposure imposed by bony structures and concern regarding cranial nerve and major vasculature injury. Our objective is to quantify the additional exposure of the distal cervical ICA obtained with mandibular subluxation (MS) compared with maneuvers that do not mobilize the mandible.