ERASMO SIMAO DA SILVA
Projetos de Pesquisa
Unidades Organizacionais
Departamento de Cirurgia, Faculdade de Medicina - Docente
LIM/02 - Laboratório de Anatomia Médico-Cirúrgica, Hospital das Clínicas, Faculdade de Medicina - Líder
LIM/02 - Laboratório de Anatomia Médico-Cirúrgica, Hospital das Clínicas, Faculdade de Medicina - Líder
7 resultados
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- Left Common Carotid Artery Biomechanical Properties in Individuals over 80 years: Women Have Stiffer Vessels(2020) GOMES, Vivian Carla; SILVA, Luiz Fernando da; ZYNGIER, Selene Perrotti; SILVESTRE, Gina Camillo; QUEIROZ, Alexandre; MARQUES, Michele Alberto; SILVA, Erasmo Simao daBackground: Considering the longevity of the worldwide population, the cardiovascular diseases deserve particular attention, especially the carotid artery disease in the >= 80-year-old population. The stiffness of the common carotid artery, for example, has been showed in numerous clinical studies as a marker of increased risk of stroke, dementia, and depression. Besides, with the emergence of new surgical techniques such as the transcarotid artery revascularization that uses the common carotid artery as a workstation, the biomechanical and histological features of this vessel, more than ever, must be detailed. Methods: Left common carotid artery fragments from 9 cadaver donors (>= 80 years old) were evaluated. Biomechanical (failure stress, tension, and strain) and histological (percentage of collagen and elastic fibers) features of these samples were analyzed with special focus on gender differences. Results: Statistically significant differences in biomechanical and histological features between the genders were observed. The percentage of collagen fiber in intima (P = 0.008) and media (P = 0.041) layers was significantly lower in men than in women. A higher elasticity (failure strain) of the specimens in male gender was also observed (P = 0.025). No significant difference was observed in the layers thickness between the genders regardless which part of the arterial wall was considered. Conclusions: These biomechanical and histological findings could be the responsible for the higher left common carotid artery stiffness observed among >80-year-old women when compared with men in numerous clinical studies in literature.
- Biomechanical Analysis of Cadaveric Thoracic Aorta Zones: The Isthmus is the Weakest Region(2021) GOMES, Vivian Carla; SILVESTRE, Gina Camillo; QUEIROZ, Alexandre; MARQUES, Michele Alberto; LEAO, Pedro Puech; SILVA, Erasmo Simao daBackground: The thoracic aorta is a site of multiple pathological processes, such as aneurysms and dissections. When considering the development of endovascular devices, this vessel has been extensively manipulated because of aortic diseases, as well as to serve as a route for procedures involving the head and neck vessels. Therefore, the aim of the present study was to obtain biomechanical experimental information about the strength and deformability of this vessel. Materials and Methods: Thirty-one thoracic aorta specimens were harvested during the autopsy procedure. They were carefully dissected and transversally sectioned according to Criado's aortic arch map landing zones (0 to 4). The supra-aortic trunks were removed, and the aortic rings were opened in their convexity, which resulted in flat tissue segments. Four millimeter-wide strips were prepared from each zone after which they were attached to a clip system connected to the INSTRON SPEC 2200 device, which was responsible for pulling the fragment up to its rupture during the uniaxial tension test. The INSPEC software was used to coordinate the test, and data management was conducted via the SERIES IX software. The biomechanical variables that were measured included failure stress, failure tension, and failure strain. Results: When comparing the five segments from all 31 aortas, three different strength levels were observed. Zones 0 and 1 exhibited the highest failure stress and failure tension values, followed by Zones 2 and 4. Zone 3 (aortic isthmus) was the weakest segment that was tested when compared to the stress and tension of Zones 0 and 1 (P < 0.001), the stress and tension of Zone 2 (P = 0.005 and P = 0.002, respectively) and the stress and tension of Zone 4 (P = 0.023 and P = 0.006, respectively). Among donors > 65 years-old, women presented significantly weaker descending aortas than men in regards to stress (P = 0.049) and tension (P = 0.014). Among male donors, the elderly donors presented significantly stiffer aortic walls and weaker ascending (P = 0.029 for stress) and descending (P = 0.004 for stress; P = 0.031 for tension) aortas than younger men. Conclusions: Uniaxial tensile strength tests revealed that the thoracic aorta is a very heterogeneous vessel. Isthmus frailty may add to the understanding of the pathophysiology of some aortic diseases that commonly compromise this region. The lower strength that was verified in some aortic segments from elderly donors may contribute to the genesis of some thoracic aorta diseases among that group of donors. These data can contribute to the development of new endovascular devices that are specifically designed for this vessel.
- Biomechanical and histological data from abdominal aortas harvested in autopsy(2021) GOMES, Vivian Carla; SILVA, Luiz Fernando Ferraz da; RAGHAVAN, Madhavan Lakshmi; GOMES, Jorge; SILVESTRE, Gina Camillo; QUEIROZ, Alexandre; MARQUES, Michele Alberto; ZYNGIER, Selene Perrotti; CHUNG, Timothy Kwang-Joon; SILVA, Erasmo Simao daThis data article describes biomechanical and histological information of abdominal aortas harvested in autopsy. Eight abdominal aorta aneurysms (AAA) and 30 normal diameter abdominal aortas were collected and submitted to an inflation test up to their rupture. This inflation procedure was part of the research entitled ?Experimental study of rupture pressure and elasticity of abdominal aortic aneurysms found at autopsy?, submitted to Annals of Vascular Surgery. The rupture borders and control samples (harvested from places other than the rupture site) were submitted to uniaxial destructive tensile test and to histological analysis. The following variables were evaluated in the biomechanical test: failure stress, failure tension and failure strain. The histological processing of the samples enabled a quantitative analysis of the percentage of coverage of collagen fibers and elastic fibers in the samples. The present data could be reutilized because they are experi-mental evidence that cadaveric abdominal aortas, even when previously stressed by inflation, conserve significant resis-tance against tearing comparable to no previously stressed aortas described in the literature. Considering real whole ca-daveric AAAs are especially scarce, this information would be a useful reference source for further in-depth research in the aortic biomechanics field. (C) 2021 The Authors.
- Aorta Rupture Assay: Comparing the Failure Pressure of Infrarenal Abdominal Aortic Aneurysm and Normal Abdominal Aorta Specimens(2019) GOMES, Vivian C.; RAGHAVAN, Madhavan L.; SILVA, Luiz F. da; ZYNGIER, Selene; SILVESTRE, Gina; QUEIROZ, Alexandre; MARQUES, Michele A.; SILVA, Erasmo S. da
- Experimental Study of Rupture Pressure and Elasticity of Abdominal Aortic Aneurysms Found at Autopsy(2021) GOMES, Vivian Carla; RAGHAVAN, Madhavan Lakshmi; SILVA, Luiz Fernando Ferraz da; GOMES, Jorge; SILVESTRE, Gina Camillo; QUEIROZ, Alexandre; MARQUES, Michele Alberto; ZYNGIER, Selene Perrotti; CHUNG, Timothy Kwang-Joon; SILVA, Erasmo Simao daBackground: Resistance and elasticity of normal and aneurysmal aorta walls are directly associated with this vessel's growth and rupture. This study aims to experimentally analyze the biomechanical behavior of aneurysmal specimens found at autopsy, comparing them with normal diameter aortas removed from age-matched donors. Methods: Thirty-eight human aortas (30 normal aortas; 8 infrarenal abdominal aortic aneurysms) were harvested during autopsy. An apparatus was built with a digital gauge, plastic tray, connections, and hoses that conducted fluid (air) from a pump through the system. Specimens were dissected, and a flexible balloon was introduced in each of them to avoid leakage. The specimens were fastened on the test tray, and activation of the air pump enhanced system pressure up to their rupture. Results: All 8 aneurysms and all 30 normal aortas specimens evolved to rupture under inflation pressures above 590 mm Hg (mean +/- standard deviation = 1,035 +/- 375 mm Hg) and 840 mm Hg (mean +/- SD = 1,405 +/- 342 mm Hg), respectively. In the aneurysm group, 25% of specimens did not rupture in their most dilated region. Percentage of increment in diameter was higher in normal aortas (mean +/- SD = 0.2106 +/- 0.144) than in aneurysms (mean +/- SD = 0.093 +/- 0.070). Conclusions: In the present experiment, unruptured infrarenal abdominal aortic aneurysms could support high pressures nearly as much as nonaneurysmal abdominal aortas. In some specimens, the most dilated part of the aneurysm was not the most vulnerable under pressure. Normal aortas presented higher elasticity than aneurysms.
- Biomechanics data of human supra-aortic trunks and abdominal visceral arteries harvested during autopsy(2020) GOMES, Vivian Carla; GOMES, Jorge; SILVESTRE, Gina Camillo; QUEIROZ, Alexandre; MARQUES, Michele Alberto; SILVA, Erasmo Simao daThe present dataset describes the biomechanical properties of the supra-aortic trunks (brachiocephalic trunk, left common carotid artery, and left subclavian artery) and some of the visceral branches of the abdominal aorta (celiac trunk, superior mesenteric artery, and renal arteries). The specimens have been harvested from 27 adult donors during the autopsy procedure. The vessels were submitted to uniaxial biomechanical tensile tests, and values of failure stress, failure tension, and failure strain were obtained. As atherosclerosis could affect any of those vessels producing a significant reduction in their lumen, the data presented here could be of great interest to vascular surgeons, interventional cardiologists, and interventional neuroradiologists, who manipulate these arteries endovascularly. The observations gathered here are experimental evidence of the vessels' endurance against tearing and of their deformability. Therefore this data article could also help the medical industry dedicated to the production of endovascular devices. This dataset is related to the article entitled ""Left Common Carotid Artery Biomechanical Properties in Individuals over 80 years: Women Have Stiffer Vessels"" published in Annals of Vascular Surgery in August 2020 [1]. (c) 2020 The Author(s).
- Biomechanical Properties of the Periaortic Abdominal Tissue: It is Not as Fragile as It Seems.(2021) GOMES, Vivian Carla; SILVA, Luiz Fernando Ferraz da; SILVESTRE, Gina Camillo; QUEIROZ, Alexandre; MARQUES, Michele Alberto; ZYNGIER, Selene Perrotti; SILVA, Erasmo Simao daBackground: The perivascular adipose tissue has been studied as a critical element that could influence physiological and disease processes of the vessel covered by it. In terms of anatomy, during the abdominal aorta?s dissection, it is possible to identify the periaortic adipose tissue and the periaortic parietal peritoneum lying over it, sealing the retroperitoneal space. They seem to be fragile layers, with apparently no biomechanical role in the abdomen. However, it is well known that most cases of ruptured abdominal aortic aneurysms (AAAs) that reach the emergency department still alive present retroperitoneal bleeding contained by the previously mentioned two-layer combination, eventually allowing time for surgical treatment. In previous studies about aortic wall stress, tension, and AAA rupture prediction, only information concerning the vessel wall itself is highlighted. Therefore, the present work aims to study the biomechanical and histological properties of the periaortic tissue, comparing them to the same variables measured in aortic wall samples described in the medical literature. Materials and Methods: Samples of periaortic tissue were harvested from 27 individuals during necropsy. Smoking status and the presence of AAAs were observed. Biomechanical uniaxial destructive tests were performed up to samples? rupture. Values of failure stress, tension, and strain were obtained. Samples were also harvested for histological analysis. Results: Periaortic tissue presented less amount of collagen in smokers than in nonsmokers (P 1/4 0.017). The periaortic tissue seems to be more elastic than aortic walls described in the literature (strain: 0.75 ? 0.37). Analyzing periaortic tissue failure stress (56.8 ? 101.26 N/cm2) and tension (7.65 ? 4.99 N/cm), it has at least 52% and 55%, respectively, of the stress and tension described in the medical literature for AAA walls. Conclusions: The periaortic tissue presents less collagen fibers in smokers than in nonsmokers. The periaortic tissue seemed very delicate during an autopsy, but the study of its biomechanical properties showed that it presents more than half of the resistance of an AAA wall. This information suggests this tissue might have a mechanical protective role against massive bleeding when it comes to an aortic rupture. Therefore this tissue?s biomechanical information should be included in computational models on enlargement and rupture prediction of AAAs.