The Distensibility of the Human Vena Cava and Its Importance to In Vitro Studies of Venous Compression Syndromes: A Search for a Suitable Polymer for 3-Dimensional Printing.

BACKGROUND: Venous compression syndromes are clinical conditions in which the large veins are compressed by other anatomical structures. Laboratory simulations may help us better understand the hemodynamics in venous compressions by creating situations similar to those seen in vivo. The aim of this study is to produce a model of the caval bifurcation using a polymer with distensibility similar to the human vena cava. METHODS: Fragments of the inferior vena cava were collected from 13 deceased kidney donors (aged 15-37 years) and were tested for deformation (strain) when subjected to distension at 50 N/cm2. Strips of 5 different polymers-thermic polyurethane and Agilus30 with Vero Magenta (AV) (in 3 different hardnesses) and silicone-were subjected to the same biomechanical tests and compared with the vena cava. A model of the caval bifurcation was produced with 3-D printing. RESULTS: The deformation (strain) of the vena cava wall was 0.16 ± 0.9 when submitted to stress close to 50 N/cm2. Silicone showed a strain higher than the standard deviation of venous fragments. The strain of AV resin 95 Shore was lower than the standard deviation of the venous fragments. AV Resins 70 and 85 Shore showed strains within the standard deviation of the venous specimen, with 70 Shore being closest to the mean venous strain. Therefore, this material was selected for modeling the caval bifurcation. The computed tomography scan image generated a computer model of the caval bifurcation and was printed in 3 dimensions. In addition, the segments of 2 adjacent vertebrae were also printed to reference the compression site. CONCLUSIONS: The 3-D printing of large veins can produce models with anatomy and biomechanics similar to those of human veins and opens a field of investigation into the hemodynamics of venous compression syndromes. Polymers with Shore A70 appear to have biomechanical properties similar to those of the vena cava wall. The model obtained in this study can be used in several in vitro studies of May-Thurner Syndrome.

Plasma advanced glycation end products and soluble receptor for advanced glycation end products as indicators of sterol content in human carotid atherosclerotic plaques.

Advanced glycation end products (AGEs) are independently related to cardiovascular disease (CVD) and favor cholesterol and oxysterol accumulation in macrophage foam cells. Soluble RAGE (sRAGE) impairs cellular AGE signaling alleviating the deleterious effects of AGE in atherogenesis. The association between plasma AGEs and sRAGE with the content of cholesterol, markers of cholesterol synthesis and absorption, and oxysterols in atherosclerotic plaques was evaluated in subjects undergoing carotid endarterectomy.Plasma and carotid plaques were obtained from symptomatic (n = 23) and asymptomatic subjects (n = 40). Lipids from plaques were extracted and sterols (oxysterols, cholesterol, desmosterol, lathosterol, sitosterol, and campesterol) were determined by using gas chromatography/mass spectrometry. Plasma total AGEs and pentosidine were measured by using fluorimetry and sRAGE by using ELISA.In symptomatic subjects´ atherosclerotic plaques, an increased amount of cholesterol (3x) and oxysterols [7 α-hydroxycholesterol (1.4x); 7 ß-hydroxycholesterol (1.2x); 25-hydroxycholesterol (1.3x); 24-hydroxycholesterol (2.7x), and 27-hydroxycholesterol, (1.15x)], with exception to 7 ketocholesterol, were found in comparison to asymptomatic individuals. Plasma total AGEs and pentosidine significantly and positively correlated to sterols accumulated in the atherosclerotic lesion, including cholesterol, desmosterol, campesterol, sitosterol, and oxysterols. On the other hand, sRAGE inversely correlated to total AGEs and pentosidine in plasma, and with major species of oxysterols, cholesterol, and markers of cholesterol synthesis and absorption in the atherosclerotic lesion. In multiple regression analyses, it was observed a significant inverse correlation between sRAGE and 24-hydroxycholesterol and desmosterol, and a positive significant correlation between pentosidine and 24-hydroxycholesterol, 27-hydroxycholesterol, and campesterol.In conclusion, the plasma concentration of AGEs and sRAGE is a tool to predict the accumulation of sterols in atherosclerotic lesions in symptomatic and asymptomatic individuals, helping to prevent and improve the management of acute cardiovascular complications.

Percutaneous endovascular delivery of calcium chloride to the intact porcine carotid artery: A novel animal model of arterial calcification.

OBJECTIVE: The present study evaluated the effect of endovascular administration of calcium chloride to the carotid artery of swines, to create a model of arterial calcification. METHODS: Fifteen Large White pigs were used for the study. Via endovascular treatment, carotid arteries were exposed during 9 min to either calcium chloride (experimental artery) or saline (control artery) with the use of the TAPAS catheter. Intravascular ultrasound (IVUS) imaging was obtained at baseline, postprocedure and at 30 days. Optical coherence tomography (OCT) imaging was obtained in vitro after carotids were harvested. Longitudinally cut parallel arterial segments were placed in a system of delicate clamps and underwent uniaxial strain test. All arteries underwent histopathological examination. RESULTS: Calcium chloride treated segments showed extensive circumferential parietal calcification evident on both IVUS and OCT. Reduction in minimal lumen area on IVUS was evident in experimental arteries both at 24 hr and 30 days postprocedure. Histopathologic assessment (Von Kossa stain) confirmed medial calcification with mild intimal thickening. Biomechanical testing showed treated segments to have smaller breaking strength and less elastic deformation than controls. CONCLUSION: We developed a nonexpensive, reproducible model of early carotid medial calcification in pigs. Our model has the potential to help the development of research to unravel mechanisms underlying arterial calcification, the use of current or new devices to treat calcified lesions as well as to serve as an option for training interventionalists on the use of such devices.

Characterization and Natural History of Patients with Internal Carotid Occlusion: A Comparative Study.

BACKGROUND: To characterize patients with internal carotid occlusion (ICO) with respect to demographic data, associated diseases, medical management, and risk factors and to compare these patients with those with nonsignificant stenosis (NSS; less than 50% stenosis). Secondary end points were new neurologic events, progression of contralateral degree of stenosis, cardiovascular symptoms, and death during follow-up. METHODS: Retrospective analysis was performed using data collected from clinical records and added to a prospective database. Missing data were obtained during phone interviews or requested medical appointments. RESULTS: From 2005 to 2013, 213 patients with ICO and 172 with NSS were studied (medium follow-up 37.81 months). Among the patients with ICO, a greater proportion were men, had a history of smoking, and presented with peripheral arterial disease and a lower creatinine clearance compared with those with NSS (P < 0.05). At the time of diagnosis, 76.1% of the patients with ICO were symptomatic compared with 35.5% of those with NSS (P = 0.000001). The patients in the ICO group exhibited significant progression of contralateral stenosis compared with those in the control group with progression on any side (15.0% vs. 2.3%, P = 0.00011). In addition, 18 patients in the ICO group (8.5%) exhibited new neurological symptoms compared with 13 (7.6%) in the NSS group (P = 0.41). When the ICO and NSS groups were combined, 10.8% of the initially symptomatic patients presented with new symptoms compared with 4.3% of those who were initially asymptomatic (P = 0.0218). The number of deaths was significantly higher among the patients in the ICO group (14.1% vs. 6.4%, P = 0.0150). CONCLUSIONS: Patients presenting with ICO have more risk factors and higher mortality by any cause. Initially, symptomatic patients will likely present with more neurological symptoms during follow-up, independent of carotid morphology, ICO, or NSS. Efforts must be made to identify those at risk before occlusion and to prevent secondary events and death.

Does elevated wall tension cause aortic aneurysm rupture? Investigation using a subject-specific heterogeneous model.

OBJECTIVE: To investigate whether peak wall tension in abdominal aortic aneurysm occurs at the site of rupture to test for a causative relationship. METHODS: Four ruptured and nine unruptured AAA were harvested whole from cadavers, followed by regional measurements of wall thickness, elastic parameters and failure tension. Finite element models were developed with subject-specific load-free AAA morphology and heterogeneous properties interpolated using a geodesic distance weighted approach from the measurements. The wall tension under uniform pressure and tension to failure tension ratio as an index of susceptibility to rupture were computed. As a secondary aim, the peak wall tension using this heterogeneous model approach was compared to the traditional homogeneous model approach in order to evaluate the reliability of the latter. RESULTS: The average peak wall tension in the ruptured group was 43% higher than in the unruptured group without statistical significance even though it was 54% larger in diameter. The site of peak wall tension was in the vicinity of the site of rupture in two ruptured AAA. The peak tension did not breach failure tension at the rupture site in any of the AAA. The traditional population-wide homogeneous model approach overestimated peak wall tension by just 3% compared to the subject-specific heterogeneous model approach. CONCLUSION: We failed to find adequate evidence of a causative relationship between peak wall tension and AAA rupture. The findings are not conclusive owing to study limitations such as ignoring intraluminal thrombus, sparse distribution of specimens procured and small study population.

Developing a new endograft for the treatment of juxtarenal aortic aneurysms: definition and experimentation.

OBJECTIVES: To analyze angiotomographic parameters of juxtarenal aneurysms to assess the applicability of an endograft model to patients and to create in vitro and in vivo models to assess the new endograft. METHODS: A total of 49 patients with juxtarenal aneurysms were submitted to angiotomographic evaluation, and parameters such as the aortic diameter, the length of the neck, and the angulations of the celiac trunk, superior mesenteric artery and renal arteries; the distances between them; and anatomic variations were analyzed. Based on these parameters, an endograft model was developed and tested in a newly created in vitro model of juxtarenal aneurysm. An experimental model of juxtarenal aneurysm was then established in six pigs weighing 50-60 kg to assess the new endograft model. RESULTS: The angiotomographic parameters of juxtarenal aneurysm measured in this study were similar to those reported in the literature and allowed the development of an endograft based on the hourglass concept, which was applicable to 85.8% of the patients. The in vitro model of juxtarenal aneurysm evidenced good radiopacity and functionality and permitted adjustments in the new device and technical improvements in the procedures for treating these aneurysms. In addition, the porcine model of juxtarenal aneurysm was successfully created in all six animals using a bovine pericardial patch, and use of the new endograft in three pilot procedures evidenced its feasibility. CONCLUSIONS: The Hourglass endograft was rendered applicable to treatment of the majority of patients with juxtarenal aneurysms simply by changing its diameter. Moreover, the new in vitro and in vivo models were shown to be effective for assessing both the presented endograft and experiments assessing the endovascular treatment of juxtarenal aneurysms.

Developing a new endograft for the treatment of juxtarenal aortic aneurysms: definition and experimentation

OBJECTIVES: To analyze angiotomographic parameters of juxtarenal aneurysms to assess the applicability of an endograft model to patients and to create in vitro and in vivo models to assess the new endograft. METHODS: A total of 49 patients with juxtarenal aneurysms were submitted to angiotomographic evaluation, and parameters such as the aortic diameter, the length of the neck, and the angulations of the celiac trunk, superior mesenteric artery and renal arteries; the distances between them; and anatomic variations were analyzed. Based on these parameters, an endograft model was developed and tested in a newly created in vitro model of juxtarenal aneurysm. An experimental model of juxtarenal aneurysm was then established in six pigs weighing 50-60 kg to assess the new endograft model. RESULTS: The angiotomographic parameters of juxtarenal aneurysm measured in this study were similar to those reported in the literature and allowed the development of an endograft based on the hourglass concept, which was applicable to 85.8% of the patients. The in vitro model of juxtarenal aneurysm evidenced good radiopacity and functionality and permitted adjustments in the new device and technical improvements in the procedures for treating these aneurysms. In addition, the porcine model of juxtarenal aneurysm was successfully created in all six animals using a bovine pericardial patch, and use of the new endograft in three pilot procedures evidenced its feasibility. CONCLUSIONS: The Hourglass endograft was rendered applicable to treatment of the majority of patients with juxtarenal aneurysms simply by changing its diameter. Moreover, the new in vitro and in vivo models were shown to be effective for assessing both the presented endograft and experiments assessing the endovascular treatment of juxtarenal aneurysms. .

The similarities and differences among patients with abdominal aortic aneurysms referred to a tertiary hospital and found at necropsy.

OBJECTIVE: To analyze the characteristics of patients with abdominal aortic aneurysms referred to a tertiary center and to compare with individuals with abdominal aortic aneurysm found at necropsy. METHODS: We have retrospectively analyzed the medical records of 556 patients with abdominal aortic aneurysm and 102 cases abdominal aortic aneurysm found at necropsy. RESULTS: At univariated analysis, hypertension, tobacco use and maximum diameter were significant risk factors for symptomatic aneurysm, while diabetes tended to be a protective factor for rupture. By logistic regression analysis, the largest transverse diameter was the only one significantly associated with abdominal aortic aneurysm rupture (p < .0001, odds ratio 1.7, 95% confidence interval 1.481-1.951). Intact abdominal aortic aneurysm found at necropsy showed similarities with outpatients in relation to abdominal aortic aneurysm diameter and risk factors. CONCLUSION: Intact abdominal aortic aneurysm at necropsy and at outpatients setting showed similarities that confirmed that abdominal aortic aneurysm repair is less offered to women, and they died more frequently with intact abdominal aortic aneurysm from other causes.

Relaçäo anatômica entre o nervo hipoglosso e a bifurcaçäo carotídea / Anatomical relation between the hypoglossal nerve and the carotid artery bifurcation

Introduçäo: Nas últimas décadas o índice de complicaçöes neurológicas centrais e mortalidade após cirurgia da artéria carótida (tumor do corpo carotídeo e endarterectomia) diminuiu significativamente. A lesäo de nervos cranianos continua pouco alterada e elevada, e a lesäo do nervo hipoglosso é a mais freqüente. Objetivo: Estudar a relaçäo entre o nervo hipoglosso e a bifurcaçäo carotídea, determinando a distância entre estas estruturas, além de estudar a influência do sexo, idade, raça e comprimento do pescoço sobre esta medida. Forma de estudo: Experimental. Material e método: Foram realizadas 38 dissecçöes da artéria carótida em 38 cadáveres. Os cadáveres eram colocados em posiçäo padräo (pescoço em extensäo de 95º). Após identificaçäo do nervo e da bifurcaçäo carotídea, foi medida a distância entre as estruturas. O comprimento do pescoço foi medido do processo mastóide até a incisura jugular. Resultados: O nervo hipoglosso näo foi encontrado abaixo da bifurcaçäo, e a distância entre o nervo e a bifurcaçäo variou de 0.5 a 4.3 cm (média = 2.1 cm, mediana = 2.0 cm, desvio padräo = 0.63 cm). Comprimento do pescoço, sexo, raça e idade näo demonstraram significância estatística. Conclusäo: Nesta amostra observamos grande variaçäo anatômica entre o nervo hipoglosso e a bifurcaçäo carotídea, e näo houve correlaçäo com comprimento do pescoço, sexo, raça e idade. Um melhor entendimento da anatomia do nervo hipoglosso e a sua variaçäo em relaçäo à bifurcaçäo carotídea säo importantes para prevenir lesäo do nervo hipoglosso

Autotransfusäo em cirurgia de aneurisma da aorta abdominal com processadora por fluxo descontínuo / Blood salvage in abdominal aortic resections with discontinuous flow processor

Os autores apresentam os resultados obtidos com métodos de autrotransfusäo pré-operatória, hemodiluiçäo e reaproveitamento de sangue intra-operatório para autotransfusäo em 7 pacientes submetidos `a correçäo cirúrgica de aneurisma de aorta abdominal. A coleta de sangue pré-operatória se deu em média 8 dias antes da cirurgia e o reaproveitamento de sangue intra-operatório foi realizado com filtros de Cardiotomia e processadoras automáticas de sangue por fluxo descontínuo. Cerca de 31% dos pacientes operados utilizaram exclusivamente seu próprio sangue e os resultados das metodologias empregadas foram semelhantes `as encontradas na literatura