Study of the Biomechanical and Histological Properties of the Abdominal Aorta of Diabetic Rats Exposed to Cigarette Smoke.

INTRODUCTION: In spite of the great relevance of abdominal aortic aneurysm, its etiopathogenesis is not fully understood. The biomechanical and histological study of the aortic wall may contribute to this elucidation. METHODS: Seventy-five male Wistar rats were divided into 4 groups: control (CG), smoker (SG), diabetic (DG), and diabetic + smoker (DSG). The SG and DSG rats were exposed to cigarette smoke for 30 min/day, 5 days a week. Diabetes was induced by the intravenous injection of streptozotocin. After 16 weeks, the abdominal aorta was collected for biomechanical, histological, and matrix metalloproteinase 2 (MMP-2) activity analyses. RESULTS: The valid biomechanical tests of 52 specimens were analyzed: 11 in the CG, 10 in the DG, 16 in the SG, and 15 in the DSG. The biomechanical analysis of the fragments showed no differences between the control, DG, SG, and DSG. Collagen deposition also did not present a significant difference between the studied groups. The total count of elastic fibers was higher in diabetic rats (DG and DSG) than in the SG. The inflammatory response observed in all experimental groups was significantly more intense than in the CG. Compared to the DSG, MMP-2 activity showed a significant decrease in the DG. CONCLUSIONS: Resistance and elasticity did not present a difference between the CG and the DG, SG, and DSG. Compared to the CG, the total count of elastic fibers, fragmentation of the elastic lamina, pericellular matrix deposition, and cell loss/substitution in the tunica media showed significant alterations in the aortic walls of the DG, SG, and DSG. MMP-2 activity was lower in the DG aorta than in the DSG aorta.

Development of a Puncture Technique for Implanting Temporary Vascular Shunts in a Porcine Model.

BACKGROUND: Temporary vascular shunts (TVSs) are an effective tool for rapidly restoring blood flow to a limb or organ that has experienced vascular injury and ischemia and for which revascularization is not an immediate option. Usually, through an opening in the skin, the TVS is positioned within the proximal and distal stumps of the injured vessel, restoring perfusion and stopping the ischemia. The aim of this study is to compare standard TVS technique and a developed puncture technique for implanting TVS and to evaluate the utility and feasibility of this protocol after arterial lesions, in pigs. METHODS: Vascular injuries were inflicted in both hind limbs of 30 pigs, and vascular interventions were performed, using standard and puncture TVS. Because each pig was implanted with both types of TVSs, it was possible to simultaneously monitor, analyze, and compare parameters such as, the mean arterial pressure (MAP, in mm Hg), blood flow (mL/min), and insertion times, in the same animal. RESULTS: It was observed that the MAP in the limbs recovered and approached systemic MAP, in 100% of the experiments, in both groups. Analysis of the blood flow data showed that this parameter was significantly reduced in the puncture TVS group (110.36 ± 9.99 mL/min vs. 153.20 ± 18.57 mL/min, P = 0.001). On the other hand, the insertion time for the standard TVS was significantly greater than that of the puncture shunt (15.32 ± 3.08 min vs. 10.37 ± 1.7 min, P = 0.001). Furthermore, it was found that the primary and secondary patency and complication rates were similar for both TVS types. CONCLUSION: Thus, given the adequate MAP recovery and reduction in implantation time observed in this experimental and in an animal model study, the use of the puncture TVS technique is effective and feasible.

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.

Treatment of varicose ulcer of the lower limbs by surgery and Unna boot: savings for the Brazilian healthcare system.

OBJECTIVE: To perform an analysis of the costs of treatment of varicose ulcers by radical surgery of varices and the use of Unna boot. METHODS: Fifteen outpatients were selected to receive treatment of varicose ulcers with radical surgery and Unna boot. The total cost of treatment was calculated (hospitalization, surgery, dressings, and outpatient's follow-up visits) and compared to the cost of clinical follow-up with daily simple dressing changes. RESULTS: The proposed treatment was on average 55.71% more economical than the management with daily dressings (approximately US$452.32 versus US$1,021.39). CONCLUSION: Radical varicose vein surgery associated with the use of the Unna boot proved meaningly less expensive for the public health system than clinical follow-up with daily dressings.

Tratamento da úlcera varicosa dos membros inferiores mediante cirurgia e bota de Unna: uma economia para o sistema de saúde brasileiro / Treatment of varicose ulcer of the lower limbs by surgery and Unna boot: savings for the Brazilian healthcare system

Objective: To perform an analysis of the costs of treatment of varicose ulcers by radical surgery of varices and the use of Unna boot. Methods: Fifteen outpatients were selected to receive treatment of varicose ulcers with radical surgery and Unna boot. The total cost of treatment was calculated (hospitalization, surgery, dressings, and outpatient?s follow-up visits) and compared to the cost of clinical follow-up with daily simple dressing changes. Results: The proposed treatment was on average 55.71% more economical than the management with daily dressings (approximately US$452.32 versus US$1,021.39). Conclusion: Radical varicose vein surgery associated with the useof the Unna boot proved meaningly less expensive for the public health system than clinical follow-up with daily dressings.

Objetivo: Realizar uma análise de custo do tratamento da úlcera varicosa mediante cirurgia radical de varizes e uso de bota de Unna. Métodos: quinze pacientes foram selecionados ambulatorialmente para receber o tratamento da úlcera varicosa com cirurgia radical de varizes e bota de Unna, sendo o custo total do tratamento contabilizado (internação, cirurgia, curativos e retornos ambulatoriais) e comparado ao custo do acompanhamento clínico com curativos simples trocados diariamente. Resultados: O tratamento proposto foi em média 55,71% mais econômico que o manejo com curativos diários (R$ 717,84 x R$ 1.620,95 ou aproximadamente US$ 452.32 x US$ 1,021.39). Conclusão: O emprego da cirurgia radical de varizes associado ao uso de bota de Unna provou-se expressivamente menos dispendioso para a saúde pública do que o acompanhamento clínico com curativos diários.