Pathophysiology of deep vein thrombosis.

Deep venous thrombosis is a frequent, multifactorial disease and a leading cause of morbidity and mortality. Most of the time deep venous thrombosis is triggered by the interaction between acquired risk factors, such as hip fracture, pregnancy, and immobility, and hereditary risk factors such as thrombophilias. The mechanisms underlying deep venous thrombosis are not fully elucidated; however, in recent years, important advances have shed light on the role of venous flow, endothelium, platelets, leukocytes, and the interaction between inflammation and hemostasis. It has been described that the alteration of venous blood flow produces endothelial activation, favoring the adhesion of platelets and leukocytes, which, through tissue factor expression and neutrophil extracellular traps formation, contribute to the activation of coagulation, trapping more cells, such as red blood cells. Thus, the concerted interaction of these phenomena allows the formation and growth of the thrombus. In this work, the main mechanisms involved in the pathophysiology of deep vein thrombosis will be described.

Distribution of saphenous vein valves and its pratical importance / Distribuição das válvulas da veia safena magna e sua importância prática

Objective: Among the veins used as a graft in myocardial revascularizations and ends, great saphenous vein is the most used. Knowing the presence and location of valves has great importance when evaluating the surgical anatomy of the great saphenous vein. Despite major surgical application and many works involving great saphenous vein, the number of valves present in it from the saphenous hiatus to the medial epicondyle of the femur is still described inaccurately. The objective of this study is to quantify the valves of the great saphenous vein from the saphenous hiatus to the medial epicondyle of the femur to determine the best portion of the great saphenous vein to perform revascularization surgeries. Methods: This is a crosssectional observational study in which it was analyzed great saphenous vein extracted from 30 cadavers. It was measured the length of the veins; (diameter) at its proximal, middle and distal, quantifying the number of valves in each one and the total number of valves at the great saphenous vein. Results: The frequency of valves in the great saphenous vein taken from the medial epicondyle of the femur to the saphenous hiatus was 4.82, ranging between 2 and 9. Moreover, there is a significant difference in the number of valves in the proximal and distal relative to the average. Conclusion: the median and distal portions of the saphenous vein in the thigh, are the best options for the realization of bridges due to the fact that these portions have fewer valves which therefore would tend to decrease the risk of complications connected with the valves in these grafts. .

Objetivo: Dentre as veias empregadas para revascularizações do miocárdio e de extremidades, a veia safena magna é a mais utilizada. Conhecer a presença e localização de válvulas é de grande importância quando se avalia a anatomia cirúrgica da veia safena magna. Apesar de grande aplicação cirúrgica e de muitos trabalhos envolvendo a veia safena magna, o número de válvulas presente nela desde o hiato safeno até o epicôndilo medial do fêmur ainda é descrito de forma imprecisa. O objetivo do presente trabalho é quantificar as válvulas da veia safena magna desde o hiato safeno até o epicôndilo medial do fêmur para determinar a melhor porção da veia safena magna para a realização de cirurgias de revascularização. Métodos: Este é um estudo transversal e observacional em que foram analisadas veias safena magna extraídas de 30 cadáveres. Foram realizadas as medidas das variáveis do comprimento das veias; (diâmetro) em suas porções proximal, média e distal; quantificação do número de válvulas nestas e número de válvulas total na veia safena magna. Resultados: A frequência de válvulas da veia safena contadas desde o epicôndilo medial do fêmur até o hiato safeno foi de 4,82, podendo variar entre 2 e 9. Além disso, houve diferença significante do número de válvulas da porção proximal em relação à média e distal. Conclusão: As porções média e distal da veia safena magna na coxa são as melhores opções para a realização de pontes em decorrência do fato destas porções terem menor quantidade de válvulas o que, portanto, tenderia a diminuir o risco de complicações relacionadas as válvulas nestes enxertos. .