Ngoài ra, phẫu thuật tĩnh mạch đã trở thành tối thiểu suy có thể cùng tồn tại với bệnh động mạch ngoại vi trong 10-15% bệnh nhân bị loét chân [63, 64]. Trong nhiều trường hợp, kích hoạt trực tiếp cho loét là một số chấn thương bên ngoài vật lý | Mechanisms of Formation of Specific Types 41 Vascular Disease Venous Ulcers Around 70 of leg ulcers are venous in origin 61-63 Fig- 4-5 - Older sources of data may present a higher percentage- However in modern medicine the prevalence of venous ulcers is declining- This is attributed to the higher standards of medical care currently practiced- The significance of compression therapy is well recognized nowadays the use of low-molecular-weight heparins prevents venous thromboem- Fig. a b. Venous ulcers- a. Brown pigmentation of stasis dermatitis around the ulcer- b. Lipodermatosclerotic leg varicosities are seen in the medial area of the foot bolism in high-risk situations- In addition vein surgery has become minimally invasive- Venous insufficiency may coexist with peripheral arterial disease in 10-15 of patients with leg ulcers 63 64 - In many cases the direct trigger for ulceration is some external physical injury 1 65 -Whereas in a healthy person mild injury does not cause significant damage in patients with venous insufficiency the skin runs a much higher risk of developing ulceration- Histologically microvessels in areas subjected to chronic venous hypertension become dilated and coiled i-e- they have a glomerular appearance in intravital capillaroscopy- In the advanced disease the number of functioning perfused capillaries is markedly reduced 66-69 - The severity of cutaneous microangiopathy has been found to correlate closely to the development of clinical cutaneous trophic changes 66 70 - Mechanisms of Formation. At present the exact mechanism leading to the histologic picture and tissue damage in venous insufficiency remains uncertain- Nevertheless in recent years we have acquired an increased understanding of certain physiological mechanisms involved in this process- In chronic venous insufficiency the venous pressure or venous hypertension in the deep venous system may be transmitted to the superficial system- Partsch 71 suggested .
