Veins are most commonly affected by thrombosis, or blood clots that develop within the vein, and insufficiency, which is the failure of the one-way valves present in veins which prevent the backward flow of blood within veins. In most vein practices, venous insufficiency is most common condition managed.
An understanding of venous disease and its treatment depends first upon an adequate understanding of venous anatomy and function. While venous anatomy has been known for years, there exists considerable variation from what might be considered the “normal” pattern. Knowledge of venous function, and particularly abnormal function, has grown considerably in recent years. The use of newer diagnostic tests, particularly ultrasound, has allowed physicians to better understand a given patient’s venous anatomy and function, and thereby tailor treatment for any venous disease present.
Anatomy & Venous System Review
Normal Venous Anatomy and Function
The venous system of the lower extremities is a complex of thin-walled and low-pressure vessels that return blood back to the heart after circulation to the tissues. This transport of blood is facilitated by several factors. Low central pressures in the chest cavity promote blood return to the heart. Active propulsion of blood by muscular contraction in the calves and thighs occurs during ambulation and functions as a “peripheral heart” driving blood return. Finally, the veins of the lower extremities usually contain venous valves that prevent the backward flow of blood.
The veins of the lower extremities can be conveniently divided into three types. The deep veins are those that are surrounded by muscular tissue and therefore can function as part of the “peripheral heart” noted above. The superficial veins include the greater and lesser saphenous veins, along with their major tributaries. The perforator veins penetrate the fascia that surrounds the muscle bundles and divert blood from the superficial to the deep venous system.
Deep Venous System
The deep veins include the gastrocnemius, peroneal and tibial veins in the calf, the popliteal veins behind the knee, and the femoral veins in the thigh. The deep veins are ultimately responsible for most of the venous drainage from the lower extremities. With the combination of active muscular contraction and normal venous valvular function, the deep veins provide the only active propulsion of venous return to the heart.
The greater saphenous vein ascends along the inner aspect of the calf and thigh and ultimately drains into the femoral vein at the groin, through the saphenofemoral junction. Major tributaries (branches) include the posterior arch vein in the calf, the posteromedial vein and anterolateral vein in the thigh and the inferior epigastric vein in the groin.
The lesser saphenous vein lies on the posterior aspect of the calf and drains into the popliteal venous system behind the knee, through the saphenopopliteal junction. Not infrequently, the lesser saphenous vein drains into other venous channels, including the vein of Giacomini, which in turn drains into the greater saphenous vein.
There are a number of perforating veins that communicate between the superficial and deep venous systems. It is important to keep two thoughts in mind when discussing the perforating veins; that they are quite variable in their location and prevalence, and that they are normal venous structures even in the absence of venous disease.
The function of perforating veins is to direct blood flow from the superficial venous system to the deep venous system. The perforating venous system can sometimes be the origin of venous disease but can also frequently be only indirectly affected by disease in the other systems. Classically defined perforating veins include the Hunterian and Dodd perforators in the thigh, the Boyd and Cockett perforators in the calf, and a number of perforators in the foot.