The venous reflux.

Venous reflux is the most common cause of venous hemodynamic disorders. In this paper 2 issues are discussed: how and where does reflux arise and what are the hemodynamic consequences of retrograde flow. Pressure gradient and incompetent vein connecting both poles of the gradient are the prerequisite for venous reflux to arise. Ambulatory pressure gradient occurs during the activity of the calf muscle venous pump between deep veins of the thigh and the lower leg. Thus the incompetent reflux-carrying vein must connect the popliteal, femoral, profunda femoris, or iliac vein with 1 of the deep veins of the lower leg. Reflux can be considered as shunting of blood from thigh veins into the lower leg veins. The most frequently found incompetent veins are the long and short saphenous veins and perforators communicating with deep veins of the thigh. On the other hand, calf perforators emptying into the deep veins of the lower leg, where the lower pole of the pressure gradient is located, cannot be the feeding source of reflux. A physiological bidirectional flow takes place in calf perforators connecting superficial and deep veins of the lower leg and making them conjoined vessels. Venous reflux produces ambulatory venous hypertension. The quantity of reflux volume and not the localization of retrograde flow in superficial or deep veins is the most important hemodynamic factor. Reflux in superficial veins, when large enough, can cause the most serious symptoms of chronic venous insufficiency including leg ulcers. Plethysmographic findings have shown that incompetence of the femoral and calf perforating veins is hemodynamically unimportant. Large incompetent calf perforators are not the cause of venous abnormality but are the consequence of saphenous retrograde flow.