Posterior Arch Vein

Posterior Arch Vein

FIGURE 4.2 This diagrammatic representation of the Great Saphenous Vein emphasizes it relationship to perforating veins and the Posterior Arch Vein. (Redrawn from Mozes G, Gloviczki P, Kadar A, Carmichael SW. Chapter 2, Anatomy of the Perforating Veins in Gloviczki, P, and Bergan, JJ, eds. Atlas of Endoscopic Perforating Vein Surgery. Springer, London. 1998.)

FIGURE 4.2 This diagrammatic representation of the Great Saphenous Vein emphasizes it relationship to perforating veins and the Posterior Arch Vein. (Redrawn from Mozes G, Gloviczki P, Kadar A, Carmichael SW. Chapter 2, Anatomy of the Perforating Veins in Gloviczki, P, and Bergan, JJ, eds. Atlas of Endoscopic Perforating Vein Surgery. Springer, London. 1998.)

Vortical Veins

FIGURE 4.3 Deep connections of the main thigh and leg perforating veins are shown in this diagram of the deep veins of the lower extremity. (Redrawn from Mozes G, Gloviczki P, Kadar A, Carmichael SW. Chapter 2, Anatomy of the Perforating Veins in Gloviczki, P, and Bergan, JJ, eds. Atlas of Endoscopic Perforating Vein Surgery. Springer, London. 1998.)

FIGURE 4.3 Deep connections of the main thigh and leg perforating veins are shown in this diagram of the deep veins of the lower extremity. (Redrawn from Mozes G, Gloviczki P, Kadar A, Carmichael SW. Chapter 2, Anatomy of the Perforating Veins in Gloviczki, P, and Bergan, JJ, eds. Atlas of Endoscopic Perforating Vein Surgery. Springer, London. 1998.)

are dramatic changes in venous pressure. The only point in which the pressure remains constant is the hydrostatic indifferent point just below the diaphragm. All pressures distal to this point are increased due to the weight of the blood column from the right atrium. When assuming the upright position, there is an accumulation of approximately 500 ml of blood in the lower extremities, largely due to reflux through the valveless vena cava and iliac veins. There is some loss of fluid into the tissues, and this is collected by the lymphatic system and returned to the venous system.

Venous valves play an important role in transporting blood from the lower extremities to the heart. In order for valve closure to occur, there must be a reversal of the normal transvalvular pressure gradient. A pressure and generated velocity flow exceeding 30 cm/second leads to valve closure. Direct observation of human venous valves has been made possible by specialized ultrasound techniques.7 Venous flow is not in a steady state but is normally pulsatile, and venous valves undergo regular opening and closing cycles. Even when fully opened, the cross-sectional area between the leaflets is 35% smaller than that of the vein distal to the valve. Flow through the valve separates into a proximally directed jet and vortical flow into the sinus pocket proximal to the valve cusp. The vortical flow prevents stasis and ensures that all surfaces of the valve are exposed to sheer stress. Valve closure develops when the vortical flow pressure exceeds the proximally directed jet flow.

The role of venous valves in an individual quietly standing is not well understood. Pressures in the superficial and deep veins are essentially the same during quiet standing, but as Arnoldi has found, the pressure in the deep veins is 1 mm higher, which would tend to keep the valves in the perforating veins closed.8 Normally functioning perforating vein valves protect the skin and subcutaneous tissues from the effects of muscular contraction pressure. This muscular contraction pressure may exceed 100 to 130 mmHg.

Intuitively, the role of venous valves during muscular exercise is obvious, since their major purpose is to promote antegrade flow from superficial to deep. Volume and pressure changes in veins within the calf occur with muscular activity. In the resting position, with the foot flat on the floor, there is no flow. However, in the heel strike position, the venous plexus under the heel and plantar surface of the foot (Bejar's plexus) is emptied proximally. Blood flows from the foot and ankle into the deep veins of the calf. Then, calf contraction transports this blood into the deep veins of the thigh, and henceforth, blood flow proceeds to the pelvic veins, vena cava, and ultimately to the heart all due to the influence of lower extremity muscular contraction.9

How To Deal With Rosacea and Eczema

How To Deal With Rosacea and Eczema

Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.

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