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Paper read at the American European Symposium, Montreux 1974
ANATOMY AND PATHOPHYSIOLOGY OF VARICOSE VEINS
W. G. FEGAN
Clinical Research Department, Sir Patrick Dun's Hospital, Dublin
"Varicose veins" have long been used as the words to cover a wide variety of diseases affecting the venous system. These words draw attention to the dilated, tortuous veins that frequently are not present in patients who are most disabled. Symptoms of venous insufficiency are due to failure of the venous pumps of the lower limb and patients with prominent varicose veins usually have good pumps. The venous pump in the leg has two purposes. Firstly, with each step a high pressure peak or systole develops. This pressure peak establishes a favourable pressure gradient which enables the blood in the leg veins to overcome gravity and to return to the heart. The second function of the pump is to achieve low pressure or diastole between each step. If pressure in the veins cannot be lowered sufficiently by the venous pump there is interference with tissue fluid clearance. The ability of the limbs to achieve this is of more importance than the ability to achieve high pressure to promote forward flow. If low pressure is not achieved, tissue perfusion is impaired. There is a poor nutrition and oxygenation of the muscle, subcutaneous tissue and skin, and an accumulation of catabolites that give rise to the signs and symptoms of the post phlebotic limb.
The sequelae of pump failure is the development of a tired, heavy limb with bursting pain, oedema, induration, pigmentation and ulceration. If the pump failure is severe, venous claudication develops also. This is differentiated from arterial claudication, by the fact that the pain does not go when the patient stops walking and has to sit down and elevate the leg.
It is most important to remember that patients with severe pump failure may have minimal varicose veins and that severe varicose veins do not necessarily indicate or lead to poor pump function. It is quite common to find good pumps in the presence of impressive varices and indeed good pumps may be needed for these to develop.
Many theories have been put forward concerning the aetiology of varicose veins. I feel that turbulent flow is of extreme importance in their development. It is accepted that post stenotic dilatation in the arterial system is an effect of turbulence. In rigid tubes turbulent flow may cause damage to the walls of the tube. In patients with varicosity of the long saphenous system retrograde flow is present and turbulence is usually present also. The turbulence is probably produced by the fact that the retrograde flow of blood is partially obstructed by the incompetent valves in the vein. This is supported by the fact that dilatation occurs beneath the valves.
Turbulence is related to velocity of flow. To achieve high velocity flow good muscle pumps are necessary. Blood is emptied from the lower superficial veins by good muscle pumps. Higher up the leg if incompetent perforating veins are present the blood flows through them into the superficial system and down these superficial veins producing turbulent retrograde flow. Asymmetrical pin point jetting of high velocity retrograde flow produces changes in the vein wall at the point the jet hits the wall. These changes are characterized by the wasting of the constituents of the media of the vein wall and thickening of the intima.
Damage to the valves in the perforating veins is more important than damage to the valves at the termination of the long and short saphenous. The retrograde filling of the venous pumps from the saphenous opening, if the valve is incompetent, is so spectacular that the retrograde flow through incompetent perforating veins is not so easily noticed.
If the valves associated with muscle pumps are intact and functioning well considerable retrograde flow at the saphenous opening can be compensated for adequately. This will ensure the maintenance of low pressure during walking in the lower veins of the leg.
However, if the valves are incompetent the pumps have a reduced capacity to return blood to the heart and on walking, blood at high pressure is pumped from the deep to the superficial system. It is essential therefore to examine patients with venous disease walking as well as standing.
Methods of treating patients with venous insufficiency should obviously therefore, be directed at repairing the damaged muscle pumps by closing the leaking perforating veins, rather than concentrating on the removal of the dilated superficial veins. Cosmetically these may be ugly but they are of little importance to the patients symptoms. In fact, their removal may leave the patients with symptoms and a disabled limb.