Vein Health Dictionary

VEINS that have become stretched and dilated. (See VEINS, DISEASES OF.)... varicose veins

The prominent vein which runs from near the bend of the elbow upwards along the inner side of the upper arm.... basilic vein

The vein which carries to the LIVER, blood that has been circulating in many of the abdominal organs. It is peculiar among the veins of the body in that it ends by breaking up into a capillary network instead of carrying the blood directly to the heart – a peculiarity which it shares only with certain small vessels in the kidneys. The PORTAL SYSTEM begins below in the haemorrhoidal plexus of veins around the lower end of the rectum; from this point, along the whole length of the intestines, the blood is collected into an inferior mesenteric vein upon the left, and a superior mesenteric vein upon the right side. The inferior mesenteric vein empties into the splenic vein, and the latter, uniting with the superior mesenteric vein immediately above the pancreas, forms the portal vein. The portal vein is joined by veins from the stomach and gallbladder, and ?nally divides into two branches which sink into the right and left lobes of the liver. (For their further course, see LIVER).

The organs from which the portal vein collects the blood are the large and small intestines, the stomach, spleen, pancreas, and gall-bladder.... portal vein

See thrombosis, deep vein.... deep vein thrombosis

One of 3 veins on each side of the neck that return deoxygenated blood from the head to the heart. The internal jugular, the largest of the 3 (internal, external, and anterior), arises at the base of the skull, travels down the neck alongside the carotid arteries, and passes behind the clavicle, where it joins the subclavian vein (the large vein that drains blood from the arms).... jugular vein

Blockage of a vein carrying blood away from the retina.

It usually results from thrombosis in the affected vein, and is more common in people who have glaucoma.

Retinal vein occlusion may cause visual disturbances, glaucoma, or blindness.... retinal vein occlusion

A major vein that runs the length of the leg just under the skin.

It is sometimes removed and used to bypass a blockage in blood vessels of the heart (see coronary artery bypass).... saphenous vein

When coronary arteries, narrowed by disease, cannot supply the heart muscle with su?cient blood, the cardiac circulation may be improved by grafting a section of vein from the leg to bypass the obstruction. Around 10,000 people in the United Kingdom have this operation annually and the results are usually good. It is a major procedure that lasts several hours and requires the heart to be stopped temporarily, with blood circulation and oxygenation taken over by a HEART-LUNG MACHINE.... coronary artery vein bypass grafting (cavbg)

See THROMBOSIS; VEINS, DISEASES OF.... deep vein thrombosis (dvt)

The vessels which return the blood to the heart after it has circulated through the tissues; they are both more numerous and more capacious than the ARTERIES.

Structure While of similar structure to an artery, veins have much thinner walls, with much less muscular tissue. Furthermore, most veins have one-way VALVES to ensure that the blood ?ows in the right direction. These are most numerous in the legs, then the arms, with few in the internal organs.

Chief veins Four pulmonary veins open into the left atrium of the heart, two from each lung. The superior vena cava returns the blood from the head, neck, and arms; while the inferior vena cava returns blood from the legs and abdomen. The large basilic vein that runs up the inner side of the upper arm is the vein usually opened in blood-letting (see VENESECTION). The great saphenous vein is of special interest, because of its liability to become distended or varicose. Within the abdomen, the inferior vena cava receives branches corresponding to several branches of the aorta, its largest branches being the hepatic veins, which return not only the blood that has reached the liver in the hepatic arteries, but also blood which comes from the digestive organs in the PORTAL VEIN to undergo a second capillary circulation in the liver.

There are several connections between the superior and inferior cava, the most important being three azygos veins that lie upon the sides of the spinal column, the veins on the front of the abdomen, and some veins that emerge from the abdomen at the navel and connect the portal system with those of the inferior and superior vena cava. (See also CIRCULATORY SYSTEM OF THE BLOOD.)... veins

See telangiectasia.... broken veins

Common disorders affecting veins include varicose veins, deep vein thrombosis (see thrombosis, deep vein), and thrombophlebitis.... veins, disorders of

an unpaired vein that arises from the inferior vena cava and drains into the superior vena cava, returning blood from the thorax and abdominal cavities.

b... azygos vein

two pairs of veins in the embryo that carry blood from the head (anterior cardinal veins) and trunk (posterior cardinal veins); they unite to form the common cardinal vein, which drains into the sinus venosus of the heart.... cardinal veins

a group of veins within the skull that drain blood from the venous sinuses of the dura mater to veins outside the skull.... emissary veins

one of several short veins originating within the lobes of the liver as small branches, which unite to form the hepatic veins. These lead directly to the inferior vena cava, draining blood from the liver.... hepatic vein

Veins are the blood vessels that convey blood back from the tissues towards the heart. Two common conditions that affect them are THROMBOSIS and varicosities (see below).

Varicose veins are dilated tortuous veins occurring in about 15 per cent of adults – women more than men. They most commonly occur in the legs but may also occur in the anal canal (HAEMORRHOIDS) and in the oesophagus (due to liver disease).

Normally blood ?ows from the subcutaneous tissues to the super?cial veins which drain via perforating veins into the deep veins of the leg. This ?ow, back towards the heart, is aided by valves within the veins. When these valves fail, increased pressure is exerted on the blood vessels leading to dilatations known as varicose veins.

Treatment is needed to prevent complications such as ulceration and bleeding, or for

cosmetic purposes. Treatment alternatives include injection with sclerosing agents to obliterate the lumen of the veins (sclerotherapy), or surgery; in the elderly or un?t, an elastic stocking may su?ce. One operation is the Trendelenburg operation in which the saphenous vein is disconnected from the femoral vein and individual varicose veins are avulsed. (See also VASCULITIS.)

Thrombosis Thrombosis occurs when blood, which is normally a liquid, clots within the vein to form a semisolid thrombus (clot). This occurs through a combination of reduced blood ?ow and hypercoagulability (a reduced threshold for clotting). The most common site for this to occur is in the deep veins of the leg, where it is known as a deep-vein thrombosis (DVT).

Predisposing factors include immobility (leading to reduced blood ?ow), such as during long journeys (e.g. plane ?ights) where there is little opportunity to stretch one’s legs; surgery (leading to temporary post-operative immobility and hypercoagulability of blood); oestrogen administration (low-dose oestrogen oral contraceptives carry a very low relative risk); and several medical illnesses such as heart failure, stroke and malignancy.

Deep-vein thrombosis presents as a tender, warm, red swelling of the calf. Diagnosis may be con?rmed by venogram (an X-ray taken following injection of contrast medium into the foot veins) or by ultrasound scanning looking for ?ow within the veins.

Prevention is important. This is why patients are mobilised and/or given leg exercises very soon after an operation, even major surgery. People should avoid sitting for long periods, particularly if the edge of the seat is hard, thus impeding venous return from the legs. Car drivers should stop regularly on a long journey and walk around; airline travellers should, where possible, walk round the aisle(s) and also exercise and massage their leg muscles, as well as drinking ample non-alcoholic ?uids.

Diagnosis and treatment are important because there is a risk that the clotted blood within the vein becomes dislodged and travels up the venous system to become lodged in the pulmonary arteries. This is known as PULMONARY EMBOLISM.

Treatment is directed at thinning the blood with ANTICOAGULANTS, initially with heparin and subsequently with WARFARIN for a period of time while the clot resolves.

Blocked super?cial veins are described as super?cial thrombophlebitis, which produces in?ammation over the vein. It responds to antiin?ammatory analgesics. Occasionally heparin and ANTIBIOTICS are required to treat associated thrombosis and infection.... veins, diseases of

The formation of a thrombus within deep-lying veins in the leg. The cause is usually a combination of slow blood flow through 1 part of the body (such as when sitting for long periods or when the tissues are compressed, as occurs in long-haul aircraft flights) and an increase in the clotting tendency of the blood, which occurs with dehydration, after surgery or injury, during pregnancy, and in women taking oral contraceptives. Deep vein thrombosis may also be caused by polycythaemia. Deep vein thrombosis is common in people with heart failure and those who have had a stroke or who have been immobile for long periods. Clots in the leg veins may cause pain, tenderness, swelling, discoloration, and ulceration of the skin, but they can be symptomless. A deep vein thrombosis is not necessarily serious in itself, but part of the clot may break off and travel in the bloodstream to the lungs. This is known as a pulmonary embolism.

A diagnosis is made by doppler ultrasound scanning.

Treatment depends on the site and extent of the clots.

Small clots may not need treatment if they are confined to the calf and the patient is mobile.

Otherwise, anticoagulant drugs or thrombolytic drugs are given.

If there is a high risk of a pulmonary embolism, thrombectomy may be performed.... thrombosis, deep vein

the veins draining most of the blood from the lower limbs and pelvic region. The right and left common iliac veins unite to form the inferior vena cava. They are each formed by the union of the internal and external iliac veins.... iliac veins

(brachiocephalic vein) either of two veins, one on each side of the neck, formed by the junction of the external jugular and subclavian veins. The two veins join to form the superior vena cava.... innominate vein

a vein carrying oxygenated blood from the lung to the left atrium. See pulmonary circulation.... pulmonary vein