Thrombus Health Dictionary

The formation of a thrombus (BLOOD CLOT) in one part of the circulatory system from which a portion becomes detached and lodges in another blood vessel, partially or completely obstructing the blood ?ow (an EMBOLISM). Most commonly a thrombus is formed in the veins of the leg – DEEP VEIN THROMBOSIS (DVT)

– and the embolism lodges in the pulmonary (lung) circulation. PULMONARY EMBOLISM is a potentially fatal condition and requires urgent anticoagulant treatment (see ANTICOAGULANTS) and sometimes surgery. Extended periods lying in bed or prolonged sitting in a con?ned position such as a car or aeroplane can cause DVT; venous thromboses in the legs may occur after surgery and preventive anticoagulant treatment with HEPARIN and warfarin is often used. Similar treatment is needed if a thrombus develops. STREPTOKINASE is also used to treat thromboembolism.... thromboembolism

The formation of a thrombus (blood clot) in an undamaged blood vessel. A thrombus that forms within an artery supplying the heart muscle (coronary thrombosis) is the usual cause of myocardial infarction. A thrombus in an artery of the brain (cerebral thrombosis) is a common cause of stroke. Thrombi sometimes form in veins, either just below the skin or in deeper veins (see thrombosis, deep vein).In arteries, thrombus formation may be encouraged by atherosclerosis, smoking, hypertension, and damage to blood vessel walls from arteritis and phlebitis.

An increased clotting tendency may occur in pregnancy, when using oral contraceptives, or through prolonged immobility.

An arterial thrombosis may cause no symptoms until blood flow is impaired.

Then, there is reduced tissue or organ function and sometimes severe pain.

Venous thrombosis may also cause pain and swelling.

Diagnosis is made by doppler ultrasound.

In some cases, angiography or venography may also be used.

Treatment may include anticoagulant drugs or thrombolytic drugs, nonsteroidal anti-inflammatory drugs, and antibiotic drugs.

In life-threatening cases, thrombectomy may be needed.... thrombosis

Narrowing or blockage of one of the coronary arteries by a thrombus (blood clot), depriving a section of the heart muscle of vital oxygen. In most cases, the thrombus forms in a blood vessel already narrowed by atherosclerosis. Sudden blockage of a coronary artery causes an acute myocardial infarction (heart attack).... coronary thrombosis

The removal of a thrombus that is blocking a blood vessel. It is performed as an emergency procedure if a major artery is blocked, or as a precautionary measure if there is a risk of an embolus breaking off. Before surgery, the site of the thrombus is established by angiography and the patient may be given anticoagulant drugs.... thrombectomy

These consist either of expanding masses (lumps or tumours), or of areas of shrinkage (atrophy) due to degeneration, or to loss of blood supply, usually from blockage of an artery.

Tumours All masses cause varying combinations of headache and vomiting – symptoms of raised pressure within the inexpansible bony box formed by the skull; general or localised epileptic ?ts; weakness of limbs or disordered speech; and varied mental changes. Tumours may be primary, arising in the brain, or secondary deposits from tumours arising in the lung, breast or other organs. Some brain tumours are benign and curable by surgery: examples include meningiomas and pituitary tumours. The symptoms depend on the size and situation of the mass. Abscesses or blood clots (see HAEMATOMA) on the surface or within the brain may resemble tumours; some are removable. Gliomas ( see GLIOMA) are primary malignant tumours arising in the glial tissue (see GLIA) which despite surgery, chemotherapy and radiotherapy usually have a bad prognosis, though some astrocytomas and oligodendronogliomas are of low-grade malignancy. A promising line of research in the US (in the animal-testing stage in 2000) suggests that the ability of stem cells from normal brain tissue to ‘home in’ on gliomal cells can be turned to advantage. The stem cells were chemically manipulated to carry a poisonous compound (5-?uorouracil) to the gliomal cells and kill them, without damaging normal cells. Around 80 per cent of the cancerous cells in the experiments were destroyed in this way.

Clinical examination and brain scanning (CT, or COMPUTED TOMOGRAPHY; magnetic resonance imaging (MRI) and functional MRI) are safe, accurate methods of demonstrating the tumour, its size, position and treatability.

Strokes When a blood vessel, usually an artery, is blocked by a clot, thrombus or embolism, the local area of the brain fed by that artery is damaged (see STROKE). The resulting infarct (softening) causes a stroke. The cells die and a patch of brain tissue shrinks. The obstruction in the blood vessel may be in a small artery in the brain, or in a larger artery in the neck. Aspirin and other anti-clotting drugs reduce recurrent attacks, and a small number of people bene?t if a narrowed neck artery is cleaned out by an operation – endarterectomy. Similar symptoms develop abruptly if a blood vessel bursts, causing a cerebral haemorrhage. The symptoms of a stroke are sudden weakness or paralysis of the arm and leg of the opposite side to the damaged area of brain (HEMIPARESIS), and sometimes loss of half of the ?eld of vision to one side (HEMIANOPIA). The speech area is in the left side of the brain controlling language in right-handed people. In 60 per cent of lefthanders the speech area is on the left side, and in 40 per cent on the right side. If the speech area is damaged, diffculties both in understanding words, and in saying them, develops (see DYSPHASIA).

Degenerations (atrophy) For reasons often unknown, various groups of nerve cells degenerate prematurely. The illness resulting is determined by which groups of nerve cells are affected. If those in the deep basal ganglia are affected, a movement disorder occurs, such as Parkinson’s disease, hereditary Huntington’s chorea, or, in children with birth defects of the brain, athetosis and dystonias. Modern drugs, such as DOPAMINE drugs in PARKINSONISM, and other treatments can improve the symptoms and reduce the disabilities of some of these diseases.

Drugs and injury Alcohol in excess, the abuse of many sedative drugs and arti?cial brain stimulants – such as cocaine, LSD and heroin (see DEPENDENCE) – can damage the brain; the effects can be reversible in early cases. Severe head injury can cause localised or di?use brain damage (see HEAD INJURY).

Cerebral palsy Damage to the brain in children can occur in the uterus during pregnancy, or can result from rare hereditary and genetic diseases, or can occur during labour and delivery. Severe neurological illness in the early months of life can also cause this condition in which sti? spastic limbs, movement disorders and speech defects are common. Some of these children are learning-disabled.

Dementias In older people a di?use loss of cells, mainly at the front of the brain, causes ALZHEIMER’S DISEASE – the main feature being loss of memory, attention and reasoned judgement (dementia). This affects about 5 per cent of the over-80s, but is not simply due to ageing processes. Most patients require routine tests and brain scanning to indicate other, treatable causes of dementia.

Response to current treatments is poor, but promising lines of treatment are under development. Like Parkinsonism, Alzheimer’s disease progresses slowly over many years. It is uncommon for these diseases to run in families. Multiple strokes can cause dementia, as can some organic disorders such as cirrhosis of the liver.

Infections in the brain are uncommon. Viruses such as measles, mumps, herpes, human immunode?ciency virus and enteroviruses may cause ENCEPHALITIS – a di?use in?ammation (see also AIDS/HIV).

Bacteria or viruses may infect the membrane covering the brain, causing MENINGITIS. Viral meningitis is normally a mild, self-limiting infection lasting only a few days; however, bacterial meningitis – caused by meningococcal groups B and C, pneumococcus, and (now rarely) haemophilus – is a life-threatening condition. Antibiotics have allowed a cure or good control of symptoms in most cases of meningitis, but early diagnosis is essential. Severe headaches, fever, vomiting and increasing sleepiness are the principal symptoms which demand urgent advice from the doctor, and usually admission to hospital. Group B meningococcus is the commonest of the bacterial infections, but Group C causes more deaths. A vaccine against the latter has been developed and has reduced the incidence of cases by 75 per cent.

If infection spreads from an unusually serious sinusitis or from a chronically infected middle ear, or from a penetrating injury of the skull, an abscess may slowly develop. Brain abscesses cause insidious drowsiness, headaches, and at a late stage, weakness of the limbs or loss of speech; a high temperature is seldom present. Early diagnosis, con?rmed by brain scanning, is followed by antibiotics and surgery in hospital, but the outcome is good in only half of affected patients.

Cerebral oedema Swelling of the brain can occur after injury, due to engorgement of blood vessels or an increase in the volume of the extravascular brain tissue due to abnormal uptake of water by the damaged grey (neurons) matter and white (nerve ?bres) matter. This latter phenomenon is called cerebral oedema and can seriously affect the functioning of the brain. It is a particularly dangerous complication following injury because sometimes an unconscious person whose brain is damaged may seem to be recovering after a few hours, only to have a major relapse. This may be the result of a slow haemorrhage from damaged blood vessels raising intracranial pressure, or because of oedema of the brain tissue in the area surrounding the injury. Such a development is potentially lethal and requires urgent specialist treatment to alleviate the rising intracranial pressure: osmotic agents (see OSMOSIS) such as mannitol or frusemide are given intravenously to remove the excess water from the brain and to lower intracranial pressure, buying time for de?nitive investigation of the cranial damage.... brain, diseases of

A channel for venous blood placed either side of the sphenoid bone at the base of the SKULL behind the eye sockets. Blood drains into it from the eye, the nose, the brain and part of the cheek, and leaves via the internal jugular and facial veins. Sometimes the sinus becomes blocked by a blood clot (thrombus), usually a complication of a nearby bacterial infection. A potentially serious condition, it should be treated with thrombolysis and antibiotics.... cavernous sinus

An antiplatelet drug, best given under the supervision of a specialist. It inhibits the aggregation of PLATELETS in the blood that occurs in THROMBUS formation, and is used with HEPARIN and ASPIRIN to prevent early myocardial infarction (heart attack – see HEART, DISEASES OF) in patients with unstable ANGINA PECTORIS.... eptifibitide

A group of drugs, also known as thrombolytics, with the ability to break down the protein FIBRIN, the prime constituent of blood clots (see THROMBUS; THROMBOSIS). They are used to disperse blood clots that have formed in the vessels of the circulatory system. The group includes STREPTOKINASE, alteplase and reteplase. The drugs work by activating PLASMINOGEN to form PLASMIN which degrades ?brin and breaks up the blood clot (see COAGULATION).... fibrinolytic drugs

Bloodlessness of a part of the body, due to contraction, spasm, constriction or blocking (by EMBOLUS or by THROMBUS) of the arteries: for example, of the heart.... ischaemia

The term applied to a small stone formed in a vein (see VEINS) as a result of calci?cation of a THROMBUS.... phlebolith

Platelets are the small, rather uniform fragments of large bone marrow cells that aid the blood in coagulation, hemostasis, inflammation, and thrombus formation. Mild subclotting and sticking is a common early condition that can lead to thrombosis, atherosclerosis, and strokes, and can be helped by an aspirin a day, better fat digestion, and Ceanothus.... platelet aggregation

These are compounds with the property of breaking up blood clots in the circulatory system (see BLOOD CLOT; THROMBUS; THROMBOSIS; FIBRINOLYTIC DRUGS).... thrombolytic agents

A recently introduced antiplatelet drug, which decreases clumping of blood PLATELETS and thus inhibits the formation of clots (see BLOOD CLOT; THROMBUS). It is used to prevent episodes in patients with a history of symptomatic ischaemic disease such as STROKE and INTERMITTENT CLAUDICATION. The drug should be started under hospital supervision.... ticlopidine

A natural PROTEIN that occurs in the body. It has the property of breaking down a THROMBUS in a blood vessel (see THROMBOLYSIS). It is e?ective only in the presence of FIBRIN and activates plasminogen, which occurs normally on the surface of the ?brin. TPA is an important thrombolytic treatment immediately after a myocardial infarction (see HEART, DISEASES OF).... tissue plasminogen activator (tpa, tpa)

The formation of a thrombus (blood clot) in an artery in the brain. The clot may block the artery, cutting off the supply of blood, nutrients, and oxygen to a region of the brain, causing a stroke.... cerebral thrombosis

Reduced physical activity, for example, through disease, injury, or following major surgery. Immobility is particularly harmful in the elderly because it causes muscle wasting and progressive loss of function.

Total immobility can produce complications including bedsores, pneumonia, or contractures. A common complication of partial immobility is oedema (fluid retention), which causes swelling of the legs. Rarely, sluggish blood flow encourages formation of a thrombus (abnormal blood clot) in a leg vein. Regular physiotherapy and adequate nursing care are important for any person who is totally immobile.... immobility

a solid or semisolid mass formed as the result of *blood coagulation, either within the blood vessels and heart after death or elsewhere in the body during life (a mass of coagulated blood formed in the cardiovascular system during life is called a thrombus: see thrombosis). A blood clot consists of a meshwork of the protein *fibrin in which various blood cells are trapped.... blood clot

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

An imaging procedure that enables blood vessels to be seen clearly on X-ray film following the injection of a contrast medium (a substance

that is opaque to X-rays). Angiography is used to detect conditions that alter the appearance of blood vessels, such as aneurysm, and narrowing or blockage of blood vessels by atherosclerosis, or by a thrombus or embolus. It is also used to detect changes in the pattern of blood vessels that supply organs injured or affected by a tumour.

Carotid angiography (of the arteries in the neck) may be used to investigate transient ischaemic attacks. Cerebral angiography can be used to detect an aneurysm in the brain or pinpoint the position of a brain tumour. Coronary angiography, often combined with cardiac catheterization, can identify the sites of narrowing or blockage in coronary artery disease. Digital subtraction angiography uses computer techniques to process images and remove unwanted background information.

Angiographic techniques have been adapted to allow certain treatments that, in some cases, eliminate the need for surgery (see angioplasty, balloon; embolization). (See also aortography.)... angiography

Blockage of a venous sinus (a channel for venous blood deep in the skull behind an eye socket) by a thrombus (abnormal blood clot). The condition is usually a complication of a bacterial infection in an area drained by the veins entering the sinus. Such infections include cellulitis of the face, infections of the mouth, eye, or middle ear, sinusitis, and septicaemia.

Symptoms include severe headache, high fever, pain and loss of sensation in and above the affected eye, and proptosis (protrusion of the eyeball). Vision may become blurred and eye movements paralysed due to pressure on the optic nerve and other cranial nerves. Treatment with antibiotic drugs and anticoagulant drugs can save vision. Left untreated, blindness results, and the infection may prove fatal.... cavernous sinus thrombosis

an *ultrasound technique to look for deep vein *thrombosis. Pressing the vein with the ultrasound probe usually causes it to empty and flatten, which does not occur if there is thrombus in the lumen. See also venography.... compression venography

n. a surgical ‘re-bore’ of an artery that has become obstructed by *atheroma with or without a blood clot (thrombus); the former operation is known as thromboendarterectomy. The inner part of the wall is removed together with any clot that is present. This restores patency and arterial blood flow to the tissues beyond the obstruction. The technique is most often applied to obstruction of the carotid arteries (carotid endarterectomy) or of the arteries that supply the legs.... endarterectomy

n. the death of part or the whole of an organ that occurs when the artery carrying its blood supply is obstructed by a blood clot (thrombus) or an *embolus. For example, *myocardial infarction, affecting the muscle of the heart, follows coronary thrombosis. A small localized area of dead tissue produced as a result of an inadequate blood supply is known as an infarct. Infarcts also arise when venous outflow from an organ or tissue is obstructed, as occurs when the ovary or testis twist on their vascular pedicles (stalks), or when the sigmoid colon twists in *volvulus.... infarction

The cause of: coronary occlusion, coronary blockage, coronary thrombosis. A heart attack occurs when a coronary artery becomes blocked by swellings composed, among other things, of cholesterol. Such swellings may obstruct the flow of blood leading to a blood clot (thrombus). Cholesterol is a major cause of CHD.

Coronary thrombosis is more common in the West because of its preference for animal fats; whereas in the East fats usually take the form of vegetable oils – corn, sunflower seed, sesame, etc. Fatty deposits (atheroma) form in the wall of the coronary artery, obstructing blood-flow. Vessels narrowed by atheroma and by contact with calcium and other salts become hard and brittle (arterio-sclerosis) and are easily blocked. Robbed of oxygen and nutrients heart muscle dies and is replaced by inelastic fibrous (scar) tissue which robs the heart of its maximum performance.

Severe pain and collapse follow a blockage. Where only a small branch of the coronary arterial tree is affected recovery is possible. Cause of the pain is lack of oxygen (Vitamin E). Incidence is highest among women over 40 who smoke excessively and who take The Pill.

The first warning sign is breathlessness and anginal pain behind the breastbone which radiates to arms and neck. Sensation as if the chest is held in a vice. First-line agent to improve flow of blood – Cactus.

For cholesterol control target the liver. Coffee is a minor risk factor.

Measuring hair calcium levels is said to predict those at risk of coronary heart disease. Low hair concentrations may be linked with poor calcium metabolism, high aortic calcium build-up and the formation of plagues. (Dr Allan MacPherson, nutritionist, Scottish Agricultural College, Ayr, Scotland)

Evidence has been advanced that a diagonal ear lobe crease may be a predictor for coronary heart disease. (American Journal of Cardiology, Dec. 1992)

Tooth decay is linked to an increased risk of coronary heart disease and mortality, particularly in young men. (Dr Frank De Stefano, Marshfield Medical Research Foundation, Wisconsin, USA) Treatment. Urgency. Send for doctor or suitably qualified practitioner. Absolute bedrest for 3 weeks followed by 3 months convalescence. Thereafter: adapt lifestyle to slower tempo and avoid undue exertion. Stop smoking. Adequate exercise. Watch weight.

Cardiotonics: Motherwort, Hawthorn, Mistletoe, Rosemary. Ephedra, Lily of the Valley, Broom.

Cardiac vasodilators relax tension on the vessels by increasing capacity of the arteries to carry more blood. Others contain complex glycosides that stimulate or relax the heart at its work. Garlic is strongly recommended as a preventative of CHD.

Hawthorn, vasodilator and anti-hypertensive, is reputed to dissolve deposits in thickened and sclerotic arteries BHP (1983). It is believed to regulate the balance of lipids (body fats) one of which is cholesterol.

Serenity tea. Equal parts: Motherwort, Lemon Balm, Hawthorn leaves or flowers. 1 heaped teaspoon to each cup boiling water; infuse 5-15 minutes; 1 cup freely.

Decoction. Combine equal parts: Broom, Lily of the Valley, Hawthorn. 1-2 teaspoons to each cup water gently simmered 20 minutes. Half-1 cup freely.

Tablets/capsules. Hawthorn, Motherwort, Cactus, Mistletoe, Garlic.

Practitioner. Formula. Hawthorn 20ml; Lily of the Valley 10ml; Pulsatilla 5ml; Stone root 5ml; Barberry 5ml. Tincture Capsicum 1ml. Dose: Powders: 500mg (two 00 capsules or one-third teaspoon). Liquid extracts: 1 teaspoon. Tinctures: 2 teaspoons. Thrice daily in water or honey.

Prevention: Vitamin E – 400iu daily.

Diet. See: DIET – HEART AND CIRCULATION.

Supplements. Daily. Vitamin C, 2g. Vitamin E possesses anti-clotting properties, 400iu. Broad spectrum multivitamin and mineral including chromium, magnesium selenium, zinc, copper.

Acute condition. Strict bed-rest; regulate bowels; avoid excessive physical and mental exertion. Meditation and relaxation techniques dramatically reduce coronary risk. ... coronary heart disease

(thrombo-) combining form denoting 1. a blood clot (thrombus). 2. thrombosis. 3. blood platelets.... thromb

n. the dissolution of a blood clot (thrombus) by the infusion of a *fibrinolytic agent into the blood. It may be used in the treatment of *phlebothrombosis, *pulmonary embolism, and coronary thrombosis.... thrombolysis

(tPA, TPA) a natural protein, found in the body and able to be manufactured by genetic engineering, that can break up a thrombus (see thrombolysis). It requires the presence of *fibrin as a cofactor and is able to activate *plasminogen on the fibrin surface, which distinguishes it from the other plasminogen activators, *streptokinase and *urokinase. tPAs include reteplase and tenecteplase, given to treat acute myocardial infarction, and *alteplase.... tissue-type plasminogen activator

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

n. the introduction of a *catheter into a hollow organ or vessel. In urethral catheterization a catheter is introduced into the bladder through the urethra to relieve obstruction to the outflow of urine (see also intermittent self-catheterization). Catheters can also be passed above the pubis through the anterior abdominal wall (suprapubic catheterization) directly into a full bladder if urethral catheterization is not possible. Cardiac catheterization entails the introduction of special catheters into the chambers of the heart. This allows the measurement of pressures in the chambers and pressure gradients across the heart valves, as well as the injection of contrast medium for visualization of structures using X-rays (see coronary angiography). Vascular catheterization enables the introduction into the arteries or veins of: (1) contrast medium for angiography or venography; (2) drugs to constrict or expand vessels or to dissolve a thrombus (see thrombolysis); (3) metal coils or other solid materials to block bleeding vessels or to thrombose *aneurysms (see embolization); (4) devices for monitoring pressures within important vessels (e.g. *Swan-Ganz catheters for monitoring pulmonary artery pressure in critically ill patients); or (5) balloons and *stents to relieve obstruction.... catheterization

death of a segment of heart muscle, which follows interruption of its blood supply (see coronary thrombosis). Myocardial infarction is usually confined to the left ventricle. The patient experiences a ‘heart attack’: sudden severe chest pain, which may spread to the arms and throat. Although severe chest pain is the most widely recognized symptom of myocardial infarction, many patients – especially women – do not have chest pain. Other presenting symptoms include abdominal pain, nausea, vomiting, sweating, shortness of breath, and dizziness. The main danger is that of ventricular *fibrillation, which accounts for most of the fatalities. Other *arrhythmias are also frequent. Other complications include heart failure, rupture of the heart, phlebothrombosis, pulmonary embolism, pericarditis, shock, mitral regurgitation, and perforation of the septum between the ventricles.

Patients with myocardial infarction are best cared for in a specialized coronary care unit with facilities for the early detection, prevention, and treatment of arrhythmias and *cardiac arrest. Blockage of a major coronary artery is detected by elevation of the *S–T segment on the *electrocardiogram (STEMI or S–T elevation myocardial infarction). It is relieved by emergency *coronary angioplasty (commonly called primary *percutaneous coronary intervention) or the intravenous infusion of a drug to dissolve thrombus (*thrombolysis). Most survivors of myocardial infarction are able to return to a full and active life, including those who have been successfully resuscitated from cardiac arrest. Lesser degrees of coronary obstruction may not be seen on the electrocardiogram but are revealed by the detection of raised *troponin levels in the blood (NSTEMI or non-S–T elevation myocardial infarction). Treatment is with *antiplatelet drugs and early percutaneous coronary intervention.... myocardial infarction

a technique for demonstrating an abnormal blood supply to an organ by injecting a radioactive *tracer or *contrast medium. One of the most common uses, often in conjunction with ventilation scanning (see ventilation-perfusion scanning), is to detect obstruction of pulmonary arteries due to embolism by thrombus (see pulmonary embolism). Particles labelled with radioactive tracer are injected intravenously and become temporarily lodged in the capillaries in the lungs. Areas not being perfused show up as holes on the gamma-camera images. In *magnetic resonance imaging or *computerized tomography, contrast medium is injected and a series of images is obtained. The rate of change of enhancement is an index of the blood supply to the area of interest. This technique can be used to study blood supply to the brain, heart, or kidneys (in particular), to help diagnose arterial strictures or blockages, or tumours in which blood supply may be increased by abnormal vessels.... perfusion scan