Treatment consists of draining the ?uid (which may be blood or an e?usion) and treating the underlying cause.... tamponade
Shape and size In adults the heart is about the size and shape of a clenched ?st. One end of the heart is pointed (apex); the other is broad (base) and is deeply cleft at the division between the two atria. One groove running down the front and up the back shows the division between the two ventricles; a circular, deeper groove marks o? the atria above from the ventricles below. The capacity of each cavity is somewhere between 90 and 180 millilitres.
Structure The heart lies within a strong ?brous bag, known as the pericardium. Since the inner surface of this bag and the outer surface of the heart are both covered with a smooth, glistening membrane faced with ?at cells and lubricated by a little serous ?uid (around 20 ml), the movements of the heart are accomplished almost without friction. The main thickness of the heart wall consists of bundles of muscle ?bres, some of which run in circles right around the heart, and others in loops, ?rst round one cavity, then round the corresponding cavity of the other side. Within all the cavities is a smooth lining membrane, continuous with that lining the vessels which open into the heart. The investing smooth membrane is known as epicardium; the muscular substance as myocardium; and the smooth lining membrane as endocardium.
Important nerves regulate the heart’s action, especially via the vagus nerve and with the sympathetic system (see NERVOUS SYSTEM). In the near part of the atria lies a collection of nerve cells and connecting ?bres, known as the sinuatrial node or pacemaker, which forms the starting-point for the impulses that initiate the beats of the heart. In the groove between the ventricles and the atria lies another collection of similar nerve tissue, known as the atrioventricular node. Running down from there into the septum between the two ventricles is a band of special muscle ?bres, known as the atrioventricular bundle, or the bundle of His. This splits up into a right and a left branch for the two ventricles, and the ?bres of these distribute themselves throughout the muscular wall of the ventricles and control their contraction.
Openings There is no direct communication between the cavities on the right side and those on the left; but the right atrium opens into the right ventricle by a large circular opening, and similarly the left atrium into the left ventricle. Into the right atrium open two large veins, the superior and inferior venae cavae, with some smaller veins from the wall of the heart itself, and into the left atrium open two pulmonary veins from each lung. One opening leads out of each ventricle – to the aorta in the case of the left ventricle, to the pulmonary artery from the right.
Before birth, the FETUS’s heart has an opening (foramen ovale) from the right into the left atrium through which the blood passes; but when the child ?rst draws air into his or her lungs this opening closes and is represented in the adult only by a depression (fossa ovalis).
Valves The heart contains four valves. The mitral valve consists of two triangular cusps; the tricuspid valve of three smaller cusps. The aortic and pulmonary valves each consist of three semilunar-shaped segments. Two valves are placed at the openings leading from atrium into ventricle, the tricuspid valve on the right side, the mitral valve on the left, so as completely to prevent blood from running back into the atrium when the ventricle contracts. Two more, the pulmonary valve and the aortic valve, are at the entrance to these arteries, and prevent regurgitation into the ventricles of blood which has been driven from them into the arteries. The noises made by these valves in closing constitute the greater part of what are known as the heart sounds, and can be heard by anyone who applies his or her ear to the front of a person’s chest. Murmurs heard accompanying these sounds indicate defects in the valves, and may be a sign of heart disease (although many murmurs, especially in children, are ‘innocent’).
Action At each heartbeat the two atria contract and expel their contents into the ventricles, which at the same time they stimulate to contract together, so that the blood is driven into the arteries, to be returned again to the atria after having completed a circuit in about 15 seconds through the body or lungs as the case may be. The heart beats from 60 to 90 times a minute, the rate in any given healthy person being about four times that of the respirations. The heart is to some extent regulated by a nerve centre in the MEDULLA, closely connected with those centres which govern the lungs and stomach, and nerve ?bres pass to it in the vagus nerve. The heart rate and force can be diminished by some of these ?bres, by others increased, according to the needs of the various organs of the body. If this nerve centre is injured or poisoned – for example, by lack of oxygen – the heart stops beating in human beings; although in some of the lower animals (e.g. frogs, ?shes and reptiles) the heart may under favourable conditions go on beating for hours even after its entire removal from the body.... heart
Contents The trachea divides into right and left main bronchi which go to the two LUNGS. The left lung is slightly smaller than the right. The right has three lobes (upper, middle and lower) and the left lung has two lobes (upper and lower). Each lung is covered by two thin membranes lubricated by a thin layer of ?uid. These are the pleura; similar structures cover the heart (pericardium). The heart lies in the middle, displaced slightly to the left. The oesophagus passes right through the chest to enter the stomach just below the diaphragm. Various nerves, blood vessels and lymph channels run through the thorax. The thoracic duct is the main lymphatic drainage channel emptying into a vein on the left side of the root of the neck. (For diseases affecting the chest and its contents, see HEART, DISEASES OF; LUNGS, DISEASES OF; CHEST, DEFORMITIES OF.)... chest
Rheumatic fever is now extremely uncommon in developed countries, but remains common in developing areas. Diagnosis is based on the presence of two or more major manifestations – endocarditis (see under HEART, DISEASES OF), POLYARTHRITIS, chorea, ERYTHEMA marginatum, subcutaneous nodules – or one major and two or more minor ones – fever, arthralgia, previous attacks, raised ESR, raised white blood cell count, and ELECTROCARDIOGRAM (ECG) changes. Evidence of previous infection with streptococcus is also a criterion.
Clinical features Fever is high, with attacks of shivering or rigor. Joint pain and swelling (arthralgia) may affect the knee, ankle, wrist or shoulder and may migrate from one joint to another. TACHYCARDIA may indicate cardiac involvement. Subcutaneous nodules may occur, particularly over the back of the wrist or over the elbow or knee. Erythema marginatum is a red rash, looking like the outline of a map, characteristic of the condition.
Cardiac involvement includes PERICARDITIS, ENDOCARDITIS, and MYOCARDITIS. The main long-term complication is damage to the mitral and aortic valves (see HEART).
The chief neurological problem is chorea (St Vitus’s dance) which may develop after the acute symptoms have subsided.
Chronic rheumatic heart disease occurs subsequently in at least half of those who have had rheumatic fever with carditis. The heart valve usually involved is the mitral; less commonly the aortic, tricuspid and pulmonary. The lesions may take 10–20 years to develop in developed countries but sooner elsewhere. The heart valves progressively ?brose and ?brosis may also develop in the myocardium and pericardium. The outcome is either mitral stenosis or mitral regurgitation and the subsequent malfunction of this or other heart valves affected is chronic failure in the functioning of the heart. (see HEART, DISEASES OF).
Treatment Eradication of streptococcal infection is essential. Other features are treated symptomatically. PARACETAMOL may be preferred to ASPIRIN as an antipyretic in young children. One of the NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS) may bene?t the joint symptoms. CORTICOSTEROIDS may be indicated for more serious complications.
Patients who have developed cardiac-valve abnormalities require antibiotic prophylaxis during dental treatment and other procedures where bacteria may enter the bloodstream. Secondary cardiac problems may occur several decades later and require replacement of affected heart valves.... rheumatic fever
The superior vena cava starts at the top of the chest, close to the sternum, and passes down through the pericardium before connecting to the right atrium. It collects blood from the upper trunk, head, neck, and arms. The inferior vena cava starts in the lower abdomen and travels upwards in front of the spine, behind the liver, and through the diaphragm before joining the right atrium. It collects blood from the legs, pelvic organs, liver, and kidneys.... vena cava
Causes There is a major immunogenetic predisposition to rheumatoid arthritis in people carrying the HLA-DR4 antigen (see HLA SYSTEM). Other minor immunogenetic factors have also been implicated. In addition, there is a degree of familial clustering which suggests other unidenti?ed genetic factors. Genetic factors cannot alone explain aetiology, and environmental and chance factors must be important, but these have yet to be identi?ed.
Epidemiology Rheumatoid arthritis more commonly occurs in women from the age of 30 onwards, the sex ratio being approximately 4:1. Typical rheumatoid arthritis may occur in adolescence, but in childhood chronic SYNOVITIS usually takes one of a number of di?erent patterns, classi?ed under juvenile chronic arthritis.
Pathology The primary lesion is an in?ammation of the synovial membrane of joints. The synovial ?uid becomes diluted with in?ammatory exudate: if this persists for months it leads to progressive destruction of articular CARTILAGE and BONE. Cartilage is replaced by in?ammatory tissue known as pannus; a similar tissue invades bone to form erosions. Synovitis also affects tendon sheaths, and may lead to adhesion ?brosis or attrition and rupture of tendons. Subcutaneous and other bursae may be involved. Necrobiotic nodules also occur at sites outside synovium, including the subcutaneous tissues, the lungs, the pericardium and the pleura.
Clinical features Rheumatoid arthritis varies from the very mild to the severely disabling. Many mild cases probably go undiagnosed. At least 50 per cent of patients continue to lead a reasonably normal life; around 25 per cent are signi?cantly disabled in terms of work and leisure activities; and a minority become markedly disabled and are limited in their independence. There is often an early acute phase, followed by substantial remission, but in other patients gradual step-wise deterioration may occur, with progressive involvement of an increasing number of joints.
The diagnosis of rheumatoid arthritis is largely based on clinical symptoms and signs. Approximately 70 per cent of patients have rheumatoid factor ANTIBODIES in the SERUM but, because of the large number of false positives and false negatives, this test has very little value in clinical practice. It may be a useful pointer to a worse prognosis in early cases if the level is high. X-RAYS may help in diagnosing early cases and are particularly helpful when considering surgery or possible complications such as pathological fracture. Patients commonly develop ANAEMIA, which may be partly due to gastrointestinal blood loss from antiin?ammatory drug treatment (see below).
Treatment involves physical, pharmacological, and surgical measures, together with psychological and social support tailored to the individual patient’s needs. Regular activity should be maintained. Resting of certain joints such as the wrist with splints may be helpful at night or to assist prolonged manual activities. Sound footwear is important. Early use of antirheumatic drugs reduces long-term disability. Drug treatment includes simple ANALGESICS, NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS), and slow-acting drugs including GOLD SALTS (in the form of SODIUM AUROTHIOMALATE), PENICILLAMINE, SULFASALAZINE, METHOTREXATE and AZATHIOPRINE.
The non-steroidal agents are largely e?ective in reducing pain and early-morning sti?ness, and have no e?ect on the chronic in?ammatory process. It is important, especially in the elderly, to explain to patients the adverse effects of NSAIDs, the dosage of which can be cut by prescribing paracetamol at the same time. Combinations of anti-rheumatic drugs seem better than single agents. The slow-acting drugs take approximately three months to act but have a more global e?ect on chronic in?ammation, with a greater reduction in swelling and an associated fall in erythrocyte sedimentation rate (ESR) and rise in the level of HAEMOGLOBIN. Local CORTICOSTEROIDS are useful, given into individual joints. Systemic corticosteroids carry serious problems if continued long term, but may be useful under special circumstances. Much research is currently going on into the use of tumour necrosis factor antagonists such as INFLIXIMAB and etanercept, but their precise role remains uncertain.... rheumatoid arthritis
A chronic condition, endomyocardial fibrosis, is seen in Black Africans: the cause is unknown.... endomyocarditis
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