Lege Artis Medicinae

[Coumarin therapy]

PÉTERFY Miklós1

NOVEMBER 30, 1994

Lege Artis Medicinae - 1994;4(01 KLSZ)

[Coumarin oral anticoagulants are highly effective antithrombotic agents with relatively low risks of serious bleeding. Clinical uses and applications have evolved over the years. Recent changes include a, lower doses are used to treat most patients with thromboses, b, laboratory monitoring has been standardised thus intensities of anticoagulation are equivalent around the world, C, new indications for treatment have emerged from prospoective controlled clinical trials, for example profilaxis of embolic stroke in patients with chronic nonrheumatic atrial fibrillation. Coumarins inhibit the factors II, VII, IX, X and protein C and S. Traditionally the prothrombin time has been used to monitor the antithrombotic effects of the coumarins. The test is performed by the addition of a thromboplastin to recalcified plasma. The sensitivity of the thromboplastin to coumarin induced reduction in clotting factor activity is variable in the assay. Some thromboplastins are very sensitive, others are insensitive. Consequently, patients can receive different doses of coumarin depending on the thromboplastin used. To address this important clinical problem, the prothrombin time ratio is now modified by a factor (ISI) that reflects the „sensitivity" of the thromboplastin used and the result is termed International Normalised Ratio (INR). The main coumarin adverse effects (hae morrhage, teratogenicity and coumarin skin necroses and some special problems of coumarin therapy (diet, coumarin resistance, drug-drug interactions, the problem of over lapping heparin and coumarin, the problem of interval surgery) are also discussed.]

AFFILIATIONS

  1. Fővárosi Önkormányzat Péterfy Sándor Utcai Kórház, III. Belosztály

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Lege Artis Medicinae

[Introduction]

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[This LAM supplement was prompted by a very topical issue. Antithrombotic therapy has come to the forefront of the treatment of cardiovascular patients. Prolonged anticoagulant therapy involves mainly the use of coumarin derivatives, and platelet aggregation inhibition involves the extensive use of acetylsalicylic acid. The topicality of this issue can be approached from two angles. First, the incidence of ischaemic heart disease and cerebrovascular disease in the developed world is alarmingly high.]

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[All 3 methods of antithrombotic therapy have a role in the primary and secondary prevention of cardiogenic thromboembolism. The most important modality is anticoagulant treatment which is indicated now in the majority of cases of nonvalvular atrial fibrillation. An tiplatelet therapy is of limited value in cardiogenic thromboembolism. The expanded clinical use of both kinds of treatment depends on increased safety and unchanged efficacy which can be achieved by reduced dosage and the combination of the two therapeutic methods. Thrombolytic therapy, until recently, has been limited to the thromboembolic diseases of the right heart. Presently, thrombolysis is being more and more often used in the lifesaving treatment of left sided prosthetic valve thrombosis. ]

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TEMESVÁRI András

[Echocardiography is the method of choice to detect the cardiac source of embolism. Trans thoracic echocardiography is preferred for the diagnosis of left ventricular thrombus. Trans esophageal echocardiography is more sensitive than transthoracic echocardiography in the detection of possible sources of systemic emboli (41-65% versus 14–37%). Left atrial and appendage thrombus, spontaneous echocontrast, patent foramen ovale, atrial septum aneurysm, left atrial myxoma and prosthetic valve thrombus are more frequently demonstrated by transeso phageal echocardiography. Right atilai and ventricular thrombus, embolus in the pulmonary artery, patent foramen ovale and pulmonary hypertension should be examined in pulmonary embolism. ]

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[The practice and indication of anticoagulation in the care of cerebrovascular patients is still controversial. It is hoped that improved diagnostic facilities, the extensive use of imaging techniques, more accurate assessment and monitoring of haemostasis, and the increasing number of multicentre studies will help us to better define the conditions for treatment. The use of anticoagulant therapy may be justified in stroke prevention, mainly to prevent cardioembolisation in cases where the probability of stroke is higher than 5%, and in cerebral venous thrombosis and deep vein thrombosis. The use of anticoagulation in the treatment of progressive ischaemic stroke is still controversial. The experience with heparin (coumarins, warfarin) has been well established, whereas there is currently a lack of data and extensive clinical trials on the use of low molecular weight heparins, heparinoids. ]

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