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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombus formation depends on adherence of blood-formed elements to the intimal surface through platelet-vessel surface interaction, platelet release phenomena and aggregation, formation of fibrin, and the enmeshing of blood cells. Arterial thrombi involve platelet aggregation, whereas venous thrombi found in low flow or during stasis have greater proportions of erythrocytes and fibrin. It is not known if or how abnormalities of flow resistance, platelet thrombus formation, or endothelial and dynamic parameters affect the microcirculation, largely due to the difficulty of obtaining comprehensive data from these systems. Increases of fibrinogen observed in many disorders may result in minor changes in blood viscosity without known physiologic consequence, but in most disorders in which thrombosis is observed, the pathophysiologic mechanisms are multifactorial and abnormal blood viscosity is presumed to be a significant but not limiting component. Therapeutic approaches in thrombotic disorders should recognize which elements of the thrombotic triad predominate. In arterial disorders focus should be on platelet activity, and the objectives of venous thrombosis treatment include prevention of morbidity and death from pulmonary embolism, reduction of morbidity resulting from the acute thrombotic episode, and prevention of the postphlebitic syndrome. Pathology, mechanism, and treatment for specific thrombogenic disorders are described. Treatments suggested for hyperviscosity involve giving antibiotics during crises. Also discussed are thalassemia, paroxysomal nocturnal hemoglobinuria, polycythemia, cryoglobulinemia, paraproteinemia, diabetes mellitus, and disseminated intravascular coagulation. Studies have established a relationship between thromboembolic disease and oral contraceptives (OCs). The risk is only increased while the patient is taking OCs but is compounded in women undergoing surgery or who have a disorder which predisposes to venous disease. The risk for myocardial infarction or stroke is significantly increased when OCs are taken over age 35 and when there is hypertension, smoking, type-II hyperlipoproteinemia, and diabetes mellitus. The risk appears to be a function of estrogen dosage, causing a 25% mean increase in calf venous volume and 30% decrease in vein velocity of venous blood compared to controls. Low flow rates may contribute to venous thromboembolism. OCs may alter precisely regulated systems of coagulation and fibrinolysis and recent studies confirm abnormalities in the hemostatic system attributed to OCs. 16% of women taking OCs have a 60% or greater reduction in antithrombin III activity. The multiple effects of OCs often result in low-grade activation of the hemostatic system, potentially lowering the threshold to precipitate thrombus formation and possibly explaining the increased incidence of thromboembolic disease. Heparin appears to reverse many of these problems.
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PMID:Blood viscosity and thrombosis: clinical considerations. 676 12

The use of estrogen replacement therapy in postmenopausal women is under close scrutiny. The indications and side effects of replacement therapy are reviewed, and recommendations regarding its use are made. Hot flashes, atrophy of the vaginal epithelium, and prevention of osteoporosis have been established as indications for estrogen replacement therapy. Prevention of cardiovascular disease, aging changes of skin, and the occurrence of mental illness have also been suggested as indications, but beneficial effects of estrogen replacement therapy for these problems have not been clearly established. Studies have shown that side effects of estrogen replacement therapy include endometrial cancer, hypertension, gallbladder disease, and angina pectoris. Breast cancer may also be a risk factor, but a consensus of opinion has not been established. Pulmonary embolism, cerebral vascular accident, or myocardial infarction has not been associated with estrogen replacement therapy. The use of progesterone with estrogen replacement therapy has been shown to reduce the occurrence rate of endometrial carcinoma, but it does not prevent all the actions of estrogen. Oral administration of estrogen is the preferred route despite misgivings about portal absorption and liver metabolism. Further studies must examine this question. Various agents have been shown to be effective in treating some climacteric symptoms. These include progesterone for hot flashes and calcium for the prevention of osteoporosis. Other agents may also be effective but have not been tested critically.
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PMID:Estrogen replacement therapy. 702 79

The question of whether the formulation of the oral contraceptive (OC) pill makes any clinically significant difference is often raised because both physicians and patients are faced with the problem of selecting from a bewildering array of available pills. The answer involves examining the contribution of estrogen and progestin separately. The estrogen component of the combination birth control pill serves 3 important functions: it exerts negative feedback action on the secretion of gonadotropins; it provides stability to the endometrium, preventing irregular shedding and unwanted breakthrough bleeding; and it increases the potency of the progestational component in its inhibitory action on gonadotropin secretion and its antifertility effects on cervical mucus, endometrium, and possibly the Fallopian tube. The presence of estrogen may eliminate a need for higher progestin doses in OCs. This effect is mediated by estrogen induced increase in the concentration of intracellular progestin receptors. A minimal pharmacologic level of estrogen is needed to achieve effective contraception, and the new low dose pills are most likely at the limit of the ability to reduce dosage. Thrombosis is the most serious side effect of the OC; it plays a key role in the increased risk of death from a variety of circulatory problems such as myocardial infarction, pulmonary embolism, and stroke. A convincing argument can be made for a dose related response between the incidence of thrombosis and the estrogen content of the pill. Only the 19-nortestosterone family of progestins is approved for contraceptive use in the U.S. The progestin component exerts its principal contraceptive effect by suppressing luteinizing hormone (LH) secretion. In 1978 an early report from the Walnut Creek study suggested that HDL-cholesterol levels were positively associated with estrogen levels in OCs and negatively with progestin. The implication was that high dose progestins would be associated with a greater risk of cardiovascular diseases. A recent report suggests that the estrogen and progestin components could be balanced to produce minimal effects on lipid metabolism. Current evidence supports the view that there is greater safety with pills containing less than 50 mcg of estrogen. The side effects of amenorrhea and breakthrough bleeding are reviewed. It is cautioned that if an older woman chooses to use OC, she should be aware of the higher risk involved with increasing age.
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PMID:The formulation of oral contraceptives: does the amount of estrogen make any clinical difference? 704 35

Four drugs that inhibit platelet function have been evaluated for their antithrombotic effects in humans. These are aspirin, dipyridamole, hydroxychloroquine and sulphinpyrazone. Aspirin has been shown to reduce the number of transient ischemic attacks (TIA), stroke and death in patients with multiple TIA. The reduction in TIA was greatest in males who were normotensive and when there was an angiographically demonstrated lesion in the carotid artery that accounted for the symptoms. Aspirin reduced venous thrombosis and non-fatal and fatal pulmonary embolism in patients after surgery for fractured hip and after elective hip replacement. There is evidence that the prophylactic effect of aspirin may be greater in male patients. Aspirin reduced the frequency of arteriovenous shunt thrombosis. Aspirin abolished symptoms in patients with peripheral ischemia associated with thrombocytosis and spontaneous platelet aggregation. There is no conclusive evidence at the present time that aspirin is effective in patients with coronary artery artery disease. Dipyridamole in combination with oral anticoagulants is effective in reducing the frequency of systemic embolism in patients with prosthetic heart valve replacement but is ineffective in patients with transient cerebral ischemic attacks or for the prevention of venous thromboembolism. Hydroxychloroquine was effective in reducing postoperative venous thrombosis in patients undergoing general abdominothoracic surgery but the evidence that it was effective in patients undergoing orthopaedic surgery is inconclusive. Sulphinpyrazone may be effective in reducing the frequency of sudden cardiac deaths in patients in the first year after myocardial infarction when it is started within 25 to 35 days after the infarction. Sulphinpyrazone reduced the incidence of arteriovenous shunt thrombosis in patients undergoing chronic hemodialysis and in combination with anticoagulants, it reduced the frequency of recurrent venous thrombosis. There have been no large scale trials of platelet suppressant drugs in clinical cancer and successful treatment of thromboembolic disorders cannot be used to predict success in the treatment of malignant disease.
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PMID:Antithrombotic effects of drugs which suppress platelet function: their potential in prevention growth of tumour cells. 705 Oct 35

Maternal mortality was examined in a semi-urban Nigerian community over a 10-year period. Maternal mortality was defined as death occurring as the direct result of childbearing and measured per 1000 births. Abortions at below 20 weeks gestation were excluded. From 1966 to 1975, there were 90 maternal deaths out of 13,182, a rate of 6.8/1000. The hospital records of the Baptist Medical Center, located in the western part of Nigeria, were carefully reviewed and cross-checked with obstetric statistical records. Only 13 of the deaths occurred in hospitalized patients. 78 (80%) were due to direct obstetric causes; 12% were from nonobstetric causes. Anemia due to blood loss was the leading casue of death, accounting for 30, or 33%, of the deaths. Anemia, with or without congestive heart failure accounted for 7 deaths. Infection was responsible for 5 deaths. Ruptured uterus, preeclampsia, and eclampsia occurred in equal percentages, 10-11%. Indirect obstetric deaths, such as sudden death, accounted for 10 deaths. 50% of these were anesthetic deaths; the remainder were due to pulmonary embolism. Sickle cell intrapartum crisis was the cause of 1 death. Associated causes included featured pneumonia, nephritis, hepatitis, meningitis, enteritis, and cerebrovascular accident. Parity ranged from 0-11. 25 babies were salvaged in this series. Prevention continues to be the cornerstone in improving maternal mortality figures in developing countries. The Baptist Medical Center's model for providing maternal care is described briefly and is identified as responsible for the encouraging decline in the maternal mortality rate.
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PMID:Maternal mortality in a semi-urban Nigerian community. 720 76

Clinicopathologic correlations were reviewed in 100 cases of recent cerebral infarctions in the internal carotid artery distribution. The most frequent cause of death was transtentorial herniation, followed in frequency by pneumonia, cardiac causes, and pulmonary embolism. Thirty-six percent of all patients and 47% of those with transtentorial herniation died within 48 hours of cerebral infarction. Of the treatable extracerebral causes of death determined at autopsy, only 34% were recorded premortem in the clinician's death summary.
Stroke
PMID:Mechanisms and timing of deaths from cerebral infarction. 731 70

The effectiveness of low-dose subcutaneous heparin in the prophylaxis of deep vein thrombosis in patients with ischemic stroke was investigated in an unblinded controlled study. The frequency of deep vein thrombosis and pulmonary embolism in the control group was 23% versus 2% in the patients receiving heparin. There were no bleeding complications in the test group and there were no differences in the occurrence of hemorrhage changes in the cerebral ischemic infarction in both groups.
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PMID:Effects of low-dose subcutaneous heparin on the occurrence of deep vein thrombosis in patients with ischemic stroke. 738 75

During an 8-month study of stroke patients, a 9% incidence of pulmonary embolism and a 1.5% incidence of thrombophlebitis was found among hemiparetic patients undergoing intensive rehabilitation after being medically stabilized. Patients were usually studied 10 days to 2 weeks after the onset of stroke. During the next 18 months, 141 subsequent patients were studied with 125I-fibrinogen uptake leg scans, disclosing a 29% incidence of deep venous thrombosis. Venograms were obtained in 28 patients; clots in 25 patients were confirmed in normal locations on the fibrinogen scan, and there was 1 false negative and 2 false positives. The subsequent 14 patients with clot were anticoagulated on the basis of the fibrinogen scan alone. Early anticoagulation of clinically silent leg thrombi prevented any pulmonary emboli.
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PMID:Pulmonary embolism in stroke: prevention by early heparinization of venous thrombosis detected by iodine-125 fibrinogen leg scans. 745 23

Thrombolytic therapy mimics and enhances physiological fibrinolysis. The following substances are presently available for clinical use: the nonphysiological thrombolytics streptokinase, the APSAC (acylated plasminogen-streptokinase activator complex), the physiological plasminogen activators urokinase and tissue plasminogen activator (t-PA). Whereas the first three systematically activate the fibrinolytic system, t-PA possesses relative fibrin selectivity. The fibrin-selective active pro-urokinase has not yet been officially approved for the treatment of thromboembolic diseases, but it is being clinically tested. Fibrinolytic therapy has an established place in the management of acute myocardial infarction and of massive pulmonary embolism. When an acute deep venous thrombosis is diagnosed with a proximal extension into the popliteal vein, thrombolytic therapy is clearly superior to heparin. The lysis has proven to be an effective form of treatment of peripheral occlusive arterial disease. Local thrombolytic therapy is an option for acute and chronic femoro-popliteal occlusions involving the trifurcation into the calf arteries and for embolic occlusions of the same segment in patients with contraindications to surgical therapy. First study results of thrombolytic therapy of stroke are promising.
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PMID:[Fibrinolytic agents--who benefits when?]. 748 76

Cisplatin-based chemotherapy considerably improved the outcome of patients with metastatic germ cell tumors. Apart from Raynaud's phenomenon, a frequent side effect, vascular toxicity associated with chemotherapy for testicular cancer, has not been described precisely. Although major vascular complications such as myocardial infarction, stroke and pulmonary embolism seem to occur infrequently, they raise concern with regard to the safety of chemotherapy. Also, potential late vascular toxicity has to be taken into account. Whereas a cause and effect relationship is probable for some vascular events following chemotherapy, some cases may represent coincidence or may be disease related. Presently, the very low incidence of major vascular events should not enter into therapeutic decisions.
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PMID:Vascular toxicity associated with chemotherapy for testicular cancer. 753 46


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