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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The decision to anticoagulate patients with atrial fibrillation (AF) involves weighting the risk of an embolic event without therapy versus the risk of a hemorrhagic event on therapy. Improved methods of monitoring anticoagulation with the International Normalized Ratio (INR), and recent evidence of the efficacy and safety of low-dose warfarin (INR range 2.0 to 3.0) have clarified the role of anticoagulation in AF. Over the past four years, five large prospective randomized trials in patients with nonvalvular atrial fibrillation (NVAF) have reported substantial reductions in stroke in patients treated with low-dose warfarin therapy. The results of these trials, combined with previous studies, suggest that anticoagulation is the treatment of choice for patients with atrial fibrillation associated with rheumatic valvular disease, prosthetic valve disease, and now NVAF. Although the results of the prospective atrial fibrillation trials are very consistent in regard to the efficacy and safety of anticoagulation, there continues to be uncertainty regarding which subgroups of patients are at highest risk for embolic events. Subgroups that appear to be at high risk include patients with hypertension, previous embolic events, structural heart disease (enlarged left atrial size, previous myocardial infarction, left ventricular dysfunction), and older age. Young patients with no evidence of structural heart disease or hypertension (lone atrial fibrillation) have a low embolic rate and do not warrant anticoagulation. Recent studies suggest that there is little difference in the risk of stroke in patients with paroxysmal or chronic AF, therefore this factor should not have a major impact on therapeutic decisions. Anticoagulation is also recommended for patients undergoing elective cardioversion (recent onset of atrial fibrillation greater than two days in duration), and patients with atrial fibrillation and hyperthyroidism because of studies suggesting a higher rate of embolism if these patients are not anticoagulated. The role of aspirin in AF is less clear as only two of the five prospective trials randomized patients to aspirin therapy and only one documented aspirin benefit. Therefore, aspirin appears to offer less benefit but is a satisfactory alternative to warfarin therapy. Aspirin is currently recommend for patients who are poor candidates for anticoagulation or individuals with AF who are considered to be at low risk for stroke.
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PMID:Anticoagulation and atrial fibrillation. 845 50

Although sources of airborne lead have been reduced over the last decade, particularly with the use of lead-free gasoline, there are still relatively high levels of lead contamination in soils and the residential housing stock built before the 1970s, which pose a risk for continued direct exposure through ingestion or airborne exposure if resuspended. Neurobehavioral effects, particularly as a result of early childhood exposures, have been documented, and, because of the way lead is stored in the body, late effects can become manifest during periods of high bone turnover (e.g., pregnancy, lactation, or hyperthyroidism). Late consequences not only relate to lead excretion affecting the fetus or newborn but also appear to be associated with hypertension in adults. Control of exposure in early life is an important component of appropriate preventive action.
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PMID:Health effects of outdoor air pollution. Part 2. Committee of the Environmental and Occupational Health Assembly of the American Thoracic Society. 856 86

Recent literary case reports indicate that bromocriptine mesylate, when used for the suppression of lactation in the puerperium, can cause serious and even lethal side effects. The untoward sequelae are attributed to generalized or focal vasospasm affecting the cardiac and/or cerebral bold vessels. Apart from pre-existing hypertension and use in association with other ergot derivatives, the factors predisposing to such complications have not been elucidated, The authors present three atypical bromocriptine related postpartum accidents which may expand the understanding both of the predisposing factors and the potential consequences of bromocriptine related severe side effects. One of the cases raises the suspicion that the manifestations of hyperthyroidism may be aggravated by this method of pharmacologic ablactation. Another observation appears to imply that the drug may trigger the onset of chronic hypertension in women so predisposed. The development of cerebral infarcts, identified by MRI, in a clinically asymptomatic woman, exemplifies the threat of recurrent seizure activity in cases of bromocriptine related stroke.
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PMID:Bromocriptine related atypical vascular accidents postpartum identified through medicolegal reviews. 869 94

A newly diagnosed atrial fibrillation warrants a full investigation of the etiopathogenesis of this common arrhythmia. In the adult population, the most frequently associated conditions are systemic hypertension, coronary artery disease, mitral valvulopathy, congestive heart failure, and hyperthyroidism. Nevertheless, more infrequent and even rare, yet correctable, etiologies should not be overlooked. We describe three patients who presented to our hospital with a first episode of atrial fibrillation and who subsequently were demonstrated to have very unusual cardiovascular pathologies subtending this common arrhythmia. In all three cases, trans-esophageal echocardiography was instrumental in reaching an accurate diagnosis that was later confirmed at surgery.
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PMID:Uncommon etiologies of atrial fibrillation. 879 Sep 59

Previous reports of the follow-up of patients with atrial fibrillation have been confusing because of the variety of clinical presentations, heterogeneity of underlying pathology, and the initiation of follow-up at various stages of the patient's disease. The Canadian Registry of Atrial Fibrillation (CARAF) is a non-interventional, follow-up study of patients enrolled at the time of their initial diagnosis with atrial fibrillation at seven Canadian centres. At baseline, a comprehensive database recorded clinical, laboratory, and echocardiographic variables. No specific intervention was initiated and care was left to the attending physicians. Follow-up was performed at 3 months, 1 year, then annually. Echocardiograms were repeated every 2 years. Recurrence of atrial fibrillation, medical intervention, stroke, death, and other significant events have been specifically recorded. To date, 967 patients have been enrolled. Seven hundred and sixty-seven patients have been followed for 1 year, 468 for 2 years, and 217 for 3 years. Several studies have been undertaken on these patients. One study compared the variables of patients who were symptomatic with those who were asymptomatic. This study demonstrated that symptoms were more likely to occur if the patient were younger, had high blood pressure and high ventricular response during atrial fibrillation, and were female. These all achieve statistical significance and a formula was developed to predict the probability of symptoms in different subgroups of patients. Antiarrhythmic drug use was evaluated. Sotalol and propafenone were the most commonly used drugs and their use increased when atrial fibrillation was recurrent. Many patients initially received no antiarrhythmic drugs. Trends suggest that therapy is more aggressive with recurrence of the arrhythmia. The prevalence of thyroid abnormalities was investigated utilizing sensitive TSH measurements. This showed that overt hyperthyroidism is rare (1%) but laboratory abnormalities and history of thyroid dysfunction occurred more frequently, in 19% of patients. Another study evaluated antithrombotic therapy. Factors known to increase stroke risk, including congestive heart failure, previous stroke, and large left atrium all increased the use of anticoagulants. Anticoagulants were used more frequently in patients over the age of 65 and in patients with recurrent or chronic atrial fibrillation. There was concern that hypertension, shown to be a high predictor of stroke, did not result in a significant use of warfarin. Aspirin use was common in patients not placed on anticoagulants. Further studies are being undertaken with the ultimate goal to utilize baseline data to predict clinical outcomes.
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PMID:Follow-up of atrial fibrillation: The initial experience of the Canadian Registry of Atrial Fibrillation. 880 39

Beta adrenergic receptor blockers (beta-blockers) are an important class of drugs in the management of patients with cardiovascular diseases. These drugs have been shown to reduce mortality in hypertension and prolong survival in patients with coronary heart disease. Although hypertension and coronary heart disease account for the majority of excess cardiovascular morbidity and mortality in blocks, beta-blockers continue to be underprescribed in this ethnic group. The magnitude of blood pressure reduction in black patients with hypertension has been consistently less during monotherapy with nonselective beta-blockers than with diuretics. However, the highly selective beta-blocker bisoprolol has been shown to be as effective as diuretics and is equally effective in black and nonblack patients with hypertension. In general, no racial differences in efficacy are noted when beta-blockers are used with diuretics as combination therapy for hypertension. Black patients should not be denied beta-blocker therapy because of an anticipated suboptimal response, especially when there are clear indications for treatment (e.g., for migraine, hyperthyroidism, arrhythmia control, and after myocardial infarction).
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PMID:Use of beta-adrenergic receptor blockers in blacks. 893 Jul 72

Most patients with hypertension in the United States have essential (primary) hypertension (95%), the cause of which is unknown. The remaining 5% of adults with hypertension have the secondary form of hypertension, the cause and pathophysiologic process of which are known. Internists and other primary care physicians refer to this as treatable or curable hypertension, because the hypertension can be managed or even controlled with medications. Similarly, the condition is called surgical hypertension by surgeons in the belief that once the cause is determined and identified, surgical intervention will result in cure of hypertension. Secondary causes of hypertension include renal parenchymal disease, renovascular diseases, coarctation of the aorta, Cushing's syndrome, primary hyperaldosteronism, pheochromocytoma, hyperthyroidism, and hyperparathyroidism. Occasionally included in this category are alcohol- and oral contraceptive-induced hypertension and hypothyroidism, but these conditions are not discussed herein. The evaluation of secondary hypertension is of interest and can bring together different facets of anatomy, physiology, pharmacology, and radiology in the medical and surgical treatment of these disorders. Despite enthusiasm that can be generated in the evaluation of these conditions, evaluation can be expensive and should not be conducted for all patients with hypertension. Features that aid in the diagnosis of secondary hypertension include the following: 1. Onset of hypertension before the age of 20 or after the age of 50 years. The presence of hypertension at a young age may suggest coarctation of the aorta, fibromuscular dysplasia, or an endocrine disorder. Hypertension found for the first time after the age of 50 years may suggest the presence of renovascular hypertension caused by atherosclerosis. 2. Markedly elevated blood pressure or hypertension with severe end-organ damage, as in grade III or IV retinopathy. These findings suggest the presence of renovascular hypertension or pheochromocytoma. 3. Specific body habitus and ancillary physical findings. For example, truncal obesity and purple striae occur with hypercortisolism, and exophthalmos is associated with hyperthyroidism. 4. Resistant or refractory hypertension (poor response to medical therapy usually necessitating use of more than three antihypertensive medications from three different classes). 5. Specific biochemical test that suggest the existence of certain disorders, such as hypercalcemia in hyperparathyroidism, hyperglycemia in Cushing's syndrome and pheochromocytoma, and unprovoked hypokalemia with renin-producing tumors, primary hyperaldosteronism, or renin-mediated renovascular hypertension. 6. Other characteristics that may suggest secondary hypertension such as abdominal diastolic bruits (renovascular hypertension), decreased femoral pulses (coarctation of the aorta), or bitemporal hemianopias (Cushing's disease). A combination of a good history and physical examination, astute observation, and accurate interpretation of available data usually are helpful in the diagnosis of a specific causation.
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PMID:Secondary hypertension: evaluation and treatment. 894 19

The heart is a major target organ for thyroid hormone action, and marked changes occur in cardiac function in patients with hypothyroidism or hyperthyroidism. Triiodothyronine (T3)-induced changes in cardiac function can result from direct or indirect T3 effects. Direct T3 effects result from T3 action in the heart itself and are mediated by nuclear or extranuclear mechanisms. Extranuclear T3 effects, which occur independently of nuclear T3 receptor binding and increases in protein synthesis, influence primarily the transport of amino acids, sugars, and calcium across the cell membrane. Nuclear T3 effects are mediated by the binding of T3 to specific nuclear receptor proteins, which results in increased transcription of T3-responsive cardiac genes. The T3 receptor is a member of the ligand-activated transcription factor family and is encoded by cellular erythroblastosis A (c-erb A) genes. T3 increases the heart transcription of the myosin heavy chain (MHC) alpha gene and decreases the transcription of the MHC beta gene, leading to an increase of myosin V1 and a decrease in myosin V3 isoenzymes. Myosin V1, which is composed of two MHC alpha, has a higher myosin ATPase activity than myosin V3, which contains two MHC beta. The globular head of myosin V1, with its higher ATPase activity, leads to a more rapid movement of the globular head of myosin along the thin filament, resulting in an increased velocity of contraction. T3 also leads to an increase in the speed of diastolic relaxation, which is caused by the more efficient pumping of the calcium ATPase of the sarcoplasmic reticulum (SR). This T3 effect results from T3-induced increases in the level of the mRNA coding for the SR calcium ATPase protein, leading to an increased number of calcium ATPase pump units in the SR. Overall, T3 leads to an increase in ATP consumption in the heart. In addition, less chemical energy of ATP is used for contractile purposes and more of it goes toward heat production, which causes a decreased efficiency of the contractile process in the hyperthyroid heart. The pathophysiologic basis for myxedema is the opposite of that discussed for the hyperthyroid heart. In addition to decreased direct effects of thyroid hormone in cardiac myocytes, indirect effects occur through decreases in peripheral oxygen consumption and changes in hemodynamic parameters. Myofibrillar swelling with loss of striation and interstitial fibrosis occurs on histologic examination of hypothyroid hearts. In addition, accumulation of mucopolysaccharide substances (Glycosaminoglycans) can be demonstrated. On electron microscopic examination, mitochondria show disruption and lipid inclusion. Cardiac papillary muscle obtained from animals with hypothyroidism shows a depression of the force velocity curve and reduced rate of tension development, indicating significant contractile abnormalities. In patients with hypothyroidism, a true enhanced incidence of hypertension (increased peripheral vascular resistance) has been found. In addition, hypercholesterolemia and impairment of fatty acid mobilization are associated with myxedema and present additional risk factors for the development of atherosclerotic cardiovascular disease.
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PMID:[Cardiovascular effects of thyroid hormones]. 906 69

Hyperthyroidism is well known to be associated with cardiovascular manifestations. The authors have noted that patients of well controlled Graves' Disease often pose problems due to intrapoperative cardiovascular instability. Retrospective analysis of 137 case records of patients with Graves' disease (n = 35), toxic nodular goitre (n = 42) and those with euthyroid benign goitre (n = 60) were studied. In Graves' disease cardiovascular instability was found in the form of hypertension (n = 9) associated with tachyarrhythmia (n = 8) and bradycardia (n = 3). The incidence of first 2 of the above mentioned 3 problems was significantly higher in Graves disease (n = 9/35 patients) in contrast to a comparable group of patients with toxic nodular in (3/42 patients; P value 0.05) and euthyroid goiter (2/60 patients; P value < 0.001). Certain parameters such as high T3, T4 at the time of presentation were associated with higher incidence of these complications, in spite of very well controlled thyrotoxicosis. Whether heightened receptor sensitivity to catecholamines and higher renin-angiotensin activation explain these findings in Graves' disease, remains to be ascertained.
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PMID:Intraoperative hypertension during thyroidectomy for Graves' disease. 908 63

Hypothyroidism during pregnancy occurs in 1/1600-2000 deliveries, according to the most recent publications. The most common causes are chronic autoimmune thyroid disease, radiodine-131 treatment, or surgical removal. The diagnosis is difficult to make on clinical grounds alone, even in advanced cases, and a high index of suspicion is needed. Some women are at high risk of developing hypothyroidism, and they should be screened. These women may have had previous treatment for hyperthyroidism; high-dose neck irradiation, evidence of thyroid autoimmunity, amiodarone therapy, suspected hypopituitarism, and type I diabetics. The best laboratory test is the serum TSH, followed, if elevated, by a free T4 index and a TPO-ab titer. Thyroid antibodies have been associated with an increased (double) risk of miscarriage and postpartum thyroiditis. Frequent (22-44%) pregnancy-induced hypertension leading to preterm delivery, and prematurity is the main complication observed in those still hypothyroid near term. Proper therapy eliminates or reduces the risk. No congenital anomalies have been reported in the most recent studies, and the data available shows that both physical and mental development have been normal until children are 10 years old. However, one study reported lower IQs in children of euthyroid women with positive TPO-ab than in children of TPO-ab negative mothers. Levothyroxine is the treatment of choice. Euthyroidism must be reached and maintained in a timely fashion. Many women need more thyroxine during pregnancy, and surveillance of thyroid function is needed throughout gestation to make dose adjustments when needed. During the postpartum periods the thyroxine requirements decrease to preconception levels.
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PMID:Management of hypothyroidism during pregnancy. 910 50


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