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Encyclopedia > Arterial hypertension

Arterial hypertension, or high blood pressure is a medical condition where the blood pressure is chronically elevated. Persistent hypertension is one of the risk factors for strokes, heart attacks and heart failure, and is a leading cause of chronic renal failure. Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. ... A stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is suddenly interrupted by occlusion (an ischemic stroke- approximately 90%of strokes) or by hemorrhage (a hemorrhagic stroke - approximately 10% of strokes). ... A myocardial infarction occurs when an atherosclerotic plaque slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, totally occluding the artery and preventing blood flow downstream. ...

Contents

Definition

Blood pressure is a continuous variable, and risks of various adverse outcomes rise with it. Hypertension is usually diagnosed on finding blood pressure above 140/90 mmHg measured on both arms on three occasions over a few weeks. (Also see 'Hypertensive urgencies and emergencies' below). Recently, the JNC VII (The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure) has defined blood pressure over 120/80 mmHg and below 140/90 mmHg as "pre-hypertension". "Prehypertension is not a disease category. Rather, it is a designation chosen to identify individuals at high risk of developing hypertension (JNC VII)." Normal blood pressure is 120/80 mmHg. Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. ...


In patients with diabetes mellitus or kidney disease studies have shown that blood pressure over 130/80 mmHg should be considered a risk factor and may warrant treatment. Diabetes mellitus is a medical disorder characterized by varying or persistent hyperglycemia (elevated blood sugar levels), especially after eating. ...


Etiology

Essential hypertension

  • Age. Over time, the number of collagen fibres in artery and arteriole walls increases, making blood vessels stiffer. With the reduced elasticity comes a smaller cross-sectional area in systole, and so a raised mean arterial blood pressure.
  • High salt intake
  • Sedentary lifestyle
  • Tobacco smoking
  • Alcohol abuse
  • High levels of saturated fat in the diet
  • Obesity. In obese subjects, losing a pound in weight generally reduces blood pressure by 1mmHg.
  • Stress
  • Low birth-weight
  • Diabetes mellitus
  • Various genetic causes

In essential hypertension Collagen is the main protein of connective tissue. ... In chemistry, salt is a general term used for ionic compounds composed of positively charged cations and negatively charged anions, so that the product is neutral and without a net charge. ... Tobacco smoking is the act of smoking tobacco products, especially cigarettes and cigars. ... This article needs cleanup. ... A saturated fat is a fat or fatty acid in which there are no double bonds between the carbon atoms of the fatty acid chain (hence, it is fully saturated with hydrogen atoms). ... Diabetes mellitus is a medical disorder characterized by varying or persistent hyperglycemia (elevated blood sugar levels), especially after eating. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ...

Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... Renal artery stenosis is the narrowing of the renal artery. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... Many drugs are provided in tablet form. ... In general usage, alcohol (from Arabic al-khwl الكحول, or al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). ... Non-steroidal anti-inflammatory drugs, usually abbreviated to NSAIDs, are drugs with analgesic, antipyretic and anti-inflammatory effects - they reduce pain, fever and inflammation. ... Monoamine oxidase inhibitors (MAOIs) are a class of antidepressant drugs prescribed for the treatment of depression. ... The adrenergic receptors (or adrenoceptors) are a class of G_protein coupled receptors that is the target of catecholamines. ... Oral contraceptives are chemicals taken by mouth to inhibit normal fertility. ... The largest artery in the human body, the aorta originates from the left ventricle of the heart and brings oxygenated blood to all parts of the body in the systemic circulation. ... In medicine, a persons pulse is the throbbing of their arteries as an effect of the heart beat. ... Anemia (American English) or anaemia (Commonwealth English), which literally means without blood, is a lack of red blood cells and/or hemoglobin. ... Fever, also known as pyrexia, is a medical symptom which describes an increase in temperature to levels which are above normal (37 degrees Celsius, 98. ... In anatomy, the heart valves are valves in the heart that prevent blood from flowing the wrong way. ...

Pathophysiology

The mechanisms behind the factors associated with inessential hypertension are generally fully understood, and are outlined below. However, those associated with essential hypertension are far less understood. What is known is that cardiac output is raised early in the disease course, with total peripheral resistance normal; over time cardiac output drops to normal levels but TPR is increased. Three theories have been proposed to explain this: Cardiac output is the volume of blood being pumped by the heart in a minute. ... Total peripheral resistance refers the cumulative resistance of the thousands of arterioles in the body, or the lungs, respectively. ...

  • Inability of the kidneys to excrete sodium, resulting in natriuretic factor (note: the existence of this substance is theoretical) being secreted to promote salt excretion with the side-effect of raising total peripheral resistance.
  • An overactive renin / angiotension system leads to vasoconstriction and retention of sodium and water. The increase in blood volume leads to hypertension.
  • An overactive sympathetic nervous system, leading to increased stress responses.

Inessential hypertension

  • Pregnancy: unclear.
  • Kidney disease / renal artery stenosis: the normal physiological response to low blood pressure in the renal arteries is to increase cardiac output to maintain the pressure needed for glomerular filtration. Here, however, increased CO can't solve the structural problems causing renal artery hypotension, with the result that CO remains chronically elevated.
  • Cancers: tumours in the kidney can operate in the same way as kidney disease. More commonly, however, tumours cause inessential hypertension by ectopic secretion of hormones involved in normal physiological control of blood pressure.
  • Drugs: anything with an adrenergic effect causes vasoconstriction at sites with alpha-adrenoceptors, increasing total peripheral resistance.
  • Malformed aorta, slow pulse: these cause reduced blood flow to the renal arteries, with physiological responses as already outlined.
  • Anemia: unclear.
  • Fever: unclear.
  • Aortic valve disease: unclear.

The glomerulus is a capillary bed found surrounded by the Bowmans capsule of the nephron in the vertebrate kidney. ...

Signs and symptoms

Hypertension

Hypertension is usually found incidentally - "case finding" by healthcare professionals. It normally produces no symptoms.


Malignant hypertension (or accelerated hypertension) is distinct as a late phase in the condition, and may present with headaches, blurred vision and end-organ damage. Malignant hypertension is a complication of hypertension characterized by very elevated blood pressure, and organ damage in the eyes, brain, lung and/or kidneys. ...


It is recognised that stressful situations can increase the blood pressure; if a normally normotensive patient has a high blood pressure only when being reviewed by a health care professional, this is colloquially termed white coat effect. Since most of what we know of hypertension and its outcome with or without modification is based on large series of readings in doctors' offices and clinics (eg Framingham) it is difficult to be sure of the significance of white-coat hypertension. Ambulatory monitoring may help determine whether traffic and ticket inspectors produce similar sustained rises.


Hypertension is often confused with mental tension, stress and anxiety. While chronic anxiety is associated with poor outcomes in people with hypertension, it alone does not cause it.


Hypertensive urgencies and emergencies

Hypertension is rarely severe enough to cause symptoms. These only surface with a systolic blood pressure over 240 mmHg and/or a diastolic blood pressure over 120 mmHg. These pressures without signs of end-organ damage (such as renal failure) are termed accelerated hypertension. When end-organ damage is present, but in absence of raised intracranial pressure, it is called hypertensive urgency. Hypertension under this circumstance needs to be controlled, but hospitalization is not required. When hypertension causes increased intracranial pressure, it is called malignant hypertension. Increased intracranial pressure causes papilledema, which is visible on ophthalmoscopic examination of the retina. In medicine, hypertension is abnormally high blood pressure. ... Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. ... Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. ... Intracranial pressure is the pressure of the cerebrospinal fluid within the central nervous system. ... Malignant hypertension is a complication of hypertension characterized by very elevated blood pressure, and organ damage in the eyes, brain, lung and/or kidneys. ... Papilledema is optic disc swelling that is caused by increased intracranial pressure. ... In medicine the ophthalmoscope was invented by Hermann von Helmholtz and is an instrument that is used to look into the human eye. ... Human eye cross-sectional view. ...


Complications

While elevated blood pressure alone is not an illness, it often requires treatment due to its short- and long-term effects on many organs. The risk is increased for:

A stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is suddenly interrupted by occlusion (an ischemic stroke- approximately 90% of strokes), by hemorrhage (a hemorrhagic stroke - less than 10% of strokes) or other causes. ... A myocardial infarction occurs when an atherosclerotic plaque slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, totally occluding the artery and preventing blood flow downstream. ... Hypertension, or high blood pressure that does not respond to treatment, has several ocular manifestations. ... Human eye cross-sectional view. ... In kidney, as a result of benign arterial hypertension, hyaline (pink, amorphous, homogeneous material) accumulates in the wall of small arteries and arterioles, producing the thickening of their walls and the narrowing of the lumens - hyaline arteriolosclerosis. ...

Pregnancy

See the main article: hypertension of pregnancy Pregnancy-induced hypertension (PIH) is the accepted name for what was previously called gestational hypertension or hypertension of pregnancy. ...


Although few women of childbearing age have high blood pressure, up to 10% develop hypertension of pregnancy. While generally benign, it may herald three complications of pregnancy: pre-eclampsia, HELLP syndrome and eclampsia. Follow-up and control with medication is therefore often necessary. Pregnancy-induced hypertension (PIH) is the accepted name for what was previously called gestational hypertension or hypertension of pregnancy. ... Pre-eclampsia (previously called toxemia) is a hypertensive disorder of pregnancy. ... HELLP syndrome is a life-threatening complication of pre-eclampsia. ...


Diagnosis

The diagnosis of hypertension is by definition made by three separate measurements at least one week apart. Two caveats to this criteria is it must be in the presence mild elevations and in the absence of end organ damage. If either are not met, the diagnosis may be made without repeat measurements in some cases.


Obtaining reliable blood pressure measurements relies on following several rules and being cognizant of the many factors that influence blood pressure reading.


For instance, measurements should be at least 1 hour after caffeine, 30 minutes after smoking and without any stress. Cuff size is also important. The bladder should encircle and cover two-thirds of the length of the arm. The patient should be sitting for a minimum of five minutes. The patient should not be on any adrenergic stimulants, such as those found in many cold medications.


When taking manual measurements, the person taking the measurement should be careful to inflate the cuff at least 30 mmHg greater than systolic pressure. A stethoscope should be placed lightly over the brachial artery. The arm should be at the level of the heart and the cuff should be deflated at a rate of 2-3 mmHg/sec. Systolic pressure is the pressure reading at the onset of sounds. Diastolic pressure is then defined as the pressure at which the sounds disappear. Two measurements should be made at least 5 minutes apart and if there is a discrepancy of more than 5 mmHg, a third reading should be done. The readings should then be averaged. An initial measurement should include both arms. Also, in elderly patients, it is recommended to measure pressures in multiple postures as they are at risk for orthostatic hypotension.


Once the diagnosis of hypertension has been made it is important to attempt to identify reversible (secondary) causes. In the adult population over 90% of all hypertension has no known cause and is therefore called "essential/primary hypertension". Often, it is part of the metabolic "syndrome X" in patients with insulin resistance: it occurs in combination with diabetes mellitus (type 2), combined hyperlipidemia and central obesity. However, in the pediatric population the opposite is true, most cases have a secondary cause and these should be pursued more aggresively. Metabolic syndrome is a combination of medical disorders that affect a large number of people in a clustered fashion. ... In medicine, insulin resistance denotes a decompensation of glucose homeostasis where the tissues appear to be less responsive to insulin. ... Diabetes mellitus is a medical disorder characterized by varying or persistent hyperglycemia (elevated blood sugar levels), especially after eating. ... In medicine, combined hyperlipidemia (or -aemia) is a commonly occurring form of hypercholesterolemia (elevated cholesterol levels) characterised by increased LDL and triglyceride concentrations, often accompanied by decreased HDL. On lipoprotein electrophoresis (a test now rarely performed) is shows as a hyperlipoproteinemia type IIB. The elevated triglyceride levels (>5 mmol/l... Central obesity (or apple-shaped or masculine obesity), is when the main deposits of body fat are localised around the abdomen and the upper body. ...


Important causes of secondary hypertension are:

Blood tests commonly performed in a newly diagnosed hypertension patient are: Alcoholic beverages are drinks containing ethanol. ... Renal artery stenosis is the narrowing of the renal artery. ... This article needs cleanup. ... A pheochromocytoma (also phaeochromocytoma, English spelling) is a tumor in the medulla of the adrenal glands (or, rarely, the ganglia of the sympathetic nervous system) which secretes excessive amounts of catecholamines, usually epinephrine and norepinephrine. ... Conns syndrome is overproduction of the mineralocorticoid hormone aldosterone by the adrenal glands. ... Cushings syndrome or hypercortisolism is an endocrine disorder caused by excessive levels of the endogenous corticosteroid hormone cortisol. ... A steroid is a lipid characterized by a carbon skeleton with four fused rings. ... Scleroderma is a rare, chronic disease characterized by excessive deposits of collagen. ... In medicine (endocrinology), hyperparathyroidism is overactivity of the parathyroid glands and excess production of parathyroid hormone (PTH). ... Species Glycyrrhiza acanthocarpa Glycyrrhiza aspera Glycyrrhiza astragalina Glycyrrhiza bucharica Glycyrrhiza echinata Glycyrrhiza eurycarpa Glycyrrhiza foetida Glycyrrhiza glabra Glycyrrhiza iconica Glycyrrhiza korshinskyi Glycyrrhiza lepidota Glycyrrhiza pallidiflora Glycyrrhiza triphylla Glycyrrhiza uralensis Glycyrrhiza yunnanensis Ref: ILDIS Version 6. ... Blood tests are laboratory tests done on blood to gain an appreciation of disease states and the function of organs. ...

Creatinine is a breakdown product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body (depending on muscle mass). ... In medicine (nephrology) renal function is an indication of the state of the kidney and its role in physiology. ... An electrolyte is a substance which dissociates free ions when dissolved (or molten), to produce an electrically conductive medium. ... General Name, Symbol, Number sodium, Na, 11 Series alkali metal Group, Period, Block 1 (IA), 3, s Density, Hardness 968 kg/m3, 0. ... General Name, Symbol, Number potassium, K, 19 Series alkali metals Group, Period, Block 1(IA), 4, s Density, Hardness 856 kg/m3, 0. ... A space-filling model of glucose Glucose, a simple monosaccharide sugar, is one of the most important carbohydrates and is used as a source of energy in animals and plants. ... Diabetes mellitus is a medical disorder characterized by varying or persistent hyperglycemia (elevated blood sugar levels), especially after eating. ... Cholesterol is a steroid lipid, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ...

Epidemiology

The level of blood pressure regarded as deleterious has been revised down during years of epidemiological studies. A widely quoted and important series of such studies is the Framingham Heart Study carried out in an American town: Framingham, Massachusetts. The results from Framingham and of similar work in Busselton, Western Australia have been widely applied. To the extent that people are similar this seems reasonable, but there are known to be genetic variations in the most effective drugs for particular sub-populations. Recently (2004) the Framingham figures have been found to overestimate risks for the UK population considerably. The reasons are unclear. Nevertheless the Framingham work has been an important element of UK health policy. The Framingham Heart Study is a cardiovascular study based in Framingham, Massachusetts. ... Framingham is a town located in Middlesex County, Massachusetts, USA. As of the 2000 census, the town had a total population of 66,910, making it the most populous town in Massachusetts, and at present, the largest town in North America. ... 2004 is a leap year starting on Thursday of the Gregorian calendar. ...


Treatment

Doctors recommend weight loss and regular exercise, as well as discontinuing smoking, as the first steps in treating mild to moderate hypertension. These steps are highly effective in reducing blood pressure. Unfortunately these actions are easier to suggest than to achieve and most patients with moderate or severe hypertension end up requiring indefinite drug therapy to bring their blood pressure down to a safe level. In the context of physical health, weight loss is the process of losing body weight, usually by losing fat. ... The word exercise can mean the following: A setting in action or practicing. ... Tobacco smoking is the act of smoking tobacco products, especially cigarettes and cigars. ...


Mild hypertension is usually treated by diet, exercise and improved physical fitness. A diet rich in fruits and vegetables and fat-free dairy foods and low in fat and sodium lowers blood pressure in people with hypertension. Dietary sodium (salt) causes hypertension in some people and reducing salt intake decreases blood pressure in a third of people. Regular mild exercise improves blood flow, and helps to lower blood pressure. Dieting is the practice or habit of eating (and drinking) in a regulated fashion, usually with the aim of losing weight. ... General Name, Symbol, Number sodium, Na, 11 Series alkali metal Group, Period, Block 1 (IA), 3, s Density, Hardness 968 kg/m3, 0. ...


There are many classes of medications for treating hypertension, together called antihypertensives, which—by varying means—act by lowering blood pressure. Evidence suggests that reduction of the blood pressure by 5-6 mmHg can decrease the risk of stroke by 40%, of coronary heart disease by 15-20%, and reduces the likelihood of dementia, heart failure, and mortality from vascular disease. Antihypertensives are a class of drugs that are used In medicine and pharmacology to treat hypertension. ...


Which type of medication to use initially for hypertension has been the subject of several large studies. The JNC7 (The Seventh Report of the Joint National Committee on Prevention of Detection, Evaluation and Treatment of High Blood Pressure) recommends starting with a thiazide diuretic if single therapy is being initiated and a another medication is not indicated. This is based on a slightly better outcome for chlorothiazide in the ALLHAT study versus other anti-hypertensives and because thiazide diuretics are relatively cheap. Another large study (ANBP2) published after the JNC7 did not show this small difference in outcome and actually showed a slightly better outcome for ACE-inhibitors. The bottom line is this - the fundamental goal of treatment should be blood pressure control and in reality all three classes of medications are very effective.


There is also anecdotal evidence that consumption of cinnamon is very effective in lowering blood pressure. The USDA has three ongoing studies that are monitoring this effect. Binomial name Cinnamomum zeylanicum Blume Cinnamon (Cinnamomum zeylanicum, synonym ) is a small evergreen tree 10-15 m tall, belonging to the family Lauraceae, and a spice obtained from the inner bark of this species. ...


References

  • Chobanian AV et al. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. JAMA 2003;289:2560-72. Fulltext (http://jama.ama-assn.org/cgi/content/full/289.19.2560v1). PMID 12748199.

JAMA is the acronym for the Journal of the American Medical Association, a leading medical journal. ...

External links

  • The Framingham Heart Study (http://www.nhlbi.nih.gov/about/framingham/)
  • Information on ALLHAT (http://allhat.sph.uth.tmc.edu/default.htm#study)
  • A guide to lowering high blood pressure (http://www.nhlbi.nih.gov/hbp/) from the National Heart, Lung, and Blood Institute
  • The DASH diet (http://www.nhlbi.nih.gov/hbp/prevent/h_eating/h_eating.htm) from the National Heart, Lung, and Blood Institute
  • High Blood Pressure (http://www.americanheart.org/presenter.jhtml?identifier=2114) (from the American Heart Association)
  • High Blood Pressure and Kidney Disease (http://kidney.niddk.nih.gov/kudiseases/pubs/hypertension/index.htm) from The National Kidney and Urologic Diseases Information Clearinghouse
  • High Blood Pressure (http://medlineplus.nlm.nih.gov/medlineplus/highbloodpressure.html) from MedlinePlus

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