Hypertension
Bold text
Hypertension or high blood pressure is a medical condition wherein the blood pressure is chronically elevated. While it is formally called arterial hypertension, the word "hypertension" without a qualifier usually refers to arterial hypertension.
Persistent hypertension is one of the risk factors for strokes, heart attacks, heart failure and arterial aneurysm, and is a leading cause of chronic renal failure.Blood pressure is a continuously distributed variable and the risk of associated cardiovascular disease likewise rises continuously. The point at which blood pressure is defined as hypertension is therefore somewhat arbitrary. Presently finding sustained blood pressure of 140/90 mmHg or above, measured on both arms is generally regarded as diagnostic. Because blood pressure readings in many individuals are highly variable â€" especially in the office setting â€" the diagnosis of hypertension should be made only after noting a mean elevation on two or more readings on two or more office visits, unless the elevations are severe or associated with compelling indications such as diabetes mellitus, chronic kidney disease, heart failure, post-myocardial infarction, stroke, and high coronary disease risk.
Recently, the JNC 7 (The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure)[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.]Measuring blood pressureDiagnosis of hypertension is generally on the basis of a persistently high blood pressure. Usually this requires three separate measurements at least one week apart. Exceptionally, if the elevation is extreme, or end-organ damage is present then the diagnosis may be applied and treatment commenced immediately.
Obtaining reliable blood pressure measurements relies on following several rules and understanding the many factors that influence blood pressure reading.
For instance, measurements in control of hypertension 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 suitably above anticipated systolic pressure. A stethoscope should be placed lightly over the brachial artery. The cuff should be at the level of the heart and the cuff should be deflated at a rate of 2 to 3 mmHg/s. Systolic pressure is the pressure reading at the onset of the sounds described by Korotkoff (Phase one). Diastolic pressure is then recorded as the pressure at which the sounds disappear (K5) or sometimes the K4 point, where the sound is abruptly muffled. 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. In elderly patients who particularly when treated may show orthostatic hypotension, measuring lying sitting and standing BP may be useful. The BP should at some time have been measured in each arm, and the higher pressure arm preferred for subsequent measurements.
BP varies with time of day, as may the effectiveness of treatment, and archetypes used to record the data should include the time taken. Analysis of this is rare at present.Distinguishing primary vs. secondary hypertensionOnce the diagnosis of hypertension has been made it is important to attempt to exclude or identify reversible (secondary) causes.
* Over 90% of adult hypertension has no clear 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.
* In hypertensive children most cases are secondary hypertension, and the cause should be pursued diligently.Blood tests commonly performed in a newly diagnosed hypertension patient* Creatinine (renal function)
* Electrolytes (sodium, potassium)
* Glucose (to identify diabetes mellitus)
* CholesterolThe 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.Lifestyle modificationDoctors recommend weight loss and regular exercise as the first steps in treating mild to moderate hypertension. These steps are highly effective in reducing blood pressure, but 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. Discontinuing smoking does not directly reduce blood pressure, but is very important for people with hypertension because it reduces the risk of many dangerous outcomes of hypertension, such as stroke and heart attack.
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.
Reduction of environmental stressors such as high sound levels and over-illumination can be an additional method of ameliorating hypertension.MedicationsSee main article: Antihypertensives
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.
Which type of medication to use initially for hypertension has been the subject of several large studies. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) recommends starting with a thiazide diuretic if single therapy is being initiated and another medication is not indicated.[{{cite journal]| url=http://jama.ama-assn.org/cgi/content/full/288/23/2981 | author=ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group | journal=JAMA | title=Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) | year = 2002 | month = Dec 18 | volume = 288 | issue = 23 | pages = 2981-97 | id = PMID 12479763 A subsequent smaller study (ANBP2) published after the JNC7 did not show this small difference in outcome and actually showed a slightly better outcome for ACE-inhibitors in older male patients.[{{cite journal]| url=http://content.nejm.org/cgi/content/abstract/348/7/583 | author=Wing LM, Reid CM, Ryan P et al | journal=NEJM | title=A comparison of outcomes with angiotensin-converting--enzyme inhibitors and diuretics for hypertension in the elderly | year = 2003 | month = Feb 13 | volume = 348 | issue = 7 | pages = 583-92 | id = PMID 12584366
Despite thiazides being cheap, effective, and recommended as the best first-line drug for hypertension by many experts, they are not prescribed as often as some newer drugs. Arguably, this is because they are off-patent and thus rarely promoted by the drug industry.[{{cite journal]| url=http://circ.ahajournals.org/cgi/content/full/99/15/2055 | author=Wang TJ, Ausiello JC, Stafford RS | journal=Circulation | title=Trends in Antihypertensive Drug Advertising, 1985â€"1996 | year = 1999 | volume = 99 | pages = 2055-2057 | id = PMID 10209012
Physicians may start with non-thiazide antihypertensive medications if there is a compelling reason to do so. An example is the use of ACE-inhibitors in diabetic patients who have evidence of kidney disease, as they have been shown to both reduce blood pressure and slow the progression of diabetic nephropathy.[{{cite journal]| url=http://linkinghub.elsevier.com/retrieve/pii/S014067369804433X | author=Ruggenenti P, Perna A, Gherardi G, Gaspari F, Benini R, Remuzzi G. | journal=Lancet | title=Renal function and requirement for dialysis in chronic nephropathy patients on long-term ramipril: REIN follow-up trial. Gruppo Italiano di Studi Epidemiologici in Nefrologia (GISEN). Ramipril Efficacy in Nephropathy. | year = 1998 | volume = 352 | pages = 1252-6 | id = PMID 9788454 In patients with coronary artery disease or a history of a heart attack, beta blockers and ACE-inhibitors both lower blood pressure and protect heart muscle over a lifetime, leading to reduced mortality.
Commonly used drugs include:
*Beta blockers such as metoprolol (Lopressor®), atenolol, labetalol, carvedilol (Coreg®)
*ACE inhibitors such as lisinopril (Zestril®), quinapril, fosinopril (Monopril®), captopril, enalapril, ramipril (Altace®)
*Angiotensin receptor blockers (ARBs): eg, losartan (Cozaar®), valsartan (Diovan®), irbesartan (Avapro®)
*Calcium channel blockers such as amlodipine (Norvasc®), verapamil
*Diuretics: eg, chlortalidone, hydrochlorothiazide (also called HCTZ)
*Combination products (which usually contain HCTZ and one other drug)
*Alpha blockers such as terazosin, prazosin
The aim of treatment should be blood pressure control (<140/90 mmHg for most patients, and lower in certain contexts such as diabetes or kidney disease). Each added drug may reduce the systolic blood pressure by 5-10 mmHg, so often multiple drugs are necessary to achieve blood pressure control.Treatment guidelines need to be updated in accordance with the latest NICE guidelines.* Edible salt
* Hypertensive emergency
* Malignant hypertension
* Exercise hypertension
* White coat hypertension
* Home blood pressure monitoring* The Framingham Heart Study
* Information on ALLHAT
* A guide to lowering high blood pressure from the National Heart, Lung, and Blood Institute
* The DASH diet from the National Heart, Lung, and Blood Institute
* High Blood Pressure (from the American Heart Association)
* High Blood Pressure and Kidney Disease from The National Kidney and Urologic Diseases Information Clearinghouse
* High Blood Pressure from MedlinePlus
* Blood Pressure Monitoring
|
| | | | 
