Hypertension

Hypertension or high blood pressure is a medical condition where the blood pressure is consistently elevated. While it is formally called arterial hypertension, the term "hypertension" usually refers to arterial hypertension.

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Persistent hypertension is a risk factor for strokes, heart attacks, heart failure, arterial aneurysm, and is a leading cause of chronic renal failure.

Definition

Blood pressure is a continuously distributed variable and the risk of associated cardiovascular disease also rises continuously. The point at which blood pressure is defined as hypertension is somewhat arbitrary. Currently, sustained blood pressure of 140/90 mmHg or above, measured on both arms, is generally considered diagnostic. Because blood pressure readings in many individuals are highly variable, 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) has defined blood pressure 120/80 mmHg to 139/89 mmHg as "prehypertension." Prehypertension is not a disease category; rather, it is a designation chosen to identify individuals at high risk of developing hypertension.

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. Even lower numbers are considered diagnostic using home blood pressure monitoring devices.

Etiology

Age: Over time, the number of collagen fibers in artery and arteriole walls increases, making blood vessels stiffer. With the reduced elasticity comes a smaller cross-sectional area in systole, and a raised mean arterial blood pressure. High salt intake Sedentary lifestyle Tobacco smoking Alcoholism High levels of saturated fat in the diet Obesity: In obese subjects, losing a kilogram of mass generally reduces blood pressure by 2 mmHg. Stress Low birth weight Diabetes mellitus Various genetic causes Occupational, aircraft and roadway noise exposure.

Pathophysiology

The mechanisms behind the factors associated with inessential hypertension are generally fully understood and are outlined at secondary hypertension. 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

Differentiating between primary and secondary hypertension

Once hypertension has been diagnosed, it is essential to rule out or identify reversible causes. Over 90% of hypertension in adults has no discernible cause and is therefore referred to as "'essential/primary hypertension"'. Frequently, it is a component of the metabolic "syndrome X" in patients with insulin resistance: it co-occurs with type 2 diabetes, combined hyperlipidemia, and central obesity.

• The majority of hypertensive children are affected by secondary hypertension, and the cause should be diligently investigated.

Blood tests are commonly administered to newly diagnosed hypertensive patients.

• "Creatine" (renal function)
• Electrolytes (sodium, potassium)
• Glucose (to identify diabetes mellitus)
• "'Cholesterol"'

Epidemiology

Throughout years of epidemiological research, the level of blood pressure deemed harmful has been revised downward. The Framingham Heart Study conducted in an American city, Framingham, Massachusetts, is a widely-cited and significant series of such studies. Widespread use has been made of both the Framingham and Busselton, Western Australia findings. Insofar as people are similar, this seems reasonable, but it is known that the most effective drugs for specific subpopulations have genetic variations. Recently (2004), it was determined that the Framingham figures significantly overestimate the risks for the UK population. The causes are obscure. Despite this, the Framingham work has been an integral component of British health policy.

Therapy

Lifestyle modification

As the initial treatment for mild to moderate hypertension, doctors recommend weight loss and regular exercise. These steps are highly effective at lowering blood pressure, but they are easier to recommend than to implement, and the majority of patients with moderate or severe hypertension require indefinite drug therapy to achieve a safe blood pressure level. Quitting smoking does not directly lower blood pressure, but it is crucial for people with hypertension because it reduces the risk of many dangerous hypertension-related outcomes, including stroke and heart attack.

Typically, mild hypertension is treated with diet, exercise, and increased physical fitness. A diet rich in fruits and vegetables, fat-free dairy products, and low in fat and sodium reduces hypertensive individuals' blood pressure. Some people develop hypertension as a result of dietary salt, and a third of people experience a reduction in blood pressure as a result of a reduction in salt consumption. Regular light exercise increases blood flow and lowers blood pressure.

DASH Diet

Diet influences the development of hypertension or high blood pressure (the health term). Recently, two studies demonstrated that adhering to a particular diet — the DASH diet — and reducing sodium intake reduces blood pressure.

While each step individually reduces body-fluid pressure, the combination of the eating plan and a reduced sodium intake provides the greatest benefit and may help prevent the development of high body-fluid pressure.

The DASH Diet aims to reduce sodium intake to approximately 1,500 milligrams per day. Those with high blood pressure may benefit most from following this eating plan and reducing sodium intake. However, the mixture is a heart-healthy recipe that can be followed by all adults.

Reducing environmental stressors such as high sound levels and over-illumination is an additional way to treat hypertension.

Medications

"See main article: antihypertensive medications"

There are numerous antihypertensive medication classes for the treatment of hypertension that, by a variety of mechanisms, lower blood pressure. Evidence suggests that lowering blood pressure by 5-6 mmHg can reduce the risk of stroke by 40 percent, the risk of coronary heart disease by 15 to 20 percent, and the likelihood of dementia, heart failure, and vascular disease-related mortality.

Several extensive studies have examined the optimal initial medication for hypertension treatment. 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. A subsequent, smaller study (ANBP2), published after the JNC7, did not find this small difference in outcome and actually found that ACE-inhibitors produced a slightly better outcome in older male patients.

Although thiazides are inexpensive, effective, and recommended by many experts as the best first-line drug for hypertension, they are prescribed less frequently than some newer drugs. This is presumably due to the fact that they are off-patent and therefore rarely promoted by the pharmaceutical industry.

If there is a compelling reason to do so, physicians may initially prescribe antihypertensive drugs that do not contain thiazides. ACE-inhibitors have been shown to lower blood pressure and slow the progression of diabetic nephropathy in diabetic patients with evidence of kidney disease.

Common antihypertensive medications

Examples of common drugs include:

• Beta-blockers including metoprolol (Lopressor®), atenolol, labetalol, and 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, such as chlortalidone and hydrochlorothiazide (also called HCTZ)
• Combination items (which usually contain HCTZ and one other drug)
• Alpha blockers such as terazosin and prazosin include terazosin and prazosin.

The goal of treatment should be to control blood pressure (140/90 mmHg for the majority of patients, and lower in certain circumstances, such as diabetes or kidney disease). Each additional drug may reduce systolic blood pressure by 5-10 mmHg; therefore, multiple drugs are frequently required to control blood pressure.

See also

• Edible salt
• Hypertensive emergency
• Malignant hypertension
• Exercise hypertension
• White coat hypertension

Hypertension Resources
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