Hypertension is a chronic medical condition in which the blood pressure is elevated. It is also referred to as high blood pressure or shortened to HT, HTN or HPN. The word “hypertension”, by itself, normally refers to systemic, arterial hypertension.
Hypertension can be classified as either essential (primary) or secondary. Essential or primary hypertension means that no medical cause can be found to explain the raised blood pressure. It is common. About 90-95% of hypertension is essential hypertension. Secondary hypertension indicates that the high blood pressure is a result of (i.e., secondary to) another condition, such as kidney disease or tumors (adrenal adenoma or pheochromocytoma).
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. Even moderate elevation of arterial blood pressure leads to shortened life expectancy. At severely high pressures, defined as mean arterial pressures 50% or more above average, a person can expect to live no more than a few years unless appropriately treated.
Beginning at a systolic pressure (which is peak pressure in the arteries, which occurs near the end of the cardiac cycle when the ventricles are contracting) of 115 mmHg and diastolic pressure (which is minimum pressure in the arteries, which occurs near the beginning of the cardiac cycle when the ventricles are filled with blood) of 75 mmHg (commonly written as 115/75 mmHg), cardiovascular disease (CVD) risk doubles for each increment of 20/10 mmHg.
There are many classes of medications for treating hypertension, together called anti-hypertensives which — by varying means — act by lowering blood pressure.
| Classification | Systolic pressure | Diastolic pressure | ||
| mmHg | kPa (kN/m2) | mmHg | kPa (kN/m2) | |
| Normal | 90–119 | 12–15.9 | 60–79 | 8.0–10.5 |
| Prehypertension | 120–139 | 16.0–18.5 | 80–89 | 10.7–11.9 |
| Stage 1 | 140–159 | 18.7–21.2 | 90–99 | 12.0–13.2 |
| Stage 2 | ≥160 | ≥21.3 | ≥100 | ≥13.3 |
| Isolated systolic hypertension |
≥140 | ≥18.7 | <90 | <12.0 |
| Source: American Heart Association (2003). | ||||
Management
The process of managing hypertension according the guidelines of the British Hypertension Society suggest that non-pharmacological options should be explored in all patients who are hypertensive or pre-hypertensive. These measures include;
- Weight reduction and regular aerobic exercise (e.g., walking) are recommended as the first steps in treating mild to moderate hypertension. Regular exercise improves blood flow and helps to reduce resting heart rate and blood pressure.Several studies indicate that low intensity exercise may be more effective in lowering blood pressure than higher intensity exercise. These steps are highly effective in reducing blood pressure, although drug therapy is still necessary for many patients with moderate or severe hypertension to bring their blood pressure down to a safe level.
- Reducing dietary sugar intake.
- Reducing sodium (salt) in the diet may be effective: It decreases blood pressure in about 33% of people (see above). Many people use a salt substitute to reduce their salt intake.
- Additional dietary changes beneficial to reducing blood pressure includes the DASH diet (dietary approaches to stop hypertension), which is rich in fruits and vegetables and low-fat or fat-free dairy foods. This diet has been shown to be effective based on research sponsored by the National Heart, Lung, and Blood Institute. In addition, an increase in daily calcium intake has the benefit of increasing dietary potassium, which theoretically can offset the effect of sodium and act on the kidney to decrease blood pressure. This has also been shown to be highly effective in reducing blood pressure.
- Discontinuing tobacco use and alcohol consumption has been shown to lower blood pressure. The exact mechanisms are not fully understood, but blood pressure (especially systolic) always transiently increases following alcohol or nicotine consumption. Besides, abstention from cigarette smoking is important for people with hypertension because it reduces the risk of many dangerous outcomes of hypertension, such as stroke and heart attack. Note that coffee drinking (caffeine ingestion) also increases blood pressure transiently but doesnot produce chronic hypertension.
- Reducing stress, for example with relaxation therapy, such as meditation and other mindbody relaxation techniques, by reducing environmental stress such as high sound levels and over-illumination can be an additional method of ameliorating hypertension. Jacobson’s Progressive Muscle Relaxation and biofeedback are also used,particularly, device-guided paced breathing, although meta-analysis suggests it is not effective unless combined with other relaxation techniques.
It is estimated that nearly one billion people are affected by hypertension worldwide, and this figure is predicted to increase to 1.5 billion by 2025.
Medications
There are many classes of medications for treating hypertension, together called anti-hypertensives, 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.
The aim of treatment should be blood pressure control to <140/90 mmHg for most patients, and lower in certain contexts such as diabetes or kidney disease (some medical professionals recommend keeping levels below 120/80 mmHg). Each added drug may reduce the systolic blood pressure by 5–10 mmHg, so often multiple drugs are often necessary to achieve blood pressure control.
Commonly used drugs include the typical groups of:
- ACE inhibitors such as captopril, enalapril, fosinopril (Monopril), lisinopril (Zestril), quinapril, ramipril (Altace)
- Angiotensin II receptor antagonists may be used where ACE inhibitors are not tolerated: eg, telmisartan (Micardis, Pritor), irbesartan (Avapro), losartan (Cozaar), valsartan (Diovan), candesartan (Amias), olmesartan (Benicar, Olmetec)
- Calcium channel blockers such as nifedipine (Adalat) amlodipine (Norvasc), diltiazem, verapamil
- Diuretics: eg, bendroflumethiazide, chlorthalidone, hydrochlorothiazide (also called HCTZ).
Other additionally used groups include:
- Additional diuretics such a furosemide or low-dosages of spironolactone
- Alpha blockers such as prazosin, or terazosin. Doxazosin has been shown to increase risk of heart failure, and to be less effective than a simple diuretic.
- Beta blockers such as atenolol, labetalol, metoprolol (Lopressor, Toprol-XL), propranolol. Whilst once first line agents, now less directly used for this in the United Kingdom due to the risk of diabetes.
- Direct renin inhibitors such as aliskiren (Tekturna).
Finally several agents may be given simultaneously:
- Combination products (which usually contain HCTZ and one other drug). The advantage of fixed combinations resides in the fact that they increase compliance with treatment by reducing the number of pills taken by the patients. A fixed combination of the ACE inhibitor perindopril and the calcium channel blocker amlodipine, recently been proved to be very effective even in patients with additional impaired glucose tolerance and in patients with the metabolic syndrome.