Hypertension, referred to as high blood pressure, is a medical condition in which the blood pressure is chronically elevated. It was previously referred to as nonarterial hypertension but in current usage, the word “hypertension” without a qualifier normally refers to arterial hypertension. Hypertension can be classified either essential (primary) or secondary. Essential hypertension indicates that no specific medical cause can be found to explain a patient’s condition. Secondary hypertension indicates that the high blood pressure is a result of another condition, such as kidney disease or tumours .
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. Hypertension is considered to be present when a person’s systolic blood pressure is consistently 140 mmHg or greater, and/or their diastolic blood pressure is consistently 90 mmHg or greater.
Although no specific medical cause can be determined in essential hypertension, the most common form has several contributing factors. These include salt sensitivity, renin homeostasis, insulin resistance, genetics, and age. Certain medications, especially NSAIDS (Motrin/Ibuprofen) and steroids can cause hypertension. Licorice (Glycyrrhiza glabra) inhibits the 11-hydroxysteroid hydrogenase enzyme (catalyzes the reaction of cortisol to cortison) which allows cortisol to stimulate the Mineralocorticoid Receptor (MR) which will lead to effects similar to hyperaldosteronism, which itself is a cause of hypertension.
Hypertension is one of the most common complex disorders, with genetic heritability averaging 30%. Data supporting this view emerge from animal studies as well as in population studies in humans. Most of these studies support the concept that the inheritance is probably multifactorial or that a number of different genetic defects each have an elevated blood pressure as one of their phenotypic expressions.
Signs and symptoms
Hypertension is usually found incidentally – “case finding” – by healthcare professionals during a routine checkup. The only test for hypertension is a blood pressure measurement. Hypertension in isolation usually produces no symptoms although some people report headaches, fatigue, dizziness, blurred vision, facial flushing, transient insomnia or difficulty sleeping due to feeling hot or flushed, and tinnitus during beginning onset or prior to hypertention diagnosis.
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. Hypertension is often confused with mental tension, stress and anxiety. While chronic anxiety and/or irritability is associated with poor outcomes in people with hypertension, it alone does not cause it. Accelerated hypertension is associated with somnolence, confusion, visual disturbances, and nausea and vomiting .
Diagnosis 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 or strenuous exercise and without any stress. Cuff size is also important. The bladder should encircle and cover two-thirds of the length of the (upper) arm. The patient should be sitting upright in a chair with both feet flat on the floor for a minimum of five minutes prior to taking a reading. 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. The person should inflate the cuff to 200 mmHg and then slowly release the air while palpating the radial pulse. After one minute, the cuff should be reinflated to 30 mmHg higher than the pressure at which the radial pulse was no longer palpable. 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 . 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.
Automated machines are commonly used and reduce the variability in manually collected readings . Routine measurements done in medical offices of patients with known hypertension may incorrectly diagnose 20% of patients with uncontrolled hypertension.
Home blood pressure monitoring can provide a measurement of a person’s blood pressure at different times throughout the day and in different environments, such as at home and at work. Home monitoring may assist in the diagnosis of high or low blood pressure. It may also be used to monitor the effects of medication or lifestyle changes taken to lower or regulate blood pressure levels.
Home monitoring of blood pressure can also assist in the diagnosis of white coat hypertension. The American Heart Association states, “You may have what’s called ‘white coat hypertension’; that means your blood pressure goes up when you’re at the doctor’s office. Monitoring at home will help you measure your true blood pressure and can provide your doctor with a log of blood pressure measurements over time. This is helpful in diagnosing and preventing potential health problems.”
Some home blood pressure monitoring devices also make use of blood pressure charting software. These charting methods provide printouts for the patient’s physician and reminders to take a blood pressure reading. However, a simple and cheap way is simply to manually record values with pen and paper, which can then be inspected by a doctor.
Lifestyle modification (nonpharmacologic treatment)
Weight reduction and regular aerobic exercise (e.g., jogging) are recommended as the first steps in treating mild to moderate hypertension. Regular mild exercise improves blood flow and helps to reduce resting heart rate and blood pressure. 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.
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 is shown effective based on National Institutes of Health sponsored research. 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 and/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 does not produce chronic hypertension.
Relaxation therapy, such as meditation, that reduces environmental stress, reducing 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 .
Unless hypertension is severe, lifestyle changes such as those discussed in the preceding section are strongly recommended before initiation of drug therapy. Adoption of the DASH diet is one example of lifestyle change repeatedly shown to effectively lower mildly-elevated blood pressure. If hypertension is high enough to justify immediate use of medications, lifestyle changes are initiated concomitantly.
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.
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 necessary to achieve blood pressure control.
Commonly used drugs include:
ACE inhibitors such as creatine captopril, enalapril, fosinopril (Monopril), lisinopril (Zestril), quinapril, ramipril (Altace)
Angiotensin II receptor antagonists: eg, telmisartan (Micardis, Pritor), irbesartan (Avapro), losartan (Cozaar), valsartan (Diovan), candesartan (Amias)
Alpha blockers such as doxazosin, prazosin, or terazosin
Beta blockers such as atenolol, labetalol, metoprolol (Lopressor, Toprol-XL), propranolol.
Calcium channel blockers such as nifedipine (Adalat) amlodipine (Norvasc), diltiazem, verapamil
Direct renin inhibitors such as aliskiren (Tekturna)
Diuretics: eg, bendroflumethiazide, chlortalidone, hydrochlorothiazide (also called HCTZ)
Combination products (which usually contain HCTZ and one other drug)