Hypertension (high blood pressure)

DESCRIPTION

Introduction

Hypertension is a condition in which the blood vessels have persistently raised pressure.

Blood pressure is one of the vital signs of life. It is the pressure exerted by the blood against the walls of your blood vessels. In hypertension, the blood exerts increased pressure on the walls of the vessels. Therefore, it is also called high blood pressure. It is measured in millimeters of mercury (mmHg) and expressed as systolic/diastolic blood pressure. ‘Systolic’ is the maximum pressure exerted when your heart contracts to pump blood. ‘Diastolic’ is the minimum pressure exerted when your heart is at rest between contractions.

Some people may have high blood pressure readings when measured at the doctor’s clinic but normal blood pressure readings when measured at home or while performing their routine activities (ambulatory blood pressure). This condition is termed white coat hypertension. In contrast, some people may have normal blood pressure readings when measured at the doctor’s clinic but consistently above normal blood pressure readings when measured at home or while performing their routine activities. This condition is termed masked hypertension.

According to A Global Brief on Hypertension published by the World Health Organization, “Hypertension is defined as a systolic blood pressure equal to or above 140 mmHg and/or diastolic blood pressure equal to or above 90 mmHg.”

According to the American Heart Association (AHA) 2017 guidelines, hypertension is defined as systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥80 mmHg.

Types:

There are two main types of hypertension:

1. Essential hypertension - It is the type of high blood pressure which has no obvious underlying medical condition. It has three subtypes:

Systolic hypertension in teenagers and young adults - It occurs mainly in people aged between 17-25 yrs of age. Its prevalence varies and may reach up to 25% in young men. There is an underlying sympathetic system overactivity.

Diastolic hypertension in middle age - It is a condition in which both the systolic and the diastolic blood pressures are elevated. It mostly occurs in patients between 30-50 yrs of age and is associated with weight gain.

Isolated systolic hypertension in older adults - It is a condition in which the systolic blood pressure is increased and the diastolic blood pressure is normal or lower. Therefore, the difference between the systolic BP and diastolic BP is increased. It is often seen in older people with hypertension.

2. Secondary hypertension - This type of high blood pressure is caused as a result of some underlying medical conditions of the kidneys, heart, blood vessels, or endocrine (hormonal) system. Some of the common causes are renal parenchymal disease, acute/chronic renal diseases, renovascular hypertension, endocrinal causes like pheochromocytoma, acromegaly, hypothyroidism, hyperparathyroidism, etc. and coarctation of aorta, especially in young people with high blood pressure.

Further, based on fluctuations in blood pressure within your arteries, you may also be classified as one among the following types:

1. Labile hypertension: Some elderly patients undergo frequent changes in blood pressure over a short-term duration. Conventional medication is unable to stabilize the blood pressure in such patients.

2. Malignant hypertension: This is the most severe form of hypertension in which a very high blood pressure develops suddenly and quickly. This is a medical emergency. The diastolic blood pressure often rises above 130 mmHg and is accompanied by bleeding in the retina. Also, there is leaking of lipid residues from damaged retinal capillaries (called as exudates) with a swelling of optic disc (called as papilledema). Optic disc is the place where the nerve that goes to your brain is connected inside your eyes.

3. Accelerated hypertension: This type is identified by the presence of high blood pressure accompanied by retinal bleeding and/or exudates but without optic disc swelling.

Severe rise in BP (>180/120 mmHg), accompanied with organ damage like hypertensive encephalopathy, acute ischemic stroke, acute MI, etc. is termed as hypertensive emergency. If the severe elevations in BP are not associated with progressive organ dysfunction then the situation is termed as hypertensive urgency. Majority of such situations arise due to inadequate treatment of hypertension or if the person fails or refuses to take medications as prescribed (non-compliance).

Scientific synonyms

HTN/HT
Arterial hypertension

Non-scientific synonyms

Increased blood pressure
Elevated blood pressure
High blood pressure

Disease type

Chronic

Onset age

Neonatal hypertension - hypertension present at birth - (prevalence of 0.2-3%)

Children and adolescents

Adults

The risk of high blood pressure increases with age. It is very common in people who are above the age of 40.

Organ Involved

Circulatory system (heart and blood vessels)

Sex

When compared to women of the same age group, men younger than 65 have consistently higher levels of hypertension. The difference in prevalence of hypertension, with regard to gender, is particularly evident in early adulthood. However, both men and women are at equal risk of hypertension after the age of 65.

The main reason behind different observations in men and women is due to biological and behavioral factors. The biological factors are sex hormones, chromosomal differences, and other biological sex differences. These biological factors show up during adolescence and persist through adulthood until menopause and are protective against hypertension in women. Behavioral risk factors include high body mass index (BMI) and, to a lesser extent, smoking and low physical activity.

Causes/Transmission

Kidney disease
Hormone conditions
Obesity
Drug-induced
Unknown

The cause for hypertension is unknown in majority of the cases. The interplay of genetic, environmental, behavioral and dietary factors is responsible for the development of hypertension. In some cases, it is due to an underlying, potentially correctable cause like kidney disease, hormone conditions, obesity, certain medications, etc.

Risk Factors

Modifiable

Current cigarette smoking, secondhand smoking
Diabetes mellitus
Dyslipidemia/hypercholesterolemia
Overweight/obesity
Physical inactivity/low fitness
Unhealthy diet
Harmful use of alcohol

Non-Modifiable (relatively fixed risk factors)

CKD
Family history
Increased age
Low socio-economic/educational status
Globalization, urbanization
Gender (more prevalent in males)
Obstructive sleep apnea
Psychosocial stress

Factors that contribute to the development of hypertension and its complications are:

Social determinants and drivers: These have an adverse influence on behavioral risk factors and thus, influence the development of hypertension.

Globalization - Globalization influences the labor market. Job insecurity, downsizing/restructuring, unemployment, long work hours, etc. may increase the stress levels which in turn influences hypertension.

Urbanization - Rapid and unplanned urbanization has resulted in unhealthy environments. This has also encouraged sedentary lifestyle, regular use of fast food, and addiction to tobacco and alcohol, etc. All these lifestyle changes have in turn promoted the development of hypertension in an otherwise healthy individual.

Aging - Your blood vessels get stiffened as you add years in age. These stiff blood vessels increase your risk of hypertension.

Income - Studies suggest that low wages are risk factors for hypertension, especially for women and persons aged 25–44 years.

Education - Education makes people aware and influences people to improve their lifestyle and dietary habits. Educated people are more concerned and alert about adopting healthy habits. Lower the level of education, higher the risk of increased blood pressure.

Housing - Lack of access to diagnostics and treatment due to the area people are living in can delay timely detection and treatment. It may also hinder the prevention of complications.

Behavioral risk factors: Highly influenced by people’s living and working conditions

Unhealthy diet
Tobacco use
Physical inactivity
Harmful use of alcohol

Metabolic risk factors

Obesity
Diabetes
Raised blood lipids

Other factors

Genetics
Kidney disease
Endocrine disease
Malformations of blood vessels

Symptoms

Headache
Dyspnea
Dizziness
Nosebleeds
Changes in vision
Chest pain
Fatigue

Signs

Swelling in the legs and feet
Abnormal heart sounds
Narrowing of the eye blood vessels
Retinal bleeding
Changes in reflexes

Hypertension is a ‘silent killer’. Most of the time, the signs and symptoms are none. Symptoms may show up in long-standing or severe hypertension.

Headache - You may experience headache only in severe cases. You may feel pain just as you wake up in the morning. Most commonly this pain is felt on the lowest back side of the head (called as an occipital region) and is throbbing in nature.

Breathlessness - With time, hypertension can cause thickening of your heart wall which can eventually lead to shortness of breath. Breathlessness is a prime symptom of pulmonary hypertension (high blood pressure in the blood vessel network connecting the heart and lungs).

Dizziness - Studies have shown a significant association between dizziness and hypertension in the elderly population. Dizziness could be due to impaired blood flow to the brain.

Nosebleeds - Your nose may bleed as a consequence of your long-lasting hypertension.

Changes in vision- Hypertension causes generalized narrowing of small vessels of the retina. Continued high blood pressure results into insufficient blood flow to the retina. Persistent high blood pressure can also lead to the breakdown of the blood-retina barrier, thereby affecting your eyesight.

Investigations

Laboratory tests for:

CVD (cardiovascular disease) risk factor profiling

Screening secondary causes of hypertension

Basic testing:

Fasting blood glucose
Complete blood count
Lipid profile
Serum creatinine with eGFR
Serum sodium, potassium, calcium
Thyroid-stimulating hormone
Urinalysis
Electrocardiogram

Optional testing:

Echocardiogram
Uric acid
Urinary albumin to creatinine ratio

You will be evaluated through your medical history, physical examination, routine laboratory tests, and certain diagnostic procedures. Your doctor will identify the signs and symptoms that may be due to high blood pressure. The clinical findings may help uncover an underlying health disorder too.

Diagnosis of hypertension is based on blood pressure measurements. According to WHO, the measurements need to be recorded for several days before a diagnosis of hypertension can be made. Two consecutive measurements at least a minute apart are taken and recorded twice daily (morning and evening). First-day measurements are discarded and the average of the remaining measurements is taken to confirm a diagnosis.

One important thing to note is that if a person records high blood pressure at any single occasion, it does not imply that the person is hypertensive. The blood pressure readings are based on an average of more than two careful readings recorded on more than two occasions.

Laboratory tests are done for screening secondary causes of hypertension when the clinical indications and physical examination findings are present. Adults with resistant hypertension are also screened for secondary hypertension. Additional diagnostic tests may include complete blood count, urinalysis, urine culture, BUN, creatinine, electrolytes test, lipid profile, renal ultrasound, etc.

Management

The first and fundamentally important step in the management of hypertension is dietary and lifestyle modification. If your SBP is between 120–129 mmHg your condition is termed elevated blood pressure. You can prevent its progression to Stage 1 and Stage 2 hypertension with non-pharmacological therapies like dietary modifications and lifestyle changes. You may not need any medications. If you have hypertension i.e. your SBP is ≥130 mmHg and DBP is ≥80 mmHg, then you may be able to manage your condition with non-pharmacological therapy alone or you may need medications too.

Dietary

Correct your abnormal dietary habits: Dietary corrections play a very significant role in managing as well as preventing hypertension. A heart-healthy diet like the DASH (Dietary Approaches to Stop Hypertension) diet is recommended. It can help you achieve a desirable weight too. Eat a healthy and balanced diet. Include fresh fruits and vegetables, whole grains, high fiber, etc. Reduce the content of saturated and total fat in your diet. Mediterranean diet may be effective in reducing BP as well as improving your cholesterol levels. The diet emphasizes on consumption of legumes and monounsaturated fat and avoidance of red meats.
You should decrease your salt intake by at least 1000 mg/day. A moderate reduction in salt intake can lead to a small decrease in your blood pressure levels. You may be able to lower your BP by 2-8 mmHg by limiting your daily salt intake to less than 6 g.
Potassium supplementation (3500–5000 mg/day) is recommended for adults with hypertension. But this supplementation should be avoided if you have chronic kidney disease (CKD) or if you are using drugs that reduce potassium excretion.

Lifestyle

Losing weight if you are overweight or obese, and regular physical activity can help you manage high blood pressure. Most adults who are overweight should aim for at least 1 kg reduction in their body weight. Every 1 kg reduction in body weight can help decrease blood pressure by about 1 mmHg.
Increase your physical activity. Aerobic exercise can be an effective way. You can workout for 90–150 min/week. It could help you lower your BP by 5 to 8 mmHg.
Quit smoking, if you smoke. Achieving normal blood pressure ranges can be your ideal motivation to quit smoking.
Stress reduction plays an equally important role in reducing your blood pressure levels.
Reduce your alcohol consumption. Adult men and women with hypertension who currently consume alcohol are advised to reduce their consumption entirely. Men must not drink more than 2 standard drinks/day, whereas women must not drink more than 1 standard drink* per day.
When the above measures fail to control the blood pressure, prescription medications are used. Keep track of your medications. Take them as directed by the doctor. Go for regular check-ups. Monitor your blood pressure levels. Record your BP at regular intervals at home with automatic digital blood pressure monitors. The frequency of medical follow-up will depend on the stage of your hypertension.

Hypertension is a lifelong disease. Hence, it needs to be managed for the rest of your life. You will need to make the necessary dietary and lifestyle changes to efficiently manage your condition. Eating healthy, exercising regularly, reducing weight, limiting alcohol intake, quitting smoking, etc. can go a long way in managing the condition.

Blood Pressure Monitor

The American Heart Association recommends the use of home BP monitoring device to monitor your blood pressure over long periods of time. The device can help you comply with your therapy and achieve good blood pressure control. It can also help your doctor determine whether the treatment is working.

Telehealth services

Telehealth strategies are new and innovative tools that can be useful adjuncts in the management of your hypertension. Use of telemedicine, digital health (‘eHealth’), and mobile computing and communication technologies (‘mHealth’) have been shown to help achieve greater reductions in SBP and DBP. Wireless technologies allow linking of your BP measurement devices to a remote computer or the mobile device of the telehealth provider who can store, analyze and generate reports of your BP recordings.

Treatment

The main aim of treatment of hypertension is to keep the blood pressure within the normal range to lower the risk of future complications. Many drugs like diuretics, calcium channel blockers (CCBs), angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), beta blockers, vasodilators, etc. are currently available for reducing blood pressure. More than two-thirds of hypertensive individuals are suggested two or more antihypertensive drugs, selected from different classes of drugs to treat their hypertension.

Drug therapy

Diuretics
Calcium channel blockers
Angiotensin-converting enzyme (ACE) inhibitors
Angiotensin II receptor blockers (ARBs)
Beta blockers
Vasodilators

The first drugs that you may be prescribed to treat your hypertension (First-line treatment) may include thiazide diuretics, CCBs and ACEI/ARBs. If you have stage 2 hypertension but do not possess any high-risk situation then you may be prescribed two antihypertensive drugs from different classes instead of any specific drug.

1.Diuretics: Diuretics like hydrochlorothiazide eliminate excess salt and water from the body and also decrease calcium excretion. There are different types of diuretics that act at different sites of the renal tubules (small tubes) in the nephrons (functional unit of kidney). A few types of diuretics used in the treatment of hypertension are:

Thiazides – hydrochlorothiazide, chlorthalidone, etc.
Loop diuretics – furosemide, torsemide, etc.
Potassium-sparing diuretics – triamterene, amiloride, etc.

2. Calcium channel blockers bind to calcium channels in the blood vessels and block the entry of calcium. This causes dilatation of the blood vessels which helps decrease blood pressure. Calcium channel blockers are of two types:

Dihydropyridines - amlodipine, nifedipine, clevidipine, etc.
Nondihydropyridines – verapamil, diltiazem, etc.

3. ACE inhibitors inhibit the angiotensin-converting enzyme which regulates salt and water retention in the body. They also lower blood pressure by relaxing the blood vessels, decreasing blood volume and increasing sodium excretion in the urine. A few examples in this class of drugs are fosinopril, captopril, enalapril, ramipril, lisinopril, benazepril, etc.

4. If you are unable to tolerate ACE inhibitors, ARBs are used. They block angiotensin-II (a hormone which causes your blood vessel to constrict) from binding to its receptor and antagonize its action. This helps reduce your blood pressure. Some examples in this class of drugs are losartan, valsartan, irbesartan, fimasartan olmesartan, candesartan, etc.

5. If you are suffering from some serious conditions of the heart like heart failure, myocardial infarction, etc., beta-blockers are the prescribed alternatives. Atenolol, metoprolol, propranolol, oxprenolol, labetalol, etc. are some of the drugs in this class.

6. Vasodilators help lower blood pressure by relaxing the blood vessels’ walls and decreasing their resistance. Hydralazine and minoxidil are vasodilators that work directly on the vessel walls to decrease blood pressure.

Treatment of resistant hypertension

Older age, obesity, chronic kidney disease and diabetes are some of the factors that increase the risk for resistant hypertension. You may have resistant hypertension if you are on 3 antihypertensive medications which when taken together, relieve high blood pressure (complementary mechanisms of action) but are still not able to achieve control over your high blood pressure or if you need ≥4 medications to achieve BP control. Resistant hypertension increases the risk of myocardial infarction, stroke, kidney failure, and death by two to sixfold.

Combinations of medications (calcium channel blockers, inhibitors of renin-angiotensin system (ACE/ARBs), and diuretic chlorthalidone) whose mechanisms of action complement one another can help enhance blood pressure control.
Addition of spironolactone to the multidrug therapy can provide a considerable reduction in blood pressure.
Addition of a vasodilator (hydralazine or minoxidil) can effectively control blood pressure if you are resistant to usual combination therapy.
The underlying medical condition causing your hypertension needs to be corrected and you will also need to improve your adherence to medications.

You may have refractory hypertension if your BP remains uncontrolled despite using at least 5 antihypertensive agents of different classes, including a long-acting thiazide-type diuretic and a mineralocorticoid receptor antagonist. Refractory hypertension has been linked to high rates of cardiovascular complications and stroke.

Prevention

1. Dietary:

Eat a healthy and balanced diet. Include fresh fruits and vegetables, whole grains, high fiber, etc.
Reduce salt intake. Avoid processed food.

2. Lifestyle:

Get involved in some or the other physical activity.
Engage in moderate physical activity for at least 30 minutes every day.
Maintain a healthy weight.
Do not use tobacco.
Limit alcohol use.
Check your blood pressure regularly with a Home BP monitoring device.
Manage your mental stress through relaxing techniques like yoga, meditation, etc.
Prevent and manage other medical conditions, if any.

Complications

Hypertensive encephalopathy is a brief and reversible condition associated with malignant hypertension. It is caused by disorders of the hormone, nerve, kidney or heart, usage of drugs or intoxications. There is a sudden elevation of blood pressure usually preceded by severe headache and followed by convulsions and coma. Normally, the blood flow through your brain is maintained through autoregulatory mechanism despite changes in your blood pressure. But the autoregulation fails at very high blood pressure. The permeability of the blood vessels in your brain increases causing swelling, bleeding and increased pressure. This results in the signs and symptoms of brain dysfunction such as severe headache, vomiting, blurred vision, seizure and coma.

Long-standing hypertension can cause harmful consequences. The thickening of the walls of the blood vessels leads to reduced blood flow to different organs of your body. Hypertension can increase the risk of developing coronary artery disease, heart failure, stroke, aortic aneurysm (bleeding from large blood vessels), nephropathy (kidney damage), retinopathy (vision loss), etc. Many people with hypertension also have other health risk factors like smoking, obesity, high cholesterol and diabetes which increase their odds of complications.

1. Coronary artery disease: The damaged blood vessels of the heart can reduce the efficiency of the heart and also increase its workload. This can cause angina (chest pain) and left ventricular hypertrophy (thickening of heart muscle wall), eventually leading to heart failure.

2. Stroke: Uncontrolled hypertension damages and weakens the small vessels in the brain causing them to rupture and leak. It can also lead to the formation of blood clots in the vessels which blocks the blood flow and potentially cause a stroke.

3. Dementia: Hypertension in midlife is also a major risk factor for dementia. Chronically elevated blood pressure causes thickening of the blood vessel wall, thereby narrowing the tiny blood vessels. Plaque accumulation also leads to narrowing of the larger arteries of the brain. These plaques may rupture and completely block the passage of blood within the blood vessels resulting in the death of tissue in areas of the brain responsible for memory and executive function.

3. Aortic aneurysm/dissection: Hypertension weakens the wall of the blood vessels and over time, may cause it to bulge. This forms an aneurysm (a pouch-like structure) in the blood vessel wall which can be fatal when ruptured.

4. Hypertensive nephropathy/CKD: Damaged small vessels in the kidney reduce its blood supply. This leads to reduced kidney functions and eventually to kidney failure.

5. Hypertensive retinopathy: The retina, choroid, and optic nerve of the eye are affected. Blood vessels in the retina of the eye are narrowed. This impairs the vision and leads to retinopathy and eventually blindness.

These complications can be prevented by controlling the blood pressure and the known risk factors. Reduction of blood pressure to <130/80 mmHg has been shown to reduce heart complications by 25%.

Early detection of complications through regular check-ups and examinations can help provide prompt treatment.

Blood vessels – changes that occur in vessels can be detected by determining the ankle-brachial index, the pulse wave velocity, and by pulse wave analysis. Narrowing of blood vessels or accumulation of plaques in the blood vessels can be identified with ultrasound.
Eye – identify early changes in the finer blood vessels of retina by imaging techniques like direct ophthalmoscopy, photography or angiography.
Brain -- Signs of hypertensive retinopathy can help assess stroke risk.
Heart – echocardiography, electrocardiography or MRI can assess left ventricular hypertrophy (LVH) which is a predictor of cardiovascular disease complications.
Kidney – Urinalysis and renal function test can help assess kidney function.

Who can diagnose?

General practitioner,
Physician
Cardiologist

Fact box

Hypertension does not only affect the elderly. According to WHO, in 2015 the prevalence of hypertension in females aged 18 and over was around 20% and males around 24%. The prevalence of hypertension in children and adolescents is 3.5%. The increasing prevalence can be because of the increase in childhood obesity.
Most patients have no obvious symptoms and hence, do not even know that they have hypertension.
There is a steep rise in pulse pressure (difference between the systolic and diastolic blood pressure) with aging. This is because the systolic blood pressure increases continuously between the ages of 30 and 84 years or over, while the diastolic blood pressure increases until 50 years of age. From the age of 60, the diastolic blood pressure slowly starts decreasing and reaches the least at 84 years of age. Hence, isolated systolic hypertension, in which the systolic pressure is elevated but not the diastolic pressure. This condition is most prevalent in people above 50 years of age.
Worldwide, 9.4 million deaths are related to complications of hypertension every year. At least 45% of deaths related to hypertension are due to heart disease, and 51% of deaths due to stroke.
Secondary hypertension is more common in children than in adults.

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