Article

High Blood Pressure (Hypertension): Causes, Symptoms, Treatment, and Prevention
July 05, 201701,105

What is high blood pressure?

When the heart beats it pumps blood. The blood then flows through the arteries, to the rest of the body. As the blood flows through the arteries, it puts pressure on the walls of the arteries. This pressure is called “blood pressure”.1

 

Figure 1: How Blood Flows through the Body

Blood Flow Through the Heart by OpenStax College is licensed under CC 3.0.

There are actually two types of blood pressure1:

Systolic blood pressure: the pressure on the walls of the arteries when the heart is contracting.

Diastolic blood pressure: pressure exerted by the blood on the walls of the arteries when the heart is relaxed

The unit used to measure blood pressure is millimeters of mercury (mm Hg).1

Normal blood pressure values are 120/80 mm Hg, where 120 is the systolic pressure and 80 is the diastolic pressure.

When blood pressure is higher than this, you are said to have “high blood pressure” or “hypertension”.

 

High Blood Pressure Statistics

According to the World Health Organization (WHO), chronic high blood pressure is a leading cause of death worldwide. As of 2015, 20 percent of women and 24 percent of men over the age of 18 had high blood pressure.2

In 2015, Central and Eastern Europe had the highest percentage of men with high blood pressure and Africa had the highest proportion of women with high blood pressure.2

In the past five years, the number of people with high blood pressure has doubled.2

Researchers estimate that, among people with high blood pressure, only 57 percent even know they have it. Around 40 percent are treating their high blood pressure, but only 13.2 actually have it under control.3

 

What are the Stages of High Blood Pressure?

According to the American Society for Hypertension,25 there are three stages of high blood pressure:

  • Prehypertension,
  • Stage 1 high blood pressure and
  • Stage 2 high blood pressure

Which stage your high blood pressure falls under does not depend only on how high your blood pressure is. It is also determined by whether you have markers of heart, artery or organ damage from your high blood pressure or not.4,5

 

Prehypertension5  

You are classified as having prehypertension if:

  • Your systolic blood pressure is between 120 – 139 mm Hg.
  • Your diastolic blood pressure is between 80 – 89 mm Hg.5
  • Your organs do not show signs of damage from your high blood pressure.
  • You do not have heart disease.
  • You may, however, have risk factors for heart disease or signs that you may be on the path to developing heart disease or organ damage, such as:
    • Being obese
    • Having high cholesterol
    • Having high triglycerides
    • Having diabetes
    • Having a sedentary lifestyle
    • Experiencing blood pressure spikes when you are exercising or stressed
    • Seeing spikes in your blood pressure when you eat salty foods
  • Having changes in the size of your heart
  • Having poor relaxation of your arteries when your heart is beating
  • Seeing changes in your kidney function
  • Having changes in how well you see, caused by damage to the blood vessels in the back of your eyes

If your high blood pressure is diagnosed at this stage, treatment may help to prevent your arteries and organs from ever becoming seriously damaged.4

Stage 1 High Blood Pressure

You are classified as having stage 1 high blood pressure if4,12:

  • your systolic blood pressure is between 140–159mm Hg
  • your diastolic blood pressure is between 90–99 mm Hg.
  • you have changes to your heart from your high blood pressure
  • you have signs of damage to your arteries or organs from your high blood pressure

If you do not treat your stage 1 high blood pressure with medications, your organs may become seriously damaged.

Stage 2 High Blood Pressure   

You are considered to have stage 2 high blood pressure if:

  • your systolic blood pressure is over 160 mm Hg
  • your diastolic blood pressure is over 100 mm Hg.12
  • you have any clear signs of heart, artery or organ damage from your high blood pressure. 4

 

Treating stage 2 high blood pressure with medications can help keep damage to your heart, arteries and organs from getting worse.4

 

Causes of High Blood Pressure

Depending on what is causing it, high blood pressure can be classified as either6:

  • Primary high blood pressure or
  • Secondary high blood pressure

Primary High Blood Pressure

High blood pressure which develops slowly and without any apparent cause is called primary high blood pressure.6

It is thought to be caused by combination of factors, such as5:

  • genetic mutations
  • having a large volume of blood
  • changes in how your kidneys handle a hormone called angiotensin
  • unhealthy lifestyle choices (poor diet and/or too little exercise).

Primary high blood pressure is often chronic.

Secondary high blood pressure

Secondary high blood pressure is high blood pressure caused by another disease or condition.6

Causes of secondary high blood pressure include5,6,8:

  • Kidney problems
  • Diabetes
  • Pregnancy
  • Primary aldosteronism (a hormone imbalance that leads to too much sodium in your blood)
  • Adrenal gland tumors
  • Thyroid hyperactivity
  • Sleep apnea
  • Abuse of certain drugs, such as cocaine or amphetamines
  • Alcohol abuse
  • Taking prescription drugs, such as painkillers, decongestants or birth control pills

Unlike primary high blood pressure, secondary high blood pressure usually develops suddenly.6

 

How Does High Blood Pressure Develop from its Risk Factors?

Some of the key players in turning high blood pressure risk factors into high blood pressure include7:

 

Changes in Your Renin-Angiotensin System

The renin-angiotensin system (RAAS) is a complex hormone system involved in keeping your blood pressure normal.

When your blood pressure is too low, a hormone called renin sends signals to your arteries and kidneys. These signals activate two other proteins called angiotensin I and II.

Angiotensin I makes your blood vessels contract, so your blood pressure comes up.

Angiotensin II tells your kidneys stop letting salt get into your urine. This helps keep you from peeing so much, so more water stays in your body. More water in your blood increases the volume of your blood and raises your blood pressure.

If this system becomes unbalanced, it can lead to high blood pressure.7

 

Changes in The Autonomous Nervous System

The autonomous nervous system is in charge of controlling all the things your body does that you don’t need to think about. It controls your breathing, heartbeat, digestion and body temperature.26

It also plays an important role in keeping your blood pressure normal.7

Imbalances in your autonomic nervous system can lead to high blood pressure.

 

Artery Dysfunction

The walls of your arteries are supposed to relax when your heart beats. This makes the space inside your artery bigger, so more blood can flow through more easily and put less pressure on your artery walls.7

If your artery walls stop relaxing the way they should, you can develop high blood pressure. 7

 

Genetics

Genes play a role in high blood pressure. Researchers know this because of studies that show people who have parents with high blood pressure are more likely to get it themselves.

There is no single gene that is able to cause high blood pressure, though. Researchers think that a mixture of several gene mutations leads to high blood pressure.7

 

Symptoms and Complications of High Blood Pressure

Symptoms of High Blood Pressure

Common signs and symptoms of high blood pressure include4,6:

  • trouble breathing
  • headaches
  • fatigue
  • nose bleeds
  • dizziness
  • red cheeks
  • chest pains
  • trouble seeing
  • blood in your urine

Many people with high blood pressure have no symptoms at all until their blood pressure gets very high. Some people never have any symptoms of high blood pressure, no matter how long they have it or how high their blood pressure gets.4,6

Complications of High Blood Pressure9, 10

High blood pressure can cause serious complications including 27:

  • Bulges in the walls of the arteries (aneurysms)
  • Trouble seeing or blindness
  • Changes in the mood, thinking and concentration
  • Kidney damage
  • Heart disease
  • Stroke
  • Preeclampsia (in pregnant women)

 

Aneurysms

Aneurysms are bulges in the wall of an artery. Aneurysms may not cause any symptoms at first, but if they grow large enough, they can press on nearby organs or keep blood from flowing normally.

They can also rupture, which is a medical emergency.9

 

Trouble seeing or blindness

When blood vessels supplying the eye burst or bleed due to excessive blood pressure, it can damage the back of your eye. Damage to the back of your eye can impair your vision or make you go blind.9

 

Figure 2: Complications of High Blood Pressure

Main Complications of Persistent High Blood Pressure by Mikael Häggström is in the public domain.

 

 

Changes mood, thinking and concentration

Long term high blood pressure can lead to changes in the brain. This can cause symptoms such as memory loss, difficulty finding words, trouble focusing or changes in mood.9

Kidney damage

Changes is the arteries running to the kidneys as a result of high blood pressure can decrease the amount of blood the kidneys receive. This can lead to kidney failure.9

Changes in heart function

High blood pressure caused damage to the arteries that supply your heart muscle with blood can decrease blood flow to your heart.  This can cause heart failure or a heart attacks.

Heart failure occurs when the muscles of your heart cannot contract hard enough to pump blood to the rest of your body normally.

A heart attack occurs when so little blood gets to part of your heart muscle that the muscle starts dying.9

Stroke

Damage to the arteries in your brain by high blood pressure can cause a stroke.  A stroke is caused by too little blood reaching areas of your brain, causing the nerve cells there to start dying.9

Preeclampsia

High blood pressure in pregnancy (called gestational high blood pressure) can develop into preeclampsia. This occurs when the mother’s blood pressure raises above 140/90 mm Hg and her kidneys stop functioning normally. Urine tests that find protein in your urine confirm preeclampsia. 27

If left untreated, preeclampsia can develop into eclampsia (seizures or coma), which may be fatal for both mom and baby. 10, 27

 

Diagnosis of high blood pressure8

There are three steps to diagnosing high blood pressure8:

  • Collecting your medical history
  • A physical exam and
  • Testing you for organ damage

 

Medical History

To collect your medical history for high blood pressure diagnosis, your doctor will ask you questions about your health. Usually, these questions include information about:

  • Your blood pressure in the past
  • If you have a family history of high blood pressure
  • Medical conditions that you currently have
  • Your lifestyle: how often you exercise, if you take drugs, etc.
  • Your diet: the foods you typically eat, how much salt you add to your food, types of beverages you usually drink, if you drink alcohol, etc.

 

Physical Exam 

The physical exam to diagnose high blood pressure includes8:

  • Taking your blood pressure (2x on three different days)
  • Measuring of your height, weight and waist circumference
  • Checking your eyes for artery damage
  • Feeling your abdomen to check for masses (tumors) and the health of your kidneys

 

Organ damage tests

To see if any of your organs may be being damaged by high blood pressure, doctors usually order three kinds of tests8:

  • Urine tests
  • Blood tests
  • An ECG (electrocardiogram)

If any of these tests come back positive for signs of, your doctor will likely order additional tests.

 

What is a Hypertensive Crisis?

A hypertensive crisis is a situation where your blood pressure spikes and causes your organs to start shutting down.11

The symptoms of a hypertensive crisis include11:

  • Headache
  • Changes in thinking, mood, concentration and ability to speak
  • Sudden blindness
  • Sudden blurry vision
  • Shortness of breath
  • Chest pain

A hypertensive crisis is dangerous. If you have any of these symptoms, you should seek medical help immediately.

Doctors can give you high blood pressure medications to bring your blood pressure down and stop your organs from shutting down further.11

 

Treatment for High Blood Pressure

Treating high blood pressure involves lifestyle modifications and/or taking high blood pressure medications.

Usually, the goal of treatment is to get your blood pressure under 140/90 mm Hg.

If you have diabetes or kidney disease along with high blood pressure, though, the goal will be to get your blood pressure under 130/80 mm Hg.12

If your high blood pressure was diagnosed early, lifestyle modifications may be enough to get your blood pressure down to these levels.

If you find it difficult to change your diet and lifestyle, or if your high blood pressure was already causing organ damage when it was diagnosed, you may need high blood pressure medications as well.12

 

Lifestyle modifications13

There are several steps you can take at home to help control your high blood pressure. The most important of these include13:

Getting regular exercise

If you have prehypertension or stage 1 high blood pressure, you should start and stick to a regular exercise routine.13

Working out at a moderate intensity for 30 minutes most days of the week can help lower your systolic blood pressure by 4 mm and your diastolic blood pressure by 2.5 mm Hg. 13

If you have stage 2 hypertension, your doctor will likely want you to exercise under medical supervision.13

Reducing your weight   

Every one percent reduction in weight can reduce your systolic blood pressure by 1 mm Hg. Reducing your weight can help you control your high blood pressure.13

Improving your diet

Certain foods can help raise your blood pressure, while others can help lower it. Tweaking your diet to avoid foods that raise your blood pressure and filling your plate with foods that help lower it can help bring your blood pressure down.

Foods that can contribute to high blood pressure include13:

  • Processed foods
  • Fast food
  • Canned soups
  • Salted snacks
  • Fried foods
  • Fatty meats
  • Whole milk dairy products
  • Deli meats
  • Margarine and butter
  • Regular salad dressings

Many of these foods contribute to high blood pressure because they contain a lot of salt. If you have high blood pressure, reducing your salt intake to less than 4 g per day can decrease your systolic blood pressure by 4-5 mm Hg.13

 

Figure 3: Amount of Salt in Common Foods

Salt Levels Can Vary in Common Food Items by the CDC is in the public domain.

 

Filling your plate with artery-healthy foods can further lower your blood pressure. Foods that may help lower blood pressure include13:

  • Fruits
  • Vegetables
  • Lentils
  • Whole grains

 

Limiting your alcohol intake

Drinking too much alcohol can raise your blood pressure.13

If you have high blood pressure, it is a good idea not to drink alcohol too often.

Doctors recommend that

  • men with high blood pressure not drink more than two alcoholic beverages per day
  • women with high blood pressure do not drink more than one alcoholic beverage per day

Both men and women are advised to have least two alcohol free days per week.13

        Quitting smoking

Stopping smoking does not directly lower your blood pressure, but it makes it less likely that your high blood pressure will harm your heart or brain.

If you have high blood pressure and smoke at the same time, you are two to six times more likely to have a heart attack and three times more likely to have a stroke.13

If you would like help quitting smoking, talk to your doctor. There are several strategies available that can help make it easier for you to quit.13

 

High Blood Pressure Medications

In some cases, your doctor may decide that adding a blood pressure medication to your lifestyle modifications is the best option for you.

There are many different kinds of high blood pressure medications, including:

  • Diuretics
  • Beta blockers
  • ACE inhibitors
  • Angiotensin receptor blockers
  • Calcium channel blockers
  • Central acting agents
  • Vasodilators

Which of these types of medications your doctor chooses for you will depend on your medical history and your symptoms.

Diuretics

Diuretics are commonly called ‘water pills’.28

They help your kidneys remove sodium and water from your body. This decreases the volume of your blood, helping lower your blood pressure.

There are two types of diuretics used to treat high blood pressure14:

  • Thiazide diuretics and
  • Potassium sparing diuretics.

Diuretics are often taken along with other high blood pressure drugs.14

Beta blockers

Beta blockers are drugs that decrease how fast and hard your heart pumps. This slows down the speed your blood flows through your arteries, which lowers your blood pressure.

Beta blockers change how your heart beats by stopping your heart from reacting to signals from two hormones: adrenaline and noradrenaline. Adrenaline and noradrenaline normally tell your heart to beat harder and faster.15

While all beta blockers affect your heart, a few beta blockers can also affect your arteries, too. Some beta blockers can stop adrenaline and noradrenaline from telling your blood vessels to get smaller. This keeps your arteries open wide, letting blood flow more easily and lowering your blood pressure.15

Studies suggest the beta blockers that can affect both your heart and arteries might be more effective at lowering blood pressure than beta blockers that just relax your heart.15

ACE inhibitors

ACE (Angiotensin Converting Enzyme) inhibitors work by keeping your arteries from contracting too much.16,17

They do this by stopping your body from making a hormone called angiotensin II.16,17

Angiotensin II tells your blood vessels to contract, so by lowering angiotensin II levels in the body, your arteries contract less.16,17

Angiotensin II receptor blockers

Angiotensin II receptor blockers have the same effect as ACE inhibitors, but work differently.17

Rather than decreasing the amount of angiotensin II in your body, they keep angiotensin II from communicating with your arteries. 17

They do this by blocking the receptor on your artery walls that normally recognizes that angiotensin II is there. 17

Angiotensin II receptor blockers are safer than ACE inhibitors for some people, such as those with kidney disease.17

Calcium channel blockers

Calcium channel blockers help relax both your heart and blood vessels.18

They do this by keeping calcium from flowing into the cells of your heart and the cells lining the walls of your arteries. 18

Calcium flowing into these cells normally causes them to contract, making your heart beat harder and your blood vessels get smaller.18

By blocking the flow of calcium, calcium channel blockers help prevent both of these effects, lowering your blood pressure.18

Central acting agents

Central acting agents lower your blood pressure by changing signals from your brain to your heart and arteries.19

Signals from your brain that normally tell your heart to beat harder and your arteries to contract are blocked by central acting agents. This helps lower your blood pressure. 19

Vasodilators

Vasodilators are drugs that increase the size of your blood vessels. They do this by helping relax the muscles that line the walls of your arteries, opening up more space inside your blood vessels for blood to flow.12

Vasodilators are often taken with diuretics or beta blockers that only affect your heart.12

 

Can You Prevent High Blood Pressure?20

You can prevent high blood pressure from developing by adopting the lifestyle changes that are recommended for people who already have high blood pressure. These include13,20:

  • maintaining a healthy body weight
  • exercising regularly
  • decreasing salt intake
  • eating a healthy diet rich in fruits, vegetables and whole grains
  • drinking alcohol in moderation
  • effectively managing your stress levels

 

High Blood Pressure FAQs

  • What is the most important blood pressure reading: systolic or diastolic blood pressure?

For a long time, doctors thought diastolic blood pressure was the more important blood pressure reading.

New research, however, has shown that systolic blood pressure is also very important.

Doctors now consider systolic and diastolic blood pressure equally important.21

  • What does high blood pressure cause?

High blood pressure can cause22:

  • Damage to your blood vessels (arteries)
  • Heart damage
  • Damage to your brain
  • Kidney damaged
  • Difficulty seeing or complete blindness

 

  • Does stress cause high blood pressure?

Stress can contribute to high blood pressure.23

Stress causes your brain to release a hormone called catecholamine, which increases your heart rate and blood pressure.23

Too much catecholamine in your body, from constant stress, can lead to long term increases in your blood pressure.23

  • Can dizziness be caused by high blood pressure?

High blood pressure can make you dizzy, but only if it is very high. Dizziness is a rare symptom of high blood pressure.24

  • What is the dangerous level of high blood pressure?

Blood pressures over 180/110 mm Hg are considered extremely dangerous. You should seek immediate medical help if your blood pressure is at, above, or near this level.11

References

  1. Hypertension – National Library of Medicine – PubMed Health. https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024199/. Accessed July 10, 2017.
  2. WHO | Raised blood pressure. WHO. http://www.who.int/gho/ncd/risk_factors/blood_pressure_text/en/. Accessed July 12, 2017.
  3. Cayon A. PAHO WHO | World Hypertension Day 2017: Know your numbers. Pan American Health Organization / World Health Organization. http://www.paho.org/hq/index.php?option=com_content&view=article&id=13257%3Adia-mundial-de-la-hipertension-2017-conoce-tus-numeros&catid=9283%3Aworld-hypertension-day&Itemid=42345&lang=en. Accessed July 12, 2017.
  4. Giles TD, Materson BJ, Cohn JN, Kostis JB. Definition and Classification of Hypertension: An Update. J Clin Hypertens. 2009;11(11):611-614. doi:10.1111/j.1751-7176.2009.00179.x.
  5. Weber MA, Schiffrin EL, White WB, et al. Clinical Practice Guidelines for the Management of Hypertension in the Community. J Clin Hypertens. 2014;16(1):14-26. doi:10.1111/jch.12237.
  6. High blood pressure (hypertension) Causes. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/high-blood-pressure/basics/causes/con-20019580.Accessed July 11, 2017.
  7. Beevers G, Lip GYH, O’Brien E. The pathophysiology of hypertension. BMJ. 2001;322(7291):912-916.
  8. Overview of Hypertension – Cardiovascular Disorders. Merck Manuals Professional Edition. http://www.merckmanuals.com/professional/cardiovascular-disorders/hypertension/overview-of-hypertension?sc_camp=cs123. Accessed July 11, 2017.
  9. What Are the Signs, Symptoms, and Complications of High Blood Pressure? – NHLBI, NIH. https://www.nhlbi.nih.gov/health/health-topics/topics/hbp/signs. Accessed July 11, 2017.
  10. Gathiram P, Moodley J. Pre-eclampsia: its pathogenesis and pathophysiolgy. Cardiovasc J Afr. 2016;27(2):71-78. doi:10.5830/CVJA-2016-009.
  11. Varon J, Marik PE. Clinical review: The management of hypertensive crises. Crit Care. 2003;7(5):374-384. doi:10.1186/cc2351.
  12. Nguyen Q, Dominguez J, Nguyen L, Gullapalli N. Hypertension Management: An Update. Am Health Drug Benefits. 2010;3(1):47-56.
  13. The Heart Foundation. lifestyle-modification.pdf. https://www.heartfoundation.org.au/images/uploads/publications/lifestyle-modification.pdf. Accessed July 12, 2017.
  14. Krakoff LR. Diuretics for Hypertension. Circulation. 2005;112(10):e127-e129. doi:10.1161/CIRCULATIONAHA.105.570192.
  15. Ram CVS. Beta-Blockers in Hypertension. Am J Cardiol. 2010;106(12):1819-1825. doi:10.1016/j.amjcard.2010.08.023.
  16. Angiotensin-converting enzyme (ACE) inhibitors. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/ace-inhibitors/art-20047480. Accessed July 12, 2017.
  17. Dézsi CA. Differences in the Clinical Effects of Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers: A Critical Review of the Evidence. Am J Cardiovasc Drugs. 2014;14(3):167-173. doi:10.1007/s40256-013-0058-8.
  18. Delacroix S, Chokka RG, Worthley SG. Hypertension: Pathophysiology and Treatment. J Neurol Neurophysiol. November 2014. doi:10.4172/2155-9562.1000250.
  19. Central-acting agents. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/high-blood-pressure-medication/art-20044451. Accessed July 12, 2017.
  20. WHO | Reducing sodium intake to reduce blood pressure and risk of cardiovascular diseases in adults. WHO. http://www.who.int/elena/titles/sodium_cvd_adults/en/. Accessed July 11, 2017.
  21. Strandberg TE, Pitkala K. What is the most important component of blood pressure: systolic, diastolic or pulse pressure? Curr Opin Nephrol Hypertens. 2003;12(3):293-297. doi:10.1097/01.mnh.0000069868.94246.ef.
  22. High blood pressure dangers: Hypertension’s effects on your body. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/high-blood-pressure/art-20045868. Accessed July 12, 2017.
  23. Spruill TM. Chronic Psychosocial Stress and Hypertension. Curr Hypertens Rep. 2010;12(1):10-16. doi:10.1007/s11906-009-0084-8.
  24. Pubmed Health. High blood pressure: Overview. PubMed Health. July 2015. https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072423/. Accessed July 12, 2017.
  25. Materson B. Diagnostic evaluation. Journal of the American Society of Hypertension. 2014;8(9):680-681. doi:10.1016/j.jash.2014.07.031.
  26. Dysautonomia | Autonomic Nervous System Disorders | MedlinePlus. Medlineplusgov. 2017. Available at: https://medlineplus.gov/autonomicnervoussystemdisorders.html. Accessed September 8, 2017.
  27. Duley L. Pre-eclampsia, eclampsia, and hypertension. BMJ Clinical Evidence. 2008;2008:1402.
  28. Hydrochlorothiazide: MedlinePlus Drug Information. Medlineplusgov. 2017. Available at: https://medlineplus.gov/druginfo/meds/a682571.html. Accessed September 8, 2017.

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