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Causes and risks of high blood pressure

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Updated on February 23, 2021

What is blood pressure?

To understand blood pressure, it’s helpful to remember a bit about the circulatory system. With every beat, the heart transports oxygen-rich blood through the body to tissues and organs that need it to function. Blood pressure is set by the volume of blood the heart pumps and the level of resistance it encounters against the arterial walls. The more blood pumped and the narrower the arteries, the higher the pressure.

Blood pressure naturally increases and decreases throughout each day depending on your level of activity. High blood pressure, also called hypertension, is a common condition where the force of blood against the arterial walls is consistently too high.

What is considered high blood pressure?

A blood pressure reading consists of 2 numbers, measured in millimeters of mercury (mm Hg).

  • The first, or top, number measures the systolic pressure in your arteries when your heart beats.
  • The second, or bottom, number measures the diastolic pressure in your arteries when the heart rests between beats.

According to a 2017 guideline from The American College of Cardiology/American Heart Association, normal blood pressure is less than 120/80 mmHg. Anything over that, in either systolic or diastolic pressure, is considered high.

What are the symptoms of high blood pressure?

High blood pressure is a “silent killer” because it usually presents no warning signs. Most people are unaware they have it, even at dangerously high levels. High blood pressure damages the body for years before the onset of symptoms.

Some people may have headaches, shortness of breath or nosebleeds. But these symptoms aren’t necessarily specific to hypertension. Measuring your blood pressure is the only way to get an accurate diagnosis.

What causes high blood pressure?

Two types of hypertension exist: primary and secondary. Primary hypertension develops progressively over time, with no singular identifiable cause. Secondary hypertension results from an underlying condition or a medication’s side effect and appears suddenly and severely.

Secondary hypertension may be a symptom of:

  • Diabetes
  • Obstructive sleep apnea
  • Kidney disease
  • Adrenal gland tumors or thyroid problems
  • Congenital blood vessel defects
  • Obesity
  • Pregnancy
  • Stress

High blood pressure may also be caused by medications such as birth control pills, cold remedies, over-the-counter pain relievers, and other prescription drugs. It can also be caused by illegal drugs like cocaine and amphetamines.

Unhealthy lifestyle choices also contribute to high blood pressure. These include:

1. Not being physically active.

Inactive people usually have a higher heart rate. The faster the heartbeat, the harder the heart works and the stronger the force on the arteries. Physical inactivity also increases the risk of being overweight. The more you weigh, the more blood is needed to provide oxygen to organs and tissues. The more blood flowing through the arteries, the higher the pressure.

2. Using tobacco.

Smoking and chewing tobacco immediately increase blood pressure, and the chemicals in tobacco damage the lining of your arteries. This narrows the arteries and increases the risk of heart disease. Secondhand smoke has the same effect.

3. Excess sodium in your diet.

Too much salt in your diet causes you to retain water, increasing the volume of blood and raising blood pressure.

4. Not enough potassium in your diet.

Potassium balances the amount of sodium in your body. Losing potassium from dehydration or other health issues or not getting enough through diet causes sodium levels to increase.

5. Alcohol abuse.

Over time, overconsumption of alcohol damages the heart. More than one drink a day for women and two for men may affect blood pressure.

Sometimes, high blood pressure is just a result of biology and genetics.

  • The risk of hypertension increases with age. Until the age of about 65, hypertension is most common in men. Women are more likely to develop high blood pressure after 65.
  • Race can be a factor. Hypertension is prevalent among people of African descent, often developing at an earlier age than in other races. Serious complications, such as strokes, heart attacks and kidney failure, are also more common among people of African ancestry.
  • People with a family history of high blood pressure are more likely to get hypertension themselves.

Children are also at risk for high blood pressure for the same reasons as those listed above.

Dangers of high blood pressure

Over time, excessive pressure on the walls of the arteries causes tears where cholesterol will form plaque deposits. These deposits signify the onset of atherosclerosis, hardening and thickening the arteries and making them less elastic. The greater the damage, the narrower the arteries become, decreasing blood flow to the heart and other organs. This lack of oxygen-rich blood causes complications in multiple systems in the body. Here are some complications of uncontrolled high blood pressure:

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In the circulatory system,

  • Heart failure is a condition where your heart can’t pump enough blood and oxygen to your other organs. An overworked heart’s walls begin to thicken in the pumping chamber (called left ventricular hypertrophy). The thickened muscle weakens and, eventually, the heart begins to fail. Symptoms such as angina (chest pain) may appear.
  • A heart attack happens when the heart’s blood supply is blocked, and the muscle begins to die without enough oxygen. The longer the blood flow is blocked, the greater the damage.
  • Constant pressure from blood moving through a weakened artery can cause a section of the arterial wall to enlarge and form an aneurysm . Aneurysms can potentially rupture and cause life-threatening internal bleeding.

In the central nervous system,

  • The brain needs a consistent blood supply to work properly. High blood pressure can cause transient ischemic attacks (TIA), sometimes called mini-strokes. These are brief, temporary disruptions of blood to your brain caused by clots or hardened arteries from high blood pressure. TIA is a warning sign you may be at risk for a stroke.
  • A stroke occurs when part of your brain is deprived of oxygen and cells begin to die. Narrow, damaged blood vessels can leak or rupture. This and blood clots lead to a stroke, which causes serious disabilities and can even be fatal.
  • Studies suggest that high blood pressure causes mild cognitive impairment, affecting the ability to think, understand, remember and learn, especially with age.
  • Limited blood flow to the brain may eventually lead to vascular dementia.

In the renal system,

  • Hypertension damages the blood vessels in the kidneys, preventing them from filtering excess fluid and waste properly. This can eventually cause scarring (glomerulosclerosis), which leads to kidney failure. When the kidneys no longer function and dangerous levels of waste and fluid accumulate, you might need dialysis or a transplant.

In the ocular system,

  • Hypertension may cause retinopathy, which is damage to the retina from high blood pressure injuries to the blood vessels in the eyes. This can lead to bleeding, blurred vision and complete vision loss.
  • High blood pressure may also cause choroidopathy, which is fluid buildup under the retina. This also results in impaired vision from scarring.
  • Blocked blood flow harms the optic nerve (optic neuropathy), leading to bleeding within the eye or vision loss.

In the reproductive system,

  • Men with high blood pressure are more likely to experience erectile dysfunction from reduced blood flow to the penis.
  • Women may also experience sexual dysfunction from high blood pressure.
  • Coming into pregnancy with elevated blood pressure is the single greatest risk factor for the development of preeclampsia. Preeclampsia is a hypertensive condition that can lead to preterm delivery and restricted infant growth, as well as severe maternal complications such as liver and kidney failure, seizure and stroke.

How to lower blood pressure

The best prevention is to make lifestyle changes It is also important to take your blood pressure measurement regularly. Blood pressure can be checked with at-home blood pressure monitors (though speak with your doctor or pharmacist for proper guidance). Here are some practices to help lower blood pressure:

  • Exercising at least 30 minutes a day, 5 days a week.
  • Not smoking
  • Eating a healthy, low-salt diet
  • Maintaining a healthy weight
  • Managing stress
  • Drinking alcohol only in moderation

If positive lifestyle changes are not enough, many blood pressure medications can help relieve hypertension. By being proactive, knowing your risk factors, checking your numbers and staying healthy, you can protect yourself against heart disease, stroke and other complications of hypertension.