Hypertension

Hypertension is abnormally high blood pressure in the arteries, which are the blood vessels that carry blood from the heart to the rest of the body. As the heart beats, it forces blood through the arteries to deliver nutrients and oxygen to the rest of the body. The strength of the blood pushing against the artery walls is blood pressure, which is measured in units called millimeters of mercury (mmHg). The top number in a blood pressure reading is the pressure when the heart pumps (systolic blood pressure), and the bottom number is the pressure between heart beats (diastolic blood pressure).

High blood pressure is a common condition in which the long-term force of the blood against your artery walls is high enough that it may eventually cause health problems, such as heart disease.

Blood pressure is determined both by the amount of blood your heart pumps and the amount of resistance to blood flow in your arteries. The more blood your heart pumps and the narrower your arteries, the higher your blood pressure.

Normal blood pressure is 120 over 80 mm of mercury (mmHg), but hypertension is higher than 130 over 80 mmHg, according to guidelines issued by the American Heart Association (AHA) in November 2017.

You can have high blood pressure (hypertension) for years without any symptoms. Even without symptoms, damage to blood vessels and your heart continues and can be detected. Uncontrolled high blood pressure increases your risk of serious health problems, including heart attack and stroke.

High blood pressure generally develops over many years, and it affects nearly everyone eventually. Fortunately, high blood pressure can be easily detected. And once you know you have high blood pressure, you can work with your doctor to control it.

Symptoms

• Most people with high blood pressure have no signs or symptoms, even if blood pressure readings reach dangerously high levels.
• A few people with high blood pressure may have headaches, shortness of breath or nosebleeds, but these signs and symptoms aren't specific and usually don't occur until high blood pressure has reached a severe or life-threatening stage.

Causes

There are two types of high blood pressure.

• Primary (essential) hypertension - About 95% cases
  • For most adults, there's no identifiable cause of high blood pressure. This type of high blood pressure, called primary (essential) hypertension, tends to develop gradually over many years.
• Secondary hypertension
  • Some people have high blood pressure caused by an underlying condition. This type of high blood pressure, called secondary hypertension, tends to appear suddenly and cause higher blood pressure than does primary hypertension. Various conditions and medications can lead to secondary hypertension, including:
    • Obstructive sleep apnea
    • Kidney problems (chronic kidney disease - CKD is most common)
    • Adrenal gland tumors
    • Thyroid problems
    • Certain defects you're born with (congenital) in blood vessels
    • Certain medications, such as birth control pills, cold remedies, decongestants, over-the-counter pain relievers and some prescription drugs
    • Illegal drugs, such as cocaine and amphetamines

Hypertension is a key feature of some rare genetic disorders, including familial hyperaldosteronism, pseudohypoaldosteronism type 2, Liddle syndrome, Bartter syndrome, Gitelman syndrome, and tumors known as paragangliomas.

Risk factors including:

• Age. The risk of high blood pressure increases as you age. Until about age 64, high blood pressure is more common in men. Women are more likely to develop high blood pressure after age 65.
• Race. High blood pressure is particularly common among people of African heritage, often developing at an earlier age than it does in whites. Serious complications, such as stroke, heart attack and kidney failure, also are more common in people of African heritage.
• Family history. High blood pressure tends to run in families.
• Being overweight or obese. The more you weigh the more blood you need to supply oxygen and nutrients to your tissues. As the volume of blood circulated through your blood vessels increases, so does the pressure on your artery walls.
• Not being physically active. People who are inactive tend to have higher heart rates. The higher your heart rate, the harder your heart must work with each contraction and the stronger the force on your arteries. Lack of physical activity also increases the risk of being overweight.
• Using tobacco. Not only does smoking or chewing tobacco immediately raise your blood pressure temporarily, but the chemicals in tobacco can damage the lining of your artery walls. This can cause your arteries to narrow and increase your risk of heart disease. Secondhand smoke also can increase your heart disease risk.
• Too much salt (sodium) in your diet. Too much sodium in your diet can cause your body to retain fluid, which increases blood pressure.
• Too little potassium in your diet. Potassium helps balance the amount of sodium in your cells. If you don't get enough potassium in your diet or retain enough potassium, you may accumulate too much sodium in your blood.
• Drinking too much alcohol. Over time, heavy drinking can damage your heart. Having more than one drink a day for women and more than two drinks a day for men may affect your blood pressure.
** If you drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and two drinks a day for men. One drink equals 12 ounces of beer, 5 ounces of wine or 1.5 ounces of 80-proof liquor.
• Stress. High levels of stress can lead to a temporary increase in blood pressure. If you try to relax by eating more, using tobacco or drinking alcohol, you may only increase problems with high blood pressure.
• Certain chronic conditions. Certain chronic conditions also may increase your risk of high blood pressure, such as kidney disease, diabetes and sleep apnea.
• Sometimes pregnancy contributes to high blood pressure, as well.
• Although high blood pressure is most common in adults, children may be at risk, too. For some children, high blood pressure is caused by problems with the kidneys or heart. But for a growing number of kids, poor lifestyle habits, such as an unhealthy diet, obesity and lack of exercise, contribute to high blood pressure.

Complications

The excessive pressure on your artery walls caused by high blood pressure can damage your blood vessels, as well as organs in your body. The higher your blood pressure and the longer it goes uncontrolled, the greater the damage.

Long-term hypertension can cause complications through atherosclerosis, where the formation of plaque results in the narrowing of blood vessels. This makes hypertension worse, as the heart must pump harder to deliver blood to the body.

• Uncontrolled high blood pressure can lead to complications including:
  • Heart attack or stroke. High blood pressure can cause hardening and thickening of the arteries (atherosclerosis), which can lead to a heart attack, stroke or other complications.
  • Aneurysm. Increased blood pressure can cause your blood vessels to weaken and bulge, forming an aneurysm. If an aneurysm ruptures, it causes severe bleeding & can be life-threatening.
  • Heart failure. To pump blood against the higher pressure in your vessels, the heart has to work harder. This causes the walls of the heart's pumping chamber to thicken (left ventricular hypertrophy). Eventually, the thickened muscle may have a hard time pumping enough blood to meet your body's needs, which can lead to heart failure.
  • Weakened and narrowed blood vessels in your kidneys. This can prevent these organs from functioning normally & can cause kidney failure.
  • Thickened, narrowed or torn blood vessels in the eyes. This can result in vision loss.
  • Metabolic syndrome. This syndrome is a cluster of disorders of your body's metabolism, including increased waist circumference; high triglycerides; low high-density lipoprotein (HDL) cholesterol, the "good" cholesterol; high blood pressure and high insulin levels. These conditions make you more likely to develop diabetes, heart disease and stroke.
  • Trouble with memory or understanding. Uncontrolled high blood pressure may also affect your ability to think, remember and learn. Trouble with memory or understanding concepts is more common in people with high blood pressure.
  • Dementia. Narrowed or blocked arteries can limit blood flow to the brain, leading to a certain type of dementia (vascular dementia). A stroke that interrupts blood flow to the brain also can cause vascular dementia.

Frequency & Statistics

• According to the World Health Organization (WHO), there’s been a 67% increase in hypertension from 1990 to 2010 in Sub-Saharan Africa, and 40% of all adults are affected. In Africa, 18% of all deaths are related to hypertension, resulting in half a million deaths and 10 million years of lost life in 2010. 
• Hypertension affects an estimated 29 percent of adults in the United States.
• Only about half (54%) of people with high blood pressure have their condition under control.
• Prevalence of the condition increases with age, and approximately 63 percent of people over age 60 are affected.
• In African Americans, the condition is more common, starts at a younger age, and is more severe than in other populations.
• High blood pressure was a primary or contributing cause of death for more than 410,000 Americans in 2014—that’s more than 1,100 deaths each day.
• High blood pressure costs the nation $48.6 billion each year. This total includes the cost of health care services, medications to treat high blood pressure, and missed days of work.

From: American Heart Association - More than 100 million Americans have high blood pressure, AHA says. Published: 31 Jan 2018

• An estimated 103 million U.S. adults have high blood pressure, according to new statistics from the American Heart Association.
• The death rate from high blood pressure increased by nearly 11 percent in the United States between 2005 and 2015, and the actual number of deaths rose by almost 38 percent — up to nearly 79,000 by 2015, according to the statistics. Worldwide, high blood pressure affects nearly a third of the adult population and is the most common cause of cardiovascular disease-related deaths.

From: WHO - Raised blood Pressure

• Worldwide, raised blood pressure is estimated to cause 7.5 million deaths, about 12.8% of the total of all deaths. This accounts for 57 million disability adjusted life years (DALYS) or 3.7% of total DALYS.
  • Raised blood pressure is a major risk factor for coronary heart disease and ischemic as well as hemorrhagic stroke. Blood pressure levels have been shown to be positively and continuously related to the risk for stroke and coronary heart disease.
  • Globally, the overall prevalence of raised blood pressure in adults aged 25 and over was around 40% in 2008. The proportion of the world’s population with high blood pressure, or uncontrolled hypertension, fell modestly between 1980 and 2008. However, because of population growth and aging, the number of people with uncontrolled hypertension rose from 600 million in 1980 to nearly 1 billion in 2008.
  • Across the WHO regions, the prevalence of raised blood pressure was highest in Africa, where it was 46% for both sexes combined. Both men and women have high rates of raised blood pressure in the Africa region, with prevalence rates over 40%.

References & Additional Reading

• Mayo Clinic - High blood pressure (hypertension)
• Mayo Clinic - High blood pressure (hypertension), Diagnosis & treatment
• Medical News Today - Everything you need to know about hypertension. By Markus MacGill. Updated 21 Nov 2018
• CDC - High Blood Pressure
• Genetics Home Reference - Hypertension
• CDC High Blood Pressure Fact Sheet
• American Heart Association - More than 100 million Americans have high blood pressure, AHA says. Published: 31 Jan 2018