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What is hypertension?


Most visits to the doctor include a blood pressure reading, whether you're feeling ill or in for a routine checkup. Let's say the nurse puts the cuff around your arm, inflates it and tells you that your reading is 145 over 95. Wonder what that means?

Health professionals use the following scale to categorize blood pressure readings:

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  • Normal = less than 120/80 mm Hg
  • Prehypertension = 120-139/80-89 mm Hg
  • Hypertension = greater than 140/90 mm Hg
  • Stage I Hypertension = 140-159/90-99 mm Hg
  • Stage II Hypertension = 160 or greater/100 or greater mm Hg

Blood pressure is how much force your blood uses as it pumps blood through your body. Readings are broken into two numbers, systolic and diastolic. The systolic number -- 145 in the above example, or the higher number -- represents how strongly your blood flows while your heart is contracting, and the diastolic number -- 95 in the above example, or the lower number -- represents how strongly your blood flows when your heart is relaxed between heartbeats. The higher your blood pressure, the harder your heart is working to pump blood through your body. A person with a blood pressure reading of 145 over 95 has high blood pressure, known as hypertension.

Hypertension is a silent killer and without proper diagnosis and treatment it can damage vital organs including the brain (stroke), kidneys (kidney failure), legs (peripheral artery disease) and eyes (hypertensive retinopathy and blindness). And, of course, the heart.

When blood flows through our arteries at such high pressure over a long period of time it stretches the arterial walls and weakens blood vessels. Weakened blood vessels can rupture, causing strokes and aneurysms. Additionally, blood clots, cholesterol and plaque can become trapped in hardened, scarred arteries leading to tissue damage, heart attacks and strokes.

Symptoms that most of us would associate with illness such as headaches, vision problems, nausea and vomiting don't commonly appear until blood pressure has risen to severely high levels.

Hypertension and Blood Pressure

Blood pressure normally fluctuates throughout the day -- for example blood pressure is lowest at night while you're asleep and gradually climbs throughout the day, peaking in the mid-afternoon. Abnormal fluctuations such as high blood pressure readings at night could be caused by lifestyle factors such as too much stress, too much caffeine or too much tobacco but those fluctuations could also be indicators of uncontrolled high blood pressure, kidney disease, sleep apnea or adrenal gland tumors. Over time, consistently high blood pressure can contribute to atherosclerosis (hardening of the arteries) and heart failure.

Several factors contribute to the risk for developing hypertension. Some we can influence with lifestyle changes, some we cannot:

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  • Smoking
  • Obesity
  • A diet high in fat and salt
  • Inactivity
  • Stress
  • Older age
  • Family history and genetics
  • Race and ethnicity
  • Gender
  • Disease or medical conditions, including chronic kidney disease, adrenal and thyroid disorders, sometimes even in pregnancy, may also cause high blood pressure. This is known as secondary hypertension.

While you can't change your genetics, you can work with what you've got. In a scientific statement published by the American Heart Association, successfully treating hypertension means it first needs to be diagnosed, which can be difficult due to its asymptomatic nature, and then healthy diet and exercise changes and drug treatment should begin -- usually a lifelong lifestyle and drug plan. Drugs to control blood pressure come in different flavors. One type, diuretics, removes extra water and salt from the body). Others, such as beta blockers, ACE inhibitors and nervous system inhibitors, work to relax and widen blood vessels.

Studies show that when you lower your blood pressure you lower your associated risk of myocardial infarction (heart attack) by 20 to 25 percent and your risk of stroke by 35 to 40 percent, according to a report published in the July 2008 issue of Journal of the American Society of Hypertension.