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What Is Hypertension (HTN)? - Definition, Symptoms & Causes

What Is Hypertension (HTN)? - Definition, Symptoms & Causes
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  • 0:02 Understanding Hypertension
  • 1:37 Stages
  • 2:45 Symptoms
  • 3:48 Primary Hypertension
  • 4:57 Secondary Hypertension
  • 6:51 Lesson Summary
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Lesson Transcript
Instructor: Sheara Williamson

Sheara currently teaches undergraduate biology courses and has her doctorate in Kinesiology.

It is likely that high blood pressure, or hypertension, has affected you or someone close to you. In this lesson, we will define hypertension and get a better understanding of its causes and symptoms.

Understanding Hypertension

Close to one-third of adults have hypertension, or high blood pressure, an all too common cardiovascular disease. As we age, the likelihood that we will develop hypertension increases. Let's quickly review how blood pressure is measured, which will make it easier to understand the categories of blood pressure.

When your blood pressure is read, the systolic pressure represents the pressure in the arteries that is generated when the heart ventricles contract. The diastolic pressure is the pressure in the arteries when the ventricles are relaxing and filling with blood. Pressure is measured in millimeters of mercury, written as mmHg. Normal blood pressure is categorized as less than 120 mmHg systolic pressure and less than 80 mmHg diastolic pressure. Normally, blood pressure will rise and fall as you go through the course of your day, just as your heart rate does.

Hypertension is a condition when your systolic blood pressure is higher than 120 mmHg and your diastolic blood pressure is above 80 mmHg, averaged over time. Sometimes, a patient may have elevated blood pressure in the doctor's office but not at any other time. This is called white coat hypertension and may be credited to a person feeling anxious around doctors in white coats and the sterile environment. In this case, a doctor may prescribe a 24-hour ambulatory monitoring, which you can wear during your normal daily activities. By averaging your blood pressure while you are awake and asleep, a doctor can determine if you are normotensive, an indication of normal blood pressure, or hypertensive.

Stages of Hypertension

If a patient has blood pressure that is consistently above normal, he or she can be further categorized into different stages of hypertension. Here's how doctors classifying blood pressure:

  • Normotensive blood pressure: No risk for hypertension (measured as less than 120 mmHg systolic or less than 80 mmHg diastolic)
  • Prehypertensive blood pressure: At risk for developing hypertension (measured as 120-139 mmHg systolic or 80-89 mmHg diastolic)
  • Stage 1 hypertension: High blood pressure that may be treated with lifestyle changes or medication (measured as 140-159 mmHg systolic or 90-99 mmHg diastolic)
  • Stage 2 hypertension: High blood pressure that may require one or two medications (measured as greater than 160 mmHg systolic or higher than 100 mmHg diastolic). This is the most severe form of hypertension.

In the case of comorbidity, or the presence of another chronic illness like diabetes or renal disease, a doctor may categorize a patient as hypertensive even if they are considered prehypertensive.

Symptoms of Hypertension

You most likely would not know you have hypertension. In most cases, a person will be asymptomatic, having no noticeable symptoms, which is why this disease is so dangerous. If hypertension is not detected, it can wreak havoc on your cardiovascular system by putting excess strain on your blood vessel walls and heart. In some very rare cases, a person may develop a sudden onset of hypertension, which causes noticeable symptoms. Preeclampsia during pregnancy and severe kidney disease are examples. A person experiencing a sudden onset of hypertension may experience any combination of symptoms that range from severe headache, nosebleeds, and nausea to neurological symptoms, like confusion and blurred vision. These symptoms are signs that blood pressure is dangerously high and requires immediate medical attention.

Since hypertension is normally unnoticed, it is important to understand the causes so that you can take measures to reduce the likelihood of developing or decreasing the severity of hypertension.

Primary Hypertension: Causes

Hypertension cannot be attributed to a single cause. It is multifactorial, meaning there are genetic and environmental aspects of the disease. There are two types of hypertension: primary hypertension and secondary hypertension. Primary hypertension does not have a clearly identifiable cause. This type of hypertension rarely has any accompanying symptoms and tends to creep up over the years, which is why it has been deemed a silent killer.

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