10.14: Hypertension
- Page ID
- 100143
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Blood pressure disorders such as hypertension and hypotension affect how well blood moves through the vessels, and understanding them helps explain both long-term health risks and immediate problems with perfusion.
- Distinguish normal, hypertensive, and hypotensive ranges for blood pressure and pulse pressure.
- Explain key causes and health effects of chronic hypertension and hypotension.
- Differentiate primary and secondary hypertension and identify factors that cause inaccurate readings.
Hypertension (high blood pressure) is a chronic condition in which pressure inside the systemic arteries remains elevated over time. When arterial pressure is consistently high, the heart must work harder than normal to push blood through the vessels. You have learned in the previous section that blood pressure is described using two numbers: the systolic pressure, which reflects the force when the ventricles contract, and the diastolic pressure, which reflects the force when the heart relaxes between beats.
Hypertension: A Silent but Serious Condition
Hypertension (high blood pressure) is often called a “silent disorder” because most people do not feel any symptoms, even when their pressure is dangerously high. Hypertension is often called a “silent killer” because most people do not feel any symptoms, even if their pressure is dangerously high. This makes it easy for patients to underestimate the seriousness of the condition or stop following their treatment plan. Often, elevated arterial pressure is an important warning sign of other health problems, and it can cause long-term harm if left untreated.
All blood pressure places some mechanical stress on arterial walls, but higher pressures create far more strain. Over time, this extra stress:
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Increases the workload on the heart
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Promotes the growth of atherosclerotic plaques (atheromas) inside artery walls
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Leads to thickening and enlargement of the heart muscle, which eventually weakens its function
Today we understand that both systolic pressure and pulse pressure (the difference between systolic and diastolic values) are important predictors of cardiovascular risk. While diastolic pressure used to receive most attention, high systolic pressure and wide pulse pressure are now known to be strong indicators of arterial stiffness and disease. In fact, lowering an excessively high diastolic pressure too much may widen the pulse pressure and increase risk. When systolic pressure rises above 140 mmHg but diastolic pressure remains below 90 mmHg, the condition is called isolated systolic hypertension, which is especially common in older adults and still carries significant health concerns.
If hypertension continues untreated, the long-term strain on vessels and the heart can lead to serious, potentially life-threatening complications, such as:
- Heart attack
- Stroke
- Aneurysm (ballooning of a weakened blood vessel wall)
- Peripheral arterial disease (blocked vessels in the limbs)
- Chronic kidney disease
- Heart failure
A normal resting blood pressure typically falls between 100–120 mmHg systolic and 60–80 mmHg diastolic. Hypertension is diagnosed when blood pressure remains at or above 140/90 mmHg on repeated measurements. Chronically elevated pressure can gradually damage vessel walls throughout the body, contribute to arterial disease, strain the heart, and even lead to neurological problems through a stroke.
Primary (or Essential) Hypertension
Hypertension is grouped into two main types: primary (essential) hypertension and secondary hypertension. Primary hypertension makes up about 90 to 95 percent of all cases. In these individuals, blood pressure is high even though there is no single, identifiable medical cause. Most people with primary hypertension have normal cardiac output, but their small arteries and arterioles offer more resistance than normal. This increased resistance is usually due to the gradual narrowing of these vessels, and in some cases a reduced number of capillaries may also contribute.
Secondary Hypertension
Secondary hypertension accounts for the remaining 5 to 10 percent of cases and develops when another health condition raises blood pressure. Kidney disease is the most common cause of secondary hypertension. Other causes include certain endocrine disorders, such hyperthyroidism, hypothyroidism. Secondary hypertension can also result from obesity, sleep apnea, and pregnancy, amongst other conditions.
If high blood pressure is not controlled over time, it can damage blood vessels and organs throughout the body. Chronic hypertension is a major risk factor for heart attack, heart failure, stroke, aneurysms, peripheral arterial disease, and chronic kidney disease. Even moderate, long-term elevation of blood pressure can shorten life expectancy. Healthy lifestyle changes can support blood pressure control and reduce health risks, but many individuals also require medication to keep blood pressure within a safe range.
Not every high BP reading means the patient truly has hypertension. Common errors in measurement and natural fluctuations in blood pressure can result in readings that erroneously suggest hypertension. Blood pressure can appear elevated because of:
- Errors in technique (cuff too small, cuff placed incorrectly, arm not at heart level)
- Operator error
- Client anxiety (“white coat effect”)
- Situational factors such as pain, anxiety, stress, or recent activity, caffeine, smoking, etc.
It is important to distinguish between elevated blood pressure and a diagnosis of hypertension. Elevated blood pressure refers to an isolated reading, whereby the client has an elevated finding. Hypertension is clinical diagnosis whereby the client has met the criteria for chronic elevated blood pressure.
Hypotension: How Low Blood Pressure Differs From High Blood Pressure
When we talk about blood pressure problems, hypertension (high blood pressure) usually gets the most attention. That is because hypertension is extremely common and can silently damage the blood vessels, heart, kidneys, brain, over many years without causing symptoms.
Hypotension, on the other hand, refers to blood pressure that is too low, usually defined as less than 90/60 mmHg. Hypotension is less common than hypertension and often gets less attention, but it can still be important because blood pressure must be high enough to deliver oxygen-rich blood to vital organs such as the brain, heart, and kidneys.
Causes and Concerns of Hypotension
Hypotension can occur for many reasons, including:
- Dehydration
- Bleeding or blood loss
- Heart problems that reduce the amount of blood the heart pumps
- Side effects of medications, such as those used to treat high blood pressure or depression
When blood pressure is too low, the body may not be able to maintain adequate perfusion. Perfusion refers to the delivery of oxygen-rich blood to the tissues and organs of the body. In other words, it is how well blood is flowing through the capillaries to supply cells with the oxygen and nutrients they need. Inadequate perfusion can lead to symptoms such as dizziness, weakness, blurry vision, or even fainting. In severe cases, very low blood pressure can become life-threatening because organs are not receiving enough oxygen.
Orthostatic (Postural) Hypotension
A specific type of low blood pressure is orthostatic hypotension, which happens when someone moves from lying down or sitting to standing.
Clinically, it is defined as a drop of at least 20 mmHg systolic or 10 mmHg diastolic within three minutes of standing.
Here is why it happens:
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When a person stands, gravity pulls blood toward the legs.
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This briefly reduces the amount of blood returning to the heart.
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Blood pressure drops for a moment.
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Normally, the nervous system quickly corrects this drop by tightening blood vessels and increasing heart rate.
Most people barely notice this temporary change.
However, some individuals do not compensate well. They may experience:
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Light-headedness
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Dizziness
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Fainting
This is an important safety concern, especially in older adults, because fainting can lead to serious falls and injuries.
| Feature | Hypertension (High BP) | Hypotension (Low BP) |
|---|---|---|
| Frequency | Very common | Less common |
| Symptoms | Often none (“silent”) | Often dizziness, fainting |
| Main concern | Long-term organ damage (heart, brain, kidneys) | Not enough blood flow to organs right now |
| Serious risks | Heart attack, stroke, kidney failure | Falls, injury, shock (especially in older people and people who have been bedridden for extended time periods. |
| Why it matters | Chronic strain on vessels and heart | Immediate lack of perfusion |
In Short:
- Hypertension is dangerous because it causes long-term damage silently.
- Hypotension is dangerous when it reduces blood flow to organs or causes fainting and falls.
Both conditions matter, but hypertension is the bigger public-health threat, while hypotension is more about immediate safety and perfusion.