high blood pressure
Meaning of high blood pressure: Nothing is usually felt, so damage to the vessels of the eyes, kidneys and brain accumulates long before anything announces it.
Definition of high blood pressure
High blood pressure, also called hypertension, is a sustained rise in the force circulating blood exerts against artery walls. Blood pressure is written as two numbers, the pressure while the heart contracts over the pressure between beats. The diagnosis rests on repeated readings above a threshold defined by clinical guidelines rather than on any single measurement.
What raises it?
| Type | What lies behind it |
|---|---|
| Primary | No single identifiable cause; builds gradually and accounts for most cases. Age, family history, body weight, salt and alcohol intake, and inactivity all contribute |
| Secondary | A specific underlying cause, including kidney disease, narrowing of a kidney artery, hormone producing adrenal conditions, thyroid disorders, obstructive sleep apnea, and certain medicines and stimulants |
The distinction is practical. Secondary causes are looked for when pressure rises abruptly, appears at an unusually young age, reaches extreme levels, or fails to respond to several treatments, because in those cases the underlying problem can often be corrected directly.
Why is it silent?
Arteries carry no sensory nerves reporting pressure the way skin reports heat, so nothing signals a rise. Headache, nosebleeds and dizziness are commonly attributed to hypertension, yet they occur at much the same rate in people whose readings are normal, except at extreme levels. The condition is therefore found by measurement, and measurement has its own pitfalls: readings run higher in a clinical setting than at home for some people, a cuff too small for the arm reads high, and a single value in any setting says little. Home readings and monitoring across a full day and night are used to settle the question when a clinic reading is in doubt.
What damage does it do?
Pressure works on the vessels themselves. Artery walls thicken and stiffen, which raises pressure further. The left side of the heart thickens against the extra load and eventually struggles to fill and empty properly. The filtering units of the kidney are damaged by the pressure they receive, and failing kidneys raise blood pressure in turn. Small vessels in the retina narrow and leak. Sustained pressure also weakens vessel walls in the brain, contributing both to strokes caused by blockage and to those caused by bleeding, and to the widening and tearing of the aorta.
Also known as
Used in a sentence
Routine screening revealed a blood pressure reading consistent with high blood pressure, prompting further monitoring.
Good to know
The numeric threshold defining high blood pressure has been revised as guidelines were updated, so a reading once treated as normal may fall into a different category under a more current guideline.
Word origin
Where “high blood pressure” comes from
Formed from hyper-, Greek for over or above, and tension, from Latin tendere, meaning to stretch, reflecting the increased force within the blood vessels.