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| Image Credit: By Steven Fruitsmaak [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], from Wikimedia Commons |
Blood Flow and Blood Pressure
Blood carries oxygen and nutrients to all body parts and flows within structures called blood vessels. Continuous blood flow to all body parts requires the pumping action of the heart. Blood vessels are of two main types: "Arteries and Veins".
Arteries carry blood rich in oxygen from the heart to the body. As arteries receive blood from heart, they carry blood at high pressure and they are structurally supported by their thick walls to contain the high-pressure blood flow. Veins on the other hand, carry the blood back to the heart from the body. Venous blood flow has a much lower pressure and thus veins have thinner walls as compared to arteries.
Until unless otherwise specified, the term "Blood Pressure (BP)" refers to the pressure of blood flow within the arteries. The normal blood pressure reading is generally taken from the artery of the arm, and it commonly ranges from 120 mm to 80 mm of mercury in healthy adults.
As seen above, the blood pressure reading has 2 parts, an upper part, which is measured when the heart contracts to pump the blood and is called a systolic reading (systole=contraction); and a lower part, which occurs when the heart relaxes to fill again with blood and is called a diastolic reading (diastole=relaxation). BP readings are often documented by healthcare professionals as an upper part followed by lower reading and an oblique sign in between, for example, 124/82.
Hypertension and Pre-hypertension
Hypertension refers to the presence of abnormally high blood pressure measurements continuously and repeatedly. Hypertension is diagnosed when a person shows multiple and periodic elevated readings both in a clinical setting as well as in the home and a single elevated reading, especially at a clinic is not sufficient to label somebody with hypertension.
Generally, a BP reading higher than 140/90 is considered to fall under the umbrella of hypertension by experts because BP values higher than 140/90 have shown the bad effect of reducing longevity or causing complications like heart disease, stroke, and kidney disease.
So, while the normal value is 120/80, and hypertension refers to values over 140/90, one can find a grey zone in between i.e. from systolic 121 to 139 and diastolic 81 to 89. These intermediate values are not considered normal, but, they also do not show clearly increased risk of death or complications, hence they are not considered as hypertension.
Such intermediate readings are sometimes labeled as Pre-hypertension or simply as elevated blood pressure. People with Pre-hypertension are periodically tested for hypertension and lifestyle changes to control blood pressure are recommended in these individuals.
Recently, the American Heart Association deviated from the norm and recommended a different approach. The new guidelines broke this grey zone into two different groups. While people with BP 121-129 continued to be labeled as Pre-hypertension, people with either systolic BP 131-139 or Diastolic BP 80-89 were grouped as people with hypertension. While, it recommended lifestyle changes for both groups, the guideline-recommended early medical treatment in the second group in case of pre-existing heart disease, stroke, diabetes, etc.
Such intermediate readings are sometimes labeled as Pre-hypertension or simply as elevated blood pressure. People with Pre-hypertension are periodically tested for hypertension and lifestyle changes to control blood pressure are recommended in these individuals.
Recently, the American Heart Association deviated from the norm and recommended a different approach. The new guidelines broke this grey zone into two different groups. While people with BP 121-129 continued to be labeled as Pre-hypertension, people with either systolic BP 131-139 or Diastolic BP 80-89 were grouped as people with hypertension. While, it recommended lifestyle changes for both groups, the guideline-recommended early medical treatment in the second group in case of pre-existing heart disease, stroke, diabetes, etc.
About the author: Dr. Naval Asija is a licensed MBBS Physician from India. MBBS is the equivalent of the MD degree offered by international medical schools. He is based in Delhi, India, and works as a medical writer, editor, and consultant. He supports medical researches as an author's editor, medical communication companies involved in medico-marketing activities, and medical technology companies in improving their products. He can be contacted via his LinkedIn Profile: https://www.linkedin.com/in/navalasija/
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