Blood pressure is measured in millimeters of mercury (mm Hg). A blood pressure measurement has two numbers: The top number (systolic) is the pressure of the blood flow when your heart muscle contracts, pumping blood. The bottom number (diastolic) is the pressure measured between heartbeats.
Why is blood pressure measured in mm Hg
The abbreviation mm Hg stands for millimeters of mercury. Mercury was used in the first accurate manometers and is still used in medicine today as the standard unit of measurement for pressure.
Taking your pulse versus checking your blood pressure
While both are indicators of health, blood pressure and heart rate (pulse) are two separate measurements.
Blood pressure categories
The five blood pressure ranges recognized by the American Heart Association are:
Normal
Blood pressure values less than 120/80 mm Hg are considered within the normal range. If your results fall into this category, stick with heart-healthy habits like eating a balanced diet and exercising regularly.
High
Elevated blood pressure is when readings consistently range between 120-129 systolic and less than 80 mm Hg diastolic. People with high blood pressure are likely to develop high blood pressure unless steps are taken to control the condition.
Stage 1 hypertension
Stage 1 hypertension is when the blood pressure constantly varies from 130 to 139 systolic or 80 to 89 mm Hg diastolic. At this stage of high blood pressure, doctors will likely prescribe lifestyle changes and consider adding blood pressure medications based on your risk for atherosclerotic cardiovascular disease (ASCVD), such as a heart attack or stroke. .
Stage 2 hypertension
Stage 2 hypertension is when your blood pressure constantly oscillates between 140/90 mm Hg or higher. At this stage of high blood pressure, doctors will likely prescribe a combination of blood pressure medications and lifestyle changes.
Hypertensive crisis
This stage of high blood pressure requires medical attention. If your blood pressure readings suddenly go above 180/120 mm Hg, wait five minutes and then take your blood pressure again. If your readings are still unusually high, contact your doctor immediately. You could be experiencing a hypertensive crisis.If your blood pressure is above 180/120 mm Hg and you are experiencing signs of possible organ damage such as chest pain, shortness of breath, back pain, numbness / weakness, vision changes, or difficulty speaking, don't wait to See if your pressure drops on its own. Go to a medical center.
Your blood pressure numbers and what they mean
Your blood pressure is recorded as two numbers:
Which number is more important?
Typically, more attention is given to systolic blood pressure (the first number) as a major risk factor for cardiovascular disease for people over 50. In most people, systolic blood pressure rises steadily with age due to the increasing stiffness of large arteries, long-term buildup of plaque and an increased incidence of cardiac and vascular disease.
However, either an elevated systolic or an elevated diastolic blood pressure reading may be used to make a diagnosis of high blood pressure. According to recent studies, the risk of death from ischemic heart disease and stroke doubles with every 20 mm Hg systolic or 10 mm Hg diastolic increase among people from age 40 to 89.