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Diagnostic Service > Detection of Risk Factors for Coronary Artery Disease (CAD)
BLOOD PRESSURE
Why When How Before

Why is it done?

High blood pressure, also called hypertension, occurs due to narrowing of smaller blood vessels (known as the arterioles), which causes the blood to exert excessive pressure against the vessel walls. The heart must therefore work harder to maintain this higher pressure. High blood pressure causes symptom by itself and in long term can affect other organs of the body. Although the body can tolerate increased blood pressure for months and even years, eventually the heart can enlarge and be damaged (a condition called hypertrophy), and injury to blood vessels in the kidneys, the brain, and the eyes can occur.

It is important to understand implications of high blood pressure to understand why it is important for an individual to keep an eye on his/her blood pressure. Two numbers are used to describe blood pressure:

  • Systolic. The systolic pressure (the higher and first number) measures the force that blood exerts on the artery walls as the heart contracts to pump out the blood.
  • Diastolic. The diastolic pressure (the lower and second number) is the measurement of force as the heart relaxes to allow the blood to flow into the heart.

For example, optimal blood pressure is less than 120/80 mm Hg (systolic/diastolic). Blood pressure is now categorized as:

  • Optimal
  • Normal
  • High normal
  • Hypertensive

Experts now believe that the health dangers from blood pressure varies in different age groups depending on whether systolic or diastolic pressure is elevated:

  • Abnormally higher diastolic pressure is a strong predictor of heart attack and stroke in young adults and in people with essential hypertension (a disease process from unknown causes that increases resistance in the blood vessels).
  • Abnormally elevated systolic blood pressure (the first and higher number) appears to be a significant indicator for heart complications in middle-aged and older adults. In fact, evidence suggests that elevated systolic pressure poses a significant danger for heart events and stroke events when diastolic is normal, a condition called isolated systolic hypertension . The wider the spread between the systolic and diastolic measurements, the greater the danger.
What to do for a specific finding ?
Blood Pressure Category Ranges for Most Adults (systolic/diastolic) Advisable action after Initial Diagnosis
Optimal Blood Pressure (systolic/diastolic) Systolic below 120 mm Hg Diastolic below 80 mm Hg No action.
Normal Blood Pressure Systolic 120 to 130 mm Hg Diastolic 80 to 85 mm Hg (The upper numbers should be minimum goal for everyone, particularly people with diabetes.) Rechecked every two years.
High Normal Blood Pressure Systolic 130 to 139 mm Hg Diastolic 85 to 89 mm Hg Blood pressure monitored at home and patient should be evaluated for organ damage.
Hypertension (High Blood Pressure) Systolic above 140 mm Hg Diastolic above 90 mm Hg (In middle age and older people, systolic pressure above 140 mm Hg suggests higher health risks even when diastolic pressure is normal or low.)  
Mild Hypertension (Stage 1) Systolic 140 to 159 mm Hg Diastolic 90 to 99 mm Hg Same as high normal. If no organ damage, retesting at least twice a week for several weeks. If organ damage present, start drug therapy.
Moderate Hypertension
(Stage 2) 		Systolic 160 to 179 mm Hg Diastolic 100 to 109 mm Hg Same as high normal. If no organ damage, retesting at least twice a week for several weeks. If organ damage present, start drug therapy.
Severe Hypertension
(Stage 3) 		Systolic 180 to 209 mm Hg Diastolic 110 to 119 mm Hg Same as high normal. Consider immediate drug therapy regardless of organ damage evidence.
Very Severe Hypertension
(Stage 4)		 Systolic greater than 210 mm Hg Diastolic greater than 120 mm Hg Same as high normal. Consider immediate drug therapy regardless of organ damage evidence.
Note: If one measurement is normal and the other elevated, the higher category of either measurement is usually used to determine severity. For example, if systolic pressure is 165 (moderate) and diastolic is 92 (mild), the patient would still be diagnosed with moderate hypertension. It should be strongly noted that a high systolic pressure compared to a normal or low diastolic pressure should be a major focus of concern in most adults.