Hypertension (High Blood Pressure)
A person is said to have high blood pressure when the average arterial pressure under resting conditions is greater than 110 mm Hg. In order to define high blood pressure more accurately, blood pressure is measured as two numbers, i.e. the "diastolic" pressure (when the heart beats) and the "systolic" pressure (in between heart beats). Hypertension is present when the systolic pressure is greater than 135 mm Hg and the diastolic pressure is above 90 mm Hg. In severe hypertension, the systolic pressure can be as high as 250 mm Hg and the diastolic pressure is above 130-140 mm Hg.
Causes of Hypertension
Numerous studies have shown that hypertension rarely occurs on its own, but that it can be related to other problems in the body. Most frequently, high blood pressure occurs when the kidneys fail to excrete sufficient amounts of salt and water. The blood pressure rises in order for the kidneys to excrete normally. This situation can be caused by water and salt retention or by an activation of the mechanisms that regulate blood vessel constriction or a combination of both. Therefore, high blood pressure is usually defined as two extreme types:
- Volume-loading Hypertension: Caused by reduced kidney functioning and increased salt intake
- Vasoconstrictor Hypertension: When high levels of vasoconstrictors enter the blood stream. These are usually angiotensin II, norepinephrin and epinephrin
However, in most patients no underlying cause for high blood pressure can be found and these patients are said to have "essential hypertension".
Effect of Lifestyle on Hypertension
Our way of life can aggravate hypertension. Chronic stress activates the hypothalamus-pituitary-adrenal axis (HPA-axis) and thereby has a negative effect on high blood pressure. Stimulation of the adrenal glands increases the secretion of vasoconstrictors angiotensin II, norepinephrin and epinephrin. A diet containing too much salt can increase hypertension further. Consuming too much alcohol, too much caffeine and smoking can all elevate blood pressure further. Also, chronic use of over-the-counter pain killers (NSAIDs) can contribute to hypertension. Other health conditions such as obesity, diabetes or having high cholesterol, can also contribute to high blood pressure.
Health Risks of Hypertension
Hypertension can have severe effects on the body. It can increase the chance for a stroke or heart attack, it can lead to kidney failure and can severely damage the retina of the eye. Symptoms of high blood pressure often go unnoticed, and therefore hypertension is called the "silent killer". However, if you suspect high blood pressure or you experience light-headedness in combination with shortness of breath and heart pain or heart palpitations, see your doctor immediately.