What is hypertension?
Hypertension or high blood pressure is the increased rise in the pressure of blood in the arteries. It increases the risk of associated cardiovascular (heart) diseases such as stroke, myocardial infarction, failure of kidneys or heart, other vascular complications.
What are the blood pressure ranges?
Normal pressure of blood according to current guidelines is < 130 and < 85. In hypertension the treatment is influenced by the presence of other risk factors such as pre-existing heart diseases and diabetes.
A list of the hypertension ranges from normal to risk levels are given in the table below;
Systolic (mm Hg)
Diastolic (mm Hg)
Isolated systolic hypertension
Source: J Hypertens 1999; 17(2): 151-183
What is blood pressure?
The heart supplies oxygenated or pure blood to all parts of the body through the help of vessels called arteries. The force with which the blood pushes against the walls of the artery is known as BP.
The heart pumps blood into the arteries as it is beating. The pressure exerted on the artery walls when it is being filled with blood is known as systolic pressure and is 120 normally.
The heart relaxes between the beats or pumping the blood into the arteries. This is the time when the pressure falls, and is known as diastolic pressure. The diastolic pressure is normally 80.
What causes hypertension?
Majority (about 95%) of patients have essential hypertension or primary hypertension. The main reasons behind this hypertension are known to be;
Genetic factors: hypertension tends to run in families and children of hypertensive parents tend to have a greater tendency of hypertension.
Fetal factors: low birth weight is known to be associated with subsequent hypertension. This may be due to the fact that the fetus adapts to the intrauterine under nutrition and which may bring about long term changes in the blood vessels.
Obesity: fat people are at a greater risk of hypertension as compared with normal people. Fat or obese people also show abnormal sleep tendencies which may cause further complications of hypertension.
Alcohol intake: research has shown a close association between alcohol consumption and increased pressure.
Sodium intake (salt intake): a high sodium intake is a major factor in increased BP. A shift from rural to urban lifestyle is also associated with an increase in salt uptake and hence an increase in the risk of high BP.
Stress: acute pain or stress can rise blood pressure, but the role of chronic stress in hypertension is still unknown.
Vitamin D deficiency
Changes in autonomic nervous system: the autonomic system is known to bring about indirect changes in the blood pressure levels.
Insulin resistance or Type II Diabetes: insulin resistance causes increased levels of insulin in blood, an intolerance of body towards glucose, decreased levels of high density lipids and all this is known to cause an increased risk of cardiovascular diseases including hypertension.
Remaining percentage of population has secondary hypertension which is caused as a result of underlying 高血壓飲食 diseases. This is known as secondary hypertension and it has a cause which can be essentially treated. These are;
Renal diseases such as diabetic nephropathy
Cardiovascular diseases which are there by virtue of birth
Use of drug e.g. oral contraceptive pills, steroids, NSAID’s, liqourice and vasopressin. These drugs may either cause hypertension or interfere in the action of drugs acting against hypertension.
Pregnancy: pregnancy induced hypertension is a disorder which goes after the delivery of the baby. Sometimes the hypertension is followed with an increased concentration of proteins in the urine. This condition is known as pre-eclampsia and may be fatal to the mother.
What are the symptoms of hypertension?
Sometimes the person with high BP can go for years without showing any outwardly symptoms. Therefore it is important that people go for regular checkups to avoid complications later on. The symptoms if at all present are;
Blood in the urine
What are the target organs affected?
The target organs that are prone to be damaged as a result of prehypertension and systemic hypertension are kidney, other cardiovascular organs, and brain & retina. Various diseases that can be caused as a result of chronic hypertension are chronic kidney disease, myocardial infarction, congestive heart failure, dementia, stroke, ventricular tachycardia and fibrillation.