What Are The Causes Of High Blood Pressure (Hypertension)

Primary Hypertension: around 90% people with high blood pressure have no identifiable cause for their hypertension. They are said to be having primary hypertension, which was previously referred to as essential hypertension. The actual cause of their hypertension may be a combination of inherited or acquired disorders of the heart or the blood vessels. It can range from an increase in cardiac output due to a fast heart rate, to narrowing of blood vessels which offer resistance to blood flow. An increase in the volume of circulating blood due to fluid retention also may be the cause of hypertension. The factors causing abnormality in the constriction and dilatation of arterioles may be either inherited or may be due to reduction in the chemical substances which bring about these changes. It may also be resulting from excess salt accumulation in the cells interfering with the body’s mechanisms of homeostasis.

 Secondary Hypertension: .Around 15% of people with hypertension has an identifiable cause for their condition, such as kidney or endocrine disorders, and they are said to be having secondary hypertension. Since kidneys play an important part in the control of blood pressure, any of the disorders of the kidneys, have a direct impact on blood pressure regulation. Damage caused to the kidneys by infections or inflammations reduce their ability to regulate the circulating volume of blood, to reduce high blood pressure. Stenosis or narrowing of the renal arteries, either due to injury or atherosclerosis or due to some other disorders of the blood vessels, is a major contributor of high blood pressure. Existing hormonal disorders or hormonal imbalance caused by the use of drugs, such as oral contraceptives may precipitate hypertension. Hyperthyroidism due to an overactive thyroid gland and sometimes hyperaldosteronism caused by a tumor in one of the adrenal glands which produces the hormone aldosterone, are known to cause secondary hypertension. People with Cushing’s syndrome, which causes high levels of the hormone cortisol and those with a tumor in the adrenal glands called pheochromocytoma, which causes high levels of epinephrine and norepinephrine,  also develop secondary hypertension.

Hardening of arteries due to Arteriosclerosis interferes with the body’s mechanism of controlling blood pressure, thus increasing the risk of hypertension. It is due to the fact that the stiff arterial walls offer resistance to body’s attempts to dilate the vessels to bring down the blood pressure to normal levels.

Risk Factors For Hypertension: When people already have a hereditary factor that predisposes them to developing high blood pressure, additional risk factors such as stress, smoking, excessive alcohol consumption, obesity and inactivity may accelerate the process. Emotional stress results in temporary rising of blood pressure but the homeostatic mechanisms of the body soon manage to bring it down to normal levels. Some people who have normal blood pressure at all times, may give a high blood pressure reading at the doctors’ clinic due to the stress of visiting a doctor. This may repeat every time they visit the doctor and this condition is termed as “white coat hypertension”. Even though individual incidences of sudden rising of blood pressure due to a stressful experience is not harmful in itself, repeated incidents may have a cumulative effect which culminates in the development of permanent hypertension. However, this is not a proven fact but a general assumption only.

 Complications Of Hypertension

Damage to the heart and blood vessels due to hypertension may be either structural or functional or both. When the arterial pressure remains very high for an extended period of time, it causes enlargement of the heart. The muscular walls thicken, to help the heart pump with more force against the higher pressure prevailing in the arteries. But the thickening of the walls affect the elasticity of the heart, and after every contraction, the heart does not return to its original size and does not fill up with enough blood. It further increases the load on the heart, as it has to beat more frequently to pump the same quantity of blood, and fast arrhythmias may develop. When the heart’s capacity to pump enough blood to meet the requirement of the body is compromised, heart failure develops.

Atherosclerosis is often a consequence of hypertension, causing thickening and eventually hardening of the arterial walls and narrowing of the main arteries impeding the blood flow to vital organs. This condition predisposes people to kidney failure, heart attack and stroke.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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