Hypertension

HYPERTENSION 

Hypertension is a chronic medical condition that arises when theblood pressure is abnormally high (greater than 140 mm of Hg systolic and 90 mm of Hg diastolic). 

Hypertension occurs when the body’s smaller blood vessels (the arterioles) narrow, causing the blood to exert excessive pressure against the vessel walls and forcing the heart to work harder to maintain the pressure. Although the heart and blood vessels can tolerate increased blood pressure for months and even years, eventually the heart may enlarge (a condition called hypertrophy) and be weakened to the point of failure. 

Hypertension risk factors include obesity, drinking too much alcohol, smoking and family history. 

Blood pressure is actually a measure of two pressures, the systolic and the diastolic. The systolic pressure is the force that blood exerts on the artery walls as the heart contracts to pump the blood to the peripheral organs and tissues. The diastolic pressure is residual pressure exerted on the arteries as the heart relaxes between beats. A diagnosis of hypertension is made when blood pressure reaches or exceeds 140/90 mmHg (read as “140 over 90 millimetres of mercury”). 

Types of Hypertension 

There are two major types of hypertension and four less frequently found types. 

1. Primary (Essential) Hypertension: 

About 95% of people with high blood pressure have essential hypertension or primary hypertension. This condition has no identifiable medical cause. Elevated blood pressure usually begins to appear between age 30 and 50, but can begin at older ages. 

Usually people with essential hypertension have no symptoms, but may 

experience frequent headaches, tiredness, dizziness, or nose bleeds. Although the cause is unknown, but contributing factors for essential hypertension may be, obesity, smoking, alcohol, diet and inherited. 

2. Secondary Hypertension: About 5%-10% of people with high blood pressure have secondary hypertension. This condition has definite cause; the most common cause of secondary hypertension is an abnormality in the arteries supplying blood to the kidneys. Other causes include airway obstruction during sleep, diseases and tumors of the adrenal glands, hormone abnormalities, thyroid disease, and too much salt or alcohol in the diet. Drugs can cause secondary hypertension, including OTC medications such as ibuprofen and pseudoephedrine. 

Pathophysiology 

Hypertension causes circulatory abnormalities: arteriolar resistance, increased large artery stiffness, and early or premature reflection of arterial pulse waves.
Increased resistance and vessel stiffness in younger hypertensive patients result from structural changes, including thinning and fracturing of elastin, increased collagen deposition, and increased wall thickness. These changes manifest primarily as a greater rise in systolic pressure greater than diastolic pressure.
There are many known conditions that can cause secondary hypertension. Regardless of the cause, arterial pressure becomes elevated either due to an increase in cardiac output, an increase in systemic vascular resistance, or both. When cardiac output is elevated, it is generally due to either increased neurohumoral activation of the heart or increased blood. Increased systemic vascular resistance is most commonly caused, at least initially, by increased sympathetic activation or by the effects of circulating vasoconstrictors (e.g., angiotensin II). Anatomic considerations, such as narrowing of the aorta (e.g., coarctation) or chronic changes in vascular structure (e.g., vascular hypertropy) can also cause or contribute to increased systemic vascular resistance. Renal artery disease can cause because of narrowing of the vessel lumen (stenosis). 

Symptoms 

High blood pressure usually causes no symptoms and high blood pressure often is labelled “the silent killer”. People who have high blood pressure typically do not know it until their blood pressure is measured. 

Sometimes people with markedly elevated blood pressure may develop: 

• Headache

• Dizziness

• Blurred vision

• Nausea and vomiting, and

• Chest pain and shortness of breath.

Prevention 

Having high blood pressure can be prevented by eating healthily, maintaining a healthy weight, taking regular exercise, drinking alcohol in moderation and not smoking, reducing salt intake, managing stress.