Hypertension Types of Hypertension Epidemiology Etiology Pathophysiology Symptoms Diagnosis Treatment Prevention
INTRODUCTION TO CARDIOVASCULAR SYSTEM
The heart is muscular organ about the size of a closed fist located in the chest between the lungs behind the sternum and above the diaphragm. It is surrounded by the pericardium. On its superior end, the base of the heart is attached to the aorta, pulmonary arteries and veins, and the vena cava. The inferior tip of the heart, known as the apex, rests just superior to the diaphragm. The base of the heart is located along the body’s midline with the apex pointing toward the left side. Because the heart points to the left, about 2/3 of the heart’s mass is found on the left side of the body and the other 1/3 is on the right.
Heart is the pump which is responsible for maintaining adequate circulation of
oxygenated blood around the vascular network of the body. It takes in deoxygenated blood through the veins and delivers it to the lungs for oxygenation before pumping it into the various arteries.
Hypertension is a chronic medical condition that arises when the blood 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”). 1 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 Etiology
The exact causes of high blood pressure
are not known, but several factors and
conditions may play a role in its
• Being overweight or obese
• Lack of physical activity
• Too much salt in the diet
• Too much alcohol consumption
• People with family members who
have high blood pressure
• Chronic renal failure
• Adrenal and thyroid disorders
Many people with kidney disorders have
secondary hypertension. The kidneys
regulate the balance of salt and water in the body if the kidneys cannot rid the body of excess salt and water, blood pressure goes up.Kidney infections, a narrowing of the arteries that carry blood to the kidneys, called renal artery stenosis and other kidney disorders can disturb the salt and water balance.
Cushing’s syndrome and tumors of the
pituitary and adrenal glands often increase levels of the adrenal gland hormones like cortisol, adrenaline and aldosterone, which can cause hypertension.
Certain medications, such as birth
control pills, cold remedies, decongestants, over-the-counter pain relievers and some prescription drugs, illegal drugs, such as cocaine and amphetamines or chronic alcohol use, obstructive sleep apnea and pregnancy may lead to hypertension.
Hypertension causes three major
circulatory abnormalities: increased
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.