Hypertension
Normal blood pressure is maintained at readings below 120/80. Within this range, the heart and blood vessels are at their best in supplying precious blood to vital organs. When blood pressure readings exceed 120/80, the risk of injury to the heart, vessels and the organs they supply rises. Persistently high blood pressures (hypertension) eventually cause injury to the heart and blood vessels at first, then the organs supplied by the damaged blood vessels.
Potential Damage
The heart is built to work under only limited pressure. At higher pressures, the heart has to work harder to push blood through the arteries and arterioles (end-point vessels in the tissues). The heart muscles thicken initially to meet this challenge, increasing the size of the heart. As the pressure persists or increases, the heart begins to get fatigued and the increased stiffness that follows the thickening of the walls also interferes with its function. When it is no longer able to function as an efficient pump, blood supply to vital organs is compromised, a condition called cardiac failure. The enlarged heart also demands more blood supply, making it more vulnerable to insufficiency in blood flow and prone to heart attacks.
Persistently increased pressure in the arteries leads to small, linear tears. The tears can form plaques by attracting platelets and trapping other floating debris like cholesterol and fat particles, thus narrowing the blood vessels. This is called atherosclerosis. These narrowed portions of the blood vessels are also easily blocked by floating clots. The plaques can rupture and float away as clots to block other narrowed blood vessels or small arterioles. The wounds in the arteries can also balloon into aneurysms that may rupture and bleed. The overall effect is a diminishing blood supply to vital organs.
In the presence of certain conditions like obesity, diabetes, high blood cholesterol and tobacco use, the speed and severity of the damage of high blood pressure is increased.
Clinical Effects
High blood pressure is the most important risk factor of coronary artery disease and resultant heart attacks. As the struggling heart tackles diminishing blood supply from narrowed arteries, the first sign is Angina pectoris, which may not even be recognized before the actual usually fatal "heart attack" as a portion of the heart is cut off from supply and dies. Heart failure, as a sequel to the heart attack or following the progressive weakening of the heart, shows up first as breathlessness on mild exertion. This can progress to breathlessness at rest and an inability to lie down flat in extreme cases.
Different organs show signs of diminished blood flow differently. The kidneys gradually drop in function until they are totally unable to clear toxins from the blood. The kidneys try to protect its blood supply by releasing agents that further increase blood pressure, making matters much worse.
Blindness results when the eyes are affected, either suddenly as vessels to the retina rupture or gradually, as they are narrowed.
In the brain, the narrowed blood vessels can occasionally be occluded temporarily, leading to warning fainting spells or loss of brain function. Total occlusion leads to complete, often permanent loss of function or stroke. Multiple, sub-clinical strokes can result in dementia.
Aneurysms, wherever they occur, have a tendency to rupture. In the aorta, the rupture causes massive, life-threatening hemorrhage. In the brain, intracranial hemorrhage results with dire consequences.
Prevention
A lot of the damage of untreated high blood pressure is irreversible. Thus, like never before, an ounce of prevention is better than tons of cure. The beginning here is with the measurement of blood pressure and continuous monitoring. Knowledge of risk factors and how to avoid them is crucial in avoiding this silent killer. Treatment will depend on individual cases and the physician's assessment. High blood pressure should not be left untreated. It causes almost 2,000 deaths a month in the U.S. alone.
