Congestive Heart Failure
Imagine a worker who has the job of pumping water up a 20-foot (ft) pipe. He can do this easily. Suddenly he's asked to pump water up a 10-story building. The effort of pumping against the enormous increase in pressure will wear him out. For a time his muscles will enlarge as he struggles with the abnormal load, but finally, he'll be exhausted and he won't be able to pump water out of his pipe as fast as it flows in. The water will back up and there will be flooding somewhere in the system. This is exactly what happens to the left ventricle when it has to pump against a high pressure. At first the muscle wall thickens in an attempt to compensate , but finally the heart fails: it can't pump blood out into the aorta as fast as it runs in from the lungs, and the pressure backs up into the lungs with congestive heart failure. This can happen abruptly: it is common to see a hypertensive patient who has been substantially free of symptoms suddenly go into massive pulmonary edema. Most cardiologists would probably tell you this is statistically the commonest cause of abrupt, life-threatening left heart failure. It is not clear why the break in cardiac compensation is so abrupt or why patients tolerate a high blood pressure so long without warning symptoms, but the phenomenon of sudden, life-threatening pulmonary edema in a hypertensive patient is familiar to every emergency department physician.
Stroke
The word stroke is the same as the medical term cerebrovascular accident. It means that the blood supply to some part of the brain has been cut off. This can happen because a blood vessel ruptures and bleeds or because a vessel becomes plugged in some way. Hypertension puts an enormous strain on the smaller arteries, and they can simply rupture. The result is like having a nosebleed in the brain: a certain amount of brain tissue loses its blood supply and the cells die. When the blood supply to brain cells is cut off, they begin to die within 10 minutes. The effect on the patient, of course, depends on which cells are affected: there may be paralysis of major parts of the body or there may be no more than a temporary blurring of consciousness.
It's frightening to think that the effects of a stroke are a matter of simple chance the results depend on which blood vessel ruptures and where in its course the rupture occurs. Hypertension was once the commonest cause of stroke, but with better medical agents and better treatment there has been a very encouraging drop in the occurrence of hypertensive strokes in recent years. In fact, the partial conquest of hypertensive stroke has been one of the major advances of modern medicine, much more important in long-term effect than all the spectacular advances in cardiac surgery.
Coronary Artery Disease
The cells that form the lining of the coronary arteries are often damaged when the pressure within the vessel is abnormally high. They begin to degenerate, and masses of fat, or atheromas, are likely to form, tending to block the flow of blood through the vessel. Patients with hypertension face at least a 200% increase in risk of coronary artery disease. Why does hypertension affect the lining of the coronary arteries? The answer is not at all clear, but the association is established beyond question. Does control of blood pressure prevent coronary disease? It's reasonable to think so, but the results so far are not as clear-cut as in the prevention of stroke: more data are needed.
Kidney Failure
This is a chicken-and-egg situation. High blood pressure can certainly produce damage in the blood vessels of the kidneys, often with severe kidney failure. On the other hand, kidney disease can produce high blood pressure. Sometimes it is hard to tell which caused which.
When an intelligent physician detects high blood pressure, it's not an end point; it's the signal for a swift clinical investigation:
- What kind of hypertension is present? Mild and relatively benign? Severe and dangerous?
- What associated diseases are present?
- What complications are present?
- Can a specific cause be found?
Note: Practically all these complications can be prevented by controlling high blood pressure.
That's what we are talking in the next posts
That's what we are talking in the next posts
