Diseases of the Blood Vessels - The vessel-clogging disorders



Atherosclerosis

Varicose Veins

Atherosclerosis (hardening of the arteries) is the nation's most serious health problem, the underlying cause of a million or more deaths each year from heart attack and stroke. It is the process whereby fats carried in the bloodstream gradually pile up on the walls of arteries, like rust in a pipe. The vessels become brittle and roughened; the channel through which blood flows grows narrower. Eventually the organs and tissues supplied by the diseased arteries may be sufficiently deprived of their normal oxygen delivery so as to interfere with proper function. Such a cutback in the pipeline supply is called ischemia . This fat deposit poses its greatest hazard when it occurs in the vessels serving the heart, brain and, sometimes, the lower extremities.

Atherosclerosis and Its Influence in Thrombosis, Storke, and Embolus

A reduced supply of blood to the lower extremities may cause irreversible damage and ultimately lead to death of the leg tissues unless proper circulation is restored. Bacterial invasion may follow; the area may swell, blacken, and emit the distinctly offensive smell of the deadly infection. Such a condition is known as gangrene , a severe disorder that may require amputation above the site of blockage if other measures, including antibiotic therapy, fail. Diabetics more commonly than others may develop atherosclerotic obstructions in leg arteries. Such persons must take care to avoid leg injuries, because even minimal damage in an already poorly served tissue area can bring on what is termed diabetic gangrene .

When the coronary arteries nourishing the heart are involved, even a moderate reduction in blood delivery to the heart muscle may be enough to cause angina pectoris, with its intense, suffocating chest pains.

Thrombosis

Thrombosis, a blood clot that forms within the vessels, is a great ever-present threat that accompanies atherosclerosis. The narrowed arteries seem to make it easier for normal blood substances to adhere to the roughened wall surfaces, forming clots. If the clot blocks the coronary arteries, it may produce a heart attack—damage to that part of the heart deprived by vessel obstruction. For a detailed account of atherosclerosis and heart attack, see under Ch. 10, Heart Disease .

Stroke

Stroke, like heart attack, is a disorder usually resulting from blockage brought on by the atherosclerotic process in vessels supplying the brain. This sets the stage for a thrombus , or blood clot fixed within a vessel, which would not be likely to occur in arteries clear of these fatty deposits. A stroke may be a result of an interruption of blood flow through arteries in the brain or in the neck vessels leading to the brain.

Sometimes the shutoff of blood flow, or embolism , may be triggered by a wandering blood clot that has become wedged in cerebral vessels. This kind of clot, known as an embolus , is a thrombus that has broken free into the circulation.

Brain Hemorrhage

A stroke may also stem from hemorrhaging, where a diseased artery in the brain bursts. A cerebral hemorrhage is most likely to occur when a patient has atherosclerosis in combination with hypertension (high blood pressure). (For a discussion of hypertension, see “Hypertensive Heart Disease” in Ch. 10, Heart Disease .) Hemorrhage is also a danger when an aneurysm forms in a blood vessel. An aneurysm is a blood-filled pouch that balloons out from a weak spot in the artery wall. Sometimes, too, pressure from a mass of tissue—a tumor, for example—can produce a stroke by squeezing a nearby brain vessel shut.

When the blood supply is cut off, injury to certain brain cells follows. Cells thus damaged cannot function; neither, then, can the parts of the body controlled by these nerve centers. The damage to the brain cells may produce paralysis of a leg or arm; it may interfere with the ability to speak or with a person's memory. The affected function and the extent of disability depend on which brain region has been struck, how widespread the damage is, how effectively the body can repair its supply system to this damaged area, and how rapidly other areas of brain tissue can take over the work of the out-of-commis-sion nerve cells.

Symptoms

Frequently there are symptoms of impending stroke: headaches, numbness in the limbs, faintness, momentary lapses in memory, slurring of speech, or sudden clumsiness. The presence of these symptoms does not always mean a stroke is brewing; sometimes they are quite harmless. But should they be stroke warning signals, the physician can take some preventive action. He may recommend anticoagulant therapy as well as drugs to bring down elevated blood pressure. In some cases, he might decide to call for surgical replacement of diseased or weakened sections of arteries leading to the brain.

Treatment

Following a stroke, medical personnel may use single photon emission computed tomography (SPECT) to assess quickly the effects of a stroke. A refinement of nuclear scanning (See Chapter 26, Physicians and Diagnostic Procedures ), SPECT shows the nature and extent of brain damage. The next critical step is intensive rehabilitation. Not everyone needs a rehabilitation regimen; some strokes have little effect. Some persons recover quickly from what appears to be a severe stroke. Others may suffer serious damage, and may take a long time to recover even partially. Treatment can usually help—especially those who are partially paralyzed and those with aphasia , the inability to speak properly because of damage to the brain's speech center.



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