Eliminate stroke risk factors and eliminate stroke

Nutrition Health Review, Summer, 1996

In an ideal world, strokes would not happen in the first Place. Many strokes are largely preventable and can be averted by modifying risk factors.

Hypertension

Untreated hypertension is the leading cause of strokes in the United States, and controlling blood pressure is probably the most powerful weapon in the preventive arsenal.

High blood pressure damages vessel walls, encouraging scarring, plaque buildup, and atherosclerosis (narrowing of the arteries). Because high blood pressure rarely causes symptoms, it is often called "the silent killer," and a blood pressure check is recommended at least every two years. Normal blood pressure is considered to be 130/ 85 mm. Hg. or less.

Blood pressure measurements are written as a pair of numbers: the systolic ("top") number is a measure of the pressure exerted against the arterial walls when the heart contracts, and the diastolic ("bottom") reading is the pressure between contractions.

Hypertension can sometimes be lowered by lifestyle changes alone, such as reducing salt intake, exercising more frequently, and losing weight. Often these modifications need to be combined with an antihypertensive medication, such as diuretics, beta blockers, alpha blockers, or angiotensin-converting enzyme (ACE) inhibitors.

Atrial Fibrillation

Atrial fibrillation is a common heart rhythm disturbance, or arrhythmia, that affects about two million people in the United States. For reasons not fully understood, the upper chambers of the heart (the atria) quiver erratically instead of beating forcefully and predictably, making it difficult to expel all the blood in the ventricles. The stagnant blood in the left atrium may form clots that can cause a stroke if they break loose and make their way to the brain.

Recent investigations have shown that warfarin, a drug that inhibits blood clot formation, can dramatically reduce the risk of stroke in people with atrial fibrillation.

Atherosclerosis and Elevated

Cholesterol Levels

Atherosclerosis is the hardening and thickening of arteries that occurs when cholesterol, cellular waste products, calcium, and other substances collect along the inner lining. When atherosclerosis narrows the coronary arteries, which supply the heart muscle with blood, the lack of oxygen can cause angina pectoris (sudden pain in the chest and arms or jaw) or a myocardial infarction (heart attack). Atherosclerosis that affects the coronary. arteries is also likely to affect the carotid arteries, setting the stage for an ischemic stroke. Since cholesterol contributes, to atherosclerotic plaque, it is not surprising that elevated levels are associated with an increased risk of ischemic stroke.

A person's total cholesterol measurement can be classified into one of three categories: 200 milligrams per deciliter (mg./dl.) or lower is "desirable," 200 to 239 mg./dl. is "borderline," and 240 mg./dl. or greater is "high." Measuring total cholesterol levels as well as high-density lipoprotein (HDL) cholesterol is recommended every five years starting at age 35.

The safest and cheapest way to treat high cholesterol is to change one's eating habits. Total cholesterol can be lowered by reducing dietary fat to a maximum of 30 percent of calories and limiting saturated fat to less than 10 percent of calories.

Transient Ischemic Attacks

Approximately 10 percent of all strokes are preceded by a transient ischemic attack (TIA), and about one third of people who have a TIA will have a stroke within the next five years. A TIA requires immediate medical attention, and people who have had one should consult a doctor about steps that may prevent a full-scale stroke. (See page 2 for more information on TIAs.)

Myocardial Infarction

When someone has had a heart attack, there is a chance that a blood clot will form at the site of the infarction, break off, and travel to the brain where it May obstruct that organ's blood supply. About 3 to 4 percent of people who have a heart attack go on to have an embolic stroke, almost all of them occurring during the first month after the heart attack.

Stroke risk is also higher for people with other heart conditions that increase the chance of clot formation, such as congestive heart failure, left ventricular hypertrophy (thickening of the wall of the left ventricle), valve disease, or arrhythmias. Proper treatment of these conditions can help prevent stroke.

Diabetes

Diabetes increases the risk of ischemic stroke to 1.8 to 3 times that of people without the disease. This appears to be due to a greater susceptibility to high blood pressure, atherosclerosis, and an increased tendency to form clots. Although it is unclear whether keeping blood glucose levels within normal limits can reduce the risk of stroke, it is known that people with diabetes who keep their blood sugar under tight control are less likely to suffer severe brain damage if they do have a stroke. People with a family history of diabetes should talk to their physician about having their blood glucose levels tested.