Atherosclerosis can occur in any artery. Most commonly it occurs in the aorta, the artery that receives blood directly from the heart. Since the aorta is the largest artery in the body, it is rarely critically narrowed by atheromas. Nonetheless, atherosclerosis can contribute to aneurysms (ballooning of an artery, responsible for only one-fortieth the mortality rate of heart attack -- an aortic aneurysm killed Albert Einstein, who refused to be operated-upon). The most frequent life-threatening problems, however, are caused by the arteries supplying the heart, the brain and the kidneys, in that order. An estimated 70% of North Americans have coronary atherosclerosis (narrowing of the arteries of the heart), although the overt symptoms may not be evident until the arteries are three-quarters occluded. Coronary artery atherosclerosis leads to angina pectoris, heart attack and cardiac arrest. Brain artery atherosclerosis leads to transient ischemic attack (TIA) and stroke.
In angina pectoris (Latin: "strangling in the chest") the coronary vessels narrow temporarily causing the heart muscle to suffer ischemia (lack of oxygen). This is often accompanied by symptoms of crushing, diffuse pain in the chest (directly over the heart), a shortness of breath (air hunger) that leads to gasping, weakness, anxiety, light-headedness, nausea and sweating. The exact same set of symptoms occur in myocardial infarction (heart attack), in which a narrowed coronary artery becomes completely blocked, usually by a blood clot. Heart muscle which formerly received blood from the blocked artery dies if deprived of oxygen for over 40-60 minutes. (An area of dead tissue resulting from a blocked artery is called an infarct). If enough heart tissue dies, the heart may stop altogether (cardiac arrest, also known as sudden cardiac death). Although atherosclerosis is by far the most common cause of heart attack & cardiac arrest, other causes include coronary artery spasm, electrical irregularities and congenital defects.
Transient Ischemic Attack (TIA) is the brain's version of angina. A cerebral artery temporarily narrowed deprives a region of the brain of oxygen. Since only one half of the brain may be affected, paralysis, weakness or lack of sensation on one side of the body is a frequent symptom. Other symptoms include defects of speech, comprehension or vision. Whereas TIA is due to temporary narrowing of a brain artery, stroke results from complete blockage of the artery. In 60% of cases stroke is due to a blood clot formed at the site of blockage, in 20% of cases stroke is due to a clot (embolus) flowing in the bloodstream being wedged in an area of atherosclerotic narrowing, and in 20% of cases stroke is due to bursting of the artery (hemorrhagic stroke, the most dangerous form of stroke).
Everything else being equal, the risk of heart attack is doubled for a diabetic man and increased 5 times for a diabetic woman. Diabetes also doubles the risk of stroke independently from effects of heart disease and high blood pressure -- although good control of blood glucose can reduce the risk.
V. CIGARETTE SMOKING
Heart attacks are 3 to 4 times more likely to occur in a cigarette smoker than in a nonsmoker -- and the smoker's heart attack is more likely to be fatal. The risk of cardiac arrest is 10 times greater for male smokers and 5 times greater for female smokers as it is for nonsmokers. Nonsmoking spouse of smokers have twice the incidence of heart disease and 2.5 times the incidence of lung cancer as nonsmoking spouses of nonsmokers. In the Framingham study, male smokers were 40% more likely to suffer stroke than male nonsmokers and female smokers were 60% more likely to experience stroke than female nonsmokers. The lifespan of a smoker tends to be years less than that of a nonsmoker and the conditions of death are worse for cryonics.
Tobacco smoke contains tar, nicotine, carbon monoxide, benzene, nitrogen dioxide, formaldehyde, hydrogen cyanide, nitrosamines and polycyclic aromatic hydrocarbons -- which are all known to be harmful. Many of these substances are capable of injuring the arterial endothelial cells to begin the atherosclerotic process. Nicotine causes adrenaline (epinephrine) and noradrenaline release, which elevates heart rate and blood pressure. Carbon monoxide binds to hemoglobin 200 times more strongly than oxygen -- thereby reducing the oxygen-carrying capacity of the blood and thickening the bloodstream through compensatory red blood cell proliferation. Smoking lowers the level of beneficial HDL-cholesterol and increases fibrinogen (promoting clotting). Even without coronary atherosclerosis, smoking can lead to cardiac arrest by causing the coronary arteries to go into spasm or by promoting irregularities of heartbeat.
Within one year of quitting smoking, the risk of heart attack falls 50%. Within ten years, ex-smokers who smoked one pack per day or less have the same heart attack risk as those who have never smoked. And the extra risk of stoke is eliminated within 5 years of kicking the cigarette habit.
Groups led by professional counselors have a 35% greater success rate in a period of a year than smokers who try to quit by themselves. Groups that use nicotine chewing gum have an 80% success rate. Most ex-smokers succeed only after several attempts to quit. A positive attitude to take after a failed attempt is to regard the failure as a learning experience -- and to incorporate what was learned by the failure in planning the next attempt. Only one-third of ex-smokers gain weight, and most of those don't keep the extra weight.
VI. HIGH BLOOD PRESSURE (HYPERTENSION)
Blood pressure is regulated by the sympathetic and parasympathetic branches of the autonomic nervous system. In the sympathetic branch, pressure receptors in the aortic arch and the carotid arteries send signals to the vasomotor center of the brain stem. When blood pressure drops, sympathetic nerves to the heart release norepinephrine, which promotes calcium uptake by heart muscle and acts on beta receptors of the heart to increase the strength and rate of heartbeat. Sympathetic nerves also release norepinephrine to the alpha receptors of the arterioles, causing them to contract. All of these effects increase blood pressure. The parasympathetic branch sends the vagus nerve to the heart, where it releases acetylcholine, causing the heart to beat more slowly, and with less force.
The kidneys can influence blood pressure by (1) excreting more sodium and water (lowering blood volume, and hence, lowering blood pressure) and (2) secreting the enzyme renin which produces angiotension I in the bloodstream. When angiotension I reaches the lungs, Angiotension Converting Enzyme (ACE) converts angiotensin I to angiotension II, which rapidly and powerfully constricts the arterioles, raising blood pressure.
Blood pressure is measured by two values: the highest pressure, when the heart is pumping or Squeezing (Systolic), and the lowest pressure, when the heart is relaxing or Dilating (Diastolic). A pressure of 140 mmHg is the amount of force necessary to raise a column of Mercury (Hg) 140 millimetres. The same amount of pressure would raise a column of water nearly 2 metres -- the heaviness of mercury makes it a more convenient measuring standard. In North America, Systolic/Diastolic pressure of 120/80 is considered "normal", although natives of New Guinea typically have a diastolic blood pressure of 60 mmHg -- and an extremely low incidence of stroke.
The following table indicates the hazards of high blood pressure:
Sys/Dia | MEN (age) | WOMEN (age)
| 35 55 | 35 55
-------------------------------------------------------------
130/90 | 4 years 1 year | 2 years 1 year
140/95 | 9 years 4 years | 5 years 3 years
150/100 | 17 years 6 year | 9 years 4 years
People with hypertension are 2-3 times more likely to have a heart attack than those with normal blood pressure. 45% of people with high blood pressure are unaware that they have it. Of those who are aware, fewer than half are being treated. People with uncontrolled high blood pressure are 7 times more likely to have a stroke than people with controlled high blood pressure. Hypertension is the major risk factor for stroke. 25% of people currently undergoing kidney dialysis can blame high blood pressure for their kidney damage. High blood pressure also damages many other organs.
75% of overweight (overfat) people with hypertension who lost 20 pounds or more achieved normal blood pressure -- besides reducing their blood LDL and elevating their blood HDL-cholesterol. Will-power to resist the temptations of hunger is at least as important in losing weight as the will-power to exercise. Dieting should only be undertaken as a permanent life-style change because "yo-yo dieting" is associated with an increased incidence of heart attacks.
VII. STRESS
Twenty years ago 60% of heart attack victims blamed their attack on stress. It is more socially acceptable to blame stress (and it wins more sympathy) than to admit to one's eating and smoking habits. Large scale studies of high-level executives have not shown an increased incidence of heart disease. Prospective studies have failed to show that such major life events as "death of spouse", "divorce" or "fired from work" are predictors of heart disease.
Nonetheless, people with hypertension show greater blood pressure increases in response to stress than do people with normal blood pressure. Stress must be interpreted as a subjective response, rather than defined in terms of external events. Stress-prone individuals tend to feel like alienated, helpless victims with little purpose in life, a sense of meaninglessness and little belief in their ability to change situations. This image contrasts sharply with that of the supposed stress-prone hard-driving, purposeful executive.
Relaxation and meditation can be learned and can lower blood pressure. People focusing conscious attention on their muscle groups can learn to relax them -- and people focusing conscious attention on their psychological straining (in meditation) can learn to relax that too. Relaxation techniques have been shown to lower systolic pressure by 11 mmHg and diastolic pressure by 7 mmHg. Even animals can be trained to lower blood pressure by use of biofeedback and rewards.
Although about 20% of the general population shows increased blood pressure with increased salt, the majority of persons with hypertension show a direct relationship between salt intake and blood pressure. More precisely, sodium from all sources (salt, MonoSodium Glutamate [MSG], baking soda, antacids, etc.) increases blood pressure in about 60% of hypertensive persons. The people of northern Japan, with a high-sodium diet (which included soy sauce, miso soup and pickled vegetables) had a 60% incidence of hypertension (the major cause of death was stoke) until a community-wide campaign taught people to alter their eating habits.
Since most North Americans get 20 times more sodium in their diet than they need, limiting sodium intake is not likely to hurt. In the average diet, 77% of sodium comes from processed foods, 12% from meat&vegetables, 6% from table salt and 5% from cooking salt. A diet low in potassium or calcium may affect blood pressure as adversely as a high sodium diet. A banana or an orange provide as much potassium as a third of a cup of raisins -- for half the calories. Tomatoes are also high in potassium, and a tomato can give approximately the same potassium as a banana or orange -- for half the calories.
VIII. CHOLESTEROL
Since the blood is 80% water, fats will not dissolve in blood. Therefore, fats need to be attached to carrier molecules to travel through the bloodstream. The principle carrier molecules for fat are albumin, chylomicrons, Very Low Density Lipoprotein (VLDL), Low Density Lipoprotein (LDL) and High Density Lipoprotein (HDL). Free Fatty Acids (FFAs) are attached to albumin, whereas triglycerides are mainly transported by chylomicrons and VLDL. Cholesterol and phospholipid are primarily transported by LDL and HDL.
Free Fatty Acids are a major source of energy for many organs, including the heart. Triglycerides are hydrolyzed into FFAs and glycerol by the enzyme lipase, which is found both inside cells and on the surface of the endothelial cells of capillaries. Phospholipid is an essential constituent of cell membranes. Cholesterol is also an essential constituent of cell membranes, particularly in the nervous system. As well, cholesterol is the principal precursor of cortisone and sex hormones. Of the cholesterol in the body, 93% is in cells and only 7% is in plasma.
Cholesterol is supplied to cells primarily by the attachment of LDL to specific LDL receptors on cell membranes. The Pima Indians of Nevada have diets high in fried foods -- and have one of the highest obesity rates in the world -- yet the high level of LDL receptors on their cells leaves them with a heart attack rate which is only one-quarter the American national average. In the mid-1980s it was established that the condition known as familial hypercholesterolemia (seen in less than 1% of the population) is the result of a defect in the gene responsible for the LDL receptor. Thyroid hormone lowers blood cholesterol by increasing the number of LDL receptors on cells. For most people, atherosclerosis due to excessive LDL-cholesterol in the blood is the result of a high level of dietary saturated fat resulting in high LDL-cholesterol production by the liver.
The primary function of HDL seems to be to remove excess cholesterol from the bloodstream. LDL can directly release cholesterol into arterial areas made porous by prostaglandins -- whereas HDL can scoop-up this loose cholesterol and return it to the liver. Thus, HDL deficiency can be as serious an atherosclerosis risk as LDL-cholesterol excess. A 1% reduction in blood cholesterol is generally associated with a 2% reduction in risk of coronary artery disease, within "normal" North American levels of blood cholesterol. A one mg/dl (0.26 mmol/Litre) increase in blood HDL reduces the risk of coronary artery disease by 2 to 3 percent.
Estrogen produced by the ovaries (estradiol) increases HDL and reduces LDL, probably by increasing the number of LDL receptors in the liver (removing LDL from the blood). Estradiol is believed to be the main reason why pre-menopausal women have such a lower incidence of heart disease than men. Men given estrogen therapy had an increase in coronary disease mortality. Birth control pills used in the 1980s increased the incidence of heart disease due to the anti-estrogen effect of synthetic progestin used. Newer synthetic progestins seem to have eliminated this problem.
Hormone Replacement Therapy (HRT) with estrogen reduces some of the discomfort associated with the onset of menopause (hot flashes, vaginal drying & thinning and urinary tract infections), but was shown in the 1970s to increase the risk of endometrial (lining of the uterus) cancer by 6-8 times. In 2002 a large-scale study was halted due to mounting evidence that HRT combining estrogen & progestin in women with a uterus (no hysterectomy) increased strokes 41%, heart attacks 29% and breast cancer 26%, while reducing colorectal cancer 37% and hip fractures 33% [JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION 288(3):321 (2002)].
IX. DIET
Most cholesterol in the blood is manufactured in the liver. If dietary cholesterol is too low, the liver manufactures more, and if dietary cholesterol is too high, the liver manufactures less. But the compensation is not complete, and dietary cholesterol does influence levels of cholesterol in the blood. Cholesterol is found in the tissue of animals, not plants -- specifically it is found in the muscle portion of meat, not in the fat. Egg yolks and organ meats have about the highest cholesterol content of any foods.
Saturated fats and artificially hydrogenated polyunsaturated fats raise blood cholesterol far more dramatically than cholesterol itself -- by increasing the manufacture of LDL-cholesterol in the liver. Animal fat (especially red meat and butter) and tropical oils (palm, coconut and chocolate) have the most saturated fat. Polyunsaturated fat lowers both LDL and HDL blood cholesterol, whereas monosaturated fat lowers LDL without lowering HDL cholesterol. Considering the potential damage due to free-radical oxidation by polyunsaturated fat, monosaturated fat becomes by far the most desirable option -- although reduction of all fat is probably the best option of all. Olive oil is 80% monosaturated fat and canola oil is 65% monosaturated.
Because LDL-cholesterol oxidation increases atherosclerosis formation, daily doses of the antioxidants Vitamin C, Vitamin E and beta-carotene reduces heart disease risk. In a survey of nearly 90,000 female nurses, those in the upper fifth with respect to Vitamin E intake had 2/3 the risk of major coronary disease as those in the lower fifth. A similar study of nearly 40,000 male health professionals showed those consuming over 60 IU of Vitamin E daily had less than 2/3 the risk of coronary disease as those consuming less than 7.5 IU daily [THE NEW ENGLAND JOURNAL OF MEDICINE 328:1444-1449 & 1450-1456 (1993)]. Vitamin C helps to regenerate Vitamin E. Beta-carotene was shown to increase the risk of heart disease in a controversial study involving smokers, but for non-smokers the evidence is less ambiguously in favor of reduced risk.
Animals fed fat-free diets display deficiency-disease symptoms that are completely eliminated by feeding them small quanitities of the essential fatty acids: linolenic, linoleic and arachidonic acid, all of which are 20-carbon-length polyunsaturated fatty acids. These are probably essential for health by being precursors of the 20-carbon-length eicosanoids (local hormomes): prostaglandins, prostacyclin, thromboxanes, lipoxins and leukotrienes. There is no justification for claims that 20%, 10% or even 5% of total calories need to come from fat for good nutrition. Fats produce 9 calories per gram, whereas proteins and carbohydrates only produce 4 calories per gram (a paperclip weighs about one gram).
Soluble fiber has been shown to lower blood cholesterol. The pectin in apples, pears, oranges, grapefruit and bananas is soluble fiber; as is the glucan in oat bran, peas, beans and whole wheat spaghetti; and as is the psyllium in the laxative Metamucil. Over a six week period, adults with high blood cholesterol showed a 16% drop in LDL-cholesterol with 57 grams of oat bran daily, and an 11.5% drop with 85 grams of oatmeal daily. One teaspoonful of Metamucil once or twice daily has been shown to reduce cholesterol 5%.
The Omega-3 fatty acids lower blood triglycerides, but their main benefit for preventing heart disease by being a precursor of prostaglandin, which inhibits platelet aggregation and dilates blood vessels. Although these fatty acids are present in fish, the richest source is linseed (flaxseed) oil, which is 55% linoleic acid. Nonetheless, the advantages of reduced clotting for heart disease may be undermined by the dangers of excessive bleeding -- especially for people at risk of cerebral hemorrhage. Moreover, omega-3 oils in large doses depress the immune system and have been associated with scarring of heart muscle in animal studies. The main advantage gained by following the recommendation to eat fish several times weekly may be that it reduces the consumption of animal meat. Vegetarianism may be more beneficial.
(For more details about essential fatty acid to prevent arrhythmia and heart disease my essay Fats You Need -- Essential Fatty Acids .)
During World War I severe food shortages led the Danish government to stop meat consumption for a full year. Mortality rate from disease dropped 34% during that year. The same experience was repeated in Norway during World War II -- and disease mortality returned to pre-war levels when meat was available again. The world's largest culture of people with long lifespan is the Hunzas, who are almost entirely vegetarian. In 1964, heart specialist Dr. Paul Dudley White (who treated Eisenhower's heart attack) traveled to Kashmir to study the Hunzas. He found no trace of coronary heart disease even in the 25 men he studied who were over 90. A study of 24,000 people at Loma Linda University showed lacto-ovo vegetarians to have one third the heart disease mortality and pure vegetarians to have one tenth the heart disease death rate of meat-eaters.
A vegetarian diet not only dramatically reduces fat and cholesterol intake, it reduces the amount of concentrated pesticide and chemical toxin found in high food-chain organisms. The World Health Organization has established that an adult requires only 5% of total calories in the form of protein (the same proportion found in human mother's milk -- cow's milk is 15%). Nearly all vegetables, legumes, grains, nuts and even fruit has at least that much protein (a banana's protein is 5% of total calories -- spinach and broccoli have protein nearly 50% of total calories). Most of the original 1971 edition of the book DIET FOR A SMALL PLANET dealt with combining protein, but the 1981 edition was mostly re-written to combat the misimpression that without animal protein one must pay close attention to ensure sufficient percentages of amino acids. Worry that vegetarian diets contain insufficient iron is also mistaken -- spinach, cucumber, lettuce, strawberries and lima beans all have several times the iron per calorie as does lean ground beef. Nonetheless, even the ardent vegetarian John Robbins advocates that vegetarians take Vitamin B12 supplement. (Meat, incidently, is the most common cause of airway obstruction and choking in adults.)
X. COFFEE AND ALCOHOL
Boiled coffee has been shown to increase blood cholesterol by 10%, whereas filtered-coffee has no such effect. The difference is due to "coffee fat" in the former, which in purified form can increase blood cholesterol dramatically. A study of 1,130 male medical students showed a 2-3 fold greater risk of coronary artery disease among those who drank more than 5 cups of coffee per day (the study doesn't reveal whether the coffee was boiled or filtered). But the increased cardiovascular risk associated with high coffee consumption applied only to nonsmokers. Caffeine is known to promote atrial fibrillation in some persons.
Those who have 2 to 4 alcoholic drinks daily have twice the incidence of hypertension, and those who have more than 4 drinks per day have more than triple the incidence of hypertension. [A drink is defined as 15 millilitres (ml) of absolute alcohol, equivalent to a 50 ml shot of 80 proof liquor, a 150 ml glass of 12% wine or a 355 ml can of 4.5% beer.] Fewer than two drinks daily has not been implicated in heart disease, although the Honolulu Heart Study showed double the incidence of stroke for one drink daily and triple the incidence for three or more drinks daily. Moderate amounts of alcohol elevate HDL-cholesterol and lower LDL-cholesterol in animals. Some studies have shown that light drinkers have a 40-50% lower risk of coronary artery disease than teetotalers. (Former alcoholics are often counted as "teetotalers".)
Alcohol, however, has "side effects", aside from the possible stroke risk. Disruption of the hardware of the brain may mainly be temporary, but some lasting effects may be possible. One drink provides 120 empty calories with virtually no nutritional value. Moreover, it stimulates the appetite while dulling the better judgement and self-control that could prevent overeating or a relapse into smoking. Niacin produces a more dramatic increase in HDL and decrease in LDL, without these side-effects.
XI. EXERCISE
A study of 6,000 San Francisco longshoreman showed that light workers had 2.5 times as many fatal heart attacks and 3 times the incidence of sudden cardiac death as moderate or heavy workers. Another study divided 4,000 healthy men aged 30 to 69 into 4 quartiles by fitness. In the subsequent 8 years, the lowest quartile had 8.5 times the cardiovascular death rate as the highest quartile, even after smoking, cholesterol and blood pressure were factored-out. In Framingham, the 16% of males and 21% of females who lived the most sedentary lives had 3.5 time the rate of coronary artery disease.
Other studies have shown that at least 3 weekly 30-minute sessions of aerobic exercise results in blood pressure drops averaging 6 mmHg for diastolic and 11 mmHg for systolic pressure. Weight lifting and isometric exercise do not qualify. Aerobic exercise involves rhythmic movement of large muscle groups and should be vigorous enough that it corresponds to at least 50% of a person's maximum ability to bring oxygen to muscle. It should not be so strenuous that it reduces oxygen exchange. Such exercise increases the number of collateral vessels in the heart and increases blood HDL.
When a person is at rest or engaged in light activity, muscles primarily utilize Free Fatty Acids (FFAs) as their energy source. This is an aerobic process (ie, it uses oxygen). The term "aerobic" also refers to aerobic glycolysis (glucose/glycogen metabolism) as opposed to anaerobic glycolysis. Extremely intense and vigorous exertion may place demands on muscle that are in excess of those which could be met with available oxygen. Nature has provided the mechanism of anaerobic glycolysis as a source of spurts of energy that are potentially of survival value in critical "fight or flight" situations. In a 100-metre dash that takes 10 seconds, 85% of the energy is derived anaerobically, a 2-mile race lasting 10 minutes would use 20% anaerobic energy, and a 60-minute long-distance race would use 5% anaerobic energy (95% aerobic energy).
Anaerobic exertion is intense and short-lived. It produces lactic acid which inhibits enzymes, making further exertion difficult. A person will be "winded" until the "oxygen debt" is repaid. Anaerobic exertion is not particularly beneficial for the cardiovascular system. Sustained, moderately intense exertion that allows for high oxygen exchange is very beneficial. Aerobic exercise is also of value in eliminating fat, because after 10 minutes glycogen stores begin to drop, and after 30 minutes most of the muscle fuel comes from breakdown of triglycerides from fat stores. It is probably good to take anti-oxidants prior to aerobic exercise, to reduce resulting free-radicals.
Care should be taken not to begin an exercise program that involves excessive exertion which the subject is not used-to. A heart attack due to unusual strain defeats the purpose. Five minutes of initial stretching is important to avoid pulling muscles. A warm-up period avoids initial strain and a cool-down period is even more important. Stopping exercising too suddenly can dramatically reduce venous return of blood to the heart (because muscular contractions propel blood in the veins), which can provoke a heart attack if the heart's own oxygen needs are not being met.
XII. ASPIRIN
The main effect of aspirin is to block production of the short-acting "local hormone" thromboxane -- resulting in reduced platelet aggregation (clotting) and reduced artery constriction. This is seemingly of value to prevent heart attacks, although it does not seem advisable for those at risk of hemorrhagic stroke. In fact, by aspirin use risk of death has been reduced 15% among survivors of heart attack, stroke, TIA and unstable angina. The benefit of aspirin for others is debatable.
A well-publicized study of 22,000 American male physicians taking 325 mg of aspirin on alternate days showed 44% fewer heart attacks, but no fewer cardiac arrests or total cardiovascular deaths. A similar study with British male physicians taking 500 mg aspirin daily failed to show reduction in heart attacks. Both studies showed higher incidence of hemorrhagic stroke and bleeding ulcers with aspirin.
XIII. DIAGNOSTIC TOOLS
Few people need to wait until a heart attack to discover that they have heart problems. Many means of examining the heart are available, and if Jerry Leaf had been willing to have himself checked-out for cardiovascular health, chances are very good that preventative measures could have been taken.
ElectroCardioGraphy (ECG) displays the "P-QRS-T" waves of heart rhythm. ECG tests are especially effective when done as part of an exercise stress test, where the ECG is measured while the patient walks at a fast pace on a treadmill. An exercise stress test correctly identifies the presence of coronary artery disease 70% of the time, and correctly identifies the absence of coronary artery disease 90% of the time. An exercise stress test can also reveal electrical instability in heart rhythms.
Chest X-rays can reveal the calcium deposits of advanced coronary arteriosclerosis. In radionuclide scanning, a small amount of radioactive thallium is injected so that the pumping efficiency of the heart can be visualized with a Gamma camera. Echocardiography uses ultrasound waves reflected (echoed) from the heart to examine functioning heart structures, particularly the valves. Computed Tomography (CT, or "CAT scanning") uses an X-ray machine that is rapidly rotated around someone's body to produce computer-constructed images of the heart or brain in "slices" (like sliced bread). Magnetic Resonance Imaging (MRI) uses magnetic fields and radiowaves rather than X-rays to produce similar results as CAT scanning. Positron Emission Tomography (PET) visualizes tissue metabolism, but it is still too expensive to be used in routine medical examinations. Direct assessments of the heart can be made by inserting catheters.
People often have myocardial infarctions that involve such small portions of the heart that they experience no symptoms and are completely unaware that it happened. Nonetheless, such an event is often preliminary to a more serious heart attack. Damaged heart cells leak enzymes into the bloodstream, such as Creatine PhosphoKinase (CPK), Lactic DeHydrogenase (LDH) and Serum Glutamic Oxaloacetic Transaminase (SGOT). Blood Urea Nitrogen (BUN) and creatinine often indicate kidney damage due to high blood pressure. Blood tests often indicate problems before changes are apparent on an electrocardiogram.
XIV. MEDICAL INTERVENTION
Drug therapy can be used to lower cholesterol, reduce hypertension and prevent clotting. For patients with serious blockage of the left main coronary artery, bypass surgery will increase expected 50% survival time from 5 to 10 years (which can buy time for advances in artificial hearts or other alternatives). Coronary angioplasty uses a catheter with a balloon tip to mechanically enlarge coronary arteries. An atherectomy catheter uses a rotating disk to shave-off atheromas. Catheters with laser tips vaporize plaque which dissolves in the bloodstream and is eliminated as natural body waste.
Pacemakers can be implanted on hearts that do not have a well-controlled natural electrical rhythm. External defibrillators can be worn which detect heart stoppage or electrical irregularity and apply a shock to restart the heart.
Fibrinolytics administered within a few hours of a heart attack will dissolve clots in the artery. Streptokinase and tissue plasminogen activator (t-PA) are most widely used for this purpose. Concomitant injection of heparin seems to enhance the effectiveness of these agents.
XV. CRITICAL CARE UNITS (CCUs) AND CRYONICS HOSPICES
In Coronary Care Units (CCUs), patients are kept on continuous 24-hour electrocardiographic monitoring, and computers automatically sound the alarm when serious irregularities appear. David Pizer, of the Venturists, has long had dreams of a hospice where terminally ill cryonics patients could receive continuous nursing care -- as well as rapid declaration of death and application of cryonic procedures (when needed). The July 1994 issue of VENTURIST MONTHLY NEWS announced that significant progress is expected in the coming year towards the creation of a "Ventureville" facility of this type.
Every year of life is not only precious, but it improves the chances of extending life even more or, if necessary, improving the conditions of deanimation.
(See also my essay Sudden Cardiovascular Death )
XVI. REFERENCES
(in descending order of usefulness)
- TAKE HEART! Terence Kavanaugh 1992
- MAYO CLINIC HEART BOOK Michael D. McGoon, Ed. 1993
- REVIEW OF MEDICAL PHYSIOLOGY (16th Ed.) William F. Ganong 1993
- BYPASS J.L. Halperin and R. Levine 1987
- HYPERTENSION Mike & Nancy Samuels 1991
- HOW TO PREVENT A STROKE Peggy Jo Donahue 1989
- DIET FOR A NEW AMERICA John Robbins 1987
- HIGH BLOOD PRESSURE Neil B. Shulman, et.al. 1993
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