The American Heart Association describes the six major forms of CVD as coronary heart disease, hypertension, stroke, congenital heart disease, rheumatic heart disease, and congestive heart failure. A person may have just one of these diseases or a combination of them at the same time. Each form exists in varying degrees of severity. All are capable of causing secondary damage to other body organs systems.
Coronary Heart Disease
This form of CVD, also known as coronary artery disease, involves damage to the vessels that supply blood to the heart muscle. The bulk of this blood is supplied by the coronary arteries. Any damage to these important vessels can cause a reduction of blood (and its vital oxygen and nutrients) to specific areas of heart muscle. The ultimate result of inadequate blood supply is a heart attack.
Atherosclerosis
The principle cause for the development of coronary heart disease is atherosclerosis. Atherosclerosis produces a narrowing of the coronary arteries. This narrowing stems from the long-term buildup of fatty deposits, called plaque, on the inner walls of the arteries. This buildup reduces the blood supply to the specific portions of the heart. Some arteries of the heart can become so blocked (concluded) that all blood supply is stopped. Heart muscle tissue begins to die when it is deprived of oxygen and nutrients. This damage is known as myocardial infarction. In lay terms, this event is called a heart attack.
Cholesterol and Lipoproteins For many years, scientists have known that atherosclerosis is a complicated disease that has many causes. Some of these causes are not well understood, but others are clearly understood. Cholesterol, a soft, fatlike material, is manufactured in the liver and small intestine and is necessary in the formation of sex hormones, cell membranes, bile salts, and nerve fibers. Elevated levels of serum cholesterol (200 mg/dl or more for young adults age 20 and older, and 1709 mg/dl or more for young people below age 20) are associated with an increased risk for developing atherosclerosis.
About half of American adults age 20 and older exceed the “borderline high” 200 mg/dl cholesterol level. It is estimated that nearly 40% of American youth age 19 and below have “borderline high” cholesterol levels of 170n mg/dl and above. About one out of five American adults has a “high” blood cholesterol level, that is, 240 mg/dl or greater.
Initially, most people can help lower their serum cholesterol level by adopting three dietary changes: lowering their intake of saturated fats, lowering their intake of dietary cholesterol, and lowering their caloric intake to a level that does not exceed body requirements. The aim is to reduce excess fat, cholesterol, and calories in the diet while promoting sound nutrition. By carefully following such a diet plan, people with high serum cholesterol levels may be able to reduce their cholesterol levels by 30 to 55 mg/dl. However, dietary changes do not affect people equally; some will experience greater reductions than others. Some will not respond at all to dietary changes and may need to take cholesterol-lowering medications and increaser their physical activity.
Cholesterol is attached to structures called lipoproteins. Lipoproteins are particles that circulate in the blood and transport lipids (including cholesterol). Two major classes of lipoproteins exist: low-density lipoproteins (LDLs) and high-density lipoproteins (HDLs). A person’s total cholesterol level is chiefly determined by the amount of the LDLs and HDLs in a measured sample of blood. For example, a person’s total cholesterol level of 200 mg/dl could be represented by an LDL level of 130 and an HDL level of 40, or an LDL level of 120 and an HDL level of 60. (Note that other lipoproteins do exist and carry some of the cholesterol in the blood.)
After much scientific study, it has been determined that high levels of LDL are a significant promoter of atherosclerosis. This makes sense because LDLs carry the greatest percentage of cholesterol in the bloodstream. LDLs are more likely to deposit excess cholesterol into the artery walls. This contributes to plaque formation.
For this reason, LDLs are often called the “bad cholesterol.” High LDL Levels are determined partially by inheritance, but they are also clearly associated with smoking, poor dietary patterns, obesity, and lack of exercise.
On the other hand, high levels of HDLs are related to a decrease in the development of atherosclerosis. HDLs are thought to transport cholesterol out of the bloodstream. Thus HDLs have been called the “good cholesterol.” Certain lifestyle alterations, such as quitting smoking, reducing obesity, increasing physical activity, and replacing saturated fats with monosaturated fats, help many people increase their level of HDLs.
Reducing total serum cholesterol levels is a significant step in reducing the risk of death from coronary heart disease. For people with elevated cholesterol levels, a 1% reduction in serum cholesterol level yields about a 2% reduction in the risk of death from heart disease. Thus a 10% to 15% cholesterol reduction can reduce risk by 20% to 30%.
Angina Pectoris When coronary arteries become narrowed chest pain, or angina pectoris,is often felt. This pain results from a reduced supply of oxygen to heart muscle tissue. Usually, angina is felt when the coronary artery disease patient becomes stressed or exercises too strenuously. Angina reportedly can range from a feeling of mild indigestion to a severe viselike pressure in the chest. The pain may extend from the center of the chest to the arms and even up to the jaw. Generally, the more severe the blockage, the more pain is felt.
Some cardiac patients relieve angina with the drug nitroglycerin, a powerful blood vessel dilator. This prescription drug, available in slow-release transdermal (through the skin) patches or small pills that are placed under the patient’s tongue, causes a major reduction in the workload of the heart muscle. Other cardiac patients may be prescribed drugs such as calcium channel blockers or beta blockers.
Emergency Response to Heart Crises
Heart attacks need to be fatal. The consequences of any heart attack depend on the location of the damage to the heart, the extent to which heart muscle is damage, and the speed with which adequate circulation is restored. Injury to the ventricles may very well prove fatal unless medical countermeasures are immediately undertaken. The recognition of a heart attack is critically important.
Cardiopulmonary resuscitation (CPR) is one of the most important immediate countermeasures that trained people can use when confronted with a victim of heart attack. Programs sponsored by the American Red Cross and the American Heart Association teach people how to recognize, evaluate, and manage heart attack emergencies. CPR trainees are taught how to restore breathing and circulation in persons requiring emergency care. Frequently, colleges offer CPR training through courses in various departments. With revised CPR procedures in place in 2001, we encourage students to take a new course and become certified. Additionally, members of the public are encouraged to obtain training in the use of automated external defibrillators (AED). These devises are now found in most public buildings and can markedly improve the chances of resuscitating a victim.
Diagnosis and Coronary Repair
Once a person’s vital signs have stabilized, further diagnostic examinations can reveal the type and extent of damage to heart muscle. Initially an ECG might be taken, which may be able to identify if areas of ischemia (insufficient blood flow) or damage has occurred to the heart muscle. Another test which may be used is echocardiography. This procedure can also detect ischemia. The diagnostic ability of both of these tests is improved if used in conjunction with exercise (i.e., stress ECG or stress echocardiography). This test analyses the electrical activity of the heart. Heart catheterization, also called coronary arteriography, is a minor surgical procedure that starts with placement of a thin plastic tube into an arm or leg artery. This tube, called a catheter, is guided through the artery until it reaches the coronary circulation, where a radiopaque dye is then released. X-ray films called angiograms record the process of the dye through the coronary arteries so that areas of blockage can be easily identified.
Once the extent of the damage is identified, a physician or team of physicians can decide on a medical course of action. Currently popular is an extensive form of surgery called coronary artery bypass surgery. An estimated 516,000 patients had bypass surgeries in 2001. The purpose of such surgery is to detour (bypass) areas of coronary artery obstruction by usually using a section of an artery from the patient’s chest (the internal mammary artery) and grafting it from the aorta to a location just beyond the area of obstruction. Multiple areas of obstruction result in double, triple, or quadruple bypasses.
Angioplasty Angioplast, an alternative to bypass surgery, involves the surgical insertion of a doughnut-shaped “balloon” directly into the narrowed coronary artery. When the balloon is inflated, plaque and fatty deposits are compressed against the artery walls, widening the space through which blood flows. The balloon usually remains in the artery for less than 1 minute. Renarrowing of the artery will occur in about one quarter of angioplasty patients. Balloon angioplasty can be used for block-ages in the heart, kidneys, arms, and legs. The decision whether to have angioplasty or bypass surgery can be a difficult one to make. Nearly 1,050,000 angioplasty procedures were performed in 2001.
The FDA approved a device for clearing heart and leg arteries. This devise is called a motorized scraper. Inserted through a leg artery and held in place by a tiny inflated balloon, this motor-driven cutter shaves off plaque deposits from inside the artery. A nose cone in the scraper unit stores the plaque until the device is removed.
