• Introduction
• What is a Angina?
• Known causes
• Symptoms
• Prevention
• Diagnosis
• Conventional treatment 

Introduction

Coronary artery disease (CAD) and angina are part and parcel of coronary heart disease (CHD) - the most common cause of death in the western world and said to account for nearly 50% of all deaths in the U.K. Contrary to popular belief, arterial degeneration does not only affect elderly patients. Of 3,000 US soldiers under 30 years of age who were killed in the Korean war, over 50% showed damage to their coronary arteries and a further 25% showed 'marked changes'.

CAD refers to those syndromes caused by blockage to the flow of blood in those arteries supplying the heart muscle itself. Like any other organ, the heart requires a steady flow of oxygen and nutrients to provide energy for movement, and to maintain the delicate balance of chemicals which allow for the careful electrical rhythm control of the heart beat. Unlike some other organs, the heart can survive only a matter of minutes without these nutrients, and the rest of the body can survive only minutes without the heart!

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What is Angina?

Angina is the medical term for the intense chest pain and sense of suffocation caused by insufficient blood supply to the heart. The crushing pain represents the area of the heart which is trying to function with inadequate supply from its coronary artery, just as an overutilised muscle in the arm or leg might hurt under similar circumstances.

It usually occurs on exertion and if the stress is relieved, recovery takes place with no permanent damage to the heart as the previous level of circulation to that area of heart is again adequate. Recovery, in this instance, takes place with no permanent loss of muscle in the heart. However, if the stress continues, or if the blockage is so critical that even at rest the blockage is too great to stand, the patient experiences further symptoms - progressive pain, profuse sweating, shortness of breath, palpitations, and finally collapse. As the affected area of heart muscle finally dies, a heart attack or myocardial infarction is said to occur.

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Known causes

There are various possible causes for blocked coronary arteries but by far the most common cause is the deposition of plaques of cholesterol, platelets and other substances within the arterial walls. Sometimes the build-up is very gradual, but in other cases the build-up is suddenly increased as a chunk of matter breaks off and suddenly blocks the already narrowed opening.

There are several factors which may influence the build-up of these plaques. These include:-

Since the late 60's, the incidence and mortality rate of coronary disease has been rapidly declining. The reasons seem to be related to changes in diet, blood pressure control, and physical exercise. 

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Symptoms

As plaques begin to clog the coronary arteries, several things may occur. In some, no symptoms are noted until a fatal heart attack. In others, no symptoms are noted at rest, but with exercise or other stress, a dull aching pain is noted in the chest, neck, jaw, upper abdomen, arm, or back. Typically, this subsides with rest.

Effects of a Heart Attack - The outcome of a heart attack depends on the extent, location and size of the area of heart involved. Even a "small" one, if located in a critical area of the heart, or if it sets off an unstable rhythm (see cardiac arrhythmia section) can be fatal. Large heart attacks destroy so much muscle that the pumping action is inadequate and often results in congestive heart failure. Many heart attacks are intermediate, and various degrees of complications may be noted. In many of these cases, complete or near complete recovery is common.

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Prevention

This is simply a matter of eliminating the primary risk factors listed above. Of particular significance is cigarette smoking, alcohol, stress and high cholesterol foods all of which should be avoided (see Diet, Nutrition & Lifestyle section below). 

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Diagnosis

It has been estimated that at least two thirds of patients with heart attacks have warning symptoms of angina and chest pain, marked fatigue, or other problems in the month before the event. Often the symptoms are typical as described above but sometimes they may be atypical or subtle. It is important to see a medical practitioner if you are at all concerned about unexplained symptoms relating to the chest, neck, abdominal, back, jaw, or arm.

Diagnosis is often confirmed with the aid of an electrocardiogram (EKG) , however, even if this shows normal, both angina and heart attack in the early stages cannot be ruled out. Blood tests may reveal chemical changes of a heart attack, but sometimes intense observation in the cardiac unit with repeated blood tests and EKG's is required to confirm the diagnosis.

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Conventional treatment

Treatment of CAD and angina is mainly in the form of drugs and/or surgery. The choices are complicated, and depend largely on individual factors, as well as regional health authority resources and preferences. General comments on the major options are included in this section, although exceptions are common.

Drug therapy: - Medications are often prescribed to control the symptoms. The oldest and most common agents are the nitrates, derivatives of nitroglycerine. They include nitroglycerine, isosorbide, and similar agents. Newer forms include long acting oral agents, plus skin patches which release a small amount through the skin into the bloodstream over a full day. They act by reducing the burden of blood returning to the heart from the veins and also by dilating the coronary arteries themselves. Nitrates are considered by many to be the mainstay of medical therapy for angina, and are used both for treatment of symptoms as well as prevention of anticipated symptoms. They are considered to be effective for relief and prevention of angina, and sometimes for limiting the size of a heart attack. However, there are side effects associated with these drugs including headaches, dizziness, postural hypotension and tachycardia (1).

The second group of drugs are called "beta blockers" for their ability to block the activity of the beta receptors of the nervous system. The beta receptors cause blood pressure elevation, rapid heart rate, and forceful heart contractions. When these actions are decreased, the heart needs less blood, and thus angina and even the extent of a heart attack may be reduced. Again, these drugs have known possible side effects including gastro-intestinal disturbances and incredibly, heart failure! (2). 

The latest group of drugs for coronary disease is called the calcium channel blockers. Calcium channels refer to the areas of the membranes of heart and other cells where calcium flows in and out, reacting with other chemicals to modulate the force and rate of contractions. In the heart, they can reduce the force and rate of contractions and electrical excitability, thereby having a calming effect on the heart. These drugs also have known side effects including oedema, liver and kidney damage, headache, nausea and rashes (3). 

Surgery: - Coronary bypass surgery has become commonplace. The procedure consists of transplanting veins from the leg (or vessels from elsewhere in the chest) to the blocked area, bypassing or "jumping over" the obstructed vessels. As many as four or five vessels may be bypassed, thus restoring flow to the area previously blocked off. During the operation, the heart is temporarily replaced by the "heart-lung" machine. 

There is major controversy surrounding the benefits and selection of patients for surgery. However, it is clear that unless surgery is contemplated or the diagnosis is in question, most patients do not require catheterization or surgery. Furthermore, surgery as a life-prolonging measure is questionable for most patients, and no study has been done comparing surgery with medical management using the newer drugs. Experts who reviewed bypass surgery over a 15 year period concluded that, in most cases, the operation has not been shown to save lives. In fact, they found that, quite the contrary, there is a 15% (or greater) risk of brain damage following coronary bypass surgery(4).