What is angina?
Angina is short for "angina pectoris," which in Latin means "pain of the chest." More specifically, angina is pain originating from the heart when it doesn't get enough blood flow.
How does angina occur? What causes it?
At different times, the heart has a varying need for blood flow and the oxygen it carries. The heart receives this blood flow through its own set of blood vessels called the coronary arteries. Normal coronary arteries can open up and the heart can pump itself more blood during times of increased need. Unfortunately, over time, these arteries can develop internal blockages that slow the flow of blood through them. When these blockages reach a certain degree — usually when the internal size of the artery is narrowed by about 70% or more — it becomes impossible for the heart to get enough blood during the times it needs more. These times of increased need include:
- During exercise
- When performing physical work
- After eating
- When experiencing emotional stress or a sudden increase in blood pressure
With the relatively decreased blood flow and oxygen, the heart muscle produces chemicals that cause the pain and other symptoms of angina. Stopping the exertion or work and placing nitroglycerine under the tongue helps restore the blood flow balance — symptoms are usually resolved in 5-10 minutes.
How and why do these blockages in the coronary arteries develop?
The coronary arteries start off, as do all arteries, with a smooth inner lining. Over time, material becomes imbedded in plaques, or deposits, under the inner lining. This process is called atherosclerosis, when it occurs in the coronary arteries it is called coronary artery disease (CAD) Plaques are a mixture of cholesterol, fatty acids, and scar tissue. Ongoing inflammation seems to be an active part of the process. Though CAD seems to be part of the natural aging process of the arteries, it develops at widely differing rates in different individuals, based on a variety of factors:
- High blood pressure
- Abnormal blood cholesterol levels (high LDL cholesterol and/or low HDL cholesterol)
- Male gender
- Eating increasing amounts of saturated fat and cholesterol (whether the blood cholesterol levels are abnormal or not)
- Being overweight
- Sedentary lifestyle
- Cocaine use
- High levels of certain chemicals in the blood, like homocysteine
Each of these factors causes damage to the arterial lining and/or causes plaques to develop more rapidly.
What are "hereditary factors"?
Though the chance of developing CAD and angina increases for everyone with increasing age, it seems that an increased chance of developing it earlier in life tends to "run in families." If someone in an individual's immediate family - a parent, brother, or sister — has had a heart attack or angina before age 50, then that individual has an increased risk of developing CAD at an earlier age. This hereditary effect is in addition to having high blood pressure, diabetes, or a high cholesterol level running in one's family.
Is chest pain the only symptom of angina?
Not entirely. While angina means literally "pain," the term is used to describe any of the symptoms that can result from decreased blood flow to the heart. For many people this includes some type of chest discomfort, either as the main symptom or one of a combination of symptoms. Some describe pressure or tightness in the chest rather than pain, per se. People may also experience any of a variety of symptoms, including:
- Sensation of indigestion or discomfort in the abdomen
- Breathing difficulty
- Excessive sweatiness
- Nausea or vomiting
- Pain, pressure, or numbness in the neck, jaw, upper or mid back, or arms.
- Symptoms unrelated to chest discomfort are referred to by doctors as "anginal equivalents."
Can someone ever be sure that chest pain is not angina?
This is a difficult question, but chest pain that occurs once or twice and is brief, lasting only a few seconds, is unlikely to be related to the heart or any other significant problem. However, people with a wide variety of chest sensations - for example, burning, tingling, "electrical feeling," sharp pain, dull pain, pain worse when moving the arms or neck or worse when swallowing or breathing — as well as those with the anginal equivalents described above, could be having angina, a heart attack, or another life-threatening problem. In short, the chest contains several vital organs and any recurring or prolonged abnormal feeling is a cause for concern. Seeing a doctor promptly is the best course of action. In many cases, this may mean calling an ambulance for transportation to the emergency department of the nearest hospital.
Is angina the same thing as a heart attack?
Angina is not the same as a heart attack, but the difference is only one of degree. CAD causes both conditions, but while angina is the result of the gradual development of partial blockages in the coronary arteries, a heart attack is caused by very sudden, total or near-total blockages in these vessels. Because CAD underlies both processes, those with angina are at increased risk for a heart attack, though about 50% of heart attacks occur in individuals who have had no prior angina or symptoms of heart disease.
Are there different degrees or severities of angina?
Yes. A stable pattern of symptoms to which a person has become accustomed over time is called stable angina. With stable angina, a particular level of activity — for example walking up three or more flights of stairs - may predictably bring on a person's symptoms. When he or she rests or takes a nitroglycerine tablet, the symptoms are relieved over a few minutes. There is no immediate need to treat stable angina (other than resting or using nitroglycerine when symptoms result), and patients with stable angina have been treated with medications only for many years. Increasingly, however, angioplasty or coronary bypass surgery on a non-urgent basis is being used to help reduce symptoms for those with stable angina, especially if angina occurs at a relatively low level of activity.
If the amount of coronary artery blockage increases, lesser levels of exertion can bring on angina, or symptoms may last longer, or take more time to resolve. When this progression happens over a matter of a few hours or days, or when a person experiences recurrent symptoms at rest, it is called unstable angina. Those patients with unstable angina are at high risk for heart attack and therefore require immediate treatment. This rapid progression of symptoms usually occurs because one of the coronary artery plaques or blockages "ruptures" or breaks through the inner artery lining. When the material in the plaque is exposed to the bloodstream, a clot rapidly forms, quickly reducing blood-flow and causing worsening symptoms. When the blockage is total or near total, a heart attack begins. Alternately, a person with long-term stable angina may gradually worsen over time, to the point of having unstable angina just on the basis of gradually worsening CAD.
In the first few days after a person experiences angina for the first time, it cannot be determined whether a person will have a stable pattern or will quickly develop an unstable one. For this reason, those with a new onset of angina, no matter how mild, are usually treated as though they have unstable angina.
There is another less common form of angina called "variant angina," "atypical angina" or "Prinzmetal's angina" (named for one of the doctors who first described it). It is caused by spasm of an area of a coronary artery. The symptoms are similar to those of the other forms of angina, but usually occur at rest and may occur in younger persons and those felt to be at low risk for CAD (though cigarette smoking is quite often associated with this form of angina, too). Nitroglycerine and other medications that relax the blood vessel spasm help relieve the problem. Though it sounds like unstable angina, the risk of heart attack is lower with variant angina because underlying rigid blood vessel blockage is not the problem and the spasm is reversible. Because they seem so similar in terms of symptoms, the definitive diagnosis of atypical angina often requires an angiogram or cardiac catheterization to look for underlying CAD. Sometimes patients with variant angina will also have underlying CAD that may or may not give them a different pattern of symptoms.
How is angina diagnosed and evaluated?
Angina is first suspected based on a person's symptoms - the more typical the symptoms, the easier it is to diagnose. Patients with neck or arm pain, dizziness, or nausea present more of a challenge for the patient and physician because these symptoms are linked to many other problems besides heart disease. In any case, once angina is suspected, several tests help to evaluate things further - including confirming the diagnosis and determining the severity of the underlying CAD, which will help to determine the optimal treatment. In each case, deciding which test is best depends on the level of suspicion for CAD and angina and the suspected severity of the underlying problem.
A first step is an electrocardiogram or ECG. When the heart is not getting enough blood, the electrical waveforms of the ECG can show characteristic changes from normal that may help make a diagnosis. The limitations of ECG are that heart problems other than CAD can cause changes in the waveforms, and that even when a person is having angina or a heart attack, the ECG may be completely normal. Timing is also important. If the ECG is done at a time when a person feels no symptoms and the blood flow is adequate, it may not reflect what happens when decreased blood flow occurs.
This last limitation is reduced when an ECG is done during exertion or exercise. This is the basis for an exercise treadmill test (ETT), sometimes called a "stress test." The exercise causes an increased need for blood that the diseased vessels cannot provide, and therefore the ECG may become abnormal. The patient may also experience angina symptoms during exercise. Unfortunately, the ETT is not perfect and, for a variety of reasons, may be incorrectly positive or negative up to 35% of the time.
The limitations of the ETT can be reduced, however, by adding an echocardiogram or radioisotopic imaging to the process. This is called a stress echocardiogram study ("stress echo") or stress imaging (usual radioisotopes include thallium 201 or technetium 99m). Using a sophisticated computer and monitor and a plastic probe and some gel on the chest, the echocardiogram can look directly at the movements of the heart with each beat. It has been shown that when the heart isn't getting enough blood, the walls of the heart move in a manner describes as dyssynchronous. There are several patterns of irregularity of varying severity. This "wall motion abnormality," as it is called, can happen before the ECG is abnormal and before a person develops chest pain or other angina symptoms. Though it provides increased accuracy for the diagnosis of CAD and angina, it, too, is not 100% accurate.
Radioisotopic imaging is accomplished when an isotope is injected through an IV line during a period of exercise. By comparing pictures of the heart (created by radiation emitted from the radioisotope) during and after exercise, areas of decreased blood flow or prior heart damage can be identified. Though it is more accurate, the stress thallium study takes more time than the other stress tests, is more expensive, and involves an IV and some radiation (though not much).
With any stress test, an adequate level of exercise is extremely important for the accuracy of the study. This is calculated based on the person's age, heart rate and blood pressure with exertion. Stress testing demonstrates what happens with exercise, and in the "recovery period" after exercise (this can be important as well). During this period, irregular heart rhythms or a slower than expected return to normal heart rate can indicate a poor prognosis.
If a person cannot exercise adequately — due to age, arthritis, poor conditioning, or lung problems, for example — then activity can be simulated by a continuous IV injection of a medication called dobutamine. This causes the heart rate and blood pressure to increase without having to exercise and is used mostly in conjunction with the stress echo. An alternative to dobutamine for the thallium study is a continuous injection of a medication called dipyridamole that causes unblocked coronary arteries to widen while those that have significant blockages cannot. The differences between the areas of the heart supplied by the blocked and unblocked vessels can then be seen on the thallium pictures.
The most accurate test or gold standard for the evaluation of CAD and angina is an angiogram or cardiac catheterization. This is, however, the most expensive and invasive of the tests and is therefore used only when absolutely necessary. An angiogram involves the use of a significant, though safe, amount of radiation (x-rays), and is the most difficult to perform and most risky of the tests addressed in this article. In trained hands, however, the risk of complications is less than 1-2%. The angiogram procedure involves threading a catheter, or thin plastic tube, from a blood vessel in the groin or in the arm up into the aorta, the major blood vessel going from the heart to the body. The openings for the coronary arteries are in this location and contrast dye is injected through the catheter into them. X-rays are used to show the arteries and any blockages. Laying out the pattern and extent of diseased vessels with an angiogram is necessary prior to angioplasty or bypass surgery.
A developing technology for evaluating some patients with CAD is magnetic resonance angiography, or MRA. By using the same MRI technology that's used more commonly to look at the brain, spine, or joints, some significant coronary artery blockages can be seen. There are limitations to this study, but it may be an alternative in some cases.
Another CAD test that has received getting media attention is the electron beam CT scan (EBCT). This type of "heart scan" is often offered in a shopping mall setting, either by itself or as part of a "total body scan." This technology uses some radiation, but is appealing because it does not involve needles, exercise, or apparent risk. It works by detecting tiny calcium deposits in the lining of the coronary arteries. In some situations, this has allowed people to know they have potentially significant CAD before they have symptoms. In other situations, there are calcium deposits but no significant narrowing of the arteries, and the abnormal EBCT results have led to further testing which has proven to be unnecessary. In other situations, there may be significant artery narrowing without calcium deposits and so the EBCT results may be falsely reassuring. Given these limitations, the exact usefulness of EBCT has yet to be determined. Given the limited information that is given by the test it is doubtful that it will continue to emerge as a needed diagnostic tool. The newer 64 slice CT scanners are able to show a large portion of the coronary arterial tree when the same angiographic contrast media (dye) use at coronary angiography is given. Unfortunately, although good images are attained, the radiation from this test is currently higher than that of cardiac catheterization with coronary angiography.
Laboratory blood tests have a use in the evaluation of patients with angina, but only in certain instances. Patients with possible unstable angina or heart attack are evaluated with blood tests in the emergency department or hospital. Heart enzymes (like creatine phosphokinase or CPK) and proteins (like myoglobin and troponins) can be measured in the blood in situations of prolonged or unstable symptoms, to determine whether heart damage has occurred. Blood tests are also useful in determining or monitoring a person's risk factors for CAD, like cholesterol, diabetes, or homocysteine. Unfortunately, unless someone is having a heart attack, no blood tests can tell definitely whether or not a person has CAD.
How is angina treated?
Those with risk factors for CAD such as diabetes, high blood pressure, and high blood cholesterol levels should control them with lifestyle modifications (exercise, controlling body weight, and an appropriate diet) and medications (there are many).
Even for those without these risk factors, everyone with angina or at risk for CAD should make lifestyle modifications to reduce and sometimes reverse the development of CAD. This includes quitting any smoking or drug use, eating a diet low in cholesterol and saturated fat, exercising regularly, and maintaining a lean body weight.
Many medications can help reduce the symptoms of angina. Medications used for stable angina include nitroglycerine (short- and long-acting), beta blockers, and calcium channel blockers, all of which help to balance the heart's supply and demand for blood. ACE-inhibitors reduce the risk of heart attack in those with CAD. Aspirin is very helpful in reducing the chance of clot formation and heart attack, and it and several other medications may help by reducing inflammation within the plaques.
A supervised exercise program, cardiac rehabilitation, can help increase exercise tolerance in those with CAD, especially after a heart attack or a heart procedure like angioplasty or bypass surgery.
Beyond medications, there are three procedures that directly improve blood flow to the heart:
- Coronary artery bypass grafting (abbreviated CAB or CABG)
- Enhanced external counter-pulsation (EECP)
Choosing which procedure is best depends on a particular patient's overall condition as well as the severity and distribution of coronary artery blockages. Angioplasty (also known by the abbreviation PTCA, for Percutaneous Transluminal Coronary Angioplasty) can be done immediately following an angiogram or at a later date. The procedure involves passing a small balloon catheter across the artery blockage and inflating it; most of the time the blockage will then stay open. In addition, a small wire-mesh scaffolding, called a stent, may be left behind within the blockage to minimize the chance of reclosure.
Coronary artery bypass surgery is a major surgical procedure involving stitching vein or artery sections from the aorta onto the coronary arteries, beyond the blockages. This restores blood-flow to previously deprived areas of the heart. The original technique is performed with the heart completely stopped and the blood flow to the brain and body maintained by a cardiopulmonary bypass machine. The newer off-pump coronary artery bypass method (OP-CAB) is possible for some patients. With OP-CAB, the cardiopulmonary bypass machine is not needed and the risk of stroke may therefore be reduced. As a result, the heart can recover faster because its beating was not stopped for the surgery. For those with limited blockages in certain locations on the heart, a minimally invasive procedure (MIDCAB) may be possible.
Angioplasty, angioplasty with stenting, or any method of bypass surgery may also be performed electively in those with stable angina who are determined to be in need of surgery. For those with unstable angina, any of these may need to be performed on an emergency basis
Enhanced external counter-pulsation (EECP) is a technique for improving blood flow to the heart without involving surgery. It involves 35 hour-long sessions once or twice a day in which cuffs (like large blood pressure cuffs) are inflated and deflated on both legs in synchronization with the heartbeat. Over the course of treatment, the pattern of blood flow to the heart may change, providing benefit and decreasing angina symptoms even for many months after the treatment has ended.
Where can I learn more about angina?
You can learn more about the causes, symptoms, and treatment of angina and coronary artery disease by using these as search terms on MyHeartCentral.com. The American Heart Association (americanheart.org), American College of Cardiology (acc.org) and National Heart, Lung, and Blood Institute (nhlbi.nih.gov) have information available on their websites as well.
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