Angina

ntroduction to angina

Chest pain is a common symptom that is caused by many different conditions. Some causes require prompt medical attention, such as angina, heart attack, or tearing of the aorta. Other causes of chest pain that may not require immediate medical intervention include spasm of the esophagus, gallbladder attack, or inflammation of the chest wall. An accurate diagnosis is important in providing proper treatment to patients with chest pain.
The diagnosis and treatment of angina is discussed below, as well as the diagnosis of other causes of chest pain that can mimic angina.

What is angina, and what are the symptoms of angina?

Angina (angina pectoris - Latin for squeezing of the chest) is chest discomfort that occurs when there is a decreased blood oxygen supply to an area of the heart muscle. In most cases, the lack of blood supply is due to a narrowing of the coronary arteries as a result of arteriosclerosis.
Angina is usually felt as:

• pressure,
  
• heaviness,
  
• tightening,
  
• squeezing, or
  
• aching across the chest, particularly behind the breastbone.

This pain often radiates to the neck, jaw, arms, back, or even the teeth.
Patients may also suffer:

• indigestion,
  
• heartburn,
  
• weakness,
  
• sweating,
  
• nausea,
  
• cramping, and
  
• shortness of breath.

Angina usually occurs during exertion, severe emotional stress, or after a heavy meal. During these periods, the heart muscle demands more blood oxygen than the narrowed coronary arteries can deliver. Angina typically lasts from 1 to 15 minutes and is relieved by rest or by placing a nitroglycerin tablet under the tongue. Nitroglycerin relaxes the blood vessels and lowers blood pressure. Both rest and nitroglycerin decrease the heart muscles demand for oxygen, thus relieving angina.
Angina is classified in one of two types: 1) stable angina or 2) unstable angina.
Stable angina
Stable angina is the most common type of angina, and what most people mean when they refer to angina. People with stable angina have angina symptoms on a regular basis and the symptoms are somewhat predictable (for example, walking up a flight of steps causes chest pain). For most patients, symptoms occur during exertion and commonly last less than five minutes. They are relieved by rest or medication, such as nitroglycerin under the tongue.
Unstable angina
Unstable angina is less common and more serious. The symptoms are more severe and less predictable than the pattern of stable angina. Moreover, the pains are more frequent, last longer, occur at rest, and are not relieved by nitroglycerin under the tongue (or the patient needs to use more nitroglycerin than usual). Unstable angina is not the same as a heart attack, but it warrants an immediate visit to your healthcare provider or hospital emergency department as further cardiac testing is urgently needed. Unstable angina is often a precursor to a heart attack.

What causes angina?

The most common cause of angina is coronary artery disease. A less common cause of angina is spasm of the coronary arteries.
Coronary artery disease
Coronary arteries supply oxygenated blood to the heart muscle. Coronary artery disease develops as cholesterol is deposited in the artery wall, causing the formation of a hard, thick substance called cholesterol plaque. The accumulation of cholesterol plaque over time causes narrowing of the coronary arteries, a process called arteriosclerosis. Arteriosclerosis can be accelerated by smoking, high blood pressure, elevated cholesterol, and diabetes. When coronary arteries become narrowed by more than 50% to 70%, they can no longer meet the increased blood oxygen demand by the heart muscle during exercise or stress. Lack of oxygen to the heart muscle causes chest pain (angina).
Coronary artery spasm
The walls of the arteries are surrounded by muscle fibers. Rapid contraction of these muscle fibers causes a sudden narrowing (spasm) of the arteries. A spasm of the coronary arteries reduces blood to the heart muscle and causes angina. Angina as a result of a coronary artery spasm is called "variant" angina or Prinzmetal angina. Prinzmetal angina typically occurs at rest, usually in the early morning hours. Spasms can occur in normal coronary arteries as well as in those narrowed by arteriosclerosis.
Coronary artery spasm can also be caused by use/abuse of cocaine. The spasm of the artery wall caused by cocaine can be so significant that it can actually cause a heart attack.

What are other causes of chest pain?

In caring for patients with chest pain, the doctor distinguishes whether the pain is related to a lack of oxygen to the heart muscle (as in angina or heart attack), or is due to another process. Many conditions are considered that can cause chest pain which is similar to that of a heart attack or angina. Examples include the following:

• Pleuritis (pleurisy): Inflammation of the lining of the lungs (pleuritis) causes sharp chest pain, which is aggravated by deep breathing and coughing. Patients often notice shortness of breath, in part due to their shallow breathing to minimize chest pain. Viral infections are the most common causes of pleurisy. Other systemic inflammatory conditions, such as systemic lupus, can also cause pleurisy.
  
• Pericarditis: Pericarditis is inflammation of the lining around the heart. Symptoms of pericarditis are similar to that of pleuritis.
  
• Pneumonia: Pneumonia (bacterial infection of the lung) causes fever and chest pain. Chest pain in bacterial pneumonia is due to an irritation or infection of the lining of the lung (pleura).
  
• Pulmonary embolism: blood clots travel from the veins of the pelvis or the lower extremities to the lung, the condition is called pulmonary embolism. Pulmonary embolism can cause death of lung tissue (pulmonary infarction). Pulmonary infarction can lead to irritation of the pleura, causing chest pain similar to pleurisy. Some common causes of blood clots in these veins is deep vein thrombosis (prolonged immobility, recent surgery, trauma to the legs, or pelvic infection).
  
• Pneumothorax: Small sacs in the lung tissue (alveoli) can spontaneously burst, causing pneumothorax. Symptoms of pneumothorax include sudden, severe, sharp chest pain and shortness of breath. One common cause of pneumothorax is severe emphysema.
  
• Mitral valve prolapse: Mitral valve prolapse is a common heart valve abnormality, affecting 5% to 10% of the population. MVP is especially common among women between 20 to 40 years of age. Chest pain with MVP is usually sharp but not severe. Unlike angina, chest pain with MVP rarely occurs during or after exercise, and usually will not respond to nitroglycerin.
  
• Aortic dissection: The aorta is the major vessel delivering blood from the left ventricle to the rest of the body. Aortic dissection (tearing of the aorta wall) is a life-threatening emergency. Aortic dissection causes severe, unrelenting chest and back pain. Young adults with aortic dissection usually have Marfan's syndrome, an inherited disease in which an abnormal form of the structural protein called collagen causes weakness of the aortic wall. Older patients develop aortic dissection typically as a result of chronic, high blood pressure, in addition to generalized hardening of the arteries (arteriosclerosis).
  
• Costochondritis, rib fractures, muscle strain or spasm: Pain originating from the chest wall may be due to muscle strain or spasm, costochondritis, or rib fractures. Chest wall pain is usually sharp and constant. It is usually worsened by movement, coughing, deep breathing, and direct pressure on the area. Muscle spasm and strain can result from vigorous, unusual twisting and bending. The joints between the ribs and cartilage next to the breastbone can become inflamed, a condition called costochondritis. Fractured ribs resulting from trauma or cancer involvement can cause significant chest pain.
  
• Nerve compression: Compression of the nerve roots by bone spurs as they exit the spinal cord can cause pain. Nerve compression can also cause weakness and numbness in the upper arm and chest.
  
• Shingles (herpes zoster infection of the nerves): Shingles is nerve irritation from the infection, which can cause chest pain days before any typical rash appears.
  
• Esophageal spasm and reflux: The esophagus is the long muscular tube connecting the mouth to the stomach. Reflux, or regurgitation of stomach contents and acid into the esophagus can cause heartburn and chest pain. Spasm of the muscle of the esophagus can also cause chest pain which can be indistinguishable from chest pain caused by angina or a heart attack. The cause of esophageal muscle spasm is not known. Pain of esophageal spasm can respond to nitroglycerin in a similar manner as angina.
  
• Gallbladder attack (gallstones): Gallstones can block the gallbladder or bile ducts and cause severe pain of the upper abdomen, back and chest. Gallbladder attacks can mimic the pain of angina and heart attack.
  
• Anxiety and panic attacks: Anxiety, depression, and panic attacks are frequently associated with chest pain lasting from minutes to days. The pain can be sharp or dull. It is usually accompanied by shortness of breath, or the inability to take a deep breath. Emotional stress can aggravate chest pain, but the pain is generally not related to exertion, and is not relieved by nitroglycerin. These patients often breath too fast (hyperventilate), causing lightheadedness, numbness, and tingling in the lips and fingers. Coronary artery disease risk factors are typically absent in these patients. Since there is no test for panic attacks, patients with chest pain usually undergo tests to exclude coronary artery disease and other causes of chest pain.