Angina, in full angina pectoris, is chest pain or pressure, usually caused by insufficient blood flow to the heart muscle (myocardium). It is most commonly a symptom of coronary artery disease.
Angina is typically the result of partial obstruction or spasm of the arteries that supply blood to the heart muscle. The main mechanism of coronary artery obstruction is atherosclerosis as part of coronary artery disease. Other causes of angina include abnormal heart rhythms, heart failure and, less commonly, anemia. The term derives , and can therefore be translated as "a strangling feeling in the chest".
An urgent medical assessment is suggested to rule out serious medical conditions. There is a relationship between severity of angina and degree of oxygen deprivation in the heart muscle. However, the severity of angina does not always match the degree of oxygen deprivation to the heart or the risk of a heart attack (myocardial infarction). Some people may experience severe pain even though there is little risk of a heart attack whilst others may have a heart attack and experience little or no pain. In some cases, angina can be quite severe. Worsening angina attacks, sudden-onset angina at rest, and angina lasting more than 15 minutes are symptoms of unstable angina (usually grouped with similar conditions as the acute coronary syndrome). As these may precede a heart attack, they require urgent medical attention and are, in general, treated similarly to heart attacks.
In the early 20th century, severe angina was seen as a sign of impending death. However, modern medical therapies have improved the outlook substantially. Middle-age patients who experience moderate to severe angina (grading by classes II, III, and IV) have a five-year survival rate of approximately 92%.
Classification
Stable angina Also known as 'effort angina', this refers to the classic type of angina related to myocardial ischemia. A typical presentation of stable angina is that of chest discomfort and associated symptoms precipitated by some activity (running, walking, etc.) with minimal or non-existent symptoms at rest or after administration of sublingual nitroglycerin. Symptoms typically diminish several minutes after activity and recur when activity resumes. In this way, stable angina may be thought of as being similar to intermittent claudication symptoms. Other recognized precipitants of stable angina include cold weather, heavy meals, and emotional stress.
Unstable angina
Unstable angina (UA) (also "crescendo angina"; this is a form of acute coronary syndrome) is defined as angina pectoris that changes or worsens or begins suddenly at rest. Unstable angina is a medical emergency and requires urgent medical treatment from a doctor.
It has at least one of these three features: it occurs at rest (or with minimal exertion), usually lasting more than 10 minutes it is severe and of new-onset (i.e., within the prior 4–6 weeks) it occurs with a crescendo pattern (i.e., distinctly more severe, prolonged, or frequent than before).
UA may occur often unpredictably and even at rest, which may be a serious indicator of an impending heart attack. The primary factor differentiating unstable angina from stable angina (other than symptoms) is the underlying pathophysiology of the atherosclerosis. The pathophysiology of unstable angina is the reduction of coronary blood flow due to transient platelet aggregation on apparently normal endothelium, coronary artery spasms, or coronary thrombosis.
The process starts with atherosclerosis, progresses through inflammation to yield an active unstable plaque, which undergoes thrombosis and results in acute myocardial ischemia, which, if not reversed, results in cell necrosis (infarction). Studies show that 64% of all unstable anginas occur between 22:00 and 08:00 when patients are at rest.
In stable angina, the developing atheroma (a fatty plaque) is protected with a fibrous cap. This cap may rupture in unstable angina, allowing blood clots to precipitate and further decrease the area of the coronary vessel's lumen or the interior open space within an artery. This explains why, in many cases, unstable angina develops independently of activity.
Microvascular angina
Microvascular angina, also known as cardiac syndrome X, is characterized by angina-like chest pain, in the context of normal epicardial coronary arteries (the largest vessels on the surface of the heart, prior to significant branching) on angiography. The original definition of cardiac syndrome X also mandated that ischemic changes on exercise (despite normal coronary arteries) were displayed, as shown on cardiac stress tests. The primary cause of microvascular angina is unknown, but factors apparently involved are endothelial dysfunction and reduced flow (perhaps due to spasm) in the tiny "resistance" blood vessels of the heart.Guyton, Arthur. "Textbook of Medical Physiology" 11th edition. Philadelphia; Elsevier, 2006. Since microvascular angina is not characterized by major arterial blockages, it is harder to recognize and diagnose. .
Microvascular angina was previously considered a rather benign condition, but more recent data has changed this attitude. Studies, including the Women's Ischemia Syndrome Evaluation (WISE), suggest that microvascular angina is part of the pathophysiology of ischemic heart disease, perhaps explaining the higher rates of angina in females than in males, as well as their predilection towards ischemia and acute coronary syndromes in the absence of obstructive coronary artery disease.
Signs and symptoms
Angina pectoris can be quite painful, but many patients with angina complain of chest discomfort rather than actual pain: the discomfort is usually described as a pressure, heaviness, tightness, squeezing, burning, or choking sensation. Apart from chest discomfort, anginal pains may also be experienced in the epigastrium (upper central abdomen), back, neck area, jaw, or shoulders. This is explained by the concept of referred pain and is because the spinal level that receives visceral sensation from the heart simultaneously receives cutaneous sensation from parts of the skin specified by that spinal nerve's dermatome, without an ability to discriminate the two. Typical locations for referred pain are arms (often inner left arm), shoulders, and neck into the jaw. Angina is typically precipitated by exertion or emotional stress. It is exacerbated by having a full stomach and by cold temperatures. Pain may be accompanied by breathlessness, sweating, and nausea in some cases. In this case, the pulse rate and the blood pressure increases. Chest pain lasting only a few seconds is normally not angina (such as precordial catch syndrome).
Myocardial ischemia comes about when the myocardium (the heart muscle) receives insufficient blood and oxygen to function normally either because of increased oxygen demand by the myocardium or because of decreased supply to the myocardium. This inadequate perfusion of blood and the resulting reduced delivery of oxygen and nutrients are directly correlated to blocked or narrowed blood vessels.
Some experience "autonomic symptoms" (related to increased activity of the autonomic nervous system) such as nausea, vomiting, and pallor.
A variant form of angina—Prinzmetal's angina—occurs in patients with normal coronary arteries or insignificant atherosclerosis. It is believed caused by spasms of the artery. It occurs more in younger women.
Coital angina, also known as angina d'amour, is angina subsequent to sexual intercourse. It is generally rare, except in patients with severe coronary artery disease.
Cause Major risk factors
Routine counseling of adults by physicians to advise them to improve their diet and increase their physical activity has, in general, been found to induce only small changes in actual behavior. Therefore, as of 2012, the U.S. Preventive Services Task Force does not recommend routine lifestyle counseling of all patients without known cardiovascular disease, hypertension, hyperlipidemia, or diabetes, and instead recommends selectively counseling only those patients who seem most ready to make lifestyle changes and using available time with other patients to explore other types of intervention that would be more likely to have a preventative impact.
Conditions that exacerbate or provoke angina
One study found that smokers with coronary artery disease had a significantly increased level of sympathetic nerve activity when compared to those without. This is in addition to increases in blood pressure, heart rate, and peripheral vascular resistance associated with nicotine, which may lead to recurrent angina attacks. In addition, the Centers for Disease Control and Prevention (CDC) reports that the risk of CHD (Coronary heart disease), stroke, and PVD (Peripheral vascular disease) is reduced within 1–2 years of smoking cessation. In another study, it was found that, after one year, the prevalence of angina in smoking males under 60 after an initial attack was 40% less in those having quit smoking compared to those that continued. Studies have found that there are short-term and long-term benefits to smoking cessation.
Other medical problems Esophageal disorders Gastroesophageal reflux disease (GERD) Hyperthyroidism Hypoxemia Profound anemia Uncontrolled hypertension
Other cardiac problems Bradyarrhythmia Hypertrophic cardiomyopathy Tachyarrhythmia Valvular heart disease
Myocardial ischemia can result from: a reduction of blood flow to the heart that can be caused by stenosis, spasm, or acute occlusion (by an embolus) of the heart's arteries. resistance of the blood vessels. This can be caused by narrowing of the blood vessels; a decrease in radius. Blood flow is proportional to the radius of the artery to the fourth power. reduced oxygen-carrying capacity of the blood, due to several factors such as a decrease in oxygen tension and hemoglobin concentration. This decreases the ability of hemoglobin to carry oxygen to myocardial tissue.
Atherosclerosis is the most common cause of stenosis (narrowing of the blood vessels) of the heart's arteries and, hence, angina pectoris. Some people with chest pain have normal or minimal narrowing of heart arteries; in these patients, vasospasm is a more likely cause for the pain, sometimes in the context of Prinzmetal's angina and syndrome X.
Myocardial ischemia also can be the result of factors affecting blood composition, such as the reduced oxygen-carrying capacity of blood, as seen with severe anemia (low number of red blood cells), or long-term smoking.
Pathophysiology Angina results when there is an imbalance between the heart's oxygen demand and supply. This imbalance can result from an increase in demand (e.g., during exercise) without a proportional increase in supply (e.g., due to obstruction or atherosclerosis of the coronary arteries).
However, the pathophysiology of angina in females varies significantly as compared to males. Non-obstructive coronary disease is more common in females.
Diagnosis Angina should be suspected in people presenting tight, dull, or heavy chest discomfort that is:NHS Clinical Knowledge Summaries (2009) Angina – stable. Date site accessed: 04/01/2009. Retrosternal or left-sided, radiating to the left arm, neck, jaw, or back. Associated with exertion or emotional stress and relieved within several minutes by rest. Precipitated by cold weather or a meal.
Some people present with atypical symptoms, including breathlessness, nausea, or epigastric discomfort, or burning. These atypical symptoms are particularly likely in older people, women, and those with diabetes.