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Angina Pectoris


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Angina Pectoris

2. 1. Definition, Etiology, and Pathophysiology

Angina pectoris is a clinical syndrome characterized by paroxysm of pain or a feeling of pressure in the anterior chest. The cause is considered to be insufficient coronary blood flow, resulting in inadequate oxygen supply of the myocardium; in other words, myocardial oxygen demands exceed supply.

Angina is usually caused by atherosclerotic heart disease, and almost invariably is associated with a significant obstruction of a major coronary artery. (The characteristics of the various types angina are listed in next table.

Types of Angina

Unstable Angina (Preinfarction Angina; Crescendo Angina)

Angina Decubitis

Progressive increase in frequency, intensity, and duration of anginal attacks

Angina while lying down

Intractable of Refractory Angina

Chronic Stable Angina

Severe incapacitating angina

Predictable consistent, occurs on exertion and is relieved and duration by rest

Prinzmetal s Angina (Variant:Resting)

Spontaneous type of anginal pain accompanied by ST-segment elevation in ECG

Thought to be due to coronary artery spasm

Associated with high risk of infarction

Nocturnal Angina

Pain occurs at night usually during sleep; may be relieved by sitting upright

Commonly due to left ventricular failure

Silent Ischemia

Objective evidence of ischemia (such as stress test), but patient is asymptomatic

A number of factors can produce anginal pain:

physical exertion can precipitate an attack by increasing myocardial oxygen demands;

exposure to cold can cause vasoconstriction and an elevated blood pressure, with increased oxygen demand;

eating a heavy meal increases the blood flow to the mesenteric area for digestion, thus reducing the available blood supply to the heart.

In a severely compromised heart, the shunting of blood for digestion can be sufficient to induce anginal pain. Stress or any emotion provoking situation causing the release of adrenalin and increased blood pressure may accelerate the heart rate, thus increasing myocardial workload.

2.2. Clinical Manifestations

Ischemia of the heart muscle produces pain, varying in severity from upper substernal pressure to agonizing pain that is accompanied by severe apprehension and a feeling of impending death. The pain is usually felt deep in the chest behind the upper or middle third of the sternum (retrosternal).Although the pain frequently is localized, it may radiate to the neck, jaw, shoulders, and inner aspects of the upper extremities. The patient often experiences a tightness, a choking or strangling sensation that has a viselike, insistent quality. A feeling of weakness of numbness in the arms, wrists, and hands may accompany the pain.Along with the physical pain, the patient may also have a sense of impending death, an apprehension so characteristic of angina that if it occurs alone, as it sometimes does, it is sufficient for diagnosis. An important characteristic of anginal pain is that it subsides when the precipitating cause is removed.

2.3. Gerontologic Consideration

The elderly person who experiences angina may not exhibit the typical pain profile because of changes in neuroreceptors. Pain is often manifested in the elderly as

weakness or fainting. When exposed to cold temperatures, elderly persons mey experience anginal symptoms more quickly than younger persons because they have less subcutaneous fat to provide insulation. They should be encouraged to dress with extra clothing and advised to recognize feeling of weakness as an indication that they should rest or take prescribed medication.

2.4. Diagnostic Evaluation

The diagnosis of angina is often made by an evaluation of the clinical manifestation of pain and patient s manifestations of pain and the patient s history. In certain types of angina, electrocardiogram (ECG) changes are helpful in making a differential diagnosis of the angina. The patients response to exertion or stress also may be tested by means of electrocardiographic monitoring while the patient exercises on a bicycle or treadmill.

2.5. Tests

The goal of testing for angina is to distinguish between chest pain that is not heart-related (such as that due to skeletal muscle injury), that is due to treatable angina (not heart damage), and that is due to a heart attack. When a patient presents to the emergency room with an acute coronary syndrome – a group of symptoms that suggest heart injury – they are evaluated with a variety of laboratory and non-laboratory tests. These are used to determine the cause of the pain and the severity of the condition. Since some treatments for a heart attack must be given within a short period of time to minimize heart damage, an accurate diagnosis must be quickly confirmed.

2.5.1. Test Laboratory

Cardiac biomarkers, proteins that are released when muscle cells are damaged, are frequently ordered to help differentiate angina from a heart attack. These include:

1. Troponin - the most commonly ordered and cardiac-specific of the markers; will be elevated within a few hours of heart damage and remain elevated for up to two weeks

2. CK-MB – one particular form of the enzyme creatine kinase that is found mostly in heart muscle and rises when there is damage to the heart muscle cells

3. BNP or NT-proBNP – released by the body as a natural response to heart failure; increased levels of BNP, while not diagnostic for a heart attack, indicate an increased risk of cardiac problems in persons with acute coronary syndrome

4. Myoglobin – a protein released into the blood when heart or other skeletal muscle is injured

One or more of these tests are usually ordered initially and then 1 or 2 more times in the next 12 to 16 hours to look at changes in concentrations. If these cardiac biomarkers are normal, then it is much less likely that the symptoms and chest pain are due to heart muscle damage and more likely that the pain is due to angina.

` Other more general screening tests may also be ordered to help evaluate the patient’s major body organs, electrolyte balance, blood sugar, and red and white blood cells to see whether there are any excesses, deficiencies, or dysfunctions that may be causing or exacerbating the patient’s symptoms. These include:

Comprehensive Metabolic Panel– a group of usually 14 tests that is used as a broad screening tool to asses the current status of a person’s kidneys, liver, electrolyte and acid/base balance, blood sugar, and blood proteins

Complete Blood Count – a test used to determine a person’s general health status and to screen for a variety of disorders, such as anemia and infection

2.5.2. Evaluations  Non - Laborator

A range of non-laboratory evaluations and tests are used to assess chest pain and other symptoms. These include:

1. A medical history, including an evaluation of risk factors such as age, CAD, diabetes, and smoking

2. A physical examination

3. An electrocardiography (ECG or EKG) – a test that looks at the heart’s electrical activity andrhythm

Continuous ECG monitoring – the patient wears a monitor that evaluates heart rhythm over a period of time

Based on the findings of these tests, other procedures may be necessary, including:

1. An exercise stress test

2. Chest X-ray

3. Radionuclide imaging – a radioactive compound is injected into the blood to evaluate blood flow and show images of narrowed blood vessels around the heart

4. Echocardiography – ultrasound imaging of the heart

5. Coronary catheterization – in this procedure, a thin flexible tube is inserted into an artery in the leg and threaded up to the coronary arteries to evaluate blood flow and pressure in the heart and the status of the arteries in the heart

6. Coronary angiography – X-rays of arteries using a radiopaque dye to help diagnose CAD; this procedure is performed during coronary catheterization

2.6. Medical management

The objectives of medical management of angina are to decrease the oxygen demands of myocardium and to increase the oxygen supply. Medically these objectives are met through pharmacologic therapy and risk factor control. Surgically the objectives are met by revascularization of the blood supply to the myocardium, through coronary

artery bypass surgery or percutaneous transluminal coronary angioplasty (PTCA), an interventional radiologic variant of surgery. Frequently a combination of medical and surgical therapies is employed.

Currently there are several new approaches being investigated to revascularize the myocardium. The application of intracoronary stents to enhance blood flow, the use of laser lights to vaporize plaques, and the use of percutaneous coronary endarterectomy to extract obstructions are three major achievements that hold great promise for the patient with coronary artery disease.

Pharmacologic therapy

1.Nitroglycerin- the nitrates remain the mainstay of treatment for angina pectoris. Nitroglycerin is administered to reduce myocardial oxygen consumption, which decreases ischemia and relieves anginal pain. Nitroglycerin is a vasoactive drug that acts to dilate both the veins and the arteries and thus has an effect on the peripheral circulation. Dilation of the veins cause venous pooling of the blood throughout the body. As a result, less blood is returned to the heart and there is a reduction in filling pressure. Nitrates also relax systemic arteriolar bed and thus cause a fall in blood pressure. The effects decrease myocardial oxygen requirements, bringing about a more favorable balance between supply and demand.

Nitroglycerin taken sublingually or in the buccal pouch alleviates the pain of ischemia within 3 minutes.

Side effects of nitroglycerin include flushing, throbbing headache, hypotension and tachycardia. The use of long – acting nitrate preparations is controversial. Isosorbide dinitratew appears to be effective for up to 2 hours if taken sublingually, but hes an uncertain effect if taken orally.

Beta – Adrenergic Blockers – It the patient continues to have chest pain despite treatment with nitrogycerin and modification of life style, a beta-adrenergic blocking agent is recommended. Propranolol hydrochloride remains the drugs of choice. The drug appears to reduce myocardial oxygen consumption by blocking the sympathetic

impulses to the heart. The result is a reduction in heart rate, blood pressure, and myocardial contractility that establishes a more favorable balance between myocardial oxygen needs and the amount of oxygen available. Propanolol  may be given with sublingual isosorbide dinitrate for anti – anginal and anti – ischemia prophylaxis.

Propanolol is cleared by the liver at varying rates, depending on the individual patient. It is usually given a 6-hour intervals. Side effects include musculoskeletal weakness, hypotension, bradycardia and mental depression.

3. Calcium Ion Antagonists/Channel Blockers – The calcium channel blockers or antagonists, possess properties that have profound effects on myocardial oxygen demands and supply, hence their value in the treatment of angina. Physiologically the calcium ion performs at the cellular level to influence contraction of all types of muscle tissue and plays a role in the electrical stimulation of the heart.

Calcium ion antagonists/blockers increase myocardial oxygen supply by dilating the smooth muscle wall of the coronary arterioles, and decrease myocardial oxygen demands by reducing systemic arterial pressure and thus the workload of the left ventricle.

The three calcium ion antagonists/blockers most commonly used are nifedipine, verapamil and diltiazem. The vasodilating effects of these agents, particularly on the coronary circulation, have made them valuable in angina that results from coronary vasospasm. Calcium blockers should be used with great caution in individuals with heart failure because they block the calcium that supports contractility. Hypotension may occur after intravenous administration. Other side effects that may occur constipation, gastric, distress, dizziness or headache associated with dizziness.

Calcium ion antagonists/blockers usually administered every 4 to 6 hours.

2.7. Risk Factor Control

Several other measures may be necessary to decrease the oxygen demands of the myocardium. It is important that the patient stop smoking, because smoking produces

tachycardia and raises the blood pressure, thus increasing the work of the heart. Obese persons are advised to lose weight to reduce cardiac work.

2.8. Percutaneous Transluminal Coronary Angioplasty

Angina pectoris may persist for many years in a stable form with brief attacks. It is a serious disease, however. In the unstable stage, the episodes of chest pain become more frequent and intense, occurring without apparent provocation. When symptoms cannot be controlled despite an adequate trial of drug therapy, some form of revascularization is considered that can correct the basic problem by bringing a new blood supply to the ischemic myocardium.

Interventional radiology has made possible a procedure for the revascularization of the coronary arteries that is less invasive than bypass surgery. The procedure is referred to aspercutaneous transluminal coronary angioplasty. A balloon-tipped catheter is inserted into the coronary artery and rapidly inflated and deflated. The purpose of this procedure is to compress the atheroma into the intimal lining of the artery, thereby increasing blood flow in the artery.

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