Angina Pectoris Pathophysiology ,therapy ,assyssment and planing

Angina Pectoris

Angina pectoris is a clinical syndrome usually characterized by episodes or paroxysms of pain or pressure in the anterior chest. The cause is insufficient coronary blood flow, resulting in a decreased oxygen supply when there is increased myocardial demand for oxygen in response to physical exertion or emotional stress. In other words, the need for oxygen exceeds the supply. The severity of angina is based on the precipitating activity and its effect on activities of daily living.

Pathophysiology

Angina is usually caused by atherosclerotic disease. Almost invariably, angina is associated with a significant obstruction of a major coronary artery. Normally, the myocardium extracts a large amount of oxygen from the coronary circulation to meet its continuous demands. When there is an increase in demand, flow through the coronary arteries needs to be increased. When there is blockage in a coronary artery, flow cannot be increased, and ischemia results.

Several factors are associated with typical anginal pain:

• Physical exertion, which can precipitate an attack by increasing myocardial oxygen demand
• Exposure to cold, which can cause vasoconstriction and elevated blood pressure, with increased oxygen demand
• Eating a heavy meal, which increases the blood flow to the mesenteric area for digestion, thereby reducing the blood supply available to the heart muscle. In a severely compromised heart, shunting of blood for digestion can be sufficient to induce anginal pain.
• Stress or any emotion-provoking situation, causing the release of catecholamines, which increases blood pressure, heart rate, and myocardial workload

Types of Angina

• Stable angina: predictable and consistent pain that occurs on exertion and is relieved by rest
• Unstable angina (also called preinfarction angina or crescendo angina): symptoms occur more frequently and last longer than stable angina. The threshold for pain is lower, and pain may occur at rest.
• Intractable or refractory angina: severe incapacitating chest pain
• Variant angina (also called Prinzmetal's angina): pain at rest with reversible ST-segment elevation; thought to be caused by coronary artery vasospasm
• Silent ischemia: objective evidence of ischemia (such as ECG changes with a stress test), but patient reports no symptoms

Atypical angina is not associated with these listed factors. It may occur at rest.

Clinical Manifestations

Ischemia of the heart muscle may produce pain or other symptoms, varying in severity from mild indigestion to a choking or heavy sensation in the upper chest that ranges from discomfort to agonizing pain accompanied by severe apprehension and a feeling of impending death. The pain is often felt deep in the chest behind the sternum (retrosternal area). Typically, the pain or discomfort is poorly localized and may radiate to the neck, jaw, shoulders, and inner aspects of the upper arms, usually the left arm. The patient often feels tightness or a heavy, choking, or strangling sensation that has a viselike, insistent quality. The patient with diabetes mellitus may not have severe pain with angina because diabetic neuropathy can blunt nociceptors' transmission, dulling the perception of pain. A woman may have different symptoms than a man, because coronary disease in women tends to be more diffuse and affects long segments of the artery rather than discrete segments.

A feeling of weakness or numbness in the arms, wrists, and hands, as well as shortness of breath, pallor, diaphoresis, dizziness or lightheadedness, and nausea and vomiting, may accompany the pain. Anxiety may occur with angina. An important characteristic of angina is that it subsides with

rest or nitroglycerin. In many patients, anginal symptoms follow a stable, predictable pattern.

Pharmacologic Therapy

1- Nitroglycerin

Nitrates remain the mainstay for treatment of angina pectoris. A vasoactive agent, nitroglycerin (Nitrostat, Nitrol, Nitro-Bid) is administered to reduce myocardial oxygen consumption, which decreases ischemia and relieves pain. Nitroglycerin dilates primarily the veins and, in higher doses, also the arteries. Dilation of the veins causes venous pooling of blood throughout the body. As a result, less blood returns to the heart, and filling pressure (preload) is reduced. If the patient is hypovolemic (does not have adequate circulating blood volume), the decrease in filling pressure can cause a significant decrease in cardiac output and blood pressure.

Nitrates in higher doses also relax the systemic arteriolar bed, lowering blood pressure and decreasing afterload. These effects decrease myocardial oxygen requirements and increase oxygen supply, bringing about a more favorable balance between supply and demand.

Nitroglycerin may be given by several routes: sublingual tablet or spray, oral capsule, topical agent, and intravenous (IV) administration. Sublingual nitroglycerin is generally placed under the tongue or in the cheek (buccal pouch) and alleviates the pain of ischemia within 3 minutes. The patches are often applied in the morning and removed at bedtime. This regimen allows for a nitrate-free period to prevent the development of tolerance.

A continuous or intermittent IV infusion of nitroglycerin may be administered to the hospitalized patient with recurring signs and symptoms of ischemia or after a revascularization procedure. The amount of nitroglycerin administered is based on the patient's symptoms while avoiding side effects such as hypotension. It usually is not administered if the systolic blood pressure is 90 mm Hg or less. Generally, after the patient is symptom-free, the nitroglycerin may be switched to a topical preparation within 24 hours.

2- Beta-Adrenergic Blocking Agents

Beta-blockers such as metoprolol (Lopressor, Toprol) and atenolol (Tenormin) reduce myocardial oxygen consumption by blocking beta-adrenergic sympathetic stimulation to the heart. The result is a reduction in heart rate, slowed conduction of impulses through the conduction system, decreased blood pressure, and reduced myocardial contractility (force of contraction) to balance the myocardial oxygen needs (demands) and the amount of oxygen available (supply). This helps control chest pain and delays the onset of ischemia during work or exercise. Beta-blockers reduce the incidence of recurrent angina, infarction, and cardiac mortality. The dose can be titrated to achieve a resting heart rate of 50 to 60 beats per minute.

Cardiac side effects and possible contraindications include hypotension, bradycardia, advanced atrioventricular block, and decompensated heart failure. If a beta-blocker is given IV for an acute cardiac event, the ECG, blood pressure, and heart rate are monitored closely after the medication has been administered. Because some beta-blockers also affect the beta-adrenergic receptors in the bronchioles, causing bronchoconstriction, they are contraindicated in patients with significant pulmonary obstructive diseases, such as asthma. Other side effects include depression, fatigue, decreased libido, and masking of symptoms of hypoglycemia. Patients taking beta-blockers are cautioned not to stop taking them abruptly, because angina may worsen and MI may develop. Beta-blocker therapy should be decreased gradually over several days before being discontinued.

 Patients with diabetes who take beta-blockers are instructed to monitor their blood glucose levels often and to observe for signs and symptoms of hypoglycemia.

3-Calcium Channel Blocking Agents

Calcium channel blockers (calcium ion antagonists) have a variety of effects. These agents decrease sinoatrial node automaticity and atrioventricular node conduction, resulting in a slower heart rate and a decrease in the strength of the heart muscle contraction (negative inotropic effect). These effects decrease the workload of the heart. Calcium channel blockers also relax the blood vessels, causing a decrease in blood pressure and an increase in coronary artery perfusion. Calcium channel blockers increase myocardial oxygen supply by dilating the smooth muscle wall of the coronary arterioles; they decrease myocardial oxygen demand by reducing systemic arterial pressure and the workload of the left ventricle.

The calcium channel blockers most commonly used are amlodipine (Norvasc) and diltiazem (Cardizem, Tiazac). They may be used by patients who cannot take beta-blockers, who develop significant side effects from beta-blockers or nitrates, or who still have pain despite beta-blocker and nitroglycerin therapy. Calcium channel blockers are also used to prevent and treat vasospasm, which commonly occurs after an invasive interventional procedure.

First-generation calcium channel blockers such as nifedipine should be avoided or used with great caution in people with heart failure, because they decrease myocardial contractility. Amlodipine and felodipine (Plendil) are the calcium channel blockers of choice for patients with heart failure. Hypotension may occur after the IV administration of any of the calcium channel blockers. Other side effects may include atrioventricular block, bradycardia, constipation, and gastric distress.

4-Antiplatelet and Anticoagulant Medications

Antiplatelet medications are administered to prevent platelet aggregation and subsequent thrombosis, which impedes blood flow.

5-Aspirin

Aspirin prevents platelet activation and reduces the incidence of MI and death in patients with CAD. A 160- to 325-mg dose of aspirin should be given to the patient with angina as soon as the diagnosis is made (eg, in the emergency department or physician's office) and then continued with 81 to 325 mg daily. Although aspirin may be one of the most important medications in the treatment of CAD, it may be overlooked because of its low cost and common use. Patients should be advised to continue aspirin even if they concurrently take nonsteroidal anti-inflammatory drugs (NSAIDs) or other analgesics. Because aspirin may cause gastrointestinal upset and bleeding, the use of H₂-blockers (eg, famotidine [Pepcid], ranitidine [Zantac]) or proton pump inhibitors (eg, omeprazole [Prilosec]) should be considered to allow continued aspirin therapy.

6-Oxygen Administration

Oxygen therapy is usually initiated at the onset of chest pain in an attempt to increase the amount of oxygen delivered to the myocardium and to decrease pain. The therapeutic effectiveness of oxygen is determined by observing the rate and rhythm of respirations. Blood oxygen saturation is monitored by pulse oximetry; the normal oxygen saturation (SpO₂) level is greater than 93%.

Nursing Process

The Patient With Angina Pectoris

Assessment

The nurse gathers information about the patient's symptoms and activities, especially those that precede and precipitate attacks of angina pectoris. using a PQRST format.

 Other helpful questions may be asked: How long does the angina usually last? Does nitroglycerin relieve the angina? If so, how many tablets or sprays are needed to achieve relief? How long does it takes for relief to occur?

The answers to these questions form a basis for designing an effective program of treatment and prevention. In addition to assessing angina pectoris or its equivalent, the nurse also assesses the patient's risk factors for CAD, the patient's response to angina, the patient's and family's understanding of the diagnosis, and adherence to the current treatment plan.

Diagnosis

Nursing Diagnoses

Based on the assessment data, major nursing diagnoses may include:

• Ineffective cardiac tissue perfusion secondary to CAD, as evidenced by chest pain or equivalent symptoms
• Death anxiety
• Deficient knowledge about the underlying disease and methods for avoiding complications
• Noncompliance, ineffective management of therapeutic regimen related to failure to accept necessary lifestyle changes

Collaborative Problems/Potential Complications

Potential complications that may develop include the following, which are discussed in the chapters indicated:

• Acute pulmonary edema
• Heart failure
• Cardiogenic shock
• Dysrhythmias and cardiac arrest
• MI

Planning and Goals

Major patient goals include immediate and appropriate treatment when angina occurs, prevention of angina, reduction of anxiety, awareness of the disease process and understanding of the prescribed care, adherence to the self-care program, and absence of complications.

Nursing Interventions

Treating Angina

If the patient reports pain (or the person's equivalent to pain), the nurse takes immediate action. When a patient experiences angina, the nurse directs the patient to stop all activities and sit or rest in bed in a semi-Fowler's position to reduce the oxygen requirements of the ischemic myocardium. The nurse assesses the patient's angina, asking questions to determine whether the angina is the same as the patient typically experiences. A change may indicate a worsening of the disease or a different cause. The nurse then continues to assess the patient, measuring vital signs and observing for signs of respiratory distress. If the patient is in the hospital, a 12-lead ECG is usually obtained and scrutinized for ST-segment and T-wave changes. If the patient has been placed on cardiac monitoring with continuous ST-segment monitoring, the ST segment is assessed for changes.

Nitroglycerin is administered sublingually, and the patient's response is assessed (relief of chest pain and effect on blood pressure and heart rate). If the chest pain is unchanged or is lessened but still present, nitroglycerin administration is repeated up to three doses. Each time blood pressure, heart rate, and the ST segment (if the patient is on a monitor with ST-segment monitoring capability) are assessed. The nurse administers oxygen therapy if the patient's respiratory rate is increased or if the oxygen saturation level is decreased. Oxygen is usually administered at 2 L/min by nasal cannula, even without evidence of respiratory distress, although there is no documentation of its effect on outcome. If the pain is significant and continues after these interventions, the patient is further evaluated for acute MI and may be transferred to a higher-acuity nursing unit.

Reducing Anxiety

Patients with angina often fear loss of their roles within society and the family. They may also fear that the pain may lead to an MI or death. Exploring the implications that the diagnosis has for the patient and providing information about the illness, its treatment, and methods of preventing its progression are important nursing interventions. Various stress reduction methods should be explored with the patient. For example, music therapy, in which patients listen to selected music through headphones, has been shown to reduce anxiety in patients who are in a coronary care unit and may serve as an adjunct to therapeutic communication. Addressing the spiritual needs of the patient and family may also assist in allaying anxieties and fears.

Preventing Pain

The nurse reviews the assessment findings, identifies the level of activity that causes the patient's pain, and plans the patient's activities accordingly. If the patient has pain frequently or with minimal activity, the nurse alternates the patient's activities with rest periods. Balancing activity and rest is an important aspect of the educational plan for the patient and family.

Promoting Home and Community-Based Care

Teaching Patients Self-Care

Learning about the modifiable risk factors that contribute to the development of CAD and resulting angina is essential. Exploring what the patient and family see as their priorities in managing the disease and developing a plan based on those priorities can assist with patient adherence to the therapeutic regimen. It is important to explore with the patient methods to avoid, modify, or adapt the triggers for anginal pain. The teaching program for the patient with angina is designed so that the patient and family understand the illness, identify the symptoms of myocardial ischemia, state the actions to take when symptoms develop, and discuss methods to prevent chest pain and the advancement of CAD. The goals of the educational program are to reduce the frequency and severity of anginal attacks, to delay the progress of the underlying disease if possible, and to prevent complications.

The self-care program is prepared in collaboration with the patient and family or friends. Activities should be planned to minimize the occurrence of angina episodes. The patient needs to understand that any pain unrelieved within 15 minutes by the usual methods, including nitroglycerin  should be treated at the closest emergency center

Evaluation

Expected Patient Outcomes

Expected patient outcomes may include:

• Reports that pain is relieved promptly
• Recognizes symptoms
• Takes immediate action
• Seeks medical assistance if pain persists or changes in quality
• Reports decreased anxiety
• Expresses acceptance of diagnosis
• Expresses control over choices within medical regimen
• Does not exhibit signs and symptoms that indicate a high level of anxiety
• Understands ways to avoid complications and is free of complications
• Describes the process of angina
• Explains reasons for measures to prevent complications
• Exhibits normal ECG and cardiac biomarkers
• Experiences no signs and symptoms of acute MI
• Adheres to self-care program
• Takes medications as prescribed
• Keeps health care appointments
• Implements plan to reduce risk factors