Myocardial infarction (MI) results when myocardial tissue becomes necrotic because of absent or diminished blood supply. In the United States, approximately 1.5 million MIs occur each year and approximately 500,000 to 700,000 people die each year from ischemic heart disease. MI is one of the most common causes of death, with a mortality rate of approximately 25%. In addition, more than 50% of sudden deaths occur within 1 hour of the onset of symptoms. When myocardial tissue is deprived of oxygenated blood supply for a period of time, an area of myocardial necrosis develops; this necrosis is surrounded by injured and ischemic tissue. Pain usually develops from irritation of nerve endings in the ischemic and injured areas. The typical chest pain for adult males is a substernal, crushing pain that radiates down the left arm and up into the jaw. Women and elderly patients with MIs often experience an indigestion-type discomfort and shortness of breath instead of the “typical” substernal pressure.
Infarctions may be classified according to myocardial thickness and the location of affected tissue. Although the majority of MIs occur in the left ventricle, more right ventricular involvement is being recognized. Left ventricular infarctions are classified as inferior (diaphragmatic), anterior, and posterior. Right ventricular infarctions are usually not differentiated by a specific location. Transmural, or Q-wave, infarctions involve 50% or more of the total thickness of the ventricular wall and are characterized by abnormal Q waves and ST-T wave changes. Partial-thickness infarctions (also called subendocardial, nontransmural, and non Q-wave infarcts) are characterized by ST-T wave changes but no abnormal Q waves. Complications of MI include cardiac dysrhythmias, extension of the area of infarction, heart failure, and pericarditis. Rupture of the atrial or ventricular septum, valvular rupture, or rupture of the ventricles can occur as well. Other complications include ventricular aneurysms and cerebral and pulmonary emboli.
Infarctions may occur for a variety of reasons, but coronary thrombosis of a coronary artery narrowed with plaque is the most common cause. Other causes include spasms of the coronary arteries; blockage of the coronary arteries by embolism of thrombi, fatty plaques, air, or calcium; and disparity between myocardial oxygen demand and coronary arterial supply. Multiple risk factors have been identified for coronary artery disease and MI. Some factors—such as age, family history, and gender—cannot be modified. Aging increases the atherosclerotic process, family history may increase the risk by both genetic and environmental influences, and males are more prone to MIs than are premenopausal women. Premenopausal women have the benefit of protective estrogens and a lower hematocrit, although heart disease is on the rise in this population, possibly because of an increased rate of smoking in women. Once women become postmenopausal, their risk for MI increases, as it also does for men over age 50.
Modifiable risk factors include cigarette smoking, which causes arterial vasoconstriction and increases plaque formation. A diet high in saturated fats, cholesterol, sugar, salt, and total calories increases the risk for MIs. Elevated serum cholesterol and low-density lipoprotein levels increase the chance for atherosclerosis. Hypertension and obesity increase the workload of the heart, and diabetes mellitus decreases the circulation to the heart muscle. Hostility and stress may also increase sympathetic nervous system activity and pose risk. A sedentary lifestyle diminishes collateral circulation and decreases the strength of the cardiac muscle. Medications can also prevent risks. Oral contraceptives may enhance thrombus formation, cocaine use can cause coronary artery spasm, and anabolic steroid use can accelerate atherosclerosis.
Nursing care plan assessment and physical examination
Symptomatology is very important in diagnosing MIs. Ask about chest, jaw, arm, and epigastric pain. Remember that not all people have the “typical” chest pain; evaluate the whole clinical picture because some people may experience no pain at all. Ask about shortness of breath, racing heart rate, diaphoresis, clammy skin, dizziness, nausea, and vomiting. Note that sudden death and full cardiac arrest may be the first indication of MI.
Elicit a thorough description of the symptoms by using the P, Q, R, S, T approach. P stands for palliative or precipitating measures (what was occurring when the symptoms began and what made the symptoms better or worse). Q is the quality of the discomfort (sharp, stabbing, or pressure). R represents radiating; S is the severity of the discomfort on a scale such as one from 1 to 10. T stands for time since symptoms and discomfort began. The time is very important because increased time to treatment may mean increased muscle damage; time to treatment dictates management. The timing or asking these questions is also important. If the patient is in acute distress, ask the minimum number of question that are necessary to treat the pain effectively and ask the additional questions later.
The patient with an MI usually appears acutely ill with diaphoresis, clammy skin, nausea and vomiting, and shortness of breath, but the patient may have mild symptoms such as epigastric discomfort. When you inspect the patient, note the respiratory status, including rate, depth, rhythm, and effort. Observe the patient’s skin for color and diaphoresis, and observe the mental status for confusion, dizziness, and anxiety. When you auscultate the patient’s heart, you may hear heart sounds that are irregular if dysrhythmias are present—an S3 if irregular ventricular filling occurs, and an S4 if irregular atrial filling occurs. A murmur may be heard if the valves are not closing tightly because of ischemia or injury of the papillary muscle.
Inquire about stressors in the patient’s life and how the patient deals with them. A diagnosis of heart disease and MI is a life-changing event that carries emotionally laden concerns for most patients. Also assess the patient’s ability to cope with a sudden illness and the change in roles that an MI involves.
Nursing care plan primary nursing diagnosis: Altered tissue perfusion (myocardial) related to narrowing of the coronary artery(ies) associated with atherosclerosis, spasm, or thrombosis.
Nursing care plan intervention and treatment plan
The physician usually prescribes oxygen therapy, often at 2 to 4 L/min to provide increased oxygen to the myocardial tissue. If it has been less than 4 to 6 hours since pain began, and if the clinical picture suggests an MI, thrombolytic agents may be given to dissolve the coronary thrombus. A cardiac catheterization may be performed when the patient’s condition is stable to identify the areas of blockage in the coronary arteries and to assist in determining treatment. Medical treatment with medications as described here may be the treatment of choice if the blockage is extensive and if the patient has conditions that increase mortality or morbidity with surgery. A percutaneous transluminal coronary angioplasty (PTCA) may be performed if the blockages are limited and are accessible with a balloon catheter. The cardiologist inflates the balloon catheter at the area of blockage and compresses the plaque or pushes the arterial wall out to enlarge the arterial lumen. The cardiologist may also place a stent at the area of dilation to maintain patency. An arthrectomy, which involves shaving off the plaque in the coronary artery and removing the debris to obtain arterial patency, in another nonsurgical option.
Continuous cardiac monitoring, along with intermittent 12-lead electrocardiograms, helps the healthcare team monitor the resolution of ischemic and injured areas. Hemodynamic monitoring may be initiated, and a flow-directed pulmonary artery catheter may be used to measure filling pressures in the ventricles, to determine pulmonary artery pressures, and to calculate the cardiac output. Notify the physician for significant signs of decreased cardiac output, such as hypotension, diminished urine output, crackles in the lungs, cool and clammy skin, and fatigue.
The surgical option for patients with coronary blockages caused by plaque is coronary artery bypass grafting (CABG). To restore blood flow to the heart muscle distal to the blockages, the surgeon uses the left internal mammary artery or the saphenous vein to bypass the areas of blockage within the coronary arteries.
Diet restrictions begin in the hospital and should be continued at home. A collaborative effort among the patient, dietician, physician, and nurse plans for a diet low in cholesterol, fat, calories, and sodium (salt). Drinks in the coronary care unit are usually decaffeinated and not too hot or cold in temperature, although some experts question the need to restrict extremes of temperature. Foods with fiber may decrease the incidence of constipation.
The focus is to control pain and related symptoms, to reduce myocardial oxygen consumption during myocardial healing, and to provide patient/family education. Remember that chest pain may indicate continued tissue damage; therefore, manage chest pain immediately. In addition to the pharmacologic methods mentioned here, a variety of measures can be used to reduce the cardiac workload during periods of chest pain. To decrease oxygen demand, encourage the patient to maintain bedrest for the first 24 hours; encourage rest throughout the entire hospitalization. Create a quiet, restful environment and encourage family involvement in the patient’s care. Discourage any straining such as Valsalva’s maneuver.
Because anxiety and fear are common among both patient and families, encourage everyone to discuss their concerns and express their feelings. Use a calm, reassuring voice; give simple explanations about care and procedures; and stay with the patient during periods of high anxiety if possible. Discuss with the patient and family the diagnosis, the activity and diet restrictions, and medical treatment. Numerous lifestyle changes may be needed. A cardiac rehabilitation program is helpful in limiting risk factors and in providing additional guidance, social support, and encouragement. The goals of a cardiac rehabilitation program are to reduce the risk of another MI through re-education and implementation of a secondary prevention program and to improve the quality of life for the MI victim. The program provides progressive monitored exercise, additional teaching, and psychosocial support. An exercise stress test is used before beginning exercise to evaluate the patient’s response to physical activity and to determine an appropriate program. There are usually three phases to cardiac rehabilitation: in hospital, outpatient, and follow-up.
Nursing care plan discharge and home health care guidelines
Be sure the patient understands all the medications, including the dosage, route, action, and adverse effects. Instruct the patient to keep the nitroglycerin bottle sealed and away from heat. The medication may lose its potency after the bottle has been opened for 6 months. If the patient does not feel a sensation when the tablet is put under the tongue or does not get a headache, the pills may have lost their potency.
Explain the need to treat recurrent chest pain or MI discomfort with sublingual nitroglycerin every 5 minutes for three doses. If the pain persists for 20 minutes, teach the patient to seek medical attention. If the patient has severe pain or becomes short of breath with chest pain, teach the patient to take nitroglycerin and seek medical attention right away. Explore mechanisms to implement diet control, an exercise program, and smoking cessation if appropriate.
No comments:
Post a Comment