Myocardial infarction is a term that is used in the clinical setting in reference to the necrosis of a section of the myocardium which occurs as a result of the interruption of the supply of blood to the heart. This often takes place as a result of the occlusion of the coronary artery. From a pathological point of view, myocardial infarction is myocardial infarction refers to the death of the myocardial cells as a result of prolonged ischemia. It may the result of chronic heart disease or as the onset of coronary heart disease.
The prolonged ischemia which triggers the death of myocardial cells is often identified from the history of the patient and from the ECG. The symptoms of ischemia associated with myocardial infarction in include: discomfort in the chest, upper extremity, jaw and epigastrium discomfort. The discomfort is often accompanied by diaphoresis, dyspnea, diaphoresis and syncope. This may take about 20 minutes. The symptoms are not just limited to myocardial infarction hence it is common for the symptoms to be attributed to neurological, pulmonary, musculoskeletal or gastrointestinal disorders.
Myocardial infarction can be classified as acute, healed or healing. The presence of polymorphonuclear leukocytes is often an indication of myocardial infarction. Healing infarction is characterized by the absence of polymorphonuclear leukocytes and the presence of fibroblasts and mononuclear cells. The presence of scar tissue without cellular infiltration is indicative of healed myocardial infarction. Coronary heart disease which is one of the causes of myocardial infarction has been on a steady decline in the United States of America. In 2010, the prevalence of coronary heart diseases in persons who were older than 65 years was 19.8% while among those who were aged between 45- 64 years was 7.1%. The prevalence among those who are aged between 18 and 44 years is 1.2%.
The diagnosis of myocardial infarction can be done through the following methods: the electrocardiogram is critical in the diagnosis of myocardial infarction. Acute myocardial infarction can be diagnosed based on the deviations of the ST-T and Q waveforms. The prognosis, the portion of myocardium that is at risk, the time the infarction took place and the form of therapy that can be used deduced from ECG. A more severe form is diagnosed on the basis of the profoundness of the shift in the ST segment of the ECG. The loss of the amplitude of the R wave, intraventricular and artioventricular delays in conduction and arrhythmias are some of the other signs that are associated with acute myocardial infarction. However, ECG readings observed during acute myocardial infarctions are also observed in other conditions such as cardiomyopathy, acute pericarditis, left ventricular hypertrophy, Brugada syndrome and early repolarization syndrome. In the absence of other conditions ST elevations at the J point with the cut -off point of = 0.2 mV for men and =0.15 mV for women in leads V2 and V3 in addition to T inversion =0.1 mV two contiguous leads with a prominent wave or down sloping =0.5 mV in two contiguous leads are regarded as manifestations of acute myocardial infarctions.
The readings are therefore used together with ECG tracings in the diagnosis of myocardial infarctions. Some of the pitfalls that are associated with ECG in the diagnosis of myocardial infarctions are false positives and negatives. False positives could be associated with lead transposition, cholecystitis, pulmonary embolism, subarachnoid haemorrhage, persistent juvenile pattern, pre excitation, early repolarization and poor position of the precordial ECG electrodes. False negatives could be as a result of persistent ST elevation as a result of previous myocardial infarction.
The rise in the levels of biomarkers such as troponin in addition to evidence of ischemia is also used in the diagnosis of myocardial infarction. Cardiac troponin 1 or T is often preferred biomarker in the diagnosis of myocardial infarction given that it is highly specific and sensitive. Even minute levels of necrosis in the myocardium trigger changes in the levels of cardiac troponin 1 or T. Echocardiography is used in the diagnosis of the complications that arise from acute myocardial infarctions such as the mitral regurgitation due to ischemia or rupture of the papillary muscle, the rupture of the myocardial free wall rupture and acute ventricular septal defect. This technique is particularly important in the prediction of infarctions for patients with a non- diagnostic ECG. High resolution magnetic resonance imaging with contrast can be used in the detection of areas of fibrosis that represent a prior myocardial infarction.
The chest pains reported by the patient at the time of hospitalization aid in making a diagnosis. The nurse can diagnose whether the chest pain is as a result of a myocardial infarction on the basis of the duration, the location, the intensity and the quality. In addition to chest pain symptoms such as palpitations, fatigue, shortness of breath and fever are also used by the nurses in making a diagnosis. They point to interrupted flow of blood to the heart as is characteristic in myocardial infarctions. The nurse can also rely on information of familial history and patient history in making the diagnosis. A history of cardiac problems is likely to be repeated in a patient’s life. In addition to this, predisposition to a myocardial infarction increases if the family members have heard cardiac problems.
During the hospital stay, the patient should be given antipyretics such as acetaminophen in order to suppress or arrest the development of fever within 24 to 48 hours of the infarction and the subsequent tachycardia. For patients who do not have a previous history of hypotension, ACE inhibitors are often recommended for long term therapy. It is recommended that the administration of the inhibitors is initiated 24 hours after the infarction. Beta adrenergic blockers are also recommended for long term therapeutic use and ought to be administered 4 hours after the onset of pain. Patients with hypotension, shock, elevated levels of intracranial pressure ought to be given prophylaxis for stress ulcers at 6 to 12 hour intervals.
It is critical for the nurse to carry out assessment of the patient not only during the period of the hospital stay but also beyond that. This entails the following: the nurse assesses and monitors the chest pains that are experienced by the patient. It is also critical for the patient to be relaxed while undergoing treatment in order to allow for accurate ECG readings to be undertaken. The levels of magnesium and potassium ought to be monitored in order to be determined so as to prevent the occurrence of arrhythmias. The assessment of the ST segment of the ECG ought to be done often in order to determine whether the patient is experiencing silent or recurrent ischemia. The nurse also assesses the patient for signs of heart failure such as pedal edema, increased jugular venous pressure and crackles.
Once the patient has been treated and is ready to discharged, he or she ought to be taught on management of the condition. One of the critical elements that the nurse ought to teach the patient about is the importance of diet. Low fat diets that are comprised on lots of vegetables, low amounts of carbohydrates and proteins are important for a patient who is recovering from a myocardial infarction in order to keep their cholesterol levels at reasonable levels. The patient should also be encouraged to include fiber in their diet in order to aid digestion in addition to lowering their intake of saturated fats and cholesterol. The patient should also be encouraged by the nurse to participate in moderate forms of exercise such as walking briskly, cycling and jogging for a period of between 30 and 60 minutes each day. If the patient is a heavy smoker or drinker, the nurse should recommend that the patient desist from these habits given that they increase the risk of the recurrence of a myocardial infarction. The family should also be encouraged to avoid smoking in the presence of the patient in order to avoid exposing the patient to second hand smoke. The patient needs to be taught by the nurse to watch out for signs of another infarction hence should they worsen, he or she can call emergency medical services hence minimize the damage. The patient ought to be take one nitroglycerin dose each day sublingually in order to relieve the chest pain. The family members should also be taught to be on the lookout for the symptoms and be prepared to take the patient to hospital in the event of a recurrence. The family should also be trained on cardiac resuscitation by the nurse so as to prepare them to adequately respond in case the patient has infarctions in the future.
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