Myocardial infarction is a condition in which myocardial tissue is abruptly and severely deprived of oxygen. It can lead to necrosis of myocardial tissue if blood flow is not restored.
Physical changes in the heart do not occur until 6 hours after the infarction, the infarcted area becomes blue and swollen, and yellow and gray after 48 hours. By 8-10 days, granulation tissues form, and develop into scar over 2-3 months.
There are three location of
Myocardial Infarction:
- Anterior or septal MI or both: due to obstruction of the left anterior descending.
- Posterior wall MI or lateral wall MI: due to obstruction of circumflex artery.
- Inferior MI: due to obstruction of the right coronary artery
Risk Factors of Myocardial Infarction:- Coronary artery disease
- Atherosclerosis
- Smoking
- Elevated cholesterol levels
- Hypertension
- Obesity
- Impaired glucose tolerance
- Stress
- Physical inactivity
Diagnostic Procedures for MI:
- Total Creatine Kinase Level: rises with 3 hours and peaks within 24 hours
- CK-MB isoenzyme: peaks within 18-24 hours after the onset of chest pain and returns to normal 48-72 hours later
- Troponin level: rises within 3 hours and remains elevated up to 7 days
- Myoglobin: rises within 1 hour, peaks in 4-6 hours, and returns to normal within 24-36 hours
- LDL level: rises 24 hours after MI, peaks 48-72 hours, and normal in 7 days
- White blood cell count: elevated WBC on 2nd day of MI
- Electrocardiogram: ST segment elevation, T wave inversion, and abnormal Q wave
Signs and Symptoms of MI:
- Pain: crushing substernal pain, radiate to the jaw, back and left arm. Pain occurs without any causes primarily early morning and unrelieved by rest or nitroglycerin and last 30 minutes or longer.
- Diaphoresis
- Nausea and vomiting
- Dysrhythmias
- Dyspnea
- Feeling of fear and anxiety
- Pallor, cyanosis, coolness of extremities
Complication of MI:
- Heart failure
- Dysrhythmias
- Pulmonary edema
- Thrombophlebitis
- Cardiogenic shock
- Pericarditis
- Mitral valve insufficiency
- Ventricular rupture
- Postinfarction angina
Intervention in Acute Stage:
- Assess a description of the chest pain
- Assess vital sign
- Assess and monitor cardiovascular status
- Administer oxygen at 2-6 L/min by nasal cannula
- Establish IV access
- Administer nitroglycerin as prescribed
- Administer morphine sulfate as prescribed (if unresponsive to nitroglycerin)
- Obtain a 12-lead ECG
- Administer IV nitroglycerin and antidysrhythmias as prescribed
- Monitor thrombolytic therapy
- Monitor for signs of bleeding
- Administer beta blocker as prescribed
- Monitor for cardiac dysrhythmias
- Monitor for complication of Myocardial infarction
- Assess and monitor distal peripheral pulses and skin temperature
- Monitor intake and output
- Assess respiratory rate and breath sounds
- Monitor blood pressure closely
Intervention Following Acute Stage:
- Bed rest for the first 24-36 hours, allow patient to stand to void or use a bedside commode
- Provide range of motion exercises
- Monitor the complication of MI
- Encourage patient to verbalize feeling.
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