Book
The Procedural Work For Cardiac Diseases
- Myocardial Infarction (MI)
What is Myocardial Infarction?
Myocardial infarction (MI) is a term synonymous with coronary artery occlusion and heart attack, but the term "myocardial infarction" is preferred because myocardial ischemia leads to Acute Coronary Syndrome (ACS), which can result in the death of heart muscle cells.
In myocardial infarction, a portion of the heart muscle is permanently damaged due to the rupture of atherosclerotic plaques and the formation of blood clots, resulting in a complete blockage of the artery. The ranges of Acute Coronary Syndrome (ACS) include unstable angina, non-ST elevation myocardial infarction (NSTEMI), and ST-elevation myocardial infarction (STEMI).
Pathophysiology:
In all cases of myocardial infarction, there is a significant imbalance between the supply of oxygen to the heart muscle and its demand.
- Unstable Angina: There is reduced blood flow in the coronary artery, often due to the rupture of atherosclerotic plaques, but the artery is not completely blocked.
- Progression to Infarction: When cells are deprived of oxygen, ischemia occurs, leading to cell injury. Oxygen deprivation causes infarction or damage to the cells.
Causes:
The causes of myocardial infarction primarily involve the blood vessels.
- Vascular Spasm: This refers to a sudden constriction or narrowing of the coronary artery.
- Decreased Oxygen Supply: This occurs due to acute blood loss, anemia, or low blood pressure.
- Increased Oxygen Demand: This can be caused by a rapid heart rate, thyroid toxicity, or cocaine use.
Clinical Symptoms:
Some patients may have prior symptoms or a history of coronary artery disease, but about half of them report no prior symptoms.
- Chest Pain Location: Chest pain is the main symptom of myocardial infarction. It is characterized by persistent, crushing pain beneath the sternum, which may radiate to the left arm, jaw, neck, or shoulder blades. The pain is often described as heavy, pressing, or crushing and may last for more than 12 hours.
- Shortness of Breath: Occurs due to increased oxygen demand and reduced oxygen supply.
- Indigestion: Results from the stimulation of the nervous system.
- Tachycardia and Tachypnea: To compensate for the lack of oxygen supply, the heart rate and breathing rate increase.
- Catecholamine Response: The patient may experience cold extremities, sweating, anxiety, and tension.
- Fever: It rarely occurs in the early stages of myocardial infarction, but a slight increase in temperature may appear in the following days.
Evaluation and Diagnostic Methods:
- The diagnosis of myocardial infarction (MI) is generally based on the clinical symptoms.
- Patient History: Includes the current symptoms, a history of previous heart disease, and any other relevant illnesses, as well as a family history of heart disease.
- Electrocardiogram (ECG):
- ST-segment elevation indicates ischemia.
- T-wave elevation or inversion indicates injury.
- Q-wave development suggests prolonged ischemia or cell death.
- Cardiac Enzymes and Isoenzymes:
- CPK-MB (Cardiac Isoenzyme): Rises within 4-8 hours, peaks at 12-20 hours, and returns to normal within 48-72 hours.
- LDH: Rises within 8-24 hours, peaks within 72-144 hours, and may take up to 14 days to return to normal. A ratio of LDH1 higher than LDH2 (inverted ratio) is a helpful marker for confirming myocardial infarction if not detected in the acute phase.
- Troponin: Troponin I (cTnI) and Troponin T (cTnT): Levels rise within 4-6 hours, peak at 14-18 hours, and return to normal within 6-7 days. These enzymes are more specific for cell damage and are useful in diagnosing myocardial infarction after surgeries where CPK-MB may rise due to skeletal muscle injury.
- Myoglobin: A small molecular weight heme protein that is rapidly released from damaged muscle tissues. It rises within 2 hours after acute myocardial infarction and peaks between 3-15 hours.
- Electrolytes and Minerals: Imbalance of sodium and potassium may alter electrical conduction and impair the heart's contractility.
- White Blood Cells (WBC): Leukocytosis (10,000-20,000 WBC) usually appears on day 2 after myocardial infarction due to inflammation.
- Erythrocyte Sedimentation Rate (ESR): Elevated on day 2 or 3 after myocardial infarction, indicating an inflammatory response.
- Arterial Blood Gases (ABGs) / Pulse Oximetry: May indicate hypoxia or acute/chronic pulmonary pathologies.
- Lipids (Total Cholesterol, HDL, LDL, VLDL, Total Triglycerides, Phospholipids): Elevated levels may reflect atherosclerosis as a cause of coronary artery narrowing or spasm.
- Chest X-ray: May be normal or show cardiac enlargement, indicating heart failure or ventricular dilation.
- 2D Echocardiogram: Can be performed to assess the dimensions of the cardiac chambers, wall motion, ejection fraction (EF), and valve function.
- Nuclear Imaging Studies: Persantine or Thallium imaging assesses blood flow to the myocardium and myocardial cell status, such as the location/extent of acute or prior myocardial infarction.
- Cardiac MRI / MUGA (Multi-Gated Acquisition Scan): Assesses global and regional ventricular function, wall motion, and ejection fraction.
- Coronary Angiography: Shows coronary artery narrowing or occlusion and is often performed alongside left ventricular pressure measurement and assessment of left ventricular function (EF). This procedure is usually not done in the acute phase of myocardial infarction unless emergency coronary artery repair or cardiac surgery is imminent.
- Digital Subtraction Angiography (DSA): A technique used to visualize coronary bypass grafts and detect peripheral artery diseases.
- Magnetic Resonance Imaging (MRI): Provides images of blood flow, heart chambers, ventricular septum, valves, vessels, plaque formation, and infarcted tissue, as well as thrombus locations.
- Stress Test: Determines the cardiovascular response to physical activity (often performed with thallium imaging during recovery).
This comprehensive diagnostic approach helps in early identification and management of myocardial infarction, reducing complications and improving patient outcomes
Medical Treatment:
The medical treatment of angina aims to reduce heart muscle damage, maintain heart function, and prevent complications .
Pharmacological Treatment
- Morphine: Morphine is administered intravenously to treat Myocardial Infarction (MI) with the goal of reducing pain and anxiety.
- Angiotensin-Converting Enzyme (ACE) Inhibitors: These inhibitors block the conversion of angiotensin I to angiotensin II, reducing blood pressure and encouraging the kidneys to excrete sodium and fluids, thus decreasing the oxygen demand in the heart.
- Thrombolytic Drugs: These medications dissolve the clot in the coronary artery, allowing blood to flow again through the artery, reducing the size of the infarction and preserving ventricular function.
Emergent Percutaneous Coronary Intervention (PCI)
- This procedure is used to open a blocked coronary artery and enhance reperfusion to the area deprived of oxygen.
- PCI may also be recommended for patients with unstable angina and non-ST elevation myocardial infarction (NSTEMI), especially for those at high risk due to continuous ischemia.
Nursing Care for Myocardial Infarction (MI)
Nursing care for individuals with myocardial infarction is crucial and systematic, requiring efficient delivery of care to the patient.
Nursing Assessment
Assessment is one of the most important aspects of patient care for those with myocardial infarction.
- Assessment of chest pain that does not resolve with rest or medication.
- Monitoring vital signs, especially blood pressure and heart rate.
- Assessment for signs of dyspnea, rapid breathing, and the presence of crackles in the lungs.
- Evaluation of nausea and vomiting.
- Monitoring of urine output for any decrease.
- Reviewing the patient’s medical history.
- Performing a thorough physical assessment to identify complications and changes in the patient's condition.
- Ongoing assessment of venous access sites.
Nursing Diagnosis
Based on clinical symptoms, medical history, and diagnostic assessment data, the main nursing diagnoses may include:
- Impaired tissue perfusion in the heart due to decreased coronary blood flow.
- Risk of impaired peripheral tissue perfusion due to decreased cardiac output from left ventricular dysfunction.
- Deficient knowledge related to self-care following myocardial infarction.
Planning and Goals
The goal of nursing care planning is to establish objectives that aim for the best possible health outcomes for the patient, such as reducing pain, improving heart function, and increasing the patient’s knowledge about self-care after the infarction.
To create a care plan, the focus should be on the following:
- Alleviating pain or signs and symptoms of ischemia.
- Preventing heart muscle damage.
- Ensuring adequate respiratory function.
- Maintaining or achieving sufficient tissue perfusion.
- Reducing anxiety.
- Preventing or early detection of complications.
- Relieving/controlling chest pain.
- Ensuring adequate heart rate/rhythm to maintain sufficient cardiac output and tissue perfusion.
- Achieving a level of activity sufficient for basic self-care.
- Reducing/Managing anxiety.
- Understanding the disease process, treatment plan, and prognosis.
- Developing a plan to address post-discharge needs.
Nursing Priorities
- Pain and anxiety relief.
- Reducing the workload on the heart.
- Prevention/early detection and management of arrhythmias or life-threatening complications.
- Promoting heart health and self-care.
Nursing Interventions:
Nursing interventions must be based on the goals outlined in the nursing care plan.
- Oxygen Administration with Medication: To help alleviate symptoms and ensure adequate tissue oxygenation.
- Encourage Bed Rest with Elevated Backrest: To reduce chest discomfort and ease breathing difficulties.
- Encourage Frequent Position Changes: To prevent fluid accumulation at the lung bases.
- Frequent Monitoring of Skin Temperature and Peripheral Pulses: To assess tissue perfusion and detect early signs of poor circulation.
- Provide Information in a Clear, Supportive, and Honest Manner: To help the patient understand their condition and the necessary interventions.
- Close Monitoring for Changes in Heart Rate, Rhythm, Heart Sounds, Blood Pressure, Chest Pain, Respiratory Status, Urine Output, Skin Color, and Lab Values: To detect early changes in the patient's condition that may require intervention.
Evaluation:
After implementing the interventions as per the schedule, the nurse should verify:
- Absence of Pain or Signs and Symptoms of Ischemia (tissue oxygen deprivation).
- Prevention of Further Myocardial Damage (Heart Muscle Injury).
- Absence of Respiratory Dysfunction.
- Adequate Tissue Perfusion Maintained.
- Reduced Anxiety Level.
Discharge Guidelines and Home Care:
The most effective way to ensure that a patient follows their self-care plan after discharge is to identify their priorities.
1. Education:
- Cardiac Health Education: Educating the patient about maintaining a heart-healthy lifestyle is crucial. This includes managing risk factors like diet, exercise, and smoking cessation.
2. Home Care:
- Assist with Scheduling Follow-up Appointments: Help the patient schedule and adhere to follow-up appointments for ongoing evaluation of their heart condition.
- Cardiac Rehabilitation: Ensure that the patient follows the prescribed cardiac rehabilitation program.
3. Monitoring and Follow-up:
- Regular Monitoring: The nurse should remind the patient about regular monitoring including lab tests, ECGs, and general health check-ups to ensure early detection of complications.
4. Adherence to Medications and Diet:
- Monitor Adherence to Prescribed Diet and Medications: Ensure that the patient adheres to dietary restrictions and medication schedules as prescribed by the healthcare provider.
Documentation Guidelines:
To ensure all actions are documented correctly, the following should be documented:
- Individual Outcomes
- Vital Signs, Heart Rhythms, and Arrhythmias
- Care Plan Details
- Education Plan
