Myocardial infarction

 

Definition

- Myocardial infarction (MI), commonly known as a heart attack, occurs when there is a sudden blockage of blood flow to a portion of the heart muscle, resulting in tissue damage and potentially life-threatening complications.

Causes:

- Atherosclerosis (narrowing of coronary arteries due to plaque buildup).

- Coronary artery spasm.

- Blood clot (thrombus) formation.

- Coronary artery embolism.

- Coronary artery dissection.

- Drug abuse (e.g., cocaine).

Types:

- **STEMI (ST-segment elevation MI)**: Characterized by a complete blockage of a coronary artery; considered a medical emergency.

- **NSTEMI (Non-ST-segment elevation MI)**: Partial blockage of a coronary artery; also a serious condition but with different management.

Pathophysiology:

- Atherosclerotic Plaque Rupture or Erosion :

  - Plaque in coronary artery ruptures or erodes.

  - Platelets adhere to the injured site, forming a clot.

  - Blood flow is significantly reduced or blocked, leading to ischemia (lack of oxygen).

- Cellular Damage:

  - Heart muscle cells (myocytes) begin to die due to oxygen deprivation.

  - Release of cardiac enzymes (troponin) into the bloodstream.

- Inflammatory Response

  - Inflammation and immune response in the affected area.

  - Scar tissue forms as the heart heals.

Signs & Symptoms:

- Classic Symptoms

  - Severe chest pain or discomfort (crushing, squeezing, or pressure).

  - Pain may radiate to the arm(s), neck, jaw, shoulder, or back.

  - Shortness of breath.

- Additional Symptoms:

  - Profuse sweating.

  - Nausea and vomiting.

  - Feeling lightheaded or faint.

  - Extreme fatigue.

Diagnostic Evaluation:

- Electrocardiogram (ECG/EKG):

 Identifies ST-segment changes and other abnormalities.

- Cardiac Enzyme Blood Tests

(troponin, creatine kinase-MB): Confirm myocardial damage.

- **Coronary Angiography**: Visualizes coronary arteries to identify blockages.

- **Echocardiogram**: Evaluates heart function and wall motion.

- **Chest X-ray**: May reveal heart enlargement or fluid in the lungs.

Pharmacological Management:

- **Thrombolytics**: If STEMI, to dissolve clots and restore blood flow.

- **Antiplatelet medications**: Aspirin, clopidogrel, to prevent further clot formation.

- **Pain relief**: Nitroglycerin for chest pain.

- **Beta-blockers, ACE inhibitors, and statins**: To reduce heart workload and lower cholesterol.

- **Antiarrhythmic medications**: If needed for arrhythmias.

- **Anticoagulants**: Prevent additional clot formation.

Non-Pharmacological Management:

- **Percutaneous Coronary Intervention (PCI)**: Angioplasty with stent placement to open blocked arteries.

- **Coronary Artery Bypass Grafting (CABG)**: Surgical procedure to bypass blocked arteries.

- **Lifestyle modifications**: Healthy diet, smoking cessation, regular exercise, stress management.

Nursing Management with Nursing Diagnosis:

- **Nursing Diagnosis (for acute phase)**: **Decreased Cardiac Output related to myocardial damage and decreased coronary perfusion.**

- Nursing interventions:

  - Continuous monitoring of vital signs and ECG.

  - Administer prescribed medications (e.g., oxygen, nitroglycerin).

  - Emotional support and pain management.

  - Prepare for PCI or CABG if indicated.

  - Education on lifestyle modifications and medication adherence.

Nursing care for MI is critical during the acute phase to manage pain, stabilize the patient, and prepare for interventions to restore blood flow. Rehabilitation and long-term care focus on preventing complications, improving cardiac function, and promoting heart-healthy habits.