Acute Coronary Syndromes: Pathophysiology and Management

Clinical Presentation and Assessment

The classic presentation of ACS is substernal chest pain, often described as "pressure," "heaviness," or "squeezing." However, clinicians must remain vigilant for atypical presentations, which are more common in women, elderly patients, and those with diabetes.

Common Symptoms

• Chest Discomfort: May radiate to the left arm, jaw, neck, or back.
• Dyspnea: Shortness of breath due to decreased cardiac output or pulmonary congestion.
• Diaphoresis: Profuse sweating, often a sign of sympathetic nervous system activation.
• Nausea/Vomiting: Frequently seen in inferior wall infarctions.
• Atypical Signs: Fatigue, epigastric pain, or unexplained anxiety.

Diagnostic Tools

The immediate priority in a suspected ACS case is obtaining a 12-lead ECG and cardiac biomarkers. The ECG allows for the rapid identification of a STEMI, which requires immediate reperfusion therapy.

Nursing Management and Interventions

Nursing care for ACS focuses on stabilizing the patient, reducing myocardial oxygen demand, and preparing for reperfusion therapies.

Immediate Interventions (The "MONA" Concept)

While the order of administration is individualized based on patient assessment, the mnemonic MONA is often used to remember the core components of acute management:

1. Morphine: Used for pain relief and to reduce preload/afterload, thereby decreasing myocardial oxygen demand.
2. Oxygen: Administered if oxygen saturation is low (typically $<94\%$) to ensure adequate supply to ischemic tissues.
3. Nitroglycerin: A vasodilator that reduces preload and dilates coronary arteries to improve blood flow.
4. Aspirin: An antiplatelet agent that prevents further clot formation.

Monitoring and Complications

Once the patient is stabilized, the nurse must continuously monitor for life-threatening complications, most notably dysrhythmias. Ischemic tissue is electrically unstable and can trigger ventricular tachycardia (VT) or ventricular fibrillation (VF).

Worked Example: Clinical Decision Making

Scenario: A 65-year-old male presents to the Emergency Department with crushing substernal chest pain and diaphoresis. His blood pressure is $100/60$ mmHg, and his heart rate is $110$ bpm. The 12-lead ECG shows ST-segment elevation in leads V1 through V4.

Step 1: Identify the ACS Type. The presence of ST-segment elevation indicates a STEMI.

Step 2: Prioritize Interventions. Because this is a STEMI, the priority is "Time is Muscle." The nurse must facilitate immediate reperfusion, such as Percutaneous Coronary Intervention (PCI) or fibrinolytic therapy.

Step 3: Evaluate Safety. The patient's blood pressure is borderline low ($100/60$). The nurse should use nitroglycerin with extreme caution, as further vasodilation could drop the blood pressure significantly, worsening the ischemia.