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Difficulty: HardInitial Stabilization and Triage

A 62-year-old woman presents to the emergency department due to severe, pressure-like substernal chest pain that began 90 minutes ago. The pain radiates to her jaw and is accompanied by profuse diaphoresis and nausea. Her medical history includes type 2 diabetes mellitus, hyperlipidemia, and osteoarthritis. Vital signs are temperature 36.7°C (98.1°F), blood pressure 80/50 mmHg, heart rate 52/min, respiratory rate 16/min, and oxygen saturation 97% on room air. Physical examination reveals distended jugular veins while sitting at a 45-degree angle. Auscultation of the lungs reveals clear breath sounds bilaterally with no crackles or wheezes. Cardiac auscultation reveals bradycardia with a regular rhythm and no murmurs, rubs, or gallops. The patient's extremities are cool to the touch with faint bilateral pedal pulses. A 12-lead electrocardiogram shows 3-mm ST-segment elevations in leads II, III, and aVF, along with reciprocal ST-segment depressions in leads I and aVL. Which of the following is the most appropriate initial step to stabilize this patient's hemodynamic status?

  1. Immediate volume expansion with 0.9% sodium chlorideAnswer
  2. B
    Sublingual administration of nitroglycerin
  3. C
    Intravenous push of furosemide
  4. D
    Intravenous administration of metoprolol
  5. E
    Emergent transthoracic echocardiography

Answer

Immediate volume expansion with 0.9% sodium chloride
The patient is presenting with an acute inferior myocardial infarction complicated by right ventricular (RV) involvement. This is clinically evidenced by the triad of hypotension, elevated jugular venous pressure, and completely clear lung fields, coupled with the ST-segment elevations in leads II, III, and aVF. RV infarction results in severely impaired right-sided contractility, making the ventricle highly dependent on adequate preload to maintain forward blood flow into the pulmonary circulation and subsequently the left ventricle. The correct initial stabilization step for profound hypotension in this setting is immediate volume expansion with isotonic crystalloids (such as 0.9% sodium chloride) to increase right-sided filling pressures and restore cardiac output.

Step-by-Step Solution

1
Analyze the clinical presentation and electrocardiogram findings.
Identifies an acute inferior ST-segment elevation myocardial infarction accompanied by physical signs of right-sided heart failure (clear lungs, elevated jugular venous pressure, hypotension).
Establishing the specific anatomical location and physiologic state of the infarction is necessary to direct targeted stabilization therapy.
2
Determine the underlying physiological derangement.
Recognizes that the infarcted right ventricle has lost contractility and is strictly dependent on adequate venous return (preload) to push blood into the left heart.
This specific pathophysiology dictates that standard therapies which lower preload will cause severe hemodynamic deterioration.
3
Select the most appropriate initial stabilization step.
Chooses immediate volume expansion with isotonic crystalloid.
Intravenous fluids maximize right ventricular preload, which restores pulmonary blood flow, left ventricular filling, and ultimately systemic blood pressure.

Key Concept

In patients with an acute right ventricular myocardial infarction (characterized by inferior ST-segment elevations, clear lung fields, hypotension, and elevated jugular venous pressure), the infarcted right ventricle relies entirely on high filling pressures. The most urgent stabilization step is preload augmentation via isotonic crystalloid boluses.
Estimated Time:1m 30s
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Topics

Initial Stabilization and Triage

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