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Difficulty: MediumCardiovascular System

Paramedics rush a 55-year-old male to the resuscitation bay following the acute onset of crushing substernal chest discomfort that began while he was doing yard work. En route, emergency medical personnel administered chewable aspirin and one dose of sublingual nitroglycerin. Upon arrival, the patient appears ashen and confused. Vital signs reveal a blood pressure of 78/48 mmHg, heart rate of 112/min, and respiratory rate of 18/min. Physical examination demonstrates pronounced jugular venous distention. Pulmonary auscultation reveals clear breath sounds bilaterally without crackles or wheezes. Cardiac auscultation shows a regular, rapid rhythm with no murmurs, rubs, or gallops. A 12-lead electrocardiogram demonstrates 3-mm ST-segment elevations in leads II, III, and aVF. Which of the following is the most appropriate next step in the management of this patient's current hemodynamic state?

  1. A
    Intravenous furosemide administration
  2. B
    Computed tomography angiography of the chest
  3. C
    Intravenous metoprolol administration
  4. Intravenous 0.9% sodium chloride bolusAnswer
  5. E
    Administration of additional sublingual nitroglycerin

Answer

The most appropriate next step is to administer an intravenous 0.9% sodium chloride bolus.
The correct intervention is administering an intravenous isotonic fluid bolus. This patient's clinical presentation (hypotension, elevated jugular venous pressure, clear lungs) and electrocardiogram findings (ST elevation in inferior leads) are classic for a right ventricular myocardial infarction. The right ventricle becomes a passive conduit, making left ventricular filling entirely dependent on elevated central venous pressure. Intravenous fluids optimize this preload and restore systemic blood pressure, especially after it has been compromised by prehospital nitroglycerin administration.

Step-by-Step Solution

1
Analyze the clinical and electrocardiographic findings.
The patient has an acute inferior ST-segment elevation myocardial infarction (STEMI) complicated by right ventricular (RV) involvement, indicated by ST elevations in leads II, III, and aVF, accompanied by elevated jugular venous pressure and clear lungs.
The triad of hypotension, elevated jugular venous pressure, and clear lung fields in the setting of an inferior STEMI is highly specific for right ventricular infarction.
2
Evaluate the patient's hemodynamic response to prehospital medications.
The patient developed profound hypotension (78/48 mmHg) following the administration of sublingual nitroglycerin.
RV infarction causes a sudden decrease in RV contractility. Consequently, pulmonary blood flow and subsequent left ventricular filling become highly dependent on venous return (preload). Nitroglycerin is a potent venodilator that severely reduces preload, precipitating cardiovascular collapse in these patients.
3
Determine the optimal intervention to correct the hemodynamics.
Administer an intravenous fluid bolus.
Increasing intravascular volume with isotonic fluids maximizes right ventricular preload. This augmented volume pushes blood through the pulmonary circulation to maintain left ventricular filling and systemic blood pressure.

Key Concept

Patients with right ventricular myocardial infarction are highly preload-dependent; initial management of hypotension involves cautious intravenous fluid boluses, while preload-reducing medications (nitrates, diuretics) are strictly contraindicated.
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Topics

Cardiovascular System

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