A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 54-year-old man is brought to the emergency department 1 hour after the sudden onset of shortness of breath, epigastric pain, and sweating. He has no history of similar symptoms. He has hypertension and type 2 diabetes mellitus. Current medications include amlodipine and metformin. He has smoked one pack of cigarettes daily for 20 years. He appears weak and pale. His pulse is 56/min, respirations are 18/min, and blood pressure is 100/70 mm Hg. Cardiac examination shows normal heart sounds. The lungs are clear to auscultation. The skin is cold to the touch. An ECG is shown. Bedside transthoracic echocardiography shows normal left ventricular function. High-dose aspirin is administered. Administration of which of the following is most appropriate next step in management?
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A
Intravenous morphineIncorrect. Morphine reduces preload (venodilation) and is contraindicated in RV infarct — it can precipitate cardiogenic shock.
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B
Sublingual nitroglycerinIncorrect. Sublingual nitroglycerin is contraindicated in RV infarct because it reduces preload and can cause severe hypotension; classic NBME pitfall.
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C
Phenylephrine infusionIncorrect. Phenylephrine is a vasopressor but doesn't address the underlying problem (inadequate RV preload); volume expansion is more physiologic.
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D
Normal saline bolusCorrect. RV infarct is preload-dependent; IV fluid bolus restores RV filling and left-sided cardiac output. Avoid nitrates, morphine, and diuretics.
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E
Intravenous metoprololIncorrect. Beta-blockade in RV infarct can precipitate worsening bradycardia and hypotension by reducing both chronotropy and contractility, further compromising RV output dependent on adequate preload and heart rate.
↑ Tap an answer to reveal the reasoning
Answer: D. This patient has an inferior STEMI (ST changes in II, III, aVF) with bradycardia (HR 56) and hypotension (BP 100/70) — strongly suggesting right ventricular infarction. Inferior MIs commonly involve the right coronary artery, which supplies the RV in most people, and ~30-50% of inferior MIs have RV involvement. RV infarction causes the RV to fail as a pump, dropping left-sided preload and cardiac output despite a normal LV.
The key teaching point: in suspected RV infarct, the right ventricle is preload-dependent. Nitroglycerin, morphine, and diuretics all reduce preload and can precipitate severe hypotension or shock — they are contraindicated. The correct first step is an IV normal saline bolus to optimize RV preload and restore left-sided filling. ECG with right-sided leads (V4R) confirms RV involvement; treatment also includes reperfusion (PCI) and avoiding preload-reducing agents.
Clues here pointing to RV infarct: inferior ECG changes, bradycardia (SA node also RCA territory), hypotension despite clear lungs and normal LV function on echo, and cool extremities (poor perfusion). Phenylephrine is a vasopressor and would not address the preload problem; saline does.
**Why each option:**
**A.** Morphine reduces preload (venodilation) and is contraindicated in RV infarct — it can precipitate cardiogenic shock.
**B.** Sublingual nitroglycerin is contraindicated in RV infarct because it reduces preload and can cause severe hypotension; classic NBME pitfall.
**C.** Phenylephrine is a vasopressor but doesn't address the underlying problem (inadequate RV preload); volume expansion is more physiologic.
**D.** Correct. RV infarct is preload-dependent; IV fluid bolus restores RV filling and left-sided cardiac output. Avoid nitrates, morphine, and diuretics.