A 50-year-old male presents with sudden onset of severe epigastric pain, nausea, and vomiting. He denies chest pain. His ECG shows ST elevation in leads II, III, and aVF. His blood pressure is 130/80 mmHg, heart rate 90 bpm, and SpO2 96% on room air. Which of the following findings would be MOST concerning if nitroglycerin were administered?
- AA blood pressure drop to 100/60 mmHg
- BA decrease in heart rate to 70 bpm
- CAn increase in respiratory rate to 20 bpm
- DResolution of epigastric pain
Show answer & explanationAnswer & explanation
Correct answer: A. A blood pressure drop to 100/60 mmHg
The patient's symptoms (epigastric pain, nausea, vomiting) and ECG (ST elevation in II, III, aVF) are classic for an inferior wall myocardial infarction (MI). Inferior MIs often involve the right ventricle, making them preload dependent. Nitroglycerin is a vasodilator that reduces preload. A significant drop in blood pressure (e.g., to 100/60 mmHg or lower) after nitroglycerin in a patient with a right ventricular MI indicates a detrimental effect due to reduced preload and can lead to cardiogenic shock.
Why the other options are wrong
- B. A decrease in heart rate could be a beneficial effect or a benign response, not typically concerning.
- C. An increase in respiratory rate to 20 bpm is within normal limits and not a direct concerning side effect of nitroglycerin in this context.
- D. Resolution of pain is a desired effect of nitroglycerin, indicating it is working.
Inferior MI & Nitroglycerin
Nitroglycerin should be used with extreme caution or avoided in inferior MIs, especially if hypotension is present or develops, due to potential right ventricular involvement and preload dependence.
- Inferior MIs often involve the right ventricle.
- RV MIs are preload-dependent.
- Nitroglycerin reduces preload, risking severe hypotension.
Memory trick: Inferior MI, BP's Low, Nitro's a NO-GO!