NREMT Paramedic Cognitive ExamCardiology & ResuscitationHard
A 55-year-old male presents with severe epigastric pain, nausea, and vomiting. He denies chest pain. His vital signs are BP 110/70 mmHg, HR 90 bpm, RR 18 bpm, SpO2 97%. A 12-lead ECG shows ST-segment depression in leads V1-V3 and tall R waves in V1. What is the MOST likely cardiac event occurring?
- AInferior wall myocardial infarction.
- BAnterior wall myocardial infarction.
- CLateral wall myocardial infarction.
- DPosterior wall myocardial infarction.
Show answer & explanationAnswer & explanation
Correct answer: D. Posterior wall myocardial infarction.
ST-segment depression in V1-V3 with tall R waves in V1 (and often upright T waves) are classic reciprocal changes indicative of a posterior wall myocardial infarction. This area is not directly visualized by standard 12-lead ECG leads, requiring posterior leads (V7-V9) for direct ST elevation.
Why the other options are wrong
- A. Inferior MI typically shows ST elevation in II, III, aVF.
- B. Anterior MI typically shows ST elevation in V1-V4.
- C. Lateral MI typically shows ST elevation in I, aVL, V5, V6.
Posterior Myocardial Infarction
An infarction affecting the posterior wall of the left ventricle. It is often missed on standard 12-lead ECG as direct ST elevation is not seen in typical leads, but reciprocal changes are present.
- Reciprocal changes: ST depression in V1-V3, tall/broad R wave in V1, dominant R wave in V2.
- Requires posterior leads (V7, V8, V9) for direct ST elevation.
- Often associated with inferior or lateral MI.
Memory trick: Posterior: 'Reciprocal' ST 'Depression' in the 'Anterior' leads!