A 55-year-old man with a history of hypertension and type 2 diabetes presents with sudden onset of chest pain radiating to his left arm. ECG shows ST-segment elevation in leads II, III, and aVF. His blood pressure is 88/60 mmHg, and his heart sounds reveal a soft systolic murmur at the left lower sternal border. What is the most likely cause of his hypotension? A) Cardiogenic shock due to left ventricular failure B) Right ventricular infarction C) Aortic dissection D) Pericardial tamponade E) Pulmonary embolism Correct Answer: B) Right ventricular infarction Explanation: ST-elevation in leads II, III, aVF = Inferior MI Hypotension + Inferior MI → Consider right ventricular infarction Soft systolic murmur suggests tricuspid regurgitation due to RV dysfunction Diagnosis: Right-sided ECG (ST-elevation in V4R) A) Cardiogenic shock → Incorrect. Would be due to LV failure, not RV infarction. C) Aortic dissection → Incorrect. Would present with severe tearing chest pain radiating to the back + widened mediastinum on CXR. D) Pericardial tamponade → Incorrect. Would have pulsus paradoxus, distant heart sounds, electrical alternans. E) Pulmonary embolism → Incorrect. Would have sudden dyspnoea, tachycardia, and right heart strain on ECG (S1Q3T3 pattern). Key Tips for PLAB 1: ✅ Inferior MI + hypotension = Suspect RV infarction. ✅ Treatment: IV fluids (avoid nitrates/diuretics, which worsen hypotension). ✅ Confirm with right-sided ECG (ST-elevation in V4R).
