This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
A patient with inferior wall myocardial infarction is in shock. The reason is: September 2008 
Select and explain. 
A. Right ventricular infarction, B. Mitral regurgitation, C. Infarction causing septal defect, D. Decreased ejection fraction from left ventricle
A: Right ventricular infarction
Answer: A: Right ventricular infarction 
Explanation: Ans. A: Right ventricular infarction Acute myocardial infarction (MI) involving only the right ventricle is a rare event. Much more commonly, right ventricular infarction is associated with infarction of the inferior wall of the left ventricle, occurring in more than one-third of such cases. In such patients, the infarction typically involves the left ventricular inferior-posterior wall, septum, and posterior right ventricular free wall. A right ventricular infarct should be considered in all patients who present with an acute inferior wall myocardial infarction, especially in the setting of a low cardiac output. Patients may describe symptoms consistent with hypotension. Other presentations include high-grade atrioventricular block, tricuspid regurgitation, cardiogenic shock, right ventricular free wall rupture, and cardiac tamponade.