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
[{'content': 'Pulsus alternans is seen in: March 2009 \nSelect and explain. \nA. MS with MR, B. AS with AR, C. Left ventricular failure, D. Digitalis poisoning', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C: Left ventricular failure Pulsus alternans is a physical finding characterized by a regular alternation of the force of the aerial pulse. It almost invariably indicates the presence of severe left ventricular systolic dysfunction.', 'role': 'assistant'}]