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': 'For the management of intraoperative myocardial ischaemia, all of the following are advised except \nSelect and explain. \nA. Heparin, B. Intravenous nitroglycerine, C. Calcium channel blocker, D. Atropine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]