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: Anaesthesia
Anaesthetic agent of choice in congenital heart disease with right to left shunt is 
Select and explain. 
A. Thiopentone, B. Propofol, C. Etomidate, D. Ketamine
D: Ketamine
Answer: D: Ketamine 
Explanation: Ketamine being sympathomimetic causes raised left sided pressures, which obstructs shunt flow.