A 15-year-old boy was diagnosed with mucopolysaccharidosis (MPS) type II and severe aortic valve regurgitation at a local hospital. He was brought to our hospital for further treatment of aortic valve regurgitation. A preoperative cardiac CT scan was ordered to make a definitive diagnosis. Pre-sedation assessment demonstrated that the boy had a difficult airway and severe heart failure, which increased the risk of sedation for the cardiac CT scan. The keys to sedation management during a cardiac CT scan in a child with MPS II include managing the difficult airway and maintaining stable hemodynamics.