A 3-week old female is scheduled for palliative repair of tetralogy of Fallot. She is currently receiving an infusion of prostaglandin. Which of the following agents, given at standard clinical doses, WILL affect the direction of flow through her current shunt?
a) Isoflurane
b) Pancuronium
c) Propofol
d) Ketamine
e) Fentanyl
Answer c. Palliative repair of tetralogy of Fallot involves placement of a modified Blalock-Taussig shunt. This replaces the ductus arteriosus which is maintained by an infusion of prostaglandin. Flow through either shunt will be determined by balance of SVR and PVR and those drugs that affect one more than the other will affect the direction of flow. In normal doses, pancuronium, isoflurane, sevoflurane, ketamine and opiates do not affect the shunt direction, unlike propofol which can decrease SVR significantly, reverse shunt flow and result in worsening cyanosis.