A 5-year-old child with Tetralogy of Fallot develops a hypercyanotic spell ('tet spell') in the emergency department. Which drug is used acutely to reduce right ventricular outflow tract infundibular spasm by a prostaglandin-independent mechanism?

• A Misoprostol
• B Morphine
• C Prostaglandin E1
• D Phenylephrine ✓

Explanation

Phenylephrine, an alpha-1 agonist, increases systemic vascular resistance (afterload), which reduces the right-to-left shunt and forces more blood through the pulmonary outflow tract, relieving the hypercyanotic spell. This is a prostaglandin-independent mechanism. Prostaglandin E1 keeps the ductus arteriosus patent, which is unrelated. Misoprostol is a PGE1 analogue used for ulcer protection, not tet spells.

Reference: :

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.