Tetralogy of Fallot is a congenital cardiac malformation that consists of an interventricular communication, also known as a ventricular septal defect, obstruction of the right ventricular outflow tract, override of the ventricular septum by the aortic root, and right ventricular hypertrophy.

A condition characterized by obstruction of the airway and by pauses in breathing during sleep occurring many times during the night. Obstructive sleep apnea is related to a relaxation of muscle tone (which normally occurs during sleep) leading to partial collapse of the soft tissues in the airway with resultant obstruction of the air flow.