Your choice: Tetralogy of Fallot
Patients with tetralogy of fallot typically present with cyanosis and clubbing due a to right-to-left intracardiac shunt. A history of hypoxic spells with squatting is common. Squatting increases left ventricular outflow obstruction, or afterload, diminishes the intracardiac right-to-left shunt and, thereby, improves oxygenation.