<prompt> Causes of cynosls-TOFPDATricuspid atresiaEisonmengers complex  <response>: Tetralogy of Fallot causes low oxygen levels in the blood. This leads to cyanosis a bluish-purple color to the skin. The classic form includes four defects of the hea and its major blood vessels: Ventricular septal defect hole between the right and left ventricles Ref Davidson 23rd edition pg 455 