Cyanosis
Overview and Ddx for cyanosis: http://lifeinthefastlane.com/resources/cyanosis-ddx/
Podcast on cyanosis based on Core Rosen's and Clinical Knowledge: http://crackcast.org/episode-14-cyanosis/
Considering Tetralogy of Fallot as a possible cause of cyanosis: http://lifeinthefastlane.com/ccc/signs-of-tetralogy-of-fallot/