Tricuspid Valve Atresia

Rarely occurring, complete absence of the tricuspid valve, instead an impermeable membrane is created.

http://www.brainshark.com/cryolife/vu?pi=zHCzlTcW3zY1lRz0 _{(Copyright Cryolife, https://www.cryolife.com)}

https://en.wikipedia.org/wiki/Tricuspid_atresia _([1])