Yes, PRECAVA is a Scrabble word!

Letter values in Scrabble US: P 3, R 1, E 1, C 3, A 1, V 4, A 1.

Is it a valid word?

PRECAVA is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

receives blood from the head and arms and chest and empties into the right atrium of the heart; formed from the azygos and both brachiocephalic veins

Also: superior vena cava.