ScienceContemporaryglobalhigh confidence

A rare congenital heart valve condition called a quadricuspid valve occurs when a person is born with four cusps on the aortic valve instead of the usual three.

Notes on verification

Confirmed by multiple independent medical sources including AHA/Circulation and peer-reviewed case reports in PMC, consistently describing quadricuspid aortic valve as a rare congenital defect with four cusps instead of three.

Sources