A mechanical heart valve apparatus includes a loop-shaped frame defining a valve opening and formed with a pair of transverse slot units and a pair of longitudinal slots and a pair of valve plates mounted on the loop-shaped frame. Each of the valve plates includes a pair of first studs that are slidably and respectively inserted into the transverse slot units, and a second stud that is slidably inserted into a respective one of the longitudinal slots. The valve plates are pivoted to each other so as to be rotatable relative to each other between a closed position, in which the second studs are disposed adjacent to upper ends of the longitudinal slots, and an opening position, in which the second studs are disposed adjacent to lower ends of the longitudinal slots.
