Bjork-Shiley (Tilting disc) 27 mm
Peak gradient:	10 ± 4 mmHg
Mean gradient:	5 ± 2 mmHg
Peak velocity:	1.6 ± 0.49 m/s
Pressure half-time:	89 ± 28 ms
Effective orifice area:	1.81 ± 0.54 cm2