Objectives\ This study was designed to examine whether proximal isovelocity surface area method(PISA) is better than pressure half time method(PHT) in the measurement of mitral mechanical prosthetic orifice area(MPOA).

• 目的探讨血流汇聚法（pisa法）与压差半降法（PHT法）测量机械二尖瓣口有效开放面积的准确性及可靠性。