A study of discharge coefficient in bileaflet valves

The measurement of a cardiac valve´s area is a common procedure, usually performed with noninvasive, Doppler-based techniques. Such measurements are not, however, without problems: a potential source of errors is the value of a valve´s discharge coefficient. In-vitro pressure and flow measurements relative to the bileaflet valve of four brands were performed. A total of 12 valve samples was studied to cover the entire range of valve sizing. The data were used in the Gorlin formula for valve area measurements, and the dependence of the discharge coefficient on the internal diameter of the valve and the flow rate was accurately determined. The reported results can be used in a great number of follow-up clinical assessments to improve the accuracy of valvular orifice measurements.