Six month postoperative hemodynamics of the Hancock heterograft and the Björk-Shiley prosthesis: results of a Veterans Administration cooperative prospective randomized trial.

In a Veterans Administration Cooperative Study involving 13 medical centers, 575 patients undergoing single valve replacement were prospectively randomized to receive either the standard Björk-Shiley prosthesis or the Hancock porcine heterograft (with a modified orifice for sizes 23 and smaller). The hemodynamic data in the 268 patients who underwent cardiac catheterization an average of 6 months (range 3 to 12) postoperatively are reported. Statistical analyses were performed on valve sizes 23, 25 and 27 in the aortic position, and 29, 31 and 33 in the mitral position. A wide variation was observed in mean pressure gradient and calculated orifice area in both valve types within all sizes in both the aortic and the mitral positions. In the aortic position, the Björk-Shiley prosthesis tended to have a lower pressure gradient and larger calculated orifice area than the Hancock heterograft, but the differences in gradient between the two valve types were significant only in the larger-sized valves. The difference in calculated area between the two valve types was not significant within each valve size. In the mitral position, there were no differences in gradient and calculated orifice area between the two types of prostheses. The postoperative cardiac index, regurgitant volume, pulmonary artery systolic and mean pressures, left ventricular end-diastolic pressure, left ventricular ejection fraction and left ventricular end-diastolic volume index did not differ in patients receiving the Björk-Shiley prosthesis from values in patients receiving the Hancock heterograft. Hence, the overall hemodynamic performance of both types of valves is remarkably similar. The choice between these two prostheses should, therefore, be governed not by the hemodynamic performance, but by other factors such as valve durability, risk of anticoagulation and incidence of valve-related complications.