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

Abstract

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.

Assessment of normal and abnormal prosthetic mitral valves by Doppler echocardiography

“…The reliability of transprosthetic gradient calculation using the modified Bernouilli equation has been previously validated by simultaneous Doppler-hemodynamic studies [15][16][17]. Our results for each type of valve are in agreement with other Doppler studies [7,8,18] and with prior invasive data [19][20][21]. Most of the mitral prosthetic valves exhibit a low mean gradient ranging from 2 to 6 mm Hg, with the lowest values obtained in Carpentier, St. Jude, and Liotta prostheses.…”

“…Second, the number of patients studied for each size is relatively tow and a very large number of prostheses of different sizes would need to be studied to obtain clear differences in flow velocities across prostheses of different sizes [5]. Finally, most of the published studies report a wide range of mean gradients for each type and each size of prostheses and a considerable overlap between valves of different size, as previously reported by invasive studies [19][20][21]. Thus, determination of a 'normal' gradient for each valve seems difficult and of limited clinical value.…”

“…Third, hemodynamic studies have shown that effective area of a prosthetic valve could vary with volume flow, both in tissue [19] and mechanical valves [20].…”

Tissue Valve Is the Preferred Option for Patients Aged 60 and Older

“…The only direct comparison of mechanical versus bioprostheses in RCT showed no significant difference in valve areas between Bjork-Shiley valves and porcine valve after 6 months of implantation. 50 In vivo measurement data show similar valve area index between the newer generation mechanical valves (23)(24) 52 although no study has compared the 2 under same circumstance. Therefore, a belief that mechanical valve has better hemodynamics is a myth.…”

Valve Prosthesis–Patient Mismatch (VP–PM)

“…4) (42). Two more recent echocardiographic/Doppler studies from the Mayo Clinic of patients studied within 1 week of mitral porcine mitral bioprosthesis (43) (Fig.…”