Where is the common sense in aortic valve replacement? A review of hemodynamics and sizing of stented tissue valves

Abstract

Heated debates revolve around the hemodynamic performance of stented aortic tissue valves. Because the opening area strongly influences the generation of a pressure gradient over the prosthesis, and the outer diameter determines which valve actually fits into the aortic root, it would seem logical that the valve with the greatest opening area in relation to its outer diameter should allow the best hemodynamic performance. Interestingly, neither of these 2 parameters is reflected by the manufacturing companies' size labels or suggested sizing strategies. In addition, it is known that valves with the same size label from different companies may differ significantly in their actual dimension (outer diameter). Finally, the manufacturer-suggested sizing strategies differ so much that expected differences from valve design may get lost because of differences in sizing. These size and sizing differences and the lack of information on the geometric opening area complicate true hemodynamic comparisons significantly. Furthermore, some fluid dynamic considerations regarding the determination of opening area by echocardiography (the effective orifice area) introduce additional obscuring factors in the attempt to compare hemodynamic performance data of different stented tissue valves. We analyzed the true dimensions of different tissue prostheses and the manufacturer-suggested sizing strategies in relation to published effective orifice areas. We have demonstrated how sizing and implantation strategy have much greater impact on postoperative valve hemodynamics than valve brand or type. In addition, our findings may explain the different opinions regarding valve hemodynamics of different tissue valves.

Early haemodynamic performance of a latest generation supra-annular aortic bioprosthesis: experience from a large single-centre series

“…The cylindrical end determines the appropriate size of the annulus. The corresponding valve replica end is used to visualize supra-annular placement for optimal sizing, thus helping the surgeon to implant the biggest size possible [as is the case with the newer generation tissue valves, such as the Epic Supra, the Perimount Magna Ease (Edwards Lifesciences), the Mosaic Ultra (Medtronic)] [12]. All described features and promising in vitro data were suggestive of eventually reaching a good haemodynamic performance in vivo.…”

“…Owing to a lack of uniformity in tissue valve sizes, proper haemodynamic comparison of different tissue valves may be difficult and even misleading. Therefore, non-randomized unmatched comparisons of the haemodynamic performance of different bioprostheses should be interpreted with caution [12]. In an annulus-size-matched ) PPM was present, respectively.…”

Does the type of suture technique affect the fluid-dynamic performance of bioprostheses implanted in small aortic roots? Results from an in vitro study

“…However, fluidodynamic characteristics tend to change when the bioprosthesis is surgically implanted. Indeed, the in vivo scenario is very complex and, in this context, the performance of the prosthesis may be influenced by many factors, not least sizing strategy (2). Consequently, implanting a prosthesis that meets the patient's cardiac output requirement needs experience and knowledge of the true dimensions of the bioprosthesis -its internal and external diameters -and of tissue annulus diameters.…”

“…The in vivo hemodynamic performance of a bioprosthesis imBplanted in aortic position is affected by the characteristics of the prosthesis, such as stent design, type and position of the leaflets, sewing-ring size and the sizing strategy adopted (1,2).…”

Bernoulli in the Operating Room: From the Perspective of a Cardiac Surgeon

“…14 A minimal prosthesis gradient is achieved through complete resection of the calcified aortic leaflets and supra-annular implantation of a large prosthesis with a maximum valve opening. 16 Of course, the gradient over the implanted valve depends not only on the surgical technique but also on the type of implanted prosthesis. 17 In addition to those described above, the Bernoulli law explains many other phenomena both inside and outside medicine.…”