Differences in Performance of Five Types of Aortic Valve Prostheses: Haemodynamic Assessment by Dobutamine Stress Echocardiography

Study Questions:

What are the hemodynamic characteristics of five aortic valve prostheses?


A total of 106 patients undergoing aortic valve replacement with one of five prostheses (Elan stentless porcine xenograft [Aortech; Glasgow, UK], Pericarbon Freedom stentless bovine pericardial [Sorin Group; Gloucester, UK], Aspire stented porcine xenograft [Aortech], More stented bovine pericardial [Sorin Group], and Ultracor mechanical tilting-disk [Aortech]) were studied with preoperative echocardiography and 1-year postoperative dobutamine stress echocardiography (DSE). DSE also was performed among a total of 60 patients with a normal trileaflet aortic valve or variable degrees of aortic stenosis.


Stentless bioprostheses, whether porcine or bovine, displayed superior hemodynamics across nearly all echocardiographic parameters: lower gradients, larger effective orifice area, higher dimensionless severity index (DSI), and lower resistance, when compared with stented or mechanical prostheses. Comparing both stented designs, bovine tissue performed the worst at rest, but with stress, there was no difference. The stress performances of the stentless bioprostheses were similar to the native aortic valves with mild stenosis, whereas the performances of the stented and mechanical prostheses resembled that of native valves with mild-to-moderate stenosis. Hemodynamic differences, however, did not translate into differences in left ventricular mass reduction at 1 year.


Stentless bioprostheses displayed superior hemodynamics compared to stented tissue or mechanical prostheses, and had the closest performance to a normal, native aortic valve. Stress DSI data, least reliant on variable annulus/valve sizes and flow rates, provided the best hemodynamic discrimination.


Previous studies variably have shown hemodynamic superiority and hemodynamic equivalence of stentless compared to stented aortic bioprostheses––not necessarily surprising, because all stentless valves and all stented valves are not the same. Pertinent to this study, caution should be taken in extrapolating hemodynamic findings (or durability, or freedom from adverse events) between different heart valve prostheses, even if the basic material composition is similar (porcine, pericardial, etc.). The major message of this study should be taken only for these five heart valve prostheses, which are not major players in the US market. The conclusions should not be extrapolated to other devices, whether stented, stentless, or mechanical.

Clinical Topics: Cardiac Surgery, Noninvasive Imaging, Echocardiography/Ultrasound

Keywords: Heart Valve Prosthesis, Bioprosthesis, Heterografts, Hemodynamics, Echocardiography

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