Hemodynamic characterization of the Sorin Mitroflow pericardial bioprosthesis at rest and exercise

Background and aim of the study: Although the longterm clinical outcome after aortic valve replacement (AVR) with the Sorin Mitroflow pericardial bioprosthesis has been well described, few data are available with regards to hemodynamic performance. On the basis of its specialized design, with the pericardium mounted on the outside of the stent, the Mitroflow valve is considered to provide optimal opening and orifice areas. Methods: Between February 2006 and April 2007, a total of 127 patients (66 females, 61 males; mean age 77.6 ± 5.2 years) underwent AVR with the Mitroflow valve at the authors' institution. Echocardiography was performed at discharge in 91 patients, while a six-month follow up examination was conducted in 78 (including ergometer hemodynamics in 25 cases). Results: The mean systolic pressure gradient (MPG) ranged from 19.7 ± 3.3 mmHg (size 19 valve) to 12.4 ± 2.4 mmHg (size 27 valve), and the mean effective orifice area (EOA) from 0.96 ± 0.0 cm² (size 19 valve) to 2.36 ± 0.4 cm² (size 27 valve). The incidence of mildto-moderate and severe prosthesis-patient mismatch (PPM) was 33% and 10% at the six-month follow up. During exercise (25 W-100 W), the MPG increased from 17.1 ± 3.6 mmHg to 23.6 mmHg in valve sizes 19 to 21, and from 12.2 ± 3.6 mmHg to 15.9 ± 2.5 mmHg in valve sizes 23 to 27. The effective orifice fraction (EOF = EOA/annulus area) was 38 ± 7%. Conclusion: The Mitroflow valve exhibits an adequate MPG and EOA, as might be expected for a pericardial bioprosthesis. Of note, the gradient increase during exercise was low, especially for the larger valve sizes. Due to its special design, the Mitroflow prosthesis shows a large opening, as demonstrated by the high EOF. These data relating to the EOA of all prosthesis sizes may help surgeons to select the minimum prosthesis size in order to prevent PPM.