The Freedom SOLO bovine pericardial stentless valve

Research Reports in Clinical Cardiology Dovepress open access to scientific and medical research Review Research Reports in Clinical Cardiology downloaded from https://www.dovepress.com/ by 51.38.247.138 on 12-Jul-2018 For personal use only. Open Access Full Text Article The Freedom SOLO bovine pericardial stentless valve This article was published in the following Dove Press journal: Research Reports in Clinical Cardiology 2 December 2014 Number of times this article has been viewed Olaf Stanger Hendrik Tevaearai Thierry Carrel Clinic for Cardiovascular Surgery, University Hospital Berne, Switzerland Background Correspondence: Thierry Carrel Clinic for Cardiovascular Surgery, University Hospital, CH-3010 Berne, Switzerland Tel +41 31 632 23 75 Fax +41 31 632 44 43 Email Aortic valve prostheses have evolved considerably over the last 50 years, especially with respect to technical aspects, such as design, implantation technique, and processing. Treatment of aortic valve pathologies with valve prostheses began with the use of cage-ball valves in the descending aorta of patients with aortic regurgitation.1 This was followed by subcoronary aortic valve replacement (AVR) using aortic allografts (homografts),2,3 and mechanical cage-ball and “monostrut” models in the 1960s.4 Interestingly, homografts mounted on a stented frame were used as early as in 1965, to simplify implantation techniques; however, these stents caused tissue failure within a few years and as such, were less durable than freehand-sewn homografts and were subsequently abandoned.5 Stent-mounted porcine xenograft valves, first implanted in 1964 and 1965,6,7 were treated with mercurial solution and formaldehyde8 in order to arrest autolysis and fix tissue, but this treatment also caused shrinkage and stiffness. The introduction 349 submit your manuscript | www.dovepress.com Research Reports in Clinical Cardiology 2014:5 349–361 Dovepress © 2014 Stanger et al. This work is published by Dove Medical Press Limited, and licensed under Creative Commons Attribution – Non Commercial (unported, v3.0) License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php http://dx.doi.org/10.2147/RRCC.S72978 Powered by TCPDF (www.tcpdf.org) Abstract: The third-generation bovine pericardium Freedom SOLO (FS) stentless valve emerged in 2004 as a modified version of the Pericarbon Freedom stentless valve and as a very attractive alternative to stented bioprostheses. The design, choice of tissue, and anticalcification treatment fulfill most, if not all, requirements for an ideal valve substitute. The FS combines the singlesuture, subcoronary implantation technique with the latest-generation bovine pericardial tissue and novel anticalcification treatment. The design allows imitation of the native healthy valve through unrestricted adaption to the patient’s anatomy, reproducing a normal valve/root complex. However, despite hemodynamic performance superior to stented valves, we are approaching a critical observation period as superior durability, freedom from structural valve deterioration, and nonstructural failure has not been proven as expected. However, optimal performance and freedom from structural valve deterioration depend on correct sizing and perfect symmetric implantation, to ensure low leaflet stress. Any malpositioning can lead to tissue fatigue over time. Furthermore, the potential for better outcomes depends on optimal patient selection and observance of the limitations for the use of stentless valves, particularly for the FS. Clearly, stentless valve implantation techniques are less reproducible and standardized, and require surgeondependent experience and skill. Regardless of whether or not stentless valve durability surpasses third-generation stented bioprostheses, they will continue to play a role in the surgical repertoire. This review intends to help practitioners avoid pitfalls, observe limitations, and improve patient selection for optimal long-term outcome with the attractive FS stentless valve. Keywords: aortic valve, bioprosthesis, cardiac surgery, aortic valve replacement, tissue valve, stentless aortic valve, hemodynamics, long-term results Research Reports in Clinical Cardiology downloaded from https://www.dovepress.com/ by 51.38.247.138 on 12-Jul-2018 For personal use only. Stanger et al of glutaraldehyde (GA) fixation9 represents the next major advance and is still used today for all bioprostheses. However, the high rate of early mechanical failure with first-generation stented porcine xenografts10 soon became obvious, particularly in younger patients and thus stimulated work to improve preservation, biocompatibility, design, and valve mounting strategies.11 Conceptually, the ideal valve substitute has remained largely unchanged12 and includes unobstructed central flow, maximum effective orifice area (EOA) with low transvalvular gradients, low thrombogenicity, prolonged durability, easy implantability, resistance to infection, and freedom from anticoagulation.13 However, still today, no single prosthesis fulfils all of these criteria. Widespread use of homografts is limited by the practical problems of restricted availability of different sized specimens, demanding techniques, and questionable long-term outcomes, while mechanical valves still require lifelong anticoagulation with the potential of undesirable secondary events. Following the observation of significantly lower valve leaflet deterioration in homografts compared with (first-generation) stented xenografts,14 the stentless valve concept was proposed to combine the advantages of both homografts (nonobstructive EOA) and stented bioprostheses (unlimited availability). Furthermore, a flexible aortic root was believed to be essential for natural leaflet stress distribution; thus, implantation of an unstented xenograft with minimal disruption of aortic root dynamics was expected to reduce dynamic stress on leaflets, thereby translating into a lower probability of structural valve deterioration (SVD).15 In addition, the importance of left ventricular (LV) mass was identified in the Framingham Heart Study,16 and complete regression of LV hypertrophy (LVH) was defined as a major prognostic factor determining late outcome after AVR.17 Importantly, the stentless design was expected to better permit regression as a result of superior hemodynamics due to lower gradients in the absence of obstructive stents. The current review describes the Freedom SOLO (FS) stentless valve (Sorin Biomedica, Saluggia, Italy), a valve that was introduced in our teaching institu (...truncated)