Ann Thorac Surg 2008;86:691-692. doi:10.1016/j.athoracsur.2008.03.042
© 2008 The Society of Thoracic Surgeons
Correspondence
Reply
Michael A. Borger, MD, PhD
Leipzig Heart Center, Struempellstrasse 39, Leipzig 04289, Germany
(Email: michael.borger{at}med.uni-leipzig.de).
To the Editor:
We are pleased that Bottio and colleagues [1] took interest in our article comparing hemodynamic performance of the Perimount Magna (Edwards Lifesciences, Irvine, CA) and the Hancock II (Medtronic Inc, Minneapolis, MN) valves [2]. However, we do not agree with several of their criticisms. First, the authors state that the Hancock II valve does not have a supra-annular design, whereas the Perimount Magna does. Designation of an aortic valve as supra-annular, intra-annular or intra-supra-annular design is somewhat artificial and occasionally confusing. These designations are more appropriately applied to mechanical aortic valves because the metallic housing of the valve leaflets often protrude below the sewing ring of the valve [3]. The ultimate positioning of a tissue valve in a supra-annular or intra-anular position, however, depends more on the suturing technique that is used [4]. As long as the bioprosthesis has a scallop-shaped sewing ring, which both the Hancock II and Perimount Magna valves do, then the positioning will be intra-annular if an everting suture technique is used (ie, from aorta to ventricle with the pledgets on the aortic side of the annulus) or supra-annular if a non-everting technique is used (ie, from ventricle to aorta with the pledgets on the ventricular side of the annulus). In our study, a noneverting suture technique was used for all patients, and therefore both types of valves were inserted in a supra-annular position.
Second, Bottio and colleagues [1] criticized our use of the in vivo effective orifice area measurements. Although it is true that the EOA measurements are affected by flow, there are no reasons to suspect that the flow conditions would be different for the two groups of valve patients in our study. In addition, it is known that the EOA is the measure that correlates best with postoperative rest and exercise transvalvular gradients [5]. Furthermore, in vivo EOA measurements and gradients are the most commonly investigated and reported hemodynamic measures in clinical studies [4]. To suggest that in vivo measurements of the EOA are somehow inferior and should not be used when assessing valve performance means that we would have to discard of the majority of clinical valve research studies in the literature.
Bottio and colleagues [1] go on to state that hemodynamic measurements "should be taken at 1-year follow-up, because gradients may change during the first postoperative year." However, we have previously demonstrated that gradients continue to decrease in the first postoperative year only in patients who have received a stentless aortic valve [6]. Because both valves in the current study were stented bioprostheses, we believe that early postoperative measurements are valid. Furthermore, the matching process that we used ensured that we made a "size by size" comparison, as suggested by Kon [7].
Bottio and colleagues [1] also stated that we can not make any conclusions as to which valve has the better hemodynamic performance "by interpreting only one aspect of a complex scenario." We agree with this statement completely; therefore, we compared assessments of peak gradients, mean gradients, EOAs, and prevalence of patient-prosthesis mismatch between the two valves, and we found better performance for the Magna prosthesis on all counts. We also agree that the Hancock II and Magna valves are very different in design, and that the Hancock II valve is a second generation prosthesis. Therefore, we stated in our conclusions that "further studies should be performed comparing the Magna valve to newer generation, low profile porcine valves," such as the Mosaic Ultra (Medtronic Inc). However, the Mosaic Ultra was not clinically available at the time that our study was performed. Hopefully this study will be performed in the near future.
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References
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- Bottio T, Tarzia V, Rizzoli G, Gerosa G. Valve prostheses evaluation: it is a complex scenario and not only a matter of gradient Ann Thorac Surg 2008;86:691(letter).[Free Full Text]
- Borger MA, Nette AF, Maganti M, Feindel CM. Carpentier-Edwards Perimount Magna valve versus Medtronic Hancock II: a matched hemodynamic comparison Ann Thorac Surg 2007;83:2054-2059.[Abstract/Free Full Text]
- ISO guidelines 5840 Cardiovascular implants—cardiac valve prostheses4th ed. 2005.
- Sievers HH. Prosthetic aortic valve replacement J Thorac Cardiovasc Surg 2005;129:961-965.[Free Full Text]
- Pibarot P, Dumesnil JG. Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its management JACC 2000;36:1131-1141.[Abstract/Free Full Text]
- Borger MA, Carson SM, Ivanov J, et al. Stentless aortic valves are hemodynamically superior to stented valves during medium-term follow up: a large retrospective study Ann Thorac Surg 2005;80:2180-2185.[Abstract/Free Full Text]
- Kon N. Carpentier-Edwards Perimount Magna bioprosthesis: a stented valve with stentless performance? J Thorac Cardiovasc Surg 2005;130:1673-1674.
Related Article
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Valve Prostheses Evaluation: It Is a Complex Scenario and Not Only a Matter of Gradient
- Tomaso Bottio, Vincenzo Tarzia, Giulio Rizzoli, and Gino Gerosa
Ann. Thorac. Surg. 2008 86: 691.
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