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Eur J Cardiothorac Surg 2007;32:295. doi:10.1016/j.ejcts.2007.05.016
Copyright © 2007, European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved
Department of Cardiovascular Surgery, School of Medicine, University of Kiel, Arnold Heller Str. 7, D-24105 Kiel, Kiel, Germany
Received 24 May 2007; received in revised form 24 May 2007; accepted 24 May 2007.
* Corresponding author. Tel.: +49 431 597 4582; fax: +49 431 597 4542. (Email: lutter{at}kielheart.uni-kiel.de).
First, we would like to congratulate Flecher et al. [1] for their work—an important contribution to basic research on percutaneous aortic valve technologies. Unfortunately, interest on basic research in this field seems to have decreased since the human clinical trials began. But despite the clinical accomplishment of percutaneous valve technologies in the last 5 years, many problems are yet unsolved [2].
Unsuccessful aortic valved stent implantations have been reported in different experimental and clinical articles [2]. These implantations are accompanied by additional problems, as follows: mild to severe paravalvular leakages, occlusion of coronary ostia, embolization of debris, migration of the valved stent, mild increase of the mitral insufficiency, and remaining small effective aortic valve area leading to intraprocedural death. These problems are caused by technical difficulties due to the delivery system and the actual stent design. There are no experimental studies about various stent designs and their performance in the non-resected annulus [2].
In the present article, the Duran group analyzes coronary flow reduction after correct aortic valved stent implantation. These in vitro data show a significant decrease of coronary perfusion in a porcine model (flow reduction: LCA: 43%; RCA: 18%).
In contrast, after resection of the native valve and subsequent valve stent implantation, the coronary flow measurement demonstrated only a negligible decrease.
This is very important information. The data shows that a previous removal of the native valve prevents a decrease of coronary flow. Besides larger effective aortic valve area, reduction of paravalvular leakages, etc., this study is another argument for the necessity of endovascular resection. This requires a change in current opinion concerning percutaneous aortic valve resection [2–4].
As we have demonstrated earlier, the endovascular resection of diseased aortic valves can be performed with a Thulium:YAG laser or a high-pressure water stream scalpel in vitro and in situ [3,4]. To prevent central and peripheral embolization caused by the calcific debris, our group uses an aortic valve isolation chamber [3,4].
Overall, percutaneous resection is difficult to perform. A significant research basis is necessary to the end of achieving clinical beating heart resection. Unpublished data of our group demonstrate that the removal of the native valve is necessary for good alignment of the valved stent with respect to the annulus and ascending aorta. Additionally, new three-dimensional stents must be developed, which will better fit into the aortic annulus and the ascending aorta [2]. The rapid prototyping of valved stents for the pulmonary position is an interesting option [5], which we fully support.
In conclusion, the present study of Flecher et al. [1] demonstrates that percutaneous valve technology requires significant benchmark research. We have to convince the sceptical physicians with solid scientific data.
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  R. Quaden, T. Attmann, M. Schunke, D. Theisen-Kunde, J. Cremer, and G. Lutter Percutaneous aortic valve replacement: Endovascular resection of human aortic valves in situ. J. Thorac. Cardiovasc. Surg., May 1, 2008; 135(5): 1081 - 1086. [Abstract] [Full Text] [PDF]
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