title: Percutaneous aortic valve replacement: emerging tractability for sufficient intracardiac resection of the aortic valve.
abstract: OBJECTIVE
  : The feasibility of endovascular resection of highly calcified aortic valves has already been demonstrated by our group. Different endovascular and intracardiac tractability methods were applied. In this study, these technologies were analyzed comparing the tractability, the resection time, and the lesions in the surrounding tissue.
  
  
  METHODS
  : All aortic valve resections (seven human hearts and 21 porcine hearts) were performed using a Thulium:YAG laser (continuous wave, wavelength of 2.01 μm, 20 watts power rating). In the first resection system, the laser fiber was controlled by a free in-lying flexible endoscope (Ø 2.5 mm, length of 600 mm). The distal part of the endoscope (40 mm) was moved in one plane by proximal manual control (three degrees of freedom). The resection system was separated into defined rooms assigning one room for one tool. The fiber was controlled by the above-mentioned endoscope (*) (three degrees of freedom). The third resection system was a mechanical microactuator carrying the laser fiber (three degrees of freedom). The fourth resection system contains a rotatable inlay with defined rooms and a newly designed nitinol (NiTi) microactuator that controlled the laser fiber (four degrees of freedom). The resection time per leaflet was measured in minutes. Gross anatomy and histology in the surrounding tissue were evaluated.
  
  
  RESULTS
  : The resection time in approaches 1, 2, 3, and 4 was 5.5 ± 2.3 minutes, 7.4 ± 2.7 minutes, ± 6.6 minutes, and2.3 ± 1.2 minutes, respectively. The gross anatomy and histology of collateral damages revealed only superficial lesions of the surrounding tissue. The amount of lesions and the resection time were lower in the fourth approach with four degrees of freedom.
  
  
  CONCLUSIONS
  : This analysis demonstrated that a precise tractability with four degrees of freedom is necessary for a faster and safer endovascular resection of the aortic valve. The analysis will help to optimize the ongoing development of the endovascular and intracardiac resection technology.
authors.affiliation: From the *Department of Cardiovascular Surgery, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany; †Institute of Microtechnology, University of Braunschweig, Braunschweig, Germany; ‡Division of Cardiothoracic Surgery, University of Wisconsin, Madison, WI USA; §Institute for Biomedical Optics, University of Lübeck, Lübeck, Germany; ¶Division Microrobotics and Control Engineering, University of Oldenburg, Oldenburg, Germany; and ∥Institute of Anatomy, Christian-Albrechts-University of Kiel, Kiel, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Bombien
authors.forename: Claudia
authors.initials: C
authors.lastname: Lesche
authors.forename: Lucian
authors.initials: L
authors.lastname: Lozonschi
authors.forename: Max
authors.initials: M
authors.lastname: Feucker
authors.forename: Ralf
authors.initials: R
authors.lastname: Brinkmann
authors.forename: Christian
authors.initials: C
authors.lastname: Dahmen
authors.forename: Michael
authors.initials: M
authors.lastname: Schünke
authors.forename: Jochen
authors.initials: J
authors.lastname: Cremer
authors.forename: Georg
authors.initials: G
authors.lastname: Lutter