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Cutting precision in a novel aortic valve resection tool. Research in progress^,

^a Department of Thoracic and Cardiovascular Surgery, West-German Heart Center Essen, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
^b Endosmart GmbH, Stutensee, Germany
^c Department of Physical Engineering, Fachhochschule Gelsenkirchen, Gelsenkirchen, Germany

*Corresponding author. Tel.: +49-201-723-84912; fax: +49-201-723-5451.

E-mail address: daniel.wendt{at}uk-essen.de (D. Wendt).

Background: We recently demonstrated the first in-vitro cutting results of a minimal-invasive aortic valve resection tool. The current study was designed to assess the cutting accuracy of this new device improved by the implementation of a linear motor-based propulsion unit. Methods: Native aortic valves of isolated swine hearts (valve diameter 17.8±0.9 mm, mean±S.D.) were artificially stenosed and calcified (n=7). Subsequently, valves were resected by the use of a new aortic valve resection tool. The cutting process was performed by fitting the instrument with foldable Nitinol cutting blades (diameter 15 mm) and two software-operated linear motors combined with separated manual rotation. Aortic valve area was measured pre- and postprocedure by software-guided binary area calculation. Aortic valve residue has been determined and the grade of accuracy has been assessed via calculating the average midpoint of the neoannulus. Furthermore, radial deviation of concentricity was calculated and cutting time was measured. Results: Aortic valve resection was successful in all cases and nearly all leaflets (2.5±0.4) with a weight of 0.22±0.12 g were cut. Aortic valve area increased significantly (0.3±0.1 cm² vs. 1.1±0.2 cm², P<0.001) with a mean cutting time of 49.7±15.0 s. Mean lateral leaflet rim within the annulus was 3.2±3.2 mm. Cutting precision revealed a median deviation of the cutting ring from the desired position of 1.3±0.6 mm (y-axis) and 1.4±0.5 mm (x-axis). Median center deviation of the cutting ring was 2.6±0.8 mm. Conclusions: The present study clearly confirmed ability of an accelerated cutting of stenotic aortic valve by the aortic valve resection tool. Nearly all leaflets were cut and a small rim was left within the annulus, hence providing an ideal ‘landing zone' for the new prosthesis. Nevertheless, the aortic valve resection tool should be enhanced by adding a centering mechanism, thus achieving a more precise cutting process in order to avoid secondary damage.

Key Words: Aortic stenosis; Aortic valve resection; Resection tool; Sutureless valve implantation; Cutting performance; Minimal-invasive