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OBJECTIVE: Transcatheter aortic valve implantation (TAVI) has become a widely used option for patients suffering of aortic stenosis. For transcatheter resection of calcified aortic valves prior to TAVI, five different prototypes enabeling mechanical resection have been developed and tested in vitro.
METHODS: The handling qualities and cutting capabilities of five experimental transcatheter-resection-devices were assessed in vitro. General feasibility, positioning, and injuries arising from resection were examined in ten porcine aortic valves. Furthermore, punch experiments (n=5 / device) were conducted in human aortic valves (reconstructed from several calcified human aortic semilunar cusps) and the resected areas were determined according to their size following a standardized protocol. In adition, the particles outside the resection chamber were recorded.
RESULTS: Two of five resection devices showed inapropriate handling during the positioning procedure and inadequate resection properties and which were therefore calssified as non adequate. The remaining three devices showed adequate handling and resection properties throughout the experimental resection of the porcine valves.
In the punch experiments of human calcified valves, these prototypes showed mean resection times of 9 ± 1.2 s, 44 +/- 13.56 and 51.5 ± 18.9 s with a respectively resected area of 62 %, 7 % and 22 %. The best positioning in terms of handling feasability was performed by the second prototype in comparison with the other prototypes. Overall, a negative correlation with the total resected surface area was observed relative to the degree of calcification in the aortic valves.
Further findings were associated with injuries of the surrounding tissue, particles outside of the resection chamber and damages recorded at the resection insturments.
CONCLUSIONS: Five transcatheter devices were designed, based on different mechanical cutting techniques. Three of these five prototypes proved to be promising with regard to handling feasibility and cutting properties during this initial experimental study. However, the prototype with the best resection results showed marked deficiencies with regard to the risk of injury to the immediate surrounding surgical area. The advantages of individual punches thus need to be combined in order to optimize the existing resection instruments. The results of this study result in an optimized resection instrument.