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COMPUTED TOMOGRAPHIC COMPARISON OF DIFFERENT PROTOTYPE DESIGNS FOR OFF-PUMP MITRAL VALVED STENT IMPLANTATION
Saskia Pokorny1, Holger Hettich1, Alin Heinig1, Telse Bähr1, Benjamin Sattler1, Michael M. Morlock2, Jochen Cremer1, Georg Lutter1.
1University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany, 2Hamburg University of Technology, Hamburg, Germany.
OBJECTIVE: Implantation of a mitral valved stent using an off-pump technique is a novel approach for treatment of mitral regurgitation. This study compares the in vivo performance of two different prototypes using cardiac CT.
METHODS: Eight pigs received a self-expanding mitral valved stent, consisting of an atrial element connected to a ventricular body accommodating a bioprosthetic heart valve at a preset angle. The angle in between atrial element and ventricular body was modified from 45° in the first design (n=4) to 90° in the second design (n=4).
Cardiac CT was performed 10 days (45° n=4; 90° n=2) and one month after implantation (90° n=2). Focus of this study was the evaluation of stent design related parameters such as the obstruction of the LVOT and the shaping of the valved stent (oval deformation, angular deflection). To evaluate the angular deflection, the annulus was divided into four zones.
RESULTS: All animals were successfully implanted and were in good health at the time of CT examination. Correct position of the stents within the mitral annulus and full expansion of the ventricular element were observed in all cases.
Minor deformation of 1.6±1.3 mm of the ventricular body (45° n=3, 90° n=2) were detected in five of eight cases. At the atrioventricular junction, large deformations of the stent structure were observed in all cases. The 45° stents revealed a greater deflection of the preset stent geometry, even though the overall angle was larger in the group of 90° stents (Table1). No obstruction of the LVOT through the stent body was observed in five of eight animals. An obstruction of 20±8 % was found in the remaining three animals (45° n=2 ; 90° n=1).
CONCLUSIONS: Good in vivo performance of the novel mitral valved stents was demonstrated and critical areas within the stent design were identified.
The results indicate that larger preset angles lead to less stent deflection and hence could reduce the mechanical loading and the risk of stent fractures.
| Prototype | septal | anterolateral | posterolateral | posteromedial |
| 90° (n=4) | 21.9° ± 3.8° | 13.4° ± 8.9° | 22.4° ± 6.5° | 18.8° ± 4.7° |
| 45° (n=4) | 56.4° ± 14.5° | 41.4° ± 19.4° | 38.8° ± 13.5° | 32° ± 12° |
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