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Session: Cardiovascular diseases
Session starts: Friday 25 January, 13:00
Presentation starts: 13:15
Room: Lecture room 558

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Esther Maas (Eindhoven University of Technology)
Richard Lopata (Eindhoven University of Technology)
Frans van de Vosse (Eindhoven University of Technology)
Arthur Bouwman (Catharina Ziekenhuis Eindhoven)
Patrick Houthuizen (Catharina Ziekenhuis Eindhoven)
Peter Bovendeerd (Eindhoven University of Technology)

Abstract:
The diagnosis and timing of treatment in aortic valve stenosis patients are currently predominantly based on aortic valve parameters. It is however known that aortic valve stenosis increases left ventricular pressure, which may reduce subendocardial perfusion and can lead to subendocardial dysfunction and subendocardial infarction. Subendocardial ischemia is expected to affect apex-to-base rotation of the left ventricle, since this rotation represents mechanical equilibrium between the subepicardial fibers and the subendocardial fibers. More specifically, rotation is expected to increase with increasing endocardial ischemia. In this study, rotation is investigated using speckle tracking on short-axis B-mode images of the heart. First, we investigated the accuracy of rotations obtained by performing speckle tracking, using a mathematical model of left ventricular kinematics. This is done by performing speckle tracking on simulated B-mode images created using the Field II software. The maximal rotation determined with speckle tracking was 30% lower than the rotation prescribed in the model. Tracking seemed most hindered in regions rotating lateral to the transducer, most likely caused by the low precision of lateral displacement estimates. Secondly, we analysed B-mode images of aortic stenosis patients before (pre, n=5) and immediately after (post, n=3) a TAVI procedure and healthy volunteers (n=4). The apex-to-base rotation during the ejection phase is plotted against the circumferential strain, to correct for the decreased overall contractility. The negative slope of this plot is the parameter RRTC, the relative-rotation-to-contraction. The average RRTC is 50 degrees for the pre group, 42 degrees for the post group and 29 degrees for the healthy volunteers. While these results support our hypothesis, no statistically significant conclusions can be drawn because of the small numbers and errors in the speckle tracking. However, this method seems promising to determine subendocardial ischemia in aortic valve stenosis patients, which can in the future be used to improve the timing of aortic valve replacement.