Abstract 1563 Optimal viewing angles of mechanical aortic valves in cinefluoroscopy and computed tomography

Clin Res Cardiol (2023). https://doi.org/10.1007/s00392-023-02180-w
Optimal viewing angles of mechanical aortic valves in cinefluoroscopy and computed tomography
M. M. Marquardt¹, A. A. Derda¹, A. Martens², E. Mirena¹, J. Vogel-Claussen³, T. Kempf¹, A. Haverich², J. Bauersachs¹, L. C. Napp¹
¹Kardiologie und Angiologie, Medizinische Hochschule Hannover, Hannover; ²Klinik für Herz-, Thorax-, Transplantations- und Gefäßchirurgie, OE 6217, Medizinische Hochschule Hannover, Hannover; ³3 Institut für Diagnostische und Interventionelle Radiologie, Medizinische Hochschule Hannover, Hannover;
Introduction Cinefluoroscopy is a simple and effective method for determining opening angles of mechanical heart valves (MHV), and recommended by current guidelines in patients with suspected MHV dysfunction. In a previous study, we found that MHV visualization by cinefluoroscopy is frequently insufficient, likely due to educational limitations and suboptimal viewing angles. This study aimed to investigate anatomy after surgical aortic valve replacement with MHV by analyzing computed tomography (CT) studies after surgery, in order to inform future cinefluoroscopy examinations. Methods and Results 9566 CT scans were retrospectively screened. 254 scans from 244 individual patients were selected (median 5 years after MHV surgery) and further investigated according to prespecified criteria for optimal MHV visualization. 86.6% were CT scans after the first MHV surgery, and 100.0% of patients had bi-leaflet MHV in aortic position. Analysis focused on a ring view for determining leaflet position (i.e. rotational position) and an orthogonal view for determining opening of the leaflets. The ring view showed an apparent clustering of angles in RAO (40°-60°) – CRAN (60°-100°) and in LAO (40°-60°) –CAUD (60°-100°) angulations. In contrast, the angles in the orthogonal view showed no clustering, but an S-shape pattern from RAO CAUD towards LAO CRAN, suggesting that rotational position of the valve in the native annulus determines viewing angles. Rotation was analyzed by measuring the angle α between MHV leaflets and the left main coronary artery ostium as a landmark. α varied between 0 and 180° and had a normal distribution between patients. After correcting for rotational position by dividing angles in the orthogonal view into quartiles depending on α, a clear clustering was apparent: For α angles of 0°-44.9°, the optimal viewing angle was between RAO (0°-60°) and CAUD (0°-40°), for α of 45°-89.9° between LAO (0°-60°) and CAUD/CRAN (0°-20/0°-30°), for α of 90°-134.9° between LAO (30°-90°) and CRAN (10°-50°), and for α of 135°-180° between LAO (70°-120°) and CRAN (30°-50°). Conclusion Ring views of MHV in aortic position cluster in RAO CRAN and LAO CAUD angulations. As no standard exists for rotational position of MHV during surgery, rotation strongly varied between patients even with identical MHV types, precluding angle prediction for orthogonal views. This study provides essential knowledge for understanding anatomy after MHV surgery. Analysis of available CT scans prior to cinefluoroscopy appears mandatory, in order to perform time- and X-ray-saving examinations with optimal MHV visualization.
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