**3.7.3 Guidance during Trans-Aortic Valve Implantation (TAVI)**

Trans-Aortic Valve Implantation requires exact positioning of the valve in the aortic root to prevent complications. A good fluoroscopic view is essential, whereby an exact perpendicular angle to the aortic root is considered to be optimal for the implantation. Recently, applications have been released which support the surgeon in selecting this optimal fluoroscopy angulation or even drive the C-arm automatically into the perpendicular view to the aortic root (see Fig. 9).

Some approaches are based on pre-operative CT images, which are used to segment the aorta and calculate optimal viewing angles for valve implantations. CT images must be registered with DynaCT or fluoroscopic images to transfer the 3D volume to the actual angiographic system. Errors during the registration process might result in diversification from the optimal angulations of the C-arm and must be manually corrected. Additionally, anatomical variations between the acquisition of the pre-operatively CT image and surgery are not accounted for. Patients are generally imaged with hands-up in a CT scanner while surgery is performed with arms aside the patient, which leads to substantial errors.

Algorithms purely based on DynaCT images acquired in the OR by the angiographic system are inherently registered to the patient and show the present anatomy structures. With such an approach, the surgeon does not rely on pre-operative CT images acquired by the radiological department which simplifies the workflow in the OR and reduces errors in the process.

Fig. 8. Overlay of 3D DynaCT image (orange) on top of a fluoroscopic image during cardiac resynchronization therapy. Courtesy of K.-J. Gutleben, M.D., G. Nölker, M.D. A. Sinha, M.D., J. Brachmann, M.D., Department of Cardiology, Klinikum Coburg, Germany.

surgeon. For example to place fenestrated stents, a pre-operatively acquired CT image could be used to mark the ostia of the visceral arteries manually by the surgeon. By aligning the pre-operative CT image with the intra-operatively acquired DynaCT image, the ostia can be displayed (beside the contour of the arteries) in the fluoroscopic image. Notably, this truly is 3D information, i.e. any change in the C-arm position or angulations will update the view on

Trans-Aortic Valve Implantation requires exact positioning of the valve in the aortic root to prevent complications. A good fluoroscopic view is essential, whereby an exact perpendicular angle to the aortic root is considered to be optimal for the implantation. Recently, applications have been released which support the surgeon in selecting this optimal fluoroscopy angulation or even drive the C-arm automatically into the

Some approaches are based on pre-operative CT images, which are used to segment the aorta and calculate optimal viewing angles for valve implantations. CT images must be registered with DynaCT or fluoroscopic images to transfer the 3D volume to the actual angiographic system. Errors during the registration process might result in diversification from the optimal angulations of the C-arm and must be manually corrected. Additionally, anatomical variations between the acquisition of the pre-operatively CT image and surgery are not accounted for. Patients are generally imaged with hands-up in a CT scanner while

Algorithms purely based on DynaCT images acquired in the OR by the angiographic system are inherently registered to the patient and show the present anatomy structures. With such an approach, the surgeon does not rely on pre-operative CT images acquired by the radiological department which simplifies the workflow in the OR and reduces errors in the

surgery is performed with arms aside the patient, which leads to substantial errors.

the marks to perfectly match the live fluoroscopy image.

perpendicular view to the aortic root (see Fig. 9).

process.

**3.7.3 Guidance during Trans-Aortic Valve Implantation (TAVI)** 

Fig. 9. Image-driven guidance during Trans-Aortic Valve Implantation (TAVI). Contours were automatically segmented from a 3D DynaCT image and the C-arm was positioned perpendicular to the aortic root for live fluroscopy based on anatomical landmarks extracted from the DynaCT image without user interaction. (Siemens AG, Forchheim, Germany)
