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Overview of Mixed and Augmented Reality in Medicine
Published in Terry M. Peters, Cristian A. Linte, Ziv Yaniv, Jacqueline Williams, Mixed and Augmented Reality in Medicine, 2018
Minimally invasive valvular intervention commonly requires intraprocedural navigation to provide spatial and temporal information of relevant cardiac structures and device components. Recently, intraprocedural transesophageal echocardiography (TEE) has been exploited for this purpose due to its accessibility, low cost, ease of use, and real-time imaging capability. However, the position and orientation of tissue targets relative to surgical tools can be challenging to perceive, particularly when using 2D imaging planes. Li et al. (2015) proposed the use of CT images to generate a high-quality 3D context to enhance US images using image registration and provide an augmented guidance system with minimal impact on standard clinical workflow. They also described the generation of synthetic 4D CT images via deformable registration to the TEE US image to avoid the excessive radiation required for dynamic CT. Their results show that synthetically generated dynamic CT images are a suitable surrogate for real, dynamic CT images with respect to providing context for the US image. Chapter 16 of this book elaborates on these approaches in more depth.
Sensor-Enabled 3D Printed Tissue-Mimicking Phantoms: Application in Pre-Procedural Planning for Transcatheter Aortic Valve Replacement
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Kan Wang, Chuck Zhang, Ben Wang, Mani A Vannan, Zhen Qian
In 2017, Qian et al. reported a study that aimed to develop a procedure simulation platform for TAVR using 3D printed patient-specific aortic valve phantoms [55]. It was a retrospective, single-center, observational study approved by the Institutional Review Board of Piedmont Healthcare. This study included 18 patients who underwent clinically indicated TAVR with a CoreValve system (self-expanding valve) (Medtronic, Minneapolis, Minnesota) between April 2014 and September 2015. The patients were selected using stratified random sampling, in which seven to eight patients were randomly selected in the none, trace-to-mild, and moderate-to-severe groups that constituted a representative spectrum of different degrees of post-TAVR PVL. Before the TAVR procedure, all patients received a contrast-enhanced cardiac CT scan. Prosthesis size was determined by the CT-derived annular diameter as per standard recommendation [62]. During the TAVR procedure, valve implantation was performed under the guidance of fluoroscopy and transesophageal echocardiography (TEE). Even though the initial positioning and anchoring of the self-expanding valve system was optimal and successful in all 18 patients, TEE revealed that seven patients had moderate-to-severe PVL after the initial valve deployment, which required post-deployment balloon dilation in an attempt to reduce PVL. TEE post-balloon dilation showed the PVL in three of these patients was reduced to trace or mild, and in the other four, the PVL degrees remained unchanged.
Aortic Valve Mechanics
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
J. Dallard, M. Boodhwani, M. R. Labrosse
As can be seen from Table 9.1, various approaches have been used in the literature to carry out measurements in AVs, from transesophageal echocardiography in healthy volunteers (Bierbach et al., 2010) and patients (de Kerchove et al., 2015) to intraoperative measurements (Schäfers et al., 2013), in vitro measurements (Kunzelman et al., 1994), and measurements using silicone rubber molds (Labrosse et al., 2006). Overall, in healthy subjects, VAJ diameters in the range of 21–24 mm, STJ diameters in the range of 19–25 mm, and sinus heights in the range of 21–23 mm have been observed. As expected, AVs in children (age = 5.8 ± 3 years) presented with lower dimensions, with 14, 15, and 14 mm, respectively, for the VAJ diameter, the STJ diameter, and the sinus height (Bierbach et al., 2010). Patients affected by aortic root dilatation exhibited a range of 24–30 mm for the VAJ diameter and 32–41 mm for the STJ diameter (Schäfers et al., 2013; de Kerchove et al., 2015).
Appropriate use criteria of left atrial appendage closure devices: latest evidences
Published in Expert Review of Medical Devices, 2023
Fabrizio Guarracini, Eleonora Bonvicini, Alberto Preda, Marta Martin, Simone Muraglia, Giulia Casagranda, Marianna Mochen, Alessio Coser, Silvia Quintarelli, Stefano Branzoli, Roberto Bonmassari, Massimiliano Marini, Patrizio Mazzone
Transthoracic echocardiography (TTE) is an imaging modality used in most patients, but it has only limited ability to study the LAA, despite an enhanced visualization is possible with ultrasound contrast [46]. TTE can be used a screening exam to evaluated absolute contraindication to the procedure, like mitral stenosis or ventricular thrombus. Transesophageal echocardiography (TEE) instead is the gold standard for LAA evaluation [47]. LAA morphology, contraction, flow velocity, and the presence of slude or thrombi should be assessed, beside near structure evaluation, like mitral valve, left atrium, and left ventriculus. The use of contrast may improve suboptimal images, while the application of 3D methodologies has improved the visualization of the LAA in its entirety with more accuracy [48].
Safety and effectiveness of left atrial appendage closure in patients with non-valvular atrial fibrillation and prior major bleeding
Published in Expert Review of Medical Devices, 2021
Mingzhong Zhao, Cody R. Hou, Xiaolin Xiong, Felix Post, Nora Herold, Jiangtao Yu
The implantation procedure was performed in all subjects. The LAAC procedure was similar to that reported in previous literature [13]. Briefly, this procedure was performed under general anesthesia with the guidance of fluoroscopy and transesophageal echocardiography (TEE). Intravenous heparin was administered at a dose of 70–100 IU/kg to maintain an activated clotting time of 250–300 seconds after successfully puncturing the interatrial septum. All device implantation met PASS criteria (position, anchor, size, and seal) before release of the device. The successful implantation of the device was defined as complete occlusion of left atrial appendage or closure with less than 5 mm peri-device flow. Patients stayed in the hospital overnight and were discharged within 1 or 2 days post-procedure if no severe pericardial effusion, cardiac tamponade, significant procedure-associated bleeding, or other procedure complications were found.
Devices for transcatheter mitral valve repair: current technology and a glimpse into the future
Published in Expert Review of Medical Devices, 2021
Daniel Perez-Camargo, Mi Chen, Maurizio Taramasso
The device consists of the implant and the delivery system. The ‘V-shaped’ implant is made of cobalt chromium covered with a polypropylene tissue with two opening/closing arms. On the inner portion, the clip has two grippers designed to secure the leaflets while being captured during arm closure [36]. The implant has undergone considerable modifications since the first generation in 2003. In 2019, the fourth generation (G4) devices were approved by the FDA including four different types based on two different arm lengths (XT/XTW with 12 mm clip arms and NT/NTW with 9 mm clip arms) and two different arm widths (4 mm for NT/XT and 6 mm for NTW/XTW); furthermore, the grippers of the G4 can be raised or lowered simultaneously or independently, enabling independent grasping of the anterior and posterior mitral leaflets if needed [37]. The delivery system is composed of a 24 French (Fr) steerable guide catheter and the clip delivery system, which has the implant attached to its distal end. The delivery system allows for medial-lateral and anteroposterior steering and in the G4, the system can be attached to a fluid-filled pressure monitoring system to measure real-time left atrial pressure during the procedure [36–38]. As for most of TMVr interventions, the procedure is performed in a hybrid operating room, requiring general anesthesia and intubation due to the need for continuous transesophageal echocardiography to guide the intervention (Figure 1).