Minimally invasive surgeries have numerous advantages, yet complications may arise from limited knowledge about the anatomical site targeted for the delivery of therapy. Transcatheter aortic valve replacement (TAVR) is a minimally invasive procedure for treating aortic stenosis. Here, we demonstrate multimaterial three-dimensional printing of patient-specific soft aortic root models with internally integrated electronic sensor arrays that can augment testing for TAVR preprocedural planning. We evaluated the efficacies of the models by comparing their geometric fidelities with postoperative data from patients, as well as their in vitro hemodynamic performances in cases with and without leaflet calcifications. Furthermore, we demonstrated that internal sensor arrays can facilitate the optimization of bioprosthetic valve selections and in vitro placements via mapping of the pressures applied on the critical regions of the aortic anatomies. These models may pave exciting avenues for mitigating the risks of postoperative complications and facilitating the development of next-generation medical devices.
Background: There is no effective method to predict paravalvular regurgitation prior to transcatheter aortic valve replacement (TAVR). Methods: We retrospectively analyzed pre-TAVR computed tomography (CT) scans of 20 patients who underwent TAVR for severe, calcific aortic stenosis and subsequently printed 3-dimensional (3D) aortic root models of each patient. Models were printed using Ninjaflex thermoplastic polyurethane (TPU) (Ninjatek Manheim, PA) and TPU 95A (Ultimaker, Netherlands) on Ultimaker 3 Extended 3D printer (Ultimaker, Netherlands). The models were implanted at nominal pressure with same sized Sapien balloon-expandable frames (Edwards Lifesciences, CA) as received in-vivo. Ex-vivo implanted TAVR models (eTAVR) were scanned using Siemens SOMATOM flash dual source CT (Siemens, Malvern, PA) and then analyzed with Mimics software (Materialize NV, Leuven, Belgium) to evaluate relative stent appositions. eTAVR were then compared to post-TAVR echocardiograms for each patient to assess for correlations of identified and predicted paravalvular leak (PVL) locations. Results: A total of 20 patients (70% male) were included in this study. The median age was 77.5 (74-83.5) years. Ten patients were characterized to elicit mild (9/10) or moderate (1/10) PVL, and 10 patients presented no PVL. In patients with echocardiographic PVL, eTAVR 3D model analyses correctly identified the site of PVL in 8/10 cases. In patients without echocardiographic PVL, eTAVR 3D model analyses correctly predicted the lack of PVL in 9/10 cases. Conclusion: 3D printing may help predict the potential locations of associated PVL post-TAVR, which may have implications for optimizing valve selection and sizing.
Background: Today, there is no manufacturer-supplied retrieval tool for the Micra TM pacemaker (Medtronic, Minneapolis, MN, USA); therefore, off-the-shelf catheters have been employed for retrievals. The proximal retrieval feature of the Micra TM can be snared and the device is then retracted from the myocardium, pulling the device through the tricuspid valve. This study characterizes the potential risks of Micra TM nitinol tine engagement with the tricuspid sub-valvular apparatus.Methods: Fresh human hearts nonviable for transplant (n = 10) were obtained from our regional organ procurement agency (LifeSource, Minneapolis, MN, USA). Micra TM fixation tines were affixed to a linear force transducer. Tines were then engaged in tricuspid chordae tendineae to conduct a constant velocity tensile test. Each test was run until tines disengaged from the chordae tendineae or until they released from the valve apparatus. Subsequently, biomechanical failure properties of the valve apparatus and isolated chordae tendineae were determined using a series of uniaxial tensile tests.Results: There were no chordal ruptures observed during our Micra TM tine extraction testing.Chordal failure required 15.0 times the force of extracting a single engaged tine, and 9.0 times the force of extracting two engaged tines. The uniaxial stresses required for isolated chordal failure averaged 17.4 N/mm 2 ; failure strains exceeded 150% resting chordal length.
Conclusions:The forces required to rupture tricuspid chordae tendineae significantly exceeded the forces potentially imposed on the chordae during Micra TM device retrievals. We conclude that the fixation tines of the Micra TM device are unlikely to damage the tricuspid apparatus during either implant or retrieval.
K E Y W O R D Sbiomechanical failure properties, cardiac anatomy, extraction, Micra pacemaker, retrieval, tricuspid valve device interactions
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.