Potential applications of ultrasound-derived 3D printed ASD models in ASD occlusion
AS an established alternative to surgical repair, closure surgery of secundum ASD still remains some challenges. The appropriate device can’t always be predicted accurately in advance. Replacement of the occluder occurs occasionally during the operation if the estimated one is too large or too small. Furthermore, in patients with multiple defects, the identification of appropriate candidates for closure and the selection of surgical approach are important. Though single device in the largest defect to occlude the entire defect remains optimal strategy25, it is still technically challenging because of inability to determine the target defect for catheter passage and occluder selection pre-operation, which highlight the necessity of comprehensive evaluation of the ASD parameters and preoperative simulation operation for successful device closure. This study showed a high correlation between the ASD parameters measured from the 3D printed ASD models and the size parameters of intraoperative occluders, among which the circumference of 3D printed models resulted to be most relevant to the occluder device size. 3D printed ASD models can mimics the “en face” view for evaluating the morphological characteristics of an ASD comprehensively and provide reference for determine individualized plans in ASD occlusion 26.
In this preliminary study, the rubber-like material was used to make the 3D models, it can mimics the deformation of ASD structure after device implantation well. On this basis, the ASD 3D printed models were utilized as an intuitive tool for selection of desired occluder during the experiments in vitro. The device size was adjusted based on the parameter measured from 3D printed models and changes of morphological of ASD after the ASO implantation. As a result, the size of ASO selected according to the simulation operation was consistent with the one that actually applied in individualized ASD occlusion. In this simulation operation, if only taking the maximal diameters into consideration, the devices would be undersized or oversized. Associated with the correlation analysis results, other parameters as the minimum diameter and circumference were also taken into account. As a result, the desired occluders were implanted in the 3D printed models successfully, which had the same size as the one utilized in actual operation. In biforate ASD case, the whole size and shape of the two holes were the reference to the determination of appropriate occlude, the optimal target defect and device size was selected through several experiments in vitro in the tangible-patient specific model. The simulation operation indicated that the 3D printed ASD model based on echocardiography has a great potential for integration into clinical practice to assist with device selection and decision-making.