Novel Resectable Myocardial Model Using Hybrid Three-Dimensional Printing and Silicone Molding for Mock Myectomy for Apical Hypertrophic Cardiomyopathy

Fig. 1. The development of the resectable myocardial model using 3D printing was divided into two stages. A. First, ECG-gated CT was performed, and the end-diastolic phase of the CT image was segmented into cardiac chambers and vessels to generate a STL file. The STL file was transferred to a computer-aided design, which included the additions of offsetting and contour, implementing support structures, and modeling of the inlet and outlet for silicone injection into the molding of the LV myocardial mass. B. Second, 3D printing of anatomic structures, such as the aorta, right ventricle, and coronary arteries, as well as the molding of the LV myocardial mass and the internal and external support structures, were performed. After assembling the 3D printouts, silicone was injected into the LV molding using an injection gun, followed by a drying process that lasted 24 hours. ECG = electrocardiography, LV = left ventricular, STL = standard tessellation language, 3D = three-dimensional

Fig. 2. Representative photographs show the transaortic (A) and transapical (B) approaches simulated during mock surgery using a myocardial model. Intraoperative photographs show the surgeon's view during transaortic resection (C) and transapical resection (D) the finally resected specimens using each approach for patient 1. Photographs captured from the intraoperative arterial waveform monitor of the radial arterial line before (E) and after (F) myectomy show increased area under the curve of the arterial waveform after surgery, which may reflect improved stroke volume. AV = aortic valve

Fig. 3. Representative CT images obtained from the myocardial model (A, C) verify the structural consistency of the myocardial model compared with that of the cardiac CT images (B, D) of patient 2 and patient 3. However, the apical segments and the apex of the myocardial model of patient 3 were relatively thicker than those shown by cardiac CT (C). AO = aorta, LV = left ventricle, PM = papillary muscle

Fig. 4. Representative images from the STL file generated for patient 2 show the LV myocardial mass and its internal support structure, aorta, and coronary arteries (A). Based on this STL file, three-dimensional printing of anatomic structures, support structures, and molding for the LV myocardial mass were performed (B). After silicone injection into the LV mold followed by a drying process, a mock transapical myectomy was performed, and the anatomic relationship between the cardiac apex and coronary artery was demonstrated in the photograph (C). Intraoperative photography via the transapical approach shows the limited visual field of the LV cavity (D). LAD = left anterior descending artery, LV = left ventricular, STL = standard tessellation language

Fig. 5. Representative photograph shows the myocardial model of patient 3 using hybrid three-dimensional printing and silicone molding (A). A mock transapical myectomy was performed (B), and the excised pieces of silicone were outlined within the dotted line (C). Intraoperative photography obtained during transapical myectomy show a similar field of view compared with that of mock surgery (D). D = diagonal branch, LAD = left anterior descending artery, RV = right ventricle