Morphological Evaluation of Mitral Valve Based on Three-dimensional Printing Models: Potential Implication for Mitral Valve Repair

Abstract

Objective: This study aimed to analyze the morphological characteristics of rheumatic (RMVD) and degenerative mitral valve diseases (DMVD) based on three-dimensional (3D) printing model before and after surgery and to explore the potential implication of the 3D printing model for mitral valve (MV) repair.

Methods: 3D transesophageal echocardiography (TEE) data of the MV were acquired in 45 subjects (15 with RMVD, 15 with DMVD, and 15 with normal MV anatomy). 3D printing models of the MV were constructed by creating molds to be printed with water-soluble polyvinyl alcohol, then filled with room temperature vulcanizing silicone. The parameters of the annulus and leaflet of the MV were acquired and analyzed using the 3D printing model. Mitral valve repair was simulated on 3D printing models of 10 subjects and compared with the actual operation performed on patients. The effects of surgery were assessed by evaluating the changes in coaptation length (CL) and the annular height to commissural width ratio (AHCWR) before and after MV repairs. The correlations of the grade of mitral regurgitation with CL and AHCWR were analyzed.

Results: 3D silicone MV models were all successfully constructed based on 3D TEE data. Compared with the normal groups, the mitral annulus size in the RMVD groups showed no significant differences. In contrast, mitral annulus in DMVD groups was dilated and flattened with diameters of anteroposterior, anterolateral-posteromedial, commissural width, annular circumferences, and area increased. Mitral repair was successfully simulated on 10 models with significant increase in leaflet coaptation area both in vivo and in vitro. Good agreement was observed in CL and AHCWR after surgery in the 3D printing model compared with real surgery on the patient valve. The grade of mitral regurgitation correlated inversely with CL (r = –0.87, P < 0.01) and AHCWR (r = –0.79, P < 0.01). Mitral valve repair was performed twice in one model to assess which provided a better outcome.

Conclusions: 3D printing models of the MV based on 3D TEE data could be used in morphological analysis of the MV before and after surgery in RMVD and DMVD. Surgery simulation on 3D printing models could provide valuable information concerning morphological changes after surgery, with are closely associated with clinical outcomes.