A tissue-silicone integrated simulator for right ventricular pulsatile circulation with severe functional tricuspid regurgitation.

There is a great demand for development of a functional tricuspid regurgitation (FTR) model for accelerating development and preclinical study of tricuspid interventional repair devices. This study aimed to develop a severe FTR model by creating a tissue-silicone integrated right ventricular pulsatile circulatory simulator. The simulator incorporates the porcine tricuspid annulus, valve leaflets, chordae tendineae, papillary muscles, and right ventricular wall as one continuous piece of tissue, thereby preserving essential anatomical relationships of the tricuspid valve (TV) complex. We dilated the TV annulus with collagenolytic enzymes under applying stepwise dilation, and successfully achieved a severe FTR model with a regurgitant volume of 45 ± 9 mL/beat and a flow jet area of 15.8 ± 2.3 cm2 (n = 6). Compared to a normal model, the severe FTR model exhibited a larger annular circumference (133.1 ± 8.2 mm vs. 115.7 ± 5.5 mm; p = 0.009) and lower coaptation height (6.6 ± 1.0 mm vs. 17.7 ± 1.3 mm; p = 0.003). Following the De-Vega annular augmentation procedure to the severe FTR model, a significant reduction in regurgitant volume and flow jet area were observed. This severe FTR model may open new avenues for the development and evaluation of transcatheter TV devices.

Repairable ex vivo model of functional and degenerative mitral regurgitation.

OBJECTIVES: Transcatheter mitral valve repair is an emerging alternative to the surgical repair. This technology requires preclinical studies to assess efficacy in mitigating mitral regurgitation (MR). However, ex vivo MR models are not established. We developed 2 novel repairable models, functional and degenerative, which can quantitatively assess regurgitation and effect of intervention. METHODS: We used porcine mitral valves and a pulsatile flow circulation system. In the functional MR model, the annulus was immersed in 0.1% collagenase solution and dilated using 3D-printed dilators. To control the regurgitation grade, the sizes of the dilator and silicone sheet in which the valve was sutured to were adjusted. Chordae of P2 were severed in the degenerative model, and the number of severed chordae was adjusted to control the regurgitation grade. Models were repaired using the edge-to-edge or artificial chordae technique. RESULTS: The mean regurgitant fraction of the moderate-severe functional and degenerative models were 47.9% [standard deviation (SD): 2.2%] and 58.5% (SD: 8.0%), which were significantly reduced to 28.7% (SD: 4.4%) (P < 0.001) and 26.0% (SD: 4.4%) (P < 0.001) after the valve repair procedures. Severe functional model had a mean regurgitant fraction of 59.4% (SD: 6.0%). CONCLUSIONS: Both functional and degenerative models could produce sufficient MR levels that meet the interventional indication criteria. The repairable models are valuable in evaluating the efficacy of valve repair procedures and devices. The ability to control the amount of regurgitation enhances the versatility and reliability of these models. These reproducible models could expedite the development of novel devices.