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OBJECTIVE: Implantation of an annuloplasty ring is an essential component of a durable mitral valve repair. The commonly used off-the-shelf rings do not account for the individual variability of the mitral annulus anatomy. Based on the availability of 3D imaging modalities with sufficient resolution and accuracy for modeling the mitral annulus, the concept of a patient-specific annuloplasty (PSA) ring was developed. In an acute animal study the whole process of image acquisition, ring modeling, production by rapid prototyping, and implantation was performed. The objective of this feasibility trial was to proof the concept of PSA.
Methods: ECG-gated CT-Angiography (CTA) was performed in six healthy pigs. The 3D shapes of the mitral annuli were extracted from the CTA images. Based on the individual shape of the mitral annulus in systole, a solid ring with integrated suturing holes was modeled for each pig. The rings were produced out of a biocompatible titanium alloy using rapid prototyping technology. Each ring was implanted through a left sided thoracotomy using cardiopulmonary bypass (CPB) on the beating heart. After closure of the left atrium, the animals were weaned off bypass and valve function was assessed by echocardiography.
Results: The modeled ring shapes differed strongly from any annuloplasty ring available on the market. All ring matched the annuli and valves appeared competent in Echo after implantation. One out of six rings showed a slight deviation from the circumference macroscopically. CPB time was between 45 and 55 minutes. Ring suturing time was comparable to conventional rings but no time for sizing was necessary.
Conclusions: Planning, production, and implantation of individually built annuloplasty rings is feasible. Image quality and accuracy of the extracted annular models are sufficient for providing a basis for modeling and rapid prototyping of mitral rings. The chosen design consisting of a solid, biocompatible titanium alloy ring with embedded suturing holes ensured firm implantation and facilitated positioning of the ring.