New Insights and Perspective on Bioprosthetic Valve Fracture From Bench Testing and Computed Tomography Analysis

Background

Bioprosthetic valve fracture (BVF) during valve-in-valve TAVR (transcatheter aortic valve replacement) is a procedural adjunct designed to optimize the expansion of the transcatheter heart valve and reduce patient-prosthesis mismatch by using a high-pressure balloon to intentionally fracture the surgical heart valve (SHV).

Methods

We performed bench testing on 15 bioprosthetic SHV to examine the optimal balloon size and pressure for BVF. We assessed morphological changes and expansion of SHV by computed tomography angiography. Successful BVF was defined as balloon waist disappearance on fluoroscopy and/or sudden pressure drop during balloon inflation.

Results

Nine valves met the definition of BVF, 3 of which were confirmed by disruption of the stent frame. We classified surgical valves into 3 subsets: 1) fracturable with metal stent frame (MSF), 2) fracturable with polymer stent frame (PSF) and 3) nonfracturable. In general, valves with MSF were fractured using a balloon size = true internal diameter plus 3-5 mm inflated at high pressure (16-20 ATM) whereas valves with PSF could be fractured with a balloon size = true internal diameter plus 3-5 mm and lower balloon pressure (6-14 ATM). Gains in computed tomography angiography derived inflow area after BVF were 12.3% for MSF and 3.6% for PSF SHV.

Conclusions

Gains in CT-determined valve area after BVF depend on the physical properties of the SHV, which in turn influences pressure thresholds and balloon sizing strategy for optimal BVF. Elastic recoil of PSF valves limits the gains in inflow area after BVF.