TAVR durability

Technical aspects of the lab…

The bioprostheses deployed via transcatheter have unknown durability, since the vast majority of cohort studies have around 8 years of evolution. In order to estimate the durability above that, some services mirror the durability of bioprostheses implanted by conventional means, but we do not have exactly the same mechanical structure between the two devices.

Manufacturers are required to perform over-the-counter tests before releasing a specific prosthesis to the market and the minimum level of the test is equivalent to a number of cardiac cycles present in 5 years of using the bioprosthesis.

Bench tests, the ones conducted outside the human body, that hypothesized 25 years of using the bioprosthesis showed that in the hydrodynamic aspect, the prostheses currently on the market did well and adequately withstand the stress generated. This is similar to that found in the same bench tests as conventional bioprostheses.

Here we request your attention to some interesting aspects, such as the way of release between the prostheses. Those implanted via transcatheter, undergo a crimping and ballooning process, which, in bench tests, ends up not happening exactly as in in vivo. Some aspects of deterioration secondary to this mechanical compression were pointed out, but in these tests there was no negative impact.

Now, we bring the biggest problem of these bioprostheses, which are the local thrombotic phenomena and calcification degeneration secondary to the contact of the leaflets with the plasma and the humoral factors of the human body. This, in practice, shows a very important impact on the durability of the prosthesis, but it is impossible to adequately reproduce this in bench tests.

A second aspect tested on the counter was the implant considered non-nominal, that is, implant in non-circular structures or implants with supra/infra dimensioning. In over-the-counter tests, the prosthesis has behaved normally over 25 simulated years, but in reality this can differ, as turbulent jets associated with humoral factors can accelerate certain deteriorations.

What do the data bring us?

They bring us to the certainty that, from the biomechanical point of view, bioprostheses implanted via transcatheter are built in excellent conditions to resist for more than 20 years, just like the prostheses traditionally used by conventional methods, but the secret, not yet discovered, it is in the resistance to calcific wear generated by the direct contact of the leaflets with the plasma and other humoral components.

Suggested literature:

1 – Sathananthan J, Hensey M, Landes U, et al. Long-Term Durability of Transcatheter Heart Valves: Insights From Bench Testing to 25 Years. JACC Cardiovasc Interv. 2020; 13 (2): 235‐249.

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