Background:

Several LAA occlusion (LAAo) devices have been introduced into the market, with significant differences in device design and structure. Given this fact, biomechanical differences between these devices are very likely, however, no standardized benchmark tests have been introduced.

Aims:

The aim of this study was to introduce and perform in-vitro bench tests of LAA occlusion (LAAo) devices regarding stability and sealing capacity.

Methods and results:

Two LAA occlusion devices, namely the WATCHMAN™ and the Occlutech^® occluder, of three different sizes underwent testing for tug force and sealing capacity in a novel dedicated in-vitro setup.

Tug force measurements were performed in LAA models using bovine aortic tissue to mimic the endo-luminal surface of human left atrial appendages.  Leakage tests were performed in round silicone cylinders of a specific diameter to mimic the landing zone of LAA anatomies. Finally, the influence of device-resheathing on stability and device-conformity were performed simulating intraprocedural conditions.

At baseline, tug force of the WATCHMAN™ devices was significantly higher when compared to Occlutech^® occluders across the entire sizing range of all devices (maximum tug force: 2.6 ± 0.1 N for WATCHMAN™ vs. 1.8 ± 0.1 N for the Occlutech^®; p < 0.01) Repeated resheathing resulted in a reduction in diameter of the WATCHMAN™ devices of max. 7.9% after four times, whereas diameters of Occlutech^® occluders remained unchanged. Device stability was not significantly impacted by resheathing in both devices. At baseline, sealing capacity in a bench-test using silicone LAA-models did not differ between the two devices. However, resheathing lead to an in-vitro loss of sealing capacity of the WATCHMAN™ devices, which increased with each resheathing and resulted in a maximal peridevice leak of 91.1 ± 7.9 %.

Conclusions:

In-vitro, the WATCHMAN™ LAA occluder series showed progressive deformation and increased peridevice leakage after resheathing presumably as a result of diameter reduction. Most likely due to its anchoring mechanism, stability of the WATCHMAN™ was not impaired by resheathing and was significantly higher than that of the Occlutech® device.