Adult: Aortic Valve: Evolving Technology
Effect of leaflet laceration on transcatheter aortic valve replacement fluid mechanics and comparison with surgical aortic valve replacement

https://doi.org/10.1016/j.jtcvs.2023.03.006Get rights and content

Abstract

Background

Leaflet thrombosis after surgical aortic valve replacement (SAVR) and transcatheter aortic valve replacement (TAVR) may be caused by blood flow stagnation in the native and neosinus regions. To date, aortic leaflet laceration has been used to mitigate coronary obstruction following TAVR; however, its influence on the fluid mechanics of the native and neosinus regions is poorly understood. This in vitro study compared the flow velocities and flow patterns in the setting of SAVR vs TAVR with and without aortic leaflet lacerations.

Methods

Two valves, (23-mm Perimount and 26-mm SAPIEN 3; Edwards Lifesciences) were studied in a validated mock flow loop under physiologic conditions. Neosinus and native sinus fluid mechanics were quantified using particle image velocimetry in the left and noncoronary cusp, with an increasing number of aortic leaflets lacerated or removed.

Results

Across all conditions, SAVR had the highest average sinus and neosinus velocities, and this value was used as a reference to compare against the TAVR conditions. With an increasing number of leaflets lacerated or removed with TAVR, the average sinus and neosinus velocities increased from 25% to 70% of SAVR flow (100%). Diastolic velocities were substantially augmented by leaflet laceration. Also, the shorter frame of the SAVR led to higher flow velocities compared with the longer frame of the TAVR, even after complete leaflet removal.

Conclusions

Leaflet laceration augmented TAVR native and neosinus flow fields, approaching that of SAVR. These findings may have potential clinical implications for the use of single or multiple leaflet lacerations to reduce leaflet thrombosis and thus potentially improve TAVR durability.

Section snippets

In Vitro Flow Loop

To characterize the fluid mechanics of TAVR and SAVR, a validated pulsatile left heart flow simulator with coronary flow modeling capability12 was utilized. To be able to have optical access to the model, a fluid with the same viscosity as blood was used, which consisted of a water-glycerin solution with 36% glycerin by volume. A previously utilized model of the aortic root with 3 sinuses, based on post-TAVR averaged human aortic root dimensions12 was present. To simplify the model, only 1

Summary of Flow Experiments

Figure 4 shows a bar graph summary of the results of the different flow experiments when imaging the native sinus regions for the simulated SAVR and TAVR scenarios. With increasing leaflet laceration or leaflet removal, the average sinus velocities continued to increase. The SAVR model had the highest average sinus velocities and was used to normalize the results. Velocities in the LCC were higher than the NCC for all conditions, except with single leaflet laceration of the NCC. Figure 5 shows

Discussion

In this in vitro study of fluid mechanics in the native and neosinus regions following SAVR and TAVR, we observed the following: SAVR provided the highest flow in both the native- and neosinus regions; in the setting of TAVR, modifying any native leaflet improved flow in both the sinus and neosinus regions, even in the cusps without lacerated leaflets; with an increasing number of modified leaflets, there was a stepwise improvement in flow in all sinus and neosinus regions measured; and there

Conclusions

Aortic leaflet laceration and removal augmented TAVR native- and neosinus flow velocities, approaching that of SAVR. Dedicated devices to facilitate leaflet modification and clinical trials that study their role in preventing leaflet thrombosis may influence lifetime valve management.

Cited by (0)

View full text
© 2023 by The American Association for Thoracic Surgery