DISCUSSION
The development of aortic insufficiency in patients with LVAD is a common phenomenon – approximately 25-30% of patients develop this complication within one year6. This is likely the result of distorted valve function and reversal of flow dynamics across the aortic valve as a result of the LVAD device6. The development of aortic insufficiency results in increased heart failure symptoms, as well as a decrease in the efficacy of LVAD devices5. The risks associated with surgery have led surgeons to attempt less invasive procedures to treat aortic insufficiency in this population. The challenges present with a single valve TAVR include large annular diameter which cannot be properly covered by the Medtronic valve alone, inadequate access to a stable valve landing zone, and the potential for accelerated degeneration of transcatheter valve leaflets due to elevated heart pressures1.
In addition, this method was successful in reversing hemodynamics and the first valve served as a landing zone since there was a lack of valve calcification for the expandable valves to latch onto. Thus, valve malpositioning has been reported in up to 33% of patients7. In one study, 17% of patients required a second valve implantation, as seen in both patients in this report8. Despite precise measurements for implantation of the valve, mispositioning occurred because of unforeseen factors. For this reason, the second valve is implanted to decrease the risks and create a more sustainable solution for the insufficiency. The benefits of using a Medtronic valve was for positioning in the perfect location, as well as having the option to reposition the valve, if needed. The Edwards valve was used as the second valve because the overexpansion capacity could push the Medtronic valve towards the annulus and anchor the Edwards valve in the right position at the same time.
In previous studies, newer bioprosthetic heart valves have higher success rates than older generation valves8. However, even with the newer generation bioprosthesis used in this report, both Medtronic valves underwent migration, requiring second device implantation. It should be noted that in both cases Medtronic valves were attempted first, followed by Edwards valves. A previous study showed that under- and over-sizing of Evolut valves specifically leads to increased risk of device malpositioning. It was speculated in this study that this was due to the flared design of the Evolut models, which increases the risk of migration in non-calcified valves7. In these cases, however, the Medtronic valve provided a landing zone in the ascending aorta while the Edwards SAPIEN valve in turn provided greater internal forces, which helped to sufficiently stop the inappropriate backflow across the valve because of the maximized radial forces. Both together yield a sustainable solution that can be used in the future in similar cases of aortic insufficiency.
Previous studies done on the VIV TAVR technique bring up the possibility of increased stroke risk because of the manipulation of the atheromatous aorta, the hemodynamic instability which occurs during a procedure, and the possibility of stasis and nonlaminar blood flow around the second implanted valve4. These risks will have to be evaluated in the current cases as time goes on. A larger group of VIV implantations must be done to truly ascertain what risk may be present.
We recognize that the VIV in TAVR approach poses an increase in the immediate financial costs for the procedure, since two prosthetic valves must be used instead of one. The possibility of treating a prohibitive surgical risk patient with this catheter-based therapy may provide long-term benefits of durability and stability that could outweigh the initial costs. Many of the challenges faced by a single valve TAVR are addressed and improved upon with a second valve. The findings of this case study indicate that using TAVR for treatment of aortic insufficiency is feasible; however, surgeons should plan for the likely indication for valve-in-valve implantation.