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.