Discussion
Rapid deployment valves, such as the Intuity Valve, have allowed easier
replacement through a simplified procedure with shorter cardioplegic
arrest and cardiopulmonary bypass times. (1,4) In this study we would
like to share our experience with the value of intraoperative
echocardiography in predicting the size of rapid deployment valves in
the aortic position. One of the main concerns of the so-called
sutureless or rapid deployment valves is the theoretical possibility of
paravalvular leak given the fact that only 3 guiding sutures are needed
for this type of bioprosthesis. When done correctly the risk of the
above is small. In the TRANSFORM study, the investigators reported a
6.9%, 1.2%, and 0.4% incidence of mild, moderate and severe
paravalvular leak respectively at 1 year follow up echocardiography.
(table 1)
During “sutured” aortic valve replacement, the surgeon places 12-15 or
sometimes even more sutures around the annulus. This is a form of
“annuloplasty”, because the prosthesis is circumferentially
“pulling” the annulus towards itself and as a result a small undersize
of a prosthesis is much more forgiving compared to rapid deployment
valves. In rapid deployment valves, sizing the valve appropriately is of
paramount importance. A critical step here is meticulous decalcification
of the aortic annulus. Inappropriate decalcification will lead to valve
under-sizing. The calcium will prevent the “barrel” end of the sizer
to advance to the intra-annular plane and this will be misinterpreted as
“too big of a valve”, when what really happens is that an eccentric
piece of calcium inhibits the sizer to advance to the appropriate level.
This is more common in minimal access cases where visibility can
sometimes be inadequate. TEE is a very useful tool that Cardiac Surgery
teams have at their disposal. It is in fact a quality measure that
should be applied during valve surgery. Although at the beginning of our
experience with Intuity valves we skipped documenting intraoperative
annular measurements, now we always measure the annulus. We found this
to be very helpful in predicting the valve size to be used. 27 % of our
patients received a valve that was smaller than the annular measurement.
Most of these operations were performed during our early experience with
rapid deployment valves. Currently, time we tend to place valves
that are equal or larger than the annular measurement. In fact, the mean
size valve implanted was 23.3 mm which is 0.9 mm greater compared to the
mean annular size of 22.4 mm. When the annulus measures between valve
sizes, i.e 24 mm, we always try to implant a size up which in this case would
be 25 mm. There was one case of new pacemaker implantation. This patient
had an annulus measured at 26 mm and we placed a 27 mm Intuity valve.
The patient did not have preoperative bundle branch block and perhaps
one should be less aggressive with oversizing when implanting a bigger
Intuity valve. Overall however the incidence of pacemaker implants in
this series was 4% which is favorable. The Intuity Valve system uses
the well-proven performance and longevity of the Carpentier- Edwards
Perimount Magna Ease (Edwards Life Sciences LLC, Irvine, Calif)
Bioprosthesis and the newly developed rapid deployment technology. This
combination provides surgeons with a novel tool that may minimize
operative times and simplifies the procedure. There is a learning curve
and some important steps that are critical for successful deployment.
TEE is perhaps one of our greatest allies in this process: it can
further enhance valve sizing and guidance through a proper and safe
deployment. Although evident in our experience, larger scale studies are
needed to further elucidate conclusions on the importance of avoiding
under-sizing valves.