Conclusions
Infective endocarditis is associated with high morbidity and mortality
in spite of efforts for earlier diagnosis and advances in antibiotic
treatment (3, 7-10). The use of homografts has been promoted for the
treatment of IE as some evidence suggests a lower risk of recurrent
infection especially in cases of PVE (8-13). Analysis of our ten-year
experience with the use of homografts for aortic root reconstruction in
complex endocarditis showed that this operation may be performed safely,
with low associated operative mortality and morbidity and with excellent
mid-term freedom from recurrence and reoperation. Also, our data
suggests that despite its complexity, homograft aortic root replacement
can be safely taught to residents and early staff surgeons in
cardiothoracic training programs, with a few key provisos.
Arguments against the use of homografts include lack of prompt
availability, a technically more challenging operation, specific
surgical expertise, and increased potential for perioperative morbidity
and mortality (14). Furthermore, there are concerns regarding its
long-term durability and difficult reoperation scenarios due to extreme
late conduit calcification (4, 15, 16). On the other hand, homografts
have superior hemodynamics, a low incidence of thromboembolic
complications and do not require permanent anticoagulation. Endocarditis
with advanced root involvement may present with challenging anatomical
lesions, such as fistulae, extensive destruction of the fibrous
skeleton, and aorto-ventricular discontinuity. In such cases, homografts
may greatly facilitate surgical reconstruction of the left ventricular
outflow tract due to superior tissue pliability and apposition versus
other rigid synthetic materials, excellent hemostatic properties, and
the presence of the donor anterior mitral leaflet, which may be used
during repair (17). Our series readdresses some of these aspects.
Early mortality in endocarditis with root abscesses have been reported
in the range of 13-25% (3, 7-10, 14, 17). This is likely secondary not
only to the severity of the condition but also to the extensive surgical
procedures that are necessary (13, 18). In our series of 54 consecutive
patients operated for root abscess, we had no early deaths, which we
attribute to a combination of early intervention, aggressive
debridement, meticulous attention to myocardial protection and
hemostasis, and impeccable intensive care unit management. The survival
estimate at 1 year and 7 years was 82% and 70%, respectively. Notably,
60% of the late deaths occurred within the first year after the
operation. For the same time period, rate of reinfection and need for
reoperation were 1.8% and 5.6% respectively. Our reinfection rate is
low when compared to other similar series (7, 8, 10). We again attribute
that to our policy of aggressive debridement, early surgical
intervention and the choice of homograft use. In the literature, there
is higher incidence of reinfection within the first year after the
operation and that this is commonly associated with same organism
infection or culture negative infections (7, 8, 11). In our series, the
only reinfection case was also caused by the same organism present at
the initial operation.
As with any type of biological heart valve substitute, structural valve
degeneration is an expected late complication. At late follow-up 2
patients (5.6%) patients required a reoperation on the aortic position.
One was due to stenosis and the second was due to late leaflet
perforation. For those who required reoperations, the degree of
calcification noted in the aortic homograft conduit did not impose
additional difficulty and did not translate into additional mortality.
We believe that with proper planning and careful surgical technique,
reoperations can be carried out safely with results comparable to
reoperation from other procedures. Moreover, the more recent
introduction of decellularization techniques have been very promising in
decreasing the degree of calcification of implanted homografts (19).
There are a few important provisos when interpreting our comparable
outcomes by the mentees. Firstly, the outcomes must be viewed in context
of the overall experience of the senior surgeon who performs 50-100
aortic root operations annually with operative mortality for cumulative
experience of more than 600 Ross operations reported at less than 1%
(20). It is unlikely that our experience could be easily replicated by a
surgeon performing low volumes of aortic root surgery. Secondly, the
responsible surgeon dictates whether aortic root surgery may be taught
to residents/early staff surgeons without compromising patient outcomes.
The surgeon must not only be able to perform aortic root surgery to a
high standard but also be practiced enough to do this by assisting a
more junior surgeon from the left-hand side of the table in such way
that the flow of surgery remains efficient. Lastly, the teaching surgeon
must precisely match case complexity to menteeās competencies. While
some important variables that might dictate whether the case should be
performed by the attending surgeon such as requirement of radical
aorto-mitral curtain reconstruction were included in our analysis, some
other factors are not accounted for such as extreme frailty, difficult
exposure, or tissue friability that are equally important in the
decision making. Similarly, our broad categorization of mentees based on
the postgraduate year may provide little insight into the nuances of
skills assessment required to be capable of safely performing the
complex root surgery.
The main limitations of this study include the absence of a control
group, precluding the more accurate assessment of comparative
effectiveness of the homograft repair against other alternatives such as
a prosthetic valved conduit or other surgeons. Additionally, negative
findings in the relatively small sample size and limited follow-up need
to be interpreted in context.
In conclusion, our study suggests that the use of homograft for aortic
root reconstruction in complex aortic root endocarditis provides
excellent early and mid-term outcomes and can be taught to residents or
early staff surgeons by a surgeon with sufficient depth of both surgical
and teaching expertise.