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 mentee’s 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.