Discussion
Mitral valve repair has been increasingly utilized for the surgical
treatment of active infective endocarditis because of its low early
mortality rate and long-term outcomes exceeding those of mitral valve
replacement [1]. However, mitral valve replacement is sometimes
required for profoundly extensive and destructive active infective
endocarditis of the mitral valve, for which mitral valve reconstruction
is extremely challenging. Especially in young patients, mechanical
mitral valve replacement is usually the standard procedure, after which
lifelong anticoagulation with warfarin is mandatory to avoid stroke and
systemic embolization. Some authors have reported extensive
reconstruction of the mitral valve leaflets and chordae using autologous
or bovine pericardium with or without chordal reconstruction for such
devastating cases. These reports described only the short- or mid-term
results; the long-term outcomes remain unclear because the durability of
the pericardial leaflet is still controversial [2-5]. Furthermore,
these reports included repair for chronic endocarditis, whereas repair
for active endocarditis may be more challenging. Therefore, in this
study, we aimed to clarify the long-term results of extensive mitral
valve leaflet reconstruction with autologous pericardium focusing only
on active infective endocarditis. Ito et al. [6] described 25
patients who underwent seamless reconstruction of the mitral leaflet and
chordae with one piece of pericardium and demonstrated good short- and
mid-term outcomes. In their observational study, only 6 of 25 patients
had active endocarditis. The repaired lesion was the posterior leaflet
together with its chordae (n = 3) and the commissural leaflet (n = 3).
In our study, all five patients had active endocarditis. The anterior
leaflet was included with the repaired leaflet in three patients in whom
large autologous pericardium and several artificial chordae were placed.
In the present study, echocardiographic follow-up was performed at a
mean of 80 months (range, 7–111 months) postoperatively, whereas it was
performed at a mean of 9.7 months in the study by Ito et al. [6].
Mitral regurgitation recurred in one of our five patients and similarly
in one of six patients with active endocarditis in the study by Ito et
al. [6] for the same reason (detachment of the pericardial suture
line).
Another crucial issue is the durability of the autologous pericardium
when implanted as part of the valve leaflet and whether the autologous
pericardium should be treated by glutaraldehyde. Shomura et al. [7]
reported good results with a mean follow-up of 4.5 years after mitral
valve repair with glutaraldehyde-treated autologous pericardium in 139
patients, including 32 with active infective endocarditis (the 10-year
rate of freedom from reoperation was 82%). Although the results for
patients with only active infective endocarditis and the details of the
surgical procedures (e.g., major or partial leaflet reconstruction and
with or without chordal implantation) were not clear, this report
demonstrated that the mid-term durability of glutaraldehyde-treated
autologous pericardium might be favorable. Glutaraldehyde treatment may
reportedly improve the durability of the reconstructed pericardium
leaflet, providing a lower rate of calcification, shrinkage, or
disruption than fresh autologous pericardium [8, 9]. In contrast,
however, some reports have indicated that glutaraldehyde treatment might
be associated with pericardial calcification [10,11]. Excellent
long-term outcomes of mitral valve leaflet repair using fresh autologous
pericardium were recently reported (89% per 10 years of freedom from
reoperation) [11]. This report demonstrated that glutaraldehyde
treatment of the pericardium might be associated with late calcification
and mitral valve stenosis due to leaflet thickening and loss of
pliability. A conclusion has not yet been reached about the durability
of the pericardium and how to manage the pericardium to obtain a good
long-term result; however, minimum use of the pericardium should be
desired. We believe that the chordae should be reconstructed not by
using pericardium as described by Ito et al. [6] but by using
artificial chordae (polytetrafluoroethylene sutures) to decrease the use
of pericardium as much as possible. Furthermore, implantation of
artificial chordae is a widespread and familiar technique for many
cardiac surgeons. Instead of immediate mitral valve replacement, our
technique of mitral valve repair is worth trying especially in young
patients with profoundly extended and destructed active infective
endocarditis.