Standardization of aortic valve-preserving surgery
Due to the long learning curve, as mentioned above, standardization of
AVP has been attempted. Lansac pioneered the standardized approach for
VSRR using a graft with neosinuses for remodeling because it was
originally designed to perform remodeling operation (Fig.
8B)43. It sets three commissures at the same height
and symmetric angle, and thus has less risk of distorting valve
geometry. It was emphasized, however, that resultant discrepancy of
effective height of each cusp should be aggressively corrected for
better cusp durability, as described above27. He
launched a multicenter study of remodeling, and thus the quality of AVP
should be reproducible between institutions44, 45.
His group also clarified that additional stabilization of the
sinotubular junction (STJ) (i.e., double ring annuloplasty) is
associated with better outcome compared to single external ring
annuloplasty. They also intended to standardize this approach by
indicating criteria for choice of the both ring
sizes46. They recommended the same ring size for the
annulus and STJ. In general, postoperative annulus diameter becomes
smaller than external ring size because of the ventricular muscle
thickness (3.3 – 6.2 mm)47. Recent echocardiographic
analyses indicated that the ratio of annulus diameter to STJ diameter in
normal subjects is approximately 1:1.1 – 1:1.248.
Therefore, their standardized approach may restore normal root geometry.
Another experienced center selected a tube graft for remodeling
automatically according to the body surface area of the patient followed
by annuloplasty for one size smaller than the graft size, which will
also create a reasonable root configuration42. For
reimplantation, the Brussels group chose a graft with neosinuses
corresponding to the commissure height between the left and non-coronary
sinus, because commissure height remains relatively
constant49.
We have also made efforts to standardize remodeling
techniques50. We set the target annulus diameter based
on the average annulus diameter for each body surface
area51 and choose a one-size larger tube graft. Each
scallop of the graft corresponding to the Valsalva sinus is cut using
our original template (Fig. 10A). Commissure height and angle are
symmetrically arranged using our original sizer (Fig.
10B)50. Finally, the effective height of each cusp is
adjusted to the same level. We hope that these strategies for
standardization will improve long-term durability of the repair and AVP
will be adopted more widely.