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.