Advances in aortic valve-preserving
surgery
Classification of the etiology of
AR
Previously, surgeons did not have a good understanding of the
pathophysiology of AR. In 2009, classification of the etiology of AR was
proposed by the Brussels group following Carpentier’s classification of
the etiology of mitral regurgitation (Fig. 5)22. Heart
teams then had a common language resulting in a better understanding of
the pathophysiology of AR, which appears beneficial in improving the
outcome of AVP23. The varied phenotypes of bicuspid
aortic valve (BAV) have complicated further understanding of the
pathophysiology of AR. Although widely used, Sievers’ classification of
BAV phenotype is an anatomical classification according to the number of
raphe (0 – 2) and is not practical for AVP (Fig.
6A)24. The Brussels and Homburg groups recently
proposed a repair-oriented classification system based on the commissure
angle (Fig. 6B)25. This is also anticipated to improve
the outcome of AVP for BAV.
Objective assessment of cusp
configuration
The post-repair cusp configuration had traditionally been assessed
subjectively (i.e., by eyeballing). In 2006, Schäfers advocated
measuring the height difference between the central free margins and the
aortic insertion lines using a dedicated caliper (i.e., effective
height) (Fig. 7)26. This novel concept has made
assessment of the cusp configuration more objective and reproducible.
Lansac and colleagues reported that systematic cusp effective height
assessment was associated with not only an increased rate of AVP but
also improvement of repair durability27. In 2013,
Schäfers published the normal dimensions of human cusps, in particular
the cusp height (i.e., geometric height)28. They
defined retraction in adults as a geometric height ≤ 16 mm in tricuspid
aortic valves and ≤ 19 mm in the BAVs, and recommended avoiding AVP in
such cases. This concept has served as a useful basis for decision
making in AVP. Recently, Komiya and colleagues suggested that patients
with a small cusp size (geometric height < 16 mm) can be
candidates for AVP by tight annuloplasty because these cases have
“annulus cusp mismatch”29. However, cases with
severe mismatch may not be appropriate candidates for AVP. They also
emphasized that annular size reduction may be mandatory even in cases
with large cusps when “annulus cusp mismatch” exists.
Advent of aortic
annuloplasty
The most distinct difference between MVP and AVP had been the
availability of annuloplasty in the former. In 1958, Taylor and
colleagues performed external suture annuloplasty for 11 beating hearts.
However, this technique was not widely adopted due to unfavorable
outcomes30. In 1966, Cabrol and associates proposed
subcommissural annuloplasty, which was widely adopted because of its
simplicity31. However, inhomogeneous plication
negatively affects cusp movement and emerged as a risk of
recurrence32. Circular annuloplasty procedures, such
as external suture annuloplasty33, external ring
annuloplasty27, and internal ring
annuloplasty34, have been applied clinically in
experienced centers, and appear to improve clinical outcomes of AVP
(Fig. 8). Please refer to another systematic review article for many
other alternatives35.
Valve-sparing root
replacement
Two innovative approaches were developed to treat aortic root
enlargement with or without AR; David and Feindel proposed
reimplantation of the aortic valve (hereinafter referred to as
reimplantation) in 199236 and Sarsam and Yacoub
advocated remodeling of the aortic root (hereinafter referred to as
remodeling) in 1993 (Fig. 9)37. Then, valve stability
after VSRR has improved dramatically and selection of VSRR among aortic
root surgery procedures has become more common, as described before. The
two approaches had both advantages and disadvantages, but they have been
improved by a number of modifications38 – 40.
Currently, reimplantation using a vascular prosthesis with neosinuses
and remodeling with annuloplasty have become standard procedures and
achieved reproducible outcomes27, 41, 42.