Discussion
In the present study, a TV with two posterior leaflets was an
independent predictor of additional procedures. The TV consists of
multiple posterior leaflets in about half of patients, and the
morphological diversity of these leaflets has attracted attention among
researchers (10,17,18).
We consider that postoperative TR can be divided into two types: TR
observed immediately after surgery (residual TR) and TR that worsens
during follow-up despite the fact that it was controlled immediately
after surgery (recurrent TR). Fukuda et al. (9) reported that residual
TR soon after the operation causes volume overloading of the right
ventricle and further right ventricular dilatation and dysfunction,
resulting in worsening TR. Therefore, we consider that controlling the
residual TR grade during the perioperative period is crucial to avoid
the development of later TR.
Upon completion of the ring annuloplasty, we routinely checked TV by the
saline test. If residual TR was found, we performed additional
edge-to-edge repair at the sites of the leakage. Although we could
control TR with ring annuloplasty alone in most patients, additional
sutures were necessary to control residual TR in some patients. The
locations and numbers of edge-to-edge repairs varied among the patients
according to the features of the residual TR. Thus, we investigated the
crucial causes of complicated TV repair in our study.
The surgical technique to control TR depends upon the mechanism of TR,
such as annular dilatation, prolapse or tethering of the leaflets, or
right ventricular dilatation. We suspected that morphological
differences of the TV may make it difficult to control TR during
surgery. Therefore, we focused on TV morphology and the complexity, to
control TR. We set the endpoint as whether additional procedures were
needed during the operation. According to the univariate and
multivariate logistic regression analyses, patients with two posterior
valve leaflets required additional procedures for reduction of TR.
Moreover, patients with two posterior valve leaflets had higher TR score
before operation and one year after operation than those with one
posterior valve leaflet. There was no difference in the size of the TV
regardless of the number of posterior leaflets. Considering these
results, we concluded that the presence of two posterior valve leaflets
itself has the potential to increase regurgitation, resulting in the
need for complex procedures in TV repair.
When we classify the morphological diversity of the TV leaflets,
identification of the commissure between the anterior and posterior
leaflets is important. When the TV has two posterior leaflets, the
commissural cleft between the anterior and posterior leaflets is
sometimes misidentified as a deep cleft of the anterior leaflet. This is
because most surgeons do not observe fan-shaped chordae arising from the
anterior papillary muscle and do not recognize that half of patients
have a TV with two posterior leaflets. When surgeons misinterpret the
commissure between the anterior and posterior leaflets, they might
choose a smaller annuloplasty ring and adjust the marker on the ring to
an inappropriate position, especially in patients with two posterior
leaflets. A smaller ring might deform TV annulus and impose more stress
on suture lines. We measured both the distance between the commissure of
the septal leaflet and the area of the anterior leaflet for proper
sizing of annuloplasty ring, resulting in selection of larger ring. To
avoid deformation of the TV, we applied the “shoulder point fitting
method” of proportional annuloplasty in all patients (18). The shoulder
point is defined as the 2-o’clock position of the TV annulus, where the
TV annulus is more widely dilated. This technique has a lower risk of TV
annulus deformation because annuloplasty is performed toward the
shoulder point (18). This method also supports patients with multiple
posterior leaflets. We are convinced that proportional annuloplasty was
achieved in all patients regardless of the number of posterior leaflets
in this study.