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Page 6 of 24 Palacios Mini-invasive Surg 2020;4:73 I http://dx.doi.org/10.20517/2574-1225.2020.72

Severe mitral regurgitation after PMV is a major complication of this procedure. This complication
confers an adverse prognosis and frequently requires intensive treatment and urgent mitral valve surgery.
Although some morphologic features of the mitral valve might increase the risk of severe regurgitation,
echocardiographic evaluation with the Wilkin’s Echo-Sc has been unable to predict it. Padial et al. [25,26]
described a new echocardiographic score that can predict the development of severe mitral regurgitation
after PMV with the double balloon and the Inoue balloon techniques. This score takes into account
the distribution (even or uneven) of leaflet thickening and calcification, the degree and symmetry of
commissural disease, and the severity of sub valvular disease. Thus, echocardiography can identify
patients with a high risk of developing severe mitral regurgitation after PMV using this proposed
mitral regurgitation echocardiographic score [25-27] This new score can help assess the probability of this
complication before the procedure to anticipate the likelihood that surgical repair may be needed. In
addition, it could conceivably be used to select patients for modified procedure techniques that might
[28]
be developed to minimize this complication [25,26] . Anwar et al. used a new real-time three-dimensional
echocardiography (RT3DE) score for evaluating patients with mitral stenosis (MS) and compared with
Echo-Sc. The new RT3DE score was constructed by dividing each mitral valve (MV) leaflet into 3 scallops
and was composed of a total of 31 points (indicating increasing abnormality), including 6 points for
thickness, 6 for mobility, 10 for calcification, and 9 for subvalvular apparatus involvement. The total RT3DE
score was calculated and defined as mild (< 8), moderate (8-13), or severe (≥ 14). Mitral valve morphology
was assessed using the Wilkin’s Echo-Sc and compared with the new RT3DE score. They reported that
the new RT3DE score is feasible and highly reproducible for the assessment of mitral valve morphology
in patients with mitral stenosis and it can provide incremental prognostic information in addition to the
[28]
Wilkin’s Echo-Sc . However, none of the scores available have been shown to be superior to the others.

COMMISSURAL CALCIFICATIONS AND DEGREE OF COMMISSURAL FUSION AND
FEASIBILITY AND EFFICACY OF PMV
Although echocardiographic scores are important for identifying optimal candidates for PMV, there
are other distinctive morphologic features of mitral valve disease whose relationships to outcome after
percutaneous mitral valvotomy are also important. Several scores have been developed that take into
account the uneven distribution of anatomic abnormalities, in particular in commissural areas [7,25-27,29] .
Since commissural splitting is the dominant mechanism by which mitral valve stenosis is relieved by this
technique, commissural morphology may predict outcome. Figure 4 depicts short axis TTE of one patient
with concentric mitral stenosis (right panel) and one patient with eccentric calcification mitral stenosis
(left panel). For example, excessive thickening and calcification of one commissure should be expected
to decrease the effectiveness of the procedure by limiting the splitting of the involved side of the orifice
and predisposing the contralateral commissure to rupture or the normal leaflet to tearing. This could also
potentially predispose to severe mitral regurgitation after PMV [25-27,30] . Patients with evidence of calcium
in a commissure have a lower survival rate and a higher incidence of mitral valve replacement and all
end points combined. Thus, the simple presence or absence of commissural calcification assessed by two-
dimensional echocardiography can be used to predict outcome [25-27,31,32] .

TECHNIQUE OF PMV
The transvenous transseptal approach is the most widely used PMV technique. Transseptal catheterization
is the first step of the procedure and one of the most crucial one. The trans-arerial approach could
represent an alternative in the rare cases in which the transseptal approach is contraindicated or
impossible [33-35] . There are currently two main transseptal PMV techniques, balloon valvuloplasty and
metallic commissurotomy. The two major techniques of balloon valvuloplasty are the double-balloon
technique and the Inoue technique. The double-balloon technique [Figure 5] is effective but demanding
and carries the risk of left ventricular perforation by the guidewires or the tip of the balloons [1,5,6,8,10] . The