Percutaneous Transluminal Mitral Valvuloplasty
Percutaneous transluminal mitral valvuloplasty (PTMV) changed the
approach of cardiothoracic surgeons to mitral stenosis. The technique
was developed by Inoue in 1984 but has since been refined. Anatomically,
PTMV is of greatest use in patients with the pliability of the mitral
valve, clear of substantial calcification or
fibrosis.40,41. Suitability of this technique for
mitral stenosis can be determined through the application of Abascal’s
echocardiographic scoring system. Also known as the Wilkins score, it is
essential in its application as it can predict mitral regurgitation
following an intervention. The criteria evaluate four key aspects to
valvular morphology outlined in Table 2. With respect to the Wilkins
criteria, a higher score specifies a more progressed disease and a
reduced chance of success with this technique. Surgical mitral valve
replacement is recommended for patients in those in which PTMV is not
anatomically optimal.42 The surgical basis is via
balloon valvuloplasty, this balloon is applied crossing the mitral valve
thereby improving leaflet excursion and orifice diameter. The operation
is critical in the treatment of rheumatic heart disease as it fractures
the rheumatic fusion that has developed. It is also a reliable therapy
management option for pregnant women.43
The 1984 paper by Inoue and colleagues was revolutionary as the
technique developed allowed mitral commissurotomy without thoracotomy.
Post-operative complications following thoracotomy, in patients who are
already cardiopulmonary compromised, create a very vulnerable situation
for the patient. The initial study consisted of six patients, five of
which were successfully managed with this new technique. The procedure
was unable to be performed in the remaining patient due to technical
difficulties. Interestingly, the Wilkins score was only implemented in
1990, 6 years following this study.44
The balloon is introduced through the saphenous vein and will ascend
into the mitral orifice. Across the mitral orifice, the balloon is
partially inflated, when fully expanded the balloon will separate the
fused commissures via expansile propulsion. Surgically, the balloon is
buoyed via a nylon micromesh and changes shape in three stages,
depending on the degree of inflation. The micromesh is essential for the
shape adaptation that the balloon experiences.44Despite medical advances, the basic premise of this technique has
remained the same. As of 2016 Adhikari and colleagues described a
similar approach.45 In selected patients, PTMV is now
the treatment of choice and is associated with less than a 1%
mortality. With any operation, the risk of embolism is always
appreciable. However, pre-operative application of transesophageal
echocardiography aids in the identification of left atrial thrombi and
therefore has limited risk of embolic stroke to 1.1% -
5.4%.46
Furthermore, a review conducted by Satya and colleagues highlighted how
PTMV resulted in an estimated doubling of the mitral valve area coupled
with a 50% decrease in the transmitral gradient. Long term follow-up
highlighted continued functional enhancement with survival rates
>80% at 10 years post-operation.47
A randomized controlled trial completed by Reyes and colleagues compared
open mitral commissurotomy to PTMV. The study focused upon sixty
patients with severe mitral stenosis, none of which were lost to follow
up. Even though long-term results were similar and both techniques
maintained a desired mitral valve area three years post-intervention,
more desirable results were achieved through PTMV (2.4 ±0.6
cm2, vs. 1.8 ±0.4 cm2). Restenosis
rates were similar in both groups and less than 40% had cardiovascular
symptoms three years post-operation. The trial emphasized the potential
complications with PTMV, but also noted superior hemodynamic results and
faster recovery due to the eradication of the need for a thoracotomy.
This led to a suggestion that those who are anatomically favorable
should undergo PTMV rather than open commissurotomy.48