Discussion
In primary MR, valve repair is the preferred treatment option (1, 2).
Valve repair has lower left ventricular heart function impairment, lower
complication rates, improved long-term outcomes, and no need for
anticoagulation (1, 2).Most mitral valve repair techniques involve
leaflet resection, suture repair, artificial chordae implantation and
restrictive band or ring annuloplasty. These surgical manoeuvres may
theoretically result in some degree of narrowing of the mitral valve
orifice (3). However, surgical repair of rheumatic mitral valve disease
is technically more demanding and has a higher potential failure rate
compared with repair of degenerative disease. But especially, in the
presence of less leaflet and subvalvular fibrosis, mitral repair can be
the initial procedure of choice in rheumatic disease (4, 5).
The development of mitral stenosis following mitral valve surgery is a
condition associated with multiple mechanisms that are poorly
understood. Currently, after mitral valve operation, functional mitral
stenosis is defined as mean transmitral pressure gradient (TMPG)
> 5 mmHg or mitral valve area (MVA) < 1.5 cm2
regardless of aetiology. (6, 7). Also, effective orifice area indexed to
body surface area (EOAi) <0.9 cm2/m2 defines severe
prosthesis-patient mismatch (PPM) after MV replacement (8). Several
factors have been associated with a higher risk for developing mitral
stenosis after MV repair, including the use of flexible Duran
annuloplasty rings versus rigid Carpentier Edwards rings, complete
annuloplasty rings versus partial bands, small versus large anterior
leaflet opening angle, and anterior leaflet tip opening length (9). In
spite of all these reasons, mainly, early functional mitral stenosis
after MV repair is thought to be a direct result of the restrictive
small annuloplasty ring, late mitral stenosis is thought to be
associated with the pannus overgrowth from the annuloplasty ring (7, 9).
Our patient’s body mass index 32.9 kg/m2, body surface
area is 2.12 m2 and when the TTE and TEE images of our
patient were examined in detail, a restrictive small complete
annuloplasty ring and mildly annular ring pannus formation were
observed. In general, larger rings are recommended in treating rheumatic
mitral disease, for example, 31 to 32 mm in men and 29 to 31 mm in
women. If the body surface area is large, the larger annular ring should
be implanted (10).
Like our patient, active obese individuals and high cardiac output state
(anaemia, obesity, thyrotoxicosis) may cause an increase in the mitral
pressure gradient. In such patients, the defect in the surgical
technique and the application of restrictive small annuloplasty causes
an increased gradient, leading to the development of severe functional
mitral stenosis, especially when accompanied by a slight increase in
pannus tissue. In rheumatic mitral valve patients, repair surgery is
more difficult and the results are worse than degenerative mitral valve
repair surgery. So, the surgical technique, the diameter and structure
of the annular ring to be used are very important.