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.