Determination of Inoue Balloon Size by Analysis of Mitral Valve Geometry using Three-Dimensional Transesophageal Echocardiography in Patients with Mitral Stenosis

Abstract

Background: Percutaneous mitral balloon commissurotomy (PMBC) is recommended as an initial treatment in patients with mitral stenosis (MS) and favorable valve morphology. Determining the appropriate balloon inflation size is a critical step in this percutaneous procedure. We aimed to evaluate the clinical value of balloon size selection based on the quantitative analysis of mitral valve (MV) geometry determined by 3D transesophageal echocardiography (TEE).

Methods: A total of 184 consecutive patients who underwent PMBC for significant MS were retrospectively analyzed. MV annulus geometry was analyzed during mid-diastole, including lateral-medial diameters obtained from dedicated 3D software (LMD-3d) or from analysis using multiplanar reconstruction image (LMD-mpr). Patients were categorized into three groups based on the PMBC results; those with successful results as Group SU, those with remnant mitral stenosis as Group MS, and those with significant MR as Group MR.

Results: Group SU, MS, and MR consisted of 110, 50 and 17 patients, respectively. We compared three conventional formulas (Formula 1,2,3) for determining balloon size based on the patient’s height or body surface area with two new formulas derived from mitral valve geometry using linear regression analysis in Group SU: balloon size = 0.0684 × LMD-3d + 24.309 (Formula 4) and 0.061 × LMD-mpr + 24.573 (Formula 5). Compared with the calculated balloon using formula 4, the inflated balloon sizes used in Group MS were significantly smaller (-0.78±1.02; p<0.001), while those used in Group MR were significantly larger (0.56±1.05; p=0.04). This pattern was consistent in formula 5 as well.

Conclusions: Selecting the Inoue balloon inflation size based on the mitral annulus diameter determined by 3D TEE might be a reasonable approach. Further prospective study is warranted to validate the clinical benefit of the formulas derived from this study.

Key word: mitral stenosis, percutaneous mitral balloon commissurotomy, transesophageal echocardiography