In addition, most previous studies showing a significant relationship between LV dyssynchrony and FMR assessed

regional LV dyssynchrony from only 2 segments adjacent to the anterolateral and posteromedial PMs, while the present study assessed global LV dyssynchrony from 8 segments.12),19) This may be another probable reason for the discrepancy. While the geometric parameters of the mitral apparatus were estimated by using 2D echocardiography in the past studies,18-21) we performed these measurements with combined use of 3D echocardiography and MPR mode for 3D image analysis program Inhibitors,research,lifescience,medical in the present study. Taking that accurate measurement with high reproducibility is essential for the geometric measurement of small cardiac structures such as mitral apparatus into account, it is vital to obtain the same planes that cross identical portions of a certain structure, or Inhibitors,research,lifescience,medical intersect at a specific angle in every measurement, which is not guaranteed 2D echocardiography.

For this reason, geometric measurement of the MV or the tricuspid valve was performed under MPR guide in several previous studies.7),24-26) However, it is first trial to estimate the distances of both PMs using MPR in the present study. Using conventional 2D echocardiography, the PM distance was estimated by measuring the distance between the PM head and the contralateral Inhibitors,research,lifescience,medical mitral annular point on the apical 2 or 4 chamber plane. However, this method Inhibitors,research,lifescience,medical neither guarantees the same plane crossing the identical contralateral annular

point in every measurement nor provides two distances of both PMs. In our study, we first defined the PM distance using two anatomical landmarks (the distance from MJAM to the tip of each PM head). The plane displaying the two anatomical Inhibitors,research,lifescience,medical landmarks was then obtained using MPR. We expected it would be guaranteed to acquire the identical plane displaying the same point of the PM head in every measurement under MPR guide. However, intra-observer variability of PM distance measurement in the present study was less satisfactory than we expected. It was probably due to the cone shape of the PM head. The PM head displayed and in any cut plane always had the tip PI3K Inhibitor Library concentration because of its appearance of triangle. Therefore, it was a little perplexing to identify the same tip of the PM head repeatedly even under MPR guide. However, the reproducibility is expected to improve after certain period of time of learning curve. Study limitations In the present study, first, the study population was relatively small and the MR grade leaned to the mild to moderate MR. These might affect the results of the present study. Therefore, further investigations in larger population with more diverse degrees of MR and needed. Second, we assessed LV dyssynchrony from 8 segments of LV not 12 segments of LV. Third, we estimated MR severity without accounting the loading conditions that would modulate geometry of the LV and the mitral apparatus.