Isolated annular dilation does not usually cause important functional mitral regurgitation Comparison between patients with lone atrial fibrillation and those with idiopathic or ischemic cardiomyopathy

AbstractObjectivesWe sought to test whether isolated mitral annular (MA) dilation can cause important functional mitral regurgitation (MR).BackgroundMitral annular dilation has been considered a primary cause of functional MR. Patients with functional MR, however, usually have both MA dilation and left ventricular (LV) dilation and dysfunction. Lone atrial fibrillation (AF) can potentially cause isolated MA dilation, offering a unique opportunity to relate MA dilation to leaflet function.MethodsMid-systolic MA area, MR fraction, LV volumes and papillary muscle (PM) leaflet tethering length were compared by echocardiography among 18 control subjects, 25 patients with lone AF and 24 patients with idiopathic or ischemic cardiomyopathy (ICM).ResultsPatients with lone AF had a normal LV size and function, but MA dilation (isolated MA dilation) significant and comparable to that of patients with ICM (MA area: 8.0 ± 1.2 vs. 11.6 ± 2.3 vs. 12.5 ± 2.9 cm2[control vs. lone AF vs. ICM]; p < 0.001 for both lone AF and ICM). However, patients with lone AF had only modest MR, compared with that of patients with ICM (MR fraction: −3 ± 8% vs. 3 ± 9% vs. 36 ± 25%; p < 0.001 for patients with ICM). Multivariate analysis identified PM tethering length, not MA dilation, as an independent primary contributor to MR.ConclusionsIsolated annular dilation does not usually cause moderate or severe MR. Important functional MR also depends on LV dilation and dysfunction, leading to an altered force balance on the leaflets, which impairs coaptation

Papillary Muscle Dysfunction Attenuates Ischemic Mitral Regurgitation in Patients With Localized Basal Inferior Left Ventricular Remodeling Insights From Tissue Doppler Strain Imaging

ObjectivesThe purpose of this research was to test whether papillary muscle (PM) dysfunction attenuates ischemic mitral regurgitation (MR) in patients with left ventricular (LV) remodeling of a similar location and extent.BackgroundPapillary muscle dysfunction could attenuate tethering and MR because of PM elongation. However, variability in the associated LV remodeling, which exaggerates tethering, can influence the relationship between PM dysfunction and MR.MethodsIn 40 patients with a previous inferior myocardial infarction but without other lesions, the LV volume, sphericity, PM tethering distance, PM longitudinal systolic strain, and MR fraction were quantified by echocardiography. The patients were divided into two groups: group 1 with significant basal inferoposterior LV bulging but without advanced LV bulging involving other territories, therefore with a similar location and extent of LV remodeling, and group 2 without significant LV bulging.ResultsThe medial PM tethering distance was significantly correlated with the %MR fraction (r2= 0.64, p < 0.01), and multiple regression analysis identified an increase in the tethering distance as the only independent determinant of the MR fraction in all subjects and also in group 1. The PM longitudinal systolic strain had no significant relationships with MR fraction in all subjects with variable degrees of LV remodeling, but it had a significant inverse correlation with the MR fraction (r2= 0.33, p < 0.01) in group 1 with LV remodeling of a similar location and extent, indicating that PM dysfunction is associated with less MR.ConclusionsPapillary muscle dysfunction, reducing its longitudinal contraction to induce leaflet tethering, attenuates ischemic MR in patients with basal inferior LV remodeling

Isospin identification for A = 25A=25 mirror nuclei by high resolution (p,p′)(p,p′) and (3He,t)(3He,t) experiments

Gamow-Teller and M1M1 states excited in 25Mg(3He,t)25Al25Mg(3He,t)25Al and 25Mg(p,p′)25Mg(p,p′) reactions at 0° and 450 MeV incident energy, respectively, have been measured and compared. Good symmetry structure in the mirror nuclei 25Al25Al and 25Mg25Mg has been identified up to the highest measured excitation energy of Ex ∼ 16 MeV.Ex∼16MeV. © 2001 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87741/2/886_2.pd