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DOI: 10.1055/s-2006-925735
Three-dimensional assessment of left ventricular geometry and annular dilatation provides new mechanistic insights into the surgical correction of ischemic mitral regurgitation
Objectives: Recently, annulus distortion has been proposed as the major determinant of ischemic mitral regurgitation (IMR) and accordingly new asymmetrical annuloplasty rings have been developed. In a previous study we observed that annulus enlargement uniformly affects the different annular regions. Aim of this study was to investigate the relationship between LV geometry, annular shape and the amount of mitral regurgitation in patients with IMR (group 1, n=30) compared to patients with MR due to primary valvular lesions (group 2, n=30).
Methods: Annular geometry was evaluated by diameters, areas and their percentual shortening. LV geometry were assessed by the “Sphericity Index“ as LV volume divided by the volume of a sphere with diameter equal to the longest axis (Hung et al, Circulation 2004). Eight annular regions and the degree of MR was assessed by jet volumes (De Simone et al, Ann Thorac Surg 1999) by 3D-Echocardiography.
Results: Annular diameters and areas were significantly larger in group 1 than group 2 (Table 1). No asymmetric annular enlargement in the P3 region was observed. Annular enlargement correlated to the degree of MR in group 1 but not in group 2. Sphericity Index was larger in group 1 than in group 2.
|
Parameters |
Group 1 (n=30) with IMR |
Group 2 (n=30) primary valvular lesions |
|
Longitudinal Diameter (mm) |
54.3±3.1 |
40.9±2.6# |
|
Antero-lateral Diameter (mm) |
32.2±3.3 |
27.1±2.9# |
|
Systolic Annular Area (mm2) |
889.2±54.8 |
556.4±36.2# |
|
Annular Area Change (%) |
10.3±1.1 |
21.9±1.6# |
|
Diastolic Annular Area (mm2) |
993.3±66.6 |
702.1±47.9# |
|
Regurgitant Jet Volume (cm3) |
22.2±13.2 |
32.8±14.4# |
|
Sphericity Index |
0.52±0.11 |
0.33±0.09# |
|
#: p<0.01 vs. group 1 |
||
Conclusion: These findings suggest that ring annuloplasty as sole therapy for IMR may once again deceive the current initial enthusiasm for asymmetric rings, since it reduces tethering only at the annular and not at the ventricular level. Accurate individual 3D assessment of underlying mechanisms may improve the surgical outcome of IMR.