Mechanism of ischemic mitral regurgitation with segmental left ventricular dysfunction: three-dimensional echocardiographic studies in models of acute and chronic progressive regurgitation
Yutaka Otsuji, MD, FACCa,
Mark D. Handschumacher, BSa,
Noah Liel-Cohen, MDa,
Hiroaki Tanabe, MDa,
Leng Jiang, MD, FACCa,
Ehud Schwammenthal, MD, PhDa,
J. Luis Guerrero, BSa,
Lori A. Nicholls, BSa,
Gus J. Vlahakes, MD, FACCa and
Robert A. Levine, MD, FACCa
a Cardiac Ultrasound Laboratory and Cardiovascular Surgical Unit, Massachusetts General Hospital, Departments of Medicine and Surgery, Harvard Medical School, Boston, Massachusetts, USA
View larger version (59K):
[in a new window]
|
Figure 1 Three-dimensional (3D) analysis of the mitral apparatus: (A) Reconstruction of intersecting images. (B) Points traced to identify papillary muscle (PM) tip (yellow square), mitral annulus (blue with arrows), aortic annulus (pink). (C,D)Display of traced 3D points, with mitral and aortic annuli as blue and pink, PM tips as yellow (lateral) and green (medial) and medial junction of the annuli (medial trigone) as red. (E) Spatial relations in reconstructed mitral apparatus. The mitral annular least-squares plane is shown in light gray, with mitral and aortic annular centroids in white and blue. (F)View of the same diagram looking directly onto the mitral annulus from the apex, with PM tips as yellow and green balls, aortic annulus in brown and medial trigone in red. Arrows indicate tethering distances between PM tips and medial trigone on the anterior mitral annulus. Ao = aorta; LA = left atrium; LV = left ventricle.
|
|
View larger version (89K):
[in a new window]
|
Figure 2 Upper panels: Apical two-dimensional echo images (LV on top, LA below the mitral valve, aorta at lower right) showing no mitral regurgitation (MR) at baseline (S1) and with left circumflex coronary artery (LCX) occlusion but pericardial restraint (S2) and moderate MR with the pericardium open (S3). Lower panels: Views of the 3D reconstructions from the apex, with the mitral annulus en face, the PM tips as yellow and green and the anterior annular reference point as red (Fig. 1F). With LCX ligation, the PMs, especially the ischemic medial one (green), migrate away from the annular reference, stretching the leaflets over a larger distance. This shift is mild with limited LV dilation (S1 to S2) and larger when geometric changes are permitted (S3, open pericardium). Other abbreviations as in Figure 1.
|
|
View larger version (16K):
[in a new window]
|
Figure 3 Correlation between the tethering distance and mitral regurgitation orifice area.
|
|
View larger version (75K):
[in a new window]
|
Figure 4 Upper panels: Two-dimensional echo apical four-chamber images in the sheep, with no MR at baseline (left), trace MR acutely after coronary ligation (middle) and apical leaflet tenting with moderate MR in the chronic phase eight weeks later with prominent LV remodeling (right). Lower panels: Views of the 3D reconstructions from the apex (Fig. 1F). With LCX obtuse marginal branches 2 and 3 ligation, the PMs, especially the ischemic medial one (green), migrate away from the annular reference (red), stretching the leaflets over a larger distance. This shift is mild in the acute stage, without LV remodeling, and larger in the chronic stage after remodeling. Other abbreviations as in Figure 1.
|
|
|
