The effect of pure mitral regurgitation on mitral annular geometry and three-dimensional saddle shape.
OBJECTIVE
Chronic ischemic mitral regurgitation is associated with mitral annular dilatation in the septal-lateral dimension and flattening of the annular 3-dimensional saddle shape. To examine whether these perturbations are caused by the ischemic insult, mitral regurgitation, or both, we investigated the effects of pure mitral regurgitation (low pressure volume overload) on annular geometry and shape.


METHODS
Eight radiopaque markers were sutured evenly around the mitral annulus in sheep randomized to control (CTRL, n = 8) or experimental (HOLE, n = 12) groups. In HOLE, a 3.5- to 4.8-mm hole was punched in the posterior leaflet to generate pure mitral regurgitation. Four-dimensional marker coordinates were obtained radiographically 1 and 12 weeks postoperatively. Mitral annular area, annular septal-lateral and commissure-commissure dimensions, and annular height were calculated every 16.7 ms.


RESULTS
Mitral regurgitation grade was 0.4 +/- 0.4 in CTRL and 3.0 +/- 0.8 in HOLE (P < .001) at 12 weeks. End-diastolic left ventricular volume index was greater in HOLE at both 1 and 12 weeks; end-systolic volume index was larger in HOLE at 12 weeks. Mitral annular area increased in HOLE predominantly in the commissure-commissure dimension, with no difference in annular height between HOLE versus CTRL at 1 or 12 weeks, respectively.


CONCLUSIONS
In contrast with annular septal-lateral dilatation and flattening of the annular saddle shape observed with chronic ischemic mitral regurgitation, pure mitral regurgitation was associated with commissure-commissure dimension annular dilatation and no change in annular shape. Thus, infarction is a more important determinant of septal-lateral dilatation and annular shape than mitral regurgitation, which reinforces the need for disease-specific designs of annuloplasty rings.
Nguyen
Tom C
TC
Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California 94305-5247, USA.
Itoh
Akinobu
A
Carlhäll
Carl J
CJ
Bothe
Wolfgang
W
Timek
Tomasz A
TA
Ennis
Daniel B
DB
Oakes
Robert A
RA
Liang
David
D
Daughters
George T
GT
Ingels
Neil B
NB
Miller
D Craig
DC
D000818:Animals; D002908:Chronic Disease; D004108:Dilatation, Pathologic; D005471:Fluoroscopy; D008943:Mitral Valve / Q000473:pathology*; D008944:Mitral Valve Insufficiency / Q000473:pathology*; D012756:Sheep; D013525:Surgical Instruments; D014741:Video Recording