Undersized mitral annuloplasty inhibits left ventricular basal wall thickening but does not affect equatorial wall cardiac strains.
OBJECTIVE
Undersized mitral annuloplasty has been widely employed for patients with ischemic mitral regurgitation. Beyond correction of mitral regurgitation, ring annuloplasty is postulated to normalize global left ventricular (LV) shape, thereby decreasing LV wall stress and promoting reverse LV remodeling. The effect of undersized annuloplasty on regional transmural LV wall thickening and strain patterns, however, has not been examined.


METHODS
In nine sheep, transmural radiopaque beadsets were inserted into the anterobasal and equatorial lateral LV walls, with additional markers silhouetting the left ventricle and mitral annulus. Four-dimensional marker dynamics were studied with biplane videofluoroscopy (open-chest) before and after tightening a Paneth-type mitral annuloplasty suture. LV volumes, mitral dimensions, transmural circumferential, longitudinal, and radial systolic strains, and end-diastolic (ED) and end-systolic (ES) remodeling strains in the two LV regions were computed.


RESULTS
In the anterobasal LV wall close to the mitral annulus, annuloplasty increased ED wall thickness and surprisingly reduced systolic radial strain (wall thickening) at all transmural depths. Radial subepicardial, midwall, and subendocardial wall-thickening strains at ES in the anterobasal LV site were 0.25 +/- 0.15, 0.33 +/- 0.16, and 0.47 +/- 0.29, respectively, before tightening the suture annuloplasty, compared to 0.13 +/- 0.12, 0.15 +/- 0.18, and 0.20 +/- 0.26 after tightening. In the equatorial lateral LV wall further away from the annulus, most LV transmural systolic and remodeling strains did not change.


CONCLUSIONS
Simulated undersized annuloplasty acutely decreased transmural systolic LV wall thickening in the anterobasal region, without substantially affecting transmural deformations in the lateral LV wall. These acute effects of undersized annuloplasty require a better understanding as they may potentially be deleterious, and a direct ventricular approach may be needed as an adjunct to promote reverse LV remodeling.
Cheng
Allen
A
Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Stanford, California 94305-5247, USA.
Nguyen
Tom C
TC
Malinowski
Marcin
M
Liang
David
D
Daughters
George T
GT
Ingels
Neil B
NB
Miller
D Craig
DC
D000818:Animals; D001696:Biomechanical Phenomena; D003287:Contrast Media; D003971:Diastole / Q000502:physiology; D005471:Fluoroscopy; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D008297:Male; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D012756:Sheep; D013599:Systole / Q000502:physiology; D017725:Ventricular Pressure / Q000502:physiology; D020257:Ventricular Remodeling / Q000502:physiology*
D003287:Contrast Media