Early postinfarction ventricular restraint improves borderzone wall thickening dynamics during remodeling.
BACKGROUND
Early infarct expansion impairs function of normally perfused borderzone myocardium (BZM), initiates adverse remodeling, and portends a poor long-term outcome. Early ventricular restraint has been demonstrated to improve global remodeling but its effect on BZM function has not been assessed. Using an ovine model of infarct induced remodeling and MRI, we tested the hypothesis that ventricular restraint early after MI preserves BZM function and reduces remodeling.


METHODS
Six sheep had a large anterior infarction after ligation of all diagonal branches. One week after infarction 3 sheep had placement of a cardiac support device (CSD) to restrain infarct expansion. Global remodeling and borderzone wall thickening strain were assessed using tagged MRI before and 8 weeks after infarction.


RESULTS
Global remodeling was greatly reduced in the CSD group compared with control. The BZM systolic wall thickening was similar in both groups at baseline (13.5% +/- 2.0%, control; 12.8% +/- 2.0%, CSD, p = 0.8). After 8 weeks of infarction-induced remodeling, systolic wall thickening strain decreased significantly to 4.9% +/- 0.7% in the control group (p = 0.03). In contrast, systolic wall thickening was preserved in the CSD group at 8 weeks (11.0% +/- 1.6%, p = 0.3). In the control group all thickening occurred during isovolemic contraction, plateauing during ejection. The CSD improved late systolic borderzone wall thickening, although dynamics remained perturbed.


CONCLUSIONS
Ventricular restraint early after MI improves both contractile function of the BZM and global ventricular remodeling. The dynamics of BZM wall thickening are impaired during remodeling. The CSD significantly improves but does not completely maintain baseline BZM wall thickening dynamics.
Pilla
James J
JJ
Harrison Department of Surgical Research, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-4283, USA.
Blom
Aaron S
AS
Gorman
Joseph H
JH
Brockman
Daniel J
DJ
Affuso
John
J
Parish
Landi M
LM
Sakamoto
Hiroaki
H
Jackson
Benjamin M
BM
Acker
Michael A
MA
Gorman
Robert C
RC
D000818:Animals; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology* / Q000503:physiopathology*; D012756:Sheep; D013997:Time Factors; D020257:Ventricular Remodeling