Passive ventricular constraint amends the course of heart failure: a study in an ovine model of dilated cardiomyopathy.
OBJECTIVE
Dilated cardiomyopathy (DCM) is associated with a progressive deterioration in cardiac function. We hypothesised that some of the deleterious effects of DCM could be reduced by mechanically limiting the degree of cardiac dilatation.


METHODS
A Transonic 20A cardiac output (CO) flow-probe was implanted in the pulmonary artery of 12 adult (52 +/- 4 kg) sheep. Early heart failure was created by rapid right ventricular (RV) pacing for 21 days at a rate which resulted in an initial 10% decrease in CO (to a maximum of 190 bpm). A custom polyester jacket (Acorn Cardiovascular, St Paul, MN) was then placed, via a partial lower sternotomy, on the ventricular epicardium of all sheep. Animals were randomised either to jacket retention (wrap) or removal (sham). Pacing was recommenced at a higher rate (that initiated a further 10% decrease in CO) for 28 days. Haemodynamic and echocardiographic parameters were determined at baseline, implant and at termination.


RESULTS
At termination, the left ventricular fractional shortening was significantly higher (p = 0.03), the degree of mitral valve regurgitation lower (scaled 0-3) (p = 0.03) and the left ventricular long axis area smaller (p = 0.02) in the wrap animals compared with sham.


CONCLUSIONS
In this model of heart failure, ventricular constraint with a polyester jacket diminished the deterioration in cardiac function associated with progressive dilated cardiomyopathy. These results suggest that maintainance of a more normal cardiac size and shape may be beneficial in patients with dilated cardiomyopathy.
Power
J M
JM
Department of Medicine, University of Melbourne, Australia. jmp@austin.unimelb.edu.au
Raman
J
J
Dornom
A
A
Farish
S J
SJ
Burrell
L M
LM
Tonkin
A M
AM
Buxton
B
B
Alferness
C A
CA
D000818:Animals; D002304:Cardiac Pacing, Artificial; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D004452:Echocardiography; D006321:Heart / Q000503:physiopathology; D010496:Pericardium; D012756:Sheep; D020257:Ventricular Remodeling