Passive ventricular constraint amends the course of heart failure: a studyin an ovine model of dilated cardiomyopathy

Objective: Dilated cardiomyopathy (DCM) is associated with a progressive de terioration in cardiac function. We hypothesised that some of the deleterio us effects of DCM could be reduced by mechanically limiting the degree of c ardiac 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 day s at a rate which resulted in an initial 10% decrease in CO (to a maximum o f 190 bpm). A custom polyester jacket (Acorn Cardiovascular, St Paul, MN) w as then placed, via a partial lower sternotomy, on the ventricular epicardi um 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 echocardiograph ic parameters were determined at baseline, implant and at termination. Resu lts: At termination, the left ventricular fractional shortening was signifi cantly higher (p=0.03), the degree of mitral valve regurgitation lower (sca led 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 det erioration in cardiac function associated with progressive dilated cardiomy opathy. These results suggest that maintainance of a more normal cardiac si ze and shape may be beneficial in patients with dilated cardiomyopathy. (C) 1999 Elsevier Science B.V. All rights reserved.