Ventricular remodeling after cardiomyoplasty in heart failure sheep: passive and dynamic effects

Abstract Background . Recent reports claim that cardiomyoplasty (CMP) has a girdling effect on the left ventricle, to prevent dilatation and functional deterioration, but the mechanism of its long-term effects on the native heart is not known. We compared the relative role of CMP's active squeezing and passive girdling in chronically failing hearts. Methods . After induction of stable heart failure (left ventricular ejection fraction=27% ± 7%) by staged coronary microembolization, CMP was performed in 11 of 18 sheep. After 8 weeks pacing training of the latissimus dorsi muscle (LDM), cardiac assist was begun with 1:2 synchronous bursts in 6 sheep (d-CMP, n=6), and the LDM in the passive group (p-CMP, n=5) remained unstimulated. Four (base line) and 30 weeks after induction of heart failure, the pressure-volume relationship was derived. Results . After 30 weeks in d-CMP the slope (E max ) of the end-systolic pressure-volume relationship increased by 66% ± 55% ( p p p p > 0.05) and an increase (18% ± 15%, p Conclusions . Dynamic CMP improved native heart's contractility and external work efficiency. In addition, whereas passive CMP has simply a girdling effect, dynamic CMP also induces reverse left ventricular chamber remodeling.