Functional recovery of the native heart after cardiomyoplasty in sheep with heart failure: passive and dynamic effects of volume loading.
BACKGROUND
Dynamic cardiomyoplasty (d-CMP) encourages reverse remodeling and improved contractility and stroke work (SW) efficiency of the failing native heart. This contrasts with passive cardiomyoplasty (p-CMP), which provides "passive girdling." To further evaluate pump recovery we assessed native left ventricular performance (without assist) 6 months after dynamic and passive CMP in sheep with heart failure with acute volume loading.


METHODS
Heart failure (left ventricular ejection fraction 26%+/-8%) induced by coronary microembolization was followed by CMP in 11 sheep. After 8 weeks of muscle "training," paced cardiac assist was undertaken in the d-CMP group (n = 6). Five sheep with heart failure served as controls. Six months later the pressure-volume relationship was derived before and after volume loading by colloid solution. Latissimus dorsi muscle pacing was previously ceased in the d-CMP group.


RESULTS
Volume loading increased left ventricular end-diastolic volume and pressure in all groups. After volume loading in d-CMP, the SW and pressure-volume area were increased, and SW efficiency remained unchanged. In p-CMP neither variable changed, whereas in control heart failure SW efficiency decreased due to a rise in pressure-volume area with stable SW.


CONCLUSIONS
Based on response to volume loading, the failing native heart after 6 months of d-CMP showed functional recovery from "active girdling," whereas p-CMP prevented functional deterioration through passive girdling. The failing control heart progressively deteriorated.
Shirota
Kazuaki
K
Cardiac Technology Centre, Department of Cardiology, Royal North Shore Hospital, Sydney, New South Wales, Australia. stephenh@med.usyd.edu.au
Huang
Yifei
Y
Kawaguchi
Osamu
O
Yuasa
Takeshi
T
Brady
Peter W
PW
Ueda
Yuichi
Y
Hunyor
Stephen N
SN
D000818:Animals; D018421:Cardiomyoplasty; D006333:Heart Failure / Q000503:physiopathology / Q000601:surgery*; D006439:Hemodynamics; D012756:Sheep; D013318:Stroke Volume; D016277:Ventricular Function, Left; D017725:Ventricular Pressure