title: Functional recovery of the native heart after cardiomyoplasty in sheep with heart failure: passive and dynamic effects of volume loading.
abstract: 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.
authors.affiliation: Cardiac Technology Centre, Department of Cardiology, Royal North Shore Hospital, Sydney, New South Wales, Australia. stephenh@med.usyd.edu.au
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Shirota
authors.forename: Yifei
authors.initials: Y
authors.lastname: Huang
authors.forename: Osamu
authors.initials: O
authors.lastname: Kawaguchi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yuasa
authors.forename: Peter W
authors.initials: PW
authors.lastname: Brady
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ueda
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Hunyor
mesh_terms: 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