title: Dysfunction induced by ischemia versus edema: does edema matter?
abstract: OBJECTIVE
  Recovery from pediatric cardiac surgery is affected by ischemia-reperfusion injury, cardiac edema, and in some cases a low cardiac output syndrome. Although association has been made between the development of edema and dysfunction, modeling is confounded by intercurrent injurious stimuli that also cause cardiac edema and dysfunction. We tested whether a true causal relationship exists between edema and cardiac dysfunction.
  
  
  METHODS
  We induced either ischemia or edema alone in isolated cardiomyocytes and whole Langendorff-perfused hearts. Function was measured as shortening dynamics and developed pressure, respectively.
  
  
  RESULTS
  Ischemic injury impaired function in both cardiomyocytes and whole hearts. Isolated cells showed significant reduction in peak shortening and departure and relaxation velocities. Whole hearts displayed severely reduced developed pressures. Hyposmotic solution forced cardiomyocytes to swell to 7% greater than their normal size. No significant effect on shortening was seen. Similarly, Langendorff-perfused hearts were induced to take on 3% more water than control-perfused hearts and 9% more water than nonperfused hearts. This additional water was associated with mild dysfunction.
  
  
  CONCLUSIONS
  We demonstrate the capacity of the heart to tolerate edema greater than that seen in clinical settings without residual effect. Ischemia results in ongoing contractile dysfunction of both isolated cardiomyocytes and whole hearts. We conclude that dysfunction resulting from edema in ex vivo cardiac models is mild and suggest review of the importance given to edema-mediated dysfunction after cardiac surgery.
authors: Kids Heart Research, The Children's Hospital at Westmead, Sydney, Australia.
authors: Tanya L
authors: TL
authors: Butler
authors: Jonathan R
authors: JR
authors: Egan
authors: Fabian G
authors: FG
authors: Graf
authors: Carol G
authors: CG
authors: Au
authors: Aisling C
authors: AC
authors: McMahon
authors: Kathryn N
authors: KN
authors: North
authors: David S
authors: DS
authors: Winlaw
mesh_terms: D000818:Animals; D004489:Edema, Cardiac / Q000150:complications / Q000503:physiopathology*; D006321:Heart / Q000503:physiopathology*; D066298:In Vitro Techniques; D009200:Myocardial Contraction; D015428:Myocardial Reperfusion Injury / Q000150:complications / Q000503:physiopathology*; D032383:Myocytes, Cardiac / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017725:Ventricular Pressure