title: Impact of different pacing modes on left ventricular contractility following cardiopulmonary bypass.
abstract: BACKGROUND
  Acute left ventricular (LV) dysfunction after cardiopulmonary bypass (CBP) is a serious complication in cardiac surgery. The aim of this study was to investigate the effect of different epicardial pacing modes on LV contractility and changes of myocardial oxygen extraction (MVO(2)) following CPB in an animal model. The utility of conductance catheter measurement versus left ventricular outflow tract mean systolic acceleration (LVOT(Acc)) for quantification of LV function was evaluated.
  
  
  METHODS
  Fourteen piglets underwent median sternotomy and CPB for 90 minutes, myocardial ischemia for 60 minutes, and reperfusion for 30 minutes. Different pacing modes were obtained before and after CPB to investigate changes in LV function. LV Function was quantified by end-systolic-pressure-volume relationships (ESPVR) as measured by the conductance catheter method and by LVOT(Acc) obtained from transepicardial echocardiographic studies.
  
  
  RESULTS
  LV contractility improved significantly by biventricular and atrial pacing compared with natural sinus rhythm (SR). MVO(2) remained stable or even decreased with biventricular pacing after surgery compared with SR. Right ventricular pacing resulted in poor LV-function with a rise of MVO(2). LVOT(Acc) showed a strong correlation to invasively measured ESPVR.
  
  
  CONCLUSIONS
  Postoperative biventricular pacing was associated with an improved LV contractility without rise of MVO(2) compared with SR and atrial pacing. At termination of CPB, this appears to facilitate the management of LV failure and potentially may reduce the need for inotropic support, additionally protecting myocardial metabolism. The echocardiographic assessment of LVOT(Acc) was a simple and reliable as well as effective method to quantify LV contractility and showed a good correlation with the more invasive conductance catheter.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University Hospital, Frankfurt/Main, Germany. farhad@bakhtiary.de
authors.forename: Farhad
authors.initials: F
authors.lastname: Bakhtiary
authors.forename: Selami
authors.initials: S
authors.lastname: Dogan
authors.forename: Omer
authors.initials: O
authors.lastname: Dzemali
authors.forename: Hanns
authors.initials: H
authors.lastname: Ackermann
authors.forename: Peter
authors.initials: P
authors.lastname: Kleine
authors.forename: Volker
authors.initials: V
authors.lastname: Schächinger
authors.forename: Anton
authors.initials: A
authors.lastname: Moritz
authors.forename: Tayfun
authors.initials: T
authors.lastname: Aybek
mesh_terms: D000818:Animals; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002315:Cardiopulmonary Bypass; D005260:Female; D006352:Heart Ventricles / Q000601:surgery*; D009200:Myocardial Contraction / Q000502:physiology*; D013552:Swine; D016276:Ventricular Function; D016277:Ventricular Function, Left / Q000502:physiology*