title: Evaluation of acute dual-chamber pacing with a range of atrioventricular delays on cardiac performance in refractory heart failure.
abstract: OBJECTIVE
  This study evaluated how variations in atrioventricular (AV) delay affect hemodynamic function in patients with refractory heart failure being supported with intravenous inotropic and intravenous or oral inodilating agents.
  
  
  BACKGROUND
  Although preliminary data have suggested that dual-chamber pacing with short AV delays may improve cardiac function in patients with heart failure, detailed Doppler and invasive hemodynamic assessment of patients with refractory New York Heart Association class IV heart failure has not been performed.
  
  
  METHODS
  Nine patients with functional class IV clinical heart failure had Doppler assessment of transvalvular flow and right heart catheterization performed during pacing at AV delays of 200, 150, 100 and 50 to 75 ms.
  
  
  RESULTS
  Systemic arterial, pulmonary artery, right atrial and pulmonary capillary wedge pressures, cardiac index, systemic and pulmonary vascular resistances, stroke volume index, left ventricular stroke work index (SWI) and arteriovenous oxygen content difference demonstrated no significant changes during dual-chamber pacing with AV delays of 200 to 50 to 75 ms. There were also no changes in the Doppler echocardiographic indexes of systolic or diastolic ventricular function. The study was designed with SWI as the outcome variable. Assuming a clinically significant change in the SWI of 5 g/min per m2, a type I error of 0.05 and the observed standard deviation from our study, the observed power of our study is 85% (type II error of 15%).
  
  
  CONCLUSIONS
  Changes in AV delay between 200 and 50 ms during dual-chamber pacing do not significantly affect acute central hemodynamic data, including cardiac output and systolic or diastolic ventricular function in patients with severe refractory heart failure due to dilated cardiomyopathy.
authors.affiliation: Department of Medicine, University of California San Francisco, 94143, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Shinbane
authors.forename: E
authors.initials: E
authors.lastname: Chu
authors.forename: T
authors.initials: T
authors.lastname: DeMarco
authors.forename: Y
authors.initials: Y
authors.lastname: Sobol
authors.forename: A P
authors.initials: AP
authors.lastname: Fitzpatrick
authors.forename: D M
authors.initials: DM
authors.lastname: Lau
authors.forename: C
authors.initials: C
authors.lastname: Klinski
authors.forename: N B
authors.initials: NB
authors.lastname: Schiller
authors.forename: J C
authors.initials: JC
authors.lastname: Griffin
authors.forename: K
authors.initials: K
authors.lastname: Chatterjee
mesh_terms: D000368:Aged; D006328:Cardiac Catheterization; D002304:Cardiac Pacing, Artificial; D002311:Cardiomyopathy, Dilated / Q000150:complications; D015150:Echocardiography, Doppler; D005069:Evaluation Studies as Topic; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged