title: Blunted frequency-dependent upregulation of cardiac output is related to impaired relaxation in diastolic heart failure.
abstract: OBJECTIVE
  We tested the hypothesis that, in heart failure with normal ejection fraction (HFNEF), diastolic dysfunction is accentuated at increasing heart rates, and this contributes to impaired frequency-dependent augmentation of cardiac output.
  
  
  RESULTS
  In 17 patients with HFNEF (median age 69 years, 13 female) and seven age-matched control patients, systolic and diastolic function was analysed by pressure-volume loops at baseline heart rate and during atrial pacing to 100 and 120 min(-1). At baseline, relaxation was prolonged and end-diastolic left ventricular stiffness was higher in HFNEF, whereas all parameters of systolic function were not different from control patients. This resulted in smaller end-diastolic volumes, higher end-diastolic pressure, and a lower stroke volume and cardiac index in HFNEF vs. control patients. During pacing, frequency-dependent upregulation of contractility indices (+dP/dt(max) and Ees) occurred similarly in HFNEF and control patients, but frequency-dependent acceleration of relaxation (dP/dt(min)) was blunted in HFNEF. In HFNEF, end-diastolic volume and stroke volume decreased with higher heart rates while both remained unchanged in control patients.
  
  
  CONCLUSIONS
  In HFNEF, frequency-dependent upregulation of cardiac output is blunted. This results from progressive volume unloading of the left ventricle due to limited relaxation reserve in combination with increased LV passive stiffness, despite preserved force-frequency relation.
authors.affiliation: Department of Cardiology and Pneumology, University of Göttingen, Göttingen, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Wachter
authors.forename: Stephan
authors.initials: S
authors.lastname: Schmidt-Schweda
authors.forename: Dirk
authors.initials: D
authors.lastname: Westermann
authors.forename: Heiner
authors.initials: H
authors.lastname: Post
authors.forename: Frank
authors.initials: F
authors.lastname: Edelmann
authors.forename: Mario
authors.initials: M
authors.lastname: Kasner
authors.forename: Claus
authors.initials: C
authors.lastname: Lüers
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Gerd
authors.initials: G
authors.lastname: Hasenfuss
authors.forename: Carsten
authors.initials: C
authors.lastname: Tschöpe
authors.forename: Burkert
authors.initials: B
authors.lastname: Pieske
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D002304:Cardiac Pacing, Artificial; D016022:Case-Control Studies; D004452:Echocardiography; D005260:Female; D054144:Heart Failure, Diastolic / Q000503:physiopathology* / Q000628:therapy; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology; D015854:Up-Regulation