Blunted frequency-dependent upregulation of cardiac output is related to impaired relaxation in diastolic heart failure.
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.
Wachter
Rolf
R
Department of Cardiology and Pneumology, University of Göttingen, Göttingen, Germany.
Schmidt-Schweda
Stephan
S
Westermann
Dirk
D
Post
Heiner
H
Edelmann
Frank
F
Kasner
Mario
M
Lüers
Claus
C
Steendijk
Paul
P
Hasenfuss
Gerd
G
Tschöpe
Carsten
C
Pieske
Burkert
B
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