title: Heart failure and movement-induced hemodynamics: partitioning the impact of central and peripheral dysfunction.
abstract: BACKGROUND
  The complex pathophysiology of heart failure (HF) creates a challenging paradigm to differentiate the role of central and peripheral hemodynamic dysfunction during conventional exercise. Adopting a novel reductionist approach with potential clinical relevance, we studied the central and peripheral contributors to both continuous and single passive leg movement (PLM)-induced hyperemia in 14 HF patients with reduced ejection fraction (HFrEF) and 13 controls.
  
  
  METHODS
  Heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), and femoral artery blood flow (FBF) were recorded during PLM.
  
  
  RESULTS
  The FBF response (area under the curve; AUC) to 60s of continuous PLM was attenuated in the HFrEF (25±15ml AUC) compared to controls (199±34ml AUC) as were peak changes from baseline for FBF, leg vascular conductance (LVC), CO, and HR. During single PLM, increases in CO and HR were smaller and no longer different between groups, supporting the use of this modality to assess groups with disparate central hemodynamics. Interestingly, single PLM-induced hyperemia, likely predominantly driven by flow-mediated vasodilation due to minimal vessel deformation, was essentially nonexistent in the HFrEF (-9±10ml AUC) in contrast to the controls (43±25ml AUC).
  
  
  CONCLUSIONS
  These data fail to support a HFrEF-associated exaggeration in the mechanoreceptor driven component of the exercise pressor response. In fact, by exhibiting limited central hemodynamic responses compared to the controls, the observed attenuation in movement-induced FBF in HFrEF appears largely due to peripheral vascular dysfunction, particularly flow-mediated vasodilation.
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT, United States; Department of Internal Medicine, Division of Geriatrics, University of Utah School of Medicine, Salt Lake City, UT, United States. Electronic address: melissa.witman@utah.edu.
authors.forename: Melissa A H
authors.initials: MA
authors.lastname: Witman
authors.affiliation: Department of Health and Exercise Sciences, Skidmore College, Saratoga Springs, NY, United States.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ives
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT, United States; Department of Internal Medicine, Division of Geriatrics, University of Utah School of Medicine, Salt Lake City, UT, United States.
authors.forename: Joel D
authors.initials: JD
authors.lastname: Trinity
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT, United States; Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, United States.
authors.forename: H Jonathan
authors.initials: HJ
authors.lastname: Groot
authors.affiliation: Department of Internal Medicine, Division of Cardiology, George E. Whalen VA Medical Center, University of Utah Medical Center, University of Utah School of Medicine, Salt Lake City, UT, United States.
authors.forename: Josef
authors.initials: J
authors.lastname: Stehlik
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT, United States; Department of Internal Medicine, Division of Geriatrics, University of Utah School of Medicine, Salt Lake City, UT, United States; Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, United States.
authors.forename: Russell S
authors.initials: RS
authors.lastname: Richardson
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015915:Motion Therapy, Continuous Passive / Q000379:methods*; D009068:Movement / Q000502:physiology*; D016491:Peripheral Vascular Diseases / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy
keywords: Afferents; Blood flow; Exercise pressor response; Mechanoreflex; Passive exercise