title: The effects of acute normovolemic hemodilution on left ventricular systolic and diastolic function in the absence or presence of beta-adrenergic blockade in dogs.
abstract: Acute normovolemic hemodilution (ANH) increases cardiac output because of a reduction in blood viscosity and enhancement of left ventricular (LV) contractility. The status of LV function, especially LV diastolic function during ANH, remains controversial. We therefore examined LV systolic and diastolic function during ANH. Sixteen dogs were anesthetized with isoflurane in the absence (Group 1) and presence (Group 2) of beta-adrenergic blockade (propranolol 1 mg/kg). LV contractility was quantified by the slope (M(w)) of the stroke work and end-diastolic volume relation. Diastolic function was evaluated with the time constant of LV relaxation (T), chamber stiffness constant (K(c)), peak LV diastolic filling rate during early filling (peak E) and atrial contraction (peak A), and ratio of peak E to peak A (E/A). Normovolemic exchange of blood (50 mL/kg) for 6% hydroxyethyl starch (ANH50) significantly increased M(w) in Group 1 but not in Group 2. In both groups, ANH50 significantly decreased T. ANH50 significantly increased peak E in both groups and peak A in Group 1, and it did not change the E/A ratio or K(c) in either group. ANH causes positive inotropic effects and enhances diastolic function without beta-blockade. Even after beta-adrenergic blockade, ANH improves diastolic function through the reduction of LV ejection impedance.
  
  
  CONCLUSIONS
  Acute normovolemic hemodilution enhances LV (left ventricular) diastolic function by alterations in the LV loading condition produced by hemodilution, which mainly contributes to a compensatory increase in cardiac output.
authors.affiliation: Department of Anesthesiology, Tokushima University School of Medicine, Tokushima, Japan. jnozaki@clin.med.tokushima-u.ac.jp
authors.forename: Junpei
authors.initials: J
authors.lastname: Nozaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitahata
authors.forename: Katsuya
authors.initials: K
authors.lastname: Tanaka
authors.forename: Shinji
authors.initials: S
authors.lastname: Kawahito
authors.forename: Shuzo
authors.initials: S
authors.lastname: Oshita
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D003971:Diastole / Q000187:drug effects*; D004285:Dogs; D005260:Female; D006438:Hemodilution; D008297:Male; D013599:Systole / Q000187:drug effects*; D014655:Vascular Resistance / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects*
chemical_list: D000319:Adrenergic beta-Antagonists