title: Cardiovascular response to acute normovolemic hemodilution in patients with coronary artery diseases: Assessment with transesophageal echocardiography.
abstract: OBJECTIVE
  Preoperative acute normovolemic hemodilution induces an increase in circulatory output that is thought to be limited in patients with cardiac diseases. Using multiple-plane transesophageal echocardiography, we investigated the mechanisms of cardiovascular adaptation during acute normovolemic hemodilution in patients with severe coronary artery disease.
  
  
  METHODS
  Prospective case-control study.
  
  
  METHODS
  Operating theater in a university hospital.
  
  
  METHODS
  Consecutive patients treated with beta-blockers, scheduled to undergo coronary artery bypass (n = 50).
  
  
  METHODS
  After anesthesia induction, blood withdrawal and isovolemic exchange with iso-oncotic starch (1:1.15 ratio) to achieve a hematocrit value of 28%.
  
  
  RESULTS
  In addition to heart rate and intravascular pressures, echocardiographic recordings were obtained before and after acute normovolemic hemodilution to assess cardiac preload, afterload, and contractility. In a control group, not subjected to acute normovolemic hemodilution, hemodynamic variables remained stable during a 20-min anesthesia period. Following acute normovolemic hemodilution, increases in cardiac stroke volume (+28 +/- 4%; mean +/- sd) were correlated with increases in central venous pressure (+2.0 +/- 1.3 mm Hg; R = .56) and in left ventricular end-diastolic area (+18 +/- 5%, R = .39). The unchanged left ventricular end-systolic wall stress and preload-adjusted maximal power indicated that neither left ventricular afterload nor contractility was affected by acute normovolemic hemodilution. Diastolic left ventricular filling abnormalities (15 of 22 cases) improved in 11 patients and were stable in the remaining four patients. Despite reduction in systemic oxygen delivery (-20.5 +/- 7%, p < .05), there was no evidence for myocardial ischemia (electrocardiogram, left ventricular wall motion abnormalities).
  
  
  CONCLUSIONS
  In anesthetized patients with coronary artery disease, moderate acute normovolemic hemodilution did not compromise left ventricular systolic and diastolic function. Lowering blood viscosity resulted in increased stroke volume that was mainly related to increased venous return and higher cardiac preload.
authors.affiliation: Department of Anesthesiology, Pharmacology and Surgical Intensive Care, University Hospital of Geneva.
authors.forename: Marc
authors.initials: M
authors.lastname: Licker
authors.forename: Christoph
authors.initials: C
authors.lastname: Ellenberger
authors.forename: Jorge
authors.initials: J
authors.lastname: Sierra
authors.forename: Jan
authors.initials: J
authors.lastname: Christenson
authors.forename: John
authors.initials: J
authors.lastname: Diaper
authors.forename: Denis
authors.initials: D
authors.lastname: Morel
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D002320:Cardiovascular Physiological Phenomena; D016022:Case-Control Studies; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000601:surgery*; D004452:Echocardiography; D005260:Female; D006438:Hemodilution; D006439:Hemodynamics; D006801:Humans; D016014:Linear Models; D008297:Male; D011300:Preoperative Care; D011446:Prospective Studies