title: Evaluation of hemodynamics: comparison of vacuum and mechanical stabilization in the beating heart.
abstract: BACKGROUND
  Hemodynamic instability remains a prominent concern for surgeons performing coronary surgery without cardiopulmonary bypass. The purpose of this study was to further elucidate the mechanism of hemodynamic instability by comparing vacuum stabilization to mechanical stabilization.
  
  
  METHODS
  Four 60-kg swine were placed under general anesthesia. A median sternotomy incision was made, and baseline hemodynamic measurements were recorded. Mechanical and vacuum stabilization of the circumflex distribution were alternately compared with repeated baseline measurements in a counterbalanced method, and 32 experiments were conducted.
  
  
  RESULTS
  There were significant differences between baseline hemodynamics and stabilized hemodynamics for mechanical stabilization versus vacuum stabilization, respectively, for the following parameters: blood pressure (mean decrement), -32.18% (P =.0028) versus -31.3% (P =.0006); cardiac output, -31.03% (P =.0046) versus -35.2% (P =.03); and mixed venous oxygen saturation, -29.8% (P =.008) versus -27.4% (P =.0004). There were no statistical differences between mechanical and vacuum stabilization when their decremental effects on baseline hemodynamics were compared with each other for any of the measured variables.
  
  
  CONCLUSIONS
  The mechanisms of hemodynamic compromise during coronary stabilization remain to be fully elucidated. Our study demonstrates no statistical difference between vacuum and mechanical stabilization on the measured hemodynamic values. More sophisticated studies involving detailed analysis of motion and geometry are required so that technical solutions to hemodynamic instability can be developed.
authors.affiliation: CorVasc and Methodist Hospital, Indianapolis, Indiana, USA. danbeckman@comcast.net
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Beckman
authors.forename: Karen
authors.initials: K
authors.lastname: Bumb
authors.forename: Maria
authors.initials: M
authors.lastname: Bandy
authors.forename: Maria
authors.initials: M
authors.lastname: Evans
authors.forename: Cindy
authors.initials: C
authors.lastname: Romanyk
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000379:methods; D006439:Hemodynamics / Q000502:physiology*; D013552:Swine