title: Partial support with a centrifugal left ventricular assist device reduces myocardial oxygen consumption in chronic, ischemic heart failure.
abstract: BACKGROUND
  Left ventricular assist devices (LVAD) are increasingly used for heart failure (CHF); however, the level of optimal support has not been elucidated. We hypothesize that partial LVAD support in an ovine model of microinfarction-induced CHF significantly reduces left ventricular myocardial oxygen consumption (LVVO2).
  
  
  RESULTS
  Microembolization of the circumflex coronary artery was used to induce CHF in 5 sheep (ejection fraction 28 +/- 2%). Four months later, animals underwent implantation of a centrifugal LVAD. LVAD flow was incrementally increased from 0% (baseline) to 25%, 50%, and 75% support of the LV. LVVO2 and stroke work (SW) were calculated at each increment. At baseline, LVVO2 (microL/100 g LV/beat) measured 43.2 +/- 3.4. LVVO2 decreased to 26.5 +/- 8.2,* 20.3 +/- 8.9,* and 12.6 +/- 6.3* at 25%, 50%, and 75% support (*P < .05). SW (mm Hg/mL) measured 1933.0 +/- 275.7 at baseline and decreased to 1588.0 +/- 204.1, 1181.0 +/- 157.2,* and 764.5 +/- 171.7* at 25%, 50%, and 75% support. Cardiac output, heart rate, and left main coronary artery blood flow were unaffected with partial support.
  
  
  CONCLUSIONS
  Complete support with a centrifugal LVAD is not necessary for achieving significant reductions in LVVO2 . Partial support of as little as 25% significantly reduces LVVO2 in CHF through comparatively minor reductions in cardiac work. This is the first study to examine partial LVAD support in a CHF model.
authors.affiliation: Scottsdale Healthcare, Scottsdale, Arizona, USA.
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Goldstein
authors.forename: Gretel
authors.initials: G
authors.lastname: Monreal
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kambara
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Spiwak
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Schlossberg
authors.forename: A Reza
authors.initials: AR
authors.lastname: Abrishamchian
authors.forename: Mark A
authors.initials: MA
authors.lastname: Gerhardt
mesh_terms: D000818:Animals; D003326:Coronary Circulation / Q000502:physiology; D004867:Equipment Design; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006353:Heart-Assist Devices; D017202:Myocardial Ischemia / Q000503:physiopathology / Q000628:therapy*; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D012756:Sheep; D016277:Ventricular Function, Left / Q000502:physiology