title: Right heart mini-pump bypass for coronary artery bypass grafting: experimental study.
abstract: BACKGROUND
  Visualization of the left circumflex arteries during off-pump coronary artery bypass grafting (CABG) causes hemodynamic disturbance. We investigated whether right heart mini-pump bypass (RHB), using a centrifugal pump, improved the safety of this procedure by studying the influences of different heart displacement positions, the Trendelenburg maneuver and RHB on hemodynamics.
  
  
  METHODS
  Hemodynamic parameters in eight mongrel dogs (15.5-20 kg) were continuously monitored at a fixed heart rate of 80 beats/min through a conventional median sternotomy. The posterior descending artery (PDA) and left circumflex artery (LCX) were exposed using an Octopus tissue stabilizer. After evaluating the influence of the Trendelenburg maneuver on hemodynamics, a heparin-coated centrifugal pump without an oxygenator was introduced and the impact of different pump flow volumes was investigated during RHB.
  
  
  RESULTS
  LCX exposure caused significant decreases in aortic flow (to 35. 1+/-12.8%) and arterial mean pressure (to 66.1+/-9.3%) compared with baseline (P<0.001). In contrast to PDA exposure, values remained significantly decreased during the Trendelenburg maneuver. On the contrary, RHB significantly improved the hemodynamic impairments caused by both heart displacement procedures, especially LCX exposure, although 100% pump flow significantly increased left atrial pressure to 131.3+/-19.5% (P<0.01).
  
  
  CONCLUSIONS
  Exposure of the LCX caused severe hemodynamic deterioration, which was not fully reversed by the Trendelenburg maneuver. In contrast, RHB significantly improved hemodynamics, and therefore this technique can be beneficial for CABG of LCX in the limited cases.
authors.affiliation: Department of Cardiothoracic Surgery, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, 113-8655, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Suematsu
authors.forename: T
authors.initials: T
authors.lastname: Ohtsuka
authors.forename: K
authors.initials: K
authors.lastname: Miyaji
authors.forename: A
authors.initials: A
authors.lastname: Murakami
authors.forename: T
authors.initials: T
authors.lastname: Miyairi
authors.forename: Z
authors.initials: Z
authors.lastname: Eyileten
authors.forename: Y
authors.initials: Y
authors.lastname: Kotsuka
authors.forename: S
authors.initials: S
authors.lastname: Takamoto
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002315:Cardiopulmonary Bypass / Q000295:instrumentation*; D001026:Coronary Artery Bypass; D004285:Dogs; D004867:Equipment Design; D005240:Feasibility Studies; D006353:Heart-Assist Devices; D016278:Ventricular Function, Right / Q000502:physiology