title: Vertical displacement of the beating heart by the octopus tissue stabilizer: influence on coronary flow.
abstract: BACKGROUND
  In beating heart coronary artery bypass graft operations, biventricular pump failure, as observed after exposure of the posterior circumflex branches by sternotomy, may originate from mechanical obstruction to coronary flow.
  
  
  METHODS
  Regional coronary blood flow was measured in 8 anesthetized, paced, beta-blocked pigs, and the beating heart was fully retracted.
  
  
  RESULTS
  Displacement decreased cardiac output from 4.8 +/- 1.1 L/min (mean +/- standard deviation) to 2.8 +/- 1.2 L/min (p < 0.001), a 42% +/- 6% decrease that resulted in a decrease in mean arterial pressure by 48% +/- 6% (mean +/- standard error of the mean; p < 0.001) and a reduction in coronary blood flow in the left anterior descending coronary artery, the right coronary artery, and the circumflex coronary artery by 34% +/- 6%, 25% +/- 8%, and 50% +/- 10%, respectively (all p < 0.05 versus baseline). Relative circumflex coronary artery flow was 20.1% +/- 8.3% lower than the combined relative value of left anterior descending coronary artery and right coronary artery flows (p = 0.046). Subsequent 20 degrees head-down tilt significantly increased ventricular preload pressures and restored cardiac output and mean arterial pressure as well as coronary blood flow.
  
  
  CONCLUSIONS
  It is inferred that coronary blood flow was not mechanically obstructed during anterior displacement of the porcine beating heart, because augmentation of preloads by the maneuver of Trendelenburg restored coronary flow parallel to the recovery of cardiac output and mean arterial pressure while the heart remained retracted by 90 degrees.
authors.affiliation: Department of Cardiology, Heart Lung Institute, Utrecht University Hospital, The Netherlands. exp.cardio@hli.azu.nl
authors.forename: P F
authors.initials: PF
authors.lastname: Gründeman
authors.forename: C
authors.initials: C
authors.lastname: Borst
authors.forename: J A
authors.initials: JA
authors.lastname: van Herwaarden
authors.forename: C W
authors.initials: CW
authors.lastname: Verlaan
authors.forename: E W
authors.initials: EW
authors.lastname: Jansen
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D002303:Cardiac Output, Low / Q000209:etiology; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000473:pathology; D018475:Head-Down Tilt; D006321:Heart / Q000033:anatomy & histology*; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption; D013249:Sternum / Q000601:surgery; D013318:Stroke Volume; D013552:Swine; D013908:Thoracotomy / Q000009:adverse effects; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right; D017725:Ventricular Pressure