HEMODYNAMIC-CHANGES DURING DISPLACEMENT OF THE BEATING HEART BY THE UTRECHT OCTOPUS METHOD

Background. Coronary bypass grafting of posterior circumflex branches requires full displacement of the heart (apex pointing ventrally), whi ch, in the beating heart, results in an arterial pressure drop. We ana lyzed its origin. Methods. To facilitate displacement, the Utrecht ''O ctopus'' method was applied in 8 anesthetized beta-blocked pigs and th e beating heart was fully retracted. Results. Displacement decreased s troke volume from 75 +/- 17 mL (mean +/- standard deviation) to 43 +/- 13 mL (p < 0.001), a 44% +/- 3% decrease that resulted in a decrease in cardiac output by 32% +/- 5% (mean +/- standard error of the mean; p < 0.001), a decrease in mean arterial pressure by 26% +/- 5% (p < 0. 01), and an increase in heart rate by 26% +/- 6% (p < 0.01). Right ven tricular end-diastolic pressure increased from 5 +/- 1 to 8 +/- 1 mm H g (p < 0.01). Twenty degrees head-down tilt normalized cardiac output and mean arterial pressure. Right ventricular end-diastolic pressure i ncreased to 10 +/- 2 mm Hg (p < 0.001) and left ventricular end-diasto lic pressure to 11 +/- 3 mm Hg (p < 0.01). Conclusions. Displacement o f the beating heart in the pig induced a 44% drop in stroke volume, wh ich is attributed to biventricular interference with pump function. Th e Trendelenburg maneuver reestablished the control circulatory status at the expense of augmented right and left ventricular preloads and an increased heart rate. (C) 1997 by The Society of Thoracic Surgeons.