Effect of distal graft anastomosis site on retrograde perfusion and flow patterns of native coronary vasculature

Background. To select the site of a target vessel for distal anastomosis surgeons use different approaches. Some try to place the graft as close to the stenosis as possible, whereas others routinely anastomose the graft onto the distal portion. In this latter case the proximal portion and its tributaries are perfused from the graft in a retrograde rather than an antegrade fashion. The aim of this study was to investigate the effect of local hemodynamics associated with the different location of distal anastomoses on flow patterns in the proximal native artery and its branches. Methods. Computational fluid dynamic and in vitro model studies were carried out in a control model composed of a straight tube (host) with a 45E side branch and models in which the proximal end of the host had various degrees of stenosis; a 45E end-to-side "graft" anastomosis was introduced either proximal (upstream) or distal (downstream) to the branch. Results. Placing the graft proximal to the branch largely preserved the flow patterns that were seen in the control model. Placing the graft distal to the branch, however, introduced an extensive region of relatively stagnant flow in the native vessel near the branch. Such regions are known to promote thrombus formation that could ultimately lead to occlusion of the retrograde portion of the host vessel. Conclusions. This study suggests that, although often less convenient surgically, long-term outcome of coronary artery bypass grafting may be improved by placing grafts in the most proximal portion of the native vessel, as close to the occlusion or stenosis as possible for better preservation of a proximal artery and its branches. (C) 2001 by The Society of Thoracic Surgeons.