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 su rgeons use different approaches. Some try to place the graft as close to th e stenosis as possible, whereas others routinely anastomose the graft onto the distal portion. In this latter case the proximal portion and its tribut aries 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 hemod ynamics associated with the different location of distal anastomoses on flo w patterns in the proximal native artery and its branches. Methods. Computational fluid dynamic and in vitro model studies were carrie d 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 degree s 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 flo w 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 promo te thrombus formation that could ultimately lead to occlusion of the retrog rade portion of the host vessel. Conclusions. This study suggests that, although often less convenient surgi cally, long-term outcome of coronary artery bypass grafting may be improved by placing grafts in the most proximal portion of the native vessel, as cl ose to the occlusion or stenosis as possible for better preservation of a p roximal artery and its branches. (C) 2001 by The Society of Thoracic Surgeo ns.