During vascular surgical operations, there is a need for a simpler and more reliable method of temporary arterial occlusion than those currently employed, especially of heavily calcified arteries. A thermosensitive polymer, LeGoo (LG) (Pluromed, Woburn, MA), has been used successfully for temporary vascular occlusion. It has hitherto been injected by a cannula that has been introduced into the artery to be occluded, here henceforth called the “cannulation method.” Injection into arterial ostia without cannulation, using an injection device that arrests blood flow during the injection, here henceforth called “a retrograde method” may enable temporary hemostasis when ostial stenoses render it impossible to inject LG using the cannulation method. The objective of the present study was to study the feasibility of a retrograde method and to compare it with the cannulation method in an in vitro model, incorporating a narrow orifice to simulate ostial stenosis, using tap water at 37°C instead of blood. The retrograde method of LG injection, using a modified paediatric Foley catheter, turned out to be feasible to produce a durable LG plug more reliably, at higher water pressure and with less deep LG injection than with the cannulation method. 1. Introduction For hemostasis during vascular surgical operations, vascular branches need to be temporarily occluded. This may be accomplished by free dissection and clamping of the branches, which add time and operative trauma to the operation, or by occluding balloons introduced into branch ostia for, for example, visceral and large segmental arteries and stay sutures for small segmental ones, both of which clutters the operative field. A simpler yet rapid and reliable method of temporary arterial occlusion is therefore needed. The more rapidly and reliably bleeding from arterial ostia can be stopped during open aortic and other vascular operations, the less untoward blood loss. LeGoo (LG) (Pluromed, Woburn, MA, USA) is a thermosensitive polymer (20 weight percent of purified poloxamer 407 in saline) that undergoes rapid transition from liquid to a high viscosity gel when warmed from refrigerator temperature to body temperature and has been used successfully for temporary vascular occlusion in, for example, coronary artery bypass surgery. When used for temporary coronary artery occlusion, LG has been injected by a cannula that has been introduced via the arteriotomy into the artery proximally and distally to the arteriotomy, henceforth called the “cannulation method”. Intra-arterial pressure and flow rate have been
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