Hemostatic Control of Coronary Arteries With Poloxamer 407 Reverse-Thermal Polymer During Off-Pump Coronary Artery Bypass Surgery in a Pig Model

Objective: To evaluate a new material, poloxamer 407 reversethermal polymer, which may be of value in controlling bleeding during off-pump coronary anastomoses. Methods: Poloxamer 407 reverse-thermal polymer is a clear, nontoxic compound that is a viscous liquid at room temperature but instantly changes to a firm, water-soluble gel when warmed to body temperature. Six pigs underwent off-pump coronary artery bypass with the left internal mammary artery to the left anterior descending coronary artery. Blood loss from the arteriotomy was measured over a 15-minute period before and after injection of 500 mu L intracoronary polymer. After completion of the anastomosis, 10 mL of cold saline was poured along the left anterior descending artery to facilitate dissolution of the polymer. The heart was allowed to beat 2 additional hours with blood flowing through the left internal mammary to left anterior descending graft, after which a completion angiogram was obtained to evaluate graft patency and to look for gross angiographic evidence of coronary branch occlusion or intraluminal filling defects. The animals were then humanely euthanized, and myocardium from the area subtended by the left anterior descending was harvested for histologic evaluation. Results: All animals successfully underwent the surgical procedure and survived until study termination without any complications. The amount of bleeding from coronary arteriotomy was significantly higher before intracoronary injection of the polymer (5.25 +/- 1.65 mL/min versus 0.54 +/- 0.53 mL/min, P = 0.0004). Angiography demonstrated that the graft was patent, and there was no evidence of intraluminal foreign bodies. Myocardial samples from the subtended bed showed no evidence of intraarterial polymer or myonecrosis. Conclusions: Poloxamer 407 reverse-thermal polymer may be a valuable tool in performing coronary anastomoses off-pump. Completion angiograms showed total dissolution of the material with no residual intraarterial polymer visible on tissue samples.