During the re-circulating of perfusate, the heart releases proteins that cause foaming and the formation of embolites. To remove these proteins and other precipitates that may exist in the solution, this filter is inserted in the pump output line. The filter may then be removed at the end of the experiment and replaced before the next experiment is started. This is an improvement over systems that incorporate the filter as a permanent fixture in the design, necessitating extensive cleaning procedures of the entire apparatus after each use. Polytetrafluorethylene (PTFE) membranes are unaffected by most organic solvents, concentrated acids and bases, propellants, and cryogenic fluids. Can be used for gas/air filtration. Use caution with syringes less than 10cc. For laboratory use only.