The technique of hypothermic perfusion.

The machine described is in commercial production although the perfusions, to date, were performed with the prototype described by Ross (1960a). The extracorporeal circuit is mounted on the front of the machine (Fig. 1) under the vision of the perfusionist and comprises: Coronary suction reservoir (A) into which all wound and coronary sinus blood is returned by suction from a horizontally mounted de Bakey pump (B). This reservoir contains a filter of six coarse stainless steel meshes and one fine mesh separated by I in. nylon spacers, mounted on a central rod suspended from the cap of the reservoir. This filter is to defoam blood and trap any particles of tissue, fat, or calcium which may return to the circuit. The meshes are coated with silicone antifoam (MS " A "), the only place in the circuit where this substance is used. On the cover of the reservoir is an entry port for the recirculating lead (C) which is used for mixing drugs and maintaining blood temperature during periods of circulatory arrest. There are four 3/16 in. holes drilled in this disc to receive the giving set nozzles used for priming the circuit. The bottom disc is pierced by a I in. hole to receive a lead of X in. " tygon " (D) connecting to the venous reservoir (E). This lead is interrupted by a Y piece connected to an ancillary circuit (F) to bleed the machine should return become embarrassingly profuse. The venous reservoir (E) is a cylinder of clear Perspex 7 cm. in internal diameter with removable top and bottom cover plates which are approximated by rubber 0 rings, rigid rods, and bolts. This makes for ease in cleaning and removes crevices where stale blood may remain and give rise to pyrogenic reactions in subsequent patients. The lower cover plate is