The Radnoti Hi-Tech Heart Chamber has been designed for researchers using either Langendorff or working heart systems. The chamber incorporates a number of features found in no other system. The chamber is fully water-jacketed using Radnoti Quick Disconnect fittings to permit easy removal from the rest of the system for cleaning. Both the chamber body and lid are independently mounted on support rods for easy positioning. The chamber has four ports in the chamber lid for insertion of instrumentation such as balloon catheters, electrodes, fiber-optic cables, cannulae, etc. The chamber lid is secured with a threaded ring, which permits sealing the chamber for reduced heat loss and purging of the chamber interior with gas mixtures. Two of the lid access ports are placed on a locking cam for easy positioning and securing of mounting cannulae, which come in a variety of sizes. The cannulae are fitted into the ports using collars, which allow the cannulae to be rapidly extended or retracted and then locked into place. At the bottom of the chamber is a removable pulley which inserts into the chamber interior and is used for apical force measurements. This pulley can be easily positioned as it is secured with a collar tightened from the outside of the bath. A suture is secured to the heart and the line passed around the pulley and through the hollow pulley support arm using a wire loop provided. To close the chamber, the chamber body is slid up to the lid, the threaded ring is tightened, and then the suture is tied to the force transducer. The benefits of this system are improved temperature control, the maintenance of a perpendicular line to the transducer and the virtual elimination of perfusate aerosols, an important consideration when working with isotopes. To enhance collection of perfusate, the bottom of the chamber funnels the effluent into a tapered ground glass fitting which directs the flow out of the chamber. The Radnoti Hi-Tech Chamber is designed in three sizes: Small (rat, guinea pig); Medium (cat, rabbit); and Large (porcine) isolated heart preparations. This chamber can be retrofitted into older Radnoti heart systems. Stainless steel cannulae may be ordered as an option