A simple force transducer flow meter system suitable for the Langendorff heart preparation

This paper describes the construction of a simple flow meter for use in preparations such as the Langendorff heart. It enables perfusion of the test tissue to be performed at constant pressure, with the signal produced being immediately compatible with the Ormed range of recording equipment. It requires only simple electronics, without integrators or frequency counters, to produce an average flow rate value over 30-second intervals. Since it is positioned beneath the preparation, it is not susceptible to retrograde flow effects; it is also designed to produce no back pressure. Comparison is made between the device and several other commercially available products. Details are also given of a two-channel system, with minimal components, not requiring an amplifier section. The main aim with the device has been to keep the design simple but adequate.