Control of perfusion pressure and flow in isolated heart bioassays

Bioassays using isolated animal hearts are important tools for the investigation of cardiac behaviour, but to obtain accurate results a proper perfusion circuit has to be designed. In particular, biophysical studies of contractile and vascular behaviour require a perfusion circuit which permits the adjustment of several experimental parameters within wide ranges. It must also be able to maintain the stability of these parameters when the behaviour of the isolated organ undergoes major changes. To meet this requirement, we have developed a perfusion circuit which makes it possible to control either the perfusion pressure or the coronary flow, with a high degree of precision. There is an electronic controller which satisfies the requirements of a variety of safety and experimental requirements and guarantees a well-defined perfusion system. Computer simulation of the interaction between the perfusion circuit and the heart identified the basic elements of this time-variable, nonlinear system.