Q-PULS, a new quasi-physiological pulsatile extracorporeal model to simulate heart function

OBJECTIVES: The invention of new surgical procedures requires testing at different stages including animal models. To facilitate this process, we have developed a computer-controlled extracorporeal circulation system for testing of an explanted porcine heart simulating a variety of physiological parameters. Mitral valve function can be assessed before and after induced valve insufficiency and after valve repair. Accordingly, techniques and instruments can be modified at early stages of prototype development. METHODS: In the diastole, the left atrium is passively filled through the reservoir. The loading pressure of the atrium and flow rates can be widely adjusted. To simulate the systole, a linear motor-driven piston pump promotes volume into the left ventricle and the aorta. An additional circulatory pump compensates for undesired total emptying of the heart chambers. The processor control of the linear pump allows for various settings of flow rate, velocity and even irregular rhythm. Twenty-one isolated porcine hearts were used. The leaflet movement was filmed using a universal serial bus (USB)-probe camera. RESULTS: With 80 mm stroke and 1 m/s speed, a volume of 150 ml can be pumped at a heart rate of up to 73 bpm. Cardiac outputs of up to 10.9 l/min can be achieved. Constant visualization and continuous measurements of the pressure gradients before and after the induction of mitral insufficiency and after repair allowed quantitative verification of repair quality under beating-heart conditions. CONCLUSIONS: This model allows a controllable pulsation, loading and unloading of a porcine heart in a wide range. Thus, the function of the leaflets and repair results can be qualitatively and quantitatively evaluated under quasiphysiological conditions.