Development of long term use menbrane oxygenator built-in artificial heart

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As the heart and lung frequently fail simultaneously due to the extensive interaction of these closely related organs, it has been expected to develop such a device as to support these organs at the same time. On the basis of this back ground, we have developed a novel assist system for long-term cardiopulmonary support ; an integrated artificial heart-lung device (IAHLD). The IAHLD consists of a compact oxygenator and two pneumatic pusher-plate type artificial hearts. The oxygenator is made of two layred non-porous membrane hollow fibers in which an ultrathin dense layr formed at the blood contacting surface prevents serum leakage. The fibers are potted in a cylindrical polyurethane potting (phi60 mm X 70 mm) which also serves as a housing. The artificial heart has an inlet (or outlet) port with a Bjork-Shiley valve and a coupler of 60 mm in diameter. The artificial heart are coupled to each and of the oxygenator with the coupler ; thus all components are incorporated. With this special structure, we intended to avoid low flow areas, which causes thrombus formation and gas exchange deterioration. The gas transfer performance of the prototype device (gas exchange area =1.5m^2, priming volume = 400 ml) was 300 ml/min for oxygen and 250 ml/min for carbon dioxide at a blood flow rate of 5 L/min. Venoarterial bypass using the prototype device could satisfactory replace the total cardiopulmonary function in a nonfunctioning heart-lung model of a goat weighing 60 kg. During 6 hours of pumping, hemodynamic parameters of the goat was maintained fairly stable and blood gas data was kept above 300 mmHg for PaO_2 and below 30 mmHg for PaCO_2. We are also developing a technique for thromboresistant surface treatment : covalent heparin bonding technique. Although this research is still premature, we believe that we can make it practical in a near future.