Developement of pediatric size ventricular assist device for therapeutic use in profound heart failure after open heart surgery.

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In children as in adults, there are many patients who develop profound heart failure after open heart surgery. Since IABP and veno-arterial bypass are not effective and complicated, more effective and safer cardiac assistance is needed. So we have developed pediatric size air-driven and diaphragm type ventricular assist device(VAD) for children. Its stroke volume is 20 ml and it is made of segmented polyether polyurethane(TOYOBO TM-series) and contains two #21 Bjork-Shiley valves. The conduits are made of polyvinylchloride and their inner surface is coated with TM-3. The IDs of inlet and outlet conduet are 6 and 8 mm. The control drive unit is the same as that developed for adult use in our center.In vitro performance demonstrated that the pump could yield sufficient flow and had a good ability to follow tachycardia.The results of the chronic animal experiments using young goats(body weight: 9-17 kg) indicated that VAD for children had excellent in vivo performance in several aspects. These included ease of implantation, sufficient capability for circulrtory support, good antithrombogenicity, high durability and no harm on the blood chemistry of young and immature animals.And we had one clinical case. He was 3 year-old boy and operation was done for ventricular septal defect. After that he could not be weaned from extracorporeal circulation, so this VAD was applied.The entire circulation was well maintained and he was weaned from VAD after 3 days pumping because of his heart recovery.So we believe this VAD can be an effective and safe approach for treating the child with postoperative profound heart failure.