Study On Ventricular Assisted Device Comprises Of New Type Polyurethane And Evaluation Of Its Histocompatibility

Cardiovascular disease is regarded as the top killer of human being and it causes a mortality above 40% in all the dead in the western countries. With the ageing of people, with the widely using of cardiovascular drugs and with the improving of the standard of living, the morbidity of cardiovascular disease was rising year by year. It is indicated by research that those had a level IV cardiac function and their livability over one-year is about 40-50%. The current methods for heart failure treatment include the routine drug treatment, heart transplantation and application of the VAD (ventricular assist device). The routine drug treatment has a limited effect. It is also limited by heart transplantation because of the shortage of heart donor and the problems of economy or medicine. The VAD is considered as the most effective treatment for the heart failure. The failure heart could recovery and maintain the circulation or could pull through to the heart transplantation with partly or completely support by the VAD. The external VAD has a long history over 40 years. It had been developed and made better step by step. Now it plays great role in the treatment of heart failure. However, hemolysis, thrombosis and long-term application remained of major importance in the daily practice of VAD. The complication of hemolysis, thrombosis and mechanical valve degeneration, bad haemocompatibility are all associated with the biocompatibility of materials and the manufacture technique. It is the hot issue in the field of medicine and biomaterials to work on and develop new materials and the VAD. And it is also marketable and expectable.Part 1 study on biocompatibility about modify polyurethane materialsIn this part, organosilicon was added to modify the soft-segment or hard-segment of the medical polyurethane(PU). There were five test groups in this experiment and they were hard-segment modified PU group, soft-segment modified PU group, pure PU group, medical Polyvinyl chloride(PVC) group and silastic group. Then haemocompatibility and histocompatibility were observed in each groups. The haemocompatibility test included that hemolysis test, dynamic clotting time test and platelet adhesion test. The histocompatibility test included that acute systemic toxicity test in rats, skin stimulation test and local response test of embedded muscle and the cytotoxicity evaluation test by cell culture and 3-(4,5-dimethylthiazole-2-yl)-2-5-diphenytetrazolium bromide (MTT) assay and the test of RNA synthesis .Results. The hemolysis test shows that the hemolysis index in hard-segment (0.642%) or soft-segment(0.693%) modified PU group is better than that in pure PU group( 1.798%), in medical PVC group (2.992%) and in silastic group( 1.027%). The dynamic clotting time test shows that the antithrombogenicity in hard-segment or soft-segment modified PU group is better than that in non-modified PU group (P<0.05).The results in silastic group shows no difference and the silastic has similar antithrombogenicity with the hard-segment or soft-segment modified PUs. But the medical PVC has a worse antithrombogenicity than that in other groups(P<0.01). The platelet adhesion test shows that the adhesion ratio is lowest in hard-segment or soft-segment modified PU groups and that in medical PVC group is highest. The hard-segment orsoft-segment modified PUs are better than the pure PU (P<0.05). The other mentioned tests are used to evaluate the biocompatibility of materials from general histological level to cellular level. All of these tests show that PVC has bad biocompatibility, pure PU and silasitic have good biocompatibility and the biocompatibility in hard-segment or soft-segment modified PUs are better.Conclusions: The PU has better haemocompatibility or biocompatibility than the other medical materials, such as the PVC or the silastic. The organosilicon is added to modify the hard-segment or the soft-segment of the PU and makes the haemocompatibility or biocompatibility better.Part 2 Study and manufacture of a pulsatile VADThe me...