Development And Study Of Heparin Coated Cardiopulmonary Bypass Circuits

Cardiopulmonary bypass(CPB) is a basic method in treating various heart diseases. CPB devices consist of connecting CPB circuits, oxygenator, reservoir, arterial microsphere filter components et al. Heparin-coating technology ,matured for nearly 20 years, has been shown to increase biocompatibility of the CPB material. Clinical application of heparin-coated circuits is an effective option during CPB. The domestic use of heparin binding technology equipment is rare due to overall medical costs. Few studies of cardiopulmonary bypass equipment coated were done, mainly in basic research with methods of operation complexity. Our group with the department of applied chemistry, Xi'an Jiaotong University developed a heparin -PEI surface modification technology with independent intellectual property. Through the introduction of reactive amino onto medical polyvinyl chloride material (PVC) and the glutaraldehyde as covalent hinge, heparin molecules are combined on the surface of biological materials. Initial method was suggested that simultaneously ionic and covalent binding of two ways, in 2005 with a patent (ZL03108086.3). On this basis, we further optimized the concentration and molecular weight of coupling agent polyethylenemine, screened the rate of heparin release to evaluate the stability of heparin coating.【Objective】To screen the detail of PEI-G-H coating process and test its heparin coating stability.【Methods]】1. PEI-G-H-coated cardiopulmonary bypass (CPB)circuits was prepared to take the mass fraction of 1g/dL, 2g/dL, 5g/dL all 100ml with PEI solution of average relative molecular weight 3000,10000,20000, by solvent of anhydrous ethanol at 37℃,simultaneously, by control with the cross-linking agent not heparin-coated circuits. With infrared absorption peak of infrared spectrum, PEI-G-H coated cardiopulmonary bypass circuits were characterized in each group width highly different, representative of different qualitative and quantitative trends of heparin. With reaction of concentration of heparin solution and the same amount of toluidine blue, the concentration of free heparin is calculated by the standard curve to capacity at the absorbance value at 631nm. Heparin concentration was determined by measuring the response remaining after toluidine blue solution at the absorbance at 631nm with standard concentration of heparin working curve. Polyethyleneimine molecular weight, concentration and pH, solvent and other factors are affected on the combined heparin.2. 16 groups of PEI-G-H coated medical polyvinyl chloride material(PVC) treated by the same process were randomly divided into two groups, through the in vitro bypass by control to soak method, with 1,2,4,8,16,32,64,128 toluidine blue Spectrophotometer of heparin release rates, the stability of heparin coating is evaluated. The stability of heparin-binding material is assessed by heparin releasing rates.【Results】Content of heparin coating material surface and toluidine blue absorbance (A) has good positive correlation (regression coefficient R = 0.999). By toluidine blue solution spectrophotometry, the content of free heparin were accurately measured in the 0 ~ 850μg / cm2 range. In several heparin-binding surface, the average molecular weight of 20,000, the quality of materials combined with heparin fraction 2g/dl more, for the same molecular weight polyethylenemine coating materials, heparin-binding capacity by mass fraction; the group of heparin-coated materials heparin concentration by the average molecular weight of PEI impact (p <0.05), and the mass fraction of each groupThe simulation of the coating material after cardiopulmonary bypass with heparin coating immersion control group treated by soaking each time point measured loss rate of 128 hours, two heparin-binding surface have different levels of heparin off phenomenon, immersion heparin-combined surface was 0.108-0.825 off, the treated material by the combination of heparin surface loss rate of 0.13-0.92 , cardiopulmonary bypass Group combination of surface material loss rate of heparin combined with the immersion material loss rate of the surface of heparin molecules was no significant difference between them (p> 0.05)【Conclusion】1. A lot of heparin was combined on PVC material surface with Polyethylene mine as the crosslinking agent, glutaraldehyde as incremental agent. Whereas, PEI has an important role in heparin- combined volume affected by concentration of heparin, molecular weight of PEI and many other factors.2 . In simulated CPB, saline by the bypass was primed in the machine. Extender Lateral shear force is an increase for the use of heparin coating material closer to the status of surgery suggesting that heparin falling rates were low, and the kind of heparin coating method can be suitable for clinical use in result.