A rapid in vitro screening protocol to guide selection and monitoring of polymers for implant or extracorporeal applications is described. There are four main procedures under the protocol: 1) and 2) measurement of physical property change over thermal and simulated biochemical stress, 3) infrared spectrophotometric assay of migratible species developed over simulated biochemical stress, and 4) cell culture sensitivity to those migratible species. In vivo biochemical stress was simulated and accelerated by exposing polymer specimens to a pseudoextracellular fluid (PECF) at 120°C for 62 hr.Results from procedures 3) and 4) are presented. These show a good correlation between cell culture response and the total carbon-hydrogen bonds developed in the PSF over the exposure period. Correlation of these data with available clinical and animal implant experience is consistent and is discussed in detail. Infrared assays for a candidate polymer may be obtained at relatively low cost within 4 days and stand as a rational basis for rejection or retention for preclinical in vivo studies.
A multidiscipline group was established at The Pennsylvania State University to design and evaluate mechanical circulatory assist devices and the artificial heart. The group has designed a left ventricular to aortic assist system which consists of a sac-type pump, a synchronization unit, a pneumatic power unit, and appropriate monitoring apparatus. The assist system has been evaluated for long-term circulatory assistance in a series of ten calves. The assist pump was placed in the paracorporeal position. The longest period of continuous pumping was over eight months. The last four calves have had synchronized assist pumping which has permitted prolonged ventricular decompression and assist pump flow rates as high as 10 L/min. Three of these four calves had no evidence of thromboemboli. Additional animal studies will be required before clinical use of such an assist pump system can be safely undertaken.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.