Long-term function of biological heart valve prostheses (BHV) is limited by structural deterioration leading to failure with associated arterial hypertension. The objective of this work was development of an easy to handle real-time pulse reactor for evaluation of biological and tissue engineered heart valves under different pressures and long-term conditions. The pulse reactor was made of medical grade materials for placement in a 37 degrees C incubator. Heart valves were mounted in a housing disc moving horizontally in culture medium within a cylindrical culture reservoir. The microprocessor-controlled system was driven by pressure resulting in a cardiac-like cycle enabling competent opening and closing of the leaflets with adjustable pulse rates and pressures between 0.25 to 2 Hz and up to 180/80 mmHg, respectively. A custom-made imaging system with an integrated high-speed camera and image processing software allow calculation of effective orifice areas during cardiac cycle. This simple pulse reactor design allows reproducible generation of patient-like pressure conditions and data collection during long-term experiments.
A home-made slam freezing device is presented that allows reproducible results in freezing various unfixed tissues. The heart of the device is an aluminum socket, which harbors a plunger that is set in motion by a spring. At the end of the plunger there is an electromagnet which holds the sample on a sheet metal planchette. During stop freezing the electrical contacts are interrupted and the plunger can be withdrawn leaving the specimen on the cooled copper block. This guarantees freezing of not only solid tissues, but also cell suspensions, such as blood or bone marrow.
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