The hybrid MCL that we developed allows variable and continuous in vitro evaluation of mechanical circulatory support devices in TAH configuration and particularly their control algorithms in response to various cardiovascular conditions. The system has been built in a modular configuration to allow testing of different types of devices and thus provides a valuable test platform prior to animal experiments.

BackgroundGood anatomical compatibility is an important aspect in the development of cardiovascular implants. This work analyzes the interaction of the pump unit of an electrically driven pulsatile Total Artificial Heart (TAH) and the mediastinum. For an adequate compliance, both overall dimensions and alignment of inlets and outlets must be matched.MethodsCross-sectional medical image data of 27 individuals, including male and female patients suffering from end stage heart failure, was segmented and reconstructed to three dimensional (3D) surface models. Dimensions and orientations of relevant structures were identified and analyzed. The TAH surface model was virtually placed in orthotopic position and aligned with atrioventricular valves and big vessels. Additionally seven conventional cadaver studies were performed to validate different pump chamber designs based on virtual findings. Thereby 3D-coordinates were captured and introduced to the virtual environment to allow quantitative comparison between different individuals.ResultsSpatial parameters varied more in male patients with higher values if heart failure persists. Good correlation of the virtual analysis both to literature data and conventional cadaver studies could be shown. The full data of the 27 individuals as well as the summarized values found in literature are enclosed in the appendix. By superimposing the TAH-volume model to the anatomy, various misalignments were found and the TAH-design was adjusted.ConclusionsVirtual fitting allows implant design adjustments in realistic anatomy which has not been influenced by thoracotomy. Higher numbers of relevant individuals can be reasonably investigated in the virtual environment and quantitatively correlated. Using this approach, conventional cadaver studies can be significantly reduced but not obviated, due to the unavailable haptic feedback and immobility of potentially compressed structures.

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Drive optimisation of a pulsatile Total Artificial HeartTotal Artificial Hearts (TAHs) are required for the therapy of terminal heart diseases as heart transplants are only a limited option due to the available number of donor hearts. For implantation TAHs have to meet constraints regarding its dimensions, weight, perfusions and electrical losses. An innovative linear driven TAH is presented, which meets all constraints except weight. Therefore the geometry of the linear drive is optimised to reduce its weights while simultaneously limiting the electrical losses as much as possible. In order to calculate the losses, this paper introduced a combined calculation chain consisting of FEM simulations and analytical equations. Based on this chain the linear drive is optmised by the method of parameter variations. The results yield a hierachic order of parameters which are most suitable for the weight reduction of the drive for low losses. By this the weight of the linear drive is reduced by 25%. As the allowable loss limit is not exceeded yet, room for further weight reduction achieved by an optimisation of the axial geomtry parameters is given.