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Selected aspects of the application of the hybrid circulatory system in the analysis of heart insufficiency

Milewski Grzegorz, Rumian Stanisław, Kopacz Michał, Ciszkiewicz Adam

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 2

153--161

EN

There are many causes of heart failure, one of them being valvular heart disease. In this case, the stage and type of the disease can significantly affect the hemodynamic parameters of the left ventricle of the heart. In turn, these parameters can significantly influence the mode, type and strategy of clinical treatment. The aim of the study was to analyze and map the hydrodynamic conditions of the heart using a hybrid-digital model of the circulatory system. Methods: The tests performed using the circulatory system model allowed for the simulation of the failure of both heart’s left ventricle and a set of arteries in the systemic circulation. Furthermore, the changes in hemodynamic parameters for valvular anomalies at various heartbeats were obtained. Results: The results suggested that a higher heartbeat should be sustained in such cases of complex mitral-aortic anomalies in the clinical practice. When observing low aortic pressures, heartbeat should be increased to compensate for the valvular insufficiencies. Conclusions: Extending the already conducted research could result in constituting a wide database for clinicians who are treating the insufficiency of the left ventricle of the heart. Moreover, the information included in this paper may be used for a comparison of the clinical anomalies, which facilitates a correct diagnosis. The test-stand used in the research can be applied to predict the anomalies of the circulation system for a quick and precise analysis of a clinical anomaly of a patient without physical presence.

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Differential evolution and cost-maps for needle path planning in Baker’s cyst aspiration

Ciszkiewicz Adam, Lorkowski Jacek, Milewski Grzegorz

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 4

39--47

EN

The Baker’s cysts appear within the popliteal fossa along with the progression of degenerative changes. Removal of its contents through aspiration is often a necessary complement to treatment at various stages of the development of gonarthritis. Methods: The paper presented a procedure for needle automatic needle path planning in cyst aspiration in transverse plane. The method was based on optimization and used a custom objective function, which utilized cost maps obtained from preprocessed, segmented images of the knee. The optimization was carried out with Differential Evolution. Furthermore, a preliminary sensitivity analysis was carried out. The obtained paths were compared to the reference paths proposed by an experienced surgeon. Results: The procedure was tested on 165 numerical simulations. In all of the obtained paths, the needle successfully avoided crucial objects, such as veins, arteries and nerves. Furthermore, the overall travel distance in the joint was also minimized. When compared to the reference from the surgeon, 90% of the paths were almost the same or only slightly different. Furthermore, the remaining 10% of the generated paths were viable but different. Conclusion: Based on the obtained results, the proposed solution could be a viable solution for planning the aspiration of Baker’s cyst.

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Stress relaxation phenomena in polymeric orthodontic ligatures

Milewski Grzegorz

Engineering of Biomaterials

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2021

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Vol. 24, no. 162

2--6

EN

Elastomeric products are applied in orthodontics mainly as elastic ligatures or chains and have become an alternative to wire ligation made of titanium alloy or stainless steel. Despite their popularity among the dentists and undoubtful advantages, some essential warnings are being raised regarding the degree of load loss. This relaxation phenomenon seems to be a dominant feature in the time-dependent behaviour of those elements in orthodontic procedures, such as dentition corrections or teeth extrusions. The aim of the paper was to examine and analyse the rheological properties of biocompatible orthodontic elastomeric ligatures. Five different polymeric orthodontic ligatures were examined in the following experiments: a simple relaxation test, relaxation simulating orthodontic extrusion and the two-steps relaxation process, which stands for so-called ‘secondary tightening’, resulting in the increase of the orthodontic force. The results of the relaxation experiments proved that among various descriptions of that phenomenon, the power-law descriptions fit the best time-dependent behaviour during orthodontic procedures. Power-law models give the most intensive initial relaxation, which is characteristic for elastomeric ligatures. The obtained results and analyses allow precise control of the treatment progress in the orthodontic extrusion procedure.