Mariusz Pawlak

Estimation of kinematic parameters in a model of artificial aortic valve leaflets

Currently, one of the least invasive methods of replacing a dysfunctional aortic valve in humans is Transcatheter Aortic Valve Implantation (TAVI). The shapes of expandable stents have an influence on the geometry of the leaflets and differ from those mounted by open heart valve surgery. There are different types of balloon and selfexpandable TAVI valves. For the purposes of analysis of the influence of constraints on the kinematic parameters of aortic valve leaflets, prototype leaflets were made of polyurethanes. Results from the numerical model and a machine for testing the durability of the heart valve are presented.

Validation of the Numerical Model of Impuls I Electric Multiple Unit Driver’s Cab

The article presents the validation of a numerical model of the electric multiple unit (EMU) driver’s cab. The subject of the study was the cab of the driver of the Impuls I rail vehicle of Newag S.A. The numerical model was developed in the LS-Dyna environment based on the documentation received from the manufacturer. The driver’s cab was modelled as shell elements, the additional parts required for the crash test were modelled as solid elements. Experimental research was carried out on the order of Newag S.A. on the experimental track of the Railway Institute in Weglewo near Zmigrod according to PN-EN 15227. The collision was recorded by 3 cameras used for fast changing phenomena. Additionally, acceleration sensors were placed at specific locations of the construction. The article presents results from experimental research and their comparison with the results of numerical simulation.

Charpy Impact Testing Machine in Modeling of Vehicle Frontal Crash with Street Lights

Real tests of a crash of a vehicle with lighting column are an expensive but necessary part of norm EN-126767:2008. During the design process of lighting columns, it is necessary to provide some modifications to receive sufficient safety class. To not repeat the experiments and to reduce the costs, numerical simulations are carried out, and when finally good results are received, a real crash test of a vehicle with real size streetlight can be performed. However, a truly challenging problem is the validation of the numerical models without experiments and making a good conclusion based on them. To investigate if something else than a real car crash experiments can be used, a small model of a Charpy Impact testing machine was created. The pendulum mass, the location of striking edge and radius of the striking edge can be altered in the model. The location of the mass center of the obstacle with which the crash is to be observed is also important. Experimental results from the testing machine were collected and compared with results from numerical simulations and conclusions were drawn.

State-of-the-art of transcatheter treatment of aortic valve stenosis and the overview of the inflow project aiming at developing the first Polish TAVI system

Initial experience of transcatheter aortic valve implantation (TAVI) or replacement (TAVR) has ap-peared as a promising minimally invasive technology for patients disqualified from surgical treatment (SAVR). Safety and efficacy of TAVI has been analyzed and assessed through numerous registries and trials. Furthermore, results obtained from comparative TAVI vs. SAVR trials proved that both treat¬ments can be considered equal in terms of post-procedural mortality and morbidity in high-risk, as well as lower risk patients. However, there are still some issues that have to be addressed, such as higher chance of paravalvular leakage, vascular injuries, conduction disturbances, malpositioning and the yet unmet problem of insufficient biological valves durability. Recent technological developments along with the learning curve of operators prove a great potential for improvement of TAVI and a chance of surpassing SAVR in various groups of patients in the near future. In pursuit of finding new solutions, the CardValve Consortium consisting of leading scientific and research institutions in Poland has been created. Under the name of InFlow and financial support from the National Center for Research and Development, they have started a project with the aim to design, create and implement into clinical practice the first, Polish, low-profile TAVI valve system, utilizing not only biological but also artificial, polymeric-based prosthesis. This review focuses on current developments in TAVI technologies including the InFlow project.

Preliminary tests of new composite material based on shape memory alloys for artificial aortic valve leaflets

Nowadays bioengineers actively search for new materials for different kind of implants. The natural tissues used for these purposes have many defects, of which the most important is the possibility of transplant rejection. However, properties of artificial biomaterials have also many deficiencies among which there are insufficient mechanical and fatigue properties. The example of this can be the aortic valve leaflets, which anatomy is complicated both in terms of geometrical shape and internal structure. This causes significant difficulties with finding suitable material for this type of implants. The most frequently used methods of obtaining material for that purpose are based on the processing of biopolymers (e.g. electrospinning) and also on extraction of porcine pericardial tissue. This paper presents a new concept of composite biomaterial based on shape memory alloys (SMA) with biopolymer matrix. The SMA thin fibers imitate collagen fibers in aortic valve leaflets which stabilize the aortic valve motion and reduce stresses. The numerical simulation of blood flow was done to verify assumptions and investigate the extent of deformation of the new composite structure.