Computational fluid dynamics improvements and in vitro tests of a proposed transventricular axial blood pump

Heart failure is a chronic disease that affects thousands of people around the world, being characterized by the inability of one's heart to adequately pump their blood according to their body's needs. Its treatment may be performed through heart transplant. However, ventricular assist devices (VADs) can be used as a way to assist the patient while they wait for a transplant or as destination therapy, with them being responsible for the patients increase in the life expectancy. These devices are pumps that help supply the adequate cardiac output to the body. But the procedures used to implant this kind of device, the size and geometry of the pump are vital for the surgery success and assurance safety patient recuperation. Because of that many important researches center try to find pump geometry that comply these characteristics and comply human blood physiology. Then the reduction in size of these systems, which increases their reliability, biocompatibility and robustness, is essential to the complete implantation of the VADs, which is the main focus of the current state of art.

Safety control architecture for ventricular assist devices

ABSTRACT: In patients with severe heart disease, the implantation of a ventricular assist device (VAD) may be necessary, especially in patients with an indication for heart transplantation. For this, the Institute Dante Pazzanese of Cardiology (IDPC) has developed an implantable centrifugal blood pump that will be able to help a diseased human heart to maintain physiological blood flow and pressure. This device will be used as a totally or partially implantable VAD. Therefore, performance assurance and correct specification of the VAD are important factors in achieving a safe interaction between the device and the patient's behavior or condition. Even with reliable devices, some failures may occur if the pumping control does not keep up with changes in the patient's behavior or condition. If the VAD control system has no fault tolerance and no system dynamic adaptation that occurs according to changes in the patient's cardiovascular system, a number of limitations can be observed in the results and effectiveness of these devices, especially in patients with acute comorbidities. This work proposes the application of a mechatronic approach to this class of devices based on advanced control, instrumentation, and automation techniques to define a method to develop a hierarchical supervisory control system capable of dynamically, automatically, and safely VAD control. For this methodology, concepts based on Bayesian networks (BN) were used to diagnose the patient's cardiovascular system conditions, Petri nets (PN) to generate the VAD control algorithm, and safety instrumented systems to ensure the safety of the VAD system.

Single axis controlled hybrid magnetic bearing for left ventricular assist device: hybrid core and closed magnetic circuit.

In previous studies, we presented main strategies for suspending the rotor of a mixed-flow type (centrifugal and axial) ventricular assist device (VAD), originally presented by the Institute Dante Pazzanese of Cardiology (IDPC), Brazil. Magnetic suspension is achieved by the use of a magnetic bearing architecture in which the active control is executed in only one degree of freedom, in the axial direction of the rotor. Remaining degrees of freedom, excepting the rotation, are restricted only by the attraction force between pairs of permanent magnets. This study is part of a joint project in development by IDPC and Escola Politecnica of São Paulo University, Brazil. This article shows advances in that project, presenting two promising solutions for magnetic bearings. One solution uses hybrid cores as electromagnetic actuators, that is, cores that combine iron and permanent magnets. The other solution uses actuators, also of hybrid type, but with the magnetic circuit closed by an iron core. After preliminary analysis, a pump prototype has been developed for each solution and has been tested. For each prototype, a brushless DC motor has been developed as the rotor driver. Each solution was evaluated by in vitro experiments and guidelines are extracted for future improvements. Tests have shown good results and demonstrated that one solution is not isolated from the other. One complements the other for the development of a single-axis-controlled, hybrid-type magnetic bearing for a mixed-flow type VAD.

Single axis controlled hybrid magnetic bearing for Left ventricular assist device: hybrid core and closed magnetic circuit

In previous studies,we presented main strategies for suspending the rotor of a mixed-flow type (centrifugal and axial) ventricular assist device (VAD), originally presented by the Institute Dante Pazzanese of Cardiology(IDPC), Brazil. Magnetic suspension is achieved by the use of a magnetic bearing architecture in which the activecontrol is executed in only one degree of freedom, in the axial direction of the rotor.Remaining degrees of freedom,excepting the rotation, are restricted only by the attraction force between pairs of permanent magnets. This study is part of a joint project in development by IDPC and Escola Politecnica of São Paulo University, Brazil. This articleshows advances in that project, presenting two promising solutions for magnetic bearings. One solution uses hybrid cores as electromagnetic actuators, that is, cores thatcombine iron and permanent magnets. The other solution uses actuators, also of hybrid type, but with the magneticcircuit closed by an iron core.After preliminary analysis, a pump prototype has been developed for each solution andhas been tested. For each prototype, a brushless DC motor has been developed as the rotor driver. Each solution wasevaluated by in vitro experiments and guidelines are extracted for future improvements.Tests have shown goodresults and demonstrated that one solution is not isolated from the other. One complements the other for the development of a single-axis-controlled, hybrid-type magnetic bearing for a mixed-flow type VAD.