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.

Impeller geometry definition of the transventricular assist device

ABSTRACT: According to the World Health Organization, cardiovascular disease is the number one cause of death worldwide, except Africa, where Acquired Immune Deficiency Syndrome is the leading cause of death. In this scenario, the ventricular assist device (VAD) remains the unique alternative to extend patient life until heart transplantation. At Dante Pazzanese Institute of Cardiology, the research and development of an axial flow VAD to be fully implantable within the heart was started. This pump, denominated Transventricular Assist Device (TVAD), can be surgically implanted through a small left intercostal incision in a minimally invasive manner. The goal of this work is to analyze the impeller geometries of the TVAD, to avoid high shear stresses in the fluid and aim for the best conditions to support the circulatory system using computational fluid dynamics and in vitro tests. Different rotor geometries were selected according to the literature; based on the results, the best rotor was elected. This rotor contains a pair of spiral blades of constant and relatively high pitch, which pumps liquid at a flow rate of 3 L/min at 73 mm Hg. It is also expected that this rotor presents a moderate hemolysis since the shear rate is acceptable.

Estudio de la maduración de vasos del metaxilema asociada al medio de crecimiento en raíces de soya (glycine max (L) merr) / Study of metaxylem vessels related to the growing medium in soybean (glycine max (L) merr) roots

El cultivo de plantas bajo condiciones hidropónicas controladas es común en investigaciones botánicas. No obstante, la distribución y anatomía de la raíz en estas condiciones debe ser considerada debido a que puede variar en respuesta al medio de crecimiento. En el presente estudio se evaluaron dos genotipos de soya `Dokoy' `Conquista', de uso potencial en agroecosistemas venezolanos. Se determinó el crecimiento del sistema radical, diferencias en los estadios de maduración del metaxilema, y se estimo el flujo axial mediante la ley de Hagen-Poiseuille. Igual cantidad de plántulas de ambos genotipos fueron transplantadas simultáneamente a contenedores con arena y a un sistema hidropónico con solución nutritiva solamente. En plantas de 33 días de edad no se observaron diferencias en peso seco y superficie radical en las dos condiciones. Sin embargo, la longitud de las raíces individuales que integraron un mismo sistema radical fue mayor en solución nutritiva en ambos genotipos. En solución nutritiva la maduración de los vasos en ambos genotipos ocurrió a mayor distancia del ápice que en raíces en arena. La tasa de flujo axial relativo estimado fue mayor en `Conquista' creciendo en arena que en solución nutritiva, probablemente debido a que a 4cm del ápice los vasos del metaxilema tardío presentaron un estadio más avanzado de maduración caracterizado por la desintegración del protoplasto. `Doco' en el mismo tratamiento y a una misma distancia del ápice presentó elementos de vasos menos maduros. La tasa de flujo axial relativo estimada en solución nutritiva fue significativamente menor que en arena en los dos genotipos

Sistema para análise do desempenho de uma bomba axial para assistência circulatória temporária / System for performance analysis of an axial pump for assisted temporary circulatory

As Bombas de fluxo axial com localização intraventricular representam um método promissor para a assistência cardíaca temporária pela eficiência e praticidde. Este trabalho apresenta um sistema para utilização na análise do desempenho durante o desenvolvimento de bombas axiais. No trabalho foram utilizadas técnicas e metodologias da análise dimensional para o estudo do comportamento da bomba em modelo ampliado

Abstract - The Axial Pump for intraventricular location represents a promising

Indices de hemodiálise e visualizaçäo do fluxo na "Spiral Pump" (SP), uma bomba centrífuga de sangue por fuso crônico / Hemodialysis indices and visualization of the flow in \"Spiral Pump\" (SP), a blood centrifugal pump for conic spindle

A "Spiral Pump" (SP) é uma bomba de sangue que utiliza, simultaneamente, os princípios de bombeamento axial e centrífugo, através da rotação de um fuso cônico. As características hidrodinâmicas da SP foram estudadas em diversas condições de bombeamento, utilizando um circuito composto de tubos e reservatório plásticos, com 500 ml de solução água-glicerina (37 por cento). O comportamento do fluxo foi estudado nas áreas mais importantes da bomba utilizando um plano de luz laser estroboscópica. Partículas plásticas, suspensas na solução, foram iluminadas pela luz laser durante o funcionamento da bomba. Vários testes de hemólise foram realizados "In Vitro" utilizando sangue bovino, simulando duas condições de bombeamento: bomba de assistência ventricular esquerda e bomba de circulação e oxigenação extracorpórea

Abstract: The Spiral Pump (SP) is a blood pump that utilizes the two well known centrifugai and axial pumping principies, simultaneously. The hydrodynamic performance of the pump was studied at severa! test conditions, using a closed circuit loop with plastic tubes and reservoir, filled with 500 mi of 37% glycerin-water solution. The results show that the SP has good pumping performance. The flow behavior was studied in the most important areas of the pump using a stroboscopic planar helium-neon laser light. Amberlite plastic particles (80 mesh) were used in suspension in the solution and were illuminated by the laser light during the pumping process. Severa! in vitro hemolysis tests were performed using bovine blood, simulating two pump conditions: as left ventricular assist device and as cardiopulmonary bypass