[Removal of retrievable inferior vena cava filters 90 days after implantation in an ovine model: is there a time limit for removal?]. / Cuál es el tiempo límite para retirar un filtro de vena cava? Filtros opcionales de vena cava inferior: recuperación 90 días después de su implantación. Modelo ovino.

OBJECTIVE: To study the feasibility and safety of removing retrievable Günther-Tulip vena cava filters (GTFs) 90 days after their implantation in an ovine model. MATERIAL AND METHODS: Thirty GTFs were implanted in 30 ewes and retrieval was attempted at 90 days. Conventional cavography was performed in all cases before and after retrieval in order to evaluate inferior vena cava patency and record dimensions. The presence of complications related to placement and retrieval of the filter from the inferior vena cava was also recorded. The force required to remove the filters was measured using a modified commercial dynamometer adapted to the GTF retrieval set. Histologic study focused on the inferior vena cava wall. RESULTS: Implantation was performed successfully in all cases (100%). One ewe developed a small focus of thrombosis around 1 of the legs of the filter and another presented a small thrombus within the filter. Retrieval of the filter was attempted in all 30 sheep at 90 days and the result was satisfactory in all but 1 case (96.6%). None of the GTFs required a force greater than 12 N to disengage the hooks of the filter from the wall. No complications were detected on venacavography or at autopsy. Variable degrees of fibrosis were observed in the histologic study. CONCLUSIONS: Retrieval of GTFs 90 days after implantation in an ovine model was feasible, safe, and easy, and required little force (median, 4.2 N).

¿Cuál es el tiempo límite para retirar un filtro de vena cava? Filtros opcionales de vena cava inferior: recuperación 90 días después de su implantación. Modelo ovino / Removal of retrievable inferior vena cava filters 90 days after implantation in an ovine model: is there a time limit for removal?

OBJETIVO: Estudiar la posibilidad y la seguridad de recuperarfiltros opcionales de vena cava Günther-Tulip (FGT)a los 90 días de su implantación inicial en un modelo animalovino.MATERIAL Y MÉTODOS: Se implantaron 30 FGT en otrastantas ovejas hembras y se intentó recuperarlos 90 días despuésde su implantación. Se realizó cavografía convencionalen todos los casos antes y después de la recuperación, paraevaluar la permeabilidad de la vena cava. Se obtuvieron medidasde la vena cava y se documentó la presencia de complicacionesrelativas a la implantación y recuperación delfiltro de vena cava inferior (VCI). Se midió la fuerza requeridapara recuperar los filtros de vena cava con un dinamómetrocomercial modificado y adaptado al equipo de recuperaciónde FGT. El estudio histológico se centró en lapared de la VCI.RESULTADOS: La implantación se efectuó con éxito en todoslos casos (100%). Una oveja desarrolló un pequeño focode trombosis en una de las patas del filtro y otra presentó untrombo pequeño en el interior del filtro. Se intentó la recuperacióndel filtro en las 30 ovejas y, excepto en un caso, elresultado fue satisfactorio (96,6%). En la recuperación delos 30 FGT, la fuerza necesaria para desenganchar las patasdel filtro de la VCI fue menor de 12 newtons (N). No se observóninguna complicación en los cavogramas ni en la autopsia.Se observaron diferentes grados de fibrosis en el estudiohistológico.CONCLUSIONES: En un modelo animal ovino, la recuperaciónde FGT a los 90 días de su implantación es posible, seguray fácil, y requiere poca fuerza (mediana: 4,2 N)

OBJECTIVE: To study the feasibility and safety of removingretrievable Günther-Tulip vena cava filters (GTFs) 90 daysafter their implantation in an ovine model.MATERIAL AND METHODS: Thirty GTFs were implanted in30 ewes and retrieval was attempted at 90 days. Conventionalcavography was performed in all cases before and afterretrieval in order to evaluate inferior vena cava patency andrecord dimensions. The presence of complications related toplacement and retrieval of the filter from the inferior vena cavawas also recorded. The force required to remove the filters wasmeasured using a modified commercial dynamometer adaptedto the GTF retrieval set. Histologic study focused on the inferiorvena cava wall.RESULTS: Implantation was performed successfully inall cases (100%). One ewe developed a small focus ofthrombosis around 1 of the legs of the filter and anotherpresented a small thrombus within the filter. Retrieval ofthe filter was attempted in all 30 sheep at 90 days and theresult was satisfactory in all but 1 case (96.6%). None ofthe GTFs required a force greater than 12 N to disengage thehooks of the filter from the wall. No complications weredetected on venacavography or at autopsy. Variable degreesof fibrosis were observed in the histologic study.CONCLUSIONS: Retrieval of GTFs 90 days after implantationin an ovine model was feasible, safe, and easy, and requiredlittle force (median, 4.2 N)

[Research study on renal targeted chemotherapy with magnetic harpoons and intravenous administration of ferro-carbon nanoparticles]. / Estudio experimental sobre quimioterapia focalizada en riñón mediante arpón magnético y administración intravenosa de nanopartículas ferrocarbonosas.

OBJECTIVES: The use of nanoparticules for drug transport is one of the topics with priority interest within the field of biomedical research. Our objective is to show the initial results of an innovative method to focalize drug carrier ferro-carbon nanoparticules to solid organs. We obtained and characterized various types of ferrous magnetic nanoparticules and studied their behaviour in vitro and in vivo in laboratory animals with intrarenal magnetic targets laparoscopically implanted. METHODS: Using a plasma arch we obtained ferro-carbon nanoparticules with the ability to absorb and deliver doxorubicin, showing an excellent behaviour in in vitro rheological studies. Under general anesthesia and control we inserted a gold covered magnetic microharpoon in the left kidney of New Zealand rabbits. At the same time we injected intravenously different doses of various types of nanoparticules. The animals were sacrified ofter pre-established times and pathologic studies of their kidneys, spleens, livers, lungs and bone marrow were carried out. RESULTS: After selection of the most adequafe nanoparticules for our purposes, we ascertained significant differences in the distribution of nanoparticules in postmortem studies, with accumulation in the magnetic target and surrounding renal parenchyma. Nevertheless, the reticuloendothelial system retains a great amount of the injected dose. CONCLUSIONS: Although our magnetic focalization system is effective, nanoparticule temporary protection systems should be tested to allow us avoid the action of the immune system.

Estudio experimental sobre quimioterapia focalizada en riñón mediante arpón magnético y administración intravenosa de nanopartículas ferrocarbonosas / Research study on renal targeted chemotherapy with magnetic harpoons and intravenous administration of ferro-carbon nanoparticles

OBJETIVOS: El empleo de nanopartículas en el transporte de fármacos es actualmente uno de los temas de interés prioritario dentro del campo de la investigación biomédica. Nuestro objetivo es mostrar los resultados iniciales de un método inédito para focalizar en órganos sólidos nanopartículas ferro carbonosas quimioportadoras. Hemos obtenido y caracterizado diversos tipos de nanopartículas ferromagnéticas, y hemos estudiado su comportamiento in vitro e in vivo en animales de experimentación con dianas magnéticas intrarrenales implantadas laparoscópicamente. METODOS: Obtenemos mediante arco de plasma nanopartículas ferro carbonosas capaces de absorber y desorber doxorrubicina y mostrar excelente comportamiento en estudios reológicos in vitro. Bajo anestesia general insertamos mediante control laparoscópico en el riñón izquierdo de conejos de raza neozelandesa un microarpón magnético encapsulado en oro. En el mismo acto inyectamos por vía intravenosa diferentes dosis de distintos tipos de nanopartículas. Los diversos lotes de animales se sacrifican tras diferentes tiempos y se analizan histológicamente ambos riñones, bazo, hígado, pulmones y médula ósea. RESULTADOS: Tras haber seleccionado las nanopartículas más adecuadas para nuestros fines, hemos constatado en los estudios post-mortem diferencias significativas en la distribución de las nanopartículas, con cúmulos de las mismas en la diana magnética y en el parénquima renal circundante. No obstante, el sistema retículoendotelial retiene gran parte de la carga inyectada. CONCLUSIONES: Aunque nuestro sistema de focalización magnética resulta efectivo, deben ensayarse sistemas de blindaje temporal de las nanopartículas que les permita eludir la acción del sistema inmune (AU)

OBJECTIVES: The use of nanoparticules for drug transport is one of the topics with priority interest within the field of biomedical research. Our objective is to show the initial results of an innovative method to focalize drug carrier ferro-carbon nanoparticules to solid organs. We obtained and characterized various types of ferrous magnetic nanoparticules and studied their behaviour in vitro and in vivo in laboratory animals with intrarenal magnetic targets laparoscopically implanted. METHODS: Using a plasma arch we obtained ferro-carbon nanoparticules with the ability to absorb and deliver doxorubicin, showing an excellent behaviour in in vitro rheological studies. Under general anesthesia and control we inserted a gold covered magnetic microharpoon in the left kidney of New Zealand rabbits. At the same time we injected intravenously different doses of various types of nanoparticules. The animals were sacrified ofter pre-established times and pathologic studies of their kidneys, spleens, livers, lungs and bone marrow were carried out. RESULTS: After selection of the most adequafe nanoparticules for our purposes, we ascertained significant differences in the distribution of nanoparticules in postmortem studies, with accumulation in the magnetic target and surrounding renal parenchyma. Nevertheless, the reticuloendothelial system retains a great amount of the injected dose. CONCLUSIONS: Although our magnetic focalization system is effective, nanoparticule temporary protection systems should be tested to allow us avoid the action of the immune system (AU)

Retrievability of uncoated versus paclitaxel-coated Günther-Tulip IVC filters in an animal model.

PURPOSE: To compare in a pilot study, the retrievability and inferior vena cava (IVC) wall reaction elicited by uncoated and paclitaxel-coated Günther-Tulip filters in the animal model. MATERIALS AND METHODS: Three groups with five pigs each underwent infrarenal IVC implantation of Günther-Tulip filters. Paclitaxel-coated filters were used in Groups A and B and uncoated filters were used in Group C. Filters were removed at 14, 19, 22, 26, and 30 days after implantation. A laparotomy was performed to remove filters from animals in group A and filters from animals in groups B and C that could not be retrieved via the right transjugular approach. Filter-induced venous wall changes were evaluated by examination of IVC venography, feasibility of filter removal at different implantation times, and laparotomy and microscopic findings. Feasibility of filter retrieval and venous wall changes were correlated. RESULTS: IVC cavography showed no abnormality. Filters in animals in group B were uneventfully removed by a right jugular approach. Uncoated filter removal was not feasible in three of five animals in group C (19, 22, and 26 days). Microscopically, animals in group A had absent filter-induced IVC wall changes at 14, 19, 22, and 26 days and minimal changes at 30 days post implantation; animals in group B had absent filter-induced IVC wall changes at 14, 19, and 22 days and minimal changes at 26 and 30 days; animals in group C had moderate filter-induced IVC wall changes at 14 days and severe changes at 19, 22, 26, and 30 days. CONCLUSIONS: This pilot study suggests that endothelial reaction to the presence of IVC filters in the porcine model is diminished by addition of paclitaxel coating to these filters. Further studies are necessary to substantiate these results.