RESUMEN
BACKGROUND: Carotid endarterectomy (CEA) is a common, well-developed surgical procedure. Although surgical simulation is gaining in importance for residency training, CEA practice opportunities for surgical residents are limited. OBJECTIVE: To describe a new haptic CEA model. METHODS: Six bovine placentas were used to create the model. Each placenta provided about 6 large arterial and venous bifurcations. In total, 36 large-vessel bifurcations were dissected and prepared for the CEA simulation. Bovine placenta vessels were arranged to simulate the common carotid artery (CCA), internal carotid artery (ICA), and external carotid artery (ECA). The diameters and wall thicknesses were measured and compared with human CCA, ICA, and ECA parameters. RESULTS: All bovine placentas provided vessels suitable for modeling carotid artery bifurcations and CEA training. Mean ± SD diameters of simulated CCAs, ECAs, and ICAs were 11.2 ± 1.8, 4.3 ± 0.5, and 9.8 ± 3.0 mm, respectively, from nondilated veins and 8.7 ± 1.4, 4.4 ± 1.3, and 7.2 ± 1.7 mm, respectively, from nondilated arteries. Mean vessel wall thicknesses were 2.0 ± 0.6 mm for arteries and 1.4 ± 0.5 mm for veins. Placental vessel tissue had dimensions and handling characteristics similar to those of human carotid arteries. The CEA procedure and its subtasks, including vessel-tissue preparation and surgical skills performance, could be reproduced with high fidelity. CONCLUSION: A bovine placenta training model for CEA is inexpensive and readily available and closely resembles human carotid arteries. The model can provide a convenient and valuable simulation and practice addition for vascular surgery training.
Asunto(s)
Arteria Carótida Común/cirugía , Arteria Carótida Externa/cirugía , Arteria Carótida Interna/cirugía , Endarterectomía Carotidea/métodos , Modelos Animales , Placenta/irrigación sanguínea , Animales , Bovinos , Femenino , Humanos , Embarazo , Procedimientos Quirúrgicos Vasculares/métodosRESUMEN
BACKGROUND: Acute spinal cord injury (SCI) is commonly treated by elevating the mean arterial pressure (MAP). Other potential interventions include cerebrospinal fluid drainage (CSFD). OBJECTIVE: To determine the efficacy of aggressive MAP elevation combined with intrathecal pressure (ITP) reduction; our primary objective was to improve spinal cord blood flow (SCBF) after SCI. METHODS: All 15 pigs underwent laminectomy. Study groups included control (n = 3); SCI only (n = 3); SCI combined with MAP elevation (SCI + MAP) (n = 3); SCI combined with CSFD (SCI + CSFD) (n = 3); and SCI combined with both MAP elevation and CSFD (SCI + MAP + CSFD) (n = 3). SCBF was measured with laser Doppler flowmetry. RESULTS: In the SCI group, SCBF decreased by 56% after SCI. MAP elevation after SCI resulted in a 34% decrease in SCBF, whereas CSFD resulted in a 59% decrease in SCBF. The combination of CSFD and MAP elevation resulted in a 24% increase in SCBF. The SCI + MAP group had an average ITP increase of 5.45 mm Hg after MAP elevation 1 hour after SCI and remained at that level throughout the experiment. CONCLUSION: Both MAP elevation alone and CSFD alone led to only short-term improvement of SCBF. The combination of MAP elevation and CSFD significantly and sustainably improved SCBF and spinal cord perfusion pressure. Although laser Doppler flowmetry can provide flow measurements to a tissue depth of only 1.5 mm, these results may represent pattern of blood flow changes in the entire spinal cord after injury.
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Líquido Cefalorraquídeo , Hemodinámica/fisiología , Hipertensión , Traumatismos de la Médula Espinal/líquido cefalorraquídeo , Traumatismos de la Médula Espinal/fisiopatología , Médula Espinal/irrigación sanguínea , Animales , Modelos Animales de Enfermedad , Flujometría por Láser-Doppler , Masculino , Sus scrofa , PorcinosRESUMEN
OBJECTIVE: Current treatments for cerebral aneurysms are far from ideal. Platinum coils are prone to compaction, and currently used liquid embolics are delivered with angiotoxic agents. This work presents initial in vivo studies of a novel liquid-to-solid gelling polymer system (PPODA-QT), focusing on biocompatibility and effective delivery strategies. METHODS: PPODA-QT was used to embolize surgically created lateral wall carotid artery aneurysms in swine using three delivery strategies. Group 1 aneurysms were completely filled with PPODA-QT (n = 5), group 2 aneurysms were subcompletely (80%-90%) filled (n = 3), and group 3 aneurysms underwent three-dimensional coil placement followed by polymer embolization (n = 3). The study was designed such that three animals per treatment group survived to 1 month. RESULTS: The group 1 delivery strategy (100% filling) resulted in survival of 3/5 animals. This strategy led to aneurysm stretching, which resulted model failure in 2/5 animals. Group 2 aneurysms, although initially <100% filled with the polymer, displayed robust neointimal tissue coverage and complete obliteration after 1 month. Group 3 aneurysms showed less prominent neointimal tissue coverage as well as two instances where excess polymer was found in the parent vessel. The PPODA-QT material showed good biocompatibility with vascular tissue in all animals at 1 month. CONCLUSIONS: This small-scale pilot study highlighted first-time in vivo use of PPODA-QT as an embolic agent for aneurysm treatment. Filling aneurysms to 80% to 90% capacity proved to be a safe and effective delivery strategy, and PPODA-QT showed excellent biocompatibility. This study indicates that future investigation of PPODA-QT for aneurysm embolization is warranted, as it may prove to be a viable alternative to current embolic materials.
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Enfermedades de las Arterias Carótidas/terapia , Embolización Terapéutica/métodos , Aneurisma Intracraneal/terapia , Ensayo de Materiales , Polímeros/farmacología , Glicoles de Propileno/farmacología , Animales , Materiales Biocompatibles/química , Materiales Biocompatibles/farmacología , Reactivos de Enlaces Cruzados/farmacología , Modelos Animales de Enfermedad , Sistemas de Liberación de Medicamentos/métodos , Geles , Transición de Fase , Proyectos Piloto , Polímeros/química , Glicoles de Propileno/química , Tasa de Supervivencia , PorcinosRESUMEN
OBJECT: The authors evaluated whether a polyethylene glycol-based hydrogel sealant system improved dural closures with collagen-based duraplasty onlay grafts. METHODS: Dural defects 1.5 cm in diameter were created in 12 canines and repaired with one of two commercially available duraplasty onlay products. In six animals, hydrogel was applied onto the dural onlays, and the other six animals underwent duraplasty only. Before bone flap replacement, watertight closure was assessed. Before the animals were killed, the craniotomy was reopened, adhesions were rated by a neurosurgeon blinded to the treatment groups, and dural integrity was assessed using pressure testing. RESULTS: The animals that received the hydrogel sealant in addition to the duraplasty withstood intraoperative Valsalva maneuvers up to 20 cm H2O without cerebrospinal fluid (CSF) leakage. The duraplasty-only animals leaked CSF at spontaneous pressures (p = 0.0022). Postoperatively, all six duraplasty-only dogs developed CSF subcutaneous accumulations, compared with only one (16.7%) dog who underwent hydrogel application (p = 0.0152). At the time of harvesting (8 weeks after implantation), duraplasty-only dogs had extensive scarring between the bone flap and the dura mater (median adhesion score 4, range 3-4). The animals receiving hydrogel showed minimal scarring (median adhesion score 0.5, range 0-2). In hydrogel-treated dogs, the mean adhesion score was 82.6% lower than the scores in duraplasty-only animals (p = 0.0043). In animals receiving hydrogel, the mean dural leak pressure was 56.8 +/- 2.5 cm H2O compared with 9.8 +/- 3.8 cm H2O in duraplasty-only dogs (p = 0.0392). Application of the hydrogel was not associated with neurotoxicity, delayed healing, degenerative changes, or increased dura-cortex adhesions. CONCLUSIONS: The hydrogel sealant applied to collagen-based dural grafts significantly reduced CSF leakage and functioned as an adhesion barrier. Such technology could be an important tool for cranial surgery.
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Craneotomía , Duramadre/cirugía , Hidrogel de Polietilenoglicol-Dimetacrilato/uso terapéutico , Procedimientos de Cirugía Plástica/métodos , Tensoactivos/uso terapéutico , Animales , Colágeno , Perros , Femenino , Procedimientos de Cirugía Plástica/efectos adversos , Adherencias Tisulares/etiología , Adherencias Tisulares/prevención & control , Trasplante HeterólogoRESUMEN
OBJECTIVE: We sought to expand our assessment of calcium alginate as an embolic agent in an aneurysm model in swine that survived from 30 to 90 days. The objective of this study was to assess the biocompatibility and stability of calcium alginate in aneurysms in vivo. METHODS: Ten models were created from a venous pouch sutured to the carotid artery, simulating flow to a side-wall aneurysm. Eight swine received complete embolizations, and two were less than 50% embolized to be used as controls. Alginate and calcium chloride were injected from concentric-tube microcatheters to form a mass that filled the aneurysm pouch. RESULTS: Angiography and histology verified complete aneurysm occlusion and neck healing up to 90 days in eight swine. Both control animal aneurysms ruptured within 8 days. No animals showed evidence of downstream calcium alginate gel propagation. A minor bioactive response to the alginate gel was noted at 30 days, and fibrous tissue grew over the aneurysm orifice, sealing off the defect. No degenerative or inflammatory response was observed. At 90 days, moderate fibrous tissue surrounded the alginate. Tissue growth across the aneurysm neck remained complete and stable with no signs of neointimal growth into the parent vessel. CONCLUSION: Calcium alginate was an effective endovascular occlusion material that filled the aneurysm and provided an effective template for tissue growth across the aneurysm neck after 30 days and up to 90 days. Complete filling of the aneurysm with calcium alginate ensures stability, biocompatibility, and optimal healing for up to 90 days in swine.
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Alginatos/uso terapéutico , Aneurisma/terapia , Materiales Biocompatibles/uso terapéutico , Arteria Carótida Común , Embolización Terapéutica/métodos , Alginatos/administración & dosificación , Aneurisma/diagnóstico por imagen , Aneurisma/patología , Animales , Oclusión con Balón , Materiales Biocompatibles/administración & dosificación , Modelos Animales de Enfermedad , Ácido Glucurónico/administración & dosificación , Ácido Glucurónico/uso terapéutico , Ácidos Hexurónicos/administración & dosificación , Ácidos Hexurónicos/uso terapéutico , Ensayo de Materiales , Radiografía , PorcinosRESUMEN
OBJECTIVE: We sought to expand our assessment of calcium alginate as an embolic agent in an animal model of a cerebral arteriovenous malformation (AVM). The objective of this study was to assess the long-term biocompatibility and stability of calcium alginate in AVM swine models that survived from 1 to 6 months. METHODS: The swine model included a carotid-jugular anastomosis to redirect flow to the rete mirabile (RM), thereby simulating flow to an AVM. Alginate and the reactive component, calcium chloride, were injected from double-lumen or concentric-tube microcatheters to form an occlusion of the RM feeding vessel and the inferior portion of the RM. RESULTS: Angiography and histology verified complete occlusion of the RM feeding vessel for up to 6 months in eight of nine swine. Blood flow remained open to the superior portion of the RM and the circle of Willis. No evidence of downstream calcium alginate gel was seen in the follow-up angiograms or the histological preparations of the circle of Willis. A minor bioactive response to the alginate gel was noted at 1 month, yet no degenerative or inflammatory response was seen. At 6 months, there was moderate fibrous tissue around the alginate, which further sealed off flow to the embolized areas of the RM. CONCLUSION: Over a period of 6 months, calcium alginate was an effective endovascular occlusion material that blocked blood flow to the inferior portion of the RM. The chronic AVM model verified the long-term stability and biocompatibility of calcium alginate.
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Alginatos , Malformaciones Arteriovenosas/terapia , Embolización Terapéutica/métodos , Animales , Materiales Biocompatibles , Modelos Animales de Enfermedad , Ácido Glucurónico , Ácidos Hexurónicos , PorcinosRESUMEN
OBJECTIVE: Watertight dural repairs are difficult to achieve, and cerebrospinal fluid leakage causes complications and extends hospital stays. Therefore, a novel synthetic hydrogel film was evaluated as an adjunct to dural closure in a canine model. METHODS: The self-polymerizing, absorbable, and biocompatible hydrogel was sprayed onto tissue and formed a flexible, adherent sealant. A 2-cm incision of cranial dura and arachnoid was created in 26 adult dogs and loosely repaired. Hydrogel was applied over the 2-mm dural gap in 13 dogs; 13 control dogs received no hydrogel application. RESULTS: All dogs remained neurologically intact. Valsalva tests conducted at 1, 4, 7, and 56 days were associated with mean leakage pressures (+/- standard error of the mean) of 5 +/- 0, 5 +/- 0, 7 +/- 2, and 13 +/- 8 cm H(2)O in the controls and of 53 +/- 2, 37 +/- 11, 42 +/- 6, and 48 +/- 4 in the treated animals (P = 0.001, 0.053, 0.010, 0.035, respectively, at each time point; one-tailed t test). Histopathological analysis revealed minimal changes. CONCLUSION: The hydrogel-treated animals exhibited normal progression of dural healing, no dural adhesions, and no underlying effects on the brain. Although dural healing progressed normally, the control animals displayed marked peridural adhesions. The results of this in vivo study suggest that hydrogels, such as that used here, may significantly decrease cerebrospinal fluid leakage, thereby increasing the safety and effectiveness of dural closure in patients and facilitating surgical reexploration.
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Duramadre/cirugía , Metilgalactósidos/uso terapéutico , Adhesivos Tisulares/uso terapéutico , Animales , Modelos Animales de Enfermedad , Perros , Duramadre/patología , Masculino , Procedimientos Neuroquirúrgicos/efectos adversos , Efusión Subdural/etiología , Efusión Subdural/patología , Efusión Subdural/prevención & control , Adherencias Tisulares/etiología , Adherencias Tisulares/patología , Adherencias Tisulares/prevención & controlRESUMEN
OBJECTIVE: We sought to assess the stability of calcium alginate as an embolic agent in an animal model of a cerebral arteriovenous malformation (AVM). Swine cerebral AVM models were used to test the injectability, radiographic visualization, mechanical stability, and biocompatibility of calcium alginate as an occlusive agent. METHODS: The swine cerebral AVM model included a carotid-to-jugular anastomosis to increase flow to the rete mirabile (RM), thereby simulating the pressure gradient and shunted blood flow of an AVM. Alginate and the reactive component, calcium chloride, were injected from double-lumen microcatheters to form a complete RM occlusion in the "acute swine" AVM model and a partial occlusion in a "survival swine" model. RESULTS: Angiographic and histological results verified complete occlusion of the left RM in acute animals when alginate was injected in stages. Partial RM occlusion in the survival animals blocked blood flow to the inferior portion of the RM but left flow open to the superior portion of the RM and the circle of Willis. One-week survival results showed that the alginate remained a stable occlusive material. Histological results showed a minor bioactive response and encapsulation of the alginate polymer, thereby increasing the stability and effective occlusion of the embolization material. CONCLUSION: Calcium alginate proved to be an effective endovascular occlusion material that blocked blood flow to the swine RM. The swine AVM models provided assessment of alginate injectability and effective occlusion and provided initial in vivo characteristics of alginate stability and biocompatibility.