In Silico Hemodynamics and Filtering Evaluation of a Commercial Embolic Protection Device.

During the last years, several kinds of Embolic Protection Devices (EPD) have been developed, with the aim of minimizing complication caused by thrombi generated during Carotid Artery Stenting (CAS). These devices are capable of capturing small particles generated during the intervention, avoiding cerebral stroke and improving the outcomes of the surgery. However, they have associated complications, like the increase on flow resistance associated by their use or the lack of knowledge on their actual filtration efficiency for thrombi of low size. Current work proposes a validated computational methodology in order to predict the hemodynamic features and filtering efficiency of a commercial EPD. It will be observed how Computational Fluid Dynamics predicts pressure drop with fair agreement with the experimental measurements. Finally, this work analyzes the filtration efficiency and the influence of the distribution of injected particles on this parameter. The capabilities of the filter for retaining particles of diameter below the pore size is, additionally, discussed.

Análisis de la repercusión hemodinámica de dispositivos de protección embólica de red en un modelo in vitro / Hemodynamic impact analysis of mesh-type embolic protection devices in an in vitro model

INTRODUCCIÓN: los dispositivos de protección embólica tipo red para procedimientos endovasculares carotídeos (DPEr) son de uso habitual. Su objetivo es disminuir el riesgo de embolia cerebral secundaria a la manipulación y rotura de placa. Sus diferentes características hacen sospechar un distinto comportamiento que puede afectar a su eficacia. OBJETIVO: valorar la repercusión hemodinámica provocada por los DPEr analizando su resistencia al flujo en un modelo hemodinámico in vitro y comparar los resultados entre distintos dispositivos. MATERIALES Y MÉTODOS: se construyó un modelo de flujo pulsátil con suero salino fisiológico (SSF) y se estudiaron 4 DPEr distintos con 5 mediciones por dispositivo para conocer el gradiente de presión en mmHg y resistencia en unidades de resistencia periférica (URP) antes y después de su despliegue. Se utilizó la prueba de los rangos con signo de Wilcoxon para datos pareados y el análisis de dos vías de Friedman de varianza por rangos de muestras. Se consideraron significativos los resultados con una p < 0,05. RESULTADOS: se realizaron 60 mediciones: 10 basales, 10 con catéter portador y 40 con filtro desplegado. El DPEr1 presentó la mayor resistencia (0,88 ± 0,04 URP), significativamente mayor al resto (p = 0,041). El DPEr4 tuvo una resistencia mayor a DPEr2 y DPEr3 (0,70 ± 0,02 frente a 0,57 ± 0,08 y 0,57 ± 0,02 URP, respectivamente), aunque no significativa (p = 0,78). No se observaron diferencias entre los DPEr2 y DPEr3. La forma de cono simétrica se asoció con mayor resistencia (p = 0,002). No se observaron diferencias de los parámetros medidos en función del material de fabricación. CONCLUSIONES: existen diferencias en los DPEr en cuanto a resistencia al flujo que dependen de su diseño y porosidad. Los DPEr con mayor resistencia son el DPEr1 y DPEr4, mientras que el DPEr2 ofrece la menor resistencia al flujo en detrimento de su eficacia

INTRODUCTION: mesh-type embolic protection devices for carotid endovascular procedures (DPEr) are commonly used, their objective is to reduce the risk of cerebral embolism secondary to plaque manipulation and rupture. Their different characteristics make suspect a different behavior that can affect its effectiveness. Objective: to assess the hemodynamic impact caused by DPEr by analyzing their resistance to flow in an in vitro hemodynamic flow model and compare the results between different devices. MATERIALS AND METHODS: an in vitro pulsatile flow model with physiological saline serum (SSF) was constructed. Four different DPEr were studied with 5 measurements per device to know the pressure gradient in mmHg and resistance in peripheral resistance units (URP) before and after its deployment. The Wilcoxon signed ranges test and Friedman’s two-way analysis of variance by sample ranges were used. Significant results were considered with a p < 0.05 RESULTS: 60 measurements were made: 10 baselines, 10 with carrier catheter and 40 with unfolded filter. The DPEr1 presented the highest resistance (0.88 ± 0.04 URP) significantly higher than the rest (p = 0.041). DPEr4 had a greater resistance to DPEr2 and DPEr3 (0.70 ± 0.02 vs. 0.57 ± 0.08 and 0.57 ± 0.02 URP) although not significant (p = 0.70). No differences were observed between DPEr2 and DPEr3. The symmetrical cone shape was associated with greater resistance (p = 0.002). No differences in the measured parameters were observed depending on the manufacturing material. CONCLUSIONS: there are differences in DPEr in terms of resistance to flow that depend on their design and porosity. The DPEr with the highest resistance are the DPEr1 and DPEr4 while the DPEr2 offers the least resistance to flow at the expense of its effectiveness

Evaluación in vitro de los dispositivos de energía para el sellado de colaterales de vena safena en cirugía de revascularización / In vitro model to assess energy devices for the sealing of saphenous vein collaterals in revascularization surgery

INTRODUCCIÓN: Los dispositivos de sellado por energía permiten la hemostasia de los vasos mediante su coagulación y transección de forma secuencial. OBJETIVOS: Comparar la eficacia in vitro de los principales dispositivos utilizados (electrocoagulación bipolar controlada por temperatura [EB] y bisturí armónico BA]) frente a la ligadura convencional en el sellado de colaterales de vena safena (VS) durante su preparación eventual para la cirugía de bypass. MATERIAL Y MÉTODOS: Estudio experimental in vitro de 25 fragmentos de VS extraída de donante cadáver o remanentes de cirugía de revascularización o amputación. En cada fragmento se realizó un sellado mediante ligadura con seda 3/0 (control) y otro con EB (n = 13) o BA (n = 12). Cada fragmento se incorporó a un circuito cerrado con flujo pulsátil y se aumentó progresivamente la presión hasta llegar a 300 mmHg (presión suprafisiológica) y, posteriormente, hasta provocar la rotura. Se registró el diámetro de las colaterales, la presión de estallido, el punto de fuga y el estudio histológico. RESULTADOS: La presión media de estallido fue ligeramente superior para la EB (788,9 ± 455 mmHg) que para el BA (602,5 ± 363,1 mmHg), aunque sin diferencias significativas (p = 0,268). En un solo caso (BA) se produjo el estallido en la zona de sellado a presiones inferiores a 300 mmHg. El punto de fuga para el BA ocurrió en la zona de sellado en todos los casos (12/12), mientras que para la EB se produjo en la zona de sellado en 8 de 13 fragmentos (p = 0,039). El estudio histológico no mostró diferencias entre ambos métodos. CONCLUSIONES: Los dispositivos de hemostasia por energía presentan una eficacia y seguridad no inferior al de la ligadura en el sellado de colaterales de VS. Dadas su rapidez y fácil manejo, pueden ser útiles en la preparación del injerto venoso durante la cirugía de revascularización. Aunque el EB mostró una mayor resistencia a la rotura al producirse el estallido a presiones suprafisiológicas, este hecho podría no tener relevancia clínica

INTRODUCTION: energy sealing devices achieve hemostasis of the blood vessels through sequential coagulation and transection. OBJECTIVES: to compare the efficacy of the main sealing devices used (Electrothermal Bipolar Tissue Sealing System [EB] and Harmonic Scalpel [HS]) versus conventional vessel ligation of saphenous vein (SV) collaterals. MATERIAL AND METHODS: experimental in vitro study of 25 fragments of SV extracted from cadaveric donor, from residual fragments obtained during amputation or lower limb revascularization procedures. Two venous colateral seals were made on each fragment, one by conventional ligation with 3/0 silk (control) and the other one by EB (n = 13) or HS (n = 12). Each venous fragment was then incorporated into a pulsatile flow circuit, and the pressure was progressively increased until 300 mmHg (supraphysiological pressure) was reached, and, later on, until sealing breakage occurred. Collateral vein diameter, burst pressure, and leakage points were recorded. A histological study was also performed for each energy sealing device. RESULTS: the mean burst pressure was slightly higher for EB (788,9 ±455 mmHg) than for HS (602,5 ± 363,1 mmHg), but without significant differences (p = 0,268). Only in one case (HS) the outbreak occurred in the sealing zone at pressures below 300 mmHg. The leakage point for HS was detected in the sealing zone in all cases (12/12). The leakage point for EB occurred in the sealing zone in 8 of 13 fragments (p = 0,039). The histological study showed no differences. CONCLUSIONS: Vessel sealing devices are as effective for the sealing of saphenous vein collaterals as conventional ligation. These devices may be useful due to their fast sealing time and easy handling during surgical venous graft preparation for lower limb revascularization. Although the EB showed greater strength, the outbreak occurred at supraphysiological pressure, so this fact may not have clinical relevance